Biomass Upgrading Research Articles

Cu/CuOx@C for efficient selective transfer hydrogenation of furfural to furfuryl alcohol with formic acid

AbstractBackgroundCatalytic transfer hydrogenation has been increasingly employed as an effective and safe method for biomass upgrading; however, relying on biomass‐derived formic acid (FA) as hydrogen source has rarely been studied, especially in the production of furfuryl alcohol (FOL) from biomass‐derived furfural (FF) via selective hydrogenation, which is challenging due to diverse unsaturated groups. Herein, in situ encapsulation and stabilization of Cu/CuOx in a porous carbon matrix (Cu/CuOx@C) was reported for the first time and applied in the hydrogenation of FF to FOL with FA.ResultsVarious analytical techniques were used to characterize the effect of pyrolysis temperature on Cu/CuOx@C, since the temperature can be adjusted to control the reduction of the catalyst to give different Cu0/Cun+ ratios. The optimal catalyst Cu/CuOx@C‐450 gave a 99.1% FF conversion and 98% FOL selectivity under suitable reaction conditions, exhibiting excellent activity that was even better than those of noble metal catalysts. Further, density functional theory calculations were used to reveal the effect of Cu species on FA decomposition and final catalytic performance.ConclusionThe catalytic activity of Cu/CuOx@C was influenced by the pyrolysis temperature of the catalyst precursor, and its good performance was mainly attributed to a high dispersion of accessible catalytic Cu/CuOx nanoparticles on the porous carbon and to an appropriate Cu0/Cun+ ratio. © 2022 Society of Chemical Industry (SCI).

Biorefinery upgrading of herbaceous biomass to renewable hydrocarbon fuels, Part 1: Process modeling and mass balance analysis

Process simulation has long been a well-established tool to track key operational, design, and mass and energy balance metrics for pre-commercial technologies such as advanced lignocellulosic biofuels. While tools such as this are well-documented in the public literature around 2nd-generation cellulosic ethanol technologies (which have been scaled up to commercial deployment to some degree over the past decade), such models and analysis information remain more sparse for more complex biorefinery pathways focused on producing drop-in hydrocarbon fuels and blend-stocks, particularly regarding information required to support air emissions or other environmental analysis. In this work, we summarize key details for an established “design case” modeling the conversion of herbaceous lignocellulosic biomass into a renewable diesel hydrocarbon blend-stock based on a representative lipid pathway from oleaginous yeast. The process is based on a biochemical deconstruction and upgrading approach utilizing deacetylation and dilute acid pretreatment, followed by enzymatic hydrolysis, fermentation, and catalytic upgrading of hydrolysate sugars to fuels. We provide key mass and energy balance outputs from the process models, with accompanying stream tables and component-level flowrates. A total of 12 model scenarios are presented spanning two feedstocks, three biorefinery scales, and two processing approaches for the lignin/residual solids waste streams. This “Part 1” manuscript presents the resulting impacts across the 12 cases on fuel yields and key output streams, focused here on direct biorefinery air emissions for selected components including CO 2 as well as sulfur (SOx) and nitrogen oxides (NOx). In the context of cleaner production, the latter focus on selected biorefinery air emission outputs establishes an initial baseline estimate and accompanying framework of the model cases, upon which an accompanying “Part 2” study will build to refine the values for these and other air pollutants across these scenarios, also considering mitigation options to comply with applicable regulatory standards. We also highlight further optimization opportunities based on potential tradeoffs identified here between air emissions versus life-cycle greenhouse gas profiles attributed to the disposition of lignin/residual solids.

