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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]

A series of Cu-ZnO-ZrO2 (CCZ) catalysts were prepared by the solvothermal method with different solvothermal times (1 h, 3 h, 6 h, and 12 h). The physicochemical properties of these catalysts and the catalytic performance for CO2 hydrogenation to methanol were studied. The highest methanol yield was achieved when the solvothermal time was 6 h (CCZ-6). Furthermore, we found that the copper surface area (SCu) increases and then decreases with an increase in the solvothermal time and that there is a strong correlation between the methanol yield and the SCu. This research highlights the crucial influence of the solvothermal time on the structure and catalytic behavior of Cu-ZnO-ZrO2 catalysts, providing a valuable reference for the development of efficient catalysts. [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]

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]

A series of Mn3Co16Ox composite oxides catalysts were fabricated via a solid-phase synthesis using different manganese precursors (namely manganese acetate (A), nitrate (N), and sulfate (S)). It has been demonstrated that the obtained catalysts presented variable catalytic activities for CO oxidation and remarkable diversity of physicochemical properties closely depending on the manganese precursors. In detail, the catalytic activity and catalytic durability for CO oxidation under humid conditions generally followed a descending order of Mn3Co16Ox-A > Mn3Co16Ox-N > Mn3Co16Ox-S. The optimum catalytic performance of Mn3Co16Ox-A was predominantly attributed to its larger specific surface area, significantly higher low-temperature reducibility and lattice oxygen mobility, and more plentiful oxygen vacancies. [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]

• MCF silica supported CuO CeO 2 catalysts were used for CO oxidation. • CD-assisted co-impregnation was superior to traditional co-impregnation. • Catalyst prepared by CD-assisted method has high activity and stability. • Kind of CD used in preparation has no distinct effect on catalyst activity. • Amount of CD used in preparation has no distinct effect on catalyst activity. A CuO-CeO 2 /MCF catalyst was prepared by cyclodextrin-assisted co-impregnation (CC/M-CD). For comparison, a reference catalyst was prepared by traditional wet impregnation (CC/M). The catalysts were characterized by ICP-OES, XRD, Raman, N 2 -physisorption, TEM, EDS mapping, XPS, in situ DRIFTS, H 2 -TPR, and CO-TPD. The results show that Cu and Ce species of the CC/M-CD catalyst disperse more homogeneously, and the CC/M-CD catalyst has a larger surface area, more amounts of Cu+ and Ce3+ species, enhanced interaction between CuO and CeO 2 , and thus exhibits higher catalytic activity in CO oxidation. Additionally, the kind and amount of cyclodextrin used in the impregnating solutions have no distinct effect on the activity of CC/M-CD prepared by the cyclodextrin-assisted co-impregnation. [ABSTRACT FROM AUTHOR]

A series of WO 3 modified CuO-ZnO-ZrO 2 mixed oxides with different WO 3 contents (0–20 at.%) were prepared by co-precipitation method and used as catalyst for methanol synthesis from CO 2 hydrogenation. The effects of WO 3 content on the physicochemical and catalytic properties of the CuO-ZnO-ZrO 2 -WO 3 catalysts were investigated by X-ray diffraction, X-ray photoelectron spectra, temperature-programed reduction of hydrogen, temperature-programed desorption of CO 2 , N 2 adsorption and desorption, reactive N 2 O adsorption, and activity testing. The results indicated that both CO 2 conversion and methanol selectivity of the CuO-ZnO-ZrO 2 catalyst was enhanced by the addition of small amounts (2 and 5 at.%) of WO 3 . However, the activity was significantly decreased by the addition of excessive WO 3 (20 at.%). The activity was closely related to the specific surface area of metallic Cu ( S Cu ), amount of weak basic sites, and reducibility of the catalyst. [ABSTRACT FROM AUTHOR]

