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Using acetate as the precursor, different proportions of Cu/Zn catalysts were prepared by hydrothermal method, and the performance of CO2 hydrogenation to methanol was evaluated without H2 pretreatment. The effects of different Cu/Zn ratios on the crystalline phase structure, surface properties and valence state of the catalyst were investigated by XRD, TG-DSC, H2-TPR, CO2 temperature-programmed desorption and XPS, and its active sites were studied. The results show that the activity of the Cu/Zn catalyst prepared with acetate as the precursor is evaluated without pretreatment, and the H2 in the reaction gas (H2 : CO2 =3 : 1) will reduce the Cu2+ of the Cu/Zn catalyst to Cu° to form a new Cu0-ZnO interface, which makes the Cu/Zn45 achieve a spatiotemporal yield of 7.97 mmol/(g· h) at 3 MPa and 240 °C. [ABSTRACT FROM AUTHOR]

Significant interest has emerged for the application of Pd-In2O3 catalysts as high-performance catalysts for CO2 hydrogenation to CH3OH. However, precise active site control in these catalysts and understanding their reaction mechanisms remain major challenges. In this investigation, a series of Pd-InOx catalysts were synthesized, revealing three distinct types of active sites: In-O, Pd-O(H)-In, and Pd2In3. Lower Pd loadings exhibited Pd-O(H)-In sites, while higher loadings resulted in Pd2In3 intermetallic compounds. These variations impacted catalytic performance, with Pd-O(H)-In catalysts showing heightened activity at lower temperatures due to the enhanced CO2 adsorption and H2 activation, and Pd2In3 catalysts performing better at elevated temperatures due to the further enhanced H2 activation. In situ DRIFTS studies revealed an alteration in key intermediates from *HCOO over In-O bonds to *COOH over Pd-O(H)-In and Pd2In3 sites, leading to a shift in the main reaction pathway transition and product distribution. Our findings underscore the importance of active site engineering for optimizing catalytic performance and offer valuable insights for the rational design of efficient CO2 conversion catalysts.

Cu/ZnO/C–P were prepared via the deposition-precipitation for CO 2 hydrogenation to methanol. At 280 °C, Cu/ZnO/C–P reached the maximum methanol space-time yield (STY) of 0.66 g CH3OH ·g cat −1·h−1, significantly higher than Cu/ZnO (0.48 g CH3OH ·g cat −1·h−1). The addition of C–P escalated the reduction of Cu2+ and made Cu/ZnO interface much tighter. Phosphorus-doped Carbon (C–P) was not only favorable for the formation of Cu/ZnO contact interfaces and boosted Cu0 amount at the Cu/ZnO interfaces, but also further strengthened the interaction between Cu0 and ZnO. Cu0/ZnO interfaces also improved the adsorption and activation of CO 2 and H 2 , eventually advanced methanol formation. The variation trend between methanol STY and Cu0 species content at the Cu/ZnO interface was in good agreement with each other. Cu0 species strongly interacted with ZnO at the Cu/ZnO contact interfaces may be indispensable for methanol generation on Cu/ZnO/C–P. The Cu0/ZnO interface serves as the active center to efficiently escalate CO 2 hydrogenation to methanol. [Display omitted] • Phosphorus-doped carbon materials were synthesized using a simple hydrothermal method. • C–P promoted the generation of Cu/ZnO interfaces and enhanced the interaction between Cu0 and ZnO. • Cu0/ZnO interfaces were the active sites of Cu/ZnO/C–P for CO 2 hydrogenation to methanol. • Cu/ZnO modified by appropriate amount of C–P promoted the methanol formation. [ABSTRACT FROM AUTHOR]

Gallium oxide‐based catalysts are promising candidates for CO2 hydrogenation to methanol, whilst mechanistic understanding of the catalytic systems is not yet fully understood. Here, transient in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) studies of CO2 hydrogenation over the unsupported CuGa and CuGaN (with N doping) catalysts were conducted. The findings show that N doping could possibly promote the formation of surface Cu+ sites on the interface between Cu and Ga2O3, and hence increasing the selectivity to methanol. However, N doping prohibited the reduction of Ga2O3 to oxygen‐deficient Ga2O3‐x, which is unfavorable for CO2 conversion. Additionally, during DRIFTS the steady‐state isotope transient kinetic analysis (SSITKA) was performed (under H2/D2 isotopic switching conditions). The SSITKA results confirm that the Cu+‐bound formates were likely the key intermediates for methanol synthesis over the catalyst, and the N doping could also weak the interaction between CO* species and the catalyst surface, and thus facilitating the selectivity towards methanol rather than CO. Findings of the work show that the partial nitridation of the metal oxides could be the strategy to promote methanol synthesis selectivity. [ABSTRACT FROM AUTHOR]

This article explores the influence of the Mg/Al molar ratio on the performance of CuMgAl-x catalysts for CO2 hydrogenation to methanol. The study found that developing catalysts with highly dispersed Cu nanoparticles and efficient active interfaces is crucial for promoting CO2 hydrogenation to methanol. The results showed that the CuMgAl-3 catalyst exhibited the smallest Cu particle size and good dispersion, leading to the highest CO2 conversion and methanol selectivity. The study suggests that the Mg/Al molar ratio and Cu dispersion play important roles in the catalytic activity of CuMgAl-x catalysts. [Extracted from the article]

In 2 O 3 has been found a promising application in CO 2 hydrogenation to methanol, which is beneficial to the utilization of CO 2. The oxygen vacancy (O v) site is identified as the catalytic active center of this reaction. However, there remains a great challenge to understand the relations between the state of oxygen species in In 2 O 3 and the catalytic performance for CO 2 hydrogenation to methanol. In the present work, we compare the properties of multiple In 2 O 3 and Ir-promoted In 2 O 3 (Ir-In 2 O 3) catalysts with different Ir loadings and after being pretreated under different reduction temperatures. The CO 2 conversion rate of Ir-In 2 O 3 is more promoted than that of pure In 2 O 3. With only a small amount of Ir loading, the highly dispersed Ir species on In 2 O 3 increase the concentration of O v sites and enhance the activity. By finely tuning the catalyst structure, Ir-In 2 O 3 with an Ir loading of 0.16 wt.% and pre-reduction treatment under 300°C exhibits the highest methanol yield of 146 mg CH3OH /(g cat ·hr). Characterizations of Raman, electron paramagnetic resonance, X-ray photoelectron spectroscopy, CO 2 -temperature programmed desorption and CO 2 -pulse adsorption for the catalysts confirm that more O v sites can be generated under higher reduction temperature, which will induce a facile CO 2 adsorption and desorption cycle. Higher performance for methanol production requires an adequate dynamic balance among the surface oxygen atoms and vacancies, which guides us to find more suitable conditions for catalyst pretreatment and reaction. [ABSTRACT FROM AUTHOR]

The potential of metal oxide supported Au catalysts for the formation of methanol from CO2 and H2 under conditions favorable for decentralized and local conversion, which could be concepts for chemical energy storage, was investigated. Significant differences in the catalytic activity and selectivity of Au/Al2 O3 , Au/TiO2 , AuZnO, and Au/ZrO2 catalysts for methanol formation under moderate reaction conditions at a pressure of 5 bar and temperatures between 220 and 240 °C demonstrate pronounced support effects. A high selectivity (>50 %) for methanol formation was obtained only for Au/ZnO. Furthermore, measurements on Au/ZnO samples with different Au particle sizes reveal distinct Au particle size effects: although the activity increases strongly with the decreasing particle size, the selectivity decreases. The consequences of these findings for the reaction mechanism and for the potential of Au/ZnO catalysts for chemical energy storage and a "green" methanol technology are discussed., (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

