Hydrogenation Process Research Articles

Design and Synthesis of a Novel Catalytic System Based on Pd Supported on Alumina Extrudates for Hydrotreating of PAO Lubricants

ABSTRACTThe development of hydrogenation processes for polyalphaolefin (PAO) lubricants, which hold commercialization potential, is a challenging endeavor. Here, we synthesized and characterized rod‐shaped γ‐alumina supported Pd catalyst for PAO hydrofinishing, comparing it with γ‐alumina supported Ni catalyst. Results indicated that Pd/Al2O3 catalyst efficiently promoted PAO hydrofinishing, whereas Ni‐based catalyst exhibited lower activity. Optimization of reaction variables using the one‐factor‐at‐a‐time method revealed that hydrogenated polyalphaolefin could be achieved with a 90% yield using a 5 wt.% catalyst, a hydrogen pressure of 12 bar, at 130°C after 7 h. The superior performance of the fabricated catalysts, coupled with the use of rod‐shaped alumina suitable for large‐scale hydrogenation reactors, suggests the versatility of the process for potential commercialization. Additionally, the higher performance of Pd/alumina compared to Ni/alumina catalyst was computationally assessed at the molecular level using DFT methods.

Advancements in Cobalt-Based Catalysts for Enhanced CO2 Hydrogenation: Mechanisms, Applications, and Future Directions: A Short Review

In 2020, China put forward the national energy and economic development strategy goal of “carbon peak and carbon neutrality”; in this context, the hydrogenation of carbon dioxide into clean energy and high-value-added chemicals can effectively alleviate the current environmental pressure. This process represents a crucial avenue for the advancement of green energy and the realisation of a sustainable energy development strategy. Among the efficient catalysts designed for CO2 hydrogenation reactions, transition metal cobalt has garnered extensive attention from researchers due to its relatively abundant reserves and low economic cost. This paper first introduces the thermodynamic process of carbon dioxide hydrogenation and discusses methods to improve the efficiency of the catalytic reaction from a thermodynamic perspective. It then briefly describes the reaction mechanism of cobalt-based catalysts in the carbon dioxide hydrogenation reaction. Based on this understanding, this paper reviews recent research on the application of cobalt-based catalysts in the hydrogenation of carbon dioxide to produce methane, hydrocarbon chemicals, and alcohols. Finally, the methods to improve the catalytic efficiency of these catalysts are discussed, and future research directions are proposed.

Preparation of phosphorus-doped Cu-based catalysts by electrodeposition modulates *CHxO adsorption to facilitate electrocatalytic reduction of CO2 to CH4

Catalysts for the generation of methane in electrochemical CO2 reduction reactions (CO2RR) must have suitable adsorption energies for the intermediate products. In this study, we used a one-step electrodeposition method to prepare nitrogen(N) and phosphorus(P)-doped copper(Cu)-based catalysts. The introduction of P to the catalyst resulted in a significant change in the CO2RR pathway, leading to efficient and highly selective methane production. The Cu-N2-P2 electrocatalyst exhibits a CH4 Faradaic efficiency (FE) of 73 % at a potential of −1.6 V vs RHE, and it was found to be more effective in promoting the hydrogenation process of *CHO-*CH2O-*CH3O, which was confirmed by in-situ IR, X-ray absorption techniques and DFT calculations. P serves as the primary electron donation site in the catalyst, thereby influencing the charge distribution properties of the surrounding Cu atoms. This, in turn, facilitates the regulation of intermediate adsorption, representing the primary factor in the notable enhancement of methane selectivity.

