Expanding the Boundary of Biorefinery: Organonitrogen Chemicals from Biomass

Heterojunction-enhanced electron transfer of copper nanoparticles promotes electrocatalytic ammonia synthesis from nitric oxide

Electrocatalytic nitric oxide (NO) reduction to ammonia (NH3) serves as an innovative approach that concurrently addresses two pressing challenges: sustainable NH3 synthesis through renewable pathways and environmental detoxification of hazardous nitric oxide. While the thermodynamic driving force of the electrocatalytic NO-to-NH3 conversion (NORR) favors NH3 generation, the system's practical viability is compromised by kinetically sluggish reaction pathways and the inherent solubility constraints of NO (1.93 mM in aqueous media at 25 ℃), with performance attenuation becoming progressively severe when the NO concentration decreases. However, an efficient copper-based catalyst that can effectively adsorb and activate NO is not yet available. Here, we have utilized the strategy of biphasic carriers to enhance MSI (metal-support interactions) to develop rutile-anatase titanium dioxide (TiO2) heterojunction-supported copper nanoparticles (Cu@AR-TiO2) as an effective catalyst for NORR. Under processing conditions of 10 % v/v NO, the NH3-Faraday efficiency reached 91.38 % at -0.7 V vs. RHE, with the NH3 yield rate achieving 393.73 μmol h-1 mg-1cat at -0.8 V vs. RHE, surpassing counterparts devoid of heterojunction or copper nanoparticles. X-ray photoelectron spectroscopy and X-ray absorption spectroscopy shows that the three-phase interface formed by rutile-anatase TiO2 (AR-TiO2) heterojunction with copper nanoparticles (Cu NPs) enhanced the MSI of Cu NPs with the carrier to effectively promote the electron transfer from Cu NPs to carriers to form electron-deficient copper. In-situ Raman coupled with NO temperature-programmed desorption experiments revealed that the distinctive electron structure of Cu@AR-TiO2 (copper nanoparticles supported by AR-TiO2) strengthened the adsorption of NO and facilitated the generation of·NH3 (ammonia being absorbed) intermediate, ultimately achieving superior catalytic efficiency in NH3 production. This provides a novel approach to the design of NO-to-NH3 catalysts.

Copper-catalyzed C-C bond cleavage coupling with CN bond formation toward mild synthesis of lignin-based benzonitriles

N-participated lignin depolymerization is of great importance for the transformation of waste lignin into value-added chemicals. The vast majority of developed strategies employ organic amines as nitrogen source, and considerable methods rely on excessive use of strong base, which suffers severe environmental issues. Herein, benzonitrile derivatives are synthesized from oxidized lignin β-O-4 model compounds in the presence of solid nitrogen source (NH4)2CO3 under mild, base-free conditions over commercially available copper catalyst. Mechanism studies suggest the transformation undergoes a one-pot, highly coupled cascade reaction path involving oxidative C-C bond cleavage and in-situ formation of CN bond. Of which, Cu(OAc)2 catalyzes the transfer of hydrogen from Cβ (Cβ-H) to Cα, leading to the cleavage of Cα-Cβ bonds to offer benzaldehyde derivative, this intermediate then reacts in-situ with (NH4)2CO3 to afford the targeted aromatic nitrile product. Tetrabutylammonium iodide (TBAI), acting as a promoter, plays a key role in breaking the Cα-Cβ bonds to form the intermediate benzaldehyde derivative. With this protocol, the feasibility of the production of value-added syringonitrile from birchwood lignin has been demonstrated. This transformation provides a sustainable approach to benzonitrile chemicals from renewable source of lignin.

Low pressure amide hydrogenation enabled by magnetocatalysis

The catalytic hydrogenation of amides with molecular hydrogen (H2) is an appealing route for the synthesis of valuable amines entering in the preparation of countless organic compounds. Running effective amide hydrogenation under mild H2 pressures is challenging although desirable to preclude the need for specialized high-pressure technologies in research and industry. Here we show that magnetocatalysis with standard supported catalysts enables unprecedented amide hydrogenation at mild conditions. Widely available and commercial platinum on alumina (Pt/Al2O3) was functionalized with iron carbide nanoparticles (ICNPs) to allow for localized and rapid magnetic induction heating resulting in the activation of neighboring Pt sites by thermal energy transfer. Exposure of the ICNPs@Pt/Al2O3 catalyst to an alternating current magnetic field enables highly active and selective hydrogenation of a range of amides at a reactor temperature of 150 °C under 3 bar or even ambient pressure of H2. ICNPs@Pt/Al2O3 reacts adaptively to fluctuations in electricity supply mimicking the use of intermittent renewable energy sources. This work may pave the way toward a greatly enhanced practicability of amide hydrogenation at the laboratory and production scales, and demonstrates more generally the broad potential of the emerging field of magnetocatalysis for synthetic chemistry.

Photocatalytic upcycling of polylactic acid to alanine by sulfur vacancy-rich cadmium sulfide

Photocatalytic conversion has emerged as a promising strategy for harnessing renewable solar energy in the valorization of plastic waste. However, research on the photocatalytic transformation of plastics into valuable nitrogen-containing chemicals remains limited. In this study, we present a visible-light-driven pathway for the conversion of polylactic acid (PLA) into alanine under mild conditions. This process is catalyzed by defect-engineered CdS nanocrystals synthesized at room temperature. We observe a distinctive volcano-shaped relationship between sulfur vacancy content in CdS and the corresponding alanine production rate reaching up to 4.95 mmol/g catalyst/h at 70 oC. Ultraviolet-visible, photocurrent, electrochemical impedance, transient absorption, photoluminescence, and Fourier-transform infrared spectroscopy collectively highlight the crucial role of sulfur vacancies. The surface vacancies serve as adsorption sites for lactic acid; however, an excessive number of vacancies can hinder charge transfer efficiency. Sulfur vacancy-rich CdS exhibits high stability with maintained performance and morphology over several runs, effectively converts real-life PLA products and shows potential in the amination of other polyesters. This work not only highlights a facile approach for fabricating defect-engineered catalysts but also presents a sustainable method for upcycling plastic waste into valuable chemicals.

