Photoinduced Dry and Bireforming of Methane to Fuels over La‐Modified TiO₂ in Fixed‐Bed and Monolith Reactors

Abstract

A systematic investigation on the performance of fixed‐bed and monolithic reactors for dynamic photoinduced CO2 reduction with CH4 via dry and bi‐reforming of methane over La‐modified TiO2 nanocatalyst under UV light is conducted. La/TiO2 is synthesized using a modified sol–gel method, and the monolithic‐coated catalyst is synthesized using a dip‐coating method. The performance of La/TiO2 is tested for different reforming systems in both types of photoreactors. The results reveal 5 wt% La/TiO2 effectively promotes CO2 and CH4 conversion to CO, H2, and C2H6, whereas catalyst performance is greatly enhanced in the presence of H2O in both types of reactors via bireforming of methane (BRM). Lower temperature is favorable for CO production, whereas H2 and C2H6 yields are enhanced at higher temperature. Notably, the monolith photoreactor is favorable for enhanced CO and H2 yields. More interestingly, quantum yield (QY) for H2 in BRM using monolith photoreactor is 1.402%—an increment of almost 4.99‐fold than dry reforming of methane (DRM). This can be attributed to enhanced CO2 adsorption with hindered charge recombination by La, appropriate redox potentials, larger illuminated surface area, and higher photon flux. The prolonged La/TiO2 activity in a monolith photoreactor for enhanced CO and H2 production signifies its potential for CO2 conversion applications.

Titanium Carbide (Ti3C2) MXene as a Promising Co-catalyst for Photocatalytic CO2 Conversion to Energy-Efficient Fuels: A Review

“…The photocatalysis process has great potential in promoting reactions that cannot occur in normal conditions . Reforming reactions, such as the dry reforming reaction, shown in eq , and bi-reforming reaction using water, shown in eq , require semiconductors with high oxidative photocatalytic activity for breaking the C–H bond of methane (CH 4 ) . Also, it needs higher ability of reduction for water splitting.…”

“…193 Reforming reactions, such as the dry reforming reaction, shown in eq 1, and bi-reforming reaction using water, shown in eq 2, require semiconductors with high oxidative photocatalytic activity for breaking the C− H bond of methane (CH 4 ). 194 Also, it needs higher ability of reduction for water splitting. Therefore, wide bandgap semiconductors comprising of strong redox potential for reforming technology are highly demanding.…”

Recent Developments in Natural Gas Flaring Reduction and Reformation to Energy-Efficient Fuels: A Review

“…The reason behind the higher activity can be attributed to a higher surface area, higher dispersion of the Ni catalyst, and a smaller particle size. On the basis of various studies it can be concluded that noble metals have strong resistance against carbon deposition; however, their cost limits application at an industrial scale. , It is suggested that for higher catalytic activity of Ni-based catalysts, the addition of noble and non-noble metals can be useful for enhanced catalytic performance of Ni catalysts with more resistance to carbon deposition. Other parameters such as support selection, preparation method, and catalyst promoter have greater potentials toward maximizing catalyst performance …”

Photocatalytic and Thermocatalytic Conversion of Methane

“…The preparation of syngas (CO, H 2 ) from photocatalytic CRM is also an important research topic, and many researchers have been making unremitting efforts to improve the quantum efficiency of the reaction process. [ 136–141 ] For example, Hu and co‐workers reported an efficient visible‐light photocatalytic CRM process by combining a Pt/black TiO 2 catalyst with the light‐reflecting surface of a SiO 2 substrate. [ 142 ] This process exhibits a high quantum efficiency of 32.3% at 550 °C and 57.8% at 650 °C under visible‐light irradiation ( Figure a,b).…”