Surface ion-exchange induced Bi-rich Bi12O17Cl2/BiOCOOH/Bi2MoO6 heterojunction with oxygen vacancies for enhanced photocatalytic nitrogen fixation

Photocatalytic nitrogen reduction presents a promising technology for environmentally friendly ammonia synthesis under mild conditions. However, the performance of photocatalysts is often hindered by high charge carrier recombination and insufficient adsorption and activation of nitrogen molecules. A novel Bi12O17Cl2/BiOCOOH/Bi2MoO6 heterojunction photocatalyst was successful synthesis through surface ion-exchange technique by potassium chloride. The introduction of Bi-rich Bi12O17Cl2 on BiOCOOH/Bi2MoO6 heterojunction not only improves electron transfer efficiency due to the dual type-II heterojunction effect but also facilitates on-site N2 adsorption and activation for solar ammonia production by promoting oxygen vacancies. The high photocatalytic nitrogen fixation activity of the Bi12O17Cl2/BiOCOOH/Bi2MoO6 was 107.78 μmol g−1 h−1 without any sacrificial agent. DFT calculations indicate that oxygen vacancies serve as the active site for adsorbed N2, the hydrogenation process preferentially forms on the distal N2 atom with a lower activation energy about 0.6 eV. Therefore, the combination of oxygen vacancies and band engineering accelerates the production of ammonia. This endeavor holds the potential to unleash the capabilities of engineering for Bi-rich heterojunctions materials with oxygen vacancies, thereby achieving high-efficiency solar-driven N2-to-NH3 conversion in aqueous environments.

Rationally Designing Interfacial Cu-ZnO/SiO2 catalysts for mitigation of adverse effects of water in ethyl acetate hydrogenation reactions

In heterogeneous hydrogenation reactions, the influence of water on catalytic performance is substantial, often exerting a negative impact due to competitive adsorption with reactants or intermediates. In this investigation, ZnO was introduced into the Cu/SiO2 catalyst to alleviate adverse effects of water, stemming from its preferential adsorption on active Cu+ sites. The modifications in textural properties were monitored using various characterization techniques, including H2-TPR, N2O titration, BET, and TEM. The experimental findings, coupled with analyses utilizing XRD, XPS, UV–Vis and in-situ DRIFT, elucidated that high Cu+ contents were not responsible for catalytic performance improvement, while the enhanced localization of the d-orbitals for Cu+ and surface synergism between active Cu0 and surface Zn(1+δ)+–OV–Zn(1+δ)+ were pivotal in mitigating adverse impacts of water. Specifically, the enhanced localization of the d-orbitals for Cu+ sites diminished the adsorption capacity of water molecule on Cu+ sites, and surface synergism introduced new active sites for the adsorption and dissociation of ethyl acetate. Their combined effect mitigated the adverse effects of water on catalytic performance at relative low reaction temperature. Among the investigated catalysts, the Cu/SiO2-IZn catalyst, where ZnO was doped through the incipient impregnation method, showed superior hydrogenation performance. It manifested a growth rate of 257.2 %, outperforming the Cu/SiO2 catalyst under optimal reaction conditions with water. In essence, this study makes a substantial contribution to comprehending and refining catalyst design for effective hydrogenation processes in the presence of water.

Calculation of the Rate Constants of Vacuum Residue Hydrogenation Reactions in the Presence of a Chrysotile/NiTi Nanocatalyst

