Enhanced Low-Temperature Dry Reforming of Methane over Ni/MCF Catalysts via Photothermal Synergy

Dry reforming of methane (DRM) is an effective reaction for reducing CO2 emissions while producing syngas. Since DRM is a highly endothermic reaction, it requires high temperature and a large amount of heat supply to maintain a high conversion of reactants. However, a high reaction temperature can cause catalyst sintering and severe carbon deposition. To reduce the reaction temperature and improve the reaction efficiency, photothermal synergistic catalysis has been introduced into the DRM reaction and has gradually become an important development direction. In this paper, a unique catalyst of Ni supported on siliceous mesostructured cellular foams (MCFs) with different pore sizes has been employed for photothermal DRM. Due to the smaller band gap of Ni/MCF, it has greater potential to generate photoelectrons and holes. As a result, MCFs with pore diameters larger than 15 nm as a support are more conducive in promoting the DRM under the synergistic effect of light and heat. During the thermal catalytic (TC) process, Ni/MCF begins to exhibit activity at 500 °C, while under light irradiation, the activation temperature of the catalyst significantly decreases to 250 °C, which is attributed to the localized surface plasmon resonance (LSPR) effect of metal Ni. Under the TC conditions, Ni/MCF has no activity at 450 °C, while under the photothermal synergistic catalytic (PTSC) conditions, the conversions of CH4 and CO2 at the same temperature exceeded 70%. Compared to the TC conditions, when the CO2 conversion reaches 80% under the PTSC conditions, the reaction temperature of DRM can be sharply reduced by about 150 °C. Conversions of 84.93, 90.33, and 95.54% are obtained for CO2, respectively, at 500, 550, and 600 °C by using 1%Ni/MCF as a catalyst under photothermal conditions, which are 2.0, 1.4, and 1.2 times higher than those under conventional thermal DRM. Moreover, 1%Ni/MCF exhibits excellent long-term stability at least for 50 h during PTSC DRM. These results indicate that the photothermal synergistic effect is conducive to enhancing catalytic performance while reducing energy consumption, and achieving much more efficient DRM at lower temperatures.