Preparation Of Modified Zeolite Catalyst And Its Catalytic Performance On Methanol To Hydrocarbon

Methanol is an important link connecting coal resources and clean energy,which is widely used.A large number of coal-to-methanol projects are put into operation,causing a serious excess of methanol production capacity.The methanol-to-hydrocarbon production process can consume excess methanol production capacity and has better economic benefits.The methanol-to-gasoline process is a coal-based route for obtaining gasoline and can reduce the dependence on foreign oil.HZSM-5 catalyst are modified with transition metals to improve catalyst performance.The MTG kinetics of the modified zeolite was studied to obtain catalyst dynamics related parameters to guide the modification of the MTG reactor and optimize the reaction conditions.In this paper,HZSM-5,Fe-HZSM-5 and Zn-HZSM-5 molecular sieves were prepared by in-situ synthesis and characterized by XRF,XRD and BET.In the fixed-bed adiabatic reactor,the activity of Fe-HZSM-5 and Zn-HZSM-5 zeolites was evaluated under the exclusion of internal and external diffusion effects.Based on this,the thermodynamics of MTG reaction was investigated and the reaction kinetics of methanol to gasoline with the best Fe-HZSM-5 and Zn-HZSM-5 zeolite catalysts were studied.The results of the study are as follows:(1)On the 3.62wt%Fe-HZSM-5 catalyst the selectivity of gasoline is the highest,the life of the catalyst is longer and the content of aromatics in liquid hydrocarbons is lower.Therefore,the MTG kinetics of 3.62wt%Fe-HZSM-5 zeolite was studied using the three-lumped kinetic model constructed by Chen and Reagan.The resulting reaction rate expressions are k1= 0.921 x 1012exp(-108600//RT).k2 = 0.155 x 1012exp(-116400/RT)andk3 = 1.008 x 107exp(-96130/RT).The model can accurately describe the MTG kinetics on Fe-HZSM-5 catalysts.(2)The kinetics of MTG reaction catalyzed by 2.54wt%Zn-HZSM-5 zeolite was significantly higher than other Zn content Zn-HZSM-5 catalyst.Therefore,the kinetics of methanol to gasoline on this catalyst was studied.The three-lumped kinetic reaction rate of expressions k1 = 1.154 x 1012exp(-97600//RT)?k2 = 0.687 x 1012exp(-105200/RT)and k3 = 1.739 × 107exp(-84700//RT).At different temperatures,the experimental values and the simulated values of each component in the space-time increase trend are basically consistent.Therefore,the three-lumped kinetic model can express the kinetic behavior of methanol to gasoline on Zn-HZSM-5 zeolite catalysts.