• CuO-Ce x Zr 1-x O y are prepared via a facile surfactant-assisted grinding method. • CuO-Ce 0.7 Zr 0.3 O y exhibits the highest activity and moisture resistance. • Activity is related to contents of highly dispersed CuO and oxygen vacancies. • CO oxidation catalyzed by CuO-Ce x Zr 1-x O y mainly follows the L-H mechanism. • CuO-Ce 0.7 Zr 0.3 O y exhibits excellent stability and adaptability to space velocity. A series of CuO-Ce x Zr 1-x O y mixed oxides with different Ce contents were prepared via a facile surfactant-assisted grinding method, and their catalytic activity for CO oxidation under dry or moist atmosphere were investigated. The results indicate that the catalyst with a Ce content (x) of 0.7 in Ce x Zr 1-x O y (CuCe 0.7 Zr 0.3) exhibited the best activity under both dry and moist atmospheres, with the temperatures corresponding to CO conversion of 90 % (T 90) at a space velocity of 18000 mL/(g cat · h) being 90 and 120 °C, respectively. Combing with the physicochemical properties of the catalysts obtained by multiple characterization techniques such as ICP-OES, XRD, Raman, N 2 sorption, XPS, in situ DRIFTs, H 2 -TPR, O 2 -TPD and CO-TPD, the high activity of the CuCe 0.7 Zr 0.3 catalyst can be mainly attributed to the existence of large amounts of highly dispersed CuO x species and oxygen defect sites. [ABSTRACT FROM AUTHOR]

• Activation temperature exerts important effect on CuO-CeO 2 catalyst. • The catalyst activated at 550 °C exhibits superior activity and moisture resistance. • Activity is closely related to contents of Cu+ species and oxygen vacancies. • Dispersed CuO with strong interaction with CeO 2 exhibits good moisture resistance. • Bulk CuO with no or weak interaction with CeO 2 exhibits poor moisture resistance. Development of a highly efficient Cu-based catalyst for low-temperature CO oxidation under moisture condition remains a grand challenge. In this paper, effect of activation temperature (350–800 °C) on catalytic performance of CuO-CeO 2 , prepared by facile one-step solvothermal synthesis, in CO oxidation was investigated, and the catalysts' physicochemical properties were studied by TG-DSC, ICP-AES, N 2 sorption, XRD, TEM, Raman spectroscopy, XPS, in-situ DRIFTS, H 2 -TPR, CO-TPD, and O 2 -TPD. It was found that activation at 550 °C is beneficial for the interaction between CuO and CeO 2 , leading to the formation of more Cu+ species and oxygen vacancies advantageous for improving the catalytic activity. Activation at 800 °C, nevertheless, would weaken the interaction between CuO and CeO 2 due to the sintering of CuO and CeO 2 , thus decreasing the catalytic activity and moisture resistance. Interestingly, no deactivation was observed over the optimal catalyst (activated at 550 °C) after 50 h testing at a low temperature of 87 °C (at which 90% CO conversion was obtained), even when 4.2% water vapor was added into the feed gas. [ABSTRACT FROM AUTHOR]

HZSM-5 zeolites modified with various alkaline earth oxides (MgO, CaO, and BaO) were prepared by using impregnation and mixed physically with Cu/ZnO/Al2O3 to perform the direct synthesis of dimethyl ether (DME) from syngas in a pressurized fixed-bed under continuous flow conditions. The results indicated that the modification effectively enhanced the DME selectivity; MgO and CaO are more effective modifiers than BaO and they improved the DME selectivity up to 67 % as compared to only 54 % over the parent HZSM-5. Moreover, the catalyst prepared from magnesium nitrate exhibits higher DME selectivity than those prepared from magnesium acetate and chloride. The enhancement in the DME selectivity resulted from the effective suppression of hydrocarbon and CO2 formation, which can be attributed to the significant decline in the amount of strong acid sites of the HZSM-5 zeolite resulting from the modification. [ABSTRACT FROM AUTHOR]

A tandem cycle ride: The catalytic reaction mechanism of CO oxidation over Pd‐Cu‐Clx/γ‐Al2O3 is proposed based on DFT studies. There are two catalytic cycles in the CO oxidation process, the palladium cycle (— (green)) and the copper cycle (— (red)). [ABSTRACT FROM AUTHOR]

Ni-modified Ag/SiO2 catalysts containing 0~3 wt.% Ni were obtained by impregnating Ni species onto Ag/SiO2 followed by calcination and reduction. The catalysts' performance in the hydrogenation of dimethyl oxalate (DMO) to methyl glycolate (MG) was tested. Ag-0.5%Ni/SiO2 showed the highest catalytic activity among these catalysts and exhibited excellent catalytic stability. The effects of the Ni content on the structure and surface chemical states of catalysts were investigated by XRF, N2-sorption, XRD, TEM, EDX-mapping, FT-IR, H2-TPR, UV–vis, and XPS. The better catalytic activity and stability of Ni-modified Ag/SiO2 (versus Ag/SiO2) are ascribed to the improved dispersion of active Ag species as well as the higher resistance to the growth of Ag particles due to the presence of Ni species. [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]

