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Owing to the intrinsic nature of the uniformed topologies and ultrasmall Zr6 nodes of Zr-MOFs, herein, we employed Zr-MOFs (UiO-66 and UiO-67), as opposed to the support of traditional ZrO2, to prepare the Pd catalysts for toluene degradation. Compared with the catalysts of Pd/UiO-66 and Pd/ZrO2, Pd/UiO-67 catalyst boosted an excellence catalytic performance for toluene degradation, giving the lowest T90% value of 235 °C with long-term stability. With the assisting of the cavity confinement of Zr-MOFs, Pd nanoparticles are prone to be encapsulated in the 3D frameworks of Zr-MOFs, and the bigger micropores of UiO-67 are more conducive to the formation of larger Pd nanoparticles. The in situ FT-IR results further declared that although the active sites are partly sacrificed due to the larger Pd nanoparticles formed in UiO-67, the stable adsorbed toluene on Pd/UiO-67 boosted the quick degradation of toluene in the reaction interval even without undergoing intermediate processes of benzoate and benzaldehyde. UiO-66, UiO-67 and ZrO2 were employed to prepare the Pd catalysts for toluene degradation, Pd/UiO-67 catalyst boosted an excellence catalytic performance with long-term stability. [ABSTRACT FROM AUTHOR]

A series of ZnO/ZrO2 catalysts were synthesized by the precipitation method. The effect of different precipitation modes on the physicochemical properties of the ZnO/ZrO2 catalysts for CO2 hydrogenation to methanol was investigated. The catalysts were characterized by X-ray diffraction (XRD), N2 adsorption–desorption, transmission electron microscopy (TEM), temperature programmed desorption of CO2 (CO2-TPD), temperature programmed reduction of H2 (H2-TPR), and X-ray photoelectron spectroscopy (XPS). The results showed that the catalyst of ZnO/ZrO2 prepared by the concurrent precipitation method had more CO2 adsorption sites, resulting in its higher CO2 conversion. While the stepwise precipitation mode increased the surface oxygen content of ZnO/ZrO2, which enhanced the methanol selectivity. Overall, the ZnO/ZrO2 prepared by the concurrent precipitation mode exhibited a highly competitive efficacy for CO2 hydrogenation, giving a methanol selectivity of 81.4% with a CO2 conversion of 5.1% at 280 ℃ and 3 MPa, and the methanol yield reached 4.2%. The effect of different precipitation modes on the physicochemical properties of the ZnO/ZrO2 catalysts for CO2 hydrogenation to methanol was investigated, and the ZnO/ZrO2 prepared by the concurrent precipitation mode exhibited a highly competitive efficacy for CO2 hydrogenation. [ABSTRACT FROM AUTHOR]

Maintaining high conversion under the premise of high oxygenates selectivity in syngas conversion is important but a formidable challenge in Rh catalysis. Monometallic Rh catalysts provide poor oxygenate conversion efficiency, and efforts have been focused on constructing adjacent polymetallic sites; however, the one‐pass yields of C2+ oxygenates over the reported Rh‐based catalysts were mostly <20 %. In this study, we constructed a monometallic Rh catalyst encapsulated in UiO‐67 (Rh/UiO‐67) with enhanced proximity to dual‐site Rh1,2‐Rhn ensembles. Unexpectedly, this catalyst exhibited high efficacy for oxygenate synthesis from syngas, giving a high oxygenate selectivity of 72.0 % with a remarkable CO conversion of 50.4 %, and the one‐pass yield of C2+ oxygenates exceeded 25 %. The state‐of‐the‐art characterizations further revealed the spontaneous formation of an ensemble of Rh single atoms/dimers (Rh1,2) in the proximity of ultrasmall Rh clusters (Rhn) confined within the nanocavity of UiO‐67, providing adjacent Rh+‐Rh0 dual sites dynamically during the reaction that promote the relay of the undissociated CHO species to the CHx species. Thus, our results open a new route for designing highly efficient Rh catalysts for the conversion of syngas to oxygenates by precisely tuning the ensemble and proximity of the dual active sites in a confined space. [ABSTRACT FROM AUTHOR]

UiO-66 and its modified forms (UiO-66-NH2 and UiO-66-OH) were used as supports to prepare Rh–Mn catalysts by using a co-impregnation method, and their catalytic activities were investigated for the direct synthesis of ethanol-based C2+ oxygenates from CO hydrogenation. The catalysts were comprehensively characterized using N2 sorption, XRD, XPS, DRIFT, and TPSR analyses. The structural and textural properties of the catalysts clearly show that Rh and Mn are highly dispersed in the pores of MOFs, but the order of the original structure is partially sacrificed due to the loading of metals and the synergistic effect of Rh, Mn, and Zr would be influenced by various functional groups present in UiO-66. On combining both in situ FT-IR and TPSR analyses, it is confirmed that the higher number of active sites of Rh0 on RM/UiO-66 promotes the CO dissociation ability and hydrogenation rate, which result in its best catalytic activity with the highest yield of C2+ oxygenates, 197.3 g (kg h)−1. [ABSTRACT FROM AUTHOR]

