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In this work, a lignin-based concrete water reducer was prepared through organic solvent fractionation and chemical modification of lignin extracted from pine wood with formic acid. The fractionated lignin with different molecular weight was modified via oxidation–sulfomethylation (OS), and the effects of fractionation on the performance of lignin-based concrete water reducer were investigated. It was found that the sulfonation degree (SD) of the fractionated lignin after OS was clearly higher compared to the unfractionated lignin, and the SD of fractionated lignin was linearly correlated with its workability (i.e., the fluidity of cement paste) based on the results obtained. By adding the same quantity of modified lignin-based concrete water reducer, the fluidity of cement paste with the fractionated lignin (by pure acetone) after OS modification was 21% higher than the sulfonated FAL (M-FAL) without fractionation. The organic solvents used in this study could be easily recovered and reused. Thus, the whole fractionation process was sustainable. In addition, the structure changes of lignin samples before and after fractionation and OS modification were characterized by gel permeation chromatography, FTIR, and 1H NMR, respectively.

Carbon dioxide is a sufficient and important carbon resource, which has been widely used as a C1 building block in synthetic chemistry. Carbonylations with CO are important processes in industry. However, due to the toxicity of CO, its storage and transport are problematic. Attentions are gradually focused on using other safe reagents to be the CO surrogates in carbonylation reactions. This review focuses on the summary of recent developments in using CO2 as a CO surrogate in homogeneous catalysis. Reductive processes by using H2, Si‐H, alcohols, etc and redox‐neutral processes are separately summarized.

High‐performance transition metal chalcogenides (TMCs) as electrocatalysts for two‐electron oxygen reduction reaction (2e‐ORR) in alkaline medium are promising for hydrogen peroxide (H 2 O 2 ) production, but their synthesis remains challenging. In this work, a titanium‐doped zinc–cobalt sulfide hollow superstructure (Ti–ZnCoS HSS) is rationally designed as an efficient electrocatalyst for H 2 O 2 electrosynthesis. Synthesized by using hybrid metal–organic frameworks (MOFs) as precursors after sulfidation treatment, the resultant Ti–ZnCoS HSS exhibits a hollow‐on‐hollow superstructure with small nanocages assembled around a large cake‐like cavity. Both experimental and simulation results demonstrate that the polymetallic composition tailors the d‐band center and binding energy with oxygen species. Moreover, the hollow superstructure provides abundant active sites and promotes mass and electron transfer. The synergistic d‐band center and superstructure engineering at both atomic and nanoscale levels lead to the remarkable 2e‐ORR performance of Ti–ZnCoS HSS with a high selectivity of 98%, activity (potential at 1 mA cm −2 of 0.774 V vs reversible hydrogen electrode (RHE)), a H 2 O 2 production rate of 675 mmol h –1 g cat –1 , and long‐term stability in alkaline condition, among the best 2e‐ORR electrocatalysts reported to date. This strategy paves the way toward the rational design of polymetallic TMCs as advanced 2e‐ORR catalysts.

Based on radical sulfur dioxide insertion and fluorination strategy, we have developed an efficient method for aliphatic sulfonyl fluoride synthesis from abundant carboxylic acid, reductant, sulfur dioxide surrogate and electrophilic...

The development of an economic and sustainable catalytic system was crucial for lignin-based biorefinery. Herein, we reported a low-cost Cu/CuMgAlO x catalyst with promising activity toward lignin hydrodeoxygenation (HDO) through a H2-free method. Supercritical methanol was used as the hydrogen donor, solvent, and reactant simultaneously. Guaiacol was employed as a representative lignin model compound to reveal the HDO mechanism of lignin derivatives. HDOs of guaiacol performed at 250, 275, 300, and 350 °C with durations ranging from 15 to 120 min indicated a high HDO efficiency of the catalytic system. The obtained liquid products were categorized to oxygen-containing unsaturated products (OUPs), oxygen-containing saturated products (OSPs), and cycloalkanes. A kinetic model based on a simplified reaction process containing the three following conversion steps was established: guaiacol transformed to OUPs through the initial HDO, then hydrogenated to OSPs (medium HDO), and eventually turned to cycloalkanes by the deep HDO. The deep HDO was the rate-determining step, and the apparent activation energies of the three steps were all lower than those in the literature. Phenol, 1,2-cyclohexanediol, anisole, and veratrole were the major intermediates, the HDOs of which were programed for pathway verification. Remarkably, catechol (the culprit of condensation) was not produced in this system. Overall, a detailed reaction network of guaiacol HDO was established, and the veil of Cu/CuMgAlO x -catalyzed lignin-derivatives HDO in supercritical methanol was revealed. This work paved the way for the application of Cu/CuMgAlO x catalyst in lignin-derivatives upgrading.

Lignin represents the most abundant and sustainable aromatic resource to produce value-added aromatics. However, an efficient and selective cleavage of recalcitrant C–C bonds in lignin under mild conditions remains challenging. Photocatalysis has emerged as a promising strategy for such a C–C bond cleavage under ambient conditions, although the activity and selectivity need to be further improved. Herein, using polyimide as a photocatalyst, we report an efficient and selective C–C bond cleavage in a β-O-4 lignin model under visible light at room temperature. The lignin model was converted into aromatic products with >99% substrate conversion and >99% C–C bond cleavage selectivity, which are superior to previously reported photocatalytic systems. Experimental investigations together with theoretical calculations indicated that the superior performance of the polyimide photocatalyst was attributed to its strong photooxidation capability and efficient charge carrier separation efficiency. Mechanistic studies revealed that the dehydrogenation of the lignin model driven by photogenerated holes was the rate-determining step. This work provides useful guidance for the design of high-performance photocatalysts for selective C–C bond cleavage of lignin.

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