不同载体负载的Cu2(OH)3CI催化剂对甲醇氧化羰基化的催化性能

采用浆液浸渍法制备了小同载体负载的Cu2(OH)3Cl催化剂,考察了催化剂对甲醇氧化羰基化合成碳酸二甲酯(DMC)反应的催化性能.结果表明,各载体负载的Cu2(OH)3Cl催化剂活性均高于传统的负载CuCl2催化剂;以比表面积较大的活性炭(AC)为载体的催化剂活性最高.以Cu2(OH)3Cl/AC(w(Cu)=18.71%)为催化剂时,甲醇转化率、DMC选择性和DMC时宅收率可分别达到6.93%,67.3%和139.1mg/(g·h);其催化性能比较稳定,反应60h后其催化活性略有下降.通过CO程序升温脱附、X射线衍射、X射线光电子能谱和扫描电镜等技术对催化剂进行了表征.结果表明,在反应过程中催化剂的活性物种Cu2(OH)3Cl的晶粒逐渐团聚、长大,并且转化为CuCl2和CuO;同时,新鲜催化剂中唯一的CuⅡ物种部分转化为CuⅠ物种.

Catalytic Performance of Cu2(OH)3Cl Catalysts Supported on Various Supports for Methanol Oxidative Carbonylation

Supported Cu_2(OH)_3Cl catalysts were prepared by the slurry impregnantion method and used in MeOH oxidative carbonylation to dimethyl carbonate (DMC). The catalytic activity of Cu_2(OH)_3Cl supported on various supports was higher than that of supported CuCl_2, and active carbon (AC) was the suitable support because of its larger specific surface area. Cu_2(OH)_3Cl/AC (w(Cu) =18.71%) exhibited excellent catalytic performance. MeOH conversion, DMC selectivity, and DMC space time yield were 6.93%, 67.3%, and 139.13 mg/(g·h), respectively, and the catalyst was more stable. The supported catalysts were characterized by CO-temperature programmed desorption, X-ray diffraction, X-ray photoelectron spectroscopy, and scanning electron microscopy, showing that the higher dispersion of Cu_2(OH)_3Cl in Cu_2(OH)_3Cl/AC was getting worse and transformed to CuCl_2 and CuO during the reaction, resulting in the decrease of catalytic activity. The unique Cu~Ⅱ species in the fresh catalyst transferred into Cu~Ⅰ species partially during the reaction.