“H_(2)-free” demethoxylation of guaiacol in subcritical water using Pt supported on N-doped carbon catalysts:A cost-effective strategy for biomass upgrading

"H_(2)-free" HDO is a revolutionary route to circumvent the limitations of H_(2)-fed HDO reactors for biomass upgrading.This work demonstrates the viability of this economically appealing route when an adequate catalyst is implemented.Herein,we have developed a new family of Pt catalysts supported on N-doped activated carbons for the H_(2)-free HDO process of guaiacol.Several N-donors have been used to tune the catalyst’s structural and electronic properties.As a general trend,the N-promoted samples are more selective towards oxygen-depleted products.The best performing material,namely Pt/PANI-AC reached outstanding guaiacol conversion values-ca.75% at 300℃ while displaying reasonable stability for multiple recycling operations.The advanced performance is ascribed to the modified electronic and acid-base properties which favor guaiacol activation and C-O cleavage,as well as the excellent dispersion of the Pt nano particles.

Orientation controlled photogenerated carriers on selfsupporting CdS/Ni_(3)S_(2) paper toward photocatalytic hydrogen evolution and biomass upgrading

The appropriate regulation of band structure is an effective strategy in constructing efficient photocatalytic systems.Present photocatalytic system mainly employs powder photocatalysts,which makes their recovery reliant on expensive separation processes and severely limits their industrial application.Herein,we constructed a novel CdS/Ni_(3)S_(2)heterostructure using free-standing and flexible nickel fiber paper as the matrix.The regulated energy band structure achieves effective electron–hole separation.The as-synthesized flexible photocatalyst exhibits considerable photocatalytic activity toward the H_(2)evolution reaction under visible-light irradiation,with an H_(2)production rate of5.63μmol·cm^(-2)·h^(-1)(14.1 mmol·g^(-1)cat·h^(-1)according to the catalyst loading content).Additionally,the otherwisewasted excited holes simultaneously drive organic transformations to yield value-added organic products,thus markedly improving the photocatalytic H_(2)evolution rate.Such a photocatalytic system is scaled up further,where a self-supported 20 cm×25 cm sample achieves a champion H_(2)production rate of 60-80μmol·h^(-1)under practical sun irradiation.This newly developed self-supported photocatalyst produces opportunities for practical solar H2production with biomass upgrading.

Metal vacancy-enriched layered double hydroxide for biomass molecule electrooxidation coupled with hydrogen production

The electrochemical oxidation of biomass molecules coupling with hydrogen production is a promising strategy to obtain both green energy and value-added chemicals;however,this strategy is limited by the competing oxygen evolution reactions and high energy consumption.Herein,we report a hierarchical CoNi layered double hydroxides(LDHs)electrocatalyst with abundant Ni vacancies for the efficient anodic oxidation of 5-hydroxymethylfurfural(HMF)and cathodic hydrogen evolution.The unique hierarchical nanosheet structure and Ni vacancies provide outstanding activity and selectivity toward several biomass molecules because of the finely regulated electronic structure and highly-exposed active sites.In particular,a high faradaic efficiency(FE)at a high current density(99%at 100 mA cm^(-2))is achieved for HMF oxidation,and a two-electrode electrolyzer is assembled based on the Ni vacancies-enriched LDH,which realized a continuous synthesis of highly-pure 2,5-furandicarboxylic acid products with high yields(95%)and FE(90%).

N-doped carbon layer-coated Au nanocatalyst for H_(2)-free conversion of 5-hydroxymethylfurfural to 5-methylfurfural

Deoxygenative upgrading of 5-hydromethylfurfural(HMF)into valuable chemicals has attracted intensive research interest in recent years,with product selectivity control remaining an important topic.Herein,TiO_(2) supported gold catalysts coated with a thin N-doped porous carbon(NPC)layer were developed via a polydopamine-coating-carbonization strategy and utilized for pathway-specific conversion of HMF into 5-methylfurfural(5-MF)with the use of renewable formic acid(FA)as the deoxygenation reagent.The as-fabricated Au/TiO_(2)@NPC exhibited excellent catalytic performance with a high yield of 5-MF(>95%).The catalytic behavior of Au@NPC-based catalysts was shown to be correlated with the suitable combination of highly dispersed Au nanoparticles and favorable interfacial interactions in the Au@NPC core-shell hetero-nanoarchitectures,thereby facilitating the preferential esterification of HMF with FA and suppressing unproductive FA dehydrogenation,which promoted the selective formylation/decarboxylation of hydroxy-methyl group in HMF in a pathway-specific manner.The present NPC/metal interfacial engineering strategy may provide a potential guide for the rational design of advanced catalysts for a wide variety of heterogeneous catalysis processes in terms of the conversion of biomass source.