The urgent need to address global carbon emissions and promote sustainable energy solutions has led to a growing interest in carbon dioxide (CO 2 ) conversion technologies. Among these, the transformation of CO 2 into methanol (MeOH) has gained prominence as an effective mitigation strategy. This review paper provides a comprehensive exploration of recent advances and applications in the direct utilization of CO 2 for the synthesis of MeOH, encompassing various aspects from catalysts to market analysis, environmental impact, and future prospects. We begin by introducing the current state of CO 2 mitigation strategies, highlighting the significance of carbon recycling through MeOH production. The paper delves into the chemistry and technology behind the conversion of CO 2 into MeOH, encompassing key themes such as feedstock selection, material and energy supply, and the various conversion processes, including chemical, electrochemical, photochemical, and photoelectrochemical pathways. An in-depth analysis of heterogeneous and homogeneous catalysts for MeOH synthesis is provided, shedding light on the advantages and drawbacks of each. Furthermore, we explore diverse routes for CO 2 hydrogenation into MeOH, emphasizing the technological advances and production processes associated with this sustainable transformation. As MeOH holds a pivotal role in a wide range of chemical applications and emerges as a promising transportation fuel, the paper explores its various chemical uses, transportation, storage, and distribution, as well as the evolving MeOH market. The environmental and energy implications of CO 2 conversion to MeOH are discussed, including a thermodynamic analysis of the process and cost and energy evaluations for large-scale catalytic hydrogenation., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

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]

Carbon coated In 2 O 3 hollow tube catalysts embedded with ultra-low content ZnO quantum dots (QDs) were synthesized for CO 2 hydrogenation to methanol. [Display omitted] • Carbon coated In 2 O 3 hollow tubes embedded with ultra-low content ZnO QDs were obtained. • The QD heterojunction boosted the CO 2 adsorption and accelerated the electron transfer from In3+ to Zn2+. • The carbon acted as a medium for hydrogen spillover and promoted the electron transfer. • ZnO QDs facilitated the H 2 dissociation and activation. • The highest methanol STY could reach 0.98 g MeOH h−1 g cat −1 on ZnO-In 2 O 3 -II at 350 °C and 3 MPa. CO 2 hydrogenation coupled with renewable energy to produce methanol is of great interest. Carbon coated In 2 O 3 hollow tube catalysts embedded with ultra-low content ZnO quantum dots (QDs) were synthesized for CO 2 hydrogenation to methanol. ZnO-In 2 O 3 -II catalyst had the highest CO 2 and H 2 adsorption capacity, which demonstrated the highest methanol formation rate. When CO 2 conversion was 8.9%, methanol selectivity still exceeded 86% at 3.0 MPa and 320 °C, and STY of methanol reached 0.98 g MeOH h−1g cat −1 at 350 °C. The ZnO/In 2 O 3 QDs heterojunctions were formed at the interface between ZnO and In 2 O 3 (2 2 2). The ZnO/In 2 O 3 heterojunctions, as a key structure to promote the CO 2 hydrogenation to methanol, not only enhanced the interaction between ZnO and In 2 O 3 as well as CO 2 adsorption capacity, but also accelerated the electron transfer from In3+ to Zn2+. ZnO QDs boosted the dissociation and activation of H 2. The carbon layer coated on In 2 O 3 surface played a role of hydrogen spillover medium, and the dissociated H atoms were transferred to the CO 2 adsorption sites on the In 2 O 3 surface through the carbon layer, promoting the reaction of H atoms with CO 2 more effectively. In addition, the conductivity of carbon enhanced the electron transfer from In3+ to Zn2+. The combination of the ZnO/In 2 O 3 QDs heterojunctions and carbon layer greatly improved the methanol generation activity. [ABSTRACT FROM AUTHOR]

[Display omitted] • The CO 2 hydrogenation to methanol process has been studied on In 4 O 6 /ZrO 2 (1 1 1) surfaces by using periodic density functional theory calculations. • Various active sites have been explored, revealing that the D 1 surface featuring Ov 1 defects within the In 4 O 6 cluster is thermodynamically favorable, thereby facilitating the activation and hydrogenation of CO 2. • The presence of Ov 4 defects at the interface of the D 4 surface, along with the adsorption of CO 2 at the interfacial site, results in a thermodynamically more favorable hydrogenation process to produce HCOO*. Methanol synthesis from CO 2 hydrogenation on the defective In 4 O 6 /ZrO 2 (1 1 1) surface with surface oxygen vacancies has been investigated by using periodic density functional theory calculations. The calculated oxygen vacancy formation energies indicate that the D1 surface with O v1 defective sites on the surface of the In 4 O 6 clusters is thermodynamically the most favorable for the adsorbed CO 2 to generate methanol along the HCOO pathway. In contrast, the D4 surface with O v4 defect sites at the interface is the most unstable, reacting along the RWGS path on clusters near the O v4 defects, and hydrogenating along the HCOO path at the interfacial position to generate methanol. The differential charge density curves further reveal the close relationship between the electronic structure of the metal oxide interface and the CO 2 hydrogenation mechanism to methanol. [ABSTRACT FROM AUTHOR]

Ternary Pd‐In2O3/ZrO2 catalysts exhibit technological potential for CO2‐based methanol synthesis, but developing scalable systems and comprehending complex dynamic behaviors of the active phase, promoter, and carrier are key for achieving high productivity. Here, we show that the structure of Pd‐In2O3/ZrO2 systems prepared by wet impregnation evolves under CO2 hydrogenation conditions into a selective and stable architecture, independent of the order of addition of Pd and In phases on the zirconia carrier. Detailed operando characterization and simulations reveal a rapid restructuring driven by the metal‐metal oxide interaction energetics. The proximity of InPdx alloy particles decorated by InOx layers in the resulting architecture prevents performance losses associated with Pd sintering. The findings highlight the crucial role of reaction‐induced restructuring in complex CO2 hydrogenation catalysts and offer insights into the optimal integration of acid‐base and redox functions for practical implementation. [ABSTRACT FROM AUTHOR]

[Display omitted] • CuCeO x /TiO 2 and CuCeO x /SiO 2 (6% wt. Cu) with different amounts of CeO 2 were prepared. • CeO 2 strongly promotes methanol synthesis, in contrast to recently published results. • Both families of catalysts exhibit the same CH 3 OH kinetics but different selectivity. • The structural impact of TiO 2 was related to the inhibition of the r-WGSR. • Operando- DRIFTS show that HCOO– at the Cu-Ce interface are likely reaction intermediates. Ce promotion increases the rate of methanol formation by two orders of magnitude compared to Cu/TiO 2 and Cu/SiO 2 catalysts. The promotion proceeds via the generation of a new active site in which Ce3+ intervenes at the interface with Cu, without significant influence of the support identity. For higher promoter concentrations (Ce/(Cu + Ce) greater than 0.3), additional active sites are not further generated due to the saturation of the space around copper clusters. TiO 2 -supported samples presented higher methanol selectivity (ca. 80% at 220 °C and 8 bar) compared to the ones supported on SiO 2 (ca. 20%), due to an inhibition of the r-WGSR related to the strong metal support interaction between Cu and TiO 2 , which blocks surface sites responsible for CO production. Operando – DRIFTS further verified that the mechanism for methanol formation is the same between both families of catalysts and that it likely proceeds via the generation of formates at the Cu – Ce interface. [ABSTRACT FROM AUTHOR]

CO2 hydrogenation to methanol has emerged as a promising strategy for achieving carbon neutrality and mitigating global warming, in which the supported Pd/In2O3 catalysts are attracting great attention due to their high selectivity. Nonetheless, conventional impregnation methods induce strong metal‐support interaction (SMSI) between Pd and In2O3, which leads to the excessive reduction of In2O3 and the formation of undesirable PdIn alloy in hydrogen‐rich atmospheres. Herein, we innovatively synthesized Pd/In2O3 nanocatalysts by the electrostatic self‐assembly process between surface‐modified composite precursors with opposite charges. And the organic ligands concurrently serve as Pd nanoparticle protective agents. The resultant Pd/In2O3 nanocatalyst demonstrates the homogeneous distribution of Pd nanoparticles with controllable sizes on In2O3 supports and the limited formation of PdIn alloy. As a result, it exhibits superior selectivity and stability compared to the counterparts synthesized by the conventional impregnation procedure. Typically, it attains a maximum methanol space‐time yield of 0.54 gMeOH h−1gcat−1 (300 °C, 3.5 MPa, 21,000 mL gcat−1 h−1). Notably, the correlation characterization results reveal the significant effect of small‐size, highly dispersed Pd nanoparticles in mitigating MSI. These results provide an alternative strategy for synthesizing highly efficient Pd/In2O3 catalysts and offer a new insight into the strong metal‐support interaction. [ABSTRACT FROM AUTHOR]

