In this work we report the effects of support structural properties and its modification with some metal oxides modifiers on the catalytic behavior of Au catalysts in the total CO oxidation at 20 ◦C. Au catalysts were supported on mesoporous silica materials (MSM) having different structural properties: Channel-like (SBA-15), cage-like (SBA-16), hexagonal (HMS), and disordered (DMS-1) structures. The effect of the modifier was evaluated by comparison of the catalytic response of the SBA-15-based catalysts modified with MgO, Fe2O3, TiO2, and CeO2. The chemical, structural, and electronic properties of the catalysts were investigated by a variety of techniques (metal content analysis by ICP-OES, N2 physisorption, XRD, UV-vis DRS, DRIFTS of adsorbed CO and OH regions, oxygen storage capacity (OSC), HR-TEM, and XPS). The activity of calcined catalysts in the CO oxidation reaction were evaluated at steady state conditions, at 20 ◦C, atmospheric pressure, and when using, as feed, a 1%CO/1%O2/98% gas mixture. The work clearly demonstrated that all Au catalysts supported on the mesoporous silicas modified with metal oxides were more active than the Au/SBA-15 and Au/MgO reference ones. The support structural properties and type of dopant were important factors influencing on the catalyst behavior. Concerning the support textural properties, it was found that the HMS substrate with the wormhole-structure offers better porosity and specific surface area than their silica counterparts having channel-like (SBA-15), cage-like (SBA-16), and disordered (DMS-1) mesoporous structures. Concerning the effect of modifier, the best catalytic response was achieved with the catalysts modified with MgO. After activation by calcination at 200 ◦C for 4 h, the Au/MgO/HMS catalyst exhibited the best catalytic performance, which was ascribed to
the combined effects of the best structural properties, a large support oxygen storage capacity and homogeneous distribution of gold particles on the support (external and inner). Implications of the type of active sites (Au1+ or Au0), support structural properties and role of modifier on the catalytic
activity are discussed.., The authors would like to express their gratitude to FOFI-UAQ-2015 project (México), Spanish Ministry of Economy, Industry and Competitiveness (MINECO) by funding CTQ2016-76505-C3-1 project and Community of Madrid (Spain) for funding S2013/MAE-2882 project., Peer reviewed

This work studies the effect of the temperature in the solvothermal synthesis of CdS modified with Ag (Ag-CdS) over both the structure of CdS and the chemical state of the Ag species. The increase in the solvothermal temperature produces the evolution of the CdS nanostructures from nanoparticles of low crystallinity in coexistence with small nanocrystals with strong confinement effect to the formation of highly crystalline nanorods. The Ag species also change with the solvothermal temperature from Ag₂S species, formed at low temperature, to metallic species as the temperature increases. The photoactivity of the Ag-CdS samples is the result of the combination of three factors: crystallinity of the CdS structures, existence of small nanocrystals with strong confinement effect and the presence of segregated Ag₂S species. The Ag-CdS sample prepared at 120 °C shows the better efficiency for hydrogen production because it achieves the better combination of the aforementioned factors., The present work was performed within the research program supported by under the project and CAM within the S2013/MAE-288 project. This research was funded by MINECO (Spain), grant number CTQ2016-76505-C3-1-R. E. Soto would like to acknowledge MINECO for the FPI research grant., We acknowledge support by the CSIC Open Access Publication Initiative through its Unit of Information Resources for Research (URICI), Peer reviewed

[EN] Technological approaches which enable the effective utilization of CO for manufacturing value-added chemicals and fuels can help to solve environmental problems derived from large CO emissions associated with the use of fossil fuels. One of the most interesting products that can be synthesized from CO is methanol, since it is an industrial commodity used in several chemical products and also an efficient transportation fuel. In this review, we highlight the recent advances in the development of heterogeneous catalysts and processes for the direct hydrogenation of CO to methanol. The main efforts focused on the improvement of conventional Cu/ZnO based catalysts and the development of new catalytic systems targeting the specific needs for CO to methanol reactions (unfavourable thermodynamics, production of high amount of water and high methanol selectivity under high or full CO conversion). Major studies on the development of active and selective catalysts based on thermodynamics, mechanisms, nano-synthesis and catalyst design (active phase, promoters, supports, etc.) are highlighted in this review. Finally, a summary concerning future perspectives on the research and development of efficient heterogeneous catalysts for methanol synthesis from CO will be presented., The present investigation was funded by the research project CTQ2016-76505-C3-1 supported by the Spanish Ministry of Science, Innovation and Universities and the program BIOTRES-CM (S2018/EMT-4344) supported by the Comunidad Autónoma de Madrid. Elena Millán would like to acknowledge the FPI programme from Spanish Ministry of Science, Innovation and Universities for the research grant.

