CN102302945A

CN102302945A - Method for preparing propene by catalytic cracking

Info

Publication number: CN102302945A
Application number: CN201110294298A
Authority: CN
Inventors: 郭洪臣; 张小乐; 刘春燕; 常旭生; 刘家旭; 梁翠翠
Original assignee: Dalian University of Technology
Current assignee: Dalian University of Technology
Priority date: 2011-10-04
Filing date: 2011-10-04
Publication date: 2012-01-04
Anticipated expiration: 2031-10-04
Also published as: CN102302945B

Abstract

The invention belongs to the field of petrochemical industry and relates to a method for preparing propylene by catalytic cracking. It is characterized in that the ZSM-5 molecular sieve crystal nucleus is first synthesized, and the silicon source, the template agent, and deionized water are made into a gel solution; the aluminum source is made into a solution with inorganic acid or alkali, and deionized water; the solution is mixed under stirring. Add it into the glue to form a uniform gel; hydrothermally crystallize the gel, and stop the crystallization before the end of the crystallization induction period; then prepare the ZSM-5 crystal nucleus as a catalytic cracking catalyst, and the obtained catalyst is used for olefin cracking to produce Take propylene and isobutylene. The beneficial effect of the present invention is that the ZSM-5 crystal nucleus catalyst itself only has a weak acid center, and the crystal grains are extremely small, without any modification treatment, and without any negative pressure or diluent gas conditions, it can significantly inhibit hydrogen transfer aromatization, etc. Side reactions, thereby improving the selectivity of the target product, making the catalytic cracking process simpler and reducing the cost of the catalyst.

Description

A kind of method of preparing propylene by catalytic cracking

Technical field

The invention belongs to petrochemical industry, relate to a kind of method of preparing propylene by catalytic cracking, the catalyst applications that is specifically related to a kind of new Preparation of catalysts and gained is in the method for producing propylene and isobutene.

Background technology

Liquefied petroleum gas (LPG) is the general name of C3, C4 hydrocarbon, is mainly derived from the manufacture gas of crude oil processing, associated gas, gas field associated gas.The LPG that China produces comes catalytic cracking to produce the gasoline device more than 95%, steam cracking is produced oil refining processing unit (plant)s such as ethylene unit, platforming production aromatic device and hydrocracking, coking.In recent years, along with the continuous enlarging of domestic refinery and newly-built, liquefied gas output constantly increases.

Having Chinese every year the LPG more than 70% to be used as domestic fuel approximately burns.Therefore, the chemical utilization rate of LPG is low.On the other hand, along with the fast development of natural gas in domestic fuel market, civil LPG will reduce gradually.Therefore, the C4 liquefied gas is converted into chemical products with high added-value, has important economic implications.

Propylene is one of important petrochemical industry basic material.In recent years, along with increasing rapidly of demands such as its downstream derivative polypropylene, acrylonitrile, expoxy propane, especially under the powerful pulling of polypropylene demand, propylene demand worldwide is more and more vigorous.Therefore, the correlation technique of exploitation propylene enhancing is significant.

At present, the source of propylene mainly contains: the accessory substance of ethylene plant's steam cracking, catalytic cracking accessory substance, technologies such as low-carbon alkene disproportionation, dehydrogenating propane and methanol conversion MTP.The steam cracking process exists feed naphtha restriction and high energy consumption problem; Catalytic cracking by-product propylene is an important channel, is contradiction but produce propylene with producing gasoline, and often causes diesel quality to worsen; The low-carbon alkene dismutation is wanted the ethene resource of consume valuable, and the energy consumption of dehydrogenating propane technology is very high, and the economy of the two is but not good; Methanol conversion technology (MTP) is also in experimental stage, and its investment is big, and the influence of environment is still waiting examination.But, carbon four and above olefins by catalytic cracking propylene enhancing method thereof, advantage such as it is extensive to have raw material sources, and reaction condition is gentle, and technology is simple, and is easy to operate.

Isobutene also is one of very important petrochemical industry basic material.Isobutene is mainly used in chemical products such as producing methyl tertiary butyl ether(MTBE), the tert-butyl alcohol, polyisobutene.In recent years, along with the raising of environmental requirement, harsh more to the requirement of decreasing by gasoline olefin technology.This makes the demand rapid growth of methyl tertiary butyl ether(MTBE), and then causes the demand of isobutene to increase severely.

Therefore, if can use cheap C4 liquefied gas to produce propylene and isobutene simultaneously, will have very outstanding meaning.

Following discloses patent and document have been introduced the technology of carbon four and above olefin catalytic cracking to produce propylene thereof:

Patent CN1506343A (2004) has disclosed a kind of method with carbon four and above olefin catalytic cracking to produce propylene thereof.Its technical characterictic is: adopting silica alumina ratio is that 50～1000 ZSM-48 type molecular sieve is the catalyst activity main body, is 400～600 ℃ in reaction temperature, and reaction pressure is 0～0.15MPa, and the liquid phase volume air speed is 10～50h ^-1Under the condition, the propylene selectivity reaches 53.4%, and propene yield reaches 39.6%.

Patent CN1651364A (2005) has disclosed and has a kind ofly produced the particularly method of propylene of light olefin by the hydrocarbon feed that contains C4～C6 alkene.Its technical characterictic is: olefin feedstock contacts with the MCM-22 molecular sieve catalyst, is that 450～650 ℃, reaction pressure are that 0.1～10atm, weight space velocity are 1～50h in reaction temperature ^-1Under the condition, reacted 1 hour, butene conversion is 76.80%, and propene yield is 34.0%; Reacted 10 hours, butene conversion is 66.09%, and propene yield is 29.9%; In ten hours, butene conversion has reduced by 10 percentage points.It is thus clear that the MCM-22 molecular sieve is better to the initial activity of olefin cracking, but its poor stability.

Patent US6049017 (2000), CN1915936A (2005), CN1762931A (2006) have disclosed respectively and used the aperture is the method for the aperture silicoaluminophosphamolecular molecular sieves of 0.3～0.56nm as catalyst propylene enhancing, ethene.Its technical characterictic is: in fluidized-bed reactor, be 400～650 ℃ in reaction temperature, reaction pressure is 0～0.5MPa, and weight space velocity is 0.1～50h ^-1, water vapour/raw material weight ratio is under 0～5 condition, carbon four and above alkene thereof catalytic cracking for producing propylene using and ethene on SAPO-34, and butene conversion is 75.3%, the total recovery of its propylene and ethylene can reach 40%.But these data are that it obtains in the pulse microreactor, have only the reaction result of 0.5～10min.

It is that the mesopore silicoaluminophosphamolecular molecular sieves of 0.6～0.65nm is catalyst, the method for catalytic cracking for producing propylene using that patent CN1927783A (2005) has disclosed a kind of aperture of using.Its technical characterictic is: in fluidized-bed reactor, rich olefins raw material and steam concurrent conditions through the SAPO-11 catalyst, are 400～650 ℃ in reaction temperature down, and reaction pressure is 0～0.5MPa, and weight space velocity is 0.1～50h ^-1, water vapour/raw material weight ratio is under 0～5 condition, productivity of propylene is 35%.

Patent CN101448769A (2009) has disclosed and has a kind ofly prepared the method for propylene by hydrocarbon feed, and wherein said hydrocarbon feed is the hydrocarbon feed that comprises C6 alkene.Its technical characterictic is: make raw material and have 10 yuan of ring passages, silica alumina ratio is 10～200 one-dimensional channels zeolite contact, and said zeolite is selected from TON type, MTT type and EU-2/ZSM-48 zeolite.

Open source literature catalysis journal 2003,24 (2): 119～122 has been introduced the cracking reaction performance of C 4 olefin on the AlSi-ZSM-48 zeolite molecular sieve after the etherificate.The result shows: the total recovery of propylene and two kinds of alkene of ethene can reach more than 40% on the ZSM-48 molecular sieve.But the synthesis condition of AlSi-ZSM-48 is harsh, is prone to association ZSM-5 and other stray crystal.

Open source literature petrochemical industry 2004,33 (Z1): 336～338 have introduced the response characteristic of butylene at SAPO-34 molecular sieve catalytic cracking system propylene/ethylene.The result shows: propylene and ethene have higher selectivity on the SAPO-34 molecular sieve, are 620 ℃ in reaction temperature, and reaction pressure is 0.1MPa, WHSV=3.5h ^-1Under the condition, butene conversion is 80%, and the propylene selectivity reaches 45.6%.But catalyst is prone to the carbon distribution inactivation, and reaction stability is relatively poor.

