Study On Selection And Deactivation Of Catalysts In Methanol To Gasoline

The methanol,which as the bulk chemical raw material in methanol to gasoline,can effectively reduce the production cost of gasoline and meet the demand of market of large tonnage,especially in the current of the high sales and low prices of gasoline.Moreover,the methanol to gasoline has vital significance on enhancing the competitiveness of the methanol industry in China and soughting the new product ways for the high-speed construction of the large-scale methanol plants,because the reaction process is short,secure and controlled easily,and the installations are more flexible than the other processes.So the technology is very impressive and can meet completely the requirements of the green economy synthetic route.At present,although the well-functioning industrialization demonstration project for the methanol to gasoline has been built,a series of specific problems in the implementation process are presented,such as the easy deactivation and frequent regeneration for catalysts,large air circulation and high energy consumption.and so on.In view of the above problems,the paper discusses the deactivation cause,mechanism and catalytic properties of HZSM-5 catalyst,the main contents are as follows:1)The catalyst selection in the methanol to gasoline was investigated on a micro-fixed bed reactor.The results showed that the catalytic properties of the import,homemade No.1 and homemade No.2 catalytic were better.The three catalysts were characterized and found that the characteristic for the MTG catalyst:particle size 50¹00nm,SiO₂/Al₂O₃ 50⁸0,pore volume?0.3 cm³/g,relative crystallity?0.98,no residual templating agent.2)The re-DR-1 catalyst activity test was carried out under the same conditions.The results showed that the activity of the fresh re-DR-1 catalyst is well,but the stable performance is little better than the import catalyst.Meanwhile,the different gasoline products prepared by the four catalysts were analyzed,and the results found that the main hydrocarbons in the four products were iso-paraffins and aromatic,which are in line with the the national?,?quality index for vehicle gasoline,but the relative content were different,import>re-DR-1>homemade No.1>homemade No.2.3)Experimental results of that continuous operation showed that the catalytic activity of import HZSM-5 were relative stable when the reaction for 180 h,but the activity could drop obviously after 180 h.It was found that the coke was the main reason for catalyst deactivation,and the coke content reached up to 20.16%after 336 h for the reaction and the pores were clogged seriously.4)The catalysts were treated under the 600?high temperature hydrothermal conditions,it was found that the specific surface area of import catalyst decreased rapidly and then gradually leveled off as the treatment time under hydrothermal conditions,while under high temperature conditions the surface area firstly decreased and then increased.The decline may be due to the serious dealumination of HZSM-5 zeolite caused pore collapse,and the specific surface increased during the high temperature treatment because the new high specific surface area component was generated,such as?-Al₂O₃.