CN1066071C - Preparation of modified macro-porous zeolite catalyst and synthetic isopropyl aromatic hydrocarbon - Google Patents

Abstract

The present invention relates to a preparation method of a modified large-aperture zeolite molecular sieve catalyst. A total of 10 catalysts with different performances of Y-type, β-type, mercerized type, ZSM-5 type and ZSM-12 type have been synthesized, and they are respectively used for benzene or The isopropylation reaction of toluene and propylene produces cumene and cumene. The deactivation, regeneration, long-running and transalkylation properties of the catalyst were also examined. The catalyst not only has the advantages of improving production efficiency, but also has the characteristics of no corrosion, no pollution, high low-temperature reaction activity, small internal diffusion resistance, high selectivity, good activity stability, and good repeatability for multiple regenerations.

Description

Preparation of Modified Large Pore Zeolite Catalyst and Synthesis of Isopropylarenes

The invention relates to the preparation of a modified zeolite catalyst, which is used to catalyze isopropylation of aromatic hydrocarbons to prepare cumene and its derivatives.

Existing industrial production technologies for cumene and cumene mainly include the synthesis method using solid phosphoric acid as a catalyst represented by UOP Company in the U.S. and the trichlorination method adopted by companies such as Sumitomo, Mitsui and U.S. Monsanto/Lummus Crast. Aluminum complexation method. These methods are to adopt benzene or toluene as raw material, carry out electrophilic substitution reaction with isopropylating reagent propylene. The reaction conditions of the solid phosphoric acid method are reaction temperature 190-250°C, pressure 3.0MPa, molar ratio of aromatics/propylene is 6-10; while the reaction temperature of the aluminum chloride complexation method is 100-120°C, pressure 0.1-0.3 MPa, the molar ratio of aromatics/propylene is 3-5. In recent years, the United States G. R． Meima reported using modified mordenite as a catalyst to synthesize cumene at 175°C under normal pressure. The molar ratio of benzene/propylene was 7.7, the weight space velocity was 1.0hr ^-1 , and the selectivity of cumene was 94.7%. (mole), continuous operation for 900 hours, stable activity. Robert A． Innes uses the Hβ zeolite catalyst to carry out alkylation of benzene and propylene to synthesize cumene and carry out alkylation to the by-product dicumene. The reaction temperature is 160°C, the pressure is 600Psig, the molar ratio of benzene/propylene is 7.43, and the weight The space velocity is 4.6hr ^-1 , through 500 hours of continuous operation, the conversion rate of propylene is 100%, the selectivity of cumene is 93.1%, the product purity is high, and the (weight)% of product distribution is: cumene 93.1, p-di Cumene 2.7, m-dicumene 4.1, others 0.1. The catalyst also has strong transalkylation ability. American Mobil, Oil. Co． It is reported that the use of HZSM-12 catalyst for the alkylation of toluene and propylene to produce cumene, at a reaction temperature of 260°C, a pressure of 500Psig, a molar ratio of toluene/propylene of 6.25, a weight space velocity of toluene of 5.7hr ^-1 , and propylene Under the condition that the weight space velocity is 0.4hr ^-1 , in the isopropyltoluene obtained, o: between: right=5.3:63.7:31.0, due to its high reaction temperature, the o-isopropyl group in the generated isopropyltoluene High toluene content. Because o-isopropyltoluene is not only difficult to oxidize itself, but also inhibits the oxidation of m- and p-isopropyltoluene, therefore, lowering the reaction temperature is conducive to reducing the content of o-isopropyltoluene, thereby increasing the isopropyl toluene. The reaction rate of methyl toluene in the oxidation process. It can be seen from the table below that the content of o-cymene can be reduced only by lowering the reaction temperature, but when the reaction temperature is too low, it is not conducive to the thermodynamic equilibrium of the reaction product, and the activity of the catalyst must be increased.

Equilibrium composition of cumene at different temperatures Table 1 Reaction temperature (°C) p-cymene (%) m-isopropyltoluene (%) o-isopropyltoluene (%) 100190210250310 30.0830.4530.5430.4330.29 68.5966.9966.5866.0365.05 1.302.562.893.554.66

The use of solid phosphoric acid catalyst or aluminum trichloride complex catalyst for the isopropylation of aromatic hydrocarbons has problems such as serious equipment corrosion, long process flow, troublesome after-treatment of reaction materials, and environmental pollution. Especially the catalytic activity of solid phosphoric acid is low. In the process of synthesizing isopropyl toluene from toluene and propylene, the content of o-isopropyl toluene is as high as 40%. Structured, o-isopropyltoluene content is reduced to about 3%, just can enter next step reaction.

