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Partial hydrogenation of benzene to cyclohexene is attractive in terms of feedstock accessibility, atomic economy, and operational simplicity. Herein, a series of Ru/ZrO2 catalysts were prepared by post-treatment of a binary Ru-Zn/ZrO2 catalyst using 5-30 wt % NaOH aqueous solutions. Alloying between Ru and Zn was evidenced for the catalyst post-treated only by water (Ru/ZrO2-0). Alkaline post-treatment removed metallic Zn, forming smaller Ru nanoparticles. Concomitantly, the hydrophilicity of the catalysts was increased and maximized on the 10 wt % NaOH-treated catalyst (Ru/ZrO2-10). In partial hydrogenation of benzene, the Ru/ZrO2-0 catalyst displayed the highest turnover frequency but the lowest initial selectivity to cyclohexene, whereas the Ru/ZrO2-10 catalyst exhibited the highest initial selectivity (86 %) and yield of cyclohexene (51 %) among the catalysts investigated. A quantitative relationship between the initial selectivity to cyclohexene and the hydrophilicity of these catalysts was identified, which rationalizes the significant impact of alkaline post-treatment on selectivity enhancement in partial hydrogenation of benzene to cyclohexene over Ru/ZrO2 catalysts. [ABSTRACT FROM AUTHOR]

The textural and structural properties of a skeletal Ni catalyst prepared by alkali leaching of aluminum from the rapidly quenched Ni50Al50 alloy have been investigated by elemental analysis (ICP-AES), nitrogen physisorption, powder X-ray diffraction (XRD), scanning electron microscopy (SEM), and H2 thermal desorption techniques. As compared to Raney Ni, such a skeletal catalyst has a residual Ni2Al3 phase, lower surface area, higher average pore diameter and porosity, larger mean crystallite size, and unit-cell parameter. These differences are attributable to the metastable character of the pristine rapidly quenched alloy and their relationship with the catalytic behavior is discussed and correlated. [Copyright &y& Elsevier]

Abstract: Effect of promoters (Co, Fe, Sn, Zn) on structures, properties and catalytic performance of RuB/γ-Al2O3 catalyst was studied using in situ XRD, TEM, H2-TPD, XPS and liquid-phase hydrogenation of ethyl lactate to 1,2-propanediol (PDO). It was found that incorporation of Sn or Fe improved the dispersion and thermal stability of RuB. The electron density of Ru and the strength and capacity of H2 adsorption on the RuB catalyst were also enhanced by the incorporation of Sn or Fe. The incorporation of Co or Zn led to a significant decrease in H2 adsorption capacity of the RuB catalyst. Both ethyl lactate conversion and selectivity to 1,2-PDO increased with the incorporation of Sn or Fe. The ethyl lactate conversion decreased sharply with the incorporation of Zn or Co accompanied by an increase in selectivity to 1,2-PDO and lactic acid. The effect of promoters on reaction behavior was discussed on the basis of the characterizations. [Copyright &y& Elsevier]

Amorphous Ru-B supported on γ-Al2O3 was prepared by a novel reductant impregnation method for the hydrogenation of ethyl lactate to 1,2-propanediol (PDO). The effects of tin on composition, physicochemical properties, thermal stability and reaction behavior of Ru-B/γ-Al2O3 catalyst were studied by using in situ XRD, TEM, H2-TPD, XPS and liquid phase hydrogenation of ethyl lactate. The Ru-B/γ-Al2O3 catalyst prepared by reductant impregnation showed good activity for hydrogenation of ethyl lactate. Addition of suitable amounts of tin (Sn/Ru atomic ratio of 7%) significantly increased the ethyl lactate conversion and the selectivity to 1,2-PDO; a selectivity to 1,2-PDO of 91.5% was obtained at ethyl lactate conversion of 90.7% under mild reaction conditions. The characterizations showed that addition of tin improved the dispersion and thermal stability of Ru-B significantly. The B/Ru ratio of the catalyst, the electron density of Ru, and the strength of hydrogen adsorption of the catalyst increased with increase of tin content over the range studied. [Copyright &y& Elsevier]

Development of a water-gas shift (WGS) catalyst durable in dynamic shutdown/startup operation is essential to enable residential applications of H2-powered fuel-cell systems but remains a conundrum for heterogeneous catalysis. We demonstrate herein that by isomorphic substitution of Zr in the lattice of CeO2 to increase the acid density of the catalyst, complemented by dosing a small amount of O2 to realistic reformate to improve the oxidizing potential, the formation of the notorious site-blocking carbonate species on the Au catalyst can be efficiently retarded. This allows the formation of a highly robust Au/Ce0.4Zr0.6O2 WGS catalyst suitable for the challenging shutdown/startup operation in realistic reformate. [ABSTRACT FROM AUTHOR]