Catalytic conversion of chitin biomass into key platform chemicals

Chitin is the most abundant nitrogen-containing biomass on Earth and presents a compelling alternative to fossil fuels for chemical production. The catalytic conversion of chitin offers a viable approach for harnessing its inherent carbon and nitrogen contents, contributing to developing a green and sustainable society. This feature article reviews recent advances in shell waste biorefinery, with an emphasis on the contributions from our group. Efficient and sustainable chitin extraction methods are highlighted, along with the conversion of chitin biomass (N-acetyl-D-glucosamine (NAG), D-glucosamine, chitosan, and chitin) into key platform chemicals, mainly including furans, amino/amide sugars, organic acids and amino/amide acids. Catalytic strategies and production pathways are detailed, and current challenges and future research directions in chitin valorization are discussed.

Chemical looping synthesis of amines from N2 via iron nitride as a mediator

Amines are commonly synthesized through the amination of organooxygenates using ammonia, frequently involving the use of noble metal catalysts. In this study, we present an alternative route to make amines using iron nitride (Fe2.5N) as the nitrogen source. Without any additional catalyst, Fe2.5N reacts with a range of alcohols at 250 °C under 1 or 10 bar H2 to produce amines as major products. Mechanistic investigations indicate that hydrogen activates the nitrogen species within iron nitride, converting them into surface NH and NH2 groups that then react with alcohols to form amines. Building on this foundation, we further demonstrate an iron nitride-mediated chemical looping pathway that utilizes N2 as the nitrogen source to synthesize octylamines. In this process, N2 first reacts with iron to form FexN by a ball-milling method at ambient temperature and 6 bar N2. The as-prepared FexN subsequently reacts with alcohols to yield amines, transferring over 80% of the nitrogen to organic compounds. This looping process proves stable across four cycles.

Exploration of small-molecule inhibitors targeting Hsp110 as novel therapeutics

The heat shock protein (HSP) 110 family has a key role as a unique class of molecular chaperones maintaining cellular proteostasis in eukaryotes. Abnormal activation of Hsp110 has been implicated in several diseases. Given its important role in pathogenesis, Hsp110 has become a novel drug target for disease diagnosis and targeted therapy. Thus, targeting Hsp110 or its interactions with client proteins offers new therapeutic approaches. Recent studies of small-molecule inhibitors that target Hsp110 in vitro and in vivo have yielded encouraging results. In this review, we provide an overview of novel therapeutics targeting Hsp110, mainly inhibitors of protein-protein interactions (PPIs), together with a brief discussion of the relevant challenges, opportunities, and future directions.

Sustainable ammonia and amines from chitin

Efforts are underway to explore alternative methods to the Haber-Bosch process for sustainable ammonia production, while the potential for ammonia extraction from natural nitrogenous biomass is under-exploited. Here, a synergistic catalytic strategy involving acid and modified Ru-based catalysts is communicated for the direct production of amines and ammonia from chitin. Phosphoric acid promotes the cleavage of ether bonds in biomass polymers and also serves to protect amino groups from being removed. Selective hydrogenation, deoxygenation, and amination can be achieved by controllably adjusting the ratio of Ru0/Run+. The utilization of nitrogen atoms in chitin can reach up to 95 % (21 % amines, 74 % ammonium), and the catalytic process is applicable to waste shrimp shells. This study demonstrates the possibility of efficient production of nitrogen-containing compounds from abundant biopolymers.

Alkaline Modified Mesoporous Silica Supported Ruthenium Catalyst for Improved α-Amino Acid Synthesis

Amino acids are a class of compounds with wide-ranging applications. The synthesis of amino acids from biomass-derived α-keto acids and ammonia is a sustainable way but the unstable primary imine intermediates (R-C=NH) easily form oligomers. Herein, targeting this problem, alkaline modified mesoporous silica was employed as a support for ruthenium (Ru/M-MCM-41), which could be used as a bifunctional catalyst in the reductive amination of α-keto acids to synthesize α-amino acids. The incorporation of Sr improved the dispersion of Ru nanoparticles and enhanced metal-support interactions via electron transfer from Sr to Ru, and the active Ru sites could efficiently hydrogenate primary imine intermediates to α-amino acids, thus prohibiting the formation of oligomers. Moreover, the Sr-dopant introduces base sites that could catalyze the hydrolysis of oligomers back to primary imine intermediates and finally hydrogenated to α-amino acids. As a result, >99 % yield of glycine was achieved from glyoxylic acid over Ru/Sr-MCM-41, which is nearly three times that achieved over Ru/MCM-41 (32.2 %).

Dissolving Chitin by Novel Deep Eutectic Solvents for Effectively Enzymatic Hydrolysis

Chitin is the most productive nitrogen-containing polysaccharide in nature with immense potential for transforming into a range of chemicals. However, its dense crystal structure poses a challenge for depolymerization, limiting its applications. To overcome these challenges, a novel series of deep eutectic solvents (DESs) based on benzyltrimethylammonium chloride (TMBAC) as the hydrogen bond acceptor was developed. These TMBAC-based DESs, in combination with lactic acid, oxalic acid, and malic acid as the hydrogen bond donor demonstrated efficient chitin dissolution, achieving a solubility of up to 12% and an 88% recovery rate of regenerated chitin. The regenerated chitin was characterized using XRD, FT-IR, SEM, and 13C CP-MAS NMR, which indicated the preservation of chitin's chemical structure, a significant decrease in crystallinity, and a reduction in the molecular weight. Furthermore, the enzymatic hydrolysis efficiency of chitin was nearly doubled after treatment with TMBAC-based DESs, surpassing the effectiveness of untreated chitin. This approach holds promise for facilitating subsequent transformation and utilization of chitin.

