CN107266280B

CN107266280B - Method and system for preparing low-carbon olefin from oxygen-containing compound

Info

Publication number: CN107266280B
Application number: CN201610211423.7A
Authority: CN
Inventors: 崔守业; 于敬川; 王新
Original assignee: Sinopec Research Institute of Petroleum Processing; China Petroleum and Chemical Corp
Current assignee: Sinopec Research Institute of Petroleum Processing; China Petroleum and Chemical Corp
Priority date: 2016-04-06
Filing date: 2016-04-06
Publication date: 2020-03-24
Anticipated expiration: 2036-04-06
Also published as: CN107266280A

Abstract

The invention discloses a method and a system for preparing low-carbon olefin by using oxygen-containing compounds, wherein the method comprises the following steps: a. feeding the raw material containing the oxygen-containing compound into a reactor to contact with the mixed catalyst from the catalyst tank, and performing dehydration to prepare olefin for reaction to generate oil gas rich in low-carbon olefin and spent catalyst; b. leading out the spent catalyst from the reactor, conveying the spent catalyst to a catalyst tank, and mixing the spent catalyst with the regenerated catalyst from the regenerator to obtain a mixed catalyst; c. conveying part of the mixed catalyst obtained in the step b to a reactor to contact with a raw material containing an oxygen-containing compound and carrying out dehydration to prepare olefin reaction, conveying the other part of the mixed catalyst obtained in the step b to a regenerator and carrying out scorching regeneration in an oxygen-containing atmosphere, and separating to obtain a regenerated catalyst and regenerated flue gas; d. and c, conveying the regenerated catalyst obtained in the step c to a catalyst tank. The method and the system can provide the catalyst of the required carbon deposition for the reaction of preparing the low-carbon olefin by the oxygen-containing compound.

Description

Method and system for preparing low-carbon olefin from oxygen-containing compound

Technical Field

The invention relates to a method and a system for preparing low-carbon olefin from oxygen-containing compounds.

Background

Lower olefins (C)₂-C₄Olefins) have been the dominant primary organic chemicals in the modern petroleum and chemical industries, especially ethylene and propylene. The methods for producing light olefins can be broadly divided into two major categories, namely the traditional petroleum route and the emerging non-petroleum route. The traditional method for preparing low-carbon olefin by petroleum route mainly comprises steam cracking and catalytic cracking process production. Since the 10 s in the 20 th century, various countries in the world have been dedicated to developing routes for preparing low-carbon olefins from non-petroleum resources, and some progress has been made.

At present, the catalyst for preparing low-carbon olefin by using oxygen-containing compound generally contains molecular sieve such as ZSM-5 and SAPO, etc. Chinese patent CN1359753A discloses a metalloaluminophosphate molecular sieve and a method for converting methanol to olefin using the same, wherein the catalyst used in the patent is O having an empirical formula (ELxAlyPz)₂Wherein EL is a metal, such as silicon or magnesium, and x, y and z are the mole fractions of EL, Al and P, respectively. The molecular sieve is predominantly a plate-like crystalline structure with an average smallest crystal size of at least 0.1 micron and an aspect ratio (aspect ratio) of no greater than 5. The products obtained using this catalyst contain a relatively high amount of ethylene (relative to propylene).

Chinese patent CN1084431A discloses a catalyst and reaction process for converting methanol into light olefin, wherein a ZSM-5 type zeolite catalyst containing phosphorus, rare earth elements and pore structure regulator and a reaction process of a multistage adiabatic fixed bed cracking reactor using a dehydration reactor and 2-n reaction-regeneration switching operations are used to perform non-cyclic operation at high temperature (> 400 ℃), and the catalyst has high activity, high selectivity, high water resistance, thermal stability and long reaction life. On a plant scale of 0.7 to 1 ton of methanol per day, the methanol conversion is 100%, C₂-C₄The olefin selectivity can be greater than 85%, the on-line run time can be greater than 600 hours,and the single pass operating period may be greater than 24 hours. However, because the heat transfer of the fixed bed reactor is slow, the reaction of preparing light olefins from methanol is a strong exothermic reaction, and hot spots are easy to occur, so that the device is damaged.

Chinese patent CN101318868A discloses a method and apparatus for producing low-carbon olefins from oxygen-containing compounds, which solves the problem in the prior art that the temperature of the reactor cannot be flexibly controlled. The technical scheme is as follows: the reaction product material flow enters a quenching system after heat exchange with the oxygen-containing compound raw material through a heat exchanger, the oxygen-containing compound raw material after heat exchange enters a cooling heat exchanger to adjust the temperature and then enters a reactor, and a heat taking cooler is arranged in the reactor to take out the excess reaction heat in the reactor. The method can realize flexible control of the reaction temperature of the reactor and greatly reduce the abrasion degree of the catalyst in a heat taking facility.

Chinese patent CN101270020A discloses a method for producing low-carbon olefin from methanol, which mainly solves the problem of low selectivity of target products in the process of preparing low-carbon olefin from methanol. The method comprises the following steps: (a) heating an oxygen-containing compound raw material containing methanol at a reaction temperature of 300-600 ℃ at a raw material weight hourly space velocity of the oxygen-containing compound of 1-50 hours^-1Under the condition that the reaction pressure (gauge pressure) is 0.05-10 MPa, the raw materials are contacted with a silicoaluminophosphate molecular sieve catalyst in a reactor; (b) separating the catalyst from the reaction products; (c) exchanging heat between the reaction product and the raw material containing the methanol, and heating the raw material containing the methanol to 100-350 ℃ under the condition of ensuring effective recovery of heat of the reaction product; (d) the technical scheme of (a) to (c) is repeated, so that the problem is solved well, and the method can be used for industrial production of low-carbon olefin.