Abstract: A series of HZSM-5 zeolites modified with various contents of antimony oxide (0–30wt.%) were prepared by solid state ion reaction at 500°C, and the acidities of the resulted materials were characterized by temperature-programmed desorption of NH3. The direct synthesis of dimethyl ether (DME) from syngas was carried out over the admixed catalysts of an industrial CuO–ZnO–Al2O3 methanol synthesis catalyst and the parent and antimony oxide modified HZSM-5 zeolites under pressurized fixed-bed continuous flow conditions. The results indicated that modification of HZSM-5 with suitable amount of antimony oxide significantly decreased the selectivity for undesired byproducts like hydrocarbons and carbon dioxide from 9.3% and 32.4% to less than 1% and 28%, respectively, so the selectivity for DME was enhanced greatly from 55% to 69% under temperature of 260°C, pressure of 4MPa and gas hourly space velocity of 1500mLh−1 . The decrease in the formation of hydrocarbons and carbon dioxide can be attributed to the significant decline in the amount of strong acid sites of the HZSM-5 zeolite induced by antimony oxide modification. Additionally, the influences of the operating parameters on the performance of the most efficient catalyst were also investigated. The results showed that high reaction temperature and high gas hourly space velocity resulted in both lower carbon monoxide conversion and lower dimethyl ether selectivity, so they should be no higher than 280°C and 3000mLh−1 , respectively. [Copyright &y& Elsevier]

Abstract: A series of γ-Al2O3 samples modified with various contents of sulfate (0–15wt.%) and calcined at different temperatures (350–750°C) were prepared by an impregnation method and physically admixed with CuO–ZnO–Al2O3 methanol synthesis catalyst to form hybrid catalysts. The direct synthesis of dimethyl ether (DME) from syngas was carried out over the prepared hybrid catalysts under pressurized fixed-bed continuous flow conditions. The results revealed that the catalytic activity of SO4 2−/γ-Al2O3 for methanol dehydration increased significantly when the content of sulfate increased to 10wt.%, resulting in the increase in both DME selectivity and CO conversion. However, when the content of sulfate of SO4 2−/γ-Al2O3 was further increased to 15wt.%, the activity for methanol dehydration was increased, and the selectivity for DME decreased slightly as reflected in the increased formation of byproducts like hydrocarbons and CO2. On the other hand, when the calcination temperature of SO4 2−/γ-Al2O3 increased from 350°C to 550°C, both the CO conversion and the DME selectivity increased gradually, accompanied with the decreased formation of CO2. Nevertheless, a further increase in calcination temperature to 750°C remarkably decreased the catalytic activity of SO4 2−/γ-Al2O3 for methanol dehydration, resulting in the significant decline in both DME selectivity and CO conversion. The hybrid catalyst containing the SO4 2−/γ-Al2O3 with 10wt.% sulfate and calcined at 550°C exhibited the highest selectivity and yield for the synthesis of DME. [Copyright &y& Elsevier]

Abstract: The deactivation and regeneration of B2O3/TiO2-ZrO2 catalyst for the vapor phase Beckmann rearrangement of cyclohexanone oxime to ɛ-caprolactam were studied. The fresh, deactivated and regenerated catalysts were characterized by using adsorption of nitrogen, X-ray diffraction (XRD), thermogravimetry (TG) and NH3-temperature-programmed desorption (NH3-TPD) techniques. The crystal structure and pore size distribution of the catalyst were retained after reaction, but the number of acid sites decreased significantly. There was a relationship between the amount of coke deposited on the catalyst and the decline in catalytic activity. These results suggest that the coke deposition on the surface of catalyst is mainly responsible for the catalyst deactivation. The catalytic activity can be recovered completely after calcining the deactivated catalyst in air flow at 600°C for 8h. [Copyright &y& Elsevier]

