Preparation Of Fe-K-Ce Catalyst For Dehydrogenation Of Ethylbenzene & Exploration Of Catalyst For Styrene Production By Side Chain Alkylation Of Toluene

Styrene is a basic and important chemical raw material in organic processes,which has been applied to synthesize a series of polymeric materials such as rubber and polyurethane.Styrene is industrially produced by dehydrogenation of ethylbenzene on Fe-K-Ce based catalysts,which should have high activity,selectivity,and stability.Compared to this traditional process,methylation of toluene by methanol is an energy saving,low cost,and mild reaction.Due to more surplus toluene and methanol,this methylation reaction has also become a hot research field.In this work,the effect of preparation method on the ethylbenzene dehydrogenation performance of Fe-K-Ce based catalysts was investigated and then the influence of metallic promoters was explored for methylation of toluene over modified 13X zeolite catalysts.The formation of crystal phase of potassium ferrate(K₂Fe₂₂O₃₄)is not sensitive to the preparation processes,while its crystallinity is different.After comparison of characteristics of the fresh and used catalyst,it was found that the crystals of CeO₂ after two-step calcinations method are smaller and the lattice oxygen is abundant.The density of the acid-base centers is also moderate;The catalyst has the strong resistance to coke formation.Therefore,the two-step calcinations method is suitable for preparation of Fe-K-Ce based catalysts,at an ethylbenzene conversion of 72%,with a styrene selectivity to 92.7%.After optimization of operation parameters,the dehydrogenation activity increased with the reaction temperature increasing.In order to optimize potassium,different potassium precursor was investigated further based on two-step calcination method.The results show that the dehydrogenation activities over the catalysts prepared from K₂CO₃,KOH and KNO₃ are better,and the conversions of ethylbenzene are 72%.While the catalysts prepared by potassium nepheline and potassium fulvic acid have detrimental effect on the formation of K2Fe22O₃4,the dehydrogenation activity was significantly reduced.So the K₂CO₃ is a suitable precursor.The surface of 13X molecular sieves were modified by different metal salts and used in the alkylation reaction of methanol to toluene side chains.The framework of the 13X zeolite was damaged varying degrees by adding of different metal promoter.Simultaneously,the acid-base centers were also modified depending on metal promoter.Mg neutralized part of weak acids,while Zn,Zr enhanced the acidity of support.The toluene conversion increased,while the selectivities to ethylbenzene and styrene is lower over the Zn and Cu modified catalysts.On the contrary,the toluene conversion decreased with the high selectivity to desired product over the Mg and Zr modified catalysts.How to improve toluene conversion and styrene selectivity through surface acid-alkaline modulation needs further exploration.