The paper presents the results of an investigation into the kinetics of catalytic hydrogenation of vacuum residue at temperatures of 380, 400 and 420 °C and different durations, ranging from 30 to 70 min, using a nanocatalyst containing the active metals nickel and titanium supported on chrysotile. It was found that the yield of oils from 30 to 50 wt.% and tars from 12 to 18 wt.% increased with increasing temperatures and reaction times. A slight increase in the proportion of solids in the range of 2.0 to 6.0 wt.% is explained by the activity of the nanocatalyst used. In the study of the kinetics of vacuum residue hydrogenation, using the nanocatalyst developed by the authors, we were able to achieve a low yield of solids with a short contact time as well as a high yield of low-molecular-weight compounds such as oils and tars. To determine the kinetic parameters (rate constants and activation energies), Simpson’s integral method and a random search engine optimization method were used. High values of rate constants are characteristic of reactions in the formation of oils k1, tars k2 and asphaltenes k3 in the temperature range of 380–420 °C. The high values of the rate constants k1, k2 and k3 in the catalytic hydrogenation of the vacuum residue indicate the high reaction rate and activity of the nanocatalyst used. With an increase in temperature from 380 to 420 °C, the rate constant of the formation of gas products from vacuum residue and the conversion of asphaltenes into oils significantly increase, which indicates the accumulation of low-molecular-weight compounds in oils. The activation energy for reactions leading to the formation of oils, tars, asphaltenes, gas and solid products was 75.7, 124.8, 40.7, 205.4 and 57.2 kJ/mol, respectively. These data indicate that the processes of vacuum residue hydrogenation with the formation of oils and asphaltenes require the lowest energy inputs. Reducing the process temperature to increase the selectivity of the vacuum residue hydrogenation process when using the prepared nanocatalyst is recommended. The formation of oils at the initial stage plays a key role in the technology of the heavy hydrocarbon feedstock (HHF) hydrogenation process. Perhaps the resulting oils can serve as an additional solvent for high-molecular-weight products such as asphaltenes, as evidenced by the low activation energy of the process.

Unraveling the mechanistic interplay between CO and CO2 hydrogenation over Ni, Co, and NiCo catalysts

Although CO and CO2 hydrogenation reactions have been extensively studied, there is still significant controversy regarding the mechanism of methane formation and the routes for byproducts, especially when both carbon sources are simultaneously present. This work combines kinetic, operando-spectroscopic, isotopic techniques and DFT calculations to elucidate the relationships between CO and CO2 hydrogenation over mono Ni, Co and bimetallic NiCo catalysts with similar metal dispersion. The bimetallic catalysts showed a slight synergistic effect for methane formation from CO, while from CO2 the effect was opposite, showing a negative shift of activity as compared with those observed on the monometallic catalysts. The kinetic analysis shows similar apparent order with respect to H2 (∼0.5) and an inverse secondary isotope kinetic effect (<1) for both methanation reactions, suggesting that CH4 formation proceeds via C-O bond breaking in an H*-assisted mechanism, where the rate-determining step was not shown to be sensitive to the carbon source. The anti-synergistic effect observed on the bimetallic catalysts during CO2 hydrogenation is explained by the formation of unreactive HCOO* species (spectator), which generate a lower density of methane intermediates. On the other hand, the formation of the undesired products, i.e., CO or CO2 during CO2 or CO hydrogenation, respectively, shows relevant differences since the CO formation during CO2 hydrogenation proceeds through the desorption of the carbonyl species adsorbed on weak sites, meanwhile the CO2 formation from CO hydrogenation is due to a minority route of direct dissociation of CO, allowing the rejection of O* with CO* to produce CO2. This study contributes to elucidate the routes that determine the selectivity and reactivity for CO and CO2 hydrogenation and their mechanistic relationship. This information is valuable for the rational design and development of new materials with high performance during hydrogenation processes.

System design and analysis of thermal power dispatch systems for boiling water reactors

Nuclear power plants are crucial to meeting net zero emission goals and achieving energy sustainability. Integrating these plants with clean energy technologies such as high-temperature steam electrolysis (HTSE) may improve the efficiency and economic competitiveness of these plants. The current study investigates the design and operation of a thermal power dispatch (TPD) system for coupling boiling water reactors (BWRs) to HTSE plants. The TPD system extracts a portion of the steam from the reactor’s main steam line and transfers its thermal energy to an HTSE plant through a power transport loop. A TPD system for 5 % steam extraction has been designed and the system performance during steady and transient operations has been analyzed. The TPD system dispatched a total of 197 MW thermal energy to the HTSE plant under nominal design conditions. Saturated steam at 7.17 MPa from the BWR plant was condensed and subcooled to a temperature of 168 °C, while a mass flow rate of 91.1 kg/s of superheated steam was dispatched to the HTSE plant. Furthermore, the system performance during transient operation showed a continuous transition from the initial hot standby mode to the nominal power dispatch level. The transient simulation results emphasized the importance of investigating component level performance for the TPD system design. The current results will guide future works on the development of integrated energy systems for hydrogen production or process heat applications.

