Steam explosion of lignocellulosic biomass for multiple advanced bioenergy processes: A review

The utilization of lignocellulosic biomass to produce fuels and chemicals is an effective way to gradually relieve the global threats of petroleum exhaustion and climate change. However, the recalcitrant nature and complex structure of biomass have become the biggest obstacle for utilization during the bioenergy conversion processes. Steam explosion, a mild and fast treatment process integrating the high-temperature autohydrolysis and structural disruption by explosive decompression, has been proven as an effective, environment-friendly and industrially scalable method for biomass pretreatment, which can significantly improve the fuel properties and processability of the feedstock, for several bioenergy conversion techniques. This article aimed at reviewing the impact of steam explosion pretreatment on the bioenergy conversion processes and product properties. Based on those findings in the literature, a steam explosion step is beneficial to subsequent conversion processes of biomass, including densification, hydrolysis, fermentation, pyrolysis and gasification, by improving biomass properties such as durability, heating value and cellulose accessibility. Improved yields and properties of final products in solid (e.g. pellet fuel, biochar), liquid (e.g. bio-oil, bioethanol, biobutanol) and gaseous (e.g. syngas, biogas) states were also analyzed. Overall, this review provided a historical and comprehensive understanding of how the steam explosion benefits the subsequent bioenergy conversion process and product quality.