Biorefinery upgrading of herbaceous biomass to renewable hydrocarbon fuels, Part 2: Air pollutant emissions and permitting implications

The development of advanced biofuel production facilities is still at a nascent stage, and the biorefineries could face challenges in obtaining air permits required for their construction and operation because they are novel emission sources. To fill gaps in knowledge regarding potential emissions, we perform a detailed federal regulatory analysis and estimate air pollutant emissions for an advanced biorefinery that produces renewable diesel blendstock (RDB) from lignocellulosic biomass via aerobic respiration documented in Part 1 of the paper. We evaluate 12 design permutations that include two feedstocks, a uniform format blend (UFB) and corn stover; three biorefinery scales, 2,000, 5,200, and 9,100 dry metric tons per day (dmtd) of lignocellulosic biomass feed; and two lignin uses, as either a boiler fuel or for pellet production. We also evaluate 6 additional design permutations by incorporating non-emitting renewable power, which could reduce up to 63% carbon monoxide (CO) and nitrogen oxides (NO x ) each, 21% volatile organic compounds (VOC), and 43% hazardous air pollutants (HAP) as opposed to on-site power production, for biorefineries that produce pellets, using either UFB or corn stover. Our results indicate that all 18 design permutations would be classified as a major source under the Clean Air Act's New Source Review program without additional emission controls. Compared to using lignin as a boiler fuel, diverting lignin for pellet production reduces the emissions of CO up to 88%, NO x up to 73%, sulfur dioxide (SO 2 ) up to 99%, VOCs up to 72%, and HAPs up to 66%. Additionally, we explore control options that could further reduce emissions and assess whether reductions are enough to achieve minor source classification. Insights from our analysis can help biorefinery developers and regulators develop permitting strategies to mitigate investment risks. • Air emissions from 12 biorefinery process design variations are quantified. • Biorefineries would be classified as major sources without additional controls. • Control options are available for compliance with applicable federal regulations. • Diverting lignin for pellet production could reduce air emissions by at least 66%. • Integrating non-emitting renewable power could help achieve minor source.

Unleashing lignin potential through the dithionite-assisted organosolv fractionation of lignocellulosic biomass

The development of biomass pretreatment approaches that, next to (hemi)cellulose valorization, aim at the conversion of lignin to chemicals is essential for the long-term success of a biorefinery. Herein, we discuss a dithionite-assisted organosolv fractionation (DAOF) of lignocellulose in n-butanol and water to produce cellulosic pulp and mono-/oligo-aromatics. The study frames the technicalities of this biorefinery process and relates them to the features of the obtained product streams. We comprehensively identify and quantify all products of interest: solid pulp (acid hydrolysis-HPLC, ATR-FTIR, XRD, SEM, enzymatic hydrolysis-HPLC), lignin derivatives (GPC, GC–MS/FID, 1H–13C HSQC NMR, ICP-AES), and carbohydrate derivatives (HPLC). These results were used for inspecting the economic feasibility of DAOF. In the best process configuration, a high yield of monophenolics was reached (∼20 wt%, based on acid insoluble lignin in birch sawdust). Various other lignocellulosic feedstocks were also explored, showing that DAOF is particularly effective on hardwood and herbaceous biomass. Overall, this study demonstrates that DAOF is a viable fractionation method for the sustainable upgrading of lignocellulosic biomass.

Effect of torrefaction on the evolution of carbon and nitrogen during chemical looping gasification of rapeseed cake

Chemical looping gasification (CLG) is a novel approach to efficiently convert rapeseed cake (RC) to tunable syngas and NH3. However, the low energy density of RC seriously hinders its utilization. Meanwhile, torrefaction is an effective pretreatment for biomass upgrading. Hence, the combination of torrefaction with CLG is proposed as an alternative technology to efficiently utilize RC. In this work, the effect of torrefaction temperature on the evolution behaviors of carbon and nitrogen in CLG of RC with Ca2Fe2O5 OC was systematically investigated using TG-FTIR. Results show that torrefaction can effectively improve the physiochemical properties of RC. The torrefied RC possesses higher energy density and HHV, and lower atomic H/C and O/C ratios. Additionally, higher torrefaction temperature can facilitate the thermal degradations of N-IN and labile NP, with the productions of NH3 and HCN. During CLG, the rise of OC/Fuel mass ratio can increase the yields of the major gases (CO2, CO, CH4, NH3 and HCN), owing to both the oxidative effect of the lattice oxygen (O*) and the catalytic effects of Fe3+ and Ca2+ in OC. Moreover, torrefaction pretreatment can improve the CLG behavior of RC and the optimal torrefaction temperature is 250 °C, attributing to the improvement of fuel stability after torrefaction. Besides, torrefaction can marginally reduce the yields of the major nitrogen species (NH3 and HCN). This is ascribed to both the more stable structure of heterocyclic-N and the insufficiency of H radical in the torrefied RC compared to the raw. These findings provide a feasible guidance for the effective insight in nitrogen evolution during CLG coupled with torrefaction, and thereafter for the efficient utilization of biomass.