Green Synthesis of Diphenyl-Substituted Alcohols Via Radical Coupling of Aromatic Alcohols Under Transition-Metal-Free Conditions.

Alcohols are common alkylating agents and starting materials alternative to harmful alkyl halides. In this study, a simple, benign and efficient pathway was developed to synthesize 1,3-diphenylpropan-1-ols via the β-alkylation of 1-phenylethanol with benzyl alcohols. Unlike conventional borrowing hydrogen processes in which alcohols were activated by transition-metal catalyzed dehydrogenation, in this work, t-BuONa was suggested to be a dual-role reagent, namely, both base and radical initiator, for the radical coupling of aromatic alcohols. The cross-coupling reaction readily proceeded under transition metal-free conditions and an inert atmosphere, affording 1,3-diphenylpropan-1-ol with an excellent yield. A good functional group tolerance in benzyl alcohols was observed, leading to the production of various phenyl-substituted propan-1-ol derivatives in moderate-to-good yields. The mechanistic studies proposed that the reaction could involve the formation of reactive radical anions by base-mediated deprotonation and single electron transfer.

Dynamics of pH Oscillators in Continuous Stirred Tanks in Series.

Complex reaction networks with positive and negative feedback can produce diverse nonlinear phenomena in open reactors, such as multistability and oscillations. pH oscillators driven by hydrogen or hydroxide autocatalytic processes show sustained oscillations in continuously stirred tank reactors (CSTR) but only a sharp pH switch in batch. Here, we present a numerical study on the dynamics of pH oscillators in a series of CSTRs. We show a critical residence time under which bistability and above which oscillations develop. The dynamics of the CSTR cascade show the cross-shaped phase diagram of nonlinear activatory inhibitory systems. In the domain of oscillations, one reactor starts to oscillate autonomously and induces forced complex oscillations in the following tanks with damped amplitudes. These results, with their practical implications, may contribute to understanding the recent experimental observations of nonlinear phenomena in the presence of a residence time ramp and inspire further research in this area.

Increasing of efficiency of hydrogen energy storage system by the use of high-pressure electrolyser with metal hydride electrode

The article describes the electrochemical process of hydrogen and oxygen generation by a membrane-less electrolyser having a passive electrode made of Ni and a gas absorption electrode made of metal hydride (LaNi5Hx). Such composition of the electrode stack materials (Ni - LaNi5Hx) makes it possible to generate hydrogen and oxygen during the half-cycles separately in time while maintaining the time intervals of the corresponding half-cycles. The last one indicates the stable capacitive characteristics of the LaNi5Hx metal hydride electrode. During the oxygen half-cycle, hydrogen is absorbed in the metal hydride electrode while oxygen is released at the nickel electrode and then removed into the oxygen storage system. During the subsequent half-cycle, the hydrogen absorbed by the metal hydride electrode is removed into the hydrogen storage system. We have studied the above electrolysis process with help of the laboratory experimental membrane-less electrolyser giving the possibility for generating, storing and compressing hydrogen in it. The use of a chemically active LaNi5Hx electrode will make it possible to implement a hydrogen energy storage system (electrolyser-storage system-consumer) and accordingly to increase the efficiency of the power plant by ≈ 8–10 %. It would be effective to use such high-pressure membrane-less electrolyser as an energy storage system element of an energy complex that receives electricity from the renewable energy sources (sun, wind).