Chinese patent CN1617842A discloses a process for the preparation of an olefin product from an oxygenate feedstock comprising: a) contacting a feedstock in a reaction zone with a catalyst comprising i) a molecular sieve having a defined opening size and ii) a CO oxidation metal at a reaction pressure of from 0.1kPa to 100MPa under conditions effective to convert the feedstock to an olefin product stream comprising C2 to C3 olefins and to form carbonaceous deposits on the catalyst to provide a carbonaceous catalyst; b) contacting at least a portion of the carbonaceous catalyst with a regeneration medium comprising oxygen in a regeneration zone comprising a fluidized bed regenerator having a dense fluid phase and a dilute fluid phase under conditions effective to obtain a regenerated catalyst portion, wherein the difference between the temperature of the dilute phase and the temperature of the dense phase is no greater than 100 ℃; c) introducing the regenerated catalyst portion to the reaction zone; and d) repeating steps a) -c).

Patent WO2006049864 discloses a process and corresponding apparatus for producing light olefins from oxygenates, wherein the process comprises feeding an oxygenate feed stream through a feed stream distributor (3) into an OTO reactor; contacting the oxygenate with a catalyst to produce a mixture comprising light olefins, unreacted oxygenate, and other by-products; separating unreacted oxygenate and diolefins from said light olefins and said by-products; and returning unreacted oxygenate and diolefins to the OTO reactor. Unreacted oxygenate and diolefins are fed to the reactor through at least one feed nozzle at a point separate from the oxygenate feed stream. The process is believed to be able to carry out the oxygenate conversion over a wide range of pressures (10.1kPa to 10.1MPa), but not all pressures give good results, preferably from 101.3kPa to 1013.3 kPa.

Chinese patent CN101544529A discloses a pretreatment method and equipment for reaction product gas in a process of preparing olefin from oxygen-containing compound, which aims to solve the defects that the reaction product gas in the prior art for preparing olefin from oxygen-containing compound has high temperature and contains a small amount of catalyst. The method comprises the steps of enabling reaction generated gas in the process of preparing olefin from oxygen-containing compounds to enter a quenching tower after heat exchange, washing a catalyst carried in the reaction generated gas, reducing the temperature of the reaction generated gas, enabling the reaction generated gas to enter a water washing tower, further washing the catalyst carried in the reaction generated gas, and sending the catalyst to an olefin separation unit. The invention also discloses equipment consisting of the quenching tower and the water washing tower, wherein the quenching tower is internally provided with an empty tower or a baffle or a tray, the water washing tower is internally provided with a baffle, a filler or a tray, and the bottom of the water washing tower is provided with an oil separation facility.

Because the reaction process of preparing the low-carbon olefin from the oxygen-containing compound is an exothermic reaction, if pure methanol is used for feeding, the total reaction heat of the methanol-to-olefin is generally 20-35 KJ/mol, the adiabatic temperature rise is above 200 ℃ at a small water-alcohol ratio, and if a side reaction in the MTO reaction process is considered, the adiabatic temperature rise is larger. Such high temperature rise not only affects the MTO reaction result and accelerates the carbon deposition rate of the catalyst, but also needs to consider the hydrothermal stability of the catalyst. Therefore, to reduce the temperature rise in the reactor, measures such as designing a heat removal system, reducing the initial composition of reactants, and reducing the temperature of the feed are generally required.

Chinese patent CN102951982A discloses a method for reducing energy consumption of an apparatus for producing olefin from oxygen-containing compound. Preheating a liquid oxygen-containing compound raw material to a certain temperature by a raw material preheater, dividing the raw material into two parts, and heating and gasifying one part by a raw material vaporizer to obtain a gas-phase raw material; the other is atomized into atomized liquid phase raw material; mixing a gas-phase raw material and an atomized liquid-phase raw material in front of a raw material/reaction gas heat exchanger, feeding the mixture into the raw material/reaction gas heat exchanger in a mist flow mode, fully exchanging heat with oil gas generated by high-temperature reaction from a reactor to recover high-temperature-level heat of the oil gas generated by the high-temperature reaction, completely gasifying the raw material after recovering the high-temperature-level heat to form high-temperature gasification raw material gas, and feeding the high-temperature gasification raw material gas into the reactor for reaction; oil gas generated by high-temperature reaction from the reactor is sent to a rear quenching water washing system after heat exchange of the raw material/reaction gas heat exchanger. The method can effectively improve the heat exchange effect of the heat exchanger, reduce the volume of the heat exchanger and reduce the energy consumption of the device, but the method does not solve the problem of cooling the reaction catalyst.

US patent US09401078 discloses a process for converting methanol or dimethyl ether into olefins. The process comprises the step of contacting a methanol or dimethyl ether containing material with a catalyst comprising a zeolite having 10-membered ring cross channels, such as ZSM-5, and a diffusion parameter for 2, 2-dimethylbutane of less than 100 seconds when measured at 120 ℃ and a 2, 2-dimethylbutane pressure of 60 torr (8kPa)^-1. The contacting step is carried out at a temperature of 370-480 ℃, a methanol partial pressure of 30-150 psia, and a methanol per pass conversion of less than 95%.

US patent US09378416 discloses a fast fluidized bed reactor for MTO process, which has an upper settling zone and a lower reaction zone, wherein the MTO process is carried out in a dense phase zone of the lower reaction zone and a transition zone connecting the settling zone, wherein the feedstock is partially converted to lower olefins in the presence of a diluent by passing through the dense phase zone containing a non-molecular sieve catalyst, and then completely converted by passing through the transition zone at the upper part of the dense phase zone. A portion of the catalyst is discharged from the settling zone and a small portion is regenerated and then returned to the upper portion of the dense phase zone while the catalyst is continuously recycled from the settling zone back to the bottom reaction zone. The process and apparatus provide a process that is effective in reducing catalyst inventory as compared to conventional bubble column reactors.

US09887860 discloses a process for producing olefins from an oxygenate feedstock which employs a SAPO molecular sieve catalyst to produce ethylene and propylene. A feedstock comprising an oxygenate contacts a SAPO molecular sieve catalyst in a fluidized bed reactor comprising at least a reaction zone and a circulation zone to produce an olefin product.

U.S. patent No. 7038102 discloses a process for capturing catalyst fines from a quenched effluent reaction product gas stream from an oxygenate to olefin conversion process by contacting the gas stream with a liquid, including a liquid having a low level of catalyst fines, such as an oxygenate feedstock or stripped and/or filtered oxygenate to olefin by-product water, to remove catalyst fines from the quenched gaseous effluent to address corrosion and plugging of downstream equipment by reaction oil and gas carried fines.