In this work, sequential incipient wetness impregnation method was used to synthesize Cu/Al 2 O 3 , Cu/Na 2 O/Al 2 O 3 and Cu/CaO/Al 2 O 3 catalysts in different compositions for CO 2 conversion to value-added products. Synthesized catalysts were characterized using various analytical techniques and their performances for CO 2 catalytic conversion were tested in a high-pressure packed bed reactor under reaction conditions of P = 60 bars, T = 300 °C, and H 2 /CO 2 = 3. The obtained results revealed that the type of adsorbent had a significant impact on CO 2 conversion, with CaO-containing catalyst being more efficient for methanol selectivity. Increased Cu content from 10 wt% to 30 wt% with fixed CaO content of 10 wt% resulted in a small increase in CO 2 conversion where the highest CO 2 conversion of 16.44% and the highest methanol selectivity (17.75%) were obtained for catalyst containing 20 wt% of copper. The best performing catalyst was further promoted using 0.5 wt% Rh promoter which improved both methanol selectivity and space time yield to 23.2% and 0.08 g MeOH g cat −1h−1, respectively. The comparative high performance of the Rh-promoted catalyst was attributed to smaller metal oxide particle size with uniform dispersion, presence of effective hydrogen spill over, moderate basic sites, surface defects and presence of induced copper species. • Development of Cu/Na 2 O/Al 2 O 3 and Cu/CaO/Al 2 O 3 Catalysts via sequential wetness impregnation method. • Characterization of catalysts by various surface and bulk sensitive analytical tools such as XRD, HRTEM, XPS, H 2 -TPR, H 2 -TPD, and CO 2 -TPD. • The performance of the Synthesized catalysts for CO 2 hydrogenation to methanol at 300 ℃. • Calcium oxide-based catalyst exhibited the highest overall catalytic performance. [ABSTRACT FROM AUTHOR]

Hydrogenation of CO2 to form methanol utilizing green hydrogen is a promising route to realizing carbon neutrality. However, the development of catalyst with high activity and selectivity to methanol from the CO2 hydrogenation is still a challenge due to the chemical inertness of CO2 and its characteristics of multi-path conversion. Herein, a series of highly active carbon-confining molybdenum sulfide (MoS2@C) catalysts were prepared by the in-situ pyrolysis method. In comparison with the bulk MoS2 and MoS2/C, the stronger interaction between MoS2 and the carbon layer was clearly generated. Under the optimized reaction conditions, MoS2@C showed better catalytic performance and long-term stability. The MoS2@C catalyst could sustain around 32.4% conversion of CO2 with 94.8% selectivity of MeOH for at least 150 h.

Development of novel catalyst for CO2 conversion to methanol is still a challenge. A series of Cu/CeO2 catalyst were prepared by changing the synthesis procedure. The Cu/CeO2 catalyst were prepared by co‐precipitation, surfactant‐assisted co‐precipitation, and sol‐gel methods for CO2 hydrogenation to methanol are documented. The performance of these catalysts was evaluated to elucidate the role of catalytic properties. The Cu/CeO2 catalyst synthesized by the sol‐gel (Cu/CeO2−SG) method exhibited superior strong basic site density, Cu dispersion, and oxygen vacancy defects than co‐precipitation method. A correlation between strong basic site density, oxygen vacancies, and methanol space time yield was established. Moreover, the promotional role of Cu−Ce interfacial sites on the reduced Cu4t/CeO2(111) cluster in CO2 adsorption and activation has been reported by the DFT calculation. These experimental and theoretical results provide insights into Cu‐CeO2 interaction and role of metal‐support interactions in the CO2 hydrogenation reaction. [ABSTRACT FROM AUTHOR]

[Display omitted] • Electron-rich interface was created by introduction of TiO 2 into Al 2 O 3 support. • Adsorption and activation of CO 2 and carbonyl species are enhanced. • The reaction rate controlling step for RWGS pathway changed. • RWGS pathway becomes the dominant pathway. • Cu 13 /Ga-AT is a promising catalyst for CO 2 directional hydrogenation to methanol. Density functional theory investigations on CO 2 hydrogenation to methanol mechanisms over Cu 13 cluster loaded catalyst were performed. The results indicate that introducing TiO 2 into Al 2 O 3 promoted the residual electrons from Al 2 O 3 surface directionally transmitted to the interface formed by the loaded Cu 13 cluster and the support surface, thus created the electron-rich active interface. Incorporating single atom Ga promoter further gathered the residual electrons and stabilized the loaded Cu 13 clusters. The electron-rich property of the active interface promoted the chemical adsorption and activation of both CO 2 and the generated carbonyl species. Further favors the hydrogenating of carbonyl intermediates to methanol and effectively enhances the methanol selectivity. Moreover, CO 2 priors to hydrogenated to methanol via reverse water gas shift pathway over Cu 13 /Ga-AT computational model with changed reaction rate controlling step with reduced activation energy. This work offers a simple approach for efficient copper-based methanol synthesis catalysts through control of interface electron structure. [ABSTRACT FROM AUTHOR]

• A theoretical study of the structure, electronic, and reaction mechanism of CO 2 to methanol on In 3 Ru(212) surfaces with different surface In/Ru ratio. • In 3 Ru could achieve high methanol selectivity by adding a H 2 O into each elementary step because it benefits the O H formation process. Designing high-performance catalyst is vital in the field of CO 2 methanolization. In this study, two In 3 Ru surfaces (In 3 Ru_i and In 3 Ru_r) were employed as computational models and the density functional theory was applied to study the influence of surface In/Ru ratio on their surface morphologies, reaction mechanisms and catalysis performance for methanol synthesis. Surface characterization reveals that In 3 Ru_i is higher in surface In/Ru ratio than In 3 Ru_r, and such difference facilitates CO 2 adsorption on In 3 Ru_r. Being different in surface In/Ru ratio, two surfaces exhibit distinct variations in the reaction mechanism of methanol formation. For In 3 Ru_i, the "Formate" pathway dominates the first CO 2 activation step which leads to methanol production. On the other hand, In 3 Ru_r prefers the "reverse water-gas shift" pathway (RWGS) in the initial step of CO 2 activation, but this mechanism is unable to generate CH 3 OH due to the kinetic limitation of CO* hydrogenation. Based on the microkinetic modeling, In 3 Ru_i is superior in both CO 2 production rate and CH 3 OH selectivity than the other one, suggesting higher surface In/Ru ratio benefits methanol formation, which complies well with the experiment. Overall, our study offers a new perspective with respect to how surface morphology of the bimetallic catalyst influences the reaction mechanisms of CO 2 hydrogenation. [Display omitted] [ABSTRACT FROM AUTHOR]

A series of Cu@ZrO 2 -U framework catalysts derived from Cu@UiO-67 precursors with adjustable copper loadings were constructed by the deposition-precipitation method, and the catalytic activities of methanol synthesis via CO 2 hydrogenation were investigated. The optimized 20-Cu@ZrO 2 -U catalyst showed the best catalytic activity. At 3 MPa and 260 °C, the space-time yield of CH 3 OH (STY CH3OH) reached 2.28 mmol CH3OH /(g cat ·h), which was 3.5 times higher than that of 20-Cu/ZrO 2. The catalyst of 20-Cu@ZrO 2 -U also showed good stability during the 100-h time on stream test. The catalysts were further characterized by XRD, N 2 sorption, TEM, XPS, H 2 -TPR, CO 2 /H 2 -TPD and in situ DRIFTS. The characterization results showed that the stable ZrO 2 framework derived from UiO-67 is propitious to the confine of copper nanoparticles and formation of Cu+-ZrO 2 interfacial sites, which should be responsible for the excellent performance of methanol synthesis. Moreover, in situ DRIFTS was used to probe that the methanol synthesis via CO 2 hydrogenation over 20-Cu@ZrO 2 -U follows a HCOO∗-intermediated reaction pathway. [Display omitted] • A novel Cu@ZrO 2 -U framework catalyst was constructed by Cu@UiO-67 precursor strategy. • The optimized catalyst of 20-Cu@ZrO 2 -U was shown to form rich Cu+-ZrO 2 interfaces. • The methanol yield of 20-Cu@ZrO 2 -U was 3.5 times higher than 20-Cu/ZrO 2 catalyst. • The methanol productivity depends on the ratio of Cu+/Cu0 regulated by Cu+-ZrO 2 interface. • The methanol synthesis mechanism of Cu@ZrO 2 -U follows a HCOO∗-intermediate pathway. [ABSTRACT FROM AUTHOR]