Chemicals and fuels from lipid-containing biomass: A comprehensive exploration

In response to address the climate crisis, there has been a growing focus on substituting conventional refinery-derived products with those derived from biorefineries. The utilization of lipids as primary materials or intermediates for the synthesis of chemicals and fuels, which are integral to the existing chemical and petrochemical industries, is a key step in this transition. This review provides a comprehensive overview of the production of sustainable chemicals (acids and alcohols), biopolymers, and fuels (including gasoline, kerosene, biodiesel, and heavy fuel oil) from lipids derived from terrestrial and algal biomass. The production of chemicals from lipids involves diverse methods, including polymerization, epoxidation, and separation/purification. Additionally, the transformation of lipids into biofuels can be achieved through processes such as catalytic cracking, hydroprocessing, and transesterification. This review also suggests future research directions that further advance the lipid valorization processes, including enhancement of catalyst durability at harsh conditions, development of deoxygenation process with low H2 consumption, investigation of precise separation of target compounds, increase in lipid accumulation in algal biomass, and development of methods that utilize residues and byproducts generated during lipid extraction and conversion.

Single-Atom Co-N4 Sites Mediate C=N Formation via Reductive Coupling of Nitroarenes with Alcohols

It remains challenging to construct C=N bonds due to their facile hydrogenation. Herein, a single Co atom catalyst was discovered to be active for the selective construction of C=N bonds toward the synthesis of imines and N-heterocycles via reductive coupling of nitroarenes with various alcohols, including inert aliphatic ones. DFT calculations and experimental data revealed that the transfer hydrogenation proceeded via the intramolecular hydride transfer and the transfer of H from the α-Csp3-H bond to the nitro group was the rate-determining step. The single Co atoms served as a bridge to transfer the electrons from the catalyst to the adsorbed alcohol molecules, resulting in the activation of the α-Csp3-H bond. Unlike metal nanoparticles, the C=N bonds in imine products can be reserved due to the large steric hindrance from substituents on C and N. DFT calculation also confirmed that transfer hydrogenation of the C=N bonds in imines is thermodynamically unfavored with a much higher energy barrier compared with the transfer hydrogenation of the -NO2 group (1.47 vs 1.15 eV).

Porous carbon/Fe3O4 nanocomposite as a new magnetically recoverable catalyst for the preparation of polyhydroquinolines

A porous carbon/Fe3O4 nanocomposite (PC/Fe3O4 nanocomposite) was prepared through the pyrolysis of peanut shells as biowaste with ferrous ferric oxide to give a new magnetically recoverable catalyst. In the designed nanocomposite, magnetic iron oxide nanoparticles are properly distributed on the surface and cavities of porous carbon obtained from biomass. Increasing the active surface and magnetic recovery capability results in catalytic synergy, thereby promoting the reaction with an appropriate catalytic effect. The catalytic ability of the porous carbon/Fe3O4 nanocomposite as a nanomagnetically recoverable catalyst was successfully tested for the synthesis of polyhydroquinolines.

Electrocatalytic Upgrading of Plastic and Biomass-Derived Polyols to Formamide under Ambient Conditions

Electrocatalytic upgrading of wasted plastic and renewable biomass represents a sustainable method to produce chemicals but is limited to carbohydrates, leaving other value-added chemicals, such as organonitrogen compounds, being scarcely explored. Herein, we reported an electrocatalytic oxidation strategy to transform polyethylene terephthalate (PET) plastic-derived ethylene glycol (EG) and biomass-derived polyols into formamide, in the presence of ammonia (NH3) over a tungsten oxide (WO3) catalyst. Taking EG-to-formamide as an example, we achieved a high formamide productivity of 537.7 μmol cm-2 h-1 with FE of 43.2 % at a constant current of 100 mA cm-2 in a flow electrolyzer with 12-h test, representing a more advantageous performance compared with previous reports for formamide electrosynthesis. Mechanistic understanding revealed that the cleavage of the C-C bond in the EG was facilitated by nucleophilic attack of in situ formed nitrogen radicals from NH3, with resultant C-N bond construction and eventually formamide production. Furthermore, this strategy can be extended to transformation of PET bottle and a series of biomass-derived polyols with carbon number from three (glycerol) to six (glucose), producing formamide with high efficiencies. This work demonstrates a sustainable upgrading strategy of plastic and biomass that may have implications to more value-added chemicals production beyond carbohydrates.

Valorization of Agriculture Residues into Value-Added Products: A Comprehensive Review of Recent Studies

Global agricultural by-products usually go to waste, especially in developing countries where agricultural products are usually exported as raw products. Such waste streams, once converted to "value-added" products could be an additional source of revenue while simultaneously having positive impacts on the socio-economic well-being of local people. We highlight the utilization of thermochemical techniques to activate and convert agricultural waste streams such as rice and straw husk, coconut fiber, coffee wastes, and okara power wastes commonly found in the world into porous activated carbons and biofuels. Such activated carbons are suitable for various applications in environmental remediation, climate mitigation, energy storage, and conversions such as batteries and supercapacitors, in improving crop productivity and producing useful biofuels.

Hybrid homogeneous/heterogeneous relay catalysis for efficient synthesis of 5-aminomethyl-2-furancarboxylic acid from HMF

Here we present a hybrid catalytic pathway for efficient synthesis of 5-aminomethyl-2-furancarboxylic acid (AMFC), a bio-based nylon-6 analogue monomer, from 5-hydroxymethylfurfural (HMF). This method combines homogeneous-catalyzed selective oxidation of HMF to 5-formyl-2-furancarboxylic acid (FFCA) with heterogeneous-catalyzed reductive amination using ammonia as the nitrogen source. Through this relay strategy, we achieve significant enhancements in overall efficiency, resulting in isolation yields of up to 92% for highly selective and scalable AMFC production from HMF.