The Support and Bimetallic Synergy Effects in Cu‐Ni/SiO2 Catalysts for Hydrogenation of Furfural

AbstractHerein, a series of Cu, Ni catalysts were synthesized using mesoporous SiO2 (MCM‐41) and fumed SiO2 as supports for the catalytic hydrogenation of furfural (FF). The MCM‐41 support facilitated the high dispersion of Cu, Ni nanoparticles (NPs), and the hydrogenation products are primarily in the form of alcohols. For fumed SiO2, the proper amounts of acid sites contributed to the better selectivity of 2‐methyltetrahydrofuran(2‐MTHF). Hydrogenation results showed that the 10Cu10Ni/MCM‐41 catalyst afforded a 93.6 % yield of tetrahydrofurfuryl alcohol (THFA), while the 10Cu10Ni/SiO2 catalyst afforded a 61.73 % yield of 2‐MTHF and a 31.63 % yield of THFA. Meanwhile, it is also found that impregnating nickel salt before copper salt is more likely to promote the formation of deep hydrogenation products. Cyclic experiments indicate that developing a one‐step hydrogenation process with selective production of fully hydrogenated products is still a daunting and challenging task.

The electrocatalytic reduction of nitrate to ammonia (NARR) using MOF-808 enhanced by the transition metal Fe (III) and H2PO4−/HPO42−

The combustion of fossil fuels has led to a surge in global CO2 emissions, causing environmental pollution and climate change issues that cannot be ignored. Ammonia, a green and carbon-free hydrogen energy, is emerging as a promising contender for new renewable fuels. Electrocatalytic nitrate-to-ammonia reduction reaction (NARR) is an emerging green synthesis method compared to the Haber-Bosch approach, and its performance is mainly controlled by selective hydrogenation. In this work, we report an efficient Fe@MOF-808-H2PO4−/HPO42− electrocatalyst (donated as Fe@MOF-808-P) for the electrocatalytic reduction of nitrate-to-ammonia. The results showed that the highest Faraday efficiency of NH3 (FENH3) is 90.8 ± 0.5 % at −0.9 V versus reversible hydrogen electrode (vs. RHE) in a 0.5 M potassium sulfate (K2SO4) solution containing nitrite (NO3−), the corresponding NH3 yield and specific activity are 420.4 ± 18.1 μmol h−1 cm−2 and 1035.9 ± 20.1 mgNH3 h−1 mgFe, respectively.Furthermore, a comparative analysis of the catalytic performance of Fe@MOF-808-H2O, MOF-808, MOF-808-P, and carbon cloth (CC) revealed that introducing P could accelerate the hydrogenation process of NO3− in the NARR process, confirming that Fe is the primary active center. Additionally, the cyclic electrolysis experiment demonstrated that the catalyst showed excellent stability. The results highlighted the promising potential of ammonia for future applications in renewable energy systems.

Cu-Fe bimetallic MOFs with long lifetime separated-state charge for enhancing selectivity for CO2 photoreduction to CH4

Improving the CO2 to CH4 conversion efficiency of Cu metal-organic frameworks (Cu-MOFs) catalysts is important for promoting carbon capture and utilization. In this work, a series of novel Cu-Fe bimetallic MOFs photocatalysts (Cu-BTB-Fe with 0.5 wt%, 1.0 wt%, 2.0 wt%, and 4.0 wt% of Fe; H3BTB = 1,3,5-tris(4-carboxyphenyl) benzene) were synthesized by a bimetallic site (Cu and Fe) design strategy in order to improve the electron-hole separation efficiency and CO2 adsorption activation. Findings indicated that the as-synthesized Cu-BTB-2 wt% Fe catalyst exhibited excellent catalytic performance for the conversion of CO2 to CH4 and CO under simulated sunlight irradiation, providing a yield of 32.20 μmol∙g−1∙h−1 and a selectivity of 69.24 % for CO2 to CH4 conversion as well as a yield of 14.29 μmol∙g−1∙h−1 for CO2 to CO conversion without liquid phase products. This is because the Cu-Fe bimetallic sites can continuously supply photoinduced electrons with long separated-state decay lifetime to efficiently activate CO2. Specifically, the Cu-BTB-Fe catalysts provided a high proportion of effective photoinduced electrons with long decay lifetime for the CO* hydrogenation process through a unique electron transfer mechanism, while the strong affinity between CO2 and [Cu2(COO)4]-Fe active units enabled high CO2 adsorption activation and rapid CO2 reduction. The present approach, hopefully, would help to establish feasible pathway for the development of novel highly selective Cu-based MOFs photocatalysts for CO2 photocatalytic reduction yielding CH4.

