Advance in Hydrothermal Bio-Oil Preparation from Lignocellulose: Effect of Raw Materials and Their Tissue Structures

Libo Zhang,Xiao Yang,Zhilin Yang,Xuqiang Guo,Xintong Dou

doi:10.3390/biomass1020006

Abstract

The conversion of abundant forest- and agricultural-residue-based lignocellulosic materials into high-quality bio-oil by the mild hydrothermal method has great potential in the field of biomass utilization. Some excellent research on biomass hydrothermal process has been completed, including temperature, time, catalyst addition, etc. Meanwhile, some research related to the biomass raw material tissue structure has been illustrated by adopting mode components (cellulose, hemicellulose, lignin, protein, lipid, etc.) or their mixtures. The interesting fact is that although some real lignocellulose has approximate composition, their hydrothermal products and distributions show individual differences, which means the interaction within biomass raw material components tremendously affected the reaction pathway. Unfortunately, to our knowledge, there is no review article with a specific focus on the effects of raw materials and their tissue structure on the lignocellulose hydrothermal process. In this review, research progress on the effects of model and mixed cellulose/hemicellulose/lignin effects on hydrothermal products is initially summarized. Additionally, the real lignocellulosic raw materials structure effects during the thermal process are summed up. This article will inspire researchers to focus more attention on wood fiber biomass conversion into liquid fuels or high-value-added chemicals, as well as promote the development of world energy change.

Highlights

Human beings have fully realized that using fossil energy is clearly not sustainable, the reality is that fossil fuels, coal, oil, and natural gas account for more than80% of the world’s energy needs [1]
Lignocellulose is mainly composed of cellulose, hemicellulose, and lignin
This study concluded that the hydrogen bond between cellulose and hemicellulose affects its reaction activity in hydrothermal reactions, which in turn affects the characteristics of HT bio-oil and product distribution, suggesting that physical properties between raw material components, together with chemical properties, are major factors that determine the production of HT bio-oils

Summary

Introduction

Human beings have fully realized that using fossil energy is clearly not sustainable, the reality is that fossil fuels, coal, oil, and natural gas account for more than. The main research directions on bio-oil production from bioresources HTL process include temperature investigation, reaction time inspection, catalysts addition, and operation mode change (such as heating method), etc. Ravneet and Thallada [24] examined the effects of hydrothermal temperature and reaction time on HT bio-oil yield and conversion rate using castor residue as a raw material (Figure 1). Some interesting facts found are that many feedstocks contain approximate compositions (cellulose/hemicellulose/lignin content), but their performances during conversions exhibit tremendous differences under similar operation conditions, including products yields, compounds, etc. All those differences indicate that the inherent interaction could affect biomass feedstocks’ hydrothermal process and reaction pathway. The possibility of obtaining high HT bio-oil yield with high quality under relatively mild operation parameters by adjusting the raw materials’ tissues structures is encouraged

Structure of Plants

Research Progress on the Effect of Lignocellulosic Tissue Structures on Their

Real Biomasses and Their Structure Effects on Their HT Bio-Oil Preparation

Findings

Conclusions and Outlook