CO 2 hydrogenation to methanol process could effectively eliminate CO 2 emissions and convert CO 2 into different chemicals with H 2 produced via green energy. However, the catalysts for the CO 2 hydrogenation process suffer from lower CO 2 conversion, methanol selectivity, and deactivation. In this study, Cu/CeZrO x solid solution catalyst is prepared (Cu/CeZrO x -M) via a new microimpinging stream reactor coupled with ultrasound. Due to its better micromixing efficiency, the Cu/CeZrO x -M catalyst has smaller particle size and larger BET surface area than that prepared via the conventional batch method (Cu/CeZrO x -B). The Cu/CeZrO x -M catalyst exhibits a higher methanol STY of 222.4 g MeOH /kg cat /h with CO 2 conversion of 4.67% and methanol selectivity of 55.6% at 240 °C, and possesses better stability. Combined with the characterizations of structural and electronic state, catalytic higher performance is attributed to the synergistic effect between the oxygen vacancies and higher ratio of Cu+. In-situ DRIFTS reveals that the Cu/CeZrO x -M catalyst follows the formate-intermediated pathway, effectively transferring the formate intermediate into methanol. Furthermore, the microimpinging stream reactor could achieve the precursor solution transmission rate with 10 mL/s. This work provides a novel method for the high-performance catalyst preparation and its mechanism study gives a deep insight into high-performance catalysts development via the bottom-up study. [ABSTRACT FROM AUTHOR]

[Display omitted] • Mononuclear Ren+ species are introduced into In 2 O 3 for highly efficient methanol synthesis from CO 2 hydrogenation. • Mononuclear Re sites on In 2 O 3 promote heterolytic H 2 dissociation. • In 2 O 3 supported mononuclear Re decreases the energy barrier of rate-determining step in formate pathway compared with In 2 O 3 catalyst. Catalytic hydrogenation of CO 2 to methanol utilizing H 2 derived from renewable energy represents one of the most prospective strategies for the sustainable recycle of carbon. Accordingly, the design and preparation of high-performance catalysts for methanol production has received broad attention. Herein, In 2 O 3 supported mononuclear Re is reported to be an efficient catalyst for methanol production which exhibits methanol selectivity of up to 80% at CO 2 conversion of 11.5%, providing a methanol STY of 758 mg·h−1·g cat −1 under 5 MPa and 300 °C, more than twice as that for pristine In 2 O 3 (376 mg·h−1·g cat −1). The apparent reaction orders of CO 2 and H 2 were determined to be around 0 and 0.6 respectively, suggesting the activation of H 2 is more crucial compared with CO 2. In-depth characterizations reveal that the remarkably improved performance originates from the mononuclear Ren+ sites strongly interacting with In 2 O 3 , which significantly enhance the ability of H 2 dissociation. Combined experimental and theoretical studies proved the feasibility of formate pathway over In 2 O 3 supported mononuclear Re catalyst. The results of DFT calculations suggest that mononuclear Re site on In 2 O 3 (1 1 1) model plays a vital role on heterolytic H 2 dissociation and intermediates transformation, boosting the formation of HCOO* and lowering the energy barriers of rate-determining step for methanol formation. [ABSTRACT FROM AUTHOR]

A series of Cu−Mn−(La)−Zr catalysts with molecular ratios of 6 : 3 : (0.35) : 1 was synthesized by sol‐gel (CMLZ−S), co‐precipitation (CML−CP, CMLZ−CP) and hydrothermal (CMLZ−H) methods, respectively. The effects of the Mn and La on the activity of catalysts were investigated. It was found that the addition of La promoted the formation of the medium basic sites. Mn acted as an electronic promotor that transfer electrons through redox reactions, causing other metals to exhibit different valence states, thus promoting the adsorption and activation of H2 and CO2. At a certain temperature, methanol selectivity decreased in the order of CMLZ−H>CMLZ−S>CMLZ−CP>CMZ−CP. The selectivity of methanol is correlated with the distribution of basic sites. For the CMLZ−H catalyst, the highest percentage of moderate basic sites facilitated the activation of CO2, resulting in the highest selectivity of methanol. The CO2 conversion was correlated with the Cu specific surface area. [ABSTRACT FROM AUTHOR]

• The highest methanol STY (9.4 mmol/g cat /h) is obtained (X CO2 = 6.9 %, S MeOH = 93.3 %) on the optimized Pd/25 % α-MoC 1−x /C-N catalyst. • In situ DRIFTS experiments confirm the combined RWGS + CO-hydro and format mechanism in methanol synthesis. It is a potentially desirable process of utilizing CO 2 as a feedstock to make valuable chemicals such as methanol. Results from the current study demonstrate Pd modified α-MoC 1−x is a high active and selective catalyst for CO 2 hydrogenation to methanol. α-MoC 1−x is active for both methanol synthesis and RWGS reaction. The addition of 0.1 wt% Pd to α-MoC 1−x decreases the CO 2 hydrogenation reaction activation energy and increases the CH 3 OH selectivity due to the H 2 spillover effect of Pd. RWGS + CO-hydro pathway as a non-competitive parallel pathway to the dominant formate pathway is verified on Pd/α-MoC 1−x /C-N, which increases threefold methanol STY compared with α-MoC 1−x /C-N catalyst. This work supplies a feasible strategy for creating a dual active site to enhance the efficiency of methanol synthesis. [ABSTRACT FROM AUTHOR]

The development of effective catalysts for the hydrogenation of CO 2 to methanol is a crucial step in enhancing the efficiency of the green synthesis of chemicals and fuels. Herein, we investigated the use of transition metal carbides in CO 2 hydrogenation at low temperatures (160–200 °C). Mo 2 C-based catalysts synthesized in a vertical fixed-bed reactor exhibited 3–4 times higher activity than the catalyst synthesized in a horizontal reactor from open bulk in a boat vessel. This difference in activity is likely due to the lower surface area of the catalyst obtained by the latter method, as well as the non-uniform and incomplete formation of the Mo 2 C phase. The study also demonstrates that unpromoted Mo 2 C produced more methane and higher alkanes, indicating the potential of Mo 2 C in the CO 2 hydrogenation to hydrocarbons. Additionally, Cu/Mo 2 C was 3.75 times more active than unpromoted Mo 2 C at 160 °C, with higher selectivity towards methanol. CH 3 OH was the predominant product over Cu/Mo 2 C in the temperature range of 160–200 °C. The experiments aimed to elucidate the reaction mechanism over Cu/Mo 2 C catalyst in CO 2 hydrogenation to identify primary and secondary products. [Display omitted] • Synthesis parameters leading to complete carburization of TMCs were established. • Primary and secondary products in CO 2 hydrogenation over Cu/Mo 2 C were determined. • Mo 2 C-based catalysts are active at 160 °C, producing primarily CH 3 OH and alkanes. • High initial CH 3 OH selectivity over Cu/Mo 2 C and comparable activity to CuZnAlO x. [ABSTRACT FROM AUTHOR]

[Display omitted] • Ga atom with different coordination environments CN3, CN4 and CN5 were constructed on the Pd(1 1 1). • The reaction mechanism and selectivity for conversion of CO 2 to methanol (CTM) were systematic investigated. • The relationship between the reaction activity and coordination environments of Ga was revealed. • The potential importance of the 4-coordinated Ga atom was proposed for CTM. Methanol is easy to store compared to other gaseous hydrogenation products. Moreover, it can be further converted to other advanced hydrocarbons, so the conversion of CO 2 to methanol (CTM) is a promising reaction. PdGa bimetallic catalysts are candidate catalysts for CTM conversion, which can promote H spillover to the active site and react with adsorbed CO 2. However, the role of Ga atom in PdGa bimetallic catalysts and the underlying mechanism of CTM are still unclear at the molecular level. In this work, Ga atom with different coordination environments CN3, CN4 and CN5 were obtained on the Pd(1 1 1), and three reaction mechanisms of CTM on different catalysts are systematic investigated. Changes in the coordination environments of the Ga atom affected the adsorption configurations of HCOOH*, HCO*, and H 2 CO*, among others. Three catalysts have similar superior pathways, and the order of CO 2 reactivity is CN4 > CN3 > CN5. The PdGa bimetallic catalysts containing 4-coordinated Ga atom are proposed to be the ideal catalysts. We hope that the conclusions obtained can help understand the reasons for the outstanding reactivity and selectivity of CTM on PdGa bimetallic catalysts at the molecular level, and can provide some guidance for the design and development of high-performance bimetallic catalysts. [ABSTRACT FROM AUTHOR]