Highlights: [•] B-doped ZrO2 (B-ZrO2) with various acid amounts (n NH3) from NH3-TPD were prepared. [•] The Ru/B-ZrO2 catalysts were evaluated in benzene hydrogenation to cyclohexene. [•] The turnover frequency of benzene was linearly proportional to n NH3. [•] B doping enabled a maximum initial selectivity (S 0) of 88% toward cyclohexene. [•] A volcanic evolution trend between S 0 and n NH3 was unveiled. [ABSTRACT FROM AUTHOR]

Abstract: The deactivation mechanisms of the Au/CeO2 catalyst in steady-state and shutdown/start-up WGS reactions were investigated in realistic reformate at 250°C. Catalyst deactivation due to sintering was excluded. After steady-state operation, the original activity was not recovered by removing the deposited carbonate species. The influences of the component gases of realistic reformate on the activity suggest that loss of the Au–CeO2 interaction caused by the reducing H2 and CO is the main reason for catalyst deactivation. Under the shutdown/start-up condition, the catalyst suffered more drastic deactivation, although it underwent a lesser degree of reduction. A good correlation between the extent of deactivation and the amount of the carbonate species indicates that catalyst deactivation is mainly caused by enhanced formation of the carbonate species, especially through a combined effect of CO2 and H2O, during the low-temperature shutdown and start-up steps. The implications of these findings for improved applications of the Au/CeO2 catalyst in WGS are indicated. [Copyright &y& Elsevier]

Abstract: Cu/ZnO catalysts with Cu loadings of 44–5 wt% were prepared by coprecipitation and evaluated in temperature-dependant and shut-down/start-up water–gas shift (WGS) reactions using realistic reformate. These catalysts had similar Cu crystallite sizes, and the metallic Cu surface area and surface Cu content increased with the Cu loading. In temperature-dependent reactions, the CO conversion on the 25wt%Cu/ZnO catalyst slightly exceeded that on 44wt%Cu/ZnO. In shut-down/start-up operation, which is imperative for mobile and residential fuel cell applications, the catalysts with Cu loadings higher than 5 wt% suffered slight activity loss. Among them, the 15wt%Cu/ZnO catalyst deactivated the most reluctantly. As a result, after three shut-down/start-up cycles the CO conversion on 15wt%Cu/ZnO, 25wt%Cu/ZnO, and 44wt%Cu/ZnO became comparable. These results demonstrate the feasibility to lower the Cu loading without degrading the WGS performance of the Cu/ZnO catalyst in shut-down/start-up operation, which will guarantee the operation safety when the catalyst will be operated unattended for domestic small-scale fuel cell applications. Unexpectedly, the CO conversion was doubled on 5wt%Cu/ZnO after one shut-down/start-up cycle, which is interpreted as the redispersion of Cu nanoparticles based on transmission electron microscopy (TEM) and temperature-programmed reduction (TPR). [Copyright &y& Elsevier]

Abstract: Au/Fe3O4 catalysts with flowerlike and particulate morphologies have been prepared by homogeneous deposition–precipitation of gold on hematite materials synthesized in different ways, followed by integrative reduction. HRTEM revealed the heteroepitaxial growth of gold crystallites on flowerlike magnetite materials along the {111} planes, which may account for their smaller and more uniform gold nanoparticles. The stronger metal-support interaction on flowerlike Au/Fe3O4 catalysts was also manifested by the higher reduction temperature of gold than that on particulate magnetite-supported catalysts. In liquid phase hydrogenation of crotonaldehyde, the flowerlike Au/Fe3O4 catalysts show high selectivity (⩾76%) in the entire reaction course and high yield (⩾75%) to crotyl alcohol. They also display excellent separation and recycling characteristics. A perimeter interface mechanism involving the hydroxyl groups on magnetite and the positively charged gold atoms linked to the lattice oxygen of magnetite is established to address the remarkably high selectivity over the flowerlike Au/Fe3O4 catalysts. [Copyright &y& Elsevier]