Open source literature Applied Catalysis A:General 288 (2005) 134-142 have introduced the Y of Different Pore Structures, Beta, MCM-22, ZSM-22, ZSM-23, ZSM-35, ZSM-5, the catalytic pyrolysis performance of C4 alkene on the SAPO-34 equimolecular sieve catalyst.The result shows: middle pore zeolite can suppress hydrogen migration, obtains higher propylene and ethylene selectivity.But catalytic stability is poor, has only the ZSM-5 catalyst to show combined reaction performance preferably.

Open source literature Applied Catalysis A:General 290 (2005) 191-199, Catalysis Communications2005; 6 (11): 742～746, SCI 2005,26 (6): 1140～1142,2007 the 15th volumes of Industrial Catalysis supplementary issue, Catalysis Letters (2009) 130:204～210, Microporous and Mesoporous Materials (2009) 118:44-51 have introduced butylene cracking reaction performance on MCM-22.The MCM-22 molecular sieve obtains higher ethene, propylene selectivity because of having the ten-ring structure similar with ZSM-5, but the supercage structure of its twelve-ring makes the catalyst carbon deposition inactivation fast, and stability is bad.

Open source literature Applied Catalysis A:General 299 (2006) 167～174 has introduced the synthetic ZSM-48 of a kind of hydro-thermal and has used it for the method for butylene cracking system propylene.The author has synthesized the ZSM-48 of a series of Different Silicon aluminum ratios, and has investigated butylene is produced propylene in the ZSM-48 cracking performance.The result shows: compare with HZSM-5, HZSM-48 shows the selectivity of better propylene and ethylene, especially low silica-alumina ratio; But HZSM-48 more is prone to the carbon distribution inactivation by contrast.

The open source literature gas chemical industry 2007,32 (3): 5～10 have introduced ZSM-5 on the continuous fixed bed reactors of normal pressure, the 1-butylene catalytic pyrolysis performance of SAPO-11 and MCM-22 molecular sieve.The result shows: though the duct of 3 kinds of catalyst and acidity there are differences, all can reach thermodynamical equilibrium between the butylene isomer in the pyrolysis product, in butene conversion 50%～70% scope, can obtain preferable propylene selectivity; ZSM-5 shows preferable reactivity and stability in three kinds of catalyst.

Open source literature Journal of Molecular Catalysis 2007; 21 (3): 193～199, Catalysis Communications 2005; 6 (4), 297～300, Applied Catalysis A:General 274 (2004): 167～172 has introduced the reactivity worth of butane producing ethene, propylene through catalytic cracking on the ZSM-23 molecular sieve.The result shows: on the ZSM-23 zeolite molecular sieve, butanes conversion can reach 88%, and propene yield can reach 56%.But this catalyst reaction stability is bad, and the molecular sieve production cost is higher.

Open source literature Chemical Engineer 2007; 137 (2) 14～16, Chemical Engineer 2007; 145 (10) 11～13, Harbin Teachers' Univ.'s natural science journal 2010,26 (2): 57～60, the 1-butylene has been introduced in MCM-49 molecular sieve catalytic cracking producing propylene ethane reactivity worth in Reac Kinet Mech Cat (2010) 100:399～405.The result shows: in reaction temperature is 580 ℃, and 1-butylene dividing potential drop is 0.04MPa, WHSV=9.4h ^-1Under the condition, the overall selectivity of ethene and propylene can reach 72.9%, and ethene and propylene gross production rate can reach 57.3%.But having adopted pure 1-butylene is raw material, has increased the commercial production cost.

The open source literature Chemical Engineer 2007,140 (5): 07～09 has introduced the reactivity worth of 1-butylene preparing propylene by catalytic cracking and ethene on the Ba-MCM-49 molecular sieve catalyst.The result shows: an amount of barium is modified can suppress hydrogen migration and aromatisation side reaction to a certain extent, thereby has improved purpose product propylene and selectivity of ethylene.In reaction temperature is 580 ℃, and 1-butylene dividing potential drop is 0.04MPa, WHSV=9.4h ^-1, react under 1 hour condition, when Ba content is 0.5%,, butene conversion reaches 75..39%, and ethene and productivity of propylene can reach 57.13%; Ba content is 2% o'clock, and butene conversion reaches 68.19%, and ethene and productivity of propylene can reach 55.26%.But the increase of load capacity can make the duct of catalyst stop up, and stability is bad.

Open source literature petroleum journal 2009, supplementary issue (25): 28～31 have introduced the performance of butylene preparing propylene by catalytic cracking on the ITQ-13 molecular sieve.The result shows: in the butylene catalytic cracking reaction, can effectively suppress side reactions such as hydrogen migration and aromatisation through the ITQ-13 molecular sieve of appropriate Si alkanisation modification, the propylene selectivity increases.

Open source literature petrochemical industry 2009,38 (11): 1174～1179 have introduced the reaction rule of butylene catalytic pyrolysis preparing ethylene and propylene on SAPO-34.The result shows: compare with ZSM-5, SAPO-34 molecular sieve diene selective is higher, but less stable.In reaction temperature is 600 ℃, WHSV=2.53h ^-1, water hydrocarbon specific mass is than 0.75 o'clock, and butene conversion is more than 70%, propene yield about 30%.

In sum, ZSM-5 shows higher activity, stability and anti-carbon deactivation than other molecular sieve in the butylene catalytic cracking reaction.Therefore, mainly concentrate on the research of ZSM-5 molecular sieve catalyst in the research aspect the technological development of olefins by catalytic cracking producing light olefins.

Following discloses patent and bibliographical information the method that carbon four and above olefins by catalytic cracking thereof are produced low-carbon alkene on the ZSM-5 molecular sieve catalyst.

Disclosed among the patent EP0109059A1 (1984) and a kind ofly be converted into the method for propylene to C4～C12 alkene.Its technical characterictic is: adopt silica alumina ratio to be not more than 300 ZSM-5 molecular sieve, be reflected at temperature and be 400～600 ℃ with the alkene air speed greater than 50h ^-1Carry out under the condition, but the selectivity of propylene has only 37.98%.

Patent WO9929805A1 (1999) has disclosed a kind of method of producing propylene with C4 and the above olefin feedstock of C4.Its technical characterictic is: the employing silica alumina ratio is 600～2000 high silica alumina ratio ZSM-5 molecular sieve, and being reflected at temperature is 540～580 ℃, and the weight space velocity of raw material is 8.5～25h ^-1Carry out under the condition, propylene initial stage yield is 29.2%, reacts after 500 hours, and propene yield is 23.1%.

Patent CN1284109A (2001) has disclosed a kind of method of using carbon four or carbon four above alkene as the raw material production propylene.Its technical characterictic is: employing sial atomic ratio is a catalyst greater than 180 hydrothermal modification ZSM-5 molecular sieve, and carbon four cracking conversion ratios have only 54%, and propene yield is merely 29%.In addition, catalyst will pass through the preliminary treatment of steam processing/dealuminzation, and production cost is higher.

Patent CN1490288A (2004) has disclosed a kind of method with carbon four and above olefin catalytic cracking to produce propylene thereof.Its technical characterictic is, in the building-up process of type ZSM 5 molecular sieve, added the halogen sodium salt in crystallization process, and the halogen sodium salt is selected from least a among NaF, NaCl or the NaBr.This catalyst is used for carbon four with its above olefin catalytic cracking to produce propylene process, and propene yield reaches 38.2%.

Patent CN1611472A (2005) has disclosed a kind of method that adopts the ZSM-5 molecular sieve of little crystal grain, high silica alumina ratio as the Catalyst Production propylene.Its technical characterictic is: with carbon four and above olefin feedstock thereof, be 100～1000 at silica alumina ratio, particle diameter is not more than on 1 micron the type ZSM 5 molecular sieve catalyst and reacts, and reaction temperature is 500 ℃, and weight (hourly) space velocity (WHSV) is 10h ^-1, the initial yield of propylene reaches 37.9%.

Patent CN1751008A (2006) has disclosed a kind of method of producing ethene and propylene.Its technical characterictic is: the alkene that contains at least a carbon number 4～12 in the raw material; And the saturated hydrocarbons that contains at least a carbon number 1～12 of 10～70wt.%; With the ZSM-5 molecular sieve is catalyst, and in the reaction pressure of 0.05～2MPa, mass space velocity is 32～256hr ^-1, 400～580 ℃ of reaction temperatures condition under carry out the hydrocarbon catalytic cracking reaction, butene conversion is 65～80%, productivity of propylene is about 30%.

It is the method that propylene is produced in the catalytic material cracking with carbon four～carbon eight alkene that patent CN1927780A (2007) has disclosed a kind of.Its technical characterictic is: with silica alumina ratio is that 10～180 ZSM-5 molecular sieve is the catalyst activity main body, is 500 ℃ in reaction temperature, and pressure 0.01～0.2MPa, weight space velocity are 10h ^-1React under the condition, the initial stage yield of purpose product propylene reaches 41%, and selectivity surpasses 55%.’