[Display omitted] • The catalytic performance of CuO/hydrangea-like CeO 2 is higher than that of others. • CuO/hydrangea-like CeO 2 enhances the dispersion of copper species. • CuO/hydrangea-like CeO 2 is beneficial to form oxygen vacancies and hydroxyl groups. • 4. Both m-HCOO* and bi-HCOO* are active intermediate species for CO 2 hydrogenation to CH 3 OH. A series of CuO catalysts supported on CeO 2 with different morphologies (nanorod, nanocube and hydrangea-like) were tested for the CO 2 hydrogenation into methanol. Remarkable morphology-dependent CuO-CeO 2 interaction was observed, which was associated with the types and concentrations of copper species. The best performance was obtained over the CuO/hydrangea-like-CeO 2 catalyst, giving CO 2 conversion of 15.6 % and methanol selectivity of 92.4 % at 260 °C and 3 MPa. The enhanced activity was due to the largest amount of small particle size of copper species, which was responsible for the facile activation of H 2. Additionally, the Cu2+-O v -Ce x species facilitated the generation of oxygen vacancies and hydroxyl groups, these two species favored formate production and further hydrogenation to methanol. Moreover, in situ diffuse reflectance infrared fourier transform spectroscopy (in situ DRIFTS) results revealed that the both monodentate formate (m-HCOO*) and bidentate formate (bi-HCOO*) were key and necessary intermediate of CO 2 hydrogenation to methanol. The proposed predominate reaction pathway was m-HCOO*→ b-*OCH 3 → CH 3 OH and the minor one was bi-HCOO* → t-*OCH 3 → CH 3 OH. [ABSTRACT FROM AUTHOR]

[Display omitted] • The ZrZnO x were determined by machine learning force field molecular dynamics. • Oxygen vacancies in ZrZnO x which was confirmed by in situ DRIFTS characterization. • For CO 2 reduction, the key intermediate is unstable at 593 K in the CO pathway. • The coordination number of Zn and Zr decreases in bulk and surface. Among the many catalysts used for CO 2 hydrogenation to methanol, ZnZrO x solid solution is a highly efficient catalyst. Although the reaction mechanism has been widely explored at 0 K using DFT, critical aspects such as the atomic structure of the solid solution and the stability of reaction intermediates during CO 2 reduction at experimental temperatures remain unclear. This study employs first-principle molecular dynamics (MD) simulations, FTIR and DRIFTS characterization to address these important questions. During the MD simulation, oxygen vacancies are formed in the system and same as the doped Zn atoms. The formation of oxygen vacancies was further confirmed by the Transmission FTIR and in situ DRIFTS. Due to the creating of oxygen vacancies, the coordination of Zn and Zr in the bulk is reduced to five and seven, respectively. And on the surface, their coordination is reduced to three、four and six、seven, respectively. Subsequently, the hydrogenation of CO 2 to methanol using the formate and CO* pathways was studied. In the formate pathway, all intermediates remained stable at 593 K. However, in the CO* pathway, we observe instability of key intermediates which also confirmed by transmission FTIR and in situ DRIFTS characterization. [ABSTRACT FROM AUTHOR]

[Display omitted] • A facile co-precipitation method is used to prepare catalysts with particles confined in cheap MOF. After calcination, more catalytic active sites could be exposed, which greatly improves the performance of the catalyst. • Compared with other methods, the co-precipitation method is simple, low-cost, and can better control the metal loading. At the same time, the problem of easy agglomeration of Cu nanoparticles and easy phase separation of Cu and ZnO at high temperature could be alleviated greatly. • The as-prepared Cu/ZnO x /ZrO 2 catalyst shows much better performance for CO 2 hydrogenation to methanol than the commercialized catalyst and catalyst prepared by double solvents method. The ternary Cu/ZnO/Al 2 O 3 catalyst is usually employed for producing methanol from syngas (CO/CO 2 /H 2) or from CO 2 hydrogenation in industry. However, this catalyst often suffers from the aggregation of Cu nanoparticles and the phase separation of Cu and ZnO. In this work, a highly efficient and stable catalyst (Cu/ZnO x /ZrO 2) for CO 2 hydrogenation to methanol is prepared via co-precipitation method with UiO-66 as structural template. Cu/Zn is effectively combined and encapsulated in the channels of UiO-66, which avoids the aggregation of metal particles. The ZrO 2 support derived from UiO-66 enhances the interaction between the support and Cu/Zn, and thus improves the catalytic performance significantly. This catalyst shows a high space–time yield of 216.7 g (MeOH) ·kg (cat) −1·h−1 at 260 °C, 4 MPa and GHSV = 12000 h−1. Furthermore, the catalyst shows good stability over a period of 50 h on stream. The performance of Cu/ZnO x /ZrO 2 is much better than that of commercial catalysts and most of catalysts previously reported. [ABSTRACT FROM AUTHOR]

Mitigation of anthropogenic CO2 emissions possess a major global challenge for modern societies. Herein, catalytic solutions are meant to play a key role. Among the different catalysts for CO2 conversion, Cu supported molybdenum carbide is receiving increasing attention. Hence, in the present communication, we show the activity, selectivity and stability of fresh-prepared β-Mo2C catalysts and compare the results with those of Cu/Mo2C, Cs/Mo2C and Cu/Cs/Mo2C in CO2 hydrogenation reactions. The results show that all the catalysts were active, and the main reaction product was methanol. Copper, cesium and molybdenum interaction is observed, and cesium promoted the formation of metallic Mo on the fresh catalyst. The incorporation of copper is positive and improves the activity and selectivity to methanol. Additionally, the addition of cesium favored the formation of Mo0 phase, which for the catalysts Cs/Mo2C seemed to be detrimental for the conversion and selectivity. Moreover, the catalysts promoted by copper and/or cesium underwent redox surface transformations during the reaction, these were more obvious for cesium doped catalysts, which diminished their catalytic performance.

In this article from Angewandte Chemie, researchers Jiafeng Yu, Anna Zimina, Jian Sun, and others discuss their findings on CO2 hydrogenation to methanol using single-site Zr catalysts. They were able to synthesize and stabilize SiO2-stabilized single-site Zr species using the flame spray pyrolysis method. This breakthrough allowed them to unlock a dual-channel pathway for the reaction, breaking the limitation between competitive formate and RWGS+CO-hydro pathways. The researchers achieved the highest overall methanol productivity when the two pathways struck a balance. [Extracted from the article]

In this work, the mesostructured Cu/AlZnO catalysts were prepared for the CO2 hydrogenation to methanol. Experimental results showed that the weight ratio of Al2O3 and ZnO affected the morphology of the mesoporous AlZnO supports and surface properties of the mesostructured Cu/AlZnO catalysts. The AlZnO‐9 (the Al2O3 mass within the AlZnO support was 90 wt%) with loose spongy porous structure and high surface area facilitated the Cu nanoparticle dispersion. Thus, the Cu/AlZnO‐9 catalyst showed higher exposed Cu surface area (SCu) and more exposed CO2 adsorption sites, which accelerated the CO2 conversion. Meanwhile, the ZnO added into catalysts increased the strength of surface basicity and the surface concentration of Zn species, which promoted the catalytic activity of CO2 hydrogenation to methanol. In addition, the well mesostructure heightened the stability of supported Cu catalyst due to the high dispersion of Cu nanoparticles. [ABSTRACT FROM AUTHOR]

