Bio-Butanol Production on Heterogeneous Catalysts: A Review

Background: The demand for renewable fuels has taken on a new dimension, traceable to climate crisis. Liquid biofuels are one of the many arrays of renewable forms of energy that have taken center stage in replacing conventional fossil-based liquid fuels. Bioalcohols, alcohols produced from biomass resources, are regarded as promising substitutes for gasoline. Among bioalcohols, bioethanol has been most widely used for blending with gasoline; however, its high affinity for water and vapor pressure are the major drawbacks to its use as a gasoline blend agent. Biobutanol is considered a more promising liquid biofuel than bioethanol because of its higher research octane number, lower vapor pressure and volatility, and more flexible fuel blends. Biobutanol is typically produced via fermentation, which has drawbacks of byproduct formation, resulting in a low butanol yield. Therefore, isobutanol production via nonfermentative chemical routes using heterogeneous catalysts has gained increasing attention. Methods: In this article, we review the latest research on heterogeneous catalysis-based biobutanol production. Given current research output, up-to-date overview of the heterogeneous catalytic production of butanol from different renewable feedstocks (e.g., bioethanol, biomass-derived syngas, and organic waste-derived butyric acid) using various heterogeneous catalysts including supported metal and solid acid–base catalysts is provided. The future perspective of isobutanol production using metal nanoparticles is also discussed. Significant findings: In catalytic isobutanol production based on heterogeneous catalysis, butanol can be obtained from three feedstocks: ethanol derived from sugar biomass, syngas produced by biomass gasification, and volatile fatty acids (e.g., butyric acids) obtained by anaerobic digestion of organic waste. Compared with catalytic performance studies, the catalyst stability and durability in the biobutanol production have been relatively rarely studied.