Engineering Innovations, Challenges, and Opportunities for Lignocellulosic Biorefineries: Leveraging Biobased Polymer Production

Abstract

Alternative polymer feedstocks are highly desirable to address environmental, social, and security concerns associated with petrochemical-based materials. Lignocellulosic biomass (LCB) has emerged as one critical feedstock in this regard because it is an abundant and ubiquitous renewable resource, which can be deconstructed to generate valuable fuels, chemicals, and small molecules/oligomers that are amenable to modification and polymerization. However, the diversity of LCB complicates the evaluation of biorefinery concepts in areas including process scale-up, production outputs, plant economics, and life-cycle management. We discuss aspects of current LCB biorefinery research with a focus on the major process stages, including feedstock selection, fractionation/deconstruction, and characterization, along with product purification, functionalization, and polymerization to manufacture valuable macromolecular materials. We highlight opportunities to valorize underutilized and complex feedstocks, leverage advanced characterization techniques to predict and manage biorefinery outputs, and increase the fraction of biomass converted into valuable products. Expected final online publication date for the Annual Review of Chemical and Biomolecular Engineering, Volume 14 is June 2023. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

Bio-Oil Production and Characterization from Corn Cob and Sunflower Stem Pyrolysis

“…Within the sustainable context, bioenergy has attained notorious attention for being carbon neutral and because of its vast availability, low-cost feedstock, multifaceted application, and reliability for operating on both small and large scales . In particular, the use of lignocellulosic agroindustrial residues as an energy source stands out for the potential to reduce the dependence on traditional fuels while helping to overcome the issues of proper crop residue management . The agricultural sector is responsible for producing more than 3.3 Gt fresh weight of stalks, straws, husks, leaves, and cobs, , which instead of being subtilized, burned, or simply discharged into the environment can be efficiently processed by several thermochemical technologies to be converted into easy-to-use forms of energy …”

“…4 In particular, the use of lignocellulosic agroindustrial residues as an energy source stands out for the potential to reduce the dependence on traditional fuels while helping to overcome the issues of proper crop residue management. 5 The agricultural sector is responsible for producing more than 3.3 Gt fresh weight of stalks, straws, husks, leaves, and cobs, 6,7 which instead of being subtilized, burned, or simply discharged into the environment can be efficiently processed by several thermochemical technologies to be converted into easy-to-use forms of energy. 8 Among thermal conversion methods, pyrolysis is conducted to access biomass potential by heating the carbonaceous feedstock to temperatures above 400 °C and under partial or total absence of an oxidizing agent.…”

Thermogravimetric Analysis as a High-Throughput Lignocellulosic Biomass Characterization Method

“…Lignocellulosic biomass (LCB) holds incredible promise as an alternative feedstock to petroleum for the production of materials, chemicals, and fuels. − In this regard, the rapid and accurate characterization of LCB is a critical step for biorefining because it enables biorefineries to quickly screen feedstocks, predict and manage biorefinery outputs, and optimize overall plant economics while minimizing environmental impacts. , LCB characterization primarily involves the quantification of three major componentscellulose (40–60 wt %), hemicellulose (10–40 wt %), and lignin (15–30 wt %) . Cellulose is a crystalline polymer composed of glucose monomers, whereas hemicellulose is an amorphous polymer composed of hexoses and pentoses.…”

“…As biorefineries scale up, high-throughput characterization methods (i.e., methods capable of rapidly screening a large number of samples) are needed to meet the increased volume of feedstocks, but current approaches are limited by intensive “wet-laboratory” (i.e., manual chemistry involving liquid reagents) procedures or low repeatability to meet biorefinery demands. ,,− The standard method for LCB characterization is a laboratory analytical procedure developed by the National Renewable Energy Laboratory (NREL). , The NREL procedure quantifies holocellulose by hydrolyzing it into monomeric sugars and analyzing the sugars via high-performance liquid chromatography and measures lignin via the Klason method, which is a gravimetric analysis approach . The procedure is accurate for evaluating holocellulose and lignin content in a range of woody biomass samples (i.e., hardwoods and softwoods). , However, the lignin is particularly challenging to characterize consistently because of its inherent complexity, and the NREL procedure also has increased error associated with feedstocks or feedstock components that contain higher levels of nonstructural components (e.g., proteins, waxes, suberin), such as in herbaceous (grassy) feedstocks. ,, Furthermore, the NREL method’s throughput is limited by its labor-intensive procedure, its accuracy is constrained by the analytical skills of the researcher(s) performing the characterizations, and its analysis provides limited structural information beyond the component abundances …”

Introduction to the RSC Advances themed collection Chemistry in Biorefineries

“…The biorenery concept, which takes traditional reneries as a starting point and adapts them to environmentally friendly processes based on bioresources as raw materials, has attracted signicant scientic interest during the last few years. 1 Bioreneries are a realistic alternative for producing the advanced biofuels, bio-based materials, and chemicals required in a post-petroleum scenario. 2 The residual lignocellulosic biomass generated by agriculture, forestry, crop processing, and other industries is a major feedstock base for bioreneries.…”