Chinese patent CN101384685A provides a method for limiting the loss of catalyst particles through the olefin product stream and the regenerator flue gas stream exiting the reaction system. In particular, the invention provides a process for removing catalyst particles from a reactor using a water stream and from a regenerator using a two-step separation process comprising the use of a catalyst fines separation unit.

At present, the reactors adopted by the technology for preparing low-carbon olefin by using oxygen-containing compounds mainly comprise a fixed fluidized bed reactor, a dense-phase fluidized bed reactor and the like. The bed layer of the fixed bed reactor has poor heat transfer effect, and for strong exothermic reaction, if the heat released in the reaction process can not be transferred out in time, hot spots are easy to appear,the problem of temperature runaway and the like, and the replacement and regeneration of the catalyst are relatively troublesome. The diameter and height of the fixed bed reactor are not strictly limited, but the height/diameter ratio adopted by the reactor design is 2.5-12 in consideration of the factors of fluid distribution, manufacturing cost, safety and the like. The fixed bed reactor is also adopted in the early catalytic cracking reaction, carbon deposition can occur on the catalyst in the catalytic cracking reaction, and the regeneration reaction is needed to recover the activity of the catalyst, so that the fixed bed reactor is needed to be discontinuously used for reaction and regeneration, and at least more than three reactors are needed to ensure the continuity of continuous feeding and other operations. The dense-phase fluidized bed reactor belongs to the category of bubbling bed and turbulent bed, and its empty tower linear speed is generally 0.2-1.5 m/s, and space velocity is 2-10h^-1The reaction residence time is therefore generally relatively long, and owing to the low linear velocity of the dense-phase fluidized-bed reactor, backmixing tends to occur, which affects the product distribution and quality, on the other hand the diameter of the reactor is relatively large. Generally, the reaction of the technology for preparing low-carbon olefin from oxygen-containing compound is considered to be the reaction with increased molecular number, the low reaction pressure is favorable for chemical equilibrium to proceed towards the direction of generating low-carbon olefin, and in consideration of engineering factors, the domestic and foreign MTO technology still adopts a similar catalytic cracking process flow, the reactor adopts a dense-phase fluidized bed reactor, the reaction pressure is also similar to the catalytic cracking process, namely 0.1-0.3 Mpa (gauge pressure), but the problem brought is that the size of the reactor is overlarge. For example, because the existing MTO unit employs a cyclone separator similar to catalytic cracking, the natural loss of the catalyst during the production process is inevitable, and especially when the catalyst has more fine catalyst powder with the particle size less than or equal to 20 μm, the subsequent product separation is adversely affected, and the catalyst is also disadvantageously reused. In addition, the retention time of the generated olefin in the reactor is long, the hydrogen transfer reaction is increased, and the method is also very unfavorable for the high yield of the low-carbon olefin.

Although it was previously thought that low pressure favours the molecular build-up reaction, for example, patents CN1321953 and WO2006049864 disclose reaction pressures up to 100MPa, which employ a reaction regeneration scheme still similar to conventional FCC catalyst circulation systems, with the catalyst flow being controlled by differential pressure between reaction and regeneration.

The linear velocity of the riser reactor is relatively high, for example, the linear velocity of an inlet of an equal-diameter riser reactor of a catalytic cracking device is generally 4-7 m/s, the linear velocity of an outlet is 12-18 m/s along with the progress of a cracking reaction, the reaction time is 2-4 seconds, and secondary reactions beneficial to the product quality are inhibited. Because the flow of oil and gas and catalyst in the riser reactor is close to plug flow, it is necessary to ensure that the catalyst entering the riser reactor is continuously transported.

Disclosure of Invention

The invention aims to provide a method and a system for preparing low-carbon olefin from an oxygen-containing compound, and the method can be used for providing a carbon deposition catalyst for the reaction of preparing the low-carbon olefin from the oxygen-containing compound and flexibly adjusting the carbon deposition of the required catalyst.

The invention provides a method for preparing low-carbon olefin by using oxygen-containing compounds, which comprises the following steps: a. feeding the raw material containing the oxygen-containing compound into a reactor to contact with the mixed catalyst from the catalyst tank, and performing dehydration to prepare olefin for reaction to generate oil gas rich in low-carbon olefin and spent catalyst; b. separating oil gas rich in low-carbon olefin from spent catalyst, sending the separated oil gas rich in low-carbon olefin into a product separation and recovery system, leading out spent catalyst from the reactor, conveying the spent catalyst to the catalyst tank, and mixing the spent catalyst with regenerated catalyst from a regenerator to obtain the mixed catalyst; c. conveying part of the mixed catalyst obtained in the step b to the reactor to contact with a raw material containing an oxygen-containing compound and carrying out dehydration to prepare olefin reaction, conveying the other part of the mixed catalyst obtained in the step b to a regenerator and carrying out scorching regeneration in an oxygen-containing atmosphere, and separating to obtain the regenerated catalyst and regenerated flue gas; d. transferring the regenerated catalyst obtained in step c to the catalyst tank.

Preferably, the total carbon content of the mixed catalyst entering the reactor is 4-30 wt%.

Preferably, the method further comprises: c obtained by separating the product through the product separation and recovery system₄ ⁺Hydrocarbons are returned to the reactor to carry out the reaction togetherAnd (5) dehydrating to prepare olefin.

Preferably, the reactor, catalyst tank and/or regenerator are optionally provided with at least one heat removal device.

Preferably, a diluent is fed into the reactor with the feedstock comprising oxygenate; wherein the diluent is at least one selected from the group consisting of water vapor, nitrogen, methane, hydrogen, ethane, propane, butane, carbon monoxide and carbon dioxide, and the molar ratio of the feedstock comprising the oxygenate to the diluent is (12-1): 1.

Preferably, the oxygenate in the feedstock comprising oxygenate is at least one selected from the group consisting of alcohols, ethers and esters.

