Effects of Sugars, Furans, and their Derivatives on Hydrodeoxygenation of Biorefinery Lignin-Rich Wastes to Hydrocarbons

Purification and Fractionation of Lignin via ALPHA: Liquid-Liquid Equilibrium for the Lignin-Acetic Acid-Water System

In order to effectively practice the Aqueous Lignin Purification with Hot Agents (ALPHA) process for lignin purification and fractionation, the temperatures and feed compositions where regions of liquid-liquid equilibrium (LLE) exist must be identified. To this end, pseudo-ternary phase diagrams for the lignin-acetic acid-water system were mapped out at 45-95 °C and various solvent: feed lignin mass ratios (S : F). For a given temperature, the accompanying SL (solid-liquid), SLL (solid-liquid-liquid), and one-phase regions were also located. For the first time, ALPHA using acetic acid (AcOH)-water solution was applied to a lignin recovered via the commercial LignoBoost process. In addition to determining tie-line compositions for the two regions of LLE that were discovered, the distribution of lignin and key impurities (the latter can negatively impact lignin performance for materials applications) between the two liquid phases was also measured. As a representative example, lignin isolated in the lignin-rich phase was reduced 7x in metals and 4x in polysaccharides by using ALPHA with a feed solvent composition of 50-55 % AcOH and an S : F of 6 : 1, with said lignin being obtained at a yield of 50-70 % of the feed lignin and having a molecular weight triple that of the feed.

A novel mechanocatalytical reaction system driven by fluid shear force for the mild and rapid pretreatment of lignocellulosic biomass

Pretreatment is the initial stage of lignocellulosic biorefinery process, but is limited by the time-consuming processes, harsh conditions and/or undesirable products. Herein, a mild (<60 °C) and highly efficient pretreatment strategy is developed. The novel mechanocatalytical reaction system driven by fluid shear force helps to exfoliate cellulose from lignocellulose, and the heat generated by the shear process can be used to precipitate and recover the dissolved cellulose from the precooled NaOH/urea solution. The regenerated cellulose shows satisfying crystal structure (cellulose II), significantly decreased crystallinity and nearly tripled enzymolysis glucose yield. Almost 90% of lignin and hemicellulose could be rapidly separated. The separated lignin shows a nearly native structure with 64% β-O-4 linkage, which is even higher than the ball-milling lignin (60%). This research provides a theoretical guidance for the mild pretreatment of lignocellulosic biomass, which will push the application of mechanocatalytical reaction system in biorefinery processes on a large scale.

Ru-gC3N4 Catalyzed Hydrodebenzylation of Benzyl Protected Alcohol and Acid Groups Using Sodium Hypophosphite as a Hydrogen Source

A straightforward process for hydrodebenzylation of benzyl protected acid and alcohol derivatives to the corresponding acids and alcohols using sodium hypophosphite in the presence of Ru-GCN catalyst is reported. The developed Ru-GCN catalyst is cost effective compared to other noble metal-based catalysts and has been explored to exhibit excellent activity for catalytic hydrodebenzylation reactions under moderate reaction conditions. The non-corrosive sodium hypophosphite has been found as a better hydrogen donor compared to alkali metal formats in presence of Ru-GCN catalyst. The stated catalyst was characterized using several spectrometric and material characterization methods such as PXRD, IR, SEM, TEM, XPS, and TGA. The Ru-GCN catalyst corroborated good reusability and stability for multiple cycles. The catalyst preparation is facile and the developed process is simple and safe as it avoids use of high hydrogen pressure. The developed protocol can also be replicated on industrial scale on account of excellent recyclability and retained activity after multiple cycles and makes the process sustainable. Gram scale reaction was performed to verify the industrial potential of reported catalyst.