Abstract: A series of HZSM-5 zeolites modified with various contents of magnesium oxide (0–10 wt%) were prepared with an incipient impregnation technique and characterized by X-ray diffraction, N2 adsorption, temperature-programmed desorption of NH3 and CO2, 27Al MAS NMR, and FT-IR. The modified HZSM-5 zeolites were mixed physically with methanol synthesis components (CuO–ZnO–Al2O3) to perform the direct synthesis of dimethyl ether (DME) from syngas under pressurized fixed-bed continuous-flow conditions. The results indicated that modification of HZSM-5 with a suitable amount of MgO significantly decreased the selectivities for undesired by-products like hydrocarbons and CO2 from 9.3 and 37.1% to less than 0.4 and 31%, respectively, through the removal of unselective strong Brønsted acid sites and hence enhanced the selectivity for DME from 49% to more than 64%, whereas the conversion of carbon monoxide was scarcely affected. However, when the MgO contents were equal to or higher than 5 wt%, both the conversion of CO and selectivity for DME decreased markedly because of the decreased activity for methanol dehydration. A mechanism for methanol dehydration to DME involving both acidic and basic sites on the HZSM-5 zeolites modified with MgO has been proposed based on the results obtained. [Copyright &y& Elsevier]

[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 hybrid systems of CuO-ZnO-Al 2 O 3 /HZSM-5 for the one-step synthesis of DME from biomass-derived syngas were prepared by four different combination methods (granule-mixing, powder-mixing, physical coating and dual-bed fixing) and characterized by N 2 adsorption, XRD, N 2 O titration, H 2 -TPR, NH 3 -TPD and TG techniques. The influences of combination method on the physicochemical properties and catalytic performances of hybrid catalyst were investigated, and the relationship among the combination method, the synergistic effect and the WGS reaction was discussed based on the composition features of the biomass-derived syngas (CO 2 -rich and H 2 -deficient). A maximum of CO conversion and DME yield was obtained over the hybrid catalyst prepared by granule-mixing method. There is a synergistic effect, which remarkably promotes the formation of DME, between the methanol synthesis and the methanol dehydration over the hybrid catalysts except for the hybrid system configured using the dual-bed fixing method. The WGS reaction, playing a pivotal role in the direct DME synthesis because of the in-situ produced hydrogen, relates to the combination method closely. An interaction between the two catalyst components arising in the combination process affects the properties of active sites and further the catalytic performances. The deactivation of the hybrid catalyst is ascribed mainly to the increase in the particle size of Cu in CuO-ZnO-Al 2 O 3. [Display omitted] • Combination method affects synergistic effect, WGS reaction and catalytic property. • Synergistic effect was observed in direct DME synthesis from biomass-derived syngas. • Hydrogen produced via WGS reaction plays an important role for direct DME synthesis. • Interaction between CZA and HZSM-5 changes the amount and property of active site. • Deactivation of hybrid catalyst is ascribed to the increase in d Cu in CZA component. [ABSTRACT FROM AUTHOR]

In this study, a series of Cu–Ce 1-x Zr x O 2 (x = 0, 0.2, 0.5, 0.8, 1) catalysts were prepared by an eco-friendly and facile solid-phase grinding method. The effect of different Ce/Zr molar ratios on the performance of Cu–Ce 1-x Zr x O 2 catalysts for CO 2 hydrogenation to methanol was investigated. The results showed that the Cu–Ce 0.5 Zr 0·5 O 2 catalyst had the best catalytic performance, with CO 2 conversion of 15.2 % and methanol yield of 7.5 % at GHSV = 3600 mL/(g cat ·h)); when GHSV was increased to 20,000 mL/(g cat ·h), the space-time yield of methanol reached 270.8 g CH3OH /(kg cat ·h). X-ray diffraction (XRD), scanning electron microscope (SEM), N 2 adsorption-desorption, N 2 O chemisorption, X-ray photoelectron spectroscopy (XPS), temperature-programmed reduction by H 2 (H 2 -TPR), and temperature programmed desorption (H 2 -TPD, CO 2 -TPD) techniques were used to characterize the catalysts, and the higher reactivity of Cu–Ce 0.5 Zr 0·5 O 2 can be attributed to more Cu0 species, defect oxygen and basic sites. In situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTs) results revealed that the hydrogenation of CO 2 to methanol occurred through the formate intermediate pathway. This work proposed an eco-friendly and facile method for the preparation of high-performance Cu-based catalysts and the systematic study provided a deep insight for the development of high-performance Cu-based catalysts for methanol synthesis from CO 2 hydrogenation. [ABSTRACT FROM AUTHOR]