© 2020 by the authors., The performance of bifunctional hybrid catalysts based on phosphotungstic acid (H3PW12O40, HPW) supported on TiO2 combined with Cu-ZnO(Al) catalyst in the direct synthesis of dimethyl ether (DME) from syngas has been investigated. We studied the effect of the HPW loading on TiO2 (from 1.4 to 2.7 monolayers) on the dispersion and acid characteristics of the HPW clusters. When the concentration of the heteropoliacid is slightly higher than the monolayer (1.4 monolayers) the acidity of the clusters is perturbed by the surface of titania, while for concentration higher than 1.7 monolayers results in the formation of three-dimensional HPW nanocrystals with acidity similar to the bulk heteropolyacid. Physical hybridization of supported heteropolyacids with the Cu-ZnO(Al) catalyst modifies both the acid characteristics of the supported heteropolyacids and the copper surface area of the Cu-ZnO(Al) catalyst. Hybridization gives rise to a decrease in the copper surface area and the disappearance of the strong acidic sites typical of HPW nanocrystals, showing all hybrids similar acid sites of weak or medium strength. The activity of the hybrids was tested for direct DME synthesis from syngas at 30 bar and 250 °C; only the hybrids with HPW loading higher than 1.4 monolayers showed activity for the direct synthesis of DME, showing that the sample loaded with 2.7 monolayers of heteropolyacid had higher activity than the reference hybrid representative of the most widely applied catalysts based on the combination of Cu-ZnO(Al) with HZSM-5. In spite of the high activity of the hybrids, they show a moderate loss in the DME production with TOS that denotes some kind of deactivation of the acidity function under reaction conditions., The present investigation was performed within the research programs CTQ2016–76505-C3–1 and PID2019–111219RB-100 supported by the Spanish Ministry of Science, Innovation and Universities. The Autonomus Community of Madrid (CAM) is also gratefully acknowledged for funding BIOTRES-CM (P2018/EMT-4344) project. Elena Millán would like to acknowledge the FPI programme from Spanish Ministry of Science, Innovation and Universities for the research grant., Peer reviewed

© 2020 by the authors., The aim of this work is to study the influence of the sulphur source (elemental sulphur, thiourea and L-cysteine) in the solvothermal synthesis of Ag-CdS over its growth, structuration and state of Ag and how these changes influence on its photoactivity. The differences in the generation rate of the S2− from the sulphur sources during the solvothermal synthesis determine the nucleation and growth pathways of CdS affecting to the silver state and its incorporation into the CdS lattice. The hydrogen production on Ag-CdS photocatalysts decreases according the sequence: thiourea > elemental sulphur >> L-cysteine. The changes in the photoactivity of Ag-CdS samples are analysed in terms of the differences in the insertion of Ag+ into the CdS lattice, the formation of composites between CdS and Ag2S and the formation of CdS crystalline domains with strong confinement effect derived from the different sulphur source used in the solvothermal synthesis., The present work was performed within the research program supported by MINECO (Spain) under the projects CTQ2016-76505-C3-1-R and PID2019-1112119RB-100 and CAM within the BIOTRES-CM (S2018/EMT-4344) project. E. Soto would like to acknowledge MINECO for the FPI research grant., Peer reviewed