Preferably, the catalyst is a molecular sieve catalyst, wherein the molecular sieve in the molecular sieve catalyst is a silicoaluminophosphate molecular sieve and/or an aluminosilicate molecular sieve.

Preferably, the reaction conditions for producing olefins by dehydration are as follows: the reaction temperature is 200-700 ℃, and the reaction pressure is 0.1-10 MPa.

Preferably, the conditions for coke-burning regeneration are as follows: the regeneration temperature is 450-790 ℃, the regeneration pressure is 0.15-10 MPa, and the oxygen-containing atmosphere is air diluted by air, oxygen, nitrogen, carbon dioxide or oxygen-enriched gas as a fluidizing medium.

Preferably, the method further comprises: injecting quench medium into the reactor from one or more quench medium lines downstream in the reactor; wherein the chilling medium is a refrigerant or a cooled catalyst, and the refrigerant is the raw material containing oxygen-containing compounds and/or water which is not preheated.

The invention also provides a system for preparing low-carbon olefin by using the oxygen-containing compound, which comprises a reactor, a catalyst tank and a regenerator; the reactor is provided with a raw material inlet comprising an oxygen-containing compound, a reactor mixed catalyst inlet, an oil gas outlet rich in low-carbon olefin and a spent catalyst outlet, the catalyst tank is provided with a spent catalyst inlet, a regenerated catalyst inlet, a first mixed catalyst outlet and a second mixed catalyst outlet, and the regenerator is provided with an oxygen-containing gas inlet, a regenerator mixed catalyst inlet, a regenerated catalyst outlet and a regenerated flue gas outlet; the mixed catalyst inlet of the reactor is communicated with the first mixed catalyst outlet of the catalyst tank, the spent catalyst outlet of the reactor is communicated with the spent catalyst inlet of the catalyst tank, the mixed catalyst inlet of the regenerator is communicated with the second mixed catalyst outlet of the catalyst tank, and the regenerated catalyst outlet of the regenerator is communicated with the regenerated catalyst inlet of the catalyst tank.

Preferably, the reactor is at least one selected from the group consisting of a dense bed type reactor, a fast bed type reactor, and a riser type reactor.

Preferably, the riser-type reactor is an equal-diameter riser reactor, an equal-linear-speed riser reactor, a reducing riser reactor or a riser encrypted phase reactor.

Preferably, the system includes a chilled media line in fluid communication with the reactor through one or more chilled media inlets disposed downstream in the reactor.

Preferably, the reactor is provided with a reactor filter and/or a cyclone separator for separating oil gas rich in low-carbon olefin and spent catalyst, and the regenerator is provided with a regenerator filter and/or a cyclone separator for separating regenerated flue gas and regenerated catalyst; wherein the reactor filter and the regenerator filter are each independently a metal sintered porous material and/or a ceramic porous material, the reactor filter has a 2 μm particle filtration accuracy of 99.9%, and the regenerator filter has a 10 μm particle filtration accuracy of 99.9%.

Compared with the prior art, the method and the system for preparing the low-carbon olefin by the oxygen-containing compound have the following main advantages:

1. the spent catalyst and the regenerated catalyst can be mixed and used for reaction through a catalyst circulating device, namely a catalyst tank, between the reactor and the regenerator, the catalyst is continuously conveyed for the reactor, and the continuous operation of the reactor is maintained;

2. more importantly, through the use of the catalyst tank, the hydrocarbon atmosphere of the reactor can be well isolated from the oxygen-containing atmosphere of the coke burning regeneration of the regenerator, so that the safe operation of the process can be ensured;

3. furthermore, the fixed carbon and the temperature of the mixed catalyst can be flexibly adjusted by using the catalyst tank, so that the fixed carbon and the temperature of the mixed catalyst are favorable for the reaction of preparing olefin by dehydration;

4. the reactor adopts the reactor filter to separate the catalyst and the gas product, effectively filters catalyst dust carried in the gas product, and overcomes the problem of natural loss of the catalyst generated by separating the catalyst and the reaction product by adopting a cyclone separator;

5. the regenerator adopts a regenerator filter to separate the catalyst from the regenerated flue gas, effectively filters catalyst dust carried by the regenerated flue gas, and can effectively control the content of catalyst fine powder.

Additional features and advantages of the invention will be set forth in the detailed description which follows.

Drawings

The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the principles of the invention and not to limit the invention. In the drawings:

FIG. 1 comprises a schematic flow diagram of a first embodiment of the method of the present invention, and also comprises a schematic structural diagram of a first embodiment of the system of the present invention;

FIG. 2 comprises a schematic flow diagram of a second embodiment of the method of the present invention, and also comprises a schematic structural diagram of a second embodiment of the system of the present invention;

FIG. 3 comprises a schematic flow diagram of a third embodiment of the method of the present invention, and also comprises a schematic structural diagram of a third embodiment of the system of the present invention;

the invention may also include other embodiments and is not limited to the above.

Description of the reference numerals

1 dense-phase bed reactor 2 fluidized bed regenerator 3 feed line 4 feed distributor

5-heat-taking device 6-dust-falling cap 7-cyclone separator 8-reaction product line

9 main wind 10 heat collector 11 cyclone separator

12 flue gas line 13 line 14 line

15 line 16 line 17 catalyst tank 18 stripping medium line 19 stripping gas line

101 riser reactor 102 expanded diameter riser 103 dense bed reactor

104 settling zone 105 regenerator 106 pre-lift line 107 feed line

108 reactor filter 109 reaction product line 110 heat extractor

111 heat collector 112 main air 113 heat collector

114 regenerator filter 115 flue gas line 116 catalyst pot 117 line

Line 118 line 119 line 120 line 121 stripping medium line 122 stripping gas line

Detailed Description

The following detailed description of embodiments of the invention refers to the accompanying drawings. It should be understood that the detailed description and specific examples, while indicating the present invention, are given by way of illustration and explanation only, not limitation.