Catalytic conversion of chitin-based biomass to nitrogen-containing chemicals

The exploration of renewable alternatives to fossil fuels for chemical production is indispensable to achieve the ultimate goals of sustainable development. Chitin biomass is an abundant platform feedstock that naturally bears both nitrogen and carbon atoms to produce nitrogen-containing chemicals (including organonitrogen ones and inorganic ammonia). The expansion of biobased chemicals toward nitrogen-containing ones can elevate the economic competitiveness and benefit the biorefinery scheme. This review aims to provide an up-to-date summary on the overall advances of the chitin biorefinery for nitrogen-containing chemical production, with an emphasis on the design of the catalytic systems. Catalyst design, solvent selection, parametric effect, and reaction mechanisms have been scrutinized for different transformation strategies. Future prospectives on chitin biorefinery have also been outlined.

Eco-friendly and safe alternatives for the valorization of shrimp farming waste

The seafood industry generates waste, including shells, bones, intestines, and wastewater. The discards are nutrient-rich, containing varying concentrations of carotenoids, proteins, chitin, and other minerals. Thus, it is imperative to subject seafood waste, including shrimp waste (SW), to secondary processing and valorization for demineralization and deproteination to retrieve industrially essential compounds. Although several chemical processes are available for SW processing, most of them are inherently ecotoxic. Bioconversion of SW is cost-effective, ecofriendly, and safe. Microbial fermentation and the action of exogenous enzymes are among the significant SW bioconversion processes that transform seafood waste into valuable products. SW is a potential raw material for agrochemicals, microbial culture media, adsorbents, therapeutics, nutraceuticals, and bio-nanomaterials. This review comprehensively elucidates the valorization approaches of SW, addressing the drawbacks of chemically mediated methods for SW treatments. It is a broad overview of the applications associated with nutrient-rich SW, besides highlighting the role of major shrimp-producing countries in exploring SW to achieve safe, ecofriendly, and efficient bio-products.

Nitrogenous Intermediates in NOx-involved Electrocatalytic Reactions

Chemical manufacturing utilizing renewable sources and energy emerges as a promising path towards sustainability and carbon neutrality. The electrocatalytic reactions involving nitrogen oxides (NOx) offered a potential strategy for synthesizing various nitrogenous chemicals. However, it is currently hindered by low selectivity/efficiency and limited reaction pathways, mainly due to the difficulties in controllable generation and utilization of nitrogenous intermediates. In this minireview, focusing on nitrogenous intermediates in NOx-involved electrocatalytic reactions, we discuss newly developed methodologies for studying and controlling the generation, conversion, and utilizing of nitrogenous intermediates, which enable recent developments in NOx-involved electrocatalytic reactions that yield various products, including ammonia (NH3), organonitrogen molecules, and nitrogenous compounds exhibiting unconventional oxidation states. Furthermore, we also make an outlook to highlight future directions in the emerging field of NOx-involved electrocatalytic reactions.

The contemporary nexus of medicines security and bioprospecting: a future perspective for prioritizing the patient

Reacting to the challenges presented by the evolving nexus of environmental change, defossilization, and diversified natural product bioprospecting is vitally important for advancing global healthcare and placing patient benefit as the most important consideration. This overview emphasizes the importance of natural and synthetic medicines security and proposes areas for global research action to enhance the quality, safety, and effectiveness of sustainable natural medicines. Following a discussion of some contemporary factors influencing natural products, a rethinking of the paradigms in natural products research is presented in the interwoven contexts of the Fourth and Fifth Industrial Revolutions and based on the optimization of the valuable assets of Earth. Following COP28, bioprospecting is necessary to seek new classes of bioactive metabolites and enzymes for chemoenzymatic synthesis. Focus is placed on those performance and practice modifications which, in a sustainable manner, establish the patient, and the maintenance of their prophylactic and treatment needs, as the priority. Forty initiatives for natural products in healthcare are offered for the patient and the practitioner promoting global action to address issues of sustainability, environmental change, defossilization, quality control, product consistency, and neglected diseases to assure that quality natural medicinal agents will be accessible for future generations.

Aqueous amine enables sustainable monosaccharide, monophenol, and pyridine base coproduction in lignocellulosic biorefineries

Thought-out utilization of entire lignocellulose is of great importance to achieving sustainable and cost-effective biorefineries. However, there is a trade-off between efficient carbohydrate utilization and lignin-to-chemical conversion yield. Here, we fractionate corn stover into a carbohydrate fraction with high enzymatic digestibility and reactive lignin with satisfactory catalytic depolymerization activity using a mild high-solid process with aqueous diethylamine (DEA). During the fractionation, in situ amination of lignin achieves extensive delignification, effective lignin stabilization, and dramatically reduced nonproductive adsorption of cellulase on the substrate. Furthermore, by designing a tandem fractionation-hydrogenolysis strategy, the dissolved lignin is depolymerized and aminated simultaneously to co-produce monophenolics and pyridine bases. The process represents the viable scheme of transforming real lignin into pyridine bases in high yield, resulting from the reactions between cleaved lignin side chains and amines. This work opens a promising approach to the efficient valorization of lignocellulose.

Clean Synthetic Strategies to Biologically Active Molecules from Lignin: A Green Path to Drug Discovery

Deriving active pharmaceutical agents from renewable resources is crucial to increasing the economic feasibility of modern biorefineries and promises to alleviate critical supply-chain dependencies in pharma manufacturing. Our multidisciplinary approach combines research in lignin-first biorefining, sustainable catalysis, and alternative solvents with bioactivity screening, an in vivo efficacy study, and a structural-similarity search. The resulting sustainable path to novel anti-infective, anti-inflammatory, and anticancer molecules enabled the rapid identification of frontrunners for key therapeutic indications, including an anti-infective against the priority pathogen Streptococcus pneumoniae with efficacy in vivo and promising plasma and metabolic stability. Our catalytic methods provided straightforward access, inspired by the innate structural features of lignin, to synthetically challenging biologically active molecules with the core structure of dopamine, namely, tetrahydroisoquinolines, quinazolinones, 3-arylindoles and the natural product tetrahydropapaveroline. Our diverse array of atom-economic transformations produces only harmless side products and uses benign reaction media, such as tunable deep eutectic solvents for modulating reactivity in challenging cyclization steps.

