S-1 full-silicon molecular sieve and preparation method thereof as well as application of S-1 full-silicon molecular sieve in caprolactam preparation

Abstract

The invention discloses an S-1 full-silicon molecular sieve and a preparation method thereof as well as application of the S-1 full-silicon molecular sieve in caprolactam preparation. The S-1 full-silicon molecular sieve is prepared by the method comprising the following steps: (1) synthesizing a tetrapropylammonium hydroxide template agent; and (2) synthesizing a molecular sieve: carrying out a reaction on tetrapropylammonium hydroxide liquor and tetraethoxysilane and ethanol, filtering, washing with deionized water, drying reaction liquid, roasting, so as to obtain molecular sieve raw powder; adding silica sol, polyethylene glycol 2000, and stronger ammonia water, sesbania powder and activated carbon powder in the molecular sieve raw powder, kneading in a kneader, then carrying out extrusion; roasting, immersing the roasted product in a NH3-NH3NO3 mixing solution and a hydrofluoric acid solution respectively, washing with deionized water, drying, roasting again so as to obtain the S-1 full-silicon molecular sieve. In the invention, the template agent is cheap; the conversion rate of the cyclohexanone and selectivity of the caprolactam are extremely high; a catalyst can be easilyand fast regenerated; and the use of concentrated sulphuric acid is avoided, thus the S-1 full-silicon molecular sieve and the preparation method thereof are environment-friendly.

Description

technical field [0001] The invention belongs to the technical field of petrochemical catalysis, and specifically relates to a pilot-scale process for producing caprolactam by using S-1 all-silicon molecular sieve to perform Beckmann gas-phase rearrangement. Background technique [0002] Caprolactam is an important chemical raw material and a monomer for the synthesis of nylon 6 and engineering plastics. Currently, there are two main processes for the synthesis of caprolactam, liquid-phase and gas-phase Beckmann rearrangement. At present, in industrial production, sulfuric acid is mainly used to catalyze the liquid phase rearrangement process. The process is that cyclohexanone oxime undergoes a Beckmann rearrangement reaction at a certain temperature under the action of concentrated sulfuric acid or oleum, and then uses ammonia to neutralize the acidity of the reaction system to generate caprolactam. The process technology is relatively mature, the reaction conditions are m...

AI Technical Summary

Problems solved by technology

Although since the 1980s, people have reduced the use of sulfuric acid and the generation of ammonium sulfate by changing the reactor form and process conditions, but the problems caused by the use of sulfuric acid have not been fundamentally resolved.

However, the current bottlenecks that plague the industrialization of this process are: (1) S-1 all-silicon molecular sieve is easily inactivated, low in selectivity and difficult to regenerate in the reaction of synthesizing caprolactam; Ammonium hydroxide is either low in quality or expensive (a 20% aqueous solution is probably as high as several thousand yuan per kilogram), which seriously restricts the large-scale preparation of molecular sieve catalysts

[0004] In summary, the use of S-1 all-silicon molecular sieve catalysts for gas-phase Beckmann rearrangement to produce caprolactam has good application prospects. However, due to some problems in the production process of S-1 all-silicon molecular sieves, the current research on this process is still not possible. To achieve a better reaction effect, or still remain in the stage of small laboratory tests, there is still a long way to go before industrialization

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