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The catalytic hydrogenation of quinoline to decahydroquinoline (DHQ) formation is studied for various parameters such as temperature, hydrogen pressure, reaction time, solvents, reactant-to-solvent ratio, and catalyst loading over 5%Pd loaded on alumina (Pd/Al 2 O 3) to obtain optimal reaction conditions. The hydrogen uptake of quinoline in the liquid phase reaction using isopropylalcohol (IPA) is studied in an autoclave reactor. The optimum reaction parameters of 50 bar H 2 pressure and 175oC with reactant to solvent ratio of 1:9 for reaction time of 5 h are observed. The effect of IPA solvent showed that hydrogen uptake of 6.91 wt% with complete hydrogenation of quinoline and DHQ yield of more than 99% is observed. The reaction kinetic model is developed for a simplified reaction mechanism and is simulated using the Markov Chain Monte Carlo (MCMC) simulation tool to predict the rate constants and the experimental observations are validated with the model predictions. The activation energy for quinoline hydrogenation to py-THQ formation is estimated to be 136.57 kJ/mol. It is envisaged that quinoline hydrogenation to pz-THQ is the rate-limiting step in the DHQ formation. [Display omitted] • Liquid organic hydrogen carrier (LOHC) as a sustainable energy storage solution. • Complete catalytic hydrogenation of quinoline to decahydroquinoline (DHQ). • A simpified reaction mechanism proposed for quinoline to DHQ formation. • Quinoline hydrogen uptake of 6.91 wt % is obtained using IPA solvent. [ABSTRACT FROM AUTHOR]

Solar-driven CO 2 hydrogenation reactions are an attractive approach for the production of chemicals in the CO 2 utilization. We emphasize the importance of reliable temperature measurements for assessing catalyst performance and report the effect of uneven temperature distribution on the product selectivity of the CO 2 hydrogenation reaction of Ru/TiO 2 catalysts, as well as the CO 2 hydrogenation reaction of Ru/TiO 2 catalysts in dark and under UV, visible IR, and full-spectrum light conditions. Full-spectrum utilization exhibits higher activity at the same temperature. In situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) and density functional theory (DFT) calculations clarify the reaction pathway of CO 2 hydrogenation to methane, revealing that UV and visible infrared light promote the adsorption and activation processes at different stages along the chemical reaction pathway, respectively. These findings can facilitate additional innovative ideas for the mechanism study and future development of next-generation photothermal catalysts based on full-spectrum utilization. • Uncovering the misclassification of product selectivity due to heterogeneous temperature distribution on the catalyst. • Revealing the mechanism of action of different spectral light on the CO 2 hydrogenation reaction on Ru/TiO 2 catalysts. • This work provides a rigorous means of measuring catalyst temperature. [ABSTRACT FROM AUTHOR]

The utilization of liquid organic hydrogen carrier (LOHC) based on acetophenone has been considered a promising approach for high energy density hydrogen storage, but its industrial application is limited by the low reaction and mass transfer rates observed in conventional reactors. Microreactors have the potential to promote hydrogen storage technology, and, in this study, we propose a tubular reactor coupled with a gas/liquid microdispersion module. Via generating microbubbles prior to the flow of gas and liquid reactants in the tubular reactor, our designed reactor facilitates enhanced gas/liquid interaction mass transfer, thereby improving hydrogenation reaction characteristics. To evaluate the performance of this intensified trickle bed reactor, we investigated the hydrogenation of acetophenone (AP) to 1-phenylethanolis. The results demonstrate that compared to traditional trickle bed reactors, the designed hydrogenation reactor exhibits superior performance under pressures below 2 MPa, with an absence of byproducts, increased conversion and selectivity of AP, and an achieved hydrogen storage rate reaching 0.095 mol H 2 / g Pd / min. [Display omitted] • An intensified hydrogenation reactor was proposed for efficient hydrogen storage. • A gas/liquid micro-dispersion system has been incorporated into a tubular reactor. • The reaction performance of reactors is evaluated using acetophenone hydrogenation. • The intensified reactor shows a nearly twofold increase in hydrogen storage rate. [ABSTRACT FROM AUTHOR]

• Co0- Coδ+ dual phase nanoparticles with controlled compositions were prepared by modifying support nature and pre-activation condition. • Support nature strongly affects active species concentration. Alumina enhances Coδ+ sites and magnesia promotes Co0 sites, while MgO-MgAl 2 O 4 forms dual-phase Co0- Coδ+ nanoparticles. • Moderate reduction temperature (400 °C) produced both Coδ+ and Co0 sites with a homogeneous distribution and close proximity favors ethanol selectivity. • 20 mol% Co/MgO-MgAl 2 O 4 catalyst demonstrated a maximum ethanol selectivity of 17.1 % (C mol% basis). Catalytic hydrogenation of CO 2 to ethanol is a promising solution to address the greenhouse gas (GHG) emissions, but many current catalysts face efficiency and cost challenges. Cobalt based catalysts are frequently examined due to their abundance, cost-efficiency, and effectiveness in the reaction, where managing the Co0 to Coδ+ ratio is essential. In this study, we adjusted support nature (Al 2 O 3 , MgO-MgAl 2 O 4 , and MgO) and reduction conditions to optimize this balance of Co0 to Coδ+ sites on the catalyst surface, enhancing ethanol production. The selectivity of ethanol reached 17.9% in a continuous flow fixed bed micro-reactor over 20 mol% Co@MgO-MgAl 2 O 4 (CoMgAl) catalyst at 270 °C and 3.0 MPa, when reduced at 400 °C for 8 h. Characterisation results coupled with activity analysis confirmed that mild reduction condition (400 °C, 10% H 2 balance N 2 , 8 h) with intermediate metal support interaction favoured the generation of partially reduced Co sites (Coδ+ and Co0 sites in single atom) over MgO-MgAl 2 O 4 surface, which promoted ethanol synthesis by coupling of dissociative (CH x *)/non-dissociative (CH x O*) intermediates, as confirmed by density functional theory analysis. Additionally, the CoMgAl, affordably prepared through the coprecipitation method, offers a potential alternative for CO 2 hydrogenation to yield valuable chemicals. [Display omitted] [ABSTRACT FROM AUTHOR]

• Nitrobenzene was completely converted to aniline by using PdO/TiO 2 as catalysts with an ultra-low apparent activation energy. • Active hydrogen species were perceived as dominant species which fully came from NaBH 4. • The initial PdO nanoparticles in PdO/TiO 2 provided the adsorption sites for nitro groups. • The Pd/PdO/TiO 2 would be formed in situ by adding NaBH 4. • The Pd nanoclusters would activate NaBH 4 to generate active hydrogen species to attack the adsorbed nitro groups. The reduction of nitrobenzene to aniline is very important for both pollution control and chemical synthesis. Nevertheless, difficulties still remain in developing a catalytic system having high efficiency and selectivity for the production of aniline. Herein, it was found that PdO nanoparticles highly dispersed on TiO 2 support (PdO/TiO 2) functioned as a highly efficient catalyst for the reduction of nitrobenzene in the presence of NaBH 4. Under favorable conditions, 95% of the added nitrobenzene (1 mmol/L) was reduced within 1 min with an ultra-low apparent activation energy of 10.8 kJ/mol by using 0.5%PdO/TiO 2 as catalysts and 2 mmol/L of NaBH 4 as reductants, and the selectivity to aniline even reached up to 98%. The active hydrogen species were perceived as dominant species during the hydrogenation of nitrobenzene by the results of isotope labeling experiments and ESR spectroscopic. A mechanism was proposed as follows: PdO activates the nitro groups and leads to in-situ generation of Pd, and the generated Pd acts as the reduction sites to produce active hydrogen species. In this catalytic system, nitrobenzene prefers to be adsorbed on the PdO nanoparticles of the PdO/TiO 2 composite. Subsequently, the addition of NaBH 4 results in in-situ generation of a Pd/PdO/TiO 2 composite from the PdO/TiO 2 composite, and the Pd nanoclusters would activate NaBH 4 to generate active hydrogen species to attack the adsorbed nitro groups. This work will open up a new approach for the catalytic transfer hydrogenation of nitrobenzene to aniline in green chemistry. [Display omitted] [ABSTRACT FROM AUTHOR]

The hydrogenation of magnesite to CH 4 and MgO offers a powerful approach for CO 2 direct utilization. To deepen the understanding of the reaction mechanisms, (Mg 5 (CO 3) 4 (OH) 2 (H 2 O) 4 was selected as a model compound to gain insights into carbonate hydrogenation. A novel Ni/Fe/ZrO 2 catalyst with ferromagnetic properties was employed to facilitate the magnetic separation of the catalyst from the solid products. Thermodynamic simulation and experiments were conducted to address key issues such as gas evolution during catalytic hydrogenation, the effects of catalyst on CH 4 selectivity, and the separation of solid products and catalyst. The results indicate that lower temperatures favor CH 4 formation, whereas higher temperatures favor CO formation. Increasing Ni loading can enhance the CH 4 selectivity. With the presence of 10Ni/Fe/ZrO 2 catalyst, 100% CH 4 selectivity can be achieved at 300 °C. Moreover, 10Ni/Fe/ZrO 2 catalyst exhibits high magnetic responsiveness, facilitating the solid separation and the recycle of the catalyst. • A novel route for the hydrogenation of magnesite to produce CH 4 and MgO is proposed. • A ferromagnetic Ni/Fe/ZrO 2 catalyst enables efficient separation of the catalyst and product. • Low temperature favors CH 4 formation, while high temperature favors CO formation. • 100% CH 4 selectivity can be achieved at 300 °C with the presence of 10Ni/Fe/ZrO 2. [ABSTRACT FROM AUTHOR]