Supported Ru nanocatalyst over phosphotungstate intercalated Zn-Al layered double hydroxide derived mixed metal oxides for efficient hydrodeoxygenation of guaiacol

In this work, a strategy for rational design of high-performance heterogenous supported Ru nanocatalysts over mixed metal oxides for aqueous phase partial hydrodeoxygenation (HDO) of guaiacol in the batch reactor was developed taking advantage of supramolecular structure of Zn-Al layered double hydroxides (LDHs) with different interlayer anions. It was interestingly found that in the case of phosphotungstate intercalated ZnAl-LDH as the support precursor, strong interactions between Ru species and intercalated LDH-derived mixed metal oxide supports could be formed, in addition to the formation of surface reductive ZnWOx component and P-O species. Notably, as-fabricated supported Ru nanocatalyst showed much higher activity in the aqueous phase HDO of guaiacol to produce cyclohexanol at an extraordinarily low Ru/guaiacol molar ratio of 0.0009, along with a higher cyclohexanol yield of ∼86% under reaction conditions (250 °C, 2.0 MPa initial H2 pressure), compared to other two supported Ru ones over mixed metal oxides derived from tungstate- and nitrate-intercalated ZnAl-LDH precursors (cyclohexanol yield of 29.7 and 10.1%, respectively). Studies on structure-property correlations revealed that surface defective and acidic sites facilitated the activation of guaiacol and phenol intermediate, thereby enabling the catalyst with a strong ability to break Cring−OCH3 bond and promote the ring hydrogenation. This finding provides a promising way to tune surface structures of metal-based catalysts for the upgrading of biomass.

Co-Solvent Assisted Hydrothermal Liquefaction of Algal Biomass and Biocrude Upgrading

This study reports the hydrothermal liquefaction (HTL) of microalgae Spirulina platenesis in the presence of alcohol or formic acid co-solvents. HTL runs are performed in a 1.8-L batch reactor at 300 °C using an alcohol (methanol and ethanol) or formic acid co-solvent. Consequently, hydrodeoxygenation (HDO) of resultant algal biocrude is performed at 350 °C for 2 h under high hydrogen pressure (~725 psi) using the Ru/C catalyst. The HTL results are compared with the control HTL run performed in water only. The results of the study show that the addition of co-solvents leads to a 30–63% increased biocrude yield over the control HTL run. Formic acid results in a 59.0% yield of biocrude, the highest amongst all co-solvents tested. Resultant biocrudes from formic acid-assisted and ethanol-assisted HTL runs have 21.6% and 3.8–11.0% higher energy content, respectively, than that of the control run. However, that of the methanol-assisted HTL results in biocrude with 4.2–9.0% lower energy density. Viscosity of biocrude from methanol- or ethanol-assisted HTL is higher than the control HTL but formic acid-assisted HTL results in a less viscous biocrude product. In addition, the HDO study leads to a 40.6% yield of upgraded oil, which is characterized by a higher net energy content and lower O/C and N/C ratios when compared to the initial HTL biocrude.

Coordination environment tuning of nickel sites by oxyanions to optimize methanol electro-oxidation activity

To achieve zero-carbon economy, advanced anode catalysts are desirable for hydrogen production and biomass upgrading powered by renewable energy. Ni-based non-precious electrocatalysts are considered as potential candidates because of intrinsic redox attributes, but in-depth understanding and rational design of Ni site coordination still remain challenging. Here, we perform anodic electrochemical oxidation of Ni-metalloids (NiPx, NiSx, and NiSex) to in-situ construct different oxyanion-coordinated amorphous nickel oxyhydroxides (NiOOH-TOx), among which NiOOH-POx shows optimal local coordination environment and boosts electrocatalytic activity of Ni sites towards selective oxidation of methanol to formate. Experiments and theoretical results demonstrate that NiOOH-POx possesses improved adsorption of OH* and methanol, and favors the formation of CH3O* intermediates. The coordinated phosphate oxyanions effectively tailor the d band center of Ni sites and increases Ni-O covalency, promoting the catalytic activity. This study provides additional insights into modulation of active-center coordination environment via oxyanions for organic molecules transformation.

