Research On The Reaction System Of Synthesis Gas-to-Dimethyl Ether

Dimethyl ether is an important chemical product and potential clean energy, with wide application in many industrial fields. The direct conversion of synthesis gas-to-dimethyl ether (STD) is of great academic and economic value, because it is greatly favorable in thermodynamics.In this dissertation, the influence of STD reaction condition, the interaction between two components of the double-function catalyst, the improvement of catalytic activity for the double-function catalyst etc were systemically studied.Based on the data of thermodynamic equilibrium model and actual reaction, the influence of feed gas and catalyst composition on the methanol synthesis and WGS reaction within this reaction system were analyzed in detail.A CuZnMnAl methanol synthesis component with high activity for STD catalyst was exploited and studied. It was found that in a proper adding range, manganese was rather efficient to increase the activity of CuZnAl catalyst. A novel preparation method of hydrothermal treatment was put forward. The preparation of methanol synthesis catalyst was simplified and the catalytic activity was enhanced.The methanol dehydration activities of many kinds of solid acid were investigated. By using ZSM-5 zeolites with different acidity, the influence of acidic amount and the acid properties on the whole activity of STD catalyst were studied in detail. The results indicated that, based on a certain amount of methanol synthesis component, there should be an optimum range of acidic amount tomatch for obtaining the best activity. The influence of zeolite on the activity of CuZnAl was very significant and should not be ignored.Metal-containing zeolite of Cu-ZSM-5 and Zn-ZSM-5 were initially synthesized directly by hydrothermal method, using [Me(NH₃)₄]²⁺ solution, fumed silica, and n-butylamine etc as resources. They were firstly applied as methanol dehydration component in STD reaction. It was found that the Cu-ZSM-5 exhibited excellent dehydration activity, while the Zn-ZSM-5 showed rather low activity. Combined with a series of characterization (XRF, XRD, SEM, 29Si and ²⁷Al MAS NMR, NH₃-TPD, and so on), the reason for the difference between their catalytic activity was discussed in detail. Furthermore, the moderate or strong acid sites may be account for the methanol dehydration in STD reaction.