Study On The Solid Acid Catalyst For One-Step Synthesis Of Dimethyl Ether

In contrast of conventional "two-step" DME synthesis process, direct synthesis of DME from syngas, which has an inherent advantage in technology and economy, comes to become the research topic recently. In the synthesis reaction, using a dual-function catalyst that both have methanol synthesis and methanol dehydration. In the current production process, the point of research is to finding a kind of solid acid dehydration catalyst that have suitable acidic, acidity for high activity, high selectivity to match the reaction temperature of copper-based methanol synthesis catalyst.The synthesis and processing conditions of the bifunctional catalyst for dimethyl ether were studied by using fixed bed reactor in the paper. Comparisoning of different types of solid acid catalyst performance by CO conversion and DME selectivity. Based on the new bi-functional catalyst developed, composite modified zeolite FER by metal ions Zn²⁺, Mn²⁺ and composite modifiedγ-Al₂O₃ by Ni²⁺, S₂O₈^2-, what is more mixture of solid acid were studied.Through carries on Zn²⁺, Mn²⁺ composite modified FER, the effect of soaking temperature, soaking concentration, soaking time and composite metal ion concentrationand calcination temperature on the solid acid catalytic properties are studied. Through analyze the result, knew the law of change modification conditions impact on catalytic properties of solid acid, at the same time get the best conditions for the composite modified. The experimental results indicated that the optimal modification conditions are Zn²⁺, Mn²⁺ solution dipping time 3.5h, dipping temperature 80℃, the concentration of Zn²⁺, Mn²⁺ are 4% and 2%, calcination temperature is 450℃.Through carries on Ni²⁺, S₂O₈^2- composite modifiedγ-Al₂O₃, the effect of soaking temperature, soaking concentration, soaking time and composite metal ion concentrationand calcination temperature on the solid acid catalytic properties are studied, knew the acid and the amount of variation of acid onγ-Al₂O₃. The experimental results indicated that the optimal modification conditions are Ni²⁺, S₂O₈^2- solution dipping time 3h, dipping temperature 80℃, the concentration of Ni²⁺, S₂O₈^2- are 15% and 1%, calcination temperature is 450℃.Under these conditions, the conversion of CO can be achived 73.1%, the DME selectivity 46%.Basd on the preparation of modification solid acid Zn-Mn/FER and S₂O₈^2--Ni²⁺/γ-Al₂O₃, mixture of these two solid acid. Through carries on changeing reaction temperature and complex ratio, investigate Catalytic properties of composite solid. Through analyze the result, knew the effect of reaction temperature and the different of complex ratio on Catalytic properties of composite solid. And synthesize high activity compositesolid acid at low reaction temperature. The result of experimental indicated that the compositesolid acid S₂O₈^2--Ni²⁺/γ-Al₂O₃-Zn/Mn/FER(20%) need lower reaction temperature and improve the selectivity of target products and reduce the selective of by-product.