Electrocatalytic Systems for NOx Valorization in Organonitrogen Synthesis

Inorganic nitrogen oxide (NOx ) species, such as NO, NO2 , NO3 - , NO2 - generated from the decomposition of organic matters, volcanic eruptions and lightning activated nitrogen, play important roles in the nitrogen cycle system and exploring the origin of life. Meanwhile, excessive emission of NOx gases and residues from industry and transportation causes troubling problems to the environment and human health. How to efficiently handle these wastes is a global problem. In response to the growing demand for sustainability, scientists are actively pursuing sustainable electrochemical technologies powered by renewable energy sources and efficient utilization of hydrogen energy to convert NOx species into high-value organonitrogen chemicals. In this minireview, recent advances of electrocatalytic systems for NOx species valorization in organonitrogen synthesis are classified and described, such as amino acids, amide, urea, oximes, nitrile etc., that have been widely applied in medicine, life science and agriculture. Additionally, the current challenges including multiple side reactions and complicated paths, viable solutions along with future directions ahead in this field are also proposed. The coupling electrocatalytic systems provide a green mode for fixing nitrogen cycle bacteria and bring enlightenment to human sustainable development.

Reductive Amination of Levulinic Acid to Pyrrolidones: Key Step in Biomass Valorization towards Nitrogen-Containing Chemicals

Nowadays, the field of biomass conversion is gradually moving towards an encouraging stage. The preparation of nitrogen-containing chemicals using various biomass resources instead of fossil resources do not only reduce carbon emissions, but also diversify the products of biomass conversion, thus increasing the economic competitiveness of biomass refining systems. Levulinic acid (LA) can be used as a promising intermediate in biomass conversion for further synthesis of pyrrolidone via reductive amination. However, there are still many critical issues to be solved. Particularly, the specific effects of catalysts on the performance of LA reductive amination have not been sufficiently revealed, and the potential impacts of key conditional factors have not been clearly elucidated. In view of this, this review attempts to provide theoretical insights through an in-depth interpretation of the above key issues. The contribution of catalysts to the reductive amination of LA as well as the catalyst structural preferences for improving catalytic performance are discussed. In addition, the role of key conditional factors is discussed. The insights presented in this review will contribute to the design of catalyst nanostructures and the rational configuration of green reaction conditions, which may provide inspiration to facilitate the nitrogen-related transformation of more biomass platform molecules.

Nitrogen activation and surface charge regulation for enhancing the visible-light-driven N2 fixation over MoS2/UiO-66(SH)2

A series of dehydrated MoS2/UiO-66(SH)2 (MS/UiS) composites has been prepared as photocatalysts for N2 fixation. Typically, 10% MS/UiS exhibits the best performance with an NH4+ yield rate of 54.08 μmol∙g-1∙h-1. 15N isotope test confirmed that the sample 10% MS/UiS was most effective for reducing N2 to ammonia. Such enhanced activity was due to the presence of abundant unsaturated Zr and Mo sites which would synergistically promote the adsorption and activation of N2. The photogenerated electrons would transfer to the unsaturated Zr-O clusters while part of photogenerated electrons at the interface migrate to MS via MoVI-O interactions between MS and UiS. These two electron transfer pathways effectively promote the separation of photogenerated carriers. The activated N2 is reduced to ammonia by the synergistic effect of protonated hydrogen and photogenerated electrons. Finally, a possible N2 fixation mechanism is proposed which emphasizes the significant roles of nitrogen activation and interface interaction in composites photocatalyst for improving photocatalytic performance.

The effects of race and probiotic supplementation on the intestinal microbiota of 10-km open-water swimmers

This study collected the stools of 10-km open-water swimmers after race and probiotic supplementation, and 16S rRNA sequencing and metabolomic analysis were performed to clarify their intestinal microbiota characteristics. The findings revealed a relatively high proportion of Firmicutes in all the athletes. Firmicutes in female athletes were significantly higher after probiotic supplementation. The intestinal microbiota of athletes was closely associated with the pathways of exercise against cancer, exercise against aging, exercise for improving cognition, sphingolipid metabolism and endocrine resistance. Future research should focus on the relationship between Firmicutes and Proteobacteria with super class metabolites in athletes. This report initially explored the changes in intestinal microbiota involved in metabolic pathways in athletes after race and after probiotic supplementation and provided a theoretical basis for the further improvement of the monitoring of their physical function after race and selection of nutritional strategies during exercise training.

Integration of plasma and electrocatalysis to synthesize cyclohexanone oxime under ambient conditions using air as a nitrogen source

Direct fixation of N2 to N-containing value-added chemicals is a promising pathway for sustainable chemical manufacturing. There is extensive demand for cyclohexanone oxime because it is the essential feedstock of Nylon 6. Currently, cyclohexanone oxime is synthesized under harsh conditions that consume a considerable amount of energy. Herein, we report a novel approach to synthesize cyclohexanone oxime by in situ NO3- generation from air under ambient conditions. This process was carried out through an integrated strategy including plasma-assisted air-to-NOx and co-electrolysis of NOx and cyclohexanone. A high rate of cyclohexanone oxime formation at 20.1 mg h-1 cm-2 and a corresponding faradaic efficiency (FE) of 51.4% was achieved over a Cu/TiO2 catalyst, and the selectivity of cyclohexanone oxime was >99.9% on the basis of cyclohexanone. The C-N bond formation mechanism was examined by in situ experiments and theoretical calculations, which showed that cyclohexanone oxime forms through the reaction between an NH2OH intermediate and cyclohexanone.

