Unraveling the promoting roles of sulfate groups on propane combustion over Pt-SO42-/ZrO2 catalysts

Pt-SO42-/ZrO2 catalysts with different SO(4)(2-)contents were employed for propane combustion. Addition of SO42- significantly improved the catalytic activity for propane combustion, such as the Pt-5SO(4)(2-)/ZrO2 catalyst gave the highest turnover frequency (TOF) of 0.56 s(-1) at 200 degrees C, while the pristine Pt/ZrO2 catalyst gave a TOF of only 0.020 s-1. Strong coordination between Pt and SO(4)(2-)species resulted in drastic suppression of CO adsorption capacity (from 36.8 to 6.0 mu mol g(cat)(-1)), and increased Pt-0 ratio in the spent PtSO42-/ZrO2 catalysts. The exposed Pt sites on the Pt/ZrO2 and Pt-SO42-/ZrO2 catalysts show comparable reactivity for C-H activation as evidenced by the methane combustion, and the sulfate species are not helpful in C-H bond cleavage. The enhanced catalytic activities on Pt-SO42-/ZrO2 catalysts for propane combustion are mainly ascribed to the higher reactivity for C-C bond activation promoted by the synergistic catalysis of Pt species with superacid sites. Whereas, such synergy is affected by the amount of SO42- because the excessive SO42- would reduce the exposed Pt sites. (c) 2022 Elsevier Inc. All rights reserved.

Automated summary

Pt-SO42-/ZrO2 catalysts with different SO42- contents were used for propane combustion. The addition of SO42- significantly improves the catalytic activity by promoting the synergy between Pt species and superacid sites for C-C bond activation. However, excessive SO42- reduces the exposed Pt sites.