Review of chemical pretreatment of lignocellulosic biomass using low-liquid and low-chemical catalysts for effective bioconversion

•Pretreatment improves conversion through degradation of recalcitrant structures.•Pretreatment facilitates in modification of crystalline structure of cellulose.•Pretreatment facilitates recovery of hemicellulose and lignin from biomass.•Amount of liquid and catalyst used is an important factor in efficiency and cost.•Low -liquid method aids to reduce inhibitor formation, corrosion, and energy cost.