A series of highly ordered microporous Ce-based metal-organic frameworks (MOFs) were synthesized as the precursors for catalyst construction. The corresponding Ru catalysts were prepared by Ru impregnation on the derived CeO 2 by pyrolysis of Ce-MOF, and investigated for the CH 4 synthesis via CO 2 hydrogenation. Among the catalysts, Ru catalyst supported on the CeO 2 -B derived from Ce-BDC exhibited a highly competitive efficiency for CO 2 methanation, giving a CH 4 selectivity of 100% with a CO 2 conversion of 62% at 275 °C and 0.1 MPa, and the CH 4 productivity reached 0.49 mol/(mol Ru ·h). Characterization results revealed that more oxygen vacancies and corresponding surface oxygen species formed on the surface of CeO 2 -B derived from Ce-BDC caused to the stronger interaction between Ru and CeO 2 -B, which promoted the CO 2 adsorption and hydrogenation capacity of the catalyst, resulting in its better catalytic property. In situ diffuse reflectance infrared Fourier transform (DRIFT) studies further revealed that the route of HCOO* into CH 4 is a more competitive way of CO 2 hydrogenation to CH 4. [Display omitted] • CeO 2 supported Ru catalysts were constructed based on the heat-treatment strategy of Ce-MOFs. • Ru catalyst supported on CeO 2 -B exhibited a highly competitive efficacy for CO 2 methanation. • More oxygen vacancies and surface oxygen species were formed on CeO 2 -B surface. • The stronger interaction between Ru and CeO 2 -B promoted the CO 2 adsorption and hydrogenation. • The route of HCOO* into CH 4 is a more competitive way of CO 2 hydrogenation to CH 4. [ABSTRACT FROM AUTHOR]

[Display omitted] • Fe and Na were found to be the most efficient promotors of Rh/CeO 2 catalyst for CO 2 hydrogenation to ethanol. • The optimized catalyst of 2Rh0.5Fe0.5Na/CeO 2 obtains a high ethanol selectivity of 29.8 % with a CO 2 conversion of 13.0 %. • The modification of Fe and Na promote the formation of Rh+ species, enhancing capacities of CO 2 adsorption and dissociation. • The Rh active sites synergized with Fe and Na can stabilize the adsorbed species of m-CO 3 2− and CO 3 H−. • The generation of HCOO*, CH 3 O* and CH 3 CH 2 O* intermediates promotes the ethanol formation. Rh catalyst is investigated as a strong candidate for CO 2 hydrogenation to ethanol, but it is still challenging because of the poor conversion efficiency. Here, by screening the promotors systematically and varying the amounts of components simultaneously, the optimized catalyst of 2Rh0.5Fe0.5Na/CeO 2 was found to highly efficient catalytic CO 2 hydrogenation to ethanol, giving a high ethanol selectivity of 29.8 % with a superior CO 2 conversion of 13.0 % at 250 °C, 3 MPa, and the ethanol productivity reached 116.7 mmol·g Rh −1·h−1. Characterization results revealed that the modification of Fe and Na, can promote the dispersion of Rh and the formation of Rh+ species, enhancing the capacities of CO 2 adsorption and dissociation. In situ DRIFT experiment illuminated that the Rh active sites synergized with Fe and Na can stabilize the adsorbed species of m-CO 3 2− and CO 3 H−, and promote the generation of HCOO* and CO* intermediates, which can be provided to couple with the CH x species, resulting in the high efficacy for ethanol synthesis from CO 2 hydrogenation. [ABSTRACT FROM AUTHOR]

The effect of iron promoter on the catalytic properties of Rh-Mn/UiO-66-drived catalyst was investigated by syngas conversion. The appropriate addition of Fe can enhance the Rh-Fe interaction, resulting in the enhancement of CO dissociation ability and strength of the Rh-CO bond, which should be responsible for the higher CO conversion and selectivity of C 2 + oxygenates. [Display omitted] • Fe-promoted Rh-Mn/UiO-66-drived catalysts were investigated by syngas conversion. • The Rh-Fe interaction can promote the reduction of Rh active sites. • The Rh0-rich state can enhance CO dissociation ability and Rh-CO bond strength. The effect of iron promoter on the catalytic performance of Rh-Mn/UiO-66-drived catalyst was studied by syngas conversion. The catalysts were completely characterized by means of X-ray diffraction (XRD), N 2 sorption, transmission electron microscopy (TEM), X-ray photoelectron spectra (XPS), diffuse reflectance infrared Fourier transform spectra (DRIFTS), and temperature-programmed surface reaction (TPSR). When the amount of Fe doping reached 0.3 wt%, the catalyst has the excellent catalytic activity with the highest C 2 + oxygenates yield of 300.1 g/(kg·h). The results indicated that the appropriate addition of iron can enhance the Rh-Fe interaction, which promote the reduction of Rh active sites. The Rh0-rich state would be observed on the catalysts doped by the appropriate amount of Fe, resulting in the enhancement of CO dissociation ability and strength of the Rh-CO bond, which should be responsible for the higher conversion rate and selectivity of C 2 + oxygenates. [ABSTRACT FROM AUTHOR]

