The Study Of Catalyst For Ethylene Prepared From Dimethyl Ether

The use of methyl oxygenates such as dimethyl ether(DME)and methanol to produce olefins(MTO,MTP)has become an important achievement in C1 chemical industry in the past decade.The technical route has opened up the production of olefins from coal and natural gas,and has diversified raw materials for olefin production.At the same time,it has good economics and has developed rapidly in ChinaThe existing methanol to olefins(ethylene+ propylene)carbon-based selectivity of MTO and MTP is usually not more than 80%.Although the olefin yield can be slightly increased by catalytically cracking the C4+components,there are still many C4+components,and the product composition is quite complicated,so the later product separation process required is quite longThis thesis explores the use of DME as raw material high-selective to ethylene by DME catalytical dehydration,screens a catalyst capable of producing more ethylene,studies the process conditions and reaction mechanism.Through the work of this research,the following main findings were obtained(1)The reaction of DME to ethylene on some basic catalysts,transition metal oxide catalysts and acidic molecular sieve catalysts were investigated by temperature programmed surface reaction(TPSR).It was found that an in-situ synthesized A-MOR-S0.1 molecular sieve had a strong ethylene response signal,and further chromatographic quantitative analysis also proved that the catalyst had good ethylene selectivity(2)The research on the content and method of doping promoter A in MOR shows that the in-situ synthesis method is superior to the impregnation method and ion exchange method.When the amount of promoter A doping is 0.1%,the selectivity of ethylene in the product is the highest,up to 50%,and the selectivity of diene(ethylene+ propylene)is more than 60%.(3)The catalyst evaluation tests of DME to olefin on A-MOR-S0.1 molecular sieve catalyst shows that the catalyst optimized operating conditions are the pre-reduction temperature of 230?,the reaction temperature of 400?,atmospheric pressure,and the space velocity of 600 h-1.Through the characterization of the catalyst samples,combined with the evaluation results,the reaction mechanism of DME to ethylene on A-MOR-S was discussed.