Shape-selective catalyst preparation method

A technology for catalysts and shape-selective molecular sieves, which is applied in molecular sieve catalysts, chemical instruments and methods, physical/chemical process catalysts, etc., and can solve problems such as expensive modifiers, heterogeneous catalyst performance, and difficulty in achieving diethylbenzene selectivity. , to achieve good activity and stability, long one-way reaction cycle, and high catalyst selectivity

Inactive Publication Date: 2009-06-17
DALIAN UNIV OF TECH
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  • Description
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Problems solved by technology

The disadvantage of this method is: the selectivity to diethylbenzene is difficult to reach more than 98%; the silanization modification step involved needs to use organic solvents such as toluene, xylene, n-hexane or cyclohexane, which is not environmentally friendly
However, the above-mentioned modification method has the following disadvantages: the impregnation modification is carried out at room temperature, which takes a long time; the excess impregnation liquid must be evaporated to dryness at 90 ° C, which consumes time and energy Concentrated continuously, there will be a relatively large difference in loading between the catalyst in contact with the concentrated solution and the catalyst not in contact with the concentrated solution, resulting in inhomogeneous catalyst performance and poor preparation repeatability, which is not conducive to industrial applications; in addition, when using silanization to modify When it is non-toxic, it also involves the environmental problems caused by the use of organic solve

Method used

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Examples

Experimental program
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Effect test

Embodiment 1

[0060] Prepare hydrogen type HZSM-5 molecular sieve catalyst (molecular sieve grain size is 1-2 micron, SiO 2 / Al 2 o 3 =50, extruded, particle size , molecular sieve content 80%, aluminum oxide content 20%), and it is subjected to water vapor passivation (using 100% water vapor, passivation temperature 550 ℃, passivation time 3 hours, water vapor flux is 1 grams (hours) -1 (g catalyst) -1 ). Then carry out hot impregnation with a concentration of 6wt.% lanthanum nitrate solution (calculated as lanthanum oxide) at 80°C, the impregnation time is 2 hours, and a small amount of dilute nitric acid is added dropwise before the impregnating solution is heated to adjust the pH value to between 3-4 , the amount of rare earth nitrate solution is 5ml (gram catalyst) -1 , the times of hot dipping are 1, 2, 3, 4, 5 times respectively. Drying and roasting are carried out after each impregnation. Drying is carried out at 110°C, and the drying time is 3 hours; calcination is carried...

Embodiment 2

[0064] Prepare hydrogen type HZSM-5 molecular sieve catalyst (molecular sieve grain size is 1-2 micron, SiO 2 / Al 2 o 3 =50, extruded, particle size , molecular sieve content 80%, alumina content 20%), and it is subjected to water vapor passivation treatment (using 100% water vapor, passivation temperature 550 ℃, passivation time 3 hours, water vapor flux is 1 grams (hours) -1 (g catalyst) -1 ). Then carry out hot impregnation with a concentration of 6wt.% lanthanum nitrate solution (calculated as lanthanum oxide) at 80°C, the impregnation time is 2 hours, and a small amount of dilute nitric acid is added dropwise before the impregnating solution is heated to adjust the pH value to between 3-4 , the amount of rare earth nitrate solution is 5ml (gram catalyst) -1 , the number of times of hot dipping is 2 times, and drying and roasting are carried out after each dipping. Drying is carried out at 110°C, and the drying time is 3 hours; calcination is carried out at 550°C, ...

Embodiment 3

[0066]Repeat Example 2, but use lanthanum-rich mixed rare earth nitrate (lanthanum oxide / rare earth oxide ≥ 40%) dipping solution instead during hot dipping and cold dipping. Then the total loading capacity of the rare earth oxides of the obtained modified catalyst reaches 15.6wt%. The initial reaction performance of the catalyst in the alkylation reaction of ethylbenzene and ethanol is 21.66% of ethylbenzene conversion rate and 96.64% selectivity to diethylbenzene; 22.77%, 96.32% selectivity to diethylbenzene.

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Abstract

The invention relates to a method for preparing a shape-selective alkylation catalyst, in particular to a method for preparing high-selectivity synthetic p-diethylbenzene catalyst by use of rare earth modification. The method has a main technical characteristic that rare earth modification is completed in two mutually linked steps, namely hot impregnation and cold impregnation. The high-selectivity catalyst prepared by the method has the advantages of high activity, long single-pass reaction period and good regeneration repeatability.

Description

technical field [0001] The invention belongs to the technical field of petrochemical catalysts, and mainly relates to a preparation method of a catalyst used for directly synthesizing high-purity p-diethylbenzene (p-DEB) through ethylbenzene / ethylene (or ethanol) shape-selective alkylation. Background technique [0002] P-diethylbenzene is used as a desorbent for p-xylene in the process of producing p-xylene by adsorption and separation, and the purity of p-diethylbenzene currently sold in the market must reach more than 98%. [0003] There are two ways to obtain p-diethylbenzene, one is to separate it from mixed diethylbenzene by means of adsorption separation. This technology was first invented by UOP Company and industrialized in the mid-1970s. This technology uses metal ion-exchanged zeolite adsorbent, toluene desorbent and simulated moving bed device to produce p-diethylbenzene, which has high energy consumption and equipment investment. Disadvantages such as limited r...

Claims

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Application Information

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IPC IPC(8): B01J29/40C07C15/02C07C2/66
Inventor 郭洪臣王振宇王祥生
Owner DALIAN UNIV OF TECH
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