It is the method that propylene is produced in the catalyst cracking with high-crystallinity ZSM-5 molecular sieve that patent CN1915924A (2007) has disclosed a kind of, and its technical characterictic is: the degree of crystallinity of ZSM-5 molecular sieve is greater than 90%, and silica alumina ratio is 200～600, binder free.580 ℃ of reaction temperatures, mixed c 4 weight space velocity 30h ^-1Condition under react, olefin conversion reaches 81.2%, the propylene selectivity can reach 42.1%.

It is the method for Catalyst Production propylene with the ZSM-5 molecular sieve that patent CN101092326 (2007) has disclosed a kind of.Its technical characterictic is: raw material is C4 or the above alkene of C4, is 400～600 ℃ in reaction temperature, is 0.01～0.3MPa with the absolute manometer reaction pressure, and weight space velocity is 2～50h ^-1Under the condition, reaction is that 20～350 ZSM-5 zeolite is a catalyst with silica alumina ratio, and olefin conversion can reach 80%, and productivity of propylene is 30～50%.

Patent CN101279882A (2008) has disclosed the method for a kind of ZSM-5 of use molecular sieve as the Catalyst Production propylene.Its technical characterictic is: with C4 or its above alkene is raw material, contacts with the ZSM-5 molecular sieve catalyst to produce propylene, ethene.After product separated, C1 and C2 component looped back reactor, and the ratio of C1 and the circulation of C2 component can change between 5～99%.

Open source literature petroleum journal (petrochemical industry) 1994,10 (3): 97～101, the catalysis journal 2004,25 (7): 571～576 have introduced the influence of steam treatment temperature and time to ZSM-5 acidic zeolite and catalyzing butene cracking performance thereof.The result shows: steam treatment can reduce the acid amount and the acid strength of ZSM-5 molecular sieve, obviously improves propylene and selectivity of ethylene and yield in the product, suppresses the production of accessory substance aromatic hydrocarbons and low-carbon alkanes.Remove the non-framework aluminum that produces in the steam treatment process with citric acid, can improve the appearance carbon ability in the duct of ZSM-5 molecular sieve, thereby improve the stability of catalyst.

Open source literature petrochemical industry 2005,34 (Z1): 100～101 have introduced the influence of the ZSM-5 molecular sieve of Different Silicon aluminum ratio to C4 hydrocarbon preparing propylene by catalytic cracking.The result shows: with the increase of silica alumina ratio, catalyst activity is downward trend, and propene yield presents the downward trend again that rises earlier, and propylene selectivity and yield reach 45% and 39% respectively when silica alumina ratio is 300 left and right sides.

Open source literature catalysis journal 2004,25 (8): 602～606 has been introduced the crystallite dimension size C4 olefin cracking has been produced catalyst activity and stable influence in the propylene process.The result shows: it is short that the ZSM-5 molecular sieve of little crystal grain (0.2～0.3 micron of particle diameter) has micropore, external surface area big with characteristics such as the aperture is many, thereby show stronger appearance carbon ability and stability preferably.In reaction temperature is 550 ℃, normal pressure, mass space velocity=10h ^-1Under the condition, the once through yield of initial reaction stage propylene can reach 38%.

In sum, the zeolite crystal of other element of adding and synthesizing high-silicon aluminum ratio, little crystallite dimension can obtain reaction effect preferably in synthetic.But olefin conversion mostly between 60～80%, the overall selectivity 50～70% of propylene and ethene.

Discover, in the reaction of producing propylene with C _ 4 alkene catalytic pyrolysis, the polymerization of butylene--be cracked into the main reaction process, side reaction processes such as simultaneous isomerization, hydrogen migration, cyclisation, dehydrogenation, aromatisation and coking.And above-mentioned side reaction is the main cause that influences the purpose selectivity of product.Main reaction needs more weak acid centre, and strong acid center then is the activated centre of hydrogen migration and aromatisation side reaction.In order to suppress hydrogen migration and aromatisation side reaction, scholars are through carrying out the strong acid center that catalyst surface is removed in various modifications to the ZSM-5 molecular sieve catalyst.

Following patent and document have been introduced the method for coming increased low carbon olefine output through the acidity of the element modified modulation ZSM-5 of coming zeolite molecular sieve catalyst.

Patent CN1274342A (2000) has disclosed a kind of method of producing ethene and propylene through catalyzed conversion from the hydrocarbon feed that contains C4～C12 alkene.Its technical characterictic is: adopt Alkali-Metal Na, K and the metal Cu of IB family, Ag modify catalyst through ion-exchange, impregnating means, prepare the ZSM-5 molecular sieve catalyst that does not contain proton basically.It is raw material that surplus mixed c 4 is taken out in employing, is 600 ℃ in reaction temperature, and weight space velocity is 16.3h ^-1Condition under, the propylene selectivity is 47.5%, propene yield is 34.0%.

Patent CN1490287A (2004) has disclosed a kind of method of producing propylene.Its technical characterictic is: catalyst is selected from the silica-rich zeolite of ZRP series or ZSM-5 class, and silica alumina ratio is 50～300, and modified component is selected from least a in oxide, alkaline earth oxide and the rare-earth oxide of molybdenum oxide, tungsten oxide, phosphorus; Preferred rare earth metal is a lanthanum, and alkaline-earth metal is a calcium.Hydrocarbon mixture with carbon containing four or C 5 monoolefin is a raw material, at low temperature, does not add under the condition of diluent gas, and butene conversion is 78.3%, and propene yield is 27.46%, and yield of ethene is 7.94%.

Patent CN1506342A (2004) has disclosed that a kind of to adopt the ZSM type molecular sieve of load alkaline-earth metal be catalyst, the method for catalytic pyrolysis carbon four and above olefin production propylene thereof.Its technical characterictic is: catalyst is that silica alumina ratio is 38～1000 ZSM-5 or ZSM-11 type molecular sieve, the alkaline-earth metal of load 0.1～10wt.%; The preferred bases earth metal is a kind of among Mg, Ca or the Ba.In reaction temperature is 550 ℃, liquid air speed 15h ^-1Condition under, the selectivity of purpose product propylene reaches 52.7%, propene yield is higher to reach 34.0%.

It is the method for Catalyst Production propylene with the modified ZSM-5 that patent CN1611471A (2005) has disclosed a kind of.Its technical characterictic is: adopting the molecular sieve of the ZSM-5 type of phosphorus modification, low silica-alumina ratio is catalyst, and phosphorus content is 0.1～5% by weight percentage.In reaction temperature is 530 ℃, weight space velocity 10h ^-1Under the condition, the selectivity of purpose product propylene reaches 54.7%, and propene yield reaches 35.6%.

Patent CN1600757A (2005) has disclosed a kind of method of being produced propylene by the hydrocarbon feed that contains C4～C6 alkene.Its technical characterictic is: adopt the zeolite catalyst of alkali metal, alkaline-earth metal or rare earth metal dipping modified ZSM-5/ZSM-11, silica alumina ratio is greater than 30.Olefin feedstock is contacted with the catalyst of modification, is 500～650 ℃, reaction pressure 0.1～8atm, weight space velocity 1～50h in reaction temperature ^-1Under the condition, the propylene selectivity is more than 60%, propene yield about 40%.

Patent CN1676213 (2005) disclosed a kind of on modification high silica ZSM-5 molecular sieve the method for catalytic pyrolysis C4～C7 olefin production propylene.Its technical characterictic is: the zirconium dioxide with little crystal grain is a carrier, is that active component is processed catalyst with the group vib metal oxide that comprises 1～20%wt.%, wherein also contains alkaline earth oxide or rare-earth oxide auxiliary agent.Said zirconic average grain diameter is 10～100nm.In reaction temperature is that 440～470 ℃, 0.3MPa, raw material volume space velocity are 3.0h ^-1Condition under, the C4 olefin conversion is 79～91wt%, the propylene once through yield is about 45%.

It is the method for raw material production propylene with the carbon four and the carbon four above alkene that do not contain diolefin that patent CN101033166A (2007) discloses a kind of.Its technical characterictic is: adopting the type ZSM 5 molecular sieve of heteropoly acid modification is catalyst, and wherein the consumption of heteropoly acid is 5～20%, 500 ℃ of reaction temperatures, and pressure 0.1～0.5MPa, the water oil quality is than 0.5～10, and weight space velocity is 3h ^-1Condition under, the selectivity of purpose product propylene reaches 46%, productivity of propylene is 37%.

