Development Of Solid Acid Catalyst For Alkylation Of Benzene And Dodecene

Linear alkylbenzene is obtained by the alkylation reaction between long-chain olefins and benzene.It is a raw material for the main detergent component of synthetic detergents.Since it has been put into large-scale industrial production,its production technology has been continuously researched and developed.At present,the market share of the HF catalytic production process developed by UOP reaches more than 90%,but HF is highly corrosive,and there are problems such as high requirements for production equipment,complicated process flow,and serious environmental pollution.Therefore,it has been replaced by various solid acid catalysts.HF acid catalyst has become the research focus of the new process for the synthesis of linear alkylbenzenes.At present,the Detal solid acid alkylation technology developed by UOP has the problems of short catalyst single-pass life and frequent regeneration.The zeolite ratio of Beta zeolite can range from a dozen to pure silicon,with moderate acidity and good stability.It has a three-dimensional twelve-membered ring channel system,which is good for alleviating the problem of catalyst deactivation caused by zeolite blockage.effect.In this paper,the conventional hydrothermal synthesis of Beta zeolite was first performed.The effects of mold silicon ratio,water silicon ratio,alkali silicon ratio,and crystallization time on Beta zeolite synthesis were investigated.Beta zeolite with different silica-alumina ratios were also synthesized.Properly increasing the amount of template agent,reducing the amount of water,increasing the amount of alkali,and extending the crystallization time are beneficial for the synthesis of Beta zeolite,and under this condition,the range of the silica-alumina ratio for the synthesis of Beta zeolite can be narrow.Then,based on the conventional hydrothermal synthesis,the research on the solid-phase synthesis of Beta zeolite was carried out.The effects of the mold silicon ratio,water silicon ratio and alkali silicon ratio on the synthesis of Beta zeolite were also studied.Consistent.When investigating the effect of changing the segmented crystallization time on the synthesis of Beta zeolite,when the crystal growth time is shortened,the crystals cannot grow normally.The optimal crystallization time is140 ? for 24 hours and 160 ?for 24 hours.On this basis,Beta zeolites with different silica-alumina ratios were synthesized.It is known through analysis that the grain size is small,the average grain size is between 250-550 nm,and the specific surface area and pore volume are large.Finally,the alkylation reaction evaluation was carried out on a fixed-bed microreactor.The effects of reaction temperature,pressure,styrene ratio and space velocity on the alkylation reaction were mainly investigated using n-dodecene and benzene as raw materials.Too high or too low temperature and pressure will shorten the life of the catalyst.Properly reducing the space velocity and increasing the styrene ratio will help to extend the life of the catalyst.With the increase of the silicon-aluminum ratio,the life of the catalyst is reduced from 24 h to 14 h,and the catalyst is stable.The activities in the stage are relatively high,and the conversion rate of dodecene has basically reached 100%.Through the deactivation research of the catalyst,it can be found that the main reason for the deactivation of the catalyst is that the alkyl benzene of the product and impurities in the raw material block the catalyst pores.The catalyst activity can be completely restored by hot benzene flushing for 24 hours.