Regulation of partial oxidation in biochar-catalyzed tar reforming for hydrogen upgrading in syngas: The effect of oxygen concentration

Effective methods for maintaining catalyst activity in tar reforming have been a major focus during the development of biomass gasification technology. The role of partial oxidation in regulating the catalytic efficiency of biochar in tar reforming was investigated using a fluidized bed/fixed bed reaction system. The physico-chemical structures of biochar were characterized by FTIR, Raman, nitrogen adsorption and thermosgravimetry analysis. The tar characterization was analyzed by GC-MS and the production of gas components was monitored on-line with synthetic gas analyzer. The results reveal that partial oxidation regulation (0.2 % - 0.4 % O-2) can potentially maintain the biochar's catalytic efficiency and facilitates the production of hydrogen in gas. The addition of oxygen effectively inhibits the coke deposition on biochar. As the O-2 concentration is increased to 0.4 %, the total conversion of tar increasing to a maximum of 0.056 g/g, an increase of 27 % compared to the absence of oxygen. The H-2 yield is also increased to a maximum of 0.523 L/g. When the O-2 concentration is further enhanced (similar to 0.6 %), more H-2 is consumed by oxygen, the H-2 yield is reduced and the tar conversion capacity of biochar is significantly weakened. Partial oxidation regulation maintains the pore structures of the biochar, but there is a conversion of microporous pores to meso-macroporous pores. Partial oxidation regulation effectively inhibits the loss of O-containing structures on biochar, but also contributes to its increased graphitization.

Automated summary

The role of partial oxidation in regulating the catalytic efficiency of biochar in tar reforming was investigated. It was found that increasing the oxygen concentration effectively inhibits coke deposition and maintains the catalytic efficiency of biochar. However, excessive oxygen concentration weakens the tar conversion capacity of biochar.