The purpose of the present invention is aimed at the above-mentioned shortcoming that solid phosphoric acid method and aluminum chloride complexation method exist, carry out the isopropylation reaction of arene by adopting large aperture molecular sieve catalyst to prepare isopropyl aromatic hydrocarbon, thereby overcome the reaction temperature bias of molecular sieve catalyst in the past High, resulting in low selectivity, high energy consumption and other problems.

The modification process of large-pore zeolite molecular sieve catalyst mainly adopts the following process to prepare it, which has the characteristics of high low-temperature reaction activity, small internal diffusion resistance, high selectivity, good activity stability, and good repeatability after multiple regenerations.

(1) Preparation of molecular sieve catalyst:

Mix and grind the molecular sieve (including Y-type, β-type, mercerized, ZSM-12) raw powder obtained by hydrothermal synthesis with α-Al ₂ O ₃ ·H ₂ O or Al(OH) ₃ dry glue, and the ratio Molecular sieve: Al ₂ O ₃ =90-50:10-50 (based on dry basis), that is, the content of Al ₂ O ₃ added is 10-50% by weight, and the suitable range is 15-35%. Blend, knead, and extrude with 3-10% nitric acid aqueous solution (can be cylindrical or clover-shaped), the specification is Φ1-4mm, the length is 2-10mm, and the extruded catalyst is dried at 120°C for 2-4 hours , and baked at 540°C for 6 hours before use.

(2) Exchange and modification treatment:

The treatment reagent is a NH ₃ -HNO ₃ -H ₂ O mixed system. In the early stage, Na ⁺ ions in the molecular sieve are mainly exchanged, and an aqueous solution containing NH ₄ ⁺ ions with a concentration of 0.4-0.6N is used. Place the molecular sieve in an aqueous solution of ammonia and nitric acid at a temperature ranging from room temperature to 100°C for ion exchange for 1 to 4 hours. After the exchange is completed, discard the exchange liquid, wash with deionized water, dry at 120°C, and then roast at 540°C , such as repeating twice. In the post-treatment process mainly focusing on pore expansion, an aqueous solution containing H ⁺ -NH ₄ ⁺ -H ₂ O ions is used for treatment, and the temperature is from room temperature to 200°C. A modified molecular sieve catalyst with high catalytic activity and high selectivity is prepared. Due to the modification treatment, the internal pores of the catalyst are enlarged and the internal diffusion resistance of the catalyst is improved.

(3) Ion treatment of modified molecular sieves:

In order to further improve the thermal stability of the catalyst and facilitate repeated regeneration, mixed rare earth (aqueous nitric acid solution containing mainly La ³⁺ and Ce ³⁺ ions) and alkaline earth metal (Mg, Ca) plasma treatment was used.

The treatment temperature is from room temperature to 170° C., evaporated to dryness at 110 to 140° C., and calcined at 500 to 600° C. After being treated by this method, the weight of the catalyst increases by 0.05 to 1.5 percent by weight.

The modified Y-type molecular sieve prepared by the above method is used for the catalytic reaction of toluene-propylene alkylation, the temperature is 140 ° C, the pressure is 0.5 MPa (gauge pressure), the toluene weight space velocity is 1.06, and the mol ratio of toluene/propylene is 8.9, the ratio of the three isomers of cumene in the product is right: between: adjacent=30.2: 66.4: 3.4, the alkylation selectivity is 99.5%, and there is no obvious activity stability in 390 hours of continuous operation Variety.

The catalyst prepared above was subjected to rapid deactivation and regeneration tests for 11 times, and the catalyst activity, selectivity and activity stability had no obvious changes. The conditions for rapid deactivation are as follows: a large weight space velocity of 10-20hr ^-1 , a low toluene/propylene molar ratio of 3-5, a high temperature of 250-290°C, and after 6-10 hours of continuous operation, the catalyst is taken out from the reactor. Purged with N ₂ gas, placed in a muffle furnace and roasted under a temperature program in the presence of oxygen, the initial temperature is 250°C, the end temperature is 500-560°C, and the oxygen concentration is 0.3-21%.