Toward rational design of supported vanadia catalysts of lignin conversion to phenol

In sustainable chemical engineering, catalytic upgrading of lignocellulosic biomass has recently gained attention for producing renewable platform chemicals. To achieve maximal biomass utilization, upgrading the underutilized lignin components is essential. Among various catalysts for lignin upgrading, supported vanadia (V2O5) catalysts are promising because of their cost-effectiveness and tunability of either dopant metals or catalyst supports. Here, computational studies are conducted to derive rational design guidelines of supported V2O5 catalysts for accomplishing the high catalytic activity of lignin upgrading to phenol, a key compound for producing bioplastics and biofuel blendstocks. Guaiacol was used as the model compound since it comprises the highest portion of depolymerized lignin. Computational mechanistic studies for the catalytic guaiacol conversion to phenol were performed for the V2O5 catalysts on Titania (TiO2) and silica (SiO2) to explain higher experimental phenol yields on V2O5/SiO2 than V2O5/TiO2. The hydrogen migration from the methoxy group to the aryl ring was identified as a rate-determining step, and the overall activation energies on the two catalysts were compared. A structural analysis was carried out for the catalysts and rate-determining transition states to gain further insights from mechanistic studies. It was concluded that the tilt angle of the aryl group in the hydrogen migration transition state is a key descriptor determining the catalytic activity of phenol formation. These features correlate well with activation energies and experimental phenol yields, indicating that they provide design guidelines for supported metal catalysts for lignin upgrading before experiments.

Oxidative torrefaction of microalga Nannochloropsis Oceanica activated by potassium carbonate for solid biofuel production

Oxidative torrefaction is a promising way for biomass upgrading and solid biofuel production. Alkali metals are considered to be efficient activators for enhancing biofuel upgrading during the thermal reaction process. Herein, the microalga Nannochloropsis Oceanica is selected as the feedstock for assessing potassium carbonate activated effect on solid biofuel production through oxidative torrefaction. The potential of potassium carbonate on microalgal biofuel properties upgrading is deeply explored. SEM observation and BET analysis show that torrefied microalgae can be transformed from a spherical structure with wrinkles to smaller particles with larger surface areas and higher total pore volumes, implying that potassium carbonate is a promising porogen. Moreover, potassium carbonate can significantly change the DTG curve at the temperatures of 250 °C and 300 °C from one peak to two peaks, inferring that the activated effect of potassium carbonate occurs on the torrefied microalgae. 13C NMR analysis reveals that the microalgal components significantly change as the torrefaction severity increases, with the decomposition of carbohydrate and protein components. When the potassium carbonate ratio increases from 0:1 to 1:1, the graphitization degree increase from 3.065 to 1.262, along with the increase in the HHV of solid biofuel from 25.024 MJ kg−1 to 31.890 MJ kg−1. In total, this study has comprehensively revealed the activated effect of potassium carbonate on improving the properties of microalgal solid biofuel.

Catalytic Transfer Hydrogenation of 5-Hydroxymethylfurfural with Primary Alcohols over Skeletal CuZnAl Catalysts.

Catalytic transfer hydrogenation (CTH) with alcohols has been increasingly employed as effective tool for biomass upgrading, however, relying predominantly on secondary alcohols. Herein, for the first time skeletal CuZnAl catalysts were employed for the activation of a primary alcohol, ethanol, for the hydrogenation 5-hydroxymethylfurfual (HMF) to 2,5-bis(hydroxymethyl)furan (BHMF) under a mild condition. The catalysts were extensively characterized to reveal the structure characteristics and surface compositions. Over 90 % yield of BHMF were obtained over the optimal CuZnAl-0.5 catalyst at the reaction temperatures of 100-120 °C. Reaction kinetics indicated a competitive adsorption between HMF and ethanol on the catalyst surface, with the activation of ethanol being the rate-determining step (apparent activation energy Ea =70.9 kJ mol-1 ). Preliminary adsorption investigation using combined attenuated total reflectance infrared spectroscopy and density functional theory calculation proposed a η2 -(O,O)-aldehyde, furoxy perpendicular configuration of HMF on catalyst surface. The catalyst was further applied to the CTH of various aldehydes to the corresponding alcohols with high yields, demonstrating the broad applicability of the current system.