• La-modified NiAl catalysts derived from hydrotalcite-like precursor were prepared. • Excellent low-temperature activity was obtained over the La-modified NiAl catalyst. • The stability of NiAl catalyst was greatly improved with the modification of La. • La improves the dispersion of active Ni, promotes the reducibility of NiO. • The introduction of La can inhibit the agglomeration of Ni particles. A series of La-modified NiAl catalysts based on the hydrotalcite-like precursor were prepared by the ethylene glycol solvothermal method and used for CO 2 methanation. As a dopant, La3+ was used for replacing Al3+. Under the condition of T = 225 °C, WHSV = 24000 mL/(g∙h), P = 1.0 atm, CO 2 conversion reaches 82.3 % as the substitution degree is 0.1. The characterization results show that the introduction of La promotes the dispersion of active Ni, improves the redox performance of the catalyst and also facilitates the adsorption and activation of CO 2 by increasing the basic sites, thus improving the catalytic activity. Moreover, the thermal stability of the catalyst was also significantly improved in the presence of La because the introduction of La inhibited the agglomeration of Ni particles. [ABSTRACT FROM AUTHOR]

• LaNi x Fe 1- x O 3 (x = 0, 0.2, 0.4, 0.6, 0.8, 1.0) as photothermal catalysts reduction of CO 2 with H 2 O vapor to CH 4 and CH 3 OH. • The solid solutions possesses lead to a significant modification with the quantity of oxygen vacancies and band gaps. • LaNi 0.4 Fe 0.6 O 3 compound exhibits the best photothermal catalytic performance. LaNi x Fe 1- x O 3 perovskite compounds (x = 0, 0.2, 0.4, 0.6, 0.8, 1.0) were successfully synthesized by a sol-gel combustion method. The crystal structure, morphology, BET surface area, oxygen vacancies, band gap and catalytic properties of the catalyst were characterized in detail. The results showed that LaNi 0.4 Fe 0.6 O 3 compound exhibits the best photothermal catalytic performance. Under the same catalytic conditions (350 ℃ + Vis-light), CH 4 and CH 3 OH yields are about 3.5 and 4.0 times, 1.8 and 2.1 times of that of LaFeO 3 and LaNiO 3. It was found that all the solid solutions possesses better catalytic properties than the pure end compounds. The doping of Ni lead to a significant modification with the quantity of oxygen vacancies and band gaps. These findings may further broaden the materials scope for photothermal conversion of CO 2 and H 2 O. [ABSTRACT FROM AUTHOR]

In this study, a transition metal-based perovskite oxide catalyst with high CH 3 OH yield was successfully developed. The A-site substitution by Pr3+ in La 1-x Pr x Mn 0.6 Ni 0.4 O 3-δ can effectively adjust the activity of the perovskite catalysts for the direct conversion of CO 2 and H 2 O into hydrocarbon fuels, especially CH 3 OH. Based on the designed photo-thermo synergetic photosynthesis strategy, the first hour CH 3 OH yield of La 1-x Pr x Mn 0.6 Ni 0.4 O 3-δ reached 3.97 mmol g−1, while only 0.24 μmol g−1 under normal photocatalysis mode. The synergistic photo-thermo catalysis was demonstrated to be a promising strategy for the future artificial photosynthesis development. [Display omitted] • In this study, a transition metal-based perovskite oxide catalyst with high CH 3 OH yield was developed. • The total carbon conversion rate can reach 6.73% with photo-thermo photosynthesis method. • The catalyst of La 1-x Pr x Mn 0.6 Ni 0.4 O 3-δ possesses abundant oxygen vacancies as active sites of CH 3 OH. [ABSTRACT FROM AUTHOR]

Abstract: SiO2, TiO2 and SiO2–TiO2 mixed oxide were synthesized by sol–gel method and used as supports for Rh-based catalysts. The effect of support on the performance of Rh-based catalysts for C2-oxygenates synthesis from syngas was investigated by XRD, N2 adsorption-desorption, FT-IR, H2-TPD, H2-TPR and TPSR techniques. The results indicated that SiO2–TiO2 supported catalyst had higher dispersion of Rh and thus more Rh+ sites, better capability for CO adsorption and dissociation, and moderate ability for hydrogenation. As a result, SiO2–TiO2 supported Rh-based catalyst exhibited higher activity and C2 oxygenates selectivity compared with counterparts supported on TiO2 and SiO2. [Copyright &y& Elsevier]