Rising levels of carbon dioxide (CO 2) emissions due to human activities exert a substantial adverse effect on the environment. The conversion of CO 2 into methanol (CH 3 OH) through hydrogenation is a promising way to utilize this greenhouse gas, thus maintaining carbon in the cycle. In terms of sustainability, methanol is of particular interest because of its dual utilization potential as a fuel or base material to produce different chemicals. The versatility of the latter allows it to be used directly as a precursor to produce numerous compounds, including dimethyl ether (DME), olefins, formaldehydes, and hydrocarbon fuels. This paper first reviews the latest developments in catalyst design, focusing on the relationship between catalyst structure and performance. In addition, recent advances in understanding the reaction mechanisms, optimizing catalyst architectures, innovating membrane reactors, and reaction conditions have been discussed. This summarizes the strategies for increasing the efficiency of sustainable methanol production with the help of membranes. This study provides an outlook for future research in this field. [Display omitted] • Developing efficient hydrogen conversion is essential for addressing climate change. • Technological improvements in the synthesis of water selective zeolite membranes. • Latest developments in CO 2 hydrogenation using Cu-based catalysts. • Adapting zeolite membranes in catalytic membrane reactors to increase methanol yield. • Challenges and perspectives of CO 2 hydrogenation in the presence of a membrane. [ABSTRACT FROM AUTHOR]

The development of low-cost and safe hydrogen storage systems is a priority when creating new energy sources. Storing hydrogen in chemical compounds in which it occurs naturally is the only alternative. Aromatic hydrocarbons, capable of reversible hydrogenation–dehydrogenation reactions, are of the greatest interest among regenerated hydrogen-containing compounds and can be used for hydrogen storage. Naphthalene, its methyl derivatives and the products of hydrogenation have the high storage density among the aromatic hydrocarbons (up to 7.3 wt%) which make it the extremely perspective as liquid hydrogen storage carriers. Therefore, the synthesis of the compounds with the higher added value (as decalin) is a highly important from scientific point of view. However, for the building up of "ideal" chemical system of hydrogen storage the development of effective catalytic systems with the composition and morphology adopted to the structure of aromatic substrate is highly needed. This review discusses the role of the metal in the catalytic hydrogenation of naphthalene and its derivatives for hydrogen storage. [Display omitted] • Chemical hydrogen storage in liquid organic hydrogen carriers is studied. • The supported metal role in the hydrogenation of naphthalene's is discussed. • The non-noble metal doped with small amounts of noble metal are promising catalysts. [ABSTRACT FROM AUTHOR]

• Ni clusters/nanoparticles were redistributed to form smaller dispersed nickel species during CO2 hydrogenation. • Dispersed nickel species can partially fill mesoporous pores of silica support. • Redistribution lead to a decreasing trend of both CO2 conversion and CH4 selectivity over 1% Ni/SiO2 with reaction progress. • This anti-sintering phenomenon could be related to the presence of H2. The CO 2 catalytic hydrogenation represents a promising approach for gas-phase CO 2 utilization in a direct manner. Due to its excellent hydrogenation ability, nickel has been widely studied and has shown good activities in CO 2 hydrogenation reactions, in addition to its high availability and low price. However, Ni-based catalysts are prone to sintering under elevated temperatures, leading to unstable catalytic performance. In the present study, various characterization techniques were employed to study the structural evolution of Ni/SiO 2 during CO 2 hydrogenation. An anti-sintering phenomenon is observed for both 9% Ni/SiO 2 and 1% Ni/SiO 2 during CO 2 hydrogenation at 400°C. Results revealed that Ni species were re-dispersed into smaller-sized nanoparticles and formed Ni0 active species. While interestingly, this anti-sintering phenomenon leads to distinct outcomes for two catalysts, with a gradual increase in both reactivity and CH 4 selectivity for 9% Ni/SiO 2 presumably due to the formation of abundant surface Ni° from redispersion, while an apparent decreasing trend of CH 4 selectivity for 1% Ni/SiO 2 sample, presumably due to the formation of ultra-small nanoparticles that diffuse and partially filled the mesoporous pores of the silica support over time. Finally, the redispersion phenomenon was found relevant to the H 2 gas in the reaction environment and enhanced as the H 2 concentration increased. This finding is believed to provide in-depth insights into the structural evolution of Ni-based catalysts and product selectivity control in CO 2 hydrogenation reactions. [Display omitted] [ABSTRACT FROM AUTHOR]

Three ferrocene-functionalized Zr-oxo clusters featuring increased nuclearity and regular structural variation were synthesized and treated as outstanding catalysts to achieve high-performance thermocatalytic redox reactions, in which LA-to-γ-valerolactone and phenol-to-quinone conversions can be finished at lower temperature and in shorter time, under the synergistic catalysis of active Zr site and functional ferrocene group. (Color online) [Display omitted] The Zr(IV) ions are easily hydrolyzed to form oxides, which severely limits the discovery of new structures and applications of Zr-based compounds. In this work, three ferrocene (Fc)-functionalized Zr-oxo clusters (ZrOCs), Zr 9 Fc 6 , Zr 10 Fc 6 and Zr 12 Fc 8 were synthesized through inhibiting the hydrolysis of Zr(IV) ions, which show increased nuclearity and regular structural variation. More importantly, these Fc-functionalized ZrOCs were used as heterogeneous catalysts for the transfer hydrogenation of levulinic acid (LA) and phenol oxidation reactions for the first time, and displayed outstanding catalytic activity. In particular, Zr 12 Fc 8 with the largest number of Zr active sites and Fc groups can achieve > 95% yield for LA-to-γ-valerolactone within 4 h (130 °C) and > 98% yield for 2,3,6-trimethylphenol-to-2,3,5-trimethyl- p -benzoquinone within 30 min (80 °C), showing the best catalytic performance. Catalytic characterization combined with theory calculations reveal that in the Fc-functionalized ZrOCs, the Zr active sites could serve as substrate adsorption sites, while the Fc groups could act as hydrogen transfer reagent or Fenton reagent, and thus achieve effectively intramolecular metal–ligand synergistic catalysis. This work develops functionalized ZrOCs as catalysts for thermal-triggered redox reactions. [ABSTRACT FROM AUTHOR]

In this research, a novel biogenic strategy for decoration of silver nanoparticles (Ag NPs) on metal-organic frameworks (MOF) was suggested. The proposed protocol depended upon using of propolis as a green reducing agent for immobilization of Ag NPs on MOF. The XRD and SEM analyses were employed to identify the crystallinity and morphology of the fabricated MOF@Ag material, respectively. The MOF@Ag was utilized as an effective catalyst for the catalytic hydrogenation of 4-nitrophenol as a toxic pollutant using potassium borohydride. 4-Nitrophenol was completely reduced in 50 s, as confirmed by UV-Vis experiments. The relationship between the ln(A t /A 0) and reaction time was found to be linear, indicating that the reduction of 4-nitrophenol with the MOF@Ag nanocatalyst followed a pseudo-first-order kinetic. In addition, the green prepared nanocomposite exhibits consistent catalytic activity for a minimum of five cycles in the hydrogenation of target pollutant. The study also explored the anti-cancer property of the MOF@Ag on the common human colon cancer cell lines (HT-29 and HCT-116). The MTT assay studies on cell viability indicated that the MOF@Ag exhibited notable cytotoxicity versus colon cancer. The MOF@Ag composite fabricated in this study have proven to be efficient in the scopes of water purification and cancer therapy. [Display omitted] • Novel green strategy was proposed for decoration of Ag NPs on porous MOF support. • Remarkable catalytic property towards 4-nitrophenol reduction was obtained using the MOF@Ag. • The fabricated MOF@Ag illustrated a notable anti-cancer property versus colon cancer cell lines. [ABSTRACT FROM AUTHOR]

The catalytic hydrogenation of carbon dioxide (CO 2) to methanol presents a significant opportunity for both mitigating climate change and producing a valuable chemical feedstock. While existing reviews delve into diverse modeling strategies, the role and potential of machine learning (ML) approaches remain largely unexplored. This review addresses the gap by comprehensively exploring the mechanism, workflow, and application of ML models in the methanol production process. The review highlights the significance of ML application in catalytic CO 2 hydrogenation for methanol synthesis, emphasizing process optimization, predicting methanol performance indicators, thermodynamic modeling, reaction kinetics, and assessing catalyst activity. Furthermore, the review delves into cutting-edge approaches like hybrid models, gray-box models, and digital twins, showcasing their potential to revolutionize the methanol production process. This comprehensive review serves as a valuable resource for forthcoming research aimed at optimizing the CO 2 conversion process to efficiently and sustainably produce methanol. [Display omitted] • Machine learning models are extensively employed in catalytic hydrogenation to produce methanol. • This review is dedicated to the analysis and synthesis of these models as well as to their applications. • ML exhibits high accuracy in modeling CO 2 hydrogenation into methanol. • ML models predict key performance indicators of methanol and optimize reaction conditions. • Innovative ML, gray box, digital twin, and Hybrid algorithms leverage vast databases in this domain. [ABSTRACT FROM AUTHOR]