Recent progress in Biomass-derived nanoelectrocatalysts for the sustainable energy development

The changing global approach for protecting the planet and turning to a low-carbon economy has made the growing demand for biomasses at the core of biochemistry. Biomass contains all the substances in nature that in the recent past were living things, made from living organisms or their wastes. Biomass is carbon-based and is a mixture of organic molecules, including hydrogen, usually oxygen, and often nitrogen, and small amounts of other atoms such as alkali metals, alkaline earth metals, and heavy metals. Production and consumption of biomasses grew in sustainable procedures do not cause a net change in the CO2 content of the atmosphere. So, the biomasses can be regarded as carbon neutral due to the mentioned net carbon cycle they involve. Energy production from biomass sources is utilized to generate electricity and heat. These sources are renewable sources and CO2 production of these sources is natural and does not produce greenhouse gases. The development of practical techniques for sustainable energy generation from biomass is one of novel strategy to overcome air pollution and move towards the sustainable bioeconomy. This study reviews recent progress in Biomass-derived nanoelectrocatalysts for the sustainable energy development that includes biomass-based electrocatalyst synthesis, biomass-based nanoelectrocatalysts for water splitting, and biomass-based nanoelectrocatalysts for fuel cells. Finally provides future perspectives to motivate future research such as the necessity to increase agricultural and so food production while reducing inputs to balance biomass valorization for energy production versus biomass upgrading, and to develop practical techniques for cheap pretreatment and metabolic engineering of lignocellulosic and efficient strategies for the commercial-scale production of lignocellulosic based-biofuels.

Design and Application of a High-Surface-Area Mesoporous δ-MnO2 Electrocatalyst for Biomass Oxidative Valorization

The design and application of electrocatalysts based on Earth-abundant transition-metal oxides for biomass valorization remain relatively underexplored. Here, we report a nanocasting route to synthesize mesoporous δ-MnO2 with a high surface area (198 m2/g), high pore volume, and narrow pore size distributions to address this issue. By taking structural advantages of mesoporous oxides, this mesoporous δ-MnO2 is employed as a highly efficient, selective, and robust anode for 5-hydroxymethylfurfural (HMF) electrochemical oxidation to 2,5-furandicarboxylic acid (FDCA) with a high yield (98%) and faradic efficiency (98%) under alkaline conditions. The electrocatalyst is also effective for the more difficult HMF electro-oxidation under acidic conditions, forming both FDCA and maleic acid as value-added products in a potential-dependent manner. Experimental results combined with theoretical calculations provide insights into the reaction kinetics and the reaction pathways of electrochemical HMF oxidation over this advanced electrocatalyst. This work thus showcases the rational design of non-noble metal electrodes for multiple applications, such as oxygen evolution, water electrolysis, and biomass upgrading with high energy efficiency.