Patent CN101172247A (2008) has disclosed a kind of method of producing propylene and ethene.Its technical characterictic is: select for use comprise silica (45～65wt.%) and modified component (10～15wt.%), at least two kinds the ZSM-5 type silica-rich zeolite that modified component is selected from zirconia, magnesia, tungsten oxide and the boron oxide is a catalyst.In reaction temperature is 450 ℃, and reaction pressure is 0.2MPa, and water hydrocarbon ratio is 0.6, and weight space velocity is 3h ^-1Under the condition, the conversion ratio of reactant is 86%, and propene yield is 35%, and yield of ethene is 8%.

It is the method for raw material catalytic cracking for producing propylene using on modified ZSM-5 type molecular sieve with the butylene that patent CN101239879A (2008) has disclosed a kind of.Its technical characterictic is: butene feedstock at first with comprise following component: SiO ₂Carrier and the tungsten oxide reaction of carrying 0.1～20%wt.% on it; Reaction effluent and silica alumina ratio are at least 10 crystal aluminosilicate and contact, and produce propylene.

Patent CN101263095A (2008), CN101263096A (2008) have disclosed hydrocarbon feed respectively and have transformed the method for producing ethene and propylene through the modified ZSM-5 zeolite molecular sieve.Its technical characterictic is: adopt the metal pair zeolite molecular sieve zsm-5 of at least a IB family to carry out modification, make zeolite not contain proton basically.The silica alumina ratio of said zeolite molecular sieve is 800～2000, and raw material C4～C12 alkene is 400～600 ℃ in reaction temperature, and reaction pressure is 0.01～1MPa, and weight space velocity is 1～100h ^-1React under the condition, feed stock conversion is 67～68%, propene yield 20～21%.

It is that raw material carries out the method that catalytic pyrolysis generates propylene and ethene on the modified ZSM-5 zeolite molecular sieve with carbon four～carbon 12 rare hydrocarbon that patent CN101684059A (2010) has disclosed a kind of.Its technical characterictic is: the ZSM-5 molecular sieve so that the silica alumina ratio of phosphorus modification is 10～300, size of microcrystal is 10～800nm is a catalyst, is 450～650 ℃ in reaction temperature, and reaction pressure 0～0.3MPa, weight space velocity are 1～14h ^-1, reacting under water hydrocarbon mass ratio 0.1～10 condition, propene yield reaches about 30%.

Following patent and document also relate to the pentasil zeolites (preferred ZSM series) of at least a modification in P elements or its oxide, alkali metal, alkaline-earth metal, transition metal and the rare earth metal, are used for the reaction of olefins by catalytic cracking producing light olefins.

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Open source literature Catalysis Letters 2005,103 (3/4): 201～210 has introduced the performance of butylene at K/ZSM-5 preparing propylene by catalytic cracking and ethene.Study the different K load capacity and in charging, added N ₂, steam is as the reaction effect of diluent, the result shows: steam is diluent preferably, but under water vapor condition the poor stability of catalyst.

Open source literature petrochemical industry 2006,35 (8): 735～739 have introduced SiO ₂Deposition and reaction condition are produced the propylene Effect on Performance to catalyst C4 olefin cracking.Its technical characterictic is: on the HZSM-5 molecular sieve, deposit SiO ₂Modulation the pore structure and the acidity of catalyst, but SiO ₂Deposition influence the performance of catalyst, the serious blocking catalyst of deposition conference duct.In reaction temperature is that 530 ℃, reaction pressure are that 0.1MPa, raw material weight (hourly) space velocity (WHSV) are 2.0h ^-1, SiO in the catalyst ₂Deposition is under the condition of 7.0wt.%, and the C4 olefin conversion is for having only 42.9%, and propene yield is 28.3%.

Open source literature catalysis journal 2007,28 (6): 567～571 has been introduced the nano-ZSM-5 catalyst to butylene catalytic pyrolysis Effect on Performance, and compares with two kinds of micron H-ZSM-5 catalyst samples (grain size is respectively 1～2 and 1～6 micron).The result shows: the anti-carbon deactivation of nanometer HZSM-5 catalyst is superior to a micron HZSM-5 catalyst, and at normal pressure, reaction temperature is 560 ℃, mass space velocity 7h ^-1React under the condition, when butene conversion and propene yield descend 50% the time, the reaction time on two kinds of micron catalyst is merely 28h, and the reaction time on the nanocatalyst is about 120h.Nano-ZSM-5 molecular sieve acidity is stronger, and side reaction has limited the purpose product selectivity.

Open source literature Chemical Reaction Engineering and technology 2007,23 (3): 193～199 have been introduced the NaOH modified zsm-5 zeolite to the C _ 4 alkene catalytic pyrolysis Effect on Performance.Its technical characterictic is: use the ZSM-5 zeolite molecular sieve of concentration of sodium hydroxide solution as the 0.4mol/L modification, under reaction temperature was 550 ℃, condition of normal pressure, butene conversion can reach more than 78%, and propene yield is greater than 38%.But NaOH modification meeting is broken can pore canal structure of catalyst.

Open source literature Journal of Molecular Catalysis 2008,22 (3): 236～241 have introduced C4 olefin cracking system propylene catalytic performance on the W-ZSM-5 catalyst.When W content was 3.2%, the propylene selectivity and the yield of catalyst were respectively 47.4% and 41.3%.

Open source literature Journal of Molecular Catalysis 2009,23 (1): 11～16 have introduced the adjusting of nanometer HZSM-5 zeolite acidity and to the influence of liquefied gas cracking reaction.Its technical characterictic is: adopt the sodium ion modification can optionally remove the strong acid center of nanometer HZSM-5 zeolite surface, the weak acid center is not then had influence basically.The selectivity of propylene can reach 60%, and propene yield is about 30%.

Open source literature Solid State Sciences 12 (2010): 1278～1282 has introduced butylene and has contained catalytic cracking for producing propylene using and ethylene reaction performance on the mesoporous ZSM-5 after the alkali treatment.Its technical characterictic is: with NaOH solution-treated ZSM-5, stay the room after the catalyst desiliconization, form mesoporous.Introduce mesoporously in the ZSM-5 molecular sieve after the alkali treatment, can improve the performance of butylene catalytic cracking for producing propylene using and ethene, but the reaction stability reduction.

Open source literature petrochemical industry 2010,39 (5): 482～486 have introduced C 4 olefin at CaO-B ₂O ₃/ ZSM-5/SiO ₂Cracking generates the performance of propylene on the catalyst.Its technical characterictic is: in reaction temperature is that to be 0.1MPa, water be 0.2 with carbon four raw materials quality ratio, weight (hourly) space velocity (WHSV) 3h for 520 ℃, reaction pressure ^-1Condition under, the C 4 olefin conversion ratio is greater than 65%, propene yield 31%, yield of ethene about 6%.But catalyst stability is bad.

The following discloses document also is to have investigated the upward reactivity worth of butylene cracking system propylene of various element modified HZSM-5 such as metal ion, P modification.

Applied Catalysis A:General 31 (1995) 121～133, Journal of Catalysis 168 (1997): 349～363, Catalysis Letters 2002; 84 (3/4): 259～264, Journal of Chemical Physics 2003; 119 (18): 9765～9770, Catalysis Letters 2004 (97): 31～36, Industrial Catalysis 2004; 12 (10): 5～7, the catalysis journal 2004; 25 (1): 3～4, the catalysis journal 2005; 26 (12): 1083～1087, Applied Catalysis A:General 302 (2006) 69～77, Microporous and Mesoporous Materials 2007 (104): 129～136, Journal of Catalysis228 (2004) 234～242, Journal of Molecular Catalysis A:Chemical 237 (2005) 36～44, Catalysis Today 107-108 (2005) 663～670, Microporous and Mesoporous Materials 2006 (95): 296～305, Journal of Catalysis 237 (2006): 267～277, Journal of Rare Earths 2007; 25 (3): 321～328, Journal of Catalysis 248 (2007): 20～28, Journal of Catalysis 248 (2007): 29～37, Industrial Catalysis 2007; 15 (3): 30～34, rare earth 2008; 29 (5): 30～35, Catalysis Letters 2008 (125): 380-385, Applied Catalysis A:General 340 (2008) 176～182, Journal of Porous Materials 2008; 15 (2): 213～220, Journal of Catalysis 254 (2008): 180～189, Chinese Rare Earths 2008; 29 (5): 30～35, Applied Catalysis A:General 362 (2009) 26～33, Applied Catalysis A:General 352 (2009) (1/2): 87～94, Catalysis Surveys Asia2009 (13): 1～8, Catalysis Communications (2009), Journal of Molecular Catalysis A:Chemical 327 (2010) 12～19, Korean journal of chemical engineering 2010; 27 (3): 812～815, The Journal of Physical Chemistry C 2010; 114 (13): 5975-5984, Journal of Molecular Catalysis 2009; 23 (1): 11～16, oil and gas chemical industry 2010; 39 (2): 108～111, Journal of Molecular Catalysis 2010; 24 (3): 208～216, Catalysis Today 164 (2011) 154～157, petroleum refining and chemical industry 2011,42 (3): 42～46.

