Applied Fundamental Study On Catalytic Conversion Of Methanol To Aromatics

MTA?Methanol to Aromatics?process has greatly realistic and strategic significance.As we all know,conventional aromatics mainly originate from petroleum routes.However,our country face serious import situation with the increase of aromatic demand.Furthermore,the production capacity of methanol becomes significantly large,only less than 60 % of which still run on stream.Based on present energy situation in our country which is abundant with coal and lack petroleum and gas,it is necessary to develop the clean MTA process.MTA process can both reduce the strategic risk of importing oversea aromatics and relieve the excess situation of production capacity of methanol.First of all,present research applied HZSM-5 catalyst as research object.We investigated the effect of reaction conditions,such as reacton temperature,methanol feed rate,and catalyst loadng amount,on the MTA reaction performance on a continuous fixed bed setup.The experimental result shows that high temperature is conducive to the enhancement of aromatic contents in gasoline.However,secondary reaction,such as cracking reaction of gasoline fractions deepens as the reaction temperature increases.Based on above two factors,the final aromatic yields remained constant.The nature of changing methanol feed rate and catalyst loading amount is to adjust WHSV of the reaction.Cutting down WHSV of reaction is able to contribute to the final aromatization process of intermediates,such as light olefins.The introduction of Al₂O₃ can markably elavate the aromatic yields.The addition of Al₂O₃ can produce mesopores which are able to reduce the diffusion resistance,and therefore promoting the diffusion of aromatics.Furthermore,Al₂O₃ can both modulates the ration of Lewis and Bronsted acid and increases the density of mid-strong acid and strong acid.The above mentioned aspects might be some important factors for enhancing aromatic yields.Present research investigatd the effect of Zn or Ni alone modified HZSM-5 or HZSM-5-Al catalysts on the MTA reaction performance.The experimental results show that appropriate loadig of Zn or Ni loading can enhance the aromatic yields and aromatic contents in gasoline.In addition,according to the reaction performance and characterization of Zn/HZSM-5-Al or Ni/HZSM-5-Al catalysts,Zn or Ni and Al₂O₃ can produce synergistic effect on MTA reaction performance,and therefore enhance the aromatic yields.Above all,appropriate reaction conditions,Zn or Ni loading,and presence of Al₂O₃ can significantly improve the aromatic yields.However,the investigation about the catalysts is still limited,which needs further research and enhancment.