Synthesis of piperidines and pyridine from furfural over a surface single-atom alloy Ru1CoNP catalyst

The sustainable production of value-added N-heterocycles from available biomass allows to reduce the reliance on fossil resources and creates possibilities for economically and ecologically improved synthesis of fine and bulk chemicals. Herein, we present a unique Ru1CoNP/HAP surface single-atom alloy (SSAA) catalyst, which enables a new type of transformation from the bio-based platform chemical furfural to give N-heterocyclic piperidine. In the presence of NH3 and H2, the desired product is formed under mild conditions with a yield up to 93%. Kinetic studies show that the formation of piperidine proceeds via a series of reaction steps. Initially, in this cascade process, furfural amination to furfurylamine takes place, followed by hydrogenation to tetrahydrofurfurylamine (THFAM) and then ring rearrangement to piperidine. DFT calculations suggest that the Ru1CoNP SSAA structure facilitates the direct ring opening of THFAM resulting in 5-amino-1-pentanol which is quickly converted to piperidine. The value of the presented catalytic strategy is highlighted by the synthesis of an actual drug, alkylated piperidines, and pyridine.

Tuning the Acid-Base Properties of Lignin-Derived Carbon Modulated ZnZr/SiO2 Catalysts for Selective and Efficient Production of Butadiene from Ethanol

The direct selective conversion of ethanol to butadiene (ETB) is a competitive and environmentally friendly process compared to the traditional crude cracking route. The acid-base properties of catalysts are crucial for the direct ETB process. Herein, we report a rationally designed multifunctional lignin-derived carbon-modulated ZnZr/SiO2 (L-ZnZr/SiO2) catalyst with suitable acid-base properties for the direct ETB reaction. A variety of characterization techniques are employed to investigate the relationship between the acid-base properties and catalytic performance of the multifunctional lignin-modulated ZnZr/SiO2 catalysts. The results revealed that the rationally additional lignin-modulated carbon enhances both the acidity and basicity of the ZnZr/SiO2 catalysts, providing a suitable acid-base ratio that boosts the direct ETB reactivity. Meanwhile, the 1% L-ZnZr/SiO2 catalyst possessed ethanol conversion and butadiene selectivity as high as 98.4% and 55.5%, respectively, and exhibited excellent catalytic stability.

Microwave-Assisted One Pot Cascade Conversion of Furfural to γ-Valerolactone over Sc(OTf)3

γ-Valerolactone (GVL) is considered as a star biochemical which can be used as a green solvent, fuel additive and versatile organic intermediate. In this study, metal triflate (M(OTf)n ) was utilized as the catalyst for one-pot transformation of furfural (FF) to GVL in alcohol media under microwave irradiation. Alcohol plays multiple functions including solvent, hydrogen donor and alcoholysis reagent in this cascade reaction process. And process efficiency of GVL production from FF upgrading is strongly related to the effective charge density of selected catalyst and the reduction potential of selected alcohol. Complex (OTf)n -M-O(H)R, presenting both Brønsted acid and Lewis acid, is the real catalytic active species in this cascade reaction process. Among various catalysts, Sc(OTf)3 exhibited the best catalytic activity for GVL production. Various reaction parameters including the Sc(OTf)3 amount, reaction temperature and time were optimized by the response surface methodology with the central composite design (RSM-CCD). Up to 81.2 % GVL yield and 100 % FF conversion were achieved at 143.9 °C after 8.1 h in the presence of 0.16 mmol catalyst. This catalyst exhibits high reusability and can be regenerated by oxidative degradation of humins. In addition, a plausible cascade reaction network was proposed based on the distribution of product.

Electrochemical Wastewater Refining: A Vision for Circular Chemical Manufacturing

Wastewater is an underleveraged resource; it contains pollutants that can be transformed into valuable high-purity products. Innovations in chemistry and chemical engineering will play critical roles in valorizing wastewater to remediate environmental pollution, provide equitable access to chemical resources and services, and secure critical materials from diminishing feedstock availability. This perspective envisions electrochemical wastewater refining─the use of electrochemical processes to tune and recover specific products from wastewaters─as the necessary framework to accelerate wastewater-based electrochemistry to widespread practice. We define and prescribe a use-informed approach that simultaneously serves specific wastewater-pollutant-product triads and uncovers a mechanistic understanding generalizable to broad use cases. We use this approach to evaluate research needs in specific case studies of electrocatalysis, stoichiometric electrochemical conversions, and electrochemical separations. Finally, we provide rationale and guidance for intentionally expanding the electrochemical wastewater refining product portfolio. Wastewater refining will require a coordinated effort from multiple expertise areas to meet the urgent need of extracting maximal value from complex, variable, diverse, and abundant wastewater resources.

One-Pot Chitin Conversion to High-Activity Antifungal N,N-Dimethyl Chitosan Oligosaccharides

Chitosan oligosaccharide and its derivatives are known for their diverse biological activities. In this study, we communicate a convenient one-pot synthesis of N,N-dimethyl chitosan oligosaccharide (DMCOS) from chitin via acid-catalyzed tandem depolymerization-deacetylation-N-methylation pathway using formaldehyde as the methylation reagent. The synthesis protocol offers 77 % DMCOS that features a high degree of deacetylation, a high degree of methylation, and a low average molecular weight. Compared to chitosan, DMCOS exhibits superior antifungal activity against Candida species. Mechanism study reveals a previously non-reported hydroxyl group-assisted effect that facilitates the reductive amination reaction under strong acidic conditions. Overall, our findings demonstrate the feasibility of direct synthesis of DMCOS from chitin, highlighting its potential use in anti-fungal applications.

Recent advances in catalytic synthesis of 2,5-furandimethanol from 5-hydroxymethylfurfural and carbohydrates

5-Hydroxymethylfurfural (HMF) is a versatile platform chemical derived from the dehydration of renewable carbohydrates (typically glucose/fructose-based monosaccharides, oligosaccharides, and polysaccharides). Some useful compounds, such as 2,5-furandimethanol (FDM), 2,5-dimethylfuran (DMF) and 2,5-dimethyltetrahydrofuran (DMTHF), have been synthesized by reduction of HMF. Among these, FDM is a promising diol and can be further converted towards fine chemicals, liquid fuels and polymer materials. In this review, some typical catalytic systems for the synthesis of FDM from both HMF and carbohydrates were summarized. The discussion focused on controlling the reaction networks for the reduction of HMF. The reaction mechanisms and the stability of the catalysts were introduced briefly. Last but not least, the prospects of effective production of FDM were discussed as well.

