Synthesis of Polyoxymethylene Dimethyl Ethers with HMCM-22 Zeolite Loading Phosphotungstic Acid as Catalyst
1.School of Chemical and Pharmaceutical Engineering, Hebei University of Science and Technology, Shijiazhuang 050018, China; 2. Shijiazhuang Gongda Chemical Equipment Company Limited, Shijiazhuang 050011, China
Abstract In order to increase the acidity of HMCM-22 catalyst and its catalytic performance for synthesizing of polyoxymethylene dimethyl ethers(DMMn), the acidity of HMCM-22 was enhanced by the method of loading phosphotungstic acid (PW) on it. Over the obtained PW/HMCM-22 catalyst, the synthesis of DMMn was studied by using methanol and trioxane as raw materials. The effect of the loading amount of PW, the calcining temperature and the calcining time on the catalytic performance were also investigated. The results show that the optimal preparation conditions are the mass loading amount of catalyst of 30%, the calcining temperature of 300 ℃ and the calcining time of 4 h. A higher catalytic activity of PW/HMCM-22 can be achieved under the optimal preparation conditions, and the conversion of trioxane and the selectivity of DMM2-8 are 87.12% and 54.84% respectively. After reusing five times, the catalytic performance of the catalyst has only little change, which indicates that the stability of the catalyst is perfect.
