Rong Zhang, Xi Yang, Zheng Tao
Nov 20, 2019
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0
Influential Citations
12
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Journal
ACS applied materials & interfaces
Abstract
Boron nitride (BN) has attracted great attention with unexpected ability in aerobic catalysis. Still, its related probe reactions are relatively rare, and the effect of BN supported metal catalyst on O2 activation is still ambiguous and opinions are varied. In this work, porous BN (pBN) supported Au catalyst with porous structure and exposed edges exhibits high activity in the oxidative cross-esterification reactions between aromatic and C1-C3 aliphatic alcohols at ambient temperature. The turnover frequency value for methyl benzoate is 118 h-1 at 30 °C and the calculated apparent activation energy (Ea, 58 kJ/mol) is comparable to that of AuPd/TiO2, Ru/Al2O3 and PdBiTe catalysts. Combined with TPD results, the loading of Au enhances desorption of O2 and the interaction with alcohols, thus a synergistic effect between the O-rich pBN and Au is considered. The free-radical scavenger can dramatically suppress the conversion (~6%) suggesting that the reaction proceeds via the O2* radicals. According to the vibration of νO-O, δOO-H and vB-O-O-B detected by ATR-IR, we prone to consider the oxygen activation route by the edge B atoms. Then a possible L-H reaction mechanism was proposed: benzyl alcohol and O2 adsorb on the Au/pBN initially; then O2 is converted to O2*, and the α-H elimination proceeds; as the semi-acetal formed, another α-H termination proceeds and methyl benzoate is finally formed.