General synthesis of high-entropy single-atom nanocages for electrosynthesis of ammonia from nitrate

Given the growing emphasis on energy efficiency, environmental sustainability, and agricultural demand, there’s a pressing need for decentralized and scalable ammonia production. Converting nitrate ions electrochemically, which are commonly found in industrial wastewater and polluted groundwater, into ammonia offers a viable approach for both wastewater treatment and ammonia production yet limited by low producibility and scalability. Here we report a versatile and scalable solution-phase synthesis of high-entropy single-atom nanocages (HESA NCs) in which Fe and other five metals-Co, Cu, Zn, Cd, and In-are isolated via cyano-bridges and coordinated with C and N, respectively. Incorporating and isolating the five metals into the matrix of Fe resulted in Fe-C5 active sites with a minimized symmetry of lattice as well as facilitated water dissociation and thus hydrogenation process. As a result, the Fe-HESA NCs exhibited a high selectivity toward NH3 from the electrocatalytic reduction of nitrate with a Faradaic efficiency of 93.4% while maintaining a high yield rate of 81.4 mg h−1 mg−1.

Biomass-to-Green Hydrogen: A Review of Techno-Economic-Enviro Assessment of Various Production Methods

H2 is considered a practical substitute for fossil fuels, especially for transportation by road and air, created either from fossil fuels or through the process of electrolysis of water. Research questions were included based on numerous research and the analysis of articles. The cost analysis of H2 processes, techno-economic hurdles in commercialization, and the economic comparison of various H2-production methods were the basis for the study of papers. The current research examines the different methods of thermochemical, biological, and electrochemical processes utilized in converting biomass into hydrogen. The benefits, constraints, and significant enhancements of every procedure are outlined. The examination assesses the cost of production, the level of technology readiness, and the potential for scalability. Thermochemical techniques, such as gasification and steam reforming, are effective at producing hydrogen. Steam gasification is perfect for moist and dry biomass in the absence of an oxidizing agent. Dark fermentation is more efficient for biological conversion because it requires less energy. Moreover, the electrochemical procedure is viable for biomass. Thermochemical treatment is significantly more advanced than biological or electrochemical treatment when it comes to scaling opportunities based on comparisons of current processes. The results of this research show that biomass–hydrogen processes have the potential for increasing H2 production, but further enhancements are needed to produce larger quantities for competitiveness.

Electrocatalytic Upgrading of Biomass-Derived Compounds for Biofuel Production

Biomass fast pyrolysis liquid (also known as bio-oil) is considered to be one of the most promising renewable carbon feedstocks. However, fresh pyrolyzed bio-oil is acidic and corrosive and contains large amounts of carbonyl and phenolic compounds produced by polymerization under acidic conditions. This work primarily utilizes an electrochemical conversion strategy using only earth-abundant metal catalysts to achieve the carbonyl hydrogenation process. The results show that upgrading this process produces biofuels with greater stability and higher specific energy. In addition to analyzing the chemical implications of this conversion strategy, this work will also discuss why electrocatalytic conversion is a promising technology path for biofuels and fine chemicals. Reference Huang, S., Lam, C. H.* et al. (2022). "The Structural Phase Effect of MoS2 in Controlling the Reaction Selectivity between Electrocatalytic Hydrogenation and Dimerization of Furfural." ACS Catalysis 12(18): 11340-11354.Huang, S., Lam, C. H.* et al. (2022). "MoS2-Catalyzed Selective Electrocatalytic Hydrogenation of Aromatic Aldehydes in an Aqueous Environment." Green Chemistry.Tu, Q., Lam, C. H.* et al. (2021). "Electrocatalysis for Chemical and Fuel Production: Investigating Climate Change Mitigation Potential and Economic Feasibility." Environmental Science & Technology 55(5): 3240-3249.Garedew, M., Lam, C. H.* et al. (2020). "Greener Routes to Biomass Waste Valorization: Lignin Transformation Through Electrocatalysis for Renewable Chemicals and Fuels Production." ChemSusChem 13(17): 4214-4237. Lam, C. H., et al. (2017). "Towards sustainable hydrocarbon fuels with biomass fast pyrolysis oil and electrocatalytic upgrading." Sustainable Energy & Fuels 1(2): 258-266. Figure 1