Research shows that the contact of the oxygen-containing compound and the catalyst with certain carbon deposition is beneficial to the rapid reaction, because on one hand, the carbon deposition in the catalyst is used as an active center to continuously react with the oxygen-containing compound and introduce alkyl groups; on the other hand, the carbon deposits are also continuously subjected to dealkylation to produce lower olefins such as ethylene and propylene, i.e., so-called "pool" reaction. The catalyst tank is used for mixing the spent catalyst and the regenerated catalyst, and the fixed carbon of the regenerated catalyst is generally less than that of the spent catalyst, and the temperature of the regenerated catalyst is high, so that the mixed catalyst fed into the reactor can contain the fixed carbon, the spent catalyst and the regenerated catalyst can exchange heat, and the reaction temperature is controlled, wherein the temperature of the catalyst tank can be 200-600 ℃, preferably 300-500 ℃, the pressure can be 0.1-10 MPa, preferably 0.2-6 MPa, the catalyst tank can be provided with a stripping device and/or a fluidizing device, and the fluidizing device can be filled with a fluidizing medium to perform the functions of fluidizing, stripping and stirring the catalyst. In addition, on one hand, the catalyst tank may be provided with a catalyst taking port, so that the mixed catalyst can be taken out from the catalyst tank at any time to detect and further control fixed carbon of the mixed catalyst, and on the other hand, a person skilled in the art may also adjust and control fixed carbon of the mixed catalyst according to experience, which is not described in detail herein.

According to the present invention, the total carbon content of the mixed catalyst entering the reactor may be 4 to 30 wt%, preferably 6 to 20 wt%, and more preferably 8 to 15 wt%. The total carbon content of the catalyst is also called catalyst fixed carbon, namely the carbon deposit content on the catalyst, and means the mass percentage of the carbon deposit on the catalyst in the catalyst.

In accordance with the present invention, those skilled in the art will appreciate thatThe oil gas rich in the low-carbon olefin is separated by a product separation and recovery system to obtain a part of C₄ ⁺Hydrocarbons, the C may be used to increase the selectivity of the lower olefins₄ ⁺The hydrocarbons are returned to the reactor to carry out the dehydration to olefin reaction, C₄ ⁺Cracking of hydrocarbons to lower olefins, said C₄ ⁺The hydrocarbon means C₄And C₄The above hydrocarbons.

Since the oxygenate to lower olefins and the regeneration of the spent catalyst are both exothermic reactions, at least one heat removal device may optionally be provided in the reactor, regenerator and/or catalyst tank, as is well known to those skilled in the art. In addition, in order to control the flow of the catalyst, valves may be provided on the lines connecting the reactor, the catalyst tank and the regenerator.

According to the present invention, in order to facilitate the reaction for producing olefins by dehydration in the forward reaction direction, a diluent may be fed into the reactor together with the feedstock comprising an oxygenate; wherein the diluent may be at least one selected from the group consisting of steam, nitrogen, methane, hydrogen, ethane, propane, butane, carbon monoxide and carbon dioxide, and the molar ratio of the feedstock including an oxygenate to the diluent may be (12-1): 1.

According to the present invention, the oxygenate-containing raw material is well known to those skilled in the art, wherein the oxygenate may be at least one selected from alcohols, ethers and esters, preferably at least one selected from methanol, ethanol, methyl ether, ethyl ether, methyl ethyl ether, dimethyl carbonate and methyl formate, more preferably methanol, and may be other industrial or natural oxygenates, without limitation.

According to the invention, the catalyst is well known to the person skilled in the art and may be, for example, a molecular sieve catalyst, the molecular sieve in the molecular sieve catalyst may be a silicoaluminophosphate molecular sieve, which may be a SAPO series and/or SRM series molecular sieve, and/or an aluminosilicate molecular sieve, which may be a ZSM series and/or ZRP series molecular sieve. In addition, the molecular sieve may support at least one element selected from the group consisting of alkaline earth metals, K, Zr, Ti, Co, Mo, Ni, Pt, Pd, La, Ce, Cu, Fe, B, Si, P, Sn, Pb, Ga, Cr, V, Sc, Ge, Mn, La, Al, Ni, and Fe.

The reactions for the production of olefins by dehydration according to the present invention are well known to those skilled in the art and may be carried out under the following conditions: the reaction temperature can be 200-700 ℃, and is preferably 250-600 ℃; the reaction pressure may be 0.1 to 10MPa, preferably 0.15 to 5MPa, and more preferably 1 to 3.5 MPa.

According to the present invention, the conditions for the coke-burning regeneration are well known to those skilled in the art, for example, the regeneration temperature may be 450 to 790 ℃, preferably 500 to 600 ℃, the regeneration pressure may be 0.15 to 10MPa, preferably 0.2 to 5.5MPa, and the oxygen-containing atmosphere may be air, oxygen, air diluted with nitrogen, carbon dioxide or oxygen-rich gas as a fluidizing medium, preferably carbon dioxide and/or oxygen.

Since the production of lower olefins from oxygenates is an exothermic reaction, the reactor may be provided with one or more chilled medium lines to control the reaction temperature in accordance with the present invention. According to one embodiment of the invention, quench medium may be injected into the reactor from one or more quench medium lines midway downstream (with respect to the feed flow direction) of the reactor; wherein the chilling medium may be a chilling agent or a cooled catalyst, and the chilling agent may be the feedstock including an oxygen-containing compound and/or water without preheating.

In order to separate the oil gas rich in light olefins from the spent catalyst, a conventional cyclone separator can be used, which is well known to those skilled in the art, and the present invention will not be described in detail.

The separation of the regenerated flue gas from the regenerated catalyst may be performed by conventional cyclones, which are well known to those skilled in the art and will not be described in detail herein.

According to a preferred embodiment of the present invention, the hydrocarbon rich in light olefins and the spent catalyst can be separated by a reactor filter, wherein the reactor filter can be made of a porous material, for example, a metal sintered porous material and/or a ceramic porous material; the 2 μm particle filtration precision of the reactor filter can reach 99.9%, and preferably, the 1.2 μm particle filtration precision of the reactor filter can reach 99.9%; in addition, back-blowing gas can be used for back-blowing the reactor filter to clean filter cakes; the blowback gas may be at least one selected from hydrocarbon-containing gas, dry gas, nitrogen and water vapor.

