The Catalytic Conversion Of Simulated MTP Byproducts Over Modified Hierarchical ZSM-5 And Its Kinetics Study

Coal-base methanol to propylene(MTP)is an important alternative route to petroleum route.Lots of byproduct from MTP is paid close attention when the MTP process was commercially run.Maybe converting them to light olefins,especially propylene,is economic and reasonable.However,the new catalyst is needed to develop urgently due to the complexity and difference of feed in components.The present work focuses on this problem to carry out the studies of catalyst modification and its kinetics for the understanding of reaction essence and for the optimization of catalyst and reaction conditions.The elemental modification was carried out by using IWI method and hierarchical ZSM-5 zeolite was prepared by alkali treatment(AT)to obtain AT-ZSM-5 and P-AT-ZSM-5.The relative characterizations showed that alkali treatment decreased the strong acid amount and created new mesopores,while the elemental modification adjusted the acid properties.The modification by P for hierarchical ZSM-5 not only decreased the strong acid amount but also changed some mesopores to micropores.The influences of elemental modification on catalytic cracking performance were investigated.Among them,modified by P gave high selectivity and yield of light olefins,especially propylene.The changes in strong acid amount greatly influence the conversion and product distributions.Kinetics experiments of catalytic cracking were carried out in a micro fixed bed,and the six lumped kinetic model had been built with well goodness of fit by the aid of MATLAB software.The results indicated that both catalyst properties and reaction conditions influence the catalytic performance.The catalyst for high yield of light olefins,especially for propylene,need to be modified by element(s)and suitable mesopores in size and capacity.Of course,the suitable reaction conditions such as temperature,space velocity,diluent,and so on will further increase the yield of light olefins.