Prepapation And Application Of Mesoporous CuO/γ-Al₂O₃ Catalyst For One-step Syngas To Dimethly Ether

Taking full advantage of coal resources, releasing the shortage of petroleum resources and realizing clean utilization of coal, syngas to dimethylether （STD） has attracted great attention. Preparation of composite catalysts with high activity and stability is essential to large-scale application of STD. These composite catalysts usually consist of two active components, i.e., catalysts for methanol synthesis and dehydration. Cu-based catalyst is employed for methanol synthesis. y-A;2O3 catalyst with low cost and large specific surface area is adopted for methanol dehydration.Applied to STD, CuO/γ-Al₂O₃ composite catalysts with mesoporous structure were prepared by solvent evaporation and combustion method. The results are as follows:（1） CuO/γ-Al₂O₃ composite catalysts with ordered mesoporous structure were prepared by solvent evaporation method. Cu was uniformly dispersed on the surface of γ-Al₂O₃. Cu content is inversely proportional to order degree of mesoporous structure. The highest CO conservation 72.2% and dimethyl ether （DME） selectivity 60.2% were achieved at 1500 h-1,320℃, and 5 MPa. The as-prepared CuO/γ-Al₂O₃ composite catalysts exhibited higher activity compared with ones with Zn as promoter, indicating Zn was not indispensable to catalysts for methanol synthesis.（2） CuO/γ-Al₂O₃ composite catalysts with mesoporous structure were prepared by combustion method using citric acid as combustion improver, copper nitrate and aluminum nitrate as raw materials. Cu was uniformly dispersed. The highest CO conservation 70.9% and DME selectivity 58.8% were achieved at 1500 h-1,320℃, and 5 MPa.（3） CuO/y-Al₂O₃ composite catalysts with obvious mesoporous structure were prepared by combustion method using urea as combustion improver, copper nitrate and aluminum nitrate as raw materials. Cu was uniformly dispersed. The highest CO conservation 52.9% and DME selectivity 66.1% were achieved at 260℃. After continuous reaction for 56 h, CO conservation dropped 5.2% achieving 47.7%, and methanol selectivity exhibited no noticeable decline, indicating high stability of the as-prepared CUO/γ-Al₂O₃ composite catalysts.CuO/γ-Al₂O₃ composite catalysts prepared by combustion method using urea as combustion improver exhibited regular structure, large specific surface area and high activity at 5℃/min and 800℃.