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Process for combined preparation of p-xylene and low carbon olefin by methylation of toluene

A technology of p-xylene and toluene methylation, applied in the field of toluene methylation to p-xylene co-production of low-carbon olefins, can solve the problems that the catalysts cannot be satisfied at the same time, and the characteristics of the catalysts are different.

Inactive Publication Date: 2006-01-18
DALIAN INST OF CHEM PHYSICS CHINESE ACAD OF SCI
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Problems solved by technology

[0004] The above-mentioned patents respectively propose new ways to prepare p-xylene and low-carbon olefins. Since the two reaction processes are acid-catalyzed reactions, both require shape-selective catalysis, so both use modified HZSM-5 molecular sieves as catalysts. components, but due to the different target products, the characteristics of the catalysts in the two processes are very different, and neither catalyst can meet the requirements of producing p-xylene with high selectivity and producing low-carbon carbon dioxide with high selectivity at the same time. Olefin Process

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0013] ZSM-5 molecular sieve (pore size 0.51×0.55nm, 0.53×0.56nm) (SiO 2 / Al 2 o 3 =61) Roast at 550°C to remove the template agent, exchange 4 times with ammonium nitrate solution in a water bath at 80°C, and roast at 550°C after the exchange to obtain HZSM-5 molecular sieve, then perform selective modification, and then combine with The binder and the pore structure modifier are mixed and molded into a solid catalyst named TMMC-709.

Embodiment 2

[0015] Use the TMMC-709 catalyst prepared in embodiment 1, carry out toluene methanol alkylation reaction on fixed-bed reactor, toluene methanol feeds simultaneously, and reaction condition is: toluene / methanol (molecular ratio)=8 / 1, 4 / 1, 2 / 1, 1 / 1, toluene methanol weight space velocity is 2 hours -1 , N 2 The flow rate was 30ml / min and the temperature was 420°C. Using Varian 3800 gas chromatography, CP-WAX 52CB capillary chromatographic column (25m × 0.25mm) online analysis product distribution (normalized after removing toluene), the results are shown in Table 1.

[0016] When feed toluene / methanol molecular ratio is respectively 8 / 1, 4 / 1, 2 / 1, 1 / 1, the selectivity of p-xylene among xylene isomers in the product is respectively 89.53%, 91.92%, 90.71%, 91.90%, remained basically unchanged; the selectivity of C1-C5 low-carbon hydrocarbons in the product increased, respectively 6.97%, 12.04%, 19.88%, 29.19%; especially the molecular ratio of p-xylene to ethylene in the produ...

Embodiment 3

[0023] Use the TMMC-709 catalyst prepared in Example 1 to carry out the alkylation reaction of toluene methanol on a fixed-bed reactor, toluene methanol is fed simultaneously, and the reaction conditions are: toluene / methanol (mol ratio)=2: 1, toluene methanol Weight airspeed for 2 hours -1 , N 2 The flow rates were 10, 20, 30, 40 ml / min, and the temperature was 420°C. Using Varian 3800 gas chromatography, CP-WAX 52CB capillary chromatographic column (25m × 0.25mm) online analysis product distribution (normalized after removing toluene), the results are shown in Table 2.

[0024] when passing N 2 When the flow rate changes and the contact time is 0.77 seconds, 0.96 seconds, 1.28 seconds, and 1.92 seconds, the selectivity of p-xylene in the product to xylene isomers decreases, which are 93.81%, 90.97%, 85.22%, and 84.24% respectively; C in the product 1 -C 5The selectivity of low-carbon hydrocarbons is respectively 13.40%, 17.76%, 14.89%, 12.30%; the molecular ratio of p-x...

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Abstract

The method of toluene methylating to produce p-xylene and co-product low carbon olefin is that one kind of catalyst is used in producing p-xylene in high selectivity while co-producing ethylene and propylene. During the production, toluene and methylated reagent are fed simultaneously and different operation conditions are adopted so as to reach the selectivity of p-xylene in p-xylene isomers as high as 85-95 %, the selectivity of ethylene and propylene in C1-C5 low carbon hydrocarbons as high as 70-85 %, and the regulation of the molecular ratio between p-xylene and ethylene in the product.

Description

technical field [0001] The invention relates to a method for producing p-xylene through methylation of toluene and co-production of low-carbon olefins, in particular, it relates to a method for producing p-xylene with high selectivity through a reaction process and using a catalyst while producing p-xylene with high selectivity. Co-production of ethylene and propylene. Background technique [0002] P-xylene is an important organic chemical raw material, which is mainly used to synthesize terephthalic acid or dimethyl terephthalate; ethylene is the most important and basic chemical raw material in the chemical industry, and one of its uses is to prepare ethylene glycol Alcohol; Terephthalic acid reacts with ethylene glycol to obtain polyester with excellent properties, which is widely used as raw materials for fibers, films and plastics. At present, p-xylene production mainly uses toluene, C 9 Aromatics and mixed xylenes are used as raw materials, which are produced by disp...

Claims

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Application Information

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IPC IPC(8): C07C15/08C07C11/04C07C11/06C07C2/00C07C1/00
CPCY02P20/52
Inventor 许磊华邦嵩刘中民张新志
Owner DALIAN INST OF CHEM PHYSICS CHINESE ACAD OF SCI
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