Potential use of alkaline hydrogen peroxide in lignocellulosic biomass pretreatment and valorization - A review

Alkaline hydrogen peroxide (AHP) was first introduced in 1984. Its ability to selectively attack carbonyl and ethylene groups is proven to enhance the delignification process of lignocellulosic biomass. The capabilities of AHP in dissociating the recalcitrant matrix of biomass indicate its potential in improving the accessibility of biomass to achieve valorization. In this paper, the background information of AHP and its reaction pathways are provided. Moreover, the recent applications of AHP in biomass processing and biofuel production are discussed by highlighting the effects of AHP in process selectivity and biomass dissolution. This paper also aims to provide some insights on the advantages and disadvantages of utilizing AHP in a pretreatment process. Lastly, a technoeconomic and cost benefit analysis of two scenarios of AHP production are critically reviewed to highlight the feasibility of implementing AHP in large scale production. It was reported that, AHP pretreatments were compatible with wide range of biomass and subsequent enzymatic hydrolysis. Besides, it was found that the application of AHP sequential pretreatment of biomass could increase the production yield of various bio-products such as silica and lignin. On top of that, AHP pretreatment was found to be a mild pretreatment method that promoted inherent safer and greener process. However, the mild operation condition would require a prolonged period to achieve the necessary delignification. Through technoeconomic analysis, the high chemical cost has rendered the installation of recycle stream compulsory to achieve economic feasibility.