Indium oxide supported iridium catalyst has been verified to be highly active and selective for CO 2 hydrogenation to methanol. In this work, zirconia is introduced into the Ir/In 2 O 3 system as a novel Ir/In 2 O 3 -ZrO 2 ternary catalyst. The solid solution generated between ZrO 2 and In 2 O 3 exhibits a strong electronic metal-support interaction with iridium, rendering the supported iridium species highly dispersed in a form of clusters. Thereout, an active interface between iridium and the solid-solution carrier is thus generated, on which electron transport is more feasible with a stronger CO 2 adsorption than that of on the Ir−In 2 O 3 interfacial site. Moreover, compared to Ir/In 2 O 3 , this ternary catalyst exhibits better catalytic activity as well as the stability. Density functional theory (DFT) simulations, combined with the in-situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) studies, further demonstrate the CO-hydrogenation pathway is the most favored for methanol synthesis, providing a rationale for the superior methanol selectivity of the Ir/In 2 O 3 -ZrO 2 catalyst during CO 2 hydrogenation. [Display omitted] • Zirconia greatly changes the electronic and structural property of Ir/In 2 O 3. • Ternary Ir/In 2 O 3 -ZrO 2 catalyst is highly active for CO 2 -to-methanol. • The addition of ZrO 2 induces intense SMSI phenomenon. • The In-Ov-Zr ensemble remarkably promotes the charge transfer. [ABSTRACT FROM AUTHOR]

Regulation of abundant Cu-ZnO interfaces in Cu/ZnO catalysts is critical to the thermal hydrogenation of CO 2 to methanol. Herein, Cu-ZnO interfaces were precisely regulated by depositing thin ZnO films on copper phyllosilicates (CuSiO 3) through atomic layer deposition (ALD) to prepare Cu/ZnO/SiO 2 composite catalysts (denoted as x ZnO/CuSiO 3 , x is the number of ALD cycles) for CO 2 hydrogenation to methanol. Interestingly, 5ZnO/CuSiO 3 exhibited much higher methanol selectivity of 68.1 % and methanol space-time yield (STY MeOH) of 0.39 g MeOH h−1g cat −1 toward CO 2 hydrogenation at 275 ℃ and 3 MPa, as compared to the pristine CuSiO 3 (38.1 % and 0.24 g MeOH h−1g cat −1), suggesting the significant role of Cu-ZnO interfaces. Compared to ZnO/CuSiO 3 (IM) prepared by the conventional impregnation method, 5ZnO/CuSiO 3 possessed much higher CO 2 conversion (13.8 % vs. 10.1 %) and methanol selectivity (68.1 % vs. 56.2 %). Furthermore, the catalytic activities of the prepared Cu/ZnO catalysts can be effectively regulated by changing the thickness of ZnO-ALD films, in which 5ZnO/CuSiO 3 showed the best catalytic activity. Various characterization methods were applied to demonstrate that ALD-ZnO was evenly laid flat on the surface of CuSiO 3 to construct abundant Cu-ZnO interfaces during the H 2 reduction treatment, which facilitated the dissociated activation of CO 2 and formation of CH 3 O* reaction intermediate and simultaneously inhibited the generation of CO byproduct. In addition, the density functional theory (DFT) calculations revealed the stronger interaction between Cu and ZnO over 5ZnO/CuSiO 3 , which implied more Cu-ZnO interfaces were generated for methanol production. Accordingly, this study verifies the significance of Cu-ZnO interfaces for CO 2 hydrogenation to methanol and provides a facile method to regulate Cu-ZnO interfaces by depositing ALD-ZnO films on the copper phyllosilicate precursor. [Display omitted] • Cu/ZnO catalysts were constructed by depositing ZnO films on copper phyllosilicates. • Fine regulation of Cu-ZnO interfaces can be realized by ZnO-ALD technology. • The existence of Cu-ZnO interfaces significantly improved the methanol selectivity. • Cu/ZnO prepared by ALD was much superior to that prepared by impregnation method. • Structure-activity relationships of catalysts were revealed by DRIFTS and DFT. [ABSTRACT FROM AUTHOR]

This contribution reports the impact of the reaction pressure (1, 10, 20 and 30 bar) on the deactivation of the commercial catalyst Cu/ZnO/Al 2 O 3 during the CO 2 hydrogenation to CH 3 OH. The best performance was obtained at 30 bar with ≈ 30 % of initial CO 2 conversion (X CO2) and CH 3 OH space-time-yield (STY MEOH) of 255 mg MeOH /g cat. h. Although the initial conversion decreased drastically the activity was kept along all the reaction time, ≈ 5 %. The analysis of fresh and post-reaction samples using X-ray Diffraction (XRD), Thermogravimetric Analysis (TGA), Electron Microscopy (SEM-FEG, STEM, HRTEM), and Raman Spectroscopy demonstrated profound microstructural changes, characterized by phase sintering, formation of Cu-aluminate, segregation of phases, an imbalance among Cu-species, as well as the presence of coke. As the catalyst Cu/ZnO/Al 2 O 3 has a particular microstructure, these modifications provoked the loss of the geometric configuration of the active sites, which might also originate a disturbance in the electronic interactions, resulting in activity loss. HRTEM and STEM image (dark field) of the passivated sample showed the presence of crystalline nanostructures (d < 4 nm) attributed to Cu0, surrounded by amorphous phases. STEM images of spent samples also reveals the development of hierarchical and elongated nanostructures spread on all the spent catalysts. This result foresees the co-existence of small nanoparticles (< 5 nm) with large ones in all the catalyst surface, corroborating XRD results. It is noteworthy that the hydrothermal environmental developed inside the reactor originated from the high pressure and the continuous H 2 O production, both which may favor the phase sintering and aluminate formation. [Display omitted] • Deep microstructural modifications of catalysts components. • Development of hierarchical nanostructures of Cu and Zn under reaction conditions. • Formation of inactive Cu-aluminates. • Segregation of phases ZnO and Al 2 O 3. • All the mentioned modifications led to a drop on the catalyst performance but still keeping the activity under TOS. [ABSTRACT FROM AUTHOR]

With the change of the global climate, the technology of hydrogenation of CO2 to methanol has attracted considerable attention all over the world. In this work, the hydrogenation of carbon dioxide to methanol over Cu/ZnO/ZrO2 catalysts is carried out at atmospheric pressure. The effect of process conditions on the catalytic performance is examined to determine the most effective conditions. The reaction kinetics are then investigated by using two Langmuir–Hinshelwood (L–H) kinetic models. The kinetic parameters are determined and statistical tests and residual analyses indicate that both kinetic models are reliable. However, the fitting effects for CO2 and CO are different between the two models. Moreover, the structural characteristics of the catalytic under different conditions are examined by TEM, XRD, and XPS. It can also be found that oxygen vacancies can facilitate the activation of carbon dioxide and the desorption of methanol during the reaction. The reactants and products undergo reactions in which oxygen migrates and reoxidation occurs with surface oxygen vacancies, resulting in an increase in the concentration of oxygen vacancies. [ABSTRACT FROM AUTHOR]

The InZrO x nanosheets had peculiar structure and plenty of oxygen defects, and displayed eminent performance in methanol synthesis from CO 2 and H 2. [Display omitted] • Two-dimensional InZrO x nanosheets were synthesized via a simple solvothermal method. • The InZrO x nanosheets had peculiar structure and plenty of oxygen defects. • The optimized ZrO 2 (30)-In 2 O 3 nanosheets showed ∼ 90 % methanol selectivity and an activity of 1.4 mmol g In -1h−1 at 180 °C. • Water as a clean solvent participated in the kinetic process of the reaction.. Synthesis of methanol via CO 2 hydrogenation is a very important reaction. In recent years, the In 2 O 3 based catalysts were proved to be a sort of promising catalysts to accelerate this reaction, which have aroused extensive attention. However, design of novel In 2 O 3 based catalysts that can efficiently produce methanol from CO 2 hydrogenation at low temperature is still in great need. Herein we fabricated the InZrO x nanosheets via a simple solvothermal method, which had peculiar surface structure and plenty of oxygen defects. The InZrO x nanosheets displayed excellent low temperature catalytic performance in a slurry reactor. The methanol selectivity (90 %) and activity (1.4 mmol g In -1h−1) were achieved at 180 °C, which are 2.3 and 1.6 times than that of the counterpart nanoparticles, respectively. Water as a clean and cheap reaction solvent played a crucial role, which participated in the kinetic process of the catalysis. The particular catalyst structure and the solvent effect of water accounting for the outstanding reaction results. [ABSTRACT FROM AUTHOR]