Life cycle assessment of torrefied cornstalk pellets combustion heating system

Biomass combustion for heating is an important method to utilize raw biomass resources, especially stalks with low calorific value. Torrefaction and compression molding are the effective and common pretreatments for biomass upgrading. In this study, the resources, energy consumption and environmental impact of torrefied cornstalk pellets combustion heating system were studied using the Life Cycle Assessment (LCA) method. The scope of the LCA includes 5 stages: biomass planting and collection, transportation, plant construction, pretreatment, and combustion heating. The resource consumption assessment showed a total energy output of the life cycle system corresponding to 19.7 GJ (The utilization of by-products was not considered), while the total energy input was 2671.3 MJ/t, and the net energy was 17028.69 MJ/t. The estimated energy input–output ratio was 7.3. The increased value of fuel energy of cornstalk pellets after torrefaction pretreatment was greater than the energy consumption during the same process. The results of energy consumption showed that the maximum energy input was identified as the planting and collection stage (1246.54 MJ/t), among which the top two are the nitrogen fertilizer energy input (56%) and the agricultural machinery fuel consumption (27%). The nitrogen fertilizer input represents 84.17% of the total energy input of fertilizer. The environmental impact assessment showed that the total GWP of the system is −175.806 kg CO2eq, indicating that the whole life cycle of the system can reduce greenhouse gas emissions. Acidification and photochemical oxidation potentials become the main factors influencing the ecological footprint of the system. Thus, considering the comprehensive impact of energy consumption and environmental emission, it is feasible to use torrefied cornstalk pellets as fuel for heating.

Hydrogen Spillover-Enhanced Heterogeneously Catalyzed Hydrodeoxygenation for Biomass Upgrading.

Hydrodeoxygenation (HDO) is regarded as a promising technology for biomass upgrading to obtain sustainable and competitive chemicals and fuels. In fact, biomass HDO over heterogeneous solid catalysts is often accompanied by the phenomenon of hydrogen spillover, which further affects the catalytic performance. Thus, it is necessary to gain in-depth understand the promoting effect of hydrogen spillover in the biomass HDO process to obtain desired conversion and selectivity. This Review summarized the extensive research on hydrogen spillover in biomass refining and discussed in detail the regulation mechanism of hydrogen spillover in biomass HDO process, mainly by regulating different active center sites on catalyst supports, such as metal sites, acid sites, surface functional groups, and defective sites, which exhibit independent and synergistic characteristics promoting catalyst activity, selectivity, and stability. Finally, the prospective of hydrogen spillover in biomass HDO applications was critically evaluated, and the key technical challenges in developing "hydrogen-free" HDO and upgrading biofuels were highlighted. The presentation of hydrogen spillover-enhanced catalytic biomass HDO in this Review will hopefully provide insight and guidance for further development of efficient catalysts and preparation of high-value chemicals in the future.

Self-support semi-hollow carbon nanosphere supported palladium catalyst for biomass upgrading

Catalytic removal of oxygen from biomass by hydrodeoxygenation (HDO) as a promising process has been pursued for efficient utilization of biomass resources. Here we report a self-support semi-hollow carbon nanospheres (SHCN) supported palladium (Pd) catalyst for vanillin HDO under mild conditions. The shell-void-core structure of carbon nanospheres originates from the modulation of growth kinetics of resorcinol/formaldehyde resin precursors by a given volume of acetone. Notably, 0.5%Pd/SHCN-60 (acetone of 60 mL) catalyst exhibits >99.9% of vanillin conversion and creosol selectivity under 25 °C and 0.1 MPa of H2. The good catalytic results can derive from the self-support hollow carbon support and active metallic Pd. Raman results show that 0.5%Pd/SHCN-60 possesses the most abundant defect carbon (AD1/AG = 2.02), which leads to the small particle size (mean size of 2.9 nm) and well dispersion (29.5%) of Pd. Higher H2-desorption temperature (∼440 °C) of 0.5%Pd/SHCN-60 by H2-TPD demonstrates the strong interaction of Pd-defect carbon. The strong interaction favors the hydrogen storage and activation of substrates under low pressure of H2 and reaction temperature, which improves the hydrogenation and hydrogenolysis. Additionally, the contribution of unique core structure to support the shell to enhance mechanical stability leads to intact morphology of catalyst and stable catalytic performance after reused six times. This investigation can provide a design idea of carbon-based catalysts for mild HDO.