In sum, the ZSM-5 behind phosphorus modification, alkali metals modified, transition metal and rare metal, the modified with noble metals has activity and purpose selectivity of product preferably.But, exist high-temperature hydrothermal stability poor, along with also can making the duct part of catalyst, the adding of modifying element stops up, and catalyst is prone to the carbon distribution inactivation, and reaction stability still can not reach ideal effect; In addition, adding modifying element obviously increases processing step, has improved production and application cost.Nano molecular sieve and little crystal grain zeolite molecular sieve parent have anti-carbon deactivation preferably, but its acidity are still very strong, must could obtain purpose selectivity of product preferably through modification.Aspect the molecular sieve parent, the silica-rich zeolite molecular sieve is also used in former studies work emphatically.

Open source literature petrochemical industry 2004; 33 (4): 320～324, petrochemical industry 2005; 34 (1): 9～13, petroleum refining and chemical industry 2005; 36 (2): 33～37, petroleum refining and chemical industry 2005,36 (8): 44～48, Chemical Reaction Engineering and technology 2005,21 (2): 158～161, the catalysis journal 2005; 26 (2): 111～117, Chemical Engineering Journal2006; (116): 155～161, Journal of Molecular Catalysis 2011,25 (1): 69～77 have studied heating power and the mechanism of C 4 olefin in the reaction of ZSM-5 molecular sieve catalytic cracking system propylene/ethylene, point out to react should under high-temperature low-pressure, carry out, the reaction mechanism mechanism of reaction that the butylene cracking process mainly experiences isomerization, polymerization, cracking.

Therefore, except molecular sieve catalyst itself is carried out a series of modifications, reach and improve outside selectivity of light olefin and the yield, change process conditions, type of reactor also are the methods of using always.

Patent CN1611470A (2005) has disclosed a kind of method of producing propylene.Its technical characterictic is: in raw material, add carrier gas, improved the stability of catalyst.With silica alumina ratio is that 100～1000 ZSM type molecular sieve is a catalyst, and material carbon four and above alkene thereof are that 500～700 ℃, reaction pressure are 0～0.15MPa, weight (hourly) space velocity (WHSV) 0.5～30h in reaction temperature ^-1Under the condition, wherein the raw material adding is selected from N ₂, He, Ar, CH ₄, C ₂H ₆, C ₃H ₈Or C ₄H ₁₀In at least a carrier gas, and to make the mol ratio of carrier gas and raw material hydrocarbon be to react for 0.1～10 time, propene yield reaches about 30%.

Patent CN101045665A (2007), CN101045666A (2007), CN1915932 (2007) WO2007019787A1 (2007), CN20051028810 (2008), CN101450883A (2009), US2009105512A1 (2009), US7875756B2 (2011) have disclosed the rich olefins mixture that uses one or more carbon four or above alkene is produced propylene and ethene under condition of negative pressure as raw material method respectively.Its technical characterictic is: (under 0.09～0MPa), reaction temperature is 400～650 ℃, mass space velocity 1～12h in negative pressure ^-1Catalytic pyrolysis butylene under the condition, propylene and ethylene yield reach 60%; Though the negative pressure effect is better, its requirement to equipment is harsh.

Patent CN1915929A (2007) discloses a kind of explained hereafter cyclopropene method that adopts the multistage beds.Its technical characterictic is: carbon four and above olefin feedstock thereof be through comprising the fixed bed reactors of two-stage catalytic agent bed at least, is at least 10 ZSM-5 molecular sieve catalyst with silica alumina ratio and contacts and produce propylene.

Patent CN1915923A (2007) has disclosed a kind of C4～C12 olefins by catalytic cracking and has prepared the method for propylene.Its technical characterictic is: in reaction process, add an olefin oligomerization device; Pass through oligomerisation reaction to uncracked C 4 olefin in the product; Main production carbon eight alkene, and butane is not participated in oligomerisation reaction, carries out separating of butane and alkene through simple cooling; What oligomerisation reaction obtained is that master's olefin product turns back to alkene cracking reactor again with carbon eight alkene.

Following patent has been introduced under the different type of reactor and process conditions, the method for carbon four and above olefin catalytic cracking to produce propylene thereof.

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Can see from above-mentioned document: through changing the method for producing low-carbon alkene by catalytic pyrolysis such as process conditions or reactor, though can improve purpose product selectivity and yield to a certain extent.But, no matter being selected at the method that adds carrier gas in the raw material, adopts operation of high temperature condition of negative pressure or multistage reactor, they all can increase the complexity of equipment, increase cost, are unfavorable for commercial Application.

In sum: at present, mainly be to select the ZSM-5 zeolite molecular sieve for use in the catalyst in the C _ 4 alkene catalytic pyrolysis producing light olefins.But because the ZSM-5 molecular sieve has stronger acidity; And the acidity a little less than needing in the reaction of olefins by catalytic cracking production low-carbon alkene; Various processing such as steam passivation, acid treatment must be carried out to the ZSM-5 parent before use for this reason, also various element modified processing such as corresponding metal modification, phosphorus modification need be carried out subsequently it.However, the reaction result of butylene preparing propylene by catalytic cracking and ethene is unsatisfactory at present, and the conversion ratio of general butylene is 60～80%, and the overall selectivity of propylene and ethene is all not high.And the modification of preliminary treatment such as the high-temperature water vapor passivation that catalyst Precursors is carried out, acid treatment and various complicacies but can increase catalyst production cost undoubtedly.In addition, obtaining higher propylene and ethylene yield and selectivity 50～70% o'clock, reaction needs feeds carrier gas such as water vapour or needs to adopt harsh conditions such as negative pressure.With water is that diluent is relatively simple method, still, the existence of big water gaging in the reaction, the meeting accelerator activator is wearing out of nano molecular sieve catalyst especially, uses totally unfavorable for a long time.

Summary of the invention

The invention provides a kind of method of new olefin cracking system propylene.Why olefin cracking system propylene technology need carry out the modification processing of superheated vapor passivation and various complicacies to catalyst in the past; And need in reaction, utilize diluent gas such as negative pressure or use water vapour; Mainly be because the molecular sieve parent acidity of controlling catalyst is too strong, hydrogen migration and aromatisation side reaction are difficult to eliminate.We find when preparing catalyst with the ZSM-5 nucleus; Only has the weak acid center on the catalyst; And the grain size of catalyst is extremely small; Thereby in the olefin cracking reaction, having the intrinsic inhibition hydrogen migration and the effect of aromatisation side reaction, catalyst does not need complicated modification to handle without the water vapour passivation yet; Need not utilize condition of negative pressure in the reaction, need not use carrier gas such as water vapour yet, just can reach good propylene selectivity and productive rate.This thought obviously can be extended to molecular sieve ZSM-11, ZSM-12, ZSM-23, ZSM-35, ZSM-38, MCM-22, MCM-49, MCM-56 etc. and other molecular sieve with catalytic pyrolysis performance of having reported, but the ZSM-5 nucleus is best suited for.

As everyone knows, the acidity of zeolite molecular sieve is relevant with silica alumina ratio.The variation of silica alumina ratio can cause the acidity change of molecular sieve accordingly.The Al atom content is higher relatively in the low silica-alumina ratio zeolite molecular sieve, and acidic aluminum ol group content is higher relatively, and the acid site density of molecular sieve is high; But owing to silicon, aluminium electronegativity difference, the electronegativity of the anion frame of low silica-alumina ratio molecular sieve is little, and is little to proton polarization power, so the acid site is on the weak side.The acid site density of the zeolite molecular sieve of high silica alumina ratio is low, and the acid amount is few, but acid strength is strong partially.Generally speaking, ZSM-5 belongs to silica-rich zeolite, and when its silica alumina ratio changed in relative broad range, molecular sieve all had than highly acid, and this also is the reason that the ZSM-5 molecular sieve in use must modification.

The acidity of zeolite molecular sieve is also relevant with crystallite dimension.It is acid strong to be positioned near the ol group in ZSM-5 3 D pore canal crosspoint, and is positioned at a little less than the acidity in molecular sieve outer surface or aperture.Reduce the zeolite crystal size, make increasing strong acid point be exposed to aperture or outer surface, reduce near acid site, crosspoint, duct, can make the acid strength reduction of molecular sieve and be tending towards homogenising.Prepare catalytic cracking catalyst with the ZSM-5 nucleus and just be based on this understanding.The ZSM-5 nucleus is different from small-grain ZSM-5, also is different from nano-ZSM-5.Briefly, the ZSM-5 nucleus is not a crystal, is some structure cells, and its X-ray polycrystal powder diffraction maximum is extremely faint, and structure does not have the long-range order degree.By contrast, although nano-ZSM-5 crystal grain is very little, its structure has had the long-range order degree.Therefore, has strong X-ray polycrystal powder diffraction maximum.The difference of ZSM-5 nucleus and nano-ZSM-5 can be from Fig. 1-X-ray polycrystal powder diffraction pattern and Fig. 2-NH ₃Know among the acid figure of-TPD and find out.