According to a preferred embodiment of the present invention, the regenerated flue gas and the regenerated catalyst can be separated by a regenerator filter, wherein the regenerator filter can be made of a porous material, for example, a metal sintered porous material and/or a ceramic porous material; the 10 μm particle filtration precision of the regenerator filter can reach 99.9%, and preferably, the 8 μm particle filtration precision of the regenerator filter can reach 99.9%; in addition, the filter cake can be cleaned by back-blowing the regenerator filter by back-blowing air; the back-blowing gas can be one or more selected from hydrocarbon-containing gas, dry gas, nitrogen, flue gas, carbon dioxide, carbon monoxide, air and water vapor.

The reactor according to the present invention is well known to those skilled in the art and may be, for example, at least one selected from the group consisting of a dense bed type reactor, a fast bed type reactor and a riser type reactor.

The dense bed type reactor according to the present invention is well known to those skilled in the art and may be, for example, a constant diameter dense bed reactor, a constant linear velocity dense bed reactor, a variable diameter dense bed reactor, or a fast bed dense phase reactor. In addition, the dense-phase bed type reactor can be provided with a feeding stripping section, a distributor, a dense-phase bed, an expanding dense-phase bed, a reducing hole, a dust falling cover, a settling zone and other common industrial devices from bottom to top along the vertical direction, so that the dense-phase bed type reactor can continuously run; the settling zone, the filter and other devices may form the oil agent separation zone, and the oil agent separation zone may also include other devices for separating the spent catalyst from the oil gas, which is not limited in the present invention.

According to the present invention, the fast bed type reactor is well known to those skilled in the art, and may be, for example, a constant diameter fast bed reactor, a constant linear velocity fast bed reactor, a variable diameter fast bed reactor or a riser-riser fast bed reactor. In addition, the fast bed type reactor can be provided with a feeding pre-lifting section, a fast bed, a chilling medium pipeline, an expanding fast bed, a reducing section, a fast separating section, a stripping section, a settling zone, a filter and other common industrial devices from bottom to top along the vertical direction, so that the fast bed type reactor can continuously run; the settling zone, the filter and other devices may form the oil agent separation zone, and the oil agent separation zone may also include other devices for separating the spent catalyst from the oil gas, which is not limited in the present invention.

According to the present invention, the riser-type reactor is well known to those skilled in the art, and may be, for example, a constant diameter riser reactor, a constant linear velocity riser reactor, a variable diameter riser reactor, or a riser-packed phase reactor. In addition, the riser-type reactor can be provided with a pre-lifting section, a lifting pipe, a chilling medium pipeline, an expanding lifting pipe, a reducing diameter, a quick separation section, a stripping section, a dense-phase section, a settling zone, a filter and other common industrial devices from bottom to top along the vertical direction, so that the riser-type reactor can continuously run; the settling zone, the filter and other devices may form the oil agent separation zone, and the oil agent separation zone may also include other devices for separating the spent catalyst from the oil gas, which is not limited in the present invention. According to the invention, the dense bed of the riser-type reactor may not form a dense bed, i.e. a "zero level".

Since oxygenate to lower olefins is an exothermic reaction, according to the present invention, the system may include a quench medium line that may be in fluid communication with the reactor via one or more quench medium inlets disposed downstream in the reactor to introduce quench medium into the reactor.

According to the invention, the reactor can be provided with a reactor filter and/or a cyclone separator for separating oil gas rich in low-carbon olefin from a spent catalyst, and the regenerator can be provided with a regenerator filter and/or a cyclone separator for separating regenerated flue gas from a regenerated catalyst; wherein the reactor filter and the regenerator filter may each independently be a metal sintered porous material and/or a ceramic porous material, the reactor filter may have a 2 μm particle filtration precision of 99.9%, and preferably, the reactor filter may have a 1.2 μm particle filtration precision of 99.9%; the 10 μm particulate filtration accuracy of the regenerator filter may be 99.9%, and preferably, the 8 μm particulate filtration accuracy of the regenerator filter may be 99.9%.

The following further describes embodiments of the present invention with reference to the drawings, but the present invention is not limited thereto.

First embodiment

As shown in fig. 1, a raw material containing an oxygen-containing compound is contacted with a mixed catalyst from a catalyst tank in a reactor to perform a dehydration reaction to prepare olefins, and the obtained spent catalyst enters the catalyst tank to be mixed with a regenerated catalyst from a regenerator to obtain the mixed catalyst. And feeding part of the mixed catalyst into a reactor for reaction, feeding the other part of the mixed catalyst into a regenerator for regeneration, and feeding the obtained regenerated catalyst into a catalyst tank to be mixed with the catalyst to be regenerated.

Second embodiment

As shown in fig. 2, a raw material containing an oxygen-containing compound enters a dense bed type reactor 1 from a feed line 3 through a feed distributor 4, contacts with a mixed catalyst conveyed from a catalyst tank 17 through a line 13 to perform a reaction for producing olefins by dehydration, an internal heat collector 5 takes out excess heat of the dense bed reactor 1, the generated oil gas rich in low carbon olefins and spent catalyst enter a settling zone through a dust fall cap 6, the oil gas rich in low carbon olefins and the carried spent catalyst fine powder are separated by a cyclone separator 7, the oil gas rich in low carbon olefins is conveyed to a product separation and recovery system (not shown) through a line 8, the separated spent catalyst returns to the dense bed reactor 1, and part of the spent catalyst deposited with carbon is stripped and conveyed to the catalyst tank 17 through a line 14.

The mixed catalyst from the catalyst tank 17 is sent into the fluidized bed regenerator 2 through a pipeline 16 to be in countercurrent contact with the main air from a pipeline 9 for low-temperature scorching regeneration, the redundant heat is taken out through the internal heat collector 10, the flue gas and the regenerated catalyst are separated through the cyclone separator 11, the flue gas is sent into a subsequent energy recovery and purification system (not shown) through a pipeline 12, and the regenerated catalyst is sent into the catalyst tank 17 through a pipeline 15.

Spent catalyst from reactor 1 and regenerated catalyst from regenerator 2 are mixed in catalyst tank 17, stirred, fluidized and stripped by stripping medium from line 18 to obtain mixed catalyst, and the stripped gas is discharged from catalyst tank 17 through line 19.