The catalytic hydrogenation of carbon dioxide to methanol represents a promising avenue for global warming alleviation. In the present study, the kinetics of high-pressure methanol synthesis from CO 2 hydrogenation over a Cu/ZnO/Al 2 O 3 catalyst were investigated. This study focused on developing a robust kinetic model based on a competitive single-active site Langmuir−Hinshelwood−Hougen−Watson (LHHW) mechanism and utilizing the model to investigate the influence of various operating conditions on the catalytic fixed-bed reactor performance, including temperature, total reactor pressure, feed composition, and gas hourly space velocity (GHSV). The model satisfied the physicochemical constraints to be thermodynamically consistent, and its prediction results of molar flow rates showed a satisfactory correlation of 99% with experimental data available in the literature. The kinetic modeling results revealed that the overall rate of methanol synthesis is inhibited by the surface concentration of formate. Furthermore, adsorbed H 2 and CO 2 were identified as the most abundant intermediates, constituting approximately 80% and 10% of surface coverage throughout the catalytic bed, respectively. According to the present model, relatively mild temperature and pressure ranges of 200–220 °C and 80–100 bar were deemed the optimal operating conditions for enhanced catalytic activity and selectivity towards methanol. These findings not only provide valuable insights into the chemical kinetics of CO 2 hydrogenation to methanol but also enable reliable catalytic reactor designs. [Display omitted] • A detailed chemical kinetics study of methanol synthesis over Cu/ZnO/Al 2 O 3 catalyst. • A robust competitive adsorption kinetic model proposed under industrial conditions. • 99% correlation obtained between model predictions and experimental data. • Adsorbed H 2 and CO 2 identified as the dominant reaction intermediates. • Model indicated a slower methanol synthesis rate than RWGS at T > 275 °C and P < 80 bar. [ABSTRACT FROM AUTHOR]

In the reaction system with NaBH 4 as a hydrogen donor, inhibiting the formation of hydrogen is the key to promote the efficient catalytic hydrogenation of CO 2. In this study, nanoscale zero-valent nickel supported on carbon nanofibers (Ni0/CNFs) was fabricated as a catalyst for CO 2 hydrogenation in aqueous NaBH 4 solution. The characteristics of Ni0/CNFs were examined. By SEM, it was observed that spherical nickel nanoparticles were distributed homogeneously on the surface of strip-shaped carbon nanofibers. EDS mappings indicated that elements were evenly distributed on the catalyst, which might contribute to the uniform exposure of active sites. Via XRD, it was determined that all the diffraction peaks corresponded to the crystal face of nickel metal and that the absence of diffraction peaks of carbon nanofibers indicated that the crystallinity of the carrier was low. XPS study showed that nickel existed on the catalyst surface in two forms: zero valence metal and oxidation state. The effects of catalyst addition amount, NaBH 4 concentration, NaOH dosage, stirring rate on the yield of formate and hydrogen generation rate (HGR) were investigated. By optimizing the above parameters, the concentration of formate reached 150 mmol/L and the hydrogen production rate was 10.55 mL/min. Compared with the non-catalytic conditions, the concentration of formate increased by 57 % and the HGR decreased by 78 %. Moreover, the relationship between CO 2 hydrogenation and NaBH 4 hydrolysis was clarified. This research could enhance comprehension of CO 2 hydrogenation in aqueous NaBH 4 solution and contribute to the development of CO 2 capture and utilization storage technology. The significance of this study lies in clarifying the connection between CO 2 hydrogenation and borohydride hydrolysis in CO 2 catalytic hydrogenation technology. • Ni0/CNFs promoted CO 2 catalytic hydrogenation by inhibiting NaBH 4 hydrolysis. • The relationship between CO 2 hydrogenation and NaBH 4 hydrolysis was clarified. • Catalytic hydrogenation of CO 2 was performed under ambient conditions. [ABSTRACT FROM AUTHOR]

Activated carbons doped with nitrogen and/or sulfur have been obtained by pyrolysis followed of steam activation of a sulfur containing polymer (polythiophene) and two nitrogen-containing polymers (polyaniline and polypyrrole). These polymers were synthesized by oxidative chemical polymerization in aqueous media of their corresponding monomers. The influence of the steam activation on the textural properties and surface chemistry of the carbons has been evaluated and their catalytic activity has been determined in the hydrogenation reaction of 1-chloro-4-nitrobenzene. The degree of conversion in the reaction depends on the development of adequate porosity in the activated carbon (which is determined by the activation conditions) together with the presence of heteroatoms that act as active catalytic sites, with S showing considerably greater effectiveness than N. A compromise between an acceptable level of doping with sulfur and an adequate porosity is necessary, which has been achieved in a carbon obtained from polythiophene pyrolyzed at 900 °C and steam activated at 800 °C for 4 h, with a specific surface area of 742 m2/g and S content of 1.71 at%. [Display omitted] • N and S containing polymers used as precursors of metal-free doped activated carbons. • S-doped carbons are more active than N-doped carbons in the catalytic hydrogenation of 1-chloro-4-nitrobenzene. • Steam activation at high temperature develops carbon porosity but removes heteroatoms. • Compromise between S-doping and developed porosity is necessary to maximize catalytic performance. • 100 % selectivity in the hydrogenation of the nitro group towards aniline in all cases. [ABSTRACT FROM AUTHOR]

The benzyltoluene (H0-BT)/perhydro benzyltoluene (H12-BT) LOHC system is very attractive for large-scale hydrogen storage and transportation applications due to its fuel-like handling and excellent technical availability. H0-BT is applied in industrial quantities since the 1960′ies as heat trafer fluid and is technically produced by a Friedel-Crafts alkylation of chlorobenzene and toluene. However, the current production route leads to minor impurities of chloroorganic compounds in technical H0-BT that were found to severely harm the performance in the catalytic hydrogenation to H12-BT, i.e. in the hydrogen charging process of the respective LOHC storage cycle. Our contribution deals with three aspects of this practically highly relevant topic: a) It discloses the previously unknown chemical structure of the relevant chloroorganic impurities; b) it develops a process for their removal by adsorption and/or hydrodechlorination using a commercial Ni/SiO 2 –Al 2 O 3 material, and c) it determines the performance difference of the so-purified H0-BT samples and H0-BT samples containing the relevant chloroorganic compounds in the catalytic hydrogenation of H0-BT to H12-BT. [Display omitted] • Chlororganic impurities are relevant in technical benzyltoluene. • They cause significant deactivation in catalytic hydrogenation. • Adsorption and hydrodechlorination are suitable methods for removal. • Purified benzyltoluene shows better performance as LOHC compound. [ABSTRACT FROM AUTHOR]

The selective hydrogenation of nitroarenes to their corresponding anilines is one of the most important transformation in environmental protection and fine chemicals production community since the nitro compounds are hazardous to environment and human health, as well as the functionalized anilines are industrially significant. Catalytic transfer hydrogenation (CTH) using an in-situ provided hydrogen donor has received considerable attention as an alternative to the traditional high-pressure hydrogenation process due to the merits of high efficiency, atomic economy and sustainability. However, the complicated elemental reaction network and the strict prerequisite are required to link the two successive reactions between the hydrogen evolution and subsequent hydrogenation. In this review, the designing and regulating strategies of synergistic (metallic) catalysts for CTH of nitroarenes were systematically summarized, which were based on the purpose to pursue a satisfactory catalytic efficiency and chemoselectivity to the terminal target. To provide in-depth recognition and understanding the role of functional sites in catalytic reduction of nitroarenes, herein this review presented the state-of-the-art of tandem catalysis, the proposed mechanisms for hydrogenation of nitroarenes with or without CTH, more importantly, the latest design strategies and cooperation effects of novel functional synergistic heterostructure catalysts of CTH of nitroarenes. The perspectives may contribute to the development of the fundamental theoretical framework of synergistic catalysts-driven CTH reactions. In this review, the designing and regulating strategies of synergistic (metallic) catalysts for CTH of nitroarenes were systematically summarized, which were based on the purpose to pursue a satisfactory catalytic efficiency and chemoselectivity to the terminal target. [Display omitted] [ABSTRACT FROM AUTHOR]