Catalytic cracking for producing propylene using must be through polymerization-cracking process on the ZSM-5 catalyst for butylene, and such reaction mainly occurs in the weak acid position of catalyst.The c h bond type reaction that hydrogen migration and dehydroaromatizationof generate alkane and aromatic hydrocarbons is to influence optionally key factor of purpose product propylene, and this type of reaction mainly occurs in stronger acid position.Therefore can suppress the side reaction of c h bond type through reducing catalyst acidity, improve purpose product productive rate and selectivity.From NH ₃Can see obviously among the-TPD acid characterization figure that the intrinsic weak acid intensity of ZSM-5 nucleus suits and is evenly distributed, its n-hexane/cyclohexane adsorbance is different from nano-ZSM-5.So ZSM-5 nucleus olefins by catalytic cracking preferably.

The technical scheme that the present invention adopts is following:

The first step: synthetic ZSM-5 molecular sieve nucleus

At first, silicon source, crystal seed and deionized water are made into glue A,, then, under strong agitation, solution B are slowly joined and be made into even gel among the glue A aluminium source and inorganic acid or alkali, deionized water wiring solution-forming B.Each component by the mol ratio of its oxide is in this gel: M ₂O (alkali metal oxide): Al ₂O ₃: SiO ₂: H ₂O=3-12: 1: 20-800: 100-900; The crystal seed addition is not more than butt total amount 10% in the mixture gel; When preparation glue A, can select to use template, template used dose and SiO ₂Mol ratio is not more than 10.

Any or its any mixture in the optional silicic acid in said silicon source, white carbon, Ludox, waterglass, ethyl orthosilicate, the sodium metasilicate etc.; Any or its any mixture in the optional boehmite in aluminium source, sodium aluminate, aluminum sulfate, aluminum nitrate, the sodium metaaluminate etc.; Any or its any mixture among the optional NaOH of alkali source, the KOH etc.; Any or its mixture in the optional sulfuric acid of acid, nitric acid, phosphoric acid, the hydrochloric acid etc.; Template is n-butylamine, ethylenediamine, ethamine, 4-propyl bromide, TPAOH, propylamine, 1, any or its any mixture in the 6-hexamethylene diamine etc.

With gel hydrothermal crystallizing under static state or dynamic condition of gained, when crystallization finishes induction period, stop crystallization.The crystallization temperature scope is 50-200 ℃, and preferred 80-170 ℃, the crystallization time scope is 10min～500h, preferred 30min～24h.Crystallization is cooled to room temperature and drives still after accomplishing, and filters to obtain solid product.Solid product is handled through washing, drying and high-temperature roasting method, obtains ZSM-5 nucleus product.

The crystallization process of ZSM-5 zeolite generally can be divided into induction period and two stages of crystallization phase.Gel forms nucleus in induction period, grows into crystal fast at the interim nucleus of crystallization, and two stages constitute S type crystallization curve.The synthetic key of ZSM-5 nucleus is the coupling of crystallization temperature and crystallization time.When crystallization temperature was high, crystallization was short induction period; When crystallization temperature was low, crystallization was long induction period.Therefore, when crystallization temperature was high, the crystallization time of selecting for use will be lacked; When crystallization temperature was low, the crystallization time of selecting for use can prolong accordingly.Turning point in following induction period of different situations and crystallization phase will be confirmed by experiment.

In fact, the synthetic of ZSM-5 nucleus also can adopt the prescription in disclosed patent and the document to carry out.Like patent US3702886 (1972); US3941871 (1976); US4061724 (1977); US4166099 (1979); US4257885 (1981); EP0098641A2 (1984); US4526879 (1985); US4565681 (1986); CN85100463B (1988); CN85100463A (1989); US5240892 (1993); CN1086792A (1994); CN1219571A (1999); CN1056818C (2000); WO0138224A (2001); CN1088406C (2002); CN1417116A (2003); CN1530323A (2004); CN1699173A (2005); CN1715186A (2006); CN1307102C (2007); CN101279746A (2008); CN101559955A (2009); CN101428818B (2010); CN101993091A (2011).According to the preparation gel method of reporting in these existing open source literatures and the patent, carry out the synthetic of ZSM-5 nucleus product according to the crystallization condition of recommending in the above-mentioned steps again.

Second step: ZSM-5 nucleus powder product is prepared into catalytic cracking catalyst

Extruded moulding: ZSM-5 nucleus powder product, aluminium oxide and sesbania powder are mixed by suitable butt proportioning, with salpeter solution mixture is mixed then and pinch evenly, extruded moulding carries out drying, roasting to shaped article at last again.Aluminium oxide is got 30%～80% of total butt, and the sesbania powder is got total butt 0～10%; The salpeter solution volumetric concentration is 5%～20%; Baking temperature is 50～200 ℃, and be 3～20h drying time, and sintering temperature is 400～700 ℃, and roasting time is 1～10h.

The assay method of the butt that relates in this programme is: get a certain amount of powder sample high-temperature roasting certain hour in Muffle furnace; Powder quality ratio is the contents on dry basis of sample before powder quality after the roasting and the roasting; Sintering temperature is 600 ℃, and roasting time is 2～3h.In addition, the key of extrusion is the mechanical strength that guarantees catalyst in this programme, and desired strength is not less than 10N/cm.The mensuration of mechanical strength adopts ZQJ-II intelligence granule strength testing machine to carry out.

Ammonium exchange:, under suitable temperature, carry out ion-exchange with ammonium salt solution with baked shaped article; Spend deionised water then; Obtain hydrogen type catalyst through dry, roasting again.Ammonium exchange process major control Na ⁺Content makes it can not be higher than 0.2%.Described ammonium salt can be any in ammonium nitrate, ammonium chloride, the ammonium carbonate etc., and ammonium salt solution concentration is 0.05～1.0mol/L, and the liquid-solid volume ratio of ammonium salt solution and catalyst is 1: 1～20: 1, preferred 3: 1～10: 1; The exchange temperature is 20～80 ℃, preferred 20～60 ℃; Swap time 10min～100h, preferred 30min～4h; Exchange number of times 1～5 time.The baking temperature of ammonium exchange selects 80～200 ℃, drying time 1～100h; NH ₄ ⁺→ NH ₃+ H ⁺Middle NH ₃With proton H ⁺Between strong complexing power, require thorough roasting, so sintering temperature selects 300～700 ℃, preferred 400～600 ℃; Roasting time is 4～20h, preferred 3～8h.

Said Na ⁺The Determination on content method can adopt flame photometer, and Inductively Coupled Plasma (ICP) measures.The engineer who is familiar with this area can carry out Na with reference to specification ⁺Measure.

Acid reaming:, under conditions such as suitable acid concentration and temperature, carry out sour reaming and handle with the hydrogen type catalyst after the above-mentioned ammonium exchange; Spend deionised water then to neutral, carry out drying again, roasting obtains catalyst, and is subsequent use.

The optional HCl of described acid, HNO ₃, H ₂SO ₄Or any in the citric acid, preferred HNO ₃And citric acid.Because adopt HCl can introduce Cl, and H ₂SO ₄Decompose difficulty, be difficult for removing.Acid concentration is 0.05～6mol/L, the liquid-solid volume ratio of acid solution and catalyst 1: 1～20: 1, preferred 3: 1～10: 1; The acid reaming processing time is 30min～100h, preferred 1～5h; Treatment temperature is 20～80 ℃.Baking temperature is 50～200 ℃, and be 3～20h drying time, and sintering temperature selects 300～600 ℃, and roasting time is 1～4h.

The purpose of sour reaming is to remove the inner amorphous barrier of ZSM-5 nucleus in this programme, increases the diffusion rate in duct.In fact, the hydrogen type catalyst that obtains after the ammonium exchange can directly be used for the reaction of preparing propylene by catalytic cracking olefin.But sour reaming is favourable to improving activity of such catalysts.So far, accomplished preparing propylene by catalytic cracking Preparation of catalysts among the present invention.

ZSM-5 nucleus catalyst cracking olefin with preparation is produced propylene and isobutene, and raw material can be the C 4 fraction of taking out excess, methanol-to-olefins by-product, the alkene in the catalytic cracking light petrol (C5～C8) or the C4～C5 alkene in other oil refining and the PETROLEUM PROCESSING of butylene, c4 cleavage or the C5 in the hybrid C 4 behind mixed butene, the ether in the reaction.On fixed bed reactors, carry out catalytic cracking reaction, reaction temperature is 400～600 ℃, and reaction pressure is 0.01～0.1MPa, and weight space velocity is 1～100h ^-1, need not any carrier gas.Wherein, 450 ℃～500 ℃ of reaction temperatures, weight space velocity 3～20h ^-1Be the optimal conditions scope.