The β-type molecular sieve catalyst treated by the method (1)(2)(3) above, at 140°C, pressure 3.5MPa (gauge pressure), weight space velocity 1.23hr ^-1 , benzene/propylene molar ratio 6.27, catalyst loading 20 grams, after 1008 hours of continuous operation, the catalyst activity is stable, the conversion rate of propylene is not less than 99%, and the isopropylation selectivity is 100%, which is the most outstanding achievement of the present invention.

The β-type molecular sieve catalyst treated with the above (1)(2)(3) method is used for the transalkylation reaction of dicumene and benzene. At a reaction temperature of 200-220°C, mix dicumyl:benzene=1: Under the condition of 5-10 (molar ratio), the operating pressure is 3.0 MPa, the material weight space velocity is 1.06, and after 1000 hours of continuous operation, the diisopropylbenzene alkyl transfer rate is ≥ 85%, and the selectivity is ≥ 97%.

After high space velocity WHSV 5～10hr ^-1 , low benzene/propylene molar ratio of 2～3, quick deactivation and catalyst removal from the reactor, temperature programming in muffle furnace, in the presence of oxygen (0.3～21%), regeneration After 20 times, the catalyst activity has no obvious change, and the activity stability is good.

The results of the preparation of the above catalysts and their application to isopropylation of benzene or toluene show that the modified large-pore diameter zeolite molecular sieve catalyst can not only improve production efficiency, but also has the characteristics of no corrosion, no pollution, high low-temperature reactivity, and internal diffusion resistance. Small size, high selectivity, good activity stability, good reproducibility and other advantages, it is an ideal new type of alkylation catalyst.

Example 1

Weigh 8g of molecular sieve raw powder (weight after dehydration), take 2.63g of SB powder (commercially available Al ₂ O ₃ ) (2.0g on a dry basis after dehydration), mix and grind, and then mix with 6-10ml of 10% nitric acid aqueous solution , kneaded into a dough, extruded, the diameter of the catalyst rod is Φ1mm, dried at 120°C for 2 to 4 hours, and then roasted at 540°C for 6 hours in a muffle furnace, ion-exchanged with 0.6N NH ₄ ⁺ NO ₃ ^- aqueous solution, 4 ml/g catalyst, exchange in 80°C aqueous solution for 2 hours, discard the exchange liquid, then exchange once with the same volume of NH ₄ NO ₃ aqueous solution, pour off the exchange liquid, wash once with the same volume of deionized water, and place in a 120°C oven Medium drying (no time limit, subject to dryness) and then baked at 540°C for 6 hours in a muffle furnace. The tool prepares 1 ^# , 2 ^# , 3 ^# , 4 ^# , 5 ^# molecular sieve catalysts, namely:

1 ^# - ZSM-5 catalyst, 2 ^# - mercerized catalyst,

3 ^# - ZSM-12 type catalyst, 4 ^# - Y type catalyst, 5 ^# - β type catalyst.

Example 2

The 1 ^# , 2 ^# , 3 ^# , 4 ^# , 5 ^# molecular sieve catalysts and industrial solid phosphoric acid catalysts prepared in Example 1 were used for toluene-propylene alkylation reaction. The evaluation device used a small fixed-bed reactor, and the inner diameter of the reactor was Φ8mm, catalyst loading 1.0g, reaction conditions and reaction results are shown in Table 2:

Different Catalysts Catalyzed Toluene-Propylene Alkylation ^* Table 2

^* The reaction pressure is normal pressure, with _N2 as the carrier gas, and the proportions of various substances are calculated on the basis of moles

Example 3

The 4 ^# catalyst prepared in example 1 is processed, then with 0.6N NH ₄ NO ₃ aqueous solution, exchange twice at 80 ℃, pour off the raffinate, wash with water, dry, roast (same as example 1 treatment method), obtain 6 ^#catalyst . Put 6 ^# catalyst in the reaction kettle, in NH ₃ : HNO ₃ =2: 1, (NH ₃ +HNO ₃ ) concentration is 8% (in aqueous solution), 5ml/g catalyst is treated at 170°C for 24 hours, take out, Washed with water, dried, and calcined at 540°C for 6 hours to obtain 7 ^# catalyst.

Example 4

Through the 5 ^# catalyst that example 1 is processed, at room temperature, with 0.4N HNO _Aqueous solution handles 2 hours (5ml/gram catalyst), washing, drying, in 540 ℃ of calcining 6 hours, obtain 8 ^# catalyst.

Example 5

Use catalysts 6 ^# and 7 ^# to carry out the toluene-propylene alkylation reaction, the pressure should be 5kg/cm ² (gauge pressure), and the toluene weight space velocity should be 1.08hr ^-1 .