Tumor microenvironment-responsive, high internal phase Pickering emulsions stabilized by lignin/chitosan oligosaccharide particles for synergistic cancer therapy

HYPOTHESIS

The stability of anti-cancer drugs and the adverse drug reactions (ADRs) caused by drug-drug interactions (DDIs) are two major challenges of combination chemotherapy. In this work, hydrophilic drug loaded lignin-based nanoparticles were applied to stabilize high internal phase Pickering emulsions (HIPPEs) containing hydrophobic drug in the oil phase, which not only improved the stability of anti-cancer drugs, but also reduced the risk of DDIs.

EXPERIMENTS

Highly biocompatible enzymatic hydrolysis lignin/chitosan oligosaccharide (EHL/COS-x) nanoparticles were prepared and used to load hydrophilic cytarabine (Ara-C). The morphology, loading capacity, encapsulation efficiency and emulsifying properties of nanoparticles were characterized and predicted. Subsequently, these nanoparticles were applied to stabilize HIPPEs with soybean oil containing hydrophobic curcumin as dispersed phase. The effects of the morphology, amphipathy and concentration of nanoparticles and oil/water ratio on the microstructure and stability of HIPPEs were investigated. Meanwhile, the controlled release, protective performance, cytotoxicity and bio-activity of HIPPEs were also evaluated.

FINDINGS

EHL/COS-x nanoparticles loaded with Ara-C could stabilize HIPEs with 85 vol% soybean oil containing curcumin. The two drugs were separately loaded in same delivery system, which effectively lowered the risk of DDIs. Meanwhile, HIPPEs provided outstanding UV, thermal and oxidation protection for these two environmentally sensitive anti-cancer drugs. In addition, HIPPEs displayed a good pH-responsive release in a tumor environment. In vitro experiments show that the killing efficiency of two drugs co-loaded HIPPEs against the leukemia cell is two times higher than that of single drug loaded systems. This strategy can be extended to the synergistic therapy of two or more drugs with different physicochemical properties.

Hydro(deoxygenation) Reaction Network of Lignocellulosic Oxygenates

Hydrodeoxygenation (HDO) is a key transformation step to convert lignocellulosic oxygenates into drop-in and functional high-value hydrocarbons through controlled oxygen removal. Nevertheless, the mechanistic insights of HDO chemistry have been scarcely investigated as opposed to a significant extent of hydrodesulfurization chemistry. Current requirements emphasize certain underexplored events of HDO of oxygenates, which include 1) interactions of oxygenates of varied molecular size with active sites of the catalysts, 2) determining the conformation of oxygenates on the active site at the point of interaction, and 3) effects of oxygen contents of oxygenates on the reaction rate of HDO. It is realized that the molecular interactions of oxygenates with the surface of the catalyst dominates the degree and nature of deoxygenation to derive products with desired selectivity by overcoming complex separation processes in a biorefinery. Those oxygenates with high carbon numbers (>C10), multiple furan rings, and branched architectures are even more complex to understand. This article aims to focus on concise mechanistic analysis of biorefinery oxygenates (C_10-35 ) for their deoxygenation processes, with a special emphasis on their interactions with active sites in a complex chemical environment. This article also addresses differentiation of the mode of interactions based on the molecular size of oxygenates. Deoxygenation processes coupled with or without ring opening of furan-based oxygenates and site-substrate cooperativity dictate the formation of diverse value-added products. Oxygen removal has been the key step for microbial deoxygenation by the use of oxygen-removing decarbonylase enzymes. However, challenges to obtain branched and long-chain hydrocarbons remain, which require special attention, including the invention of newer techniques to upgrade the process for combined depolymerization-HDO from real biomass.

Efficient hydrogenolysis of aryl ethers over Ce-MOF supported Pd NPs under mild conditions: mechanistic insight using density functional theoretical calculations

The significant Pd⁰ content and optimum bonding of the reactant & product (higher adsorption energy of benzyl phenyl ether and lower desorption energy for phenol) are responsible for the exceptional catalytic activity of Pd/Ce-MOF.