摘要
采用活性炭(AC)载体浸渍醋酸铜,然后热分解制备甲醇气相氧化羰基化合成碳酸二甲酯的无氯Cu2O/AC催化剂.用硝酸或氨水处理活性炭后,其表面的化学性质发生了变化,从而影响了Cu2O/AC催化剂的结构和催化活性.实验结果表明,硝酸或氨水改性后的活性炭表面不仅有新的含氮基团产生,而且含氧基团C—O—C,C—O和CO—O增加,CO基团明显减少或消失.其中,含氮基团的供电子效应和富余的CO—O基团使负载在载体上的CuⅡ更容易被还原成CuⅠ,有利于获得组分单一且分散较好的Cu2O负载型催化剂,从而显著地提高了催化活性.氨水改性的活性炭更加有利于活性物种Cu2O的分散,能够进一步改善催化性能,在n(CO)∶n(MeOH)∶n(O2)=4∶10∶1,SV=5600h-1条件下,甲醇转化率达到7.0%,DMC的时空收率为145.1mg/(g.h),基于甲醇的选择性为68.7%.
The chloride-free Cu2O/AC catalyst was prepared by pyrolysis of copper acetate supported on active carbon（AC）, which was used to catalyze the direct vapor-phase oxycarbonylation of methanol to dimethyl carbonate （DMC）. When the AC support was treated with nitric acid or ammonia, the chemical property of AC surface was modified, resulting in the change of surface structure and high catalytic activity of Cu2O/AC catalyst. The experiments revealed that the new nitro-groups were formed and the oxy-groups （C-O-C, C--O and CO--O） increased, but the C =O species decreased significantly or disappeared on the surface of active carbon treated with nitric acid or ammonia. The reduction of Cu ^Ⅱ to Cu^Ⅰ was promoted by the nitro- groups electron donation and rich CO-O groups, which was propitious to obtain unique and well dispersed Cu2O supported catalysts and enhance the catalytic activity. The treatment of AC with ammonia was favor for the dispersion of Cu2O and improved catalytic activity furthermore. On the conditions of n（ CO）： n（ MeOH）： n（O2） =4： 10：1 and SV = 5600 h-1, the methanol conversion, the space time yield and the selectivity of DMC reached 7.0%, 145.1 mg/（g·h） and 68.7% , respectively.
出处
《高等学校化学学报》
SCIE
EI
CAS
CSCD
北大核心
2010年第1期145-152,共8页
Chemical Journal of Chinese Universities
基金
国家自然科学基金(批准号:20976113)
国家"九七三"计划项目(批准号:2005CB221204)资助
