Abstract:
This article investigates the promoting effect of gallium (Ga) on the activity of Ga-WO
x/SBA-15 catalyst for
cis-cyclooctene epoxidation with H
2O
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
2O
2 on 0.3Ga-WO
x/SBA-15 surface, facilitating the H
2O
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.