Third embodiment

As shown in fig. 3, the mixed catalyst from the pipeline 118 is pre-lifted and lifted by the pre-lift line 106, and then fed into the riser reactor 101 of the riser reactor, the raw material containing oxygen-containing compound and diluent enter the riser reactor 101 through the feed line 107, contact with the mixed catalyst and undergo dehydration to produce olefin reaction, the oil gas continues to react in the expanded diameter riser 102 after reaction, the excess heat released by the reaction is taken away by the heat remover 110 and the reaction temperature is controlled, the reaction oil gas and catalyst enter the dense phase reactor 103, the unconverted raw material continues to contact and react with the catalyst in the dense phase reactor 103, the excess reaction heat is taken out by the heat remover 111, the oil gas rich in low carbon olefin and spent catalyst enter the settling zone 104 for settling, the spent catalyst enters the dense phase reactor 103, the oil gas rich in low carbon olefin and the fine powder of the spent catalyst carried by the reactor filter 108, the oil gas rich in the low carbon olefin is sent to a product separation and recovery system (not shown) through a pipeline 109, and the filtered spent catalyst fine powder is settled and returned to the dense-phase bed reactor 103. After the spent catalyst is stripped in the stripping section, a portion of the stripped spent catalyst is sent to the catalyst tank 116 via line 117.

The mixed catalyst from the catalyst tank 116 is sent to the fluidized bed regenerator 105 through a pipeline 120 to be contacted with the main air from the pipeline 112 for low-temperature coke burning regeneration, the surplus heat is taken out through the internal heat collector 113, the flue gas and the regenerated catalyst are separated through the regenerator filter 114, the flue gas is sent to a subsequent energy recovery and purification system (not shown) through a pipeline 115, and the regenerated catalyst is sent to the catalyst tank 116 through a pipeline 119.

Spent catalyst from reactor 101 and regenerated catalyst from regenerator 105 are mixed in catalyst tank 116, and the mixed catalyst is obtained after agitation, fluidization and stripping by the stripping medium from line 121, and the stripped gas is discharged from catalyst tank 116 via line 122.

The invention will be further illustrated by the following examples, but is not to be construed as being limited thereto.

In the embodiment of the invention, the gas product is measured by adopting gas chromatography, the liquid product is measured by adopting liquid chromatography, and the selectivity of the hydrocarbon product is calculated, wherein C is₅-C₁₂The hydrocarbons of (a) are attributed to gasoline.

The selectivity calculation described in the examples of the invention is the same process for the preparation of hydrocarbons from oxygenates (ethylene is taken as an example):

ethylene selectivity-ethylene yield/non-aqueous product yield;

non-aqueous products include: h2, methane, C2, and hydrocarbons above C2 (including coke, excluding oxygenates).

The preparation of catalyst C used in examples 1 and 2 is as follows:

1417 g of phosphoric acid (85% phosphoric acid, chemical purity reagent, the same below) and 5530 g of deionized water were added to a gel-forming kettle placed in a water bath at 45 ℃ and mixed well, and 1165 g of hydrated alumina (containing 72% Al) was added thereto after stirring for 30 minutes₂O₃Produced by chang ling division of the catalyst for petrochemical in China, the same applies hereinafter), and stirred and mixed for 2 hours. 730 g of diethylamine (chemical purity reagent, the same below) and 810 g of di-n-propylamine (chemical purity reagent, the same below) were then added to the above-mentioned pot, and after further stirring and mixing for 1 hour, 1538 g of silica sol (containing 26% SiO) was added₂Beijing Changhong chemical plant, the same below), stirring well, adding 80 g AFO structure aluminum phosphate molecular sieve (synthesized according to the method of example 1 of Chinese patent CN 1541942A), stirring well for 2 hours, and preparing reaction mixture. The reaction mixture is sealed into a stainless steel crystallization kettle and stirred for crystallization for 40 hours at 190 ℃ under autogenous pressure. And then filtering and washing the crystallized product, and drying at 100-110 ℃ to obtain a molecular sieve raw powder product A.

1165 grams of hydrated alumina and 3500 grams of deionized water were added to a gel forming kettle placed in a 65 ℃ water bath and mixed for 30 minutes with stirring, and then a solution of 1417 grams of phosphoric acid and 2180 grams of deionized water was added and mixed with stirring for 2 hours. Then 385 g of silica sol is added, stirring is carried out for 0.5 hour, a mixture of 900 g of diethylamine and 812 g of di-n-propylamine is added into the gelling kettle, stirring and mixing are carried out for 1 hour, 60 g of the synthesized molecular sieve raw powder product A is added after uniform stirring, and full stirring is carried out for 2 hours, thus obtaining a reaction mixture. The reaction mixture is packed in a stainless steel crystallization kettle and stirred for crystallization for 48 hours at 190 ℃ under autogenous pressure. And then filtering, washing and drying the crystallized product at 100-110 ℃ to obtain a molecular sieve raw powder product B which is pure-phase SRM-4.

Roasting the SRM-4 molecular sieve raw powder product B (dry basis is 1.35Kg), pulping with decationized water to obtain 4.5Kg of pulp, pulping 1.25Kg of kaolin and 2.79Kg of silica sol with 1.46Kg of decationized water, adding the molecular sieve pulp, stirring uniformly, spray drying and forming, heating the obtained microspheres in a muffle furnace to 550 ℃, and roasting at constant temperature for 1h to obtain the catalyst C. In the catalyst C, the SRM-4 molecular sieve accounts for 45 wt%, the kaolin accounts for 35 wt% and the silica sol accounts for 20 wt% of the total weight of the catalyst C.

Examples 1 to 2

Examples 1-2 the procedure shown in FIG. 2 was followed, C being isolated as a reaction product in example 1₄ ⁺Returning to the reactor to continue the reaction, and the specific reaction and regeneration conditions and the reaction results are shown in Table 1.

Example 3

Example 3 was carried out according to the procedure shown in FIG. 3, and the specific reaction and regeneration conditions and reaction results are shown in Table 1.