Understanding the promotional effects of trace doped Zn in Co/NC for efficient one-pot catalytic conversion of furfural to 2-methyl-tetrahydrofuran

2-methyl-tetrahydrofuran(2-MTHF)is a promising biofuel or fuel additive with excellent burning property,a versatile new-style solvent in organic synthesis,and an important medical intermediate.In this work,a one-pot selective conversion of furfural(FA)into 2-MTHF was carried out over Zn doped Co/NC catalysts.The Zn-Co/NC-1 catalyst with trace Zn dopant(0.38 wt%)exhibited the best performance(yield of 2-MTHF:93.8%).According to the characterizations,it was found that the Zn not only incorporates into the carbon support but also partially dopes into Co nanoparticles.Subsequently,theoretical calculations demonstrated that the doping of Zn in carbon support can effectively enhance the electron transfer from the support to the metallic Co particle,leading to the electron-rich Co surface.The presence of Zn was found to promote the dissociation of hydrogen and to lower the diffusion barrier of hydrogen atom,in favor of the hydrogenation/hydrodeoxygenation processes.Furthermore,the Zn doped models exhibit much lower barrier in breaking C–OH bond of FOL,resulting in higher activity for hydrodeoxygenation of FOL.These theoretical results are consistent with the in situ FT-IR analysis of adsorption substrates and intermediates over Zn doped catalyst.This work reveals the mechanism of dopant Zn tailoring the electronic structure and catalytic performance of active sites,providing a deep insight into the design of economical and high-performance catalysts for hydrogenation/hydrodeoxygenation of biomass feedstocks.

Anodic Electrosynthesis of Amide from Alcohol and Ammonia

Amide is essential in biologically active compounds,synthetic materials,and building blocks.However,conventional amide production relies on energyintensive consumption and activating agents that modulate processes to construct the C–N bond.Herein,for the first time,we have successfully realized the formation of amides at industrial current density via the anodic coelectrolysis of alcohol and ammonia under ambient conditions.We have proved thatmodulation of the interface microenvironment concentration of nucleophile by electrolyte engineering can regulate the reaction pathways of amides rather than acetic acids.The C-N coupling strategy can be further extended to the electrosynthesis of the long-chain and aryl-ring amide with high selectivity by replacing ammonia with amine.Our work opens up a vast store of information on the utilization of biomass alcohol for high-value N-containing chemicals via an electrocatalytic C-N coupling reaction.

Electro-oxidation of 5-hydroxymethylfurfural in a low-concentrated alkaline electrolyte by enhancing hydroxyl adsorption over a single-atom supported catalyst

Electrocatalytic oxidation of 5-hydroxymethylfurfural(HMF)to 2,5-furandicarboxylic acid(FDCA),a sustainable strategy to produce bio-based plastic monomer,is always conducted in a high-concentration alkaline solution(1.0 mol L^(-1)KOH)for high activity.However,such high concentration of alkali poses challenges including HMF degradation and high operation costs associated with product separation.Herein,we report a single-atom-ruthenium supported on Co3O4(Ru1-Co3O4)as a catalyst that works efficiently in a low-concentration alkaline electrolyte(0.1 mol L^(-1)KOH),exhibiting a low potential of 1.191 V versus a reversible hydrogen electrode to achieve 10 m A cm^(-2)in 0.1 mol L^(-1)KOH,which outperforms previous catalysts.Electrochemical studies demonstrate that single-atom-Ru significantly enhances hydroxyl(OH-)adsorption with insufficient OH-supply,thus improving HMF oxidation.To showcase the potential of Ru1-Co3O4catalyst,we demonstrate its high efficiency in a flow reactor under industrially relevant conditions.Eventually,techno-economic analysis shows that substitution of the conventional1.0 mol L^(-1)KOH with 0.1 mol L^(-1)KOH electrolyte may significantly reduce the minimum selling price of FDCA by 21.0%.This work demonstrates an efficient catalyst design for electrooxidation of biomass working without using strong alkaline electrolyte that may contribute to more economic biomass electro-valorization.

Recent advances in non-noble electrocatalysts for oxidative valorization of biomass derivatives

Electrocatalysis is deemed as a promising approach for sustainable energy conversion and chemical production.Although a variety of cathode reactions(e.g.,hydrogen evolution and CO_(2)/N_(2)reduction)produce valuable fuels and chemicals,the extensively studied oxygen evolution reaction(OER)at anode only generates O_(2),which is not a high-value product.Substituting the OER with thermodynamically more favorable biomass derivative oxidation reactions(BDORs)not only enables energy-saving electrocatalysis,but also provides value-added anode products.Recent achievements have demonstrated that non-noble electrocatalysts are promising for BDORs.Herein,we provide a comprehensive review on recent achievements in the field of electrochemical BDORs catalyzed by non-noble catalysts.We start by summarizing the electrocatalytic oxidation of different types of biomass-derived substrates,aiming to show the advantages of the electrocatalytic pathway and to introduce the state-of-the-art non-noble catalysts.The reaction mechanisms of non-noble-material-catalyzed BDORs are then summarized and classified into three types according to the acceptor of hydrogen species during the dehydrogenation of biomass derivatives.Subsequently,discussions are devoted to the strategies for promoting the performances of non-noble electrocatalysts.Finally,we propose our opinions regarding future trends and major challenges in this field.