• Activity, selectivity and H 2 O resistance of Mn–Ce/TiO 2 catalyst was improved by Co. • Operation temperature window of Mn–Ce/TiO 2 catalyst was broadened by Co. • The Co–Mn–Ce/TiO 2 with Co/Ti molar ratio of 0.4 exhibits the best performance. • NH 3 -SCR reaction of the (Co)Mn–Ce/TiO 2 catalysts follows L-H and E-R mechanisms. • Detailed structure-performance relationships of investigated catalysts are obtained. The promotional effect of cobalt (Co) modification on MnCeO x /TiO 2 catalyst for selective catalytic reduction of NO with NH 3 (NH 3 -SCR) was investigated extensively in this study. A series of CoMnCeO x /TiO 2 catalysts with different Co contents were prepared by the facile impregnation method and characterized by XRD, N 2 sorption, XPS, H 2 -TPR, NH 3 /NO-TPD, and in situ DRIFT spectroscopy. The results indicate that the modification of MnCeO x /TiO 2 by Co could significantly improve its low-temperature activity and N 2 selectivity, and broaden operation temperature window (>95% NO conversion at 100–225 °C), and that the optimal mole ratio of Co to Ti in the catalyst is 0.4. Furthermore, the introduction of Co to MnCeO x /TiO 2 could obviously enhance H 2 O resistance. The characterization results reveal that the addition of Co to the MnCeO x /TiO 2 catalyst could enhance the dispersion of MnO x and CeO x , and increase the relative ratio of Mn4+ and Ce3+ on the catalyst surface. In addition, the surface area of MnCeO x /TiO 2 is enlarged evidently after doping of Co. From the results of H 2 -TPR, NH 3 /NO-TPD, and NO oxidation, CoMnCeO x /TiO 2 exhibits stronger reducibility, larger adsorption capacity for NH 3 and NO, and higher NO to NO 2 conversion than MnCeO x /TiO 2 , thus obtaining the higher SCR activity, N 2 selectivity, and H 2 O tolerance. In situ DRIFT spectroscopy tests indicate that the NH 3 -SCR reaction on both MnCeO x /TiO 2 and CoMnCeO x /TiO 2 follow simultaneously the Langmuir-Hinshelwood and Eley-Rideal mechanisms. [ABSTRACT FROM AUTHOR]

• Regenerable DAC process using lysine as a sorbent and N-doped 3D graphene as a catalyst. • N-doped 3D graphene using as an absorption/desorption-enhanced bifunctional catalyst. • The chemical mechanism of DAC was postulated and confirmed by FTIR and DFT. Direct air capture (DAC) of CO 2 is vital for combating global climate change, but DAC technologies have a low absorption efficiency due to the low concentration (∼400 ppm) of atmospheric CO 2. A novel DAC technology was developed to solve this issue using lysine (an amino acid) as a sorbent and N-doped 3D graphene as an absorption/desorption-enhanced bifunctional catalyst. Introducing only 500 ppm N-3DG catalyst increased the working time (≥90% CO 2 absorption efficiency) by 233% and its absorption capacity by 197%. The catalyst also significantly accelerated the CO 2 working desorption capacity and rate by ∼280% and ∼338% at 70 °C, enabling regeneration of the sorbent by utilizing low-temperature waste heats. Furthermore, the excellent stability of the system was confirmed by 50 cyclic tests. The chemical mechanism driving catalytic CO 2 capture was postulated and confirmed by density functional theory computations. This study provides a new strategy for developing next-generation DAC technologies. [ABSTRACT FROM AUTHOR]

[Display omitted] • An approach to strengthen the boundary role of Pd/CeO 2 catalyst was developed. • Interfacial catalytic activity was investigated by B-TOF and I 0 × B-TOF. • The CO catalytic oxidation mechanism was proposed on the basis of boundary catalysis. Recently, the interface catalysis has caused more and more attentions. Herein, we developed an approach to strengthen the boundary role of Pd/CeO 2 catalyst, resulting in an obvious increase in its catalytic performance for CO oxidatio n with 100% CO conversion at 20 °C. The results show that after the pretreatment in N 2 at 750 °C and reduction in H 2 at 300 °C, the interaction between Pd and CeO 2 was enhanced, and smaller Pd0 particles and longer interface length (I 0) of Pd-CeO 2 were obtained. In the boundary of Pd-CeO 2 , the presence of Pd2+ promotes the formation of oxygen vacancies in CeO 2 , and CO adsorbed on Pd0 reacts with the oxygen species activated by the oxygen vacancy. The Pd0 sites and oxygen vacancies in the boundary play a decisive role in the CO oxidation over Pd/CeO 2 , which is proved by the B-TOF and I 0 × B-TOF. [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]