Sodium phenoxide is considered as one of the potentially promising hydrogen storage materials due to its high hydrogen capacity and enhanced thermodynamic properties. However, efficient catalysts are needed to overcome kinetic barriers of the hydrogenation and dehydrogenation processes. In the present work, an ultrafine amorphous Ru–B alloy catalyst was synthesized by a solid-phase ball milling of RuCl 3 with NaBH 4 and subsequently tested for the hydrogenation of sodium phenoxide in an aqueous solution at room temperature. The conversion of phenoxide is significantly improved by 48.9 % on the Ru 3.9 B alloy catalyst compared with pristine Ru nanoparticles. Kinetic studies revealed that the hydrogenation of sodium phenoxide is of first-order with respect to H 2 pressure and zero-order to the concentration of sodium phenoxide over the Ru 3.9 B catalyst. Characterizations showed that the electronic structure of Ru is well modulated by B, leading to an electron-rich state of Ru. The highly active catalysis may be due to the fine dispersion, amorphous state, and electron-rich state of Ru in the ultrafine alloy. [Display omitted] • Amorphous Ru–B alloy was synthesized without any supports or protecting agents. • Room temperature hydrogenation of phenoxide was achieved over Ru–B alloy catalyst. • The electron-rich state structure of Ru is well modulated by B. • The amorphous nature and unique electronic structure lead to outstanding activity. [ABSTRACT FROM AUTHOR]

Catalytic transfer hydrogenation has attracted great interest as a safe and green method to achieve biomass-based hydrogenation. In this study, a NiZr1/CoOx-400 catalyst was fabricated by in-situ structure topological transformation of layered double hydroxides (LDHs) precursors, which exhibited excellent performance in the in-situ hydrogenation of furfural (FF) using isopropanol as the hydrogen donor, with a maximum FF conversion of 83.5% in only 2 h. According to XRD, XPS and H 2 -TPR analyses, there was a strong interaction between different metal species in NiZr/CoOx, which increased the surface charge heterogeneity and promoted the phase transition of metal oxides, thereby favoring the generation of oxygen vacancies. Among them, LDHs structure of NiZr1/CoOx-400 catalyst was conducive to expose oxygen vacancies, which could facilitate its interaction with FF. And the Co in the catalyst similarly promoted the adsorption of FF through the coordination of the catalyst surface with the –CHO group in FF, thus contributing to its conversion. The electron-rich Zr repelled the furan ring and prevented the excessive hydrogenation, which improved its selectivity. In addition, the FF hydrogenation followed the quasi-primary kinetics with a low apparent activation energy of 18.4 kJ/mol, which was comparable to that of noble metal catalysts. [Display omitted] • The NiZr/CoOx surface presented abundant oxophilic Co and oxygen vacancies. • A high FF conversion of 83.5% was obtained in only 2 h. • The activation energy of FF hydrogenation was as low as 18.4 kJ mol−1. • The impact of Zr on the selective hydrogenation of FF to FA was revealed. [ABSTRACT FROM AUTHOR]

In this study, TiO 2 was morphologically engineered into three distinct structures, namely three-dimensional microparticles (MPs), zero-dimensional nanoparticles (NPs) and one-dimensional nanowires (NWs) to examine the effect of structure on CO 2 methanation. Firstly, thermodynamic analysis was conducted, whereby it was observed that CH 4 production is favoured at low temperature. Higher temperature will cause the CH 4 selectivity to drop, in turn increasing the formation of other side products such as CO, C 2 H 6 and solid coke. Then, Ni loaded on three different TiO 2 supports, namely 3D TiO 2 microparticles (MPs), 0D nanoparticles (NPs) and 1D nanowires (NWs), were prepared. It was noticed that the NPs have the smallest support particle size, followed by NWs and MPs. Despite TiO 2 NWs having a larger particle size than NPs, the 15% Ni/TiO 2 NWs boasted a higher surface area, smaller NiO crystalline and particle size, which resulted in an augmented NiO dispersion. Superior CO 2 methanation performance with CO 2 conversion, CH 4 yield and selectivity of 88.44%, 87.53% and 98.97%, respectively was achieved over 15% Ni/TiO 2 NWs. The stability of the TiO 2 NWs counterpart over a 40 hours reaction time was the best among the three samples. Spent catalyst analysis also indicated that 15% Ni/TiO 2 NWs are highly resistant to catalyst deactivation and coke formation. The prolonged durability was attributed to the 1D wire-like structure, which promoted a higher dispersion of active sites, facilitating an intimate contact between catalyst and reactants. The ameliorated dispersion also mitigates catalyst deactivation via sintering and coke formation. The findings elucidated that the morphology of the catalyst is more influential in enhancing the hydrogenation reaction than the support size. • Thermodynamic analysis showed that CO 2 methanation is favourable at low temperatures. • TiO 2 was engineered into 3D microparticles, 0D nanoparticles and 1D nanowires. • 15 wt% Ni on 1D TiO 2 NWs has the best activity compared to 3D TiO 2 MPs and 0D NPs. • High stability is achieved where coking and deactivation is suppressed over TiO 2 NWs. • Effect of catalyst morphology is greater than particle size for methanation activity. [ABSTRACT FROM AUTHOR]

To ameliorate the activation performance and absorption/desorption properties, Mg-based composites are prepared via catalytic mechanochemical hydrogenation (CMCH) strategy by TiF 3 or Nb 2 O 5 or both. The results show that multiple H 2 filling mechanochemical hydrogenation (MCH) way is in favour of the transformation from Mg to MgH 2. The hydrogenation process and hydrogenation degree of Mg can be effectively accelerated via CMCH with TiF 3 or Nb 2 O 5 or both. The complete hydrogenation time for CMCH Mg–TiF 3 and Mg–TiF 3 –Nb 2 O 5 is compressed to 12 h, which is much shorter than those of CMCH Mg–Nb 2 O 5 and Mg systems. The hydrogenation capacities at 3rd activation cycle of 12 h CMCH Mg–TiF 3 , Mg–Nb 2 O 5 and Mg–TiF 3 –Nb 2 O 5 are 5.87, 5.74 and 5.38 wt%, which corresponding to 81.3%, 79.5% and 74.5% activation rates. The hydrogenation capacities at 3rd activation cycle of 20 h CMCH Mg–TiF 3 , Mg–Nb 2 O 5 and Mg–TiF 3 –Nb 2 O 5 are 6.56, 7.08 and 7.18 wt% with 90.9%, 98.1% and 99.4% activation rates. The absorption capacities of CMCH Mg–TiF 3 , Mg–Nb 2 O 5 and Mg–TiF 3 –Nb 2 O 5 at 350 °C under 3 MPa pressure within 0.5 h are 5.75, 5.74 and 4.67 wt%. The dehydrogenation peak temperatures of γ-MgH 2 reduce to 367.37 °C and 366.59 °C and the initial desorption temperatures are 355.77 °C and 351.39 °C of 12 h and 20 h CMCH Mg–TiF 3 –Nb 2 O 5 at 5 °C/min heating rate. The lowest dehydrogenation peak temperatures of 391.73 °C and 389.81 °C are achieved by 12 h and 20 h CMCH Mg–TiF 3 –Nb 2 O 5 samples. The catalytic mechanochemical hydrogenation has been proved to be a feasible and effective strategy for fast acquisition of Mg-based hydride composites with expected hydrogen storage performance. • Catalytic mechanochemical hydrogenation (CMCH) is used to synthesize composites. • Mechanochemical hydrogenation of Mg can be greatly reduced to 12 h by CMCH Mg–TiF 3. • 7.18 wt% H 2 and 99.4% activation rate can be achieved by 20 h CMCH Mg–TiF 3 –Nb 2 O 5. • 7.26, 7.05 and 6.62 wt% H 2 can be absorbed by 20 h CMCH Mg–TiF 3 /Nb 2 O 5 /TiF 3 –Nb 2 O 5. • Peak desorption temperature of 389.81 °C are achieved by 20 h CMCH Mg–TiF 3 –Nb 2 O 5. [ABSTRACT FROM AUTHOR]

The catalytic transfer hydrogenation (CTH) reaction has emerged as a safer method for converting biomass derivatives into value-added chemicals. This study aims to comprehensively evaluate two processes for converting furfural into 2-methylfuran (2-MF) using either methanol (or MeOH, Scheme 1) or isopropyl alcohol (or IPA, Scheme 2) as hydrogen carriers. Both processes were rigorously simulated using Aspen Plus. The reaction performance was modeled using kinetic models developed from literature data. In addition, appropriate strategies are first established for separating the reactor effluents of both processes, which contain multiple azeotropes, based on the thermodynamic parameters estimated through COSMO-based calculations. From the techno-economic analysis, the minimum required selling price (MRSP) of 2-MF is 5.15 USD/kg when produced with Scheme 1 , and 3.63 USD/kg when produced with Scheme 2. The MRSP in Scheme 1 becomes 4.50 USD/kg by considering the benefits of the side product, a formalin solution. Compared to various literature data, the MRSPs of these two process schemes are significantly lower than that obtained from direct hydrogenation (6.87 USD/kg). If the cost of the starting materials can be reduced by 25% or more, the MRSP becomes comparable to that obtained from an improved direct hydrogenation process (2.20–3.30 USD/kg). Furthermore, the CO 2 emission analysis reveals that Scheme 2 has a lower rate of indirect CO 2 emission rate (0.926 Ton-CO 2 /Ton-2-MF) compared to Scheme 1 (1.088 Ton-CO 2 /Ton-2-MF). With thorough assessment, we have concluded that the production of 2-MF through the CTH reaction in Scheme 2 is superior. This process shows promise in both economic and decarbonization aspects and could have industrial significance. [Display omitted] [ABSTRACT FROM AUTHOR]

