Photothermal steam reforming: A novel method for tar elimination in biomass gasification

Tar elimination is the bottleneck which hinders the industrial application of gasification due to the risks of corrosion and blockage in downstream components. Tar production decreases the energy efficiency of gasification systems. The steam reforming is attractive for tar treatment, but the high reaction temperature limits its applications. Photothermal catalysis has the potential to decompose organic pollutants, and it is expected to improve tar removal and reduce the reaction temperature. So, the photothermal steam reforming of toluene was performed to evaluate the toluene conversion. The effects of the toluene concentration, the temperature, the steam to carbon ratio, and the ultraviolet light intensity were investigated. The results showed that, compared with the thermal steam reforming, the photothermal steam reforming could significantly improve the conversion of toluene and promote the formation of gaseous products, especially H2. At 600 °C, the conversion of toluene in the photothermal steam reforming was 90.1%, which was 16.3% higher than that in the thermal steam reforming. Moreover, the mechanisms of the photothermal steam reforming were revealed. The introduction of the ultraviolet irradiation could strongly promote the toluene decomposition and alter the reaction pathways. The carbon deposition and agglomeration of the catalyst were inhibited in photothermal steam reforming. Meanwhile, the toluene removal performance and the energy consumption were compared in photothermal and thermal steam reforming. The potential applications of photothermal catalytic tar removal were also described. These findings proposed a novel approach for low-cost but high-efficiency biomass tar removal, thus promoting the clean utilization of biomass energy.