Base‐Catalyzed Domino Isomerization/Oxidant‐Free Dehydrogenative Annulation of Allylic Alcohols: Scope, Mechanism, and Application

AbstractA domino reaction comprising four consecutive steps based on the strategy of isomerization of allylic alcohols was developed. This base‐catalyzed protocol provided an approach for constructing polysubstituted quinolines without additional additives. A wide range of di‐ or trisubstituted γ‐aminoaryl allylic alcohols bearing alkyl or (hetero)aryl substituents were transformed to a range of structurally diverse quinolines. The utility of this transformation was demonstrated by the application in the concise synthesis of several polysubstituted quinoline derivatives, including natural products and pharmacological agents. Preliminary mechanistic experiments suggest that the isomerization of γ‐aminoaryl allylic alcohol proceeds via an intramolecular 1,3‐hydrogen shift whereas for the aromatization of the dihydroquinoline intermediate two possible pathways exist: acceptorless dehydrogenation and transfer hydrogenation.

Promoting the OH cycle on an activated dynamic interface for electrocatalytic ammonia synthesis

Renewable-driven electrocatalytic nitrate conversion offers a promising alternative to alleviate nitrate pollution and simultaneously harvest green ammonia. However, due to the complex proton-electron transfer processes, the reaction mechanism remains elusive, thereby limiting energy efficiency. Here, we adopt Ni(OH)₂ as a model catalyst to investigate the dynamic evolution of the reaction interface. A proposed OH cycle mechanism involves the formation of a locally OH-enriched microenvironment to promote the hydrogenation process, which is identified through in-situ spectroscopy and isotopic labelling. By further activating the dynamic state through the implementation of surface vacancies via plasma, we achieve a high Faradaic efficiency of almost 100%. The activated interface accelerates the OH cycle by enhancing dehydroxylation, water dissociation, and OH adsorption, thereby promoting nitrate electroreduction and inhibiting hydrogen evolution. We anticipate that rational activation of the dynamic interfacial state can facilitate electrocatalytic interface activity and improve reaction efficiency.

Elevating dimethyl oxalate hydrogenation activity over core–shell Cu/SiO2@CeO2 catalysts

Increasing dimethyl oxalate (DMO) hydrogenation activity remains a challenge. A Cu catalyst was designed by creating Cu nanoparticles (NPs) over SiO2 layer formed on the CeO2 particles (SiO2@CeO2) using the ammonia evaporation method followed by the calcination and reduction step. The optimized 30Cu/SiO2@5CeO2 catalyst shows good performance in the micro-packed bed reactor (100 % DMO conversion, 95.9 % ethylene glycol (EG) selectivity, 200 h stability) under the condition of the ratio of H2 to DMO (H2/DMO) = 30, 190 °C and 2 MPa in the run, and CeO2 was proved to be effective in the DMO hydrogenation process. The exposed CeO2 on the surface of catalyst was found to facilitate the formation of Cu+ by its interaction between adjacent Cu nanoparticles, resulting in the faster adsorption and dissociation of C=O bond on the catalyst surface, according to the characterization results obtained by the XRD, XPS and in situ FT-IR, etc.