The incorporation of DEB-Pd/C into polymers provides a possible solution to obtain various composite materials with customized properties. In this work, we selected SEBS as a substrate to prepare an ultra-thin flexible DEB-Pd/C@SEBS composite film. The mechanical properties and hydrogen uptake properties of composite films with different DEB-Pd/C contents and different thicknesses were investigated. The results show that these films possess excellent H 2 uptake and mechanical properties. We speculate that the microphase separation structure of these films results in high gas permeability and diffusion rate, which make the material have good compatibility. In addition, these films can be cut and bent into any shape, which can be applied to hetero-slit space easily and conveniently. • The ultrathin flexible hydrogen getter films were fabricated by filling DEB-Pd/C into the SEBS substrate. • The films have good compatibility between DEB-Pd/C and SEBS. • The films have microphase separation structure, which led to high gas permeability and diffusion rate. • The films have excellent H 2 uptake performance and mechanical properties. • The films can be cut into any shape and bent arbitrarily, which can be applied to hetero-slit space. [ABSTRACT FROM AUTHOR]

A molten salt synthesis method was used to prepare high-entropy AlCoCrFeNi alloy powder with a high specific surface area of 67.5 m2/g, exhibiting remarkable catalytic activity in the hydrogenation of p -nitrophenol by NaBH 4. The life cycle assessment of the proposed method indicated that AlCoCrFeNi production was associated with greenhouse gas emission of 125 kgCO 2 e/kg-product, whose main contributors were CaH 2 and citric acid used during the precursor's reduction and formation, respectively. On the other hand, that for a previously reported dealloying method was 277 kg CO 2 e/kg-product. Thus, a minimum of 54% greenhouse gas emission reduction compared to the conventional dealloying method is achievable in the proposed molten salt method. The results indicated the possible environmentally friendly production of high-surface-area, high-entropy alloy powders suitable for industrial applications. [Display omitted] • Molten salt synthesis of high-surface-area, high-entropy AlCoCrFeNi alloy powder (67.5 m2/g). • Greenhouse gas emission of 125 kgCO 2 e/kg-product by life cycle assessment. • 54% greenhouse gas emission reduction compared to a conventional dealloying method. [ABSTRACT FROM AUTHOR]

The treatment methods for heavy metal contaminants at low-concentrations (<10 mg/L) are attracting extensive attention due to the difficulty of degrading and the tendency of causing serious environmental hazards. As a result of the strong chelating ability to various metals, amidoxime structure is applicable in the adsorption of metal ions. Herein, it has been successfully synthesized amidoxime-functionalized acrylamide/amidoxime-chitosan (AM/AO-CS) aerogels as efficient adsorbents for low-concentration metal ions in aqueous solutions. The porous characteristics of chitosan carrier and abundant amidoxime groups make AM/AO-CS aerogels environmentally friendly and well-performing. AM/AO-CS aerogels displayed 97.4 % adsorption ratio of Cu2+ at a concentration of 10 mg/L. The adsorption isotherms of Cu2+ could be fit well by the Langmuir model. Moreover, AM/AO-CS aerogels adsorbed with Cu2+ were further applied as the catalysts in the hydrogenation of p-nitrophenol. [Display omitted] • A green and universal strategy was developed to construct hydrophilic amidoxime-functionalized aerogels. • AM/AO-CS composite aerogels were successfully synthesized for the adsorption of low-concentration Cu2+ aqueous solution. • AM/AO-CS aerogels exhibited remarkable adsorption performance in low-concentration Cu2+ aqueous solution. • Cu-AM/AO-CS aerogels exhibited good catalytic performance on the hydrogenation of p-nitrophenol. [ABSTRACT FROM AUTHOR]

Liquid catalytic hydrogenation is a green, economical and non-polluting technology that can effectively reduce and remove pollutants from water. In this study, Pd/MnO2 catalyst was synthesized with precious metal Pd as the active component and MnO2 as the carrier, and formic acid was used as the hydrogen source for liquid catalytic hydrogenation to reduce Cr(VI); And the composition and morphology of Pd/MnO2 catalyst were characterized by X-ray diffraction, transmission electron microscopy and scanning electron microscopy; in the reaction of Cr(VI) reduction, the effects of different catalysts, catalyst dosage, initial concentration of Cr(VI), pH and different Pd loadings on the reduction of Cr(VI) were investigated. The results of the experimental tests showed that the reduction of Cr(VI) by Pd/MnO2 was 93.2%, the reduction of Cr(VI) by MnO2 was 20.9%, and the reduction of Cr(VI) by MnO2 after loading Pd was 4.46 times higher than that by unloaded Pd. The results of the study showed that the reduction of Cr(VI) by Pd/MnO2 was not significant when the pH was 2, the initial concentration of Cr(VI) was 1 mM, the loading of Pd was 0.74 wt.%, and the catalyst dosage was 0.25 g/L, the Pd/MnO2 catalyst could reduce Cr(VI) in water more rapidly and effectively; the Pd/MnO2 catalyst is a new type of rapid and efficient catalyst for Cr(VI) reduction. [ABSTRACT FROM AUTHOR]

Two-dimensional molybdenum carbide (2D-Mo 2 C) is thought to be promising for catalytic hydrogenation of CO 2 to CH 4 , but little is known about its catalytic reaction mechanism. In this work, we investigate the hydrogenation of CO 2 to CH 4 on 2D-Mo 2 C using density functional theory. Our calculations show that Mo on the surface can efficiently decompose CO 2 to CO and O, and also H 2 to H. The hydrogenation of CO produces CHO that is readily deoxygenated to CH, and CH is selectively hydrogenated to produce CH 4. Interestingly, the embedded Ir 1 on 2D-Mo 2 C can act as a single-atom promoter to improve the performance of CO 2 methanation, while on the other hand maintaining its high selectivity for CH 4. This work provides insight into the mechanism of 2D-Mo 2 C-catalyzed CO 2 methanation reactions and suggests a strategy to improve the performance of such catalysts through single-atom promoters. [Display omitted] • Mechanism for the hydrogenation of CO 2 to CH 4 on 2D-Mo 2 C was studied by DFT. • Mo active sites of 2D-Mo 2 C can effectively dissociate CO 2 to CO and O. • A strategy is proposed to improve the performance of CO 2 methanation on Mo 2 C. [ABSTRACT FROM AUTHOR]

The catalytic transfer hydrogenation (CTH) of bio-oil over CuO/PC (porous carbon) with the solid residue produced during biomass pyrolysis as the carrier was investigated with methanol as the hydrogen donor. The effect of carbonization temperature, activation temperature, KOH solution and metal loading on the physicochemical characteristics of CuO/PC catalystand catalytic transfer hydrogenation of bio-oil were investigated. The main alcohols formed in the CTH of bio-oil were 1, 4-butanediol, 1, 3-cyclopentadiol, 1, 3-cyclohexanediol, 2-cyclohexenol and alcohols. It was revealed that more alcohols were produced over CuO/PC using less Cu(NO 3) 2 than Cu 2 Al considering their favorable porous system. The well-developed pore structure is formed in PC at a higher calcination temperature and the concentration of activator, which was favorable for the CTH of bio-oil. Under the optimized preparation conditions, the mesopores accounting for 50% in the total pores, achieving the maximized yield of alcohols of 81%, and the well recycling performance was observed with the overall yield of alcohols decreases within 3% after five cycles because of the greater mesopores ratio. The biochar-based PC catalyst in this work enhances the effective usage of biomass to produce alcohols, fully conforming to the theme of energy conservation and low-carbon times. [Display omitted] [ABSTRACT FROM AUTHOR]

Efficient catalytic technologies for converting CO 2 with hydrogen into value-added chemicals and fuels can help to solve the environmental problems related with large CO 2 emissions. Among of the most interesting products that can be synthesized from CO 2 are synthetic natural gas, methanol and DME, methane and higher hydrocarbons, higher alcohols. In this mini review, we highlight the recent advances in the development of heterogeneous catalysts and processes for of CO 2 hydrogenation to these products. Recent research to develop highly active and selective catalysts based on controlled synthesis – active phases, promoters, supports, thermodynamics, are presented. [Display omitted] • Hydrogen is efficient reagent for CO 2 transformation into valuable products. • Heterogeneous catalytic hydrogenation is an attractive method of CO 2 processing with hydrogen. • Catalysts for CO 2 hydrogenation are to be active, selective, stable, reusable for high efficiency of the process. [ABSTRACT FROM AUTHOR]