Workflow of the ML/SISSO-accelerated MSI degree evaluation on TM/In 2 O 3 -ZrO 2 substrate. The central focus of this study is to explore the metal-support interactions (MSI) between the metal species and the substrate in TM/In 2 O 3 -ZrO 2 catalysts, extracting data from theoretical calculations and employing machine learning (ML) and the SISSO methods to characterize the degree of MSI. Firstly, we select the CO 2 hydrogenation to methanol reaction as our research target. Subsequently, we conduct the density functional theory (DFT) calculations to investigate the formate pathway in defective In 2 O 3 -ZrO 2 models loaded with Cu, Ni, and Pd, extracting the activation energies of each respective rate-determining step as indicators for evaluating the reaction. Then, from an experimental and characterization perspective, we investigate the CO 2 conversion, methanol yield, and product selectivity at different temperatures, providing experimental evidence for our prior theoretical results. By combining computational and experimental data, we find a close correlation between the degree of MSI and the activation energy of the rate-determining steps, thus selecting activation energy as the target for prediction. Among a series of theoretical data, we select applicable thermodynamic features as potential descriptors and use scaling relations to identify two descriptors with high linear correlation, serving as the fundamental inputs for the SISSO method. Additionally, we attempt to incorporate all descriptors into ML methods for measurement and find that neural network (NN) method demonstrates the best predictive accuracy. In summary, this work provides a comprehensive approach spanning theoretical calculations, experimental validation and data analysis for MSI investigation, offering valuable analytical methods for CO 2 hydrogenation research. [Display omitted] • Methanol synthesis by CO 2 hydrogenation was studied by a multifaceted approach. • Ni-modified In 2 O 3 -ZrO 2 catalyst presented thermodynamic and kinetic superiority. • Two improvement strategies were proposed based on SISSO and ML methods. • An evaluation template for MSI degree between TM and carrier was established. Amidst the escalating concerns surrounding energy and environmental issues, the hydrotreatment of emitted CO 2 and conversion into C1 products, such as methanol, have emerged as a pivotal strategy for effective mitigation. Previous investigations have identified the potential of indium-zirconium oxide catalysts doped with transition metals (TMs) for methanol synthesis. However, a comprehensive understanding of the impact of different TM loadings on catalytic performance, as well as a quantitative elucidation of the degree of metal-support interaction (MSI) between TM and substrate, necessitates further exploration. A multifaceted approach covering density functional theory (DFT) calculation, experimental validation and machine learning (ML) analysis is employed in this study to elucidate the underlying principles of MSI influence on hydrogenation, culminating in two general models for predicting the activation energy representing the degree of MSI. Consistent findings from theoretical calculations and experimental results demonstrate that, in comparison to Cu and Pd, Ni doped In 2 O 3 -ZrO 2 catalyst shows superior performance both in thermodynamics and kinetics. This enhancement is attributed to the strong degree of MSI relationship between thermodynamically stable Ni and substrate, consequently leading to the enhancement in reducibility. Moreover, a three-layer framework is constructed to predict the activation energy in the formate pathway, which facilitates the evaluation of MSI degree in TM-loaded catalysts. To sum up, this work provides guidance for CO 2 hydrogenation studies and quantitative analysis of MSI, contributing to a heightened understanding of the interaction mechanisms in analogous research systems. [ABSTRACT FROM AUTHOR]

Fine-regulating the electronic state of metal species to enhance the catalytic activity has demonstrated to be an effective yet persistent challenge. The study introduces an innovative method for enhancing catalytic performance in hydrogenating CO 2 to methanol via modulating copper-support interactions through the adjustment of surface silanol groups. The developed Cu/S-1 catalyst exhibits outstanding results: 85% methanol selectivity and 8.0% CO 2 conversion under 240 °C and 3 MPa, while maintaining stability for over 200 h. This performance surpasses that of the Cu/SiO 2 catalyst. Analyses indicate that the higher presence of Cuδ+ species in Cu/S-1 is attributed to the silanol nests in S-1 zeolite, which can stabilize these species and prevent the further reduction. The study identifies Cuδ+ and Cu0 as active species for CH 3 OH and CO production, respectively. A higher Cuδ+/Cu0 ratio eventuates better CO 2 conversion and CH 3 OH selectivity. Copper-support interaction is a key to the exceptional stability of the catalyst. [Display omitted] • Catalytic performance could be tuned by metal-support interactions. • Silanol nests in S-1 zeolite stabilize Cuδ+ species. • High Cuδ+/Cu0 ratio on Cu/S-1 boosts the methanol selectivity. • Cuδ+ stabilizes the CH 3 O* species and suppresses CO formation. • The activity is stable for 200 h over the Cu/S-1 catalyst. [ABSTRACT FROM AUTHOR]

The escalating emission of CO 2 has caused a significant environmental impact. Hydrogenation of CO 2 to methanol stands as the primary objective in the liquid sunlight vision, aiming to mitigate CO 2 emissions. CuZn-based transition metal catalysts, known for their cost-effectiveness, demonstrate commendable catalytic performance at moderate temperatures and pressures, showcasing considerable potential in industrial applications. Consequently, a series of catalysts, composed of CuZn-based species supported on CeO 2 with strategically introduced appropriate oxygen vacancies, were meticulously prepared. It worth to noting that the size of Cu was precisely tuned, along with the enhanced ability to the adsorption and activation of CO 2 and H 2. As a result, the optimal CuZn/CeO 2 catalyst exhibits high methanol formation rate, recording at 433.4 g MeOH kg cat −1 h−1 with selectivity of 68.5% at 260 °C and 3 MPa. Simultaneously, the reaction path and the evolution of intermediates in CO 2 hydrogenation was thoroughly delineated. [Display omitted] • The activity of CO 2 hydrogenation to methanol was dependent on the size of Cu. • Cu nanoparticle at about 4.5 nm assure the optimal concentration of surface oxygen vacancies. • Cu size effect on the reaction mechanism of CuZn/CeO 2 catalyst was investigated. [ABSTRACT FROM AUTHOR]

[Display omitted] • Flower-like Co 3 O 4 -CuO-ZnO@ZIF-8 catalyst was synthesized by a two-step hydrothermal process. • The productivity of CH 3 OH over Co 3 O 4 -CuO-ZnO@ZiF-8 catalyst at 200 °C and 2 MPa was 449.71 mmol kg−1·h−1. • The good performance of the catalyst is attributed to the large specific surface area and abundant oxygen vacancies. Converting carbon dioxide (CO 2) into high-quality methanol to alleviate the energy crisis is a promising strategy. However, as a traditional catalyst for CO 2 hydrogenation to methanol, Cu/ZnO exhibits low CO 2 conversion and low methanol selectivity at low temperature. In order to improve the catalytic performance of CO 2 hydrogenation to methanol, Co 3 O 4 was introduced to form Co 3 O 4 -CuO-ZnO with flower-like structure, and then diamond-shaped ZIF-8 particles with large specific surface area and rich oxygen vacancies were synthesized on the surface of Co 3 O 4 -CuO-ZnO by hydrothermal method. A series of characterizations showed that the synthesis of ZIF-8 greatly increased the specific surface area of the catalyst. The oxygen vacancy is the site of CO 2 adsorption and activation, and stabilizes the reaction intermediate, which promotes the conversion of CO 2 and the formation of methanol. The introduction of Co promotes the formation of the alloy phase, enhances the interaction between the metals, makes the active center more dispersed, reduces the sintering of the catalyst, and thus exhibits better catalytic performance. Among co-precipitated CuO-ZnO, hydrothermal CuO-ZnO, CuO-ZnO@ZIF-8, Co 3 O 4 -CuO-ZnO and Co 3 O 4 -CuO-ZnO@ZIF-8 catalysts, Co 3 O 4 -CuO-ZnO@ZIF-8 exhibits the best catalytic performance (CO 2 conversion 16.06% and CH 3 OH selectivity 94.58%). Based on the above design, ZIF-8 and Co 3 O 4 synergistic CuO-ZnO catalyst effectively improved CO 2 conversion and CH 3 OH selectivity. [ABSTRACT FROM AUTHOR]