Design of Bifunctional Nanocatalysts Based on Zeolites for Biomass Processing

Bifunctional catalysts consisting of metal-containing nanoparticles (NPs) and zeolite supports have received considerable attention due to their excellent catalytic properties in numerous reactions, including direct (biomass is a substrate) and indirect (platform chemical is a substrate) biomass processing. In this short review, we discuss major approaches to the preparation of NPs in zeolites, concentrating on methods that allow for the best interplay (synergy) between metal and acid sites, which is normally achieved for small NPs well-distributed through zeolite. We focus on the modification of zeolites to provide structural integrity and controlled acidity, which can be accomplished by the incorporation of certain metal ions or elements. The other modification avenue is the adjustment of zeolite morphology, including the creation of numerous defects for the NP entrapment and designed hierarchical porosity for improved mass transfer. In this review, we also provide examples of synergy between metal and acid sites and emphasize that without density functional theory calculations, many assumptions about the interactions between active sites remain unvalidated. Finally, we describe the most interesting examples of direct and indirect biomass (waste) processing for the last five years.

Switchable product selectivity in dehydration of N-acetyl-d-glucosamine promoted by choline chloride-based deep eutectic solvents

Herein, we report choline chloride-based deep eutectic solvents (DESs) promoted conversion of N-acetyl-d-glucosamine (GlcNAc) into nitrogen-containing compounds, i.e., 3-acetamido-5-(1',2'-dihydroxyethyl) furan (Chromogen III) and 3-acetamido-5-acetylfuran (3A5AF). The binary deep eutectic solvent choline chloride-glycerin (ChCl-Gly), was found to promote the dehydration of GlcNAc to form Chromogen III, which reaches a maximum yield of 31.1%. On the other hand, the ternary deep eutectic solvent, choline chloride-glycerol-B(OH)3 (ChCl-Gly-B(OH)3), promoted the further dehydration of GlcNAc into 3A5AF with a maximum yield of 39.2%. In addition, the reaction intermediate, 2-acetamido-2,3-dideoxy-d-erythro-hex-2-enofuranose (Chromogen I), was detected by in situ nuclear magnetic resonance (NMR) techniques when promoted by ChCl-Gly-B(OH)3. The experimental results of the 1H NMR chemical shift titration showed ChCl-Gly interactions with α-OH-3 and α-OH-4 of GlcNAc, which is responsible for promoting the dehydration reaction. Meanwhile, the strong interaction between Cl- and GlcNAc was demonstrated by 35Cl NMR.

The Loss of Structural Integrity of 3D Chitin Scaffolds from Aplysina aerophoba Marine Demosponge after Treatment with LiOH

Aminopolysaccharide chitin is one of the main structural biopolymers in sponges that is responsible for the mechanical stability of their unique 3D-structured microfibrous and porous skeletons. Chitin in representatives of exclusively marine Verongiida demosponges exists in the form of biocomposite-based scaffolds chemically bounded with biominerals, lipids, proteins, and bromotyrosines. Treatment with alkalis remains one of the classical approaches to isolate pure chitin from the sponge skeleton. For the first time, we carried out extraction of multilayered, tube-like chitin from skeletons of cultivated Aplysina aerophoba demosponge using 1% LiOH solution at 65 °C following sonication. Surprisingly, this approach leads not only to the isolation of chitinous scaffolds but also to their dissolution and the formation of amorphous-like matter. Simultaneously, isofistularin-containing extracts have been obtained. Due to the absence of any changes between the chitin standard derived from arthropods and the sponge-derived chitin treated with LiOH under the same experimental conditions, we suggest that bromotyrosines in A. aerophoba sponge represent the target for lithium ion activity with respect to the formation of LiBr. This compound, however, is a well-recognized solubilizing reagent of diverse biopolymers including cellulose and chitosan. We propose a possible dissolution mechanism of this very special kind of sponge chitin.

Research progress on pyrolysis of nitrogen-containing biomass for fuels, materials, and chemicals production

Pyrolysis of nitrogen-containing biomass holds tremendous potential for producing varieties of high value-added products, alleviating energy depletion. Based on the research status about nitrogen-containing biomass pyrolysis, the effect of biomass feedstock composition on pyrolysis products is first introduced from the aspects of elemental analysis, proximate analysis, and biochemical composition. The properties of biomass with high and low nitrogen used in pyrolysis are briefly summarized. Then, with the pyrolysis of nitrogen-containing biomass as the core, biofuel characteristics, nitrogen migration during pyrolysis, the application prospects, unique advantages of nitrogen-doped carbon materials for catalysis, adsorption and energy storage are introduced, as well as their feasibility in producing nitrogen-containing chemicals (acetonitrile and nitrogen heterocyclic) are reviewed. The future outlook for the application of the pyrolysis of nitrogen-containing biomass, specifically, how to realize the denitrification and upgrading of bio-oil, performance improvement of nitrogen-doped carbon materials, as well as separation and purification of nitrogen-containing chemicals, are addressed.

Spinel-Derived Formation and Amorphization of Bimetallic Oxyhydroxides for Efficient Electrocatalytic Biomass Oxidation

Replacing the oxygen evolution reaction (OER) with water-assisted oxidation of organic molecules represents a promising approach for achieving sustainable electrochemical biomass utilization. Among numerous OER catalysts, spinels have received substantial attention due to their manifold compositions and valence states, yet their application in biomass conversions remains rare. Herein, a series of spinels were investigated for the selective electrooxidation of furfural and 5-hydroxymethylfurfural, two model substrates for versatile value-added chemical products. Spinel sulfides universally exhibit superior catalytic performance compared to that of spinel oxides, and further investigations show that the replacement of oxygen with sulfur led to the complete phase transition of spinel sulfides into amorphous bimetallic oxyhydroxides during electrochemical activation, serving as the active species. Excellent values of conversion rate (100%), selectivity (100%), faradaic efficiency (>95%), and stability were achieved via sulfide-derived amorphous CuCo-oxyhydroxide. Furthermore, a volcano-like correlation was established between their BEOR and OER activities based on an OER-assisted organic oxidation mechanism.