Selective hydrogenation of reducing sugars over SiO2@Ni/NiO hetero-structured nanoreactor in Mg-driven aqueous phase

Selective hydrogenation is of growing interest in biomass upgrading to be performed over non-precious metal-based catalyst in aqueous phase. Herein, a nickel/nickel oxide hetero-structural catalyst to reducing sugars hydrogenation is designed based on the tailored interfacial synergy and structural composition. Such synergistic silica @ nickel/nickel oxide (SiO2@Ni/NiO) with core–shell structure features in i) interconnected tubes on the shell offering spatial restriction to hydrogen attraction and reactant diffusion, ii) hetero-interfaced Ni/NiO shell balancing the H2 and glucose adsorption chemically, iii) the core shell catalyst providing nano-reactor for reactant enrichment, furthering improving the utilization of nickel active sites. Furthermore, the high solubility of in-situ generated H2 driven by Mg in this aqueous phase hydrogenation system greatly assist the interaction among the reactants. The SiO2@Ni/NiO catalyst exhibits high activity in glucose hydrogenation, under which the conversion rate and sorbitol selectivity can achieve 99 % and 90 % under mild condition of 393 K for 3 h, respectively. It also shows remarkable reuse ability and wide application scope to sugars hydrogenation in this in-situ hydrogen generation process. This proposal gains insights to cooperative catalyst design on chemical composition and nanostructure for advancing biomass-based sugars hydrogenation process.

Sustainable biomass upgrading coupled with H2 generation over in-situ oxidized Co3O4 electrocatalysts

Substituting overall water splitting with simultaneous biomass upgrading and H2 evolution has drawn tremendous attention due to the lower energy barrier and higher safety. Developing a cheap, efficient, and durable electrocatalyst with dual function is crucial to this novel coupling system. Herein, we propose the in-situ electrochemical tuning nonporous CoSx to hydrangea-like Co3O4 as a highly effective versatile electrocatalyst for the first time. Due to the defective structures and abundant electroactive sites, the Co3O4 catalyst achieved a complete conversion of 5-hydroxymethylfurfural (HMF) to 2,5-furandicarboxylic acid (FDCA) with 93.2% yield and 92.9% faradaic efficiency (FE), as well as a pure hydrogen evolution with 99.8% FE. Interestingly, it harvested a better performance with 95.8% FDCA yield for electro-oxidation of the more stable 2,5-bis(hydroxymethyl)furan (BHMF). Finally, a solar-driven integration reaction was constructed for the first time using the photovoltaic electrocatalysis (PVEC) of BHMF for the efficient and sustainable production of FDCA and H2.

Viscosity reduction of heavy crude oil by co-heating with hydrothermal liquid product of cotton stalk

Abstract Hydrothermal process (HT) is an economical and simple method in upgrading agriculture wastes. The liquid product obtained from HT is interesting because of abundant active chemical group. The present work tried to co-heat the HT liquid product of cotton stalk (CS) with heavy crude oil to reduce its viscosity. The optimization study was performed to obtain the best condition of co-heating and mechanism study was completed by comparing the viscosity reduction efficiency and analyzing group composition of crude oil before and after co-heating with HT liquid products of CS, cellulose, hemicellulose and lignin. The results show that the crude oil viscosity reduced obviously after co-heating with CS-HT liquid product under the optimized condition (220°C, 1 h, 3 g treatment liquid, 30 ml crude oil). The preliminary mechanism study results suggest that the main function component of CS that cause viscosity reduction of heavy oil is lignin. The current work provides a new idea of lignocellulosic biomass upgrading and heavy crude oil viscosity reduction.

Transforming Electrocatalytic Biomass Upgrading and Hydrogen Production from Electricity Input to Electricity Output

Integrating biomass upgrading and hydrogen production in an electrocatalytic system is attractive both environmentally and in terms of sustainability. Conventional electrolyser systems coupling anodic biosubstrate electrooxidation with hydrogen evolution reaction usually require electricity input. Herein, we describe the development of an electrocatalytic system for simultaneous biomass upgrading, hydrogen production, and electricity generation. In contrast to conventional furfural electrooxidation, the employed low-potential furfural oxidation enabled the hydrogen atom of the aldehyde group to be released as gaseous hydrogen at the anode at a low potential of approximately 0 VRHE (vs. RHE). The integrated electrocatalytic system could generate electricity of about 2 kWh per cubic meter of hydrogen produced. This study may provide a transformative technology to convert electrocatalytic biomass upgrading and hydrogen production from a process requiring electricity input into a process to generate electricity.