The high and low temperature dual reaction zone RTS (removing trace sulfur) technology is a novel hydrotreating process but lack of in-depth understanding of its kinetics. Three-lump and five-lump kinetic models were developed based on the diesel hydrogenation experimental data which were carried out in the RTS process under various operating conditions to predict the concentrations of ultra-level sulfur and aromatics in hydrotreated oil samples, respectively. Moreover, the inhibiting effect of the hydrogen sulfide (H 2 S) on the hydrodesulfurization rates of S-compounds has been studied by performing calculations with the actual adsorption concentration of H 2 S in the catalytic active center. The proposed models were able to reproduce the RTS process with good adjustment and accuracy, and relative deviations below 10.7 % at sulfur content below 10 ppm and polycyclic aromatics hydrocarbons content below 3 wt%. Therefore, these models can serve as an effective guide for diesel hydrotreatment, and the calculated results indicate that the optimal operating conditions in the 1st and 2nd reactors are 350 °C and 340 °C, respectively, at a constant pressure of 6.4 MPa and H 2 /oil volume ratio of 300 v/v. [ABSTRACT FROM AUTHOR]

[Display omitted] The effective surface concentration of Pd 1 sites composed of individual palladium atoms isolated from each other by Ag atoms in the Pd 1 Ag 10 /Al 2 O 3 single-atom alloy (SAA) catalyst can be significantly enhanced by the adsorption-induced surface segregation upon a special pretreatment of the catalyst in a CO-containing atmosphere at 200 °C. The catalyst activity towards acetylene hydrogenation gets tripled without sacrificing selectivity for ethylene. The segregated surface of the catalyst is thus preserved under target reaction conditions. [ABSTRACT FROM AUTHOR]

The hybrid material composed of palladium nanoparticles (PdNPs) functionalized with N-heterocyclic carbene ligands (NHCs) immobilized onto the surface of reduced graphene oxide (rGO) results in an efficient catalytic material towards hydrogenation and dehydrogenation of N-heterocycles. The rGO plays a dual role by acting as a carbocatalyst in acceptorless dehydrogenation of N-heterocycles and as a support for the palladium nanoparticles facilitating its interaction with molecular hydrogen turning this hybrid material into an effective hydrogenation catalyst. Hot filtration experiments support the heterogeneous nature of the process underlining the strong interaction of palladium nanoparticles with the graphene enabled by π-interactions of the ligand with the support. The mild conditions used in both transformations of this system without requiring any additives facilitates its potential application in hydrogen storage technologies in the form of liquid organic hydrogen carriers (LOHCs). At the same time, the hybrid material is a robust and efficient catalytic platform that can be recovered and reused up to eight runs in both transformations without significant deactivation. The use of a single solid catalysts that is recyclable in hydrogen conversion and reconversion through (de)hydrogenation of N-heterocycles paves the way for the development of efficient hydrogen storage materials. [Display omitted] • An efficient catalytic material for hydrogenation and dehydrogenation of N-heterocycles. • Hydrogen storage in the liquid form using N-heterocycles as liquid organic hydrogen carriers. • Combination into a single material of metal-mediated catalysis by MNPs and carbocatalysis by rGO for a reversible reaction. • A bottom-up approach for the preparation of PdNPs functionalized with NHC ligands immobilized onto rGO. • A selective, reusable and durable catalytic material for (de)hydrogenation of N-heterocycles. [ABSTRACT FROM AUTHOR]

The complex hydride NaAlH 4 remains the archetype hydrogen storage system. In this paper, we have explored the catalytic action of Al 65 Cu 20 Fe 15 quasicrystal (QC) on the de/re-hydrogenation study of NaAlH 4. The leached ball-milled Al 65 Cu 20 Fe 15 (LBMACF) catalyzed NaAlH 4 sample has shown a lower hydrogen desorption temperature (140 °C) than other catalyzed and uncatalyzed NaAlH 4 samples. NaAlH 4 -LBMACF rapidly absorbed ∼3.20 wt% of hydrogen within 1 min and absorbed maximum capacity (∼4.68 wt%) in 15 min, while NaAlH 4 -LACF, NaAlH 4 -BMACF, NaAlH 4 -ACF, and pristine NaAlH 4 absorbed only 0.50 wt%, 1.38 wt%, 1.10 wt%, and 0.70 wt% in 1 min at 130 °C under 100 atm hydrogen pressure. NaAlH 4 -LBMACF has desorbed ∼4.22 wt% of hydrogen within 15 min, while the same amount of hydrogen desorbed by NaAlH 4 -LACF takes 45 min at 130 °C under 1 atm hydrogen pressure. NaAlH 4 -LBMACF shows reversibility up to 25 cycles with minimum degradation of hydrogen storage capacity of ∼0.06 wt% during de/re-hydrogenation. The catalytic mechanism and catalytic effect of Al–Cu–Fe on the NaAlH4 have been discussed using structural, microstructural analysis, in-situ nuclear magnetic resonance (NMR) spectroscopy, in-situ Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS). • Al–Cu–Fe quasicrystal and its modified versions have explored as catalyst. • Mechanistic understanding of catalytic behavior of Al 65 Cu 20 Fe 15 quasicrystal. • NaAlH 4 -LBMACF absorbed ∼3.20 wt% of hydrogen within 1 min and desorbed ∼4.22 wt% of hydrogen within 15 min. • Excellent reversibility and cyclic stability of NaAlH 4 -LBMACF sample up to 25 cycles. [ABSTRACT FROM AUTHOR]

[Display omitted] Development of efficient catalysts with high atomic utilization and turnover frequency (TOF) for H 2 activation in slurry phase hydrocracking (SPHC) is crucial for the conversion of vacuum residue (VR). Herein, for the first time, we reported a robust and stable single atoms (SAs) Mo catalyst through a polymerization-pyrolysis- in situ sulfurization strategy for activating H 2 in SPHC of VR. An interesting atomic coordination structural dynamic evolution of Mo active sites was discovered. During hydrocracking of VR, the O atoms that coordinated with Mo were gradually replaced by S atoms, which led to the O/S exchange process. The coordination structure of the Mo SAs changed from pre-reaction Mo-O 3 S 1 to post-reaction Mo-O 1 S 3 coordination configurations, promoting the efficient homolytic cleavage activation of H 2 into H radical species effectively. The evolved Mo SAs catalyst exhibited robust catalytic hydrogenation activity with the per pass conversion of VR of 65 wt%, product yield of liquid oils of 93 wt%, coke content of only 0.63 wt%, TOF calculated for total metals up to 0.35 s−1, and good cyclic stability. Theoretical calculation reveals that the significant variation of occupied Mo 4d states before and after H 2 interaction has a direct bearing on the dynamic evolution of Mo SAs catalyst structure. The lower d -band center of Mo-O 1 S 3 site indicates that atomic H diffusion is easy, which is conducive to catalytic hydrogenation. The finding of this study is of great significance to the development of high atom economy catalysts for the industrial application of heavy oil upgrading technology. [ABSTRACT FROM AUTHOR]

Hydrogenation of nitriles represents an efficient and environmentally benign route to synthesis of high-value amines. However, the amine selectivity is commonly low, and the mixtures of amines, imines, and even low-value hydrogenolysis byproducts are generally obtained. Herein, we report that overcoating of Pd and Pt catalysts with an ultra-thin NiO x layer via atomic layer deposition enables to close up the undesired hydrogenolysis pathway completely and to prompt a yield of secondary amines drastically to 96% under mild conditions in the hydrogenation of nitriles. The NiO x -coated catalysts also exhibit a much higher recyclability than the uncoated ones. Through detailed structural characterization and control experiments of catalytic performance tests, we show that the NiO x overcoat plays at least three important roles in the promotion of catalytic performance: (i) Enhancement of the adsorption of both imine intermediates and primary amines, to stimulate the subsequent condensation of these two molecules to form secondary amines exclusively with a high activity; (ii) Isolation of large Pd and Pt ensembles to inhibit the hydrogenolysis byproduct; and (iii) Acting as a protective layer to stabilize metal nanoparticles against leaching, and to prevent the formation of undesired metal hydride phase, thus leading to a significant improvement in catalytic stability. These findings provide a robust methodology for directing selective hydrogenation of nitriles to secondary amines exclusively, and the insights here would facilitate the rational design of oxide overcoating layers for advanced catalysis. [Display omitted] • Precise synthesis of ultrathin NiO x overcoats decorated Pd and Pt catalysts via ALD. • Large metal ensembles were divided into tiny aggregates or isolated atoms by NiO x. • NiO x -coated catalysts enabled hydrogenation of nitriles exclusively to secondary amines. • Hydrogenolysis side reaction pathway was completely inhibited by NiO x overcoating. • NiO x overcoats represented as protective layers by which improving the stability. [ABSTRACT FROM AUTHOR]

K-doped FeC x catalysts derived from the carbothermal reduction of the Fe-chitosan complex were investigated and tested in the hydrogenation of CO 2 to light olefins (C 2-6 =). Catalyst characterization, including bulk composition, porosity, crystallinity, Fe coordination, morphology, surface property, and basicity, was conducted. The physicochemical properties of tested catalysts were correlated with their performances. The mechanistic study discovered that bidentate carbonates, monodentate carbonate, bicarbonate, and formate species were intermediates involved in C 2-6 = synthesis. The yield of C 2-6 = was found to be dependent on the composition of the carbide phases of K-doped FeC x catalysts. The most active catalyst, i.e., FeK@CS-(0.5)-py, showed the most promising space-time yield of C 2-6 = (13.7 μmol C2-6= /g Fe /s). [Display omitted] • K-doped FeC x catalysts were derived from the Fe-chitosan complexes. • A proper Fe-to-chitosan is important to increase the FeC x content. • A positive correlation between FeC x and the yield of C 2-6 = olefins was found. • Carbonates and formate were identified as the possible intermediates. [ABSTRACT FROM AUTHOR]

The understanding of intrinsic kinetics was crucial in guiding reactor design. However, the intrinsic kinetics of catalytic hydrogenation of p-nitroanisole (PNA) to p-aminoanisole remains obscure. In this work, the kinetic characteristics were experimentally and theoretically investigated under various experimental conditions. From the power law analysis of the initial reaction rate, the reaction order was found to be from 0.34 (at 343 K) to 0.53 (at 353 K) for hydrogen and 0.31∼ 0.34 for PNA (at concentrations less than 90 g·L−1), while the reaction was considered to be zero-order under higher PNA concentration (>90 g·L−1). The data was also used to fit Eley-Rideal and Langmuir-Hinshelwood-Hougen-Watson (LHHW) models. It was found that the rate-controlling step was the adsorption of dual-site dissociative H 2 based on LHHW model. The accuracy of the screened model was verified by correlation, between the predicted data and experimental data. This study could provide significant guidance for the hydrogenation reaction and reactor. • The intrinsic kinetics of hydrogenation of PNA to PA was experimentally studied. • The parameters of power law rate model were obtained. • The absorption of dual-site dissociative H 2 was the rate-controlling step. [ABSTRACT FROM AUTHOR]

Critical assessment of plant polyphenols (ferulic acid, quercetin, caffeic acid, gallic acid, arbutin, proanthocyanide) that can be used for forming ordered mesoporous carbons (OMCs) via metal ion (Fe, Co, Ni, Zn, Zr, Mg, Ce, La) and bimetal ion (MgFe, CoNi) cross-linking chemistry is reported. In the methodology, coordination interactions between aromatic hydroxyl groups of polyphenol molecules and metal ion cross-linkers initiate OMC formation via ethanol evaporation induced self-assembly (EISA). Aromatic hydroxyl content, solubility in the evaporating solvent and low to moderate molecular mass are key factors in selecting plant polyphenols for OMC formation. The as-prepared metal-functionalized OMCs were applied to electrocatalytic reduction of nitrate to nitrogen (conversion 85.5%, nitrogen selectivity 99.8%), catalytic hydrogenation of furfural to tetrahydrofurfuryl alcohol (conversion 100%, tetrahydrofurfuryl alcohol selectivity 100%), and electrode materials for supercapacitors (specific capacitance, 222 F/g at 0.5 A/g). Using the proposed techniques, a wide range plant polyphenols can be used to form OMCs that are directly applicable to environmental applications after carbonization in a nitrogen atmosphere without further post-processing, doping or modification. [Display omitted] [ABSTRACT FROM AUTHOR]

In this work, a series of Ni/Organoclay catalysts with different Nickel loadings were prepared by the wet-impregnation method for the catalytic hydrogenation of levulinic acid (LA) to γ-valerolactone (GVL). Reaction parameters such as reaction temperature, pressure, solvent effect, and wt% of catalyst were optimized to get excellent conversion of levulinic acid selectively to γ-valerolactone. Ni/Organoclay with 30% Nickel loading exhibited 100% conversion of LA with 100% selectivity towards GVL at 140 °C and 3.0 MPa H 2 pressure using 1,4-dioxane as a solvent in 5 h. Different bulk and surface characterization techniques such as XRD, BET, FE-SEM, HR-TEM, XPS, XRF, NH 3 -TPD, and H 2 -Chemisorption were used to characterize the Ni/Organoclay catalyst. BET and NH 3 -TPD analysis showed that the pre-treatment of bentonite with surfactant (CTAB) improved the pore volume, surface area, and acidity of Organoclay which assisted in improving the conversion and selectivity of LA and GVL respectively. [Display omitted] • The calcination of catalyst in N 2 resulted in highly dispersed nickel particles. • Ni/Organoclay exhibits 100% LA conversion and 100% GVL selectivity. • 100% selectivity towards GVL was achieved in 1,4-dioxane. • Catalyst showed excellent hydrogenation activity even at 1.0 MPa H 2 pressure. [ABSTRACT FROM AUTHOR]

It is a green and environment-friendly strategy to use biomass to assist the synthesis of catalysts and use the prepared catalysts for biomass utilization. In this study, aluminum-rich silicon-phosphorus-aluminum nanosheet (Al-SPAN) was synthesized with biomass amino acids as additives for catalytic transfer hydrogenation of ethyl levulinate to γ-valerolactone. Compared with commercial Al 2 O 3 , Al-SPAN showed greatly improved catalytic performance for the reaction. The conversion of ethyl levulinate was increased by 47 % and the yield of γ-valerolactone was increased by 52 %. The effects of different alcohol on the reaction properties were investigated, with isopropanol used as a safe and efficient hydrogen source. The catalyst has good stability with little change in reaction performance after five cycles. [Display omitted] • Biomass amino acids were used to assist in the synthesis of catalysts. • The Al-rich nanosheets show good performance in the conversion of ethyl levulinate. • The aluminum site is efficient for catalytic transfer hydrogenation reaction. • Isopropanol could be used as a safe and efficient hydrogen source. [ABSTRACT FROM AUTHOR]

The stabilization and transport of the reactants, intermediates and products are significant to rational design of an industrial catalyst. In this work, we encapsulated the surface of Pd/g-C 3 N 4 catalyst with acrylic acid (AA) using a photo-induced grafting method to mimic the 3-dimensional nature of enzymes. A combined characterization and ab initio calculation revealed that AA ligands on the surface controlled the adsorption and diffusion behaviors of the reactants, rather than alter the electronic or geometric properties of Pd active centers. The optimized catalyst (Pd/CNA-4) significantly enhances isoprene partial hydrogenation activity without a decline in semi-hydrogenation selectivity. This approach can be further optimized by changing the types of the encapsulating ligands and can meet other specific catalytic reactions to regulate their conversion and selectivity and is therefore expected to extend to other areas of heterogeneous catalysis. In this work, we modified the support of Pd/g-C 3 N 4 with acrylic acid molecules and found that the optimized Pd/CNA-4 showed an improved isoprene semi-hydrogenation activity, reaching 8 times that of unmodified Pd/g-C 3 N 4 catalyst and 2.4 times that of commercial 5 wt% Pd/C catalyst, without obvious decline in partial hydrogenation selectivity or deactivation during 12-h test. Employing a combined characterization tool, this work revealed the mechanism of how the microenvironment confined by acrylic acid ligands influences the nature of the Pd active centers, as well as the adsorption and diffusion behaviors of the reactants. [Display omitted] [ABSTRACT FROM AUTHOR]

Hierarchical carbon superstructures that built from primary nanoscale objects and featured with a micro- or macroscopic architecture are highly desired, as credited by the synergistically integrated specialties. Here, we present a simple "microconfined-assembly-locking" approach to achieve pomegranate-like mesoporous carbon microspheres (PMCMs), in which the Pickering droplet-confined colloidal particle assembly and surfactant-directed interfacial locking are coupled. The formed PMCMs possess a unique micro-nano-hierarchical structure that consisting numerous mesoporous hollow carbon nanospheres within a permeable crust. Benefitting from this hierarchical arrangement, such a peculiar architecture not only preserves high surface area, large pore volume and good accessibility of the nano-building blocks, but also upgrades in mechanical strength and easy handling ability. In addition, this strategy allows the interior microstructures to be manipulated through combinatorial varying the assembled colloidal particles and interfacial chemical locking processes. Notably, the PMCMs show superior sorption capacity and cyclability for organics or oils from water in a fixed-bed system, which could also be applied to enhance the catalytic performance in hydrogenation of aromatic compounds after loading with Ru nanoparticles. This synthetic method provides a powerful bridge between nanoscale objects and microscale patterning, and paves a way to access other novel superstructures for expanding their potential applications. [Display omitted] [ABSTRACT FROM AUTHOR]

In this work, we prepared highly dispersed CeO 2 nanoparticle-modified Pd/Al 2 O 3 catalyst and applied it for the reversible hydrogenation and dehydrogenation of N-propylcarbazole. Compared with the commercially available 1 wt% Pd/Al 2 O 3 catalyst, the catalyst Pd/CeAl-20 exhibited better catalytic performance, realizing the full hydrogenation of N-propylcarbazole and the full dehydrogenation of perhydro-N-propylcarbazole within 180 min. Thus, it shows excellent commercial potential in large-scale applications. XRD and CO pulse chemisorption results indicated that CeO 2 improved the dispersion of Pd nanoparticles on the support surface. H 2 -TPR measurements indicated that CeO 2 weakened the strong interaction between the Pd particles and the support, inhibiting the formation of stable PdO. HRTEM images and XPS spectroscopic analysis show an apparent electronic transfer between Pd and CeO 2 at the Pd–CeO 2 interface. The formed Pd–O–Ce structure modulates the electronic state of the Pd particles, which contributes to the excellent catalytic performance of the Pd/CeAl-20 catalyst. This study reveals the crucial role of the combined promotion of the size of the active site and the chemical microenvironment for the reversible hydrogenation and dehydrogenation of N-heterocycles. [Display omitted] • A Ce-promoted highly active bifunctional Pd/Al 2 O 3 catalyst was introduced. • The catalyst was synthesized by co-precipitation method with supercritical drying. • Pd/CeAl-20 shows excellent activity for both hydrogenation and dehydrogenation. • The formed Pd–O–Ce structure modulates the electronic state of the Pd particles. • The Pd/CeAl-20 catalyst is very promising for application in LOHC technology. [ABSTRACT FROM AUTHOR]

Poly(acrylonitrile- co -butadiene) nanoparticles were synthesized by semibatch microemulsion polymerization. The microstructure of the polymers was characterized by 1H NMR and FT-IR. The particle size of the nitrile butadiene rubber (NBR) latex could be well controlled by reaction temperature, surfactant concentration, and feeding time of monomer. The minimum particle size of 34.2 nm could be achieved by using the surfactant/monomer mass fraction of 7.9 wt%. The latex can be directly catalyzed for hydrogenation using Wilkinson's catalyst (RhCl(PPh 3) 3) and second generation Grubbs catalyst (Grubbs II), respectively. The hydrogenated products (HNBR) with a degree of hydrogenation above 95 mol% were obtained. The fast rate of hydrogenation demonstrates the unique advantages of small particle size. [Display omitted] • NBR particles were synthesized by semibatch microemulsion polymerization. • The smallest particle size with 34 nm can be obtained. • Catalytic hydrogenation of diene-based polymers in aqueous solutions was realized. • Smaller NBR particles have faster mass transfer efficiency and hydrogenation rates. [ABSTRACT FROM AUTHOR]

Two pilot scale experiments investigating the one-step synthesis of methyl isobutyl ketone (MIBK) from acetone and hydrogen were conducted via catalytic distillation (CD) utilizing a Pd/Nb 2 O 5 /SiO 2 catalyst at a reaction temperature of 160 °C and system pressure of about 1.4 MPa. Moisture analysis of liquid samples extracted about the major axis of the CD column revealed that when the reactor was initially operated at 100% reflux as suggested in the patent of Lawson and Nkosi, water had accumulated in the top half of the reactor as evidenced by water concentrations of 9.4 and 21.0 wt% in the reactive and rectification sections respectively, resulting in the suppression of the DAA dehydration reaction and consequently a relatively low MIBK productivity. However, operation of the CD column at 83–97% reflux enabled the rapid in situ separation of water from the reactive section via the overhead distillate stream, which directly resulted in increases in the MIBK productivity and the hydrogen uptake efficiency by factors of about 20. This result demonstrates a unique advantage of CD technology, whereby a substantial kinetic enhancement may be realized from the selective in situ separation of a kinetically relevant inhibiting substrate from the reactant mixture. MIBK in excess of 50 wt% was observed in the reboiler product during this mode of operation, which is significant since state of the art processes for MIBK production typically yield less than 30 wt% MIBK in the reactor effluent. The reboiler product was found to be essentially moisture free, which is also significant since MIBK and water are known to produce azeotropic mixtures resulting in difficult and costly downstream separations. An experiment was conducted to study the effects of the hydrogen and reflux flow rates on the MIBK yield. The CD process for MIBK synthesis was found to be controlled by the rate of external mass transfer of hydrogen. The results indicate that the catalyst wetting efficiency affects the catalytic hydrogenation as evidenced by an increase in mesityl oxide conversion with decreasing reflux flow rate. This suggests the catalyst wetting efficiency is an important design criterion for this process. CD reactor bottoms product composition as a function of time-on-stream (TOS). Conclusion Operating the CD reactor under conditions of total reflux as described in the patents of Lawson and Nkosi resulted in the suppression of the DAA dehydration reaction due to the accumulation of water in the reactive section. Changing the mode of operation after condition #1 to include an overhead distillate stream, resulted in the rapid removal of water from the reaction section and the enhancement of both the catalyst activity and the hydrogen uptake efficiency by a factor of 20, enabling a moisture free MIBK product in excess of 50 wt%, which is an advancement in the state of the art. [Display omitted] • Catalyst activity was enhanced by a factor of 20 via the in situ removal of a kinetically relevant inhibiting substrate. • Catalyst wetting efficiency is a key reactor design consideration. • Mesityl oxide and MIBK syntheses are governed by competing transport processes. [ABSTRACT FROM AUTHOR]

Concave nanomaterials possess superior properties, but their synthesis usually requires complicated steps, specific conditions and additional reagents (surfactants, capping agents, seeds, etc.). Herein, the well-defined Au@Pd concave nanocubes (CNCs) is facile one-step fabricated in a deep eutectic solvent (DES, named reline) composed of choline chloride (ChCl) and urea. It is found that the reline is crucial to the formation of Au@Pd CNCs. Owing to the concave core-shell structures, and electronic effects between Au core and Pd shell, Au@Pd CNCs exhibited excellent catalytic performance, and recovery convenience in the selective hydrogenation of 4-nitrostyrene. Specifically, under normal temperature and pressure conditions (25°C, 0.1 MPa), 4-nitrostyrene can be completely hydrogenated to 4-nitroethylbenzene within 7.0 min. After five cycles, Au@Pd CNCs still maintain the highly catalytic activity and 100 % selectivity toward 4-nitroethylbenzene. It is expected that well-constructed Au@Pd CNCs also display advanced potentials in other applications. • The facile and eco-friendly one-step method for the synthesis of bimetallic Au@Pd core-shell concave nanocubes. • Without uses of any surfactants, templating agents, capping agents and seeds. • 100 % conversion is achieved at 25°C within 7.0 min under atmospheric pressure. • Catalytic hydrogenation selectivity to 4-nitroethylbenzene is as high as 100 %. [ABSTRACT FROM AUTHOR]

Developing cost-effective and highly active catalysts for the selective hydrogenation of furfural to target products is significant yet remains a substantial conundrum in the chemical industry. Herein, we present a phytic acid-assisting pyrolysis strategy to phase-controlled synthesis of a series of nickel phosphides catalysts (Ni 3 P/mSiO 2 , Ni 12 P 5 /mSiO 2 and Ni 2 P/mSiO 2), which exhibited phase-dependent catalytic performance in furfural hydrogenation. Ni 12 P 5 /mSiO 2 achieved the highest yield (97.3 %) of cyclopentanone under 1 MPa H 2 at 150 °C, and Ni 3 P/mSiO 2 could further hydrogenate cyclopentanone to a 60.8 % yield of cyclopentanol when the H 2 pressure increased to 2 MPa. Meanwhile, Ni 2 P/mSiO 2 demonstrated temperature-controlled selectivity for switching between furfuryl alcohol and cyclopentanone. Detailed characterizations and density functional theory calculations elucidated that the differences in catalytic performance were primarily attributed to the hydrogenation ability and acidity of catalysts as well as furfural adsorption configuration, which were determined by the tunable crystal phases of nickel phosphides. This work paves the promising avenue for the rational design of metal phosphide catalysts and harnessing their considerable potential for biomass conversion. [Display omitted] • Phytic acid-assisting pyrolysis strategy was proposed for phase-controlled synthesize nickel phosphide catalysts. • Nickel phosphide catalysts show interesting phase-dependent catalytic performance for hydrogenation of furfural. • Phase-tuning induced increase of available catalytic active sites and optimization of surface electronic structures. • DFT calculations reveal the promotional effect of tilted adsorption configuration for hydrogenation rearrangement. [ABSTRACT FROM AUTHOR]

The catalytic hydrogenation of CO 2 to high-carbon linear α-olefins (LAOs; C ≥ 4) has gained considerable attention. In this study, FeMnK catalysts were synthesised using an organic combustion method. The introduction of Mn promoted the dispersion of Fe species and enhanced the formation of the iron oxides, whereas the introduction of K promoter led to the formation of iron carbides and improved the carbon chain-growth capability of catalysts. The mechanistic studies revealed that the addition of Mn and K regulated the matching of reverse water gas shift and subsequent Fischer–Tropsch synthesis reactions by enhancing the formation and further conversion of CO intermediate. The selectivity and productivity of LAOs were 45.7 % and 0.236 g∙g cat −1∙h−1, respectively, under the reaction condition of 320 °C, 2 MPa and 20000 mL∙g cat −1∙h−1. Furthermore, FeMn0.1K0.1 exhibited excellent stability for up to 160-h on stream, demonstrating promising industrial application prospects for CO 2 conversion into value-added fuels and chemicals. [Display omitted] • Fe catalysts decorated with Mn and K for CO 2 hydrogenation to linear α-olefins. • Mn promotes the dispersion of Fe species and enhances the formation of FeO y phases. • K promotes the formation of Fe 5 C 2 and improves the carbon chain-growth capability. • Mn and K promoters regulate the matching of RWGS and subsequent FTS reactions. • The as-prepared FeMn0.1K0.1 exhibits the best performance with excellent stability. [ABSTRACT FROM AUTHOR]