Recent Advances in the Efficient Synthesis of Useful Amines from Biomass-Based Furan Compounds and Their Derivatives over Heterogeneous Catalysts

Bio-based furanic oxygenates represent a well-known class of lignocellulosic biomass-derived platform molecules. In the presence of H2 and different nitrogen sources, these versatile building blocks can be transformed into valuable amine compounds via reductive amination or hydrogen-borrowing amination mechanisms, yet they still face many challenges due to the co-existence of many side-reactions, such as direct hydrogenation, polymerization and cyclization. Hence, catalysts with specific structures and functions are required to achieve satisfactory yields of target amines. In recent years, heterogeneous catalytic synthesis of amines from bio-based furanic oxygenates has received extensive attention. In this review, we summarize and discuss the recent significant progress in the generation of useful amines from bio-based furanic oxygenates with H2 and different nitrogen sources over heterogeneous catalysts, according to various raw materials and reaction pathways. The key factors affecting catalytic performances, such as active metals, supports, promoters, reaction solvents and conditions, as well as the possible reaction routes and catalytic reaction mechanisms are studied and discussed in depth. Special attention is paid to the structure–activity relationship, which would be helpful for the development of more efficient and stable heterogeneous catalysts. Moreover, the future research direction and development trend of the efficient synthesis for bio-based amines are prospected.

Customized valorization of waste streams by Pseudomonas putida: State-of-the-art, challenges, and future trends

Preventing catastrophic climate events warrants prompt action to delay global warming, which threatens health and food security. In this context, waste management using engineered microbes has emerged as a long-term eco-friendly solution for addressing the global climate crisis and transitioning to clean energy. Notably, Pseudomonas putida can valorize industry-derived synthetic wastes including plastics, oils, food, and agricultural waste into products of interest, and it has been extensively explored for establishing a fully circular bioeconomy through the conversion of waste into bio-based products, including platform chemicals (e.g., cis,cis-muconic and adipic acid) and biopolymers (e.g., medium-chain length polyhydroxyalkanoate). However, the efficiency of waste pretreatment technologies, capability of microbial cell factories, and practicability of synthetic biology tools remain low, posing a challenge to the industrial application of P. putida. The present review discusses the state-of-the-art, challenges, and future prospects for divergent biosynthesis of versatile products from waste-derived feedstocks using P. putida.

Direct conversion of chitin derived N-acetyl-D-glucosamine into 3-acetamido-5-acetylfuran in deep eutectic solvents

3-Acetylamino-5-acetylfuran (3A5AF) is an important nitrogen-containing fine chemical with broad application prospects and high research value. Herein, we report a novel method for the conversion of N-acetyl-d-glucosamine (NAG) to 3A5AF in the choline chloride-based deep eutectic solvents (DESs). The catalytic activities of various DESs have been smoothly screened, and DES 2 (choline chloride/PEG-200/boronic acid = 1/1/0.5) displayed the best catalytic performance. In the absence of any additional solvent, catalyst and additive, product 3A5AF was obtained in 18.3% yield after reacting at 180 °C for 15 min under atmospheric condition. In addition, DES 2 showed a good reusability. The possible reaction pathway was elucidated on the basis of the results of LC-MS and ¹³C NMR spectra. This study provided a new perspective for the application of DES in the conversion of chitin biomass.

Selective Synthesis of Oligosaccharides by Mechanochemical Hydrolysis of Chitin over a Carbon-Based Catalyst

Oligosaccharides possess fascinating functions that are applicable in a variety of fields, such as agriculture. However, the selective synthesis of oligosaccharides, especially chitin-oligosaccharides, has remained a challenge. Chitin-oligosaccharides activate the plant immune system, enabling crops to withstand pathogens without harmful agrichemicals. Here, we demonstrate the conversion of chitin to chitin-oligosaccharides using a carbon catalyst with weak acid sites and mechanical milling. The catalyst produces chitin-oligosaccharides with up to 94 % selectivity in good yields. Monte-Carlo simulations indicate that our system preferentially hydrolyzes larger chitin molecules over oligomers, thus providing the desired high selectivity. This unique kinetics is in contrast to the fact that typical catalytic systems rapidly hydrolyze oligomers to monomers. Unlike other materials carbons more strongly adsorb large polysaccharides than small oligomers, which is suitable for the selective synthesis of small oligosaccharides.

A sustainable thermochemical conversion of animal biomass to N-heterocycles

The production of high-valued organonitrogen chemicals, especially N-heterocycles, requires artificial N2 fixation accompanied by the consumption of fossil resources. To avoid the use of these energy- and resource-intensive processes, we develop a sustainable strategy to convert nitrogen-rich animal biomass into N-heterocycles through a thermochemical conversion process (TCP) under atmospheric pressure. A high percentage of N-heterocycles (87.51%) were obtained after the TCP of bovine skin due to the abundance of nitrogen-containing amino acids (e.g., glycine, proline, and l-hydroxyproline). Animal biomass with more diverse amino acid composition (e.g., muscles) yielded higher concentrations of amines/amides and nitriles after TCP. In addition, by introducing catalysts (KOH for pyrrole and Al2O3 for cyclo-Gly–Pro) to TCP, the production quantities of pyrrole and cyclo-Gly–Pro increased to 30.79 mg g−1 and 38.88 mg g−1, respectively. This approach can be used to convert the significant animal biomass waste generated annually from animal culls into valued organonitrogen chemicals while circumventing NH3-dependent and petrochemical-dependent synthesis routes.

Graphical Abstract