Comparative examples 1 to 2

Comparative examples 1-2 were conducted using conventional techniques, the reaction catalyst was a fully coked regenerated catalyst, and the specific reaction and regeneration conditions and reaction results are shown in tables 1 and 2, respectively.

As can be seen from Table 1, with the process of the present invention, due to the high carbon content of the mixed catalyst used for the reaction, the selectivity of ethylene and propylene can be higher than the level of the existing industrial process; it can be seen from table 2 that with the process of the present invention, due to the high carbon content of the mixed catalyst used for the reaction, the propylene and gasoline selectivities are 65.6% and 25.6%, respectively, which are higher or comparable to the state of the art. And because the reaction system of the present invention can be at higher pressures than existing industrial plants, the feedstock throughput of the reaction system of the present invention is higher than existing industrial plants, all other operating conditions being the same.

Table 1 shows the specific reaction and regeneration conditions and the reaction results of examples 1 to 2 of the present invention and comparative example 1

Table 2 shows the specific reaction and regeneration conditions and the reaction results of example 3 and comparative example 2 of the present invention

Claims

1. A process for producing lower olefins from oxygenates, the process comprising:

a. feeding the raw material containing the oxygen-containing compound into a reactor to contact with the mixed catalyst from the catalyst tank, and performing dehydration to prepare olefin for reaction to generate oil gas rich in low-carbon olefin and spent catalyst;

b. separating oil gas rich in low-carbon olefin from spent catalyst, sending the separated oil gas rich in low-carbon olefin into a product separation and recovery system, leading out spent catalyst from the reactor, conveying the spent catalyst to the catalyst tank, and mixing the spent catalyst with regenerated catalyst from a regenerator to obtain the mixed catalyst;

c. conveying part of the mixed catalyst obtained in the step b to the reactor to contact with a raw material containing an oxygen-containing compound and carrying out dehydration to prepare olefin reaction, conveying the other part of the mixed catalyst obtained in the step b to a regenerator and carrying out scorching regeneration in an oxygen-containing atmosphere, and separating to obtain the regenerated catalyst and regenerated flue gas;

d. transferring the regenerated catalyst obtained in step c to the catalyst tank.

2. The process of claim 1, wherein the total carbon content of the mixed catalyst entering the reactor is 4 to 30 wt.%.

3. The method of claim 1, further comprising: c obtained by separating the product through the product separation and recovery system₄ ⁺The hydrocarbons are returned to the reactor to carry out the dehydration to olefin reaction.

4. The process according to claim 1, wherein the reactor, catalyst tank and/or regenerator are optionally provided with at least one heat extraction device.

5. The process of claim 1, wherein a diluent is fed into the reactor with the feedstock comprising oxygenate; wherein the diluent is at least one selected from the group consisting of water vapor, nitrogen, methane, hydrogen, ethane, propane, butane, carbon monoxide and carbon dioxide, and the molar ratio of the feedstock comprising the oxygenate to the diluent is (12-1): 1.

6. The method according to claim 1, wherein the oxygenate in the feedstock comprising oxygenate is at least one selected from the group consisting of alcohols, ethers and esters.

7. The process of claim 1, wherein the catalyst is a molecular sieve catalyst, wherein the molecular sieve in the molecular sieve catalyst is a silicoaluminophosphate molecular sieve and/or an aluminosilicate molecular sieve.

8. The method of claim 1, wherein the conditions of the dehydration to olefins reaction are: the reaction temperature is 200-700 ℃, and the reaction pressure is 0.1-10 MPa.

9. The method of claim 1, wherein the conditions for the char regeneration are: the regeneration temperature is 450-790 ℃, the regeneration pressure is 0.15-10 MPa, and the oxygen-containing atmosphere is air diluted by air, oxygen, nitrogen, carbon dioxide or oxygen-enriched gas as a fluidizing medium.

10. The method of claim 1, further comprising: injecting quench medium into the reactor from one or more quench medium lines downstream in the reactor; wherein the chilling medium is a refrigerant or a cooled catalyst, and the refrigerant is the raw material containing oxygen-containing compounds and/or water which is not preheated.

11. A system for preparing low-carbon olefin by oxygen-containing compound comprises a reactor, a catalyst tank and a regenerator;

the reactor is provided with a raw material inlet comprising an oxygen-containing compound, a reactor mixed catalyst inlet, an oil gas outlet rich in low-carbon olefin and a spent catalyst outlet, the catalyst tank is provided with a spent catalyst inlet, a regenerated catalyst inlet, a first mixed catalyst outlet and a second mixed catalyst outlet, and the regenerator is provided with an oxygen-containing gas inlet, a regenerator mixed catalyst inlet, a regenerated catalyst outlet and a regenerated flue gas outlet;

the mixed catalyst inlet of the reactor is communicated with the first mixed catalyst outlet of the catalyst tank, the spent catalyst outlet of the reactor is communicated with the spent catalyst inlet of the catalyst tank, the mixed catalyst inlet of the regenerator is communicated with the second mixed catalyst outlet of the catalyst tank, and the regenerated catalyst outlet of the regenerator is communicated with the regenerated catalyst inlet of the catalyst tank.

12. The system of claim 11, wherein the reactor is at least one selected from the group consisting of a dense bed type reactor, a fast bed type reactor, and a riser type reactor.

13. The system of claim 12, wherein the riser-type reactor is a constant diameter riser reactor, a constant linear velocity riser reactor, a variable diameter riser reactor, or a riser densified phase reactor.

14. A system in accordance with claim 11 wherein said system comprises a chilled media line in fluid communication with said reactor through one or more chilled media inlets disposed downstream in said reactor.

15. The system of claim 11, wherein the reactor is provided with a reactor filter and/or cyclone for separating the low-carbon olefin-rich oil gas and the spent catalyst, and the regenerator is provided with a regenerator filter and/or cyclone for separating the regenerated flue gas and the regenerated catalyst; wherein the reactor filter and the regenerator filter are each independently a metal sintered porous material and/or a ceramic porous material, the reactor filter has a 2 μm particle filtration accuracy of 99.9%, and the regenerator filter has a 10 μm particle filtration accuracy of 99.9%.