钯催化气相氧化羰基化合成碳酸二甲酯

通过催化剂反应性能和反应前后XPS谱图对比，分析了负载型钯催化剂在甲醇气相氧化羰基化合成碳酸二甲酯过程中的失活原因，研究了HCl在维持催化剂活性及失活催化剂再生中的作用．结果表明，氯离子的流失是负载型钯碳催化剂失活的主要原因．由于氯离子的流失，对于PdCl2／AC催化剂，钯很容易从二价变为零价：对于PdCl2-CuCl2／AC催化剂，CuCl2发生变化，失去使钯保持二价氯化物状态的功能．在反应过程中补充HCl可以延长催化剂的寿命，也可以利用HCl对失活催化剂进行再生，但采用HCl不能从根本上解决催化剂失活的问题．

Oxidative Carbonylation for Dimethyl Carbonate Synthesis in Gaseous Phase over Supported Palladium Catalysts

The deactivation mechanism of the supported palladium catalyst for oxidative carbonylation of dimethyl carbonate synthesis from methanol in gaseous phase was studied according to the catalytic reaction behaviors and the XPS spectra for Pd species before and after the reaction. The effects of HCl on the suppression of Pd catalyst deactivation and the regeneration of deactivated catalyst were investigated. It was revealed that the primary reason for the catalyst deactivation was the loss of chlorine, which led to Pd~0 formation from Pd~(2+) at the PdCl_2/C catalyst and led to CuCl or Cu formation from CuCl_2 at the PdCl_2-CuCl_2/C catalyst. Although the presence of HCl during the reaction can delay the catalyst deactivation and promote the deactivated catalyst regeneration, it cannot regenerate the deactivated catalyst completely.