Efficient catalytic conversion of corn stalk and xylose into furfural over sulfonated graphene in γ-valerolactone

Raw biowaste conversion to high-value compounds for food, cosmetic and pharmaceutical industries

Biowaste valorisation into high-value compounds is one of the main challenges of green chemistry, as chemicals produced from biological sources are identified as key substances in the development of a low-carbon and circular bioeconomy in connection with the transition from fossil to renewable feedstocks. The review summarizes the production of high-value products such as glucose-based chemicals, phenolic compounds and volatile-fatty acids prepared from biomass waste. Biowaste pretreatment methods such as milling, filtration and extraction followed by current non-catalytic methods such as microwave or ultrasound extraction and catalytic methods for the production value-added compounds in the presence of various catalyst types in conventional, nano or enzyme form are listed with a focus on value-added chemicals applied in the food, cosmetic and pharmaceutical industries. The economic feasibility, technical aspects and concept of the biorefinery are briefly mentioned, emphasizing the necessity of life cycle assessment for each bioproduct and technological process. Finally, it provides a future perspective and makes recommendations for potential research strategies, recognizing the importance of utilizing biomass waste for the production of useful compounds as an attractive and environmentally friendly approach whose development should be encouraged. The utilization of biowaste for high-value chemicals production shows high potential, however, there are still many challenges to be resolved throughout the entire production chain, reflecting technological, economic, ecological, sociological and long-term issues.

Current Status and Challenges for Metal-Organic-Framework-Assisted Conversion of Biomass into Value-Added Chemicals

Owing to the abundance of availability, low cost, and environmental-friendliness, biomass waste could serve as a prospective renewable source for value-added chemicals. Nevertheless, biomass conversion into chemicals is quite challenging due to the heterogeneous nature of biomass waste. Biomass-derived chemicals are appealing sustainable solutions that can reduce the dependency on existing petroleum-based production. Metal-organic frameworks (MOFs)-based catalysts and their composite materials have attracted considerable amounts of interest in biomass conversion applications recently because of their interesting physical and chemical characteristics. Due to their tunability, the catalytic activity and selectivity of MOF-based catalyst/composite materials can be tailored by functionalizing them with a variety of functional groups to enhance biomass conversion efficiency. This review focuses on the catalytic transformation of lignocellulosic biomass into value-added chemicals by employing MOF-based catalyst/composite materials. The main focus is given to the production of the platform chemicals HMF and Furfural from the corresponding (hemi)cellulosic biomass, due to their versatility as intermediates for the production of various biobased chemicals and fuels. The effects of different experimental parameters on the conversion of biomass by MOF-based catalysts are also included. Finally, current challenges and perspectives of biomass conversion into chemicals by MOF-based catalysts are highlighted.

Efficient synthesis of furfurylamine from biomass via a hybrid strategy in an EaCl:Gly-water medium

The objective of this work was to develop an efficient approach for chemoenzymatically transforming biomass to furfurylamine by bridging chemocatalysis and biocatalysis in a deep eutectic solvent of EaCl:Gly-water. Using hydroxyapatite (HAP) as support, heterogeneous catalyst SO4 2-/SnO2-HAP was synthesized for transforming lignocellulosic biomass into furfural using organic acid as a co-catalyst. The turnover frequency (TOF) was correlated with the pKa value of the used organic acid. Corncob was transformed by oxalic acid (pKa = 1.25) (0.4 wt%) plus SO4 2-/SnO2-HAP (2.0 wt%) to produce furfural with a yield of 48.2% and a TOF of 6.33 h-1 in water. In deep eutectic solvent EaCl:Gly-water (1:2, v/v), co-catalysis with SO4 2-/SnO2-HAP and oxalic acid was utilized to transform corncob, rice straw, reed leaf, and sugarcane bagasse for the production of furfural with the yield of 42.4%-59.3% (based on the xylan content) at 180°C after 10 min. The formed furfural could be efficiently aminated to furfurylamine with E. coli CCZU-XLS160 cells in the presence of NH4Cl (as an amine donor). As a result of the biological amination of furfural derived from corncob, rice straw, reed leaf, and sugarcane bagasse for 24 h, the yields of furfurylamine reached >99%, with a productivity of 0.31-0.43 g furfurylamine per g xylan. In EaCl:Gly-water, an efficient chemoenzymatic catalysis strategy was employed to valorize lignocellulosic biomass into valuable furan chemicals.

Biomethane production by typical straw anaerobic digestion: Deep insights of material compositions and surface properties

Straws as lignocellulosic agricultural biomass have a huge amount and are widely used for biomethane production by anaerobic digestion (AD). However, the mechanism of impacts of straw composition and surface properties on biomethane production remain unclear. Here, a lab-scale AD incubation experiment was conducted and the characterization of four types of straws (corn straw, wheat straw, sweet sorghum straw, and rice straw) were also determined. The straw compositions and net cumulative methane production showed significant difference. Although the relative contents of key organic components and carbon had no significant correlation to the biomethane production (r = -0.36, P > 0.05), there existed differences of non-polar characteristics, steric hindrance effect and special surface morphology in four types of straws, indicating that the surface characteristics affected anaerobic biomethane production process. In addition, the straw matrix associating with silicon might hinder the biotransformation.