Cleavage∕cross-coupling strategy for converting β-O-4 linkage lignin model compounds into high valued benzyl amines via dual C–O bond cleavage

Eco-friendly regeneration of lignin with acidic deep eutectic solvent for adsorption of pollutant dyes for water cleanup

In this study, a simple and eco-friendly method was used to treat alkaline lignin with an acidic deep eutectic solvent (DES) to obtain regenerated lignin for the efficient adsorption of pollutant dyes from aqueous environment. Based on the yield and adsorption capacity of the sorbent for these dyes, conditions such as the type and concentration of DES component, solid-to-liquid ratio, reaction time, and temperature were optimized. By characterizing and comparing alkali lignin with regenerated lignin, a series of reactions were demonstrated to occur during the DES treatment process. The performance and mechanism of methylene blue and rhodamine B adsorption on regenerated lignin were studied systematically, and the maximum adsorbed amounts were 348.29 and 551.05 mg/g at 323 K, respectively. This study provides a new strategy for the green preparation of functionalized lignin and its use in the water pollutant treatment.

Hydrogen-transfer strategy in lignin refinery: Towards sustainable and versatile value-added biochemicals

Lignin, the most prevalent natural source of polyphenols on Earth, offers substantial possibilities for the conversion into aromatic compounds, which is critical for attaining sustainability and carbon neutrality. The hydrogen-transfer method has garnered significant interest owing to its environmental compatibility and economic viability. The efficacy of this approach is contingent upon the careful selection of catalytic and hydrogen-donating systems that decisively affect the yield and selectivity of the monomeric products resulting from lignin degradation. This paper highlights the hydrogen-transfer technique in lignin refinery, with a specific focus on the influence of hydrogen donors on the depolymerization pathways of lignin. It delineates the correlation between the structure and activity of catalytic hydrogen-transfer arrangements and the gamut of lignin-derived biochemicals, utilizing data from lignin model compounds, separated lignin, and lignocellulosic biomass. Additionally, the paper delves into the advantages and future directions of employing the hydrogen-transfer approach for lignin conversion. In essence, this concept investigation illuminates the efficacy of the hydrogen-transfer paradigm in lignin valorization, offering key insights and strategic directives to maximize lignin's value sustainably.

Advances in surface properties characterization and modification for lignin

Renewed interests on lignin and its derivatives have led to increasingly more investigations due to the problems in environmental impact while with the great reuse possibilities for producing them-based new and advanced materials to reduce the petroleum achieving sustainable development. The related studies have shown more integrated database on the surface properties characterization and modification of those renewable materials. Based on numerous works did at our group and others reported elsewhere, this review covers the surface properties of lignin and its derivatives in relation to various methods and theories. In this work, the progress on the recent developments of advanced methods for lignin surface characterization and modification are also documented. Of this review, a perspective is finally presented.

MOFs as Versatile Catalysts: Synthesis Strategies and Applications in Value-Added Compound Production

Catalysts played a crucial role in advancing modern human civilization, from ancient times to the industrial revolution. Due to high cost and limited availability of traditional catalysts, there is a need to develop cost-effective, high-activity, and nonprecious metal-based electrocatalysts. Metal-organic frameworks (MOFs) have emerged as an ideal candidate for heterogeneous catalysis due to their physicochemical properties, hybrid inorganic/organic structures, uncoordinated metal sites, and accessible organic sections. MOFs are high nanoporous crystalline materials that can be used as catalysts to facilitate polymerization reactions. Their chemical and structural diversity make them effective for various reactions compared to traditional catalysts. MOFs have been applied in gas storage and separation, ion-exchange, drug delivery, luminescence, sensing, nanofilters, water purification, and catalysis. The review focuses on MOF-enabled heterogeneous catalysis for value-added compound production, including alcohol oxidation, olefin oligomerization, and polymerization reactions. MOFs offer tunable porosity, high spatial density, and single-crystal XRD control over catalyst properties. In this review, MOFs were focused on reactions of CO2 fixation, CO2 reduction, and photoelectrochemical water splitting. Overall, MOFs have great potential as versatile catalysts for diverse applications in the future.

Multi-objective operation optimization of spent coffee ground torrefaction for carbon-neutral biochar production

Many energy-intensive processes are employed to enhance biomass fuel properties to overcome the difficulties in utilizing biomass as fuel. Therefore, energy conservation during these processes is crucial for realizing a circular bioeconomy. This study develops a newly devised method to evaluate SCG biochars' higher heating value (HHV) and predict moisture content from power consumption. It is found that the increasing rates of HHV immediately follow decreases in power consumption, which could be used to determine the pretreatment time for energy conservation. The non-dominated sorting genetic algorithm II (NSGA-II) maximizes SCG biochar's HHV while minimizing energy consumption. The results show that producing SCG biochar with 23.98 MJ∙kg^-1 HHV requires 20.042 MJ∙kg^-1, using a torrefaction temperature of 244 °C and torrefaction time of 27 min and 43 sec. Every kilogram of biochar with an energy yield of 85.93 % is estimated to cost NT$ 12.21.

Construction of Spirocyclic Pyrrolo[1,2-a]quinoxalines via Palladium-Catalyzed Hydrogenative Coupling of Phenols and Nitroarenes

The replacement of fossil resources with biomass resources in the construction of N-heterocycles is rapidly attracting research interest. Herein, we report palladium-catalyzed selective hydrogenative coupling of nitroarenes and phenols based on a transfer hydrogenation strategy, allowing straightforward access to spirocyclic pyrrolo- and indolo-fused quinoxalines, a class of compounds found in numerous natural alkaloids. The synthetic protocol is characterized by a broad substrate scope and the utilization of biomass-derived reactants and commercially available catalysts. In such transformations, high-pressure and explosive hydrogen are not required. This report provides a new protocol for converting biomass-derived phenols into value-added nitrogen-containing chemicals.