Melamine Modification of the Carrier Regulating the Performance of PtBi/AC in Heptanol Oxidation

Abstract

Different bimetallic platinum and bismuth catalysts supported on melamine‐modified activated carbon (AC) are designed by a co‐impregnation method. Through controlling the activation temperatures of the melamine‐AC mixture, a series of N‐doped and C3N4‐modified AC (N‐AC and C3N4‐AC) are prepared. Combined powder X‐ray diffractions, X‐ray photoelectron spectroscopic, and high‐angle annual dark field scanning transmission electron microscopic studies demonstrated that the introduction of C3N4 favors the formation of PtBi alloy and leads to increased particle sizes in comparison to the pristine and N‐doped AC‐supported bimetallics. The catalytic performance of the developed catalysts is evaluated in the oxidation of n‐heptanol oxidation in a batch mode using O2 as the oxidant. PtBi/C3N4‐AC exhibited significantly boosted activity as well as selectivity to heptanoic acid as compared with the other catalysts. A high yield of heptanoic acid of 69% can be achieved under the optimized reaction conditions. Furthermore, our work points to the PtBi alloy as the most active sites for the alcohol oxidation. Catalyst deactivation occurs in the cycling tests, mainly due to the collapse of the alloy phase and likely the decrease in particle sizes.