Direct Synthesis Of Dimethyl Ether By Catalytic Hydrogenation Of Carbon Dioxide

Carbon dioxide is one of the main greenhouse gases and the richest carbon source in the world. Exploiting and How to use CO2 is one of the most promising studies in modern industry technology. Catalytic hydrogenation of CO2 to form dimethyel ether (DME) is an important way, which not only can relieve the contamination of CO2, but also can obtain the valuable chemicals and fuels of DME. This synthetic technology will surely bring a remarkable environmental and economic efficiency, especially to those chemical plants producing a large number of by-products of CO2 and H2.Preparation of dimethyl ether by hydrogenation of CO2 is a complex chemical process, including two main steps of CO2 hydrogenation and methanol dehydration. In this paper, thermodynamics, kinetics, reaction mechanism and catalyst research for the synthesis of dimethyl ether from carbon dioxide hydrogenation were reviewed, and the following works were done:Acid modified montmorillonite loaded CuO-ZnO-Al2O3 by coprecipitation method was prepared. It was characterized by the methods of XRD and FT-IR. Catalytic activity of CuO-ZnO-Al2O3 modified montmorillonite for the synthesis of dimethyl ether from hydrogenation of CO2 was studied in the differential fixed-bed reactor and the effects of the reaction temperature, pressure and the components of catalyst on the catalytic activity were investigated under the conditions of H2 /CO2 = 3(volume ratio) and airspeed = 1600 h-1. The result shows that the conversion of CO2 can be reached to 26.5%, the selectivity and yield of dimethyl ether can be reached to 16.4% and 4.4%, respectively under pressure at 3 MPa and temperature at 533K.Acid modified montmorillonite loaded uniform gel of CuO-ZnO-Al2O3-Cr2O3 was prepared and characterized by the methods of XRD,TG/DSC. It was used for the hydrogenation of CO2 to form dimethyl ether. Acidified montmorillonite can effectively accelerate dehydration of methanol to dimethyl ether. Effect of acid concentration and calcination temperature on modified polygorskite, also as the temperature and the pressure on CuO-ZnO-Al2O3-Cr2O3 modified montmorillonite on hydrogenation of CO2 to dimethyl ether were investigated, respectively. CuO-ZnO-Al2O3-Cr2O3 modified montmorillonite shows the highest activity as montmorillonite is acidified by 1.0 mol/L HCl solution and is dried at 343 K. The result shows that the conversion of CO2 can be reached to 28.0%, the selectivity and yield of dimethyl ether can reached to 21.5% and 6.0%, respectively under pressure at 3 MPa and temperature at 545 K.