The Efficient and Sustainable Pyrolysis and Gasification of Biomass by Catalytic Processes

The biomass thermochemical conversion process includes two major approaches: pyrolysis and gasification. The advantages of pyrolysis and gasification of biomass feedstock in the presence of various catalyst systems are critically reviewed. The role of a catalyst in pyrolysis of biomass and its major components cellulose, hemicellulose and lignin is investigated. The discussion is focused on elucidating the reaction mechanisms involved in the formation of aromatics and phenols during catalytic pyrolysis. The pyrolysis performance of two major catalyst systems, metal-containing catalysts and zeolite catalysts, is analyzed. The impact of the catalyst on the deoxygenation efficiency is ascertained. In the catalytic gasification process, two major catalyst systems including alkali metals and noble metal catalysts are employed. This review illustrates the function of the catalyst in improving the yields of syngas and hydrogen and the mechanistic aspects of the reduction of tar and char formed during gasification. Ultimately, the review is intended to introduce the state of art in the biomass thermochemical conversion with an emphasis on the importance of the catalyst in producing value-added products.