Ga对0.3Ga-WO_(x)/SBA-15催化顺式-环辛烯环氧化的促进作用

Role of Ga in promoting epoxidation of cis-cyclooctene over Ga-WO_(x)/SBA-15

本工作研究了镓(Ga)对Ga-WO_(x)/SBA-15催化H_(2)O_(2)与顺式-环辛烯环氧化反应活性的促进作用。最佳催化剂0.3Ga-WO_(x)/SBA-15的TOF为112 h^(-1),是WO_(x)/SBA-15(57 h^(-1))的近两倍。相较于WO_(x)/SBA-15(64.0 kJ/mol),0.3Ga-WO_(x)/SBA-15的低表观反应活化能(49.6 kJ/mol)与其优异的环氧化性能一致。动力学分析表明,H_(2)O_(2)在0.3Ga-WO_(x)/SBA-15表面上的吸附更强,这有助于H_(2)O_(2)的活化。基于催化剂的表征和环氧化的性能表明,Ga添加剂的提升作用归因于Lewis酸位点的增加和亲电性的增强。此外,金属过氧化氢(M-OOH)被鉴定为主要中间体。

This article investigates the promoting effect of gallium(Ga)on the activity of Ga-WO_(x)/SBA-15 catalyst for ciscyclooctene epoxidation with H_(2)O_(2).The optimal catalyst of 0.3Ga-WO_(x)/SBA-15 offered a turnover frequency(TOF)of 112 h^(-1),which was nearly two times than that of WO_(x)/SBA-15(57 h^(-1)).The low apparent reaction activation energy for 0.3Ga-WO_(x)/SBA-15(49.6 kJ/mol vs 64.0 kJ/mol for WO_(x)/SBA-15)was also in line with its superior performance.Kinetic analysis demonstrated stronger adsorption of H_(2)O_(2)on 0.3Ga-WO_(x)/SBA-15 surface,facilitating the H_(2)O_(2)activation.Based on the characterizations and catalytic performance,the improvement of Ga was attributed to the increase of Lewis acid sites and the enhancement of electrophilicity.Furthermore,the metal hydrogen peroxide(M-OOH)was identified as the primary intermediate.