Load 4.0g of catalyst in the Φ10mm reactor, N ₂ : C ₃ ^- = 2.9: 1 (molar ratio), continuous operation, the reaction results are shown in Table 3:

Continuous operation to investigate the alkylation reaction of toluene-propylene Table 3

Example 6

Catalyzed alkylation of benzene-propylene with 7 ^# and 8 ^# catalysts, the reaction conditions are 70°C, benzene weight space velocity 5.28hr ^-1 , benzene/propylene = 5.6 (molar ratio), normal pressure, in Φ8mm reactor Inner catalyst charge 1.0 gram, reaction result is as table four:

Benzene-Propylene Catalyzed Alkylation Table 4 catalyst Benzene conversion % Cumene Selectivity % Product composition % (mole) Non-Fang benzene C _7～8 Cumene dicumyl 7 ⁼ 8 ⁼ 10.4417.41 88.8492.57 0.340.45 89.1982.31 0.060.03 9.2516.00 1.161.32

Example 7

Use 1.0 g of commercially available mixed rare earths (including La, Ce, etc.), dissolve in 10 ml of 0.4N HNO ₃ , filter, and set aside. Weigh 1.0g of 7 ^# and 8 ^# catalysts, immerse in a certain amount of mixed rare earth nitric acid solution, evaporate to dryness at 120°C, and roast for 6 hours (540°C). At this time, the weight of the catalyst increased by 0.3%, and 10 ^# was obtained catalyst.

Example 8

The benzene-propylene rapid deactivation experiment was carried out with 10 ^# catalyst, the rapid deactivation conditions were 140°C, benzene/propylene = 2, the weight space velocity was 10hr ^-1 , the pressure was 5kg/cm ² , and the benzene conversion rate dropped to the initial level after 8-10 hours. 50% of the activity, stop the reaction, pour out the catalyst from the reactor, and regenerate it in a muffle furnace. The regeneration method adopts a temperature-programmed temperature rise to 540 ° C, and keeps it warm for 6 hours. After the above steps 4 times, the catalyst is subjected to benzene-propylene Alkylation reaction, the reaction result is consistent with the fresh catalyst, the catalyst activity and selectivity have no change, and the activity stability is stable through continuous operation.

Example 9

Using 10 ^# catalyst at 140°C, pressure 3.5MPa, benzene/propylene=6.3, material weight space velocity 1.13hr ^-1 , catalyst loading 20g, reaction tube inner diameter Φ14mm, material flow from bottom to top, the results are shown in the table five:

Investigation on Continuous Operation of Benzene-Propylene Alkylation Table 5 Cumulative time (hours) Liquid phase product composition % (mole) Catalytic performance Non-Fang benzene C _7～8 Cumene m-Dicumyl p-dicumene o-dicumene >C ₁ : Aromatics C _B % S _C % 482644087921008 / 85.8385.4685.0485.6186.35 / 13.3013.5013.8913.4013.47 0.550.570.570.480.56 0.320.470.500.510.61 // // 14.2014.5414.9614.3914.65 93.8692.7892.8593.1292.87

Example 1O

The investigation on the transalkylation of dicumylbenzene and benzene on catalyst 10 ^# at 200°C is shown in Table 6:

Investigation of liquid-phase transalkylation between dicumylbenzene and benzene Table 6 Cumulative time (hours) Material composition % (mol) Cumene/∑Diiso Non-Fang benzene C _7～8 Cumene n-Propylbenzene Inter-Different pair-difference Ortho-Different >C ₁ : (reaction material) 203060 0.170.710.410.47 92.5887.0187.7087.75 /0.140.100.09 1.4711.3811.0210.93 /0.060.040.04 3.260.260.250.30 2.150.440.470.42 / / 0.2516.2615.1015.17

Claims (11)

