醋酸铜热解制备无氯Cu2O/AC催化剂及其催化氧化羰基化

以醋酸铜为前驱物, 采用浸渍法负载后进行热处理使醋酸铜热解, 获得了负载型无氯Cu2O/AC(活性炭)催化剂, 并通过催化甲醇直接气相氧化羰基化合成碳酸二甲酯(DMC). 在氮气和惰性气体气氛下, 一水合醋酸铜Cu(CH3COO)2·H2O在30~450 ℃范围内产生3个失重过程, 其中在150~300 ℃范围内Cu(CH3·COO)2热解生成Cu2O; 而在300~450 ℃范围内生成单质Cu. 在200~350 ℃范围内, 将Cu(CH3COO)2·H2O/AC加热处理4 h后, 催化剂上逐步形成了Cu2O, 到350 ℃时, 水合醋酸铜几乎全部转化为Cu2O, 并有极少量单质Cu形成. 在300~350 ℃热处理4 h后, 催化剂中铜主要以Cu2O形式存在, 并表现出良好的氧化羰基化催化活性. 在n(CO)∶n(MeOH)∶n(O2)=4∶10∶1及SV=5600 h-1条件下, 于300 ℃热处理4 h所制备的催化剂的甲醇转化率达到6.21%, DMC的时空收率为128.16 mg·g-1·h-1, 选择性为64.26%.

Chloride-free Cu_2O/AC Catalyst Prepared by Pyrolysis of Copper Acetate and Catalytic Oxycarbonylation

The chloride-free Cu2O/AC catalyst was prepared via pyrolysis of copper acetate supported on active carbon Cu(CH3COO)2/AC and used to catalyze vapor-phase oxycarbonylation of methanol to dimethyl carbonate(DMC). The Cu(CH3COO)2/AC precursor was prepared by the incipient wetness impregnation. When Cu(CH3COO)2·H2O was heated from 30 ℃ to 450 ℃ under inert nitrogen atmosphere, it decomposed successively to Cu(CH3COO)2, Cu2O and Cu, corresponding to three chemical processes. Cu2O was obtained at 150—300 ℃ heating temperature, and Cu was formed at 300—450 ℃. When Cu(CH3COO)2·H2O/AC was heated at 200—350 ℃ for 4 h, Cu2O was gradually formed on the surface of AC. The Cu2O/AC catalyst with predominant Cu2O and only a little Cu was obtained when Cu(CH3COO)2·H2O/AC heated at 350 ℃ for 4 h. It was observed that the Cu2O/AC catalyst heat-treated at 300—350 ℃ for 4 h exhibited very high catalytic activity for methanol oxycarbonylation. On the conditions of n(CO)∶n(MeOH)∶n(O2)=4∶10∶1 and SV=5600 h-1, and in the presence of Cu2O/AC catalyst prepared at 300 ℃ for 4 h, the methanol conversion, the space time yield and the selectivity of DMC was reached 6.21%, 128.16 mg·g-1·h-1 and 64.26%, respectively.