The present invention is applicable to that also this is in ZSM-23, ZSM-48, ZSM-12, MCM-22, MCM-56, MCM-49, ITQ-2 equimolecular sieve nucleus.These molecular sieve nucleus can adopt the prescription in disclosed patent and the document to carry out.Like CN1328960A (2002); CN1686801A (2005); CN101007637A (2007); CN101214971 (2008); CN101613114 (2009); CN101554592A (2009); CN101801848A (2010); CN10204023A (2010); CN101973560A (2011); Microporous and Mesoporous Materials 31 (1999) 241-251; Journal of Materials Chemistry 12 (2002) 369-373; Journal of Molecular Catalysis B:Enzymatic 22 (2003) 119-133; Journal of Catalysis 255 (2008) 68-78.The engineer who is familiar with this area all can adopt the technical method of reporting in existing open source literature and the patent, and the preparation gel then, carries out the synthetic of molecular sieve nucleus product according to the crystallization condition of recommending in the above-mentioned steps.Synthesizing can be by preparing catalyst and prepared catalyst is used for catalytic cracking reaction with top said method behind the said molecular sieve nucleus.

Beneficial effect of the present invention is; ZSM-5 nucleus catalyst itself only has the weak acid center, and crystal grain is extremely small, need not any modification handle; Must not adopt any negative pressure or carrier gas condition just can significantly suppress side reactions such as hydrogen migration aromatisation yet; Thereby improved purpose product selectivity and yield, made Deep Catalytic Cracking process simpler, catalyst is more cheap.

Description of drawings

Fig. 1 is the ZSM-5 nucleus that synthesizes in the embodiment of the invention 1 and the Comparative Examples and the X-ray polycrystalline diffraction comparison diagram of nano-ZSM-5 zeolite.Can see by Fig. 1: the ZSM-5 nucleus in 2 θ=7 °～9 ° and 22 °～25 ° characteristic diffraction peaks that the ZSM-5 molecular sieve occurs.

Fig. 2 is the ZSM-5 nucleus that synthesizes in the embodiment of the invention 1 and the Comparative Examples 1 and the acid comparison diagram of nano-ZSM-5.Can see by Fig. 2: at corresponding weak acid center, 150～350 ℃ of low temperature desorption districts, 350～600 ℃ of strong acid centers that high temperature desorption district is corresponding; Nano-ZSM-5 has typical two desorption peaks, and the ZSM-5 nucleus has only a weak acid desorption peaks.

The specific embodiment

Through following examples the present invention is further specified, but the present invention does not receive the restriction of these embodiment.

Comparative Examples

With reference to the report of publication CN1260126C, carry out the synthetic of ZSM-5 molecular sieve.Be about to waterglass, crystal seed, n-butylamine and deionized water and be made into glue A, then with aluminum sulfate solution, sodium chloride, deionized water and H ₂SO ₄Solution, the wiring solution-forming B that stirs then, slowly joins solution B under strong agitation and is mixed with the mixture gel in the A solution.Each component by the mol ratio of its oxide is in the gel:

Al ₂O ₃: SiO ₂: Na ₂O: n-C ₄H ₉NH ₂: NaCl: H ₂O=1.0: 31.2: 2.0: 12.2: 18: 833.3, adding the crystal seed amount was that mixture gel butt gross weight is 10.0%.The mixture gel is added in the agitated reactor, stir down and be warming up to 100 ℃ gradually, kept 24 hours; In 2 hours, be warming up to 170 ℃ again, kept 36 hours, reduce to normal temperature then; Filter, tell mother liquor, reactant obtains the white powder product through washing, drying and roasting.(XRD) is determined as the ZSM-5 zeolite molecular sieve through X-ray diffraction, records its crystal grain between 20～30nm with transmission electron microscope, belongs to nano-ZSM-5.

Extruded moulding: with the gained molecular sieve: aluminium oxide: it is even that the smart powder mass ratio in field equals 4: 6: 0.03 mixed, and using volumetric concentration is that 10% dilute nitric acid solution mixes it and pinches evenly extruded moulding again; Then with shaped article dry 12h, 500 ℃ of following roasting 3h under 110 ℃.

The ammonium exchange: with the ion-exchange of 0.2mol/L ammonium nitrate solution, the liquid-solid volume ratio of ammonium nitrate and catalyst is 3: 1, and 3h is handled in the ammonium exchange at ambient temperature, carries out twice continuously, spends deionised water then; Ammonium exchange back product is 100 ℃ of dry 12h down in temperature, and hydrogen type catalyst M-1 is promptly processed in 600 ℃ of following roastings 6 hours, and is subsequent use.

The acid reaming: with the hydrogen type catalyst M-1 that obtains after the ammonium exchange, using the dilute nitric acid solution of 0.6mol/L is 5: 1 by liquid-solid volume ratio, carries out sour reaming at ambient temperature; After 3h is handled in the acid reaming; Being washed with water to neutrality, is 100 ℃ of dry 12h down in temperature, and 540 ℃ of following roastings are after 6 hours; Process catalyst M-2, subsequent use.

On fixed bed reactors, be raw material with mixed c 4 liquefied gas behind the ether of catalytic cracking unit by-product, wherein raw material consists of: butene-1 (C ₄ ⁼-1) be 14.61%, along anti--butene-2 (C ₄ ⁼-2) be 34.37%, isobutene (i-C ₄ ⁼) be 0.037%, butane content is 50.34% (iso-butane i-C ₄ ⁰Be 37.96%, normal butane n-C ₄ ⁰Be 12.38%), residue 0.64% is propane and C ₅ ⁺Composition.Reaction pressure is a normal pressure, 450 ℃ of reaction temperatures, WHSV=3.85h ^-1Condition under, be that catalyst carries out the butylene catalytic cracking reaction with M-1 and M-2, it is 95.20% and 96.67% that butene conversion is respectively, productivity of propylene is respectively 4.57% and 4.60%.The isobutene yield is 1.52% and 2.10%.

Embodiment 1

Be about to waterglass, crystal seed, n-butylamine and deionized water and be made into glue A, then with aluminum sulfate solution, deionized water and H ₂SO ₄Solution, the wiring solution-forming B that stirs then, slowly joins solution B under strong agitation and is mixed with the mixture gel in the A solution.Each component by the mol ratio of its oxide is in the gel: Al ₂O ₃: SiO ₂: Na ₂O: n-C ₄H ₉NH ₂: H ₂O=1.0: 36.2: 2.0: 12.2: 850, the crystal seed addition is that mixture gel butt gross weight is 10.0%.Reaction mixture gel is added in the agitated reactor, stir down and be warming up to 110 ℃ gradually, keep 24h.Reduce to normal temperature then, filter, tell mother liquor, the white powder product that reactant obtains through washing, drying and roasting.Industry X-ray diffraction (XRD) is measured, the diffractive features peak with ZSM-5 molecular sieve, but its intensity very a little less than, promptly obtain the ZSM-5 nucleus.

The ammonium exchange: with the ion-exchange of 0.2mol/L ammonium nitrate solution, the liquid-solid volume ratio of ammonium nitrate and catalyst is 3: 1, and 3h is handled in the ammonium exchange at ambient temperature, carries out twice continuously, spends deionised water then; Ammonium exchange back product is 100 ℃ of dry 12h down in temperature, and hydrogen type catalyst A-1 is promptly processed in 600 ℃ of following roastings 6 hours, and is subsequent use.

The acid reaming: with the hydrogen type catalyst M-1 that obtains after the ammonium exchange, using the dilute nitric acid solution of 0.6mol/L is 5: 1 by liquid-solid volume ratio, carries out sour reaming at ambient temperature; After 3h is handled in the acid reaming; Being washed with water to neutrality, is 100 ℃ of dry 12h down in temperature, and 540 ℃ of following roastings are after 6 hours; Process catalyst A-2, subsequent use.

On fixed bed reactors, be raw material with mixed c 4 liquefied gas behind the ether of catalytic cracking unit by-product, wherein raw material consists of: butene-1 (C ₄ ⁼-1) be 14.61%, along anti--butene-2 (C ₄ ⁼-2) be 34.37%, isobutene (i-C ₄ ⁼) be 0.037%, butane content is 50.34% (iso-butane i-C ₄ ⁰Be 37.96%, normal butane n-C ₄ ⁰Be 12.38%), residue 0.64% is propane and C ₅ ⁺Composition.Reaction pressure is a normal pressure, 500 ℃ of reaction temperatures, WHSV=3.5h ^-1Condition under, be that catalyst carries out the butylene catalytic cracking reaction with A-1 and A-2, butene conversion is respectively 75.84% and 76.02%, productivity of propylene is respectively 34.98% and 35.33%, the isobutene yield is 11.60% and 12.65%.

