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Boron-doped graphene as a metal-free catalyst for gas-phase oxidation of benzyl alcohol to benzaldehyde

Cheng, Wenjun, Liu, Xueting, Li, Na, Han, Jiatong, Li, Shuangming, Yu, Sansan
RSC advances 2018 v.8 no.20 pp. 11222-11229
X-ray photoelectron spectroscopy, active sites, aerobic conditions, benzaldehyde, benzyl alcohol, boron, catalysts, catalytic activity, dehydrogenation, gases, graphene, moieties, oxidation
Boron-doped graphene samples (BGs) with tunable boron content of 0–2.90 at% were synthesized and directly used in the gas-phase oxidation of benzyl alcohol to benzaldehyde, and showed excellent performance. XPS results indicated that the graphitic sp² B species (BC₃) is the mainly boron dopant species incorporated in the graphene lattice, which could significantly improve the content of ketone carbonyl groups (CO) on the graphene. For instance, the contents of CO jumped from 1.93 to 4.19 at% while BC₃ doped into the graphene lattice was only 0.35 at%. The CO is the active site of catalytic reaction, so BG has significantly improved catalytic activity. Compared to the un-doped graphene (G), the conversion of benzyl alcohol over BGs increased 2.35 times and the selectivity of benzaldehyde increased from 77.3% to 99.2%. Aerobic–anaerobic exchange experiments revealed that the superior catalytic performance of BG was achieved only under aerobic conditions. The study of the boron-doped carbocatalyst may also provide guidance for the design of surface modified carbon-based catalysts for the selective oxidation dehydrogenation of alcohols by regulating doping elements and their types.