Abstract: Co/ZnO catalysts with different Co/Zn ratios have been prepared by the coprecipitation method. It is revealed that below the nominal Co/Zn molar ratio of 2, the calcined Co/ZnO samples were constituted by ZnO and ZnCo2O4 spinel. At the nominal Co/Zn ratio of 2, a small amount of Co3O4 spinel emerged. After reduction, the catalysts were composed of fcc Co and ZnO. In aqueous-phase reforming (APR) of ethylene glycol, it is found that the intrinsic activity and selectivity to H2 increase with the increment of the ZnO content. H2 selectivities over the Co/ZnO catalysts ranged from 52% to 89%, which are substantially higher than that of the Raney Ni catalyst at similar conversion. Moreover, the Co/ZnO catalysts produced much less CO in the product gas. With the aid of literature works as well as additional experiments on APR of acetic acid, methanol, and ethanol, the reaction pathways of ethylene glycol in the presence of water on the Co/ZnO catalysts were discussed. [ABSTRACT FROM AUTHOR]

Abstract: A high-performance Pd/Fe3O4 catalyst for aqueous-phase reforming (APR) of ethylene glycol (EG) to H2 was prepared facilely by the co-precipitation method. After proper activation, the Pd was present as highly dispersed metallic nanoparticles with dimension of <3nm, and the Fe was present as magnetite. When compared to Pd catalyst supported on Fe2O3, NiO, Cr2O3, Al2O3, or ZrO2 prepared by incipient wetness impregnation, the Pd/Fe3O4 catalyst displayed superior catalytic performance in terms of activity, selectivity, and stability. The intrinsic activity of the Pd/Fe3O4 catalyst was about three times of that of the second most active Pd/Fe2O3 catalyst under the same reaction conditions. In addition, the Pd/Fe3O4 catalyst retained ∼80% of its initial activity after reaching the steady-state. Notably, the Pd/Fe3O4 catalyst possessed the highest turnover frequency of H2 (109min−1) reported so far, showing its promise as a new practical catalyst for APR of biomass-derived oxygenates to H2. The excellent catalytic performance of the Pd/Fe3O4 catalyst was attributed to the enhanced synergistic effect between small Pd nanoparticles and magnetite in promoting the water–gas shift reaction, the rate-determining step in APR of EG over Pd-based catalysts. [Copyright &y& Elsevier]

Abstract: A rapidly quenched skeletal Ni (RQ Ni) prepared by the melt-spinning method followed by alkali leaching was used as a new category of Ni precursor to fabricate effective chiral Ni catalyst. A series of tartaric acid (TA)–NaBr–modified RQ Ni catalysts (MRQNi) were derived, and the textural and structural properties of the MRQNi catalysts were systematically investigated. It is found that the modification conditions influence profoundly the composition, texture, and Ni crystallite size of the MRQNi catalysts. In liquid phase hydrogenation of butanone to R-(−)-2-butanol, the optimized MRQNi catalyst exhibits much better activity and enantioselectivity than the similarly chirally modified Raney Ni catalyst. Based on the characterizations, the superior catalytic performance of the MRQNi catalyst is mainly attributed to the higher surface content of the sodium–nickel(II) tartrate complex than that on the chirally modified Raney Ni catalyst. [Copyright &y& Elsevier]

Abstract: The Cu/ZnO/Al2O3 catalysts were prepared by the coprecipitation method, and were evaluated in the water–gas shift (WGS) reaction. The effects of the calcination temperature on the BET surface area and crystallite size were characterized. In WGS reaction, the Cu/ZnO/Al2O3 catalysts suffered from continuous deactivation in shut-down/start-up operation – the daily requirement for mobile and residential fuel cell systems. Among them, the Cu/ZnO/Al2O3 catalyst prepared at the calcination temperature of 450°C showed the best activity and stability, with the decrement of the CO conversion of only 12.8% after three shut-down/start-up cycles. Deactivation of the Cu/ZnO/Al2O3 catalysts is attributed to the blocking or deterioration of the active sites by Zn6Al2(OH)16CO3·4H2O resulting from the degeneration of the oxides under cyclic operations. Removal of the hydroxycarbonate species by calcination in air followed by re-reduction could restore the steady-state WGS activity; however, the regenerated catalyst underwent much severe deactivation in subsequent shut-down/start-up operation. [Copyright &y& Elsevier]

Uniform Co–B nanoparticles were synthesized for the first time by chemical reduction of cobalt ion with borohydride in an oil-in-water microemulsion system comprising cyclohexane, polyethylene glycol, and water. The particle size was controlled by modulating the cyclohexane content. With the characterization of X-ray diffraction, selective area electronic diffraction, X-ray photoelectron spectroscopy, and transmission electron microscopy, the resulting Co–B nanoparticles were identified to be amorphous alloys ranging in size from 6 to 20 nm. During liquid-phase cinnamaldehyde hydrogenation, the as-synthesized Co–B catalyst was extremely active and more selective than the regular Co–B prepared in aqueous solution. Furthermore, this catalyst also was found to be more durable during the hydrogenation process. [Copyright &y& