With the draining of petroleum derivatives, expanding natural contamination issues, there has been rising enthusiasm for the examination of lignocellulosic biomass for an alternative fsource of energy. Characterization of various biomass, its intermediate, and products is a need for conversion of any biomass to biofuels. Chemical composition of lignocellulosic biomass is an essential point for developing potent pretreatment technologies to break its rigid structure, conversion of sugar by different enzymes mainly cellulose to glucose and even various microorganisms which can ferment sugars into bioethanol and other value-added green chemicals. In this present review work, the main focus is on the proximate and ultimate analysis of different feedstocks, and altered pretreatment techniques such as physical, chemical, physicochemical, and biological methods for bioethanol production have been addressed, which ultimately will help in overcoming the recalcitrance of lignocellulosic biomass by degrading the lignin fraction, breaking down of lignocellulose components, hydrolysis, and fermentation process. Recently, combined pretreatment is gaining popularity as it is more favorable and profitable for improving chemical yield and process of enzymatic hydrolysis of LBs, but it increases the cost of operation. Acid pretreatment, steam explosion, and hydrothermal processes all together show a comparatively high effect on degrading hemicelluloses fraction. Alkali, oxidative, and organosolv pretreatment are more efficient in removing and degrading of lignin portion. This present study will empower a better idea and knowledge of the available process with the upcoming advanced processes which would help to overcome the limitations and establish technology to facilitate the pretreatment methods to make an authentic concept of biorefinery.

随着石油衍生物的排放，自然污染问题的扩大，人们对木质纤维素生物质作为替代能源的研究热情不断提高。表征各种生物质，其中间体和产品是将任何生物质转化为生物燃料的需要。木质纤维素生物质的化学组成是开发有效的预处理技术的关键点，该技术可以打破其刚性结构，通过不同的酶（主要是纤维素将酶转化为葡萄糖）将糖转化为糖，甚至可以将糖发酵为生物乙醇和其他增值绿色化学品的各种微生物。在目前的审查工作中，主要重点是对不同原料的近距离和最终分析，以及改变的预处理技术，例如物理，化学，物理化学，已经提出了用于生物乙醇生产的生物方法，并且其最终将通过降解木质素部分，分解木质纤维素成分，水解和发酵过程来帮助克服木质纤维素生物质的难降解性。近来，组合预处理越来越受欢迎，因为它对于提高LB的化学收率和酶促水解工艺更为有利和有利可图，但它增加了操作成本。酸预处理，蒸汽爆炸和水热过程共同显示出对降解半纤维素部分的较高效果。碱，氧化和有机溶剂预处理在去除和降解木质素部分方面更有效。