Embodiment 2

Repeat embodiment 1, but change crystallization temperature into 120 ℃, 170 ℃, corresponding crystallization time is 18h, 0.5h.Then obtain ZSM-5 nucleus catalyst A-3, A-4.Reaction pressure is a normal pressure, 470 ℃ of reaction temperatures, WHSV=3.5h ^-1Condition under, its butene conversion is respectively 82.71% and 81.54%, propene yield respectively 27.60% and 26.48%, the isobutene yield is respectively 12.01% and 14.60%.

Embodiment 3～5

Repeat embodiment 1, but crystallization time is changed into 20h, 10h, 5h respectively.Then obtain ZSM-5 nucleus catalyst A-5, A-6, A-7.Its butene conversion is for being respectively 69.51%, 65.65% and 66.47%, and propene yield is respectively 33.40%, 32.60% and 30.26%, isobutene yield 10.45%, 9.75% and 11.03%.

Embodiment 6～8

Repeat embodiment 1, but the silica alumina ratio of molecular sieve is changed into 25,80,125 respectively.Then obtain ZSM-5 nucleus catalyst B-1, B-2, B-3.At normal pressure, reaction temperature is 470 ℃, WHSV=3.5h ^-1Condition under, its butene conversion is for being respectively 83.97%, 84.44% and 85.47%, propene yield is 24.04%, 23.56% and 22.87%, isobutene yield 10.96%, 9.32% and 11.65%.

Embodiment 9～12

Repeat embodiment 1, but the silicon source is changed into white carbon, Ludox, sodium metasilicate respectively.Then obtain ZSM-5 nucleus catalyst C-1, C-2, C-3.At normal pressure, reaction temperature is 470 ℃, WHSV=1.5h ^-1Condition under, its butene conversion is 84.48%, 83.92% and 84.20%, propene yield is 23.49%, 24.31% and 22.98%, isobutene yield 12.43%, 11.95% and 12.83%.

Embodiment 13～15

Repeat embodiment 1, but the change of aluminium source is respectively sodium metaaluminate, aluminum nitrate, sodium aluminate.Then obtain ZSM-5 nucleus catalyst D-1, D-2, D-3.At normal pressure, reaction temperature is 470 ℃, WHSV=5.0h ^-1Condition under, its butene conversion is 77.07%, 76.86% and 76.53%, propene yield is 22.88%, 22.50% and 21.33%, isobutene yield 14.26%, 14.56% and 15.30%.

Embodiment 16～18

Repeat embodiment 1, but behind the hydrogen type catalyst of ammonium exchange back system, using the rare nitric acid of 0.4mol/L is to carry out sour reaming under 25 ℃ in temperature, the processing time is respectively 4h, 8h, 12h, obtains catalyst and is designated as E-1, E-2, E-3.At normal pressure, reaction temperature is 470 ℃, WHSV=8.25h ^-1Condition under, its butene conversion is 80.70%, 81.20% and 82.65%, propene yield is 18.69%, 18.36% and 19.61%, isobutene yield 9.59%, 8.98% and 9.87%.

Embodiment 19

With mixed c 4 liquefied gas behind the ether is raw material, and its total butene content is 53%, wherein butene-1 (C ₄ ⁼-1) be 16.29%, along anti--butene-2 (C ₄ ⁼-2) be 33.81%, isobutene (i-C ₄ ⁼) be 2.96%, butane content is 45% (iso-butane i-C ₄ ⁰Be 34.96%, normal butane n-C ₄ ⁰Be 10.10%), residue 2% is propane and C ₅ ⁺Composition.Be catalyst with A-1, A-2, B-2, C-1, D-1, the E-1 for preparing in the foregoing description respectively, on fixed bed reactors, normal pressure, 470 ℃ of reaction temperatures, WHSV=3.5h ^-1React result such as following table under the condition:

The reactivity worth table of table 1 different catalysts

Catalyst	Conversion ratio (quality %)	Propene yield (quality %)	Isobutene yield (quality %)
				A-1	83.21	25.77	15.47
A-2	80.51	27.77	13.87
				B-2	75.45	28.40	10.63
C-1	81.54	27.50	9.78
				D-1	80.18	27.60	14.95
E-1	78.43	28.52	12.14

The adsorbance contrast of table 2 nano-ZSM-5 and nucleus phase ZSM-5

Sample	N-hexane adsorbance %	Cyclohexane adsorbance %	The duct restricted index
				Nano-ZSM-5	8.560	8.225	1.040
The ZSM-5 nucleus	4.690	8.020	0.585

Table 2 is the adsorbance contrast of Comparative Examples and embodiment gained catalyst, can see that there is significant difference in the duct restricted index of ZSM-5 nucleus and nano-ZSM-5, the duct restraining force of ZSM-5 nucleus very a little less than.

Claims

1. the method for a preparing propylene by catalytic cracking is characterized in that comprising the steps:

The first step, synthetic ZSM-5 molecular sieve nucleus: silicon source, crystal seed and deionized water are made into glue A; With aluminium source and inorganic acid or alkali, deionized water wiring solution-forming B; Stir down solution B slowly to be joined and be made into even gel among the glue A; Each component by the mol ratio of its oxide is in this gel: M ₂O (alkali metal oxide): Al ₂O ₃SiO ₂: H ₂O=3-12: 1: 20-800: 100-900; With the gel hydrothermal crystallizing, when crystallization finishes induction period, stop crystallization; Crystallization temperature is 50-200 ℃, and the crystallization time scope is 10min～500h; The crystal seed addition is not more than butt total amount 10% in the mixture gel;

Second step: the ZSM-5 nucleus is prepared into catalytic cracking catalyst: ZSM-5 nucleus, aluminium oxide and sesbania powder are mixed by the butt proportioning, with salpeter solution mixture is mixed then and pinch evenly, extruded moulding carries out drying, roasting to shaped article at last again; With baked shaped article, carry out ion-exchange with ammonium salt solution, spend deionised water then; Dry again, roasting obtains hydrogen type catalyst; Hydrogen type catalyst after the above-mentioned ammonium exchange is carried out sour reaming to be handled; Spend deionised water then to neutral, carry out drying again, roasting obtains catalyst.

2. method according to claim 1 is characterized in that, when preparation glue A, adds template, template and SiO ₂Mol ratio is not more than 10.

3. method according to claim 1; It is characterized in that; Alkali source selects any or its mixture among NaOH, the KOH; A kind of or its mixture in sulfuric acid, nitric acid, phosphoric acid, the hydrochloric acid is selected in acid, and template is n-butylamine, ethylenediamine, ethamine, 4-propyl bromide, TPAOH, propylamine, 1, a kind of or its mixture in the 6-hexamethylene diamine.

4. method according to claim 1 is characterized in that, the crystallization temperature scope is 80-170 ℃, and the crystallization time scope is 30min～24h.

5. method according to claim 1 is characterized in that aluminium oxide is got 30%～80% of total butt when extruded moulding, and the sesbania powder is got total butt 0～10%; The salpeter solution volumetric concentration is 5%～20%; Baking temperature is 50～200 ℃, and be 3～20h drying time, and sintering temperature is 400～700 ℃, and roasting time is 1～10h.

6. method according to claim 1, it is characterized in that the condition of ammonium exchange is following: the liquid-solid volume ratio of ammonium salt solution and catalyst is 1: 1～20: 1; The exchange temperature is 20～80 ℃; Swap time 10min～100h; Exchange number of times 1～5 time.

7. method according to claim 5, it is characterized in that the condition of ammonium exchange is following: the liquid-solid volume ratio of ammonium salt solution and catalyst is 3: 1～10: 1; The exchange temperature is 20～60 ℃; Swap time 30min～4h.

8. the catalyst of claim 1,2,3,4,5,6 or 7 said method preparations is used to produce propylene and isobutene; It is characterized in that raw material is the C 4 fraction of taking out excess, methanol-to-olefins by-product, the C5 in the catalytic cracking light petrol～C8 alkene or the C4～C5 alkene of butylene, c4 cleavage or the C5 in the hybrid C 4 behind mixed butene, the ether in the reaction; On fixed bed reactors, carry out catalytic cracking reaction, reaction temperature is 400～600 ℃, and reaction pressure is 0.01～0.1MPa, and weight space velocity is 1～100h ^-1, without carrier gas.

9. method according to claim 8 is characterized in that, 450 ℃～500 ℃ of reaction temperatures, weight space velocity 3～20h ^-1