[EN] A simple ultrasonic radiation method was employed for the preparation of zinc and cadmium sulfide solid solution (ZnxCd1-xS; x = 0-0.25 wt.%) with the aim to investigate its efficiency for H2 production via a visible light-driven water-splitting reaction. The catalyst characterization by X-ray diffraction confirmed the formation of solid solution (ZnxCd1-xS) between CdS and ZnS phases. All catalysts exhibited hierarchical morphology (from SEM and TEM) formed by aggregated nanoparticles of ZnxCd1-xS solid solution with crystals showing mainly (111) planes of cubic CdS phase. The crystal size linearly decreased with an increase in Zn incorporation in the crystal lattice (from 4.37 nm to 3.72 nm). The ZnxCd1-xS photocatalysts showed a gradual increase in the H2 evolution, with an increase in the Zn concentration up to 0.2 wt.% making the most effective Zn0.2Cd0.8S catalyst toward H2 production. From the catalyst activity-structure correlation, it has been concluded that the twin-like CdS structure, the (111) plane and specific morphology are the main factors influencing the catalyst effectivity toward H2 production. All those factors compensated for the negative effect of an increase in band gap energy (Ebg) after ZnS incorporation into solid solution (from 2.21 eV to 2.34 eV). The effect of the catalyst morphology is discussed by comparing H2 evolution over unsupported and supported Zn0.2Cd0.8S solid solutions., This research was funded by FOFI-UAQ2018 project (México) and received partial funding from Spanish Ministry of Science, Innovation and Universities (CTQ2016-76505-C3-1 project).

The effect of introducing Ru impurities into the MoS2crystalline structure of the sulfided RuxMo(1-x)S2/SBA-15catalysts have been investigated using density functional theory (DFT) calculations and the catalyst character-ization by different techniques (chemical analysis (ICP-AES), temperature-programmed reduction (TPR), X-raydiffraction (XRD), N2physisorption, DRIFTS of adsorbed pyridine (DRIFTS-Py) and X-ray photoelectron spec-troscopy (XPS)). The catalyst activity was tested in the hydrodesulfurization (HDS) of dibenzothiophene (DBT)reaction carried out in a batch reactor,T= 320 °C and total H2pressure of 5.5 MPa. From electronic structureDFT calculations is was concluded that the 4d orbitals of both Mo and Ru played an important role in the catalystoptimization being the processes of transport and charge transference the most important ones. It was found thatthe enrichment with Ru, promotes a greater electronic participation (DOS at the Fermi level) of the differentatoms in the RuxMo(1-x)S2phase leading to metallization of the Mo ions. The catalyst activity in HDS of DBTreaction demonstrated a similar behavior to that of theoretical density of states (DOS) calculated via DFT. Allbimetallic systems presented the synergetic effect between Ru and Mo in the HDS of DBT reaction overRuxMo(1-x)S2/SBA-15 catalysts. The highest activity observed for Ru content ofx= 0.4 was consistent with theoretical results predicting that the optimum DOS contributions should be aroundx= 0.44. The most activeRu0.4Mo0.6S2/SBA-15 exhibit the best hydrogenation properties linked with the Ru-induced metallization of Moions in the Ru0.4Mo0.6S2phase. This catalyst showed two-fold higher hydrogenation properties than CoMoS/γ-Al2O3reference catalyst. The linear dependencies of initial activity on Brønsted-to-Lewis acidities ratio (fromDRIFT-Py) and total metal surface exposure (from XPS) were observed., The authors acknowledge the Consejo Nacional de Ciencia yTecnología (CONACyT) for the financial support of CONACYT (Projects117373 and 152012). D.H. Galvan and B. Pawelec acknowledges Supercómputo UNAM through project No. LANCAD-UNAM-DGTIC-041and CTQ2016-76505-C3-1 project supported by the Spanish Ministry of Economy, Industry and Competitiveness (MINECO), respectively.

This contribution describes the modification in the structure and activity of Cu/ZnO catalyst in the methanol synthesis reaction induced by the co-modification with a low amount of Al and Ga (Al+Ga=3% atom). To elucidate the effect of the co modification, the catalysts were characterized by means of variety of techniques (XRD, N2 physisorption, FTIR, TGA, TEM, TPR and N2O chemisorption) and tested in the methanol synthesis
reaction carried out in a flow reactor at 250 °C and total pressure of 3 MPa using syngas. The combined characterization and activity tests demonstrated that the co-doping with Al and Ga affects the structure and activity of Cu/ZnO catalysts in a different manner depending on the Al/Ga ratio used. The best catalyst co-loaded with Ga and Al in equal amount shows an improvement in the activity for methanol synthesis respect to the activity obtained on catalysts individually loaded with Al and Ga. The difference in the activity of the samples co-loaded with Al and Ga normalized by N2O chemisorption point to a different participation of the copper surfaces in combination with the defect sites of ZnO depending on the Al and Ga loading., The present investigation was performed within the research program CTQ2016-76505-C3-1 supported by the Spanish Ministry of Science, Innovation and Universities. Elena Millán would like to acknowledge the FPI programme from Spanish Ministry of Science, Innovation and Universities for the research grant.

