Method for preparing catalyst for compounding p-diethylbenzene by alkylation reaction of ethylbenzene and ethane or alcohol

Abstract

The invention relates to a method for preparing catalyst for compounding p-diethylbenzene by the alkylation reaction of ethylbenzene and ethane or alcohol, and the obtained catalyst can be used for compounding p-diethylbenzene by the alkylation reaction of ethylbenzene and ethane or compounding p-diethylbenzene by the alkylation reaction of the ethylbenzene and alcohol. The catalyst is formed in such a way that an HZSM-5 molecular sieve of SiO2 / Al2O3 molar ratio=16-200 as a matrix to be loaded with silicon dioxide and then roasted and passivated by air and water vapor. The preparation of the catalyst only needs three-step operation; and compared with the prior method for preparing the similar catalyst, the invention greatly simplifies the preparation process. The method does not need to add other substances to further modify the HZSM-5 molecular sieve, thereby having low raw material cost and production energy consumption as well as less environmental pollution and obtaining favorable p-diethylbenzene selectivity and yield.

Description

technical field [0001] The invention relates to a preparation method of a modified HZSM-5 catalyst, which can be used in the alkylation reaction of ethylbenzene and ethylene, or the alkylation reaction of ethylbenzene and ethanol to synthesize p-diethylbenzene. The preparation method has the advantages of simple operation, low cost, less environmental pollution, high single-pass yield of p-diethylbenzene, high selectivity and the like. Background technique [0002] P-diethylbenzene is an essential analytical agent in the process of adsorption and separation of p-xylene, and its synthesis has very important social benefits and practical value. The industry requirement for p-diethylbenzene as a p-xylene desorbent is that its purity is greater than 95%. However, due to the similar boiling points of p-diethylbenzene, o-diethylbenzene and m-diethylbenzene, the rectification method is used to purify p-diethylbenzene products from mixed diethylbenzene (p-diethylbenzene content 30%...

AI Technical Summary

Problems solved by technology

But for HZSM-5 itself, its acid centers are dominated by strong acids, and the strong acid centers are all over the inner and outer surfaces of the catalyst: in addition, its pore size is slightly larger. If it is directly used as a p-diethylbenzene catalyst, a large number of isomers will be produced, making p-diethylbenzene Diethylbenzene has poor selectivity, so it is often necessary to modify its composition and pores

[0004] Chinese patent CN200410020397.7 adopts the alkylation reaction of ethylbenzene and ethanol to synthesize p-diethylbenzene, and SiO 2 / Al 2 o 3 =100 HZSM-5 molecular sieve is used as the matrix, and the surface acidity and pore structure of the molecular sieve are adjusted with components such as boron, magnesium and cobalt. In 10 hours, although the selectivity to diethylbenzene was close to 100%, the initial activity of ethylbenzene was not high, so that the yield of diethylbenzene was only 14%; and the mol ratio of ethylbenzene and ethanol reached 2: 1, so that Ethanol is less efficient

Chinese patent CN90101436.2 adopts the reaction of ethylbenzene and ethanol, and HZSM-5 molecular sieves are respectively modified with aluminum, magnesium and other components and then roasted. The highest conversion rate of ethylbenzene is only 10%, and the selectivity to diethylbenzene between 95% and 98%; the conversion rate of ethylbenzene in U.S. Patent No. 5,811,613 is 8%, and the selectivity of p-diethylbenzene is between 97% and 98%. The reaction yields in the above two patents are all low, which is unfavorable for industrialization

Chinese patent CN200310116628.X uses nanometer HZSM-5 molecular sieve and Al 2 o 3 As the matrix, one or two kinds of active components containing lanthanum, silicon, phosphorus or magnesium are supported respectively to prepare a modified catalyst. 97.02~98.40%, but the preparation of the patented catalyst requires multiple loads, the preparation conditions are difficult to control, and requires multiple roasting, and the preparation energy consumption is high; Chinese patent CN94110202.5 uses silicon mixed rare earth modified HZSM-5 molecular sieve catalyst, B The conversion rate of benzene is 19.20%, but the selectivity to diethylbenzene is only 95.08%

[0005] In previous patents, in order to improve product selectivity, it was often necessary to reduce the strength of the acid center of HZSM-5 and reduce the pore size, such as modifying the strong acid center of HZSM-5 with alkaline earth metal compounds, or using phosphoric acid, boric acid, transition metal compounds, etc. The strong acid center of HZSM-5 is covered with medium strong acid or weak acid substance, or methods such as channel modification and acid strength adjustment are carried out with rare earth compounds. In the process, various active components (or additives) are generally impregnated in molecular sieves step by step. On the parent body, and after each step of impregnation, roasting is required, so the catalyst preparation process has many steps, complex control indicators, high energy consumption, and will cause certain pollution to the environment

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