1. a class is used for the preparation method of alkylating zeolite molecular sieve catalyst, it is characterized in that this catalyst is the preparation through zeolite molecular sieve, exchange then and modification, make ion processing or rare earth dipping at last, make modified macroporous footpath zeolite molecular sieve catalyst; The preparation of zeolite molecular sieve be Y type that hydrothermal synthesis method is obtained, β type, mercerising, ZSM-5, ZSM-12 molecular screen primary powder respectively with α-Al ₂O ₃H ₂O or Al (OH) ₃, press molecular sieve: Al ₂O ₃=90～50: 10～50 percentage by weight mixed grindings are even, again with 3～10% aqueous solution of nitric acid blendings, mix pinch, extrusion becomes Φ 1～4mm, long 2～10mm column type or trifolium-shaped catalyst, in 120 ℃ of dryings 2～4 hours, 540 ℃ of roastings formed in 6 hours; Exchange is 0.4～0.6N NH with the reagent that modification is handled ₄ ⁺NO ₃ ^-The aqueous solution ℃ carried out ion-exchange 1～4 hour in room temperature～100, exchange twice, and washing, 120 ℃ of dryings, H is used in 540 ℃ of roastings again ⁺-NH ₄ ⁺-H ₂The O deionized water solution, ℃ reaming is handled in room temperature～200; Ion processing is with containing La ³⁺, Ce ³⁺Ion be main mishmetal aqueous solution of nitric acid and contain Mg, the Ca alkaline-earth metal ions is handled, dipping temperature is room temperature～170 ℃, behind 110～140 ℃ of evaporates to dryness, in 500～600 ℃ of roastings, make make 1 ^#-ZSM-5 type, 2 ^#-mercerising type, 3 ^#-ZSM-12 type, 4 ^#-Y type and 5 ^#-β-type catalyst all can increase weight 0.05～1.50%.

2. according to claim 1 described 1 ^#The purposes of-ZSM-5 type catalyst is characterized in that this catalyst is used for the alkylated reaction of toluene-propylene, under normal pressure, with N ₂Be carrier gas, 250 ℃ of reaction temperatures, the mol ratio of toluene/propylene are 8, and the toluene by weight air speed is 4.1hr ^-1, can make isopropyl toluene.

3. according to the described Preparation of catalysts method of claim 1, it is characterized in that with make 4 ^#-Y type catalyst is used 0.6N NH again ₄NO ₃The aqueous solution, at 80 ℃ of exchange secondaries, washing, dry, roasting can make 6 ^#Catalyst.

4. according to described in the claim 36 ^#The purposes of catalyst is characterized in that carrying out toluene-propylene alkylated reaction with it, and gauge pressure is 5kg/cm ², the toluene by weight air speed is 1.08h ^-1, reaction temperature is 250 ℃, can make isopropyl toluene.

5. according to the method for Preparation of catalysts described in the claim 3, it is characterized in that with make 6 ^#Catalyst is at NH ₃: HNO ₃=2: 1, NH ₃+ HNO ₃Concentration be 8%, handled 24 hours at 170 ℃, washing, dry, 540 ℃ of roastings 6 hours make 7 ^#Catalyst.

6. according to described in the claim 57 ^#The purposes of catalyst is characterized in that carrying out toluene-propylene alkylated reaction with it, and the mol ratio of toluene/propylene is 8.9, and gauge pressure is 0.5MPa, and the weight space velocity of toluene is 1.06hr ^-1, reaction temperature is 140 ℃, can make isopropyl toluene.

7. according to described in the claim 57 ^#The purposes of catalyst is characterized in that this catalyst is carried out the alkylated reaction of benzene-propylene, and the mol ratio of benzene/propylene is 5.6, and under the normal pressure, reaction temperature is 70 ℃, and the benzene weight space velocity is 5.28hr ^-1, can make isopropylbenzene.

8. according to the described Preparation of catalysts method of claim 1, it is characterized in that with make 5 ^#-β type catalyst was at room temperature handled 2 hours with the 0.4N aqueous solution of nitric acid, washing, dry, 540 ℃ of roastings 6 hours, make 8 ^#Catalyst.

9. according to described in the claim 88 ^#The purposes of catalyst is characterized in that carrying out with it the alkylated reaction of benzene-propylene, and the mol ratio of benzene/propylene is 5.6, and under the normal pressure, reaction temperature is 70 ℃, and the benzene weight space velocity is 5.28hr ^-1, can make isopropylbenzene.

10. according to the method for Preparation of catalysts described in the claim 8, it is characterized in that with make 8 ^#Catalyst and the mishmetal that contains La, Ce flood in the 0.4N salpeter solution, and at 120 ℃ of evaporates to dryness, then 540 ℃ of roastings 6 hours, make 10 of weightening finish 0.3% ^#Catalyst.

11. according to described in the claim 10 10 ^#The purposes of catalyst is characterized in that carrying out with it the alkylated reaction of benzene-propylene, and the mol ratio of benzene/propylene is 6.3, and pressure is 3.5MPa, 140 ℃ of reaction temperatures, and the benzene weight space velocity is 1.13hr ^-1, can make isopropylbenzene.