© 2021 by the authors., Dimethyl ether (DME) is a versatile raw material and an interesting alternative fuel that can be produced by the catalytic direct hydrogenation of CO2. Recently, this process has attracted the attention of the industry due to the environmental benefits of CO2 elimination from the atmosphere and its lower operating costs with respect to the classical, two-step synthesis of DME from syngas (CO + H2). However, due to kinetics and thermodynamic limits, the direct use of CO2 as raw material for DME production requires the development of more effective catalysts. In this context, the objective of this review is to present the latest progress achieved in the synthesis of bifunctional/hybrid catalytic systems for the CO2-to-DME process. For catalyst design, this process is challenging because it should combine metal and acid functionalities in the same catalyst, in a correct ratio and with controlled interaction. The metal catalyst is needed for the activation and transformation of the stable CO2 molecules into methanol, whereas the acid catalyst is needed to dehydrate the methanol into DME. Recent developments in the catalyst design have been discussed and analyzed in this review, presenting the different strategies employed for the preparation of novel bifunctional catalysts (physical/mechanical mixing) and hybrid catalysts (co-precipitation, impregnation, etc.) with improved efficiency toward DME formation. Finally, an outline of future prospects for the research and development of efficient bi-functional/hybrid catalytic systems will be presented., The present investigation was performed within the research programs CTQ2016-76505-C3-1 and PID2019-111219RB-100 supported by the Spanish Ministry of Science, Innovation and
Universities. The Autonomous Community of Madrid (CAM) is also gratefully acknowledged for funding the BIOTRES-CM (P2018/EMT-4344) project. Elena Millán would like to acknowledge the
FPI program from the Spanish Ministry of Science, Innovation and Universities for the research grant., Peer reviewed

This work is dedicated to the study of the effect of the synthesis conditions (drying and calcination) of sulfated zirconia on the final catalytic behavior of bifunctional composite catalysts prepared by the physical mixing of the sulfated zirconia (methanol dehydration catalyst) with Cu/ZnO/Al2O3 (CZA; methanol synthesis catalyst). The main objective was to optimize the CZA-ZrO2/SO42− composite catalyst for its use in the direct production of dimethyl ether (DME) from syngas. Sulfated zirconia aerogel (AZS) and xerogel (XZS) were prepared using the sol–gel method using different solvent evacuation conditions and calcination temperatures, while the Cu-ZnO(Al) catalyst was synthesized using the coprecipitation procedure. The effectivity of CZA-ZrO2/SO42− composite catalysts for the direct production of dimethyl ether (DME) from syngas was evaluated in a flow reactor at 250 °C and 30 bar total pressure. The characterization of the sulfated zirconia aerogels and xerogels using different techniques showed that the mesoporous aerogel (AZS0.5300) exhibited the best textural and acidic properties due to the gel drying under supercritical conditions and calcination at 300 °C. As a result, the composite catalyst CZA-AZS0.5300 exhibited seven times higher DME production than its xerogel-containing counterpart (364 vs. 52 μmolDME·min−1·gcat−1). This was attributed to its well-matched metal surface, mesoporous structure, optimal crystallite size and, most importantly, its higher acidity., he authors gratefully acknowledge the financial support provided by the Tunisian Ministry of Higher Education and Scientific Research and by the research programs PID2019–111219RB-100 and PID 2022-143180OB-I00 supported by the Spanish Ministry of Science, Innovation and Universities. E.M.O. and C.Q.R. would like to acknowledge the FPI programme of the Spanish Ministry of Science, Innovation and Universities for their research grants (PRE2020-094027 and BES-2017-080240)., Peer reviewed