The behaviour of Pd deposited on Ga 2 O 3 and In 2 O 3 by CVI is compared for the hydrogenation of CO 2 to methanol. Ga 2 O 3 alone is inactive, but In 2 O 3 has good conversion, and selectivity as high as 89 % to CH 3 OH. The addition of Pd to the catalysts had relatively little effect for In 2 O 3 , but in contrast, the addition of Pd to Ga 2 O 3 , has a very big effect, inducing high activity and selectivity to methanol. Both oxides form Pd intermetallics - Pd 2 In 3 and Pd 2 Ga. However, for the In catalysts there is also a thick (∼3 nm) overlayer of the oxide, while for the Ga catalyst there was no such overlayer. Hence this is why addition of Pd to the Indium catalysts has relatively little effect on performance compared with Ga. Furthermore, the effect of Pd and Zn co-deposition on Ga₂O₃ and In₂O₃ was investigated, as well as the effect of the support morphology. Upon co-deposition of Pd and Zn, and after reduction, the Pd 2 In 3 catalyst remains phase stable, whereas the Pd 2 Ga alloy is replaced by PdZn, and is improved in methanol yield. [Display omitted] • Ga 2 O 3 is inactive for methanol synthesis from CO 2 and H 2 , but In 2 O 3 is active. • Pd added by CVI converts to Pd 2 In 3 on In 2 O 3 and Pd 2 Ga on Ga 2 O 3. • Alloy formation has little effect on In 2 O 3 for methanol synthesis, but a big effect on Ga 2 O 3 , making it more effective. • When Zn is added by CVI Zn outcompetes Ga and make the PdZn alloy, but it does not disrupt Pd 2 In 3. [ABSTRACT FROM AUTHOR]

Methanol synthesis by CO 2 hydrogenation is a key process in a sustainable methanol-based economy. Copper silicate (CuSiO 3) is considered as efficient for hydrogenation of C-O/C O bonds due to the synergistic effect from its unique dual-sites of Cu0-Cu+. However, it still confronts great obstacles of poor CO 2 conversion and low methanol selectivity. Herein, we designed a core-shell CuSiO 3 nanoreactor by hydrothermal method, the cavity of which between core and shell provided the reaction space for CO 2 and H 2 in CO 2 hydrogenation. Interestingly, the cavity of the nanoreactor could be tuned by the hydrothermal time, and the product selectivity altered accordingly. Intrinsically, because of the spatial restriction effect of reactants, the reactant especially hydrogen can be enriched on the concave surface of nanotubes and hollow spheres, leading to a favorable activity. Furthermore, the longer diffusion path derived from the increased cavity volume would cause a deep hydrogenation to CH 4. Based on this, we chose the nanoreactor with suitable cavity volume to impregnate copper nanoparticles to increased the active sites and regulate the ratio of Cu0/Cu+, achieving remarkable catalytic activity (the conversion of CO 2 is 19.7% and yield of methanol reaches up to ∼18%). Moreover, the copper nanoparticles could be anchored by the core and shells, contributed to an excellent stability of the catalytic system (>120 h). [Display omitted] • A unique structure Cu-based catalyst was constructed, achieving a record-high CH 3 OH yield. • The core shell structure could stabilize the Cu0 during the reaction. • Cu0 is primarily responsible for the activity, while Cu+ may facilitate conversion of intermediates. [ABSTRACT FROM AUTHOR]

• Methanol synthesis by CO 2 hydrogenation was studied using DFT and ML methods. • Spillover facilitated the activation of hydrogenation in relative and absolute terms. • SISSO promotes the prediction performance of machine learning models. • Four-level descriptor screening scheme is proposed for reference. With the increasing attention in environmental issues caused by CO 2 emissions, methanol conversion by CO 2 hydrogenation is an effective strategy to solve this existing energy dilemma. The rationale behind hydrogen spillover on methanol synthesis is unraveled via density functional theory (DFT) calculations in this work, furthermore, the activation energy of hydrogen transfer process as affected by spillover is also summarized in a general paradigm for facilitating the understanding of hydrogenation characteristics. The results demonstrate that the spillover strategy significantly facilitates the hydrogenation reaction by supplying available hydrogen adatoms. This effect is particularly pronounced during the stage when OH is formed directly at the substrate site and combines with H to produce H 2 O, leading to a substantial reduction in activation energy from the initial 3.74 eV to 0.78 eV. In addition, a comprehensive predictive model for the kinetic characteristics of hydrogen spillover process is established based on the machine learning algorithm and SISSO guidance. By employing the combined approach of SISSO and neural network, we have achieved a stable prediction performance for activation energy with R 2 = 0.99 and RMSE = 0.07 eV. The variable of C h g F S A u is identified as the most representative factor in describing the activation energy, demonstrating a correlation coefficient of -0.60. The extended multidimensional expression of Dist Au further highlights its close connection to activation energy, achieving an RMSE value of 0.41 eV. To sum up, this work elucidates the possible thoughts of catalyst design with spillover effect and gives reference for the description screening towards the chemical reactions similar to hydrogen spillover. This figure summarizes the descriptor screening strategy in predicting the activation energy of hydrogen transfer reactions on modified In 2 O 3 surfaces. It comprises four levels, each building upon the previous to enhance the model simplicity while ensuring accuracy. The first level represents the initial descriptors selected from energy, structure, and charge features, such as Dist Reactant , Mig H , C h g F S A u and Δ∅ Au + Reactant − Sub that exhibit high linear correlation with activation energy. The second level consists of comprehensive descriptors derived from the linear regression integration of the first level descriptors using SISSO method. This descriptor, denoted as SISSO 8 , exhibits the highest linear correlation with activation energy. The third level includes descriptors based on SISSO regression integration for C h g I S − F S R e a c t a n t , C h g I S R e a c t a n t , C h g I S − F S A u , C h g I S A u and C h g F S A u . This combination displays the highest linear correlation among single attribute descriptors, with an RMSE value of 0.28 eV. The fourth level involves descriptors established based on the SISSO regression equation for Dist Au. This method enables effective prediction of activation energy using only the single variable, with a RMSE value of 0.41 eV. [Display omitted] [ABSTRACT FROM AUTHOR]

PdCuZn/SiC catalysts were synthesized with different Pd:Cu:Zn molar compositions and tested in the hydrogenation of carbon dioxide to methanol at atmospheric pressure. Trimetallic catalysts were compared with the corresponding bimetallic ones (PdZn/SiC, CuZn/SiC and PdCu/SiC). Catalysts were characterized by N 2 adsorption/desorption, temperature-programed reduction (TPR), X-ray diffraction (XRD), transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS). The Pd 0 active sites were related to carbon monoxide formation via reverse water-gas-shift (RWGS), whereas the PdZn alloys catalyzed methanol synthesis. The role of copper in trimetallic catalysts was to inhibit the deposition of metallic palladium by forming a PdCu alloy that proved to be less active to CO formation. Moreover, the active sites of trimetallic catalysts were smaller and better dispersed than those of the corresponding bimetallic ones, probably due to a synergistic effect between the three metals. The catalyst with a molar composition of 37.5:12.5:50 Pd:Cu:Zn (mol.%) was selected as the most active for the methanol synthesis, as this sample showed the highest activity and selectivity to methanol. The role of copper was also shown to be crucial in trimetallic catalyst by comparing the best example with an equivalent bimetallic PdZn/SiC with a Pd:Zn molar ratio of 37.5:62.5. [ABSTRACT FROM AUTHOR]

[Display omitted] A dendritic PdCu/Ce 0.3 Zr 0.7 O 2 (PdCu/CZ-3) catalyst with uniform spherical morphology was prepared for boosting the catalytic performance of CO 2 hydrogenation to methanol (MeOH). The open dendritic pore channels and small particle sizes could reduce not only the diffuse resistance of reactants and products but also increase the accessibility between the active sites (PdCu and oxygen vacancy) and the reactants (H 2 and CO 2). More spillover hydrogen could be generated due to the highly dispersed PdCu active metals over the PdCu/CZ-3 catalyst. PdCu/CZ-3 can stimulate the generation of more Ce3+ cations, which is beneficial to produce more oxygen vacancies on the surface of the CZ-3 composite. Spillover hydrogen and oxygen vacancy could promote the formate and methoxy routes over PdCu/CZ-3, the primary intermediates producing MeOH. PdCu/CZ-3 displayed the highest CO 2 conversions (25.5 %), highest MeOH yield (6.4 %), highest PdCu-TOF MeOH (7.7 h−1) and superior 100 h long-term stability than those of other PdCu/Ce x Zr 1-x O 2 analogs and the reference PdCu/CeO 2 and PdCu/ZrO 2 catalysts. Density functional theory (DFT) calculations and in situ DRIFTS were performed to investigate the CO 2 − MeOH hydrogenation mechanism. [ABSTRACT FROM AUTHOR]