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Preparation method and use method of modified ZSM-5 molecular sieve based catalyst

A ZSM-5, molecular sieve technology, used in molecular sieve catalysts, including molecular sieve catalysts, catalysts, etc., can solve the problems of catalyst deactivation by carbon deposition, life reduction and other problems, achieve strong aromatization performance, improve acidity, and good resistance. Effect

Inactive Publication Date: 2016-12-14
TSINGHUA UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

It has long been found that reducing the silicon-aluminum ratio is beneficial to improve the selectivity of aromatization. For a long time, a lower silicon-aluminum ratio has been pursued to achieve high aromatics selectivity, but it brings a strong coking ability, making the catalyst It is very easy to deactivate by carbon deposition, and the lifespan decreases rapidly with the decrease of the silicon-aluminum ratio

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0028] Embodiment 1: the preparation method of modified ZSM-5 molecular sieve catalyst comprises the following steps:

[0029] Step 1: Mix and stir 1g ZSM-5 molecular sieve, 0.001g tetrapropylammonium hydroxide (25% aqueous solution), and 0.01g urea at room temperature to form a precursor aqueous solution, then transfer the precursor aqueous solution into a synthesis kettle, Seal and crystallize at 120°C for 72h. After the crystallization is complete, separate the reaction mixture from solid to liquid, wash with deionized water, dry the solid at 90°C for 24h, and finally roast it in an air atmosphere at 450°C for 10h to obtain molecular sieve powder ;

[0030] Step 2: Mix and stir the 1 g of molecular sieve former powder with 10 g of ammonium nitrate solution with a mass fraction of 0.1% for 1 h, filter, and mix and stir the filter cake with 10 g of ammonium carbonate solution with a mass fraction of 20% for 24 h, filter, and repeat this twice, Dry at 90°C for 24h, and calcin...

Embodiment 2

[0033] Embodiment 2: the preparation method of modified molecular sieve catalyst comprises the following steps:

[0034] Step 1: Mix and stir 1g ZSM-5 molecular sieve, 15g tetrapropylammonium hydroxide (25% aqueous solution), 1.8g isopropanol, 20g water, 5g sodium hydroxide, 5g urea, and 4g aluminum nitrate at room temperature to prepare Precursor aqueous solution, then transfer the precursor aqueous solution into the synthesis kettle, seal it, and crystallize it at 200°C for 24h. After the crystallization is complete, separate the reaction mixture from solid to liquid, wash it with deionized water, and dry the solid at 120°C for 3h. Finally, it was calcined in an air atmosphere at 650°C for 1 hour to obtain the raw molecular sieve powder;

[0035] Step 2: Mix 1 g of molecular sieve raw powder with 10 g of ammonium chloride solution with a mass fraction of 0.1% and stir for 24 hours, filter, and mix and stir the filter cake with 10 g of ammonium sulfate solution with a mass fr...

Embodiment 3

[0038] Embodiment 3: the preparation method of modified molecular sieve catalyst comprises the following steps:

[0039] The preparation method of the catalyst is basically the same as in Example 2, except that in step 1, ethylenediamine is used to replace tetrapropylammonium hydroxide, sodium chloride is used to replace isopropanol, sodium carbonate is used to replace sodium hydroxide, and biuret is used to replace urea , aluminum carbonate instead of aluminum nitrate; step 2 with ammonium acetate instead of ammonium nitrate; step 3 with gallium carbonate instead of zinc nitrate.

[0040] The method of using the above-mentioned catalyst is as follows: put the obtained catalyst into a fixed-bed reactor, pass through a mixture of dimethyl ether and methanol with a volume ratio of 1:1, at 475°C, 0.1MPa, and the mass space velocity of the raw material is 0.8h -1 Under the conditions of the reaction, the conversion rate of the raw material methanol is >99%, and the selectivity (ca...

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Abstract

The invention discloses a preparation method and a use method of a modified ZSM-5 molecular sieve based catalyst, and belongs to the technical field of preparation of arene. The preparation method disclosed by the invention comprises the following steps: mixing and stirring a ZSM-5 molecular sieve, an aluminum source, a template agent, a structure auxiliary, an additive, alkaline and water to prepare a precursor aqueous solution, and performing crystallization, solid-liquid separation and roasting to obtain modified molecular sieve raw powder; mixing and stirring the modified molecular sieve raw powder with an ammonium salt solution, filtering, then mixing and stirring with the ammonium salt solution for multiple times, filtering again, and roasting to obtain a hydrogen form ZSM-5 molecular sieve; mixing the hydrogen form ZSM-5 molecular sieve with a metal precursor solution, and performing drying and roasting to obtain an aromatization catalyst. The use method comprises converting an oxygen-containing compound raw material into arene through the catalyst under a reaction condition. The catalyst prepared by the method disclosed by the invention has the characteristic of high arene selectivity.

Description

technical field [0001] The invention belongs to the technical field of preparation of aromatic hydrocarbons, and in particular relates to a method for preparing and using a modified ZSM-5 molecular sieve catalyst. Background technique [0002] Aromatics such as benzene, toluene, p-xylene, trimethylbenzene, and tetramethylbenzene are important chemical raw materials, and their consumption is second only to ethylene and propylene. Among them, trimethylbenzene can prepare various dye intermediates such as trimellitic acid and benzoic anhydride, and can also be used to produce antioxidants, polyester resin curing agents, stabilizers, alkyd resin plasticizers, etc. Mesitylene is a good It is used as a developer for silicone photosensitive sheets in the electronics industry. Pyromellitic dianhydride obtained by oxidation of durene and diamine compounds can be polymerized to produce polyimide engineering plastics. At the same time, p-xylene (PX) can be produced by the disproporti...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): B01J29/40B01J29/46B01J29/48C07C1/20C07C15/04C07C15/24
CPCY02P20/52B01J29/40B01J29/405B01J29/46B01J29/48B01J2229/18C07C1/20C07C2529/40C07C15/04C07C15/24
Inventor 魏飞马云海骞伟中
Owner TSINGHUA UNIV
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