Platinum‐ and CuO_x‐Decorated TiO₂ Photocatalyst for Oxidative Coupling of Methane to C₂ Hydrocarbons in a Flow Reactor

Abstract

Oxidative coupling of methane (OCM) is considered one of the most promising catalytic technologies to upgrade methane. However, C 2 products (C 2 H 6 /C 2 H 4) from conventional methane conversion have not been produced commercially owing to competition from overoxidation and carbon accumulation at high temperatures. Herein, we report the codeposition of Pt nanoparticles and CuO x clusters on TiO 2 (PC-50) and use of the resulting photocatalyst for OCM in a flow reactor operated at room temperature under atmospheric pressure for the first time. The optimized Cu 0.1 Pt 0.5 /PC-50 sample showed a highest yield of C 2 product of 6.8 mmol h À1 at a space velocity of 2400 h À1 , more than twice the sum of the activity of Pt/PC-50 (1.07 mmol h À1) and Cu/PC-50 (1.9 mmol h À1), it might also be the highest among photocatalytic methane conversions reported so far under atmospheric pressure. A high C 2 selectivity of 60 % is also comparable to that attainable by conventional high-temperature (> 943 K) thermal catalysis. It is proposed that Pt functions as an electron acceptor to facilitate charge separation, while holes could transfer to CuO x to avoid deep dehydrogenation and the overoxidation of C 2 products.

Molecular oxygen enhances H2O2 utilization for the photocatalytic conversion of methane to liquid-phase oxygenates

“…Harsh reaction conditions, such as high temperatures 6 – 8 and/or high pressures 9 – 15 , are required for traditional heterogeneous thermocatalytic selective conversion of methane. Recently, photocatalysis has been explored for selectively converting methane mainly to valuable liquid oxygenates at room temperature and ambient pressure 16 – 24 .…”

Solar driven efficient direct conversion of methane to multicarbon oxygenates

“…However, TiO 2 possesses a wide band gap, leading to insufficient visible light absorption and rapid recombination of photogenerated carriers. [16][17][18][19] Thus, extensive efforts to modify the electronic band structures of TiO 2 for visible light harvesting are being made, and composites of TiO 2 coupled with nanoscale carbonaceous materials have exhibited promising potential. [16][17][18][19] Here, we show that by tuning the band structures of TiO 2 supported on reduced graphene oxide (RGO), CH 4 can be selectively and efficiently converted into multicarbon products under simulated solar irradiation using only water vapor as an oxidant.…”

“…[16][17][18][19] Thus, extensive efforts to modify the electronic band structures of TiO 2 for visible light harvesting are being made, and composites of TiO 2 coupled with nanoscale carbonaceous materials have exhibited promising potential. [16][17][18][19] Here, we show that by tuning the band structures of TiO 2 supported on reduced graphene oxide (RGO), CH 4 can be selectively and efficiently converted into multicarbon products under simulated solar irradiation using only water vapor as an oxidant. We demonstrate that the synergistic effect between the p-pconjugated substrate of RGO and oxygen vacancies (O-vacancies) of TiO 2 can expand the visible light absorption and improve the efficiency of photogenerated charge separation and transfer.…”

“…However, TiO 2 possesses a wide band gap, leading to insufficient visible light absorption and rapid recombination of photogenerated carriers. 16–19 Thus, extensive efforts to modify the electronic band structures of TiO 2 for visible light harvesting are being made, and composites of TiO 2 coupled with nanoscale carbonaceous materials have exhibited promising potential. 16–19…”

“…16–19 Thus, extensive efforts to modify the electronic band structures of TiO 2 for visible light harvesting are being made, and composites of TiO 2 coupled with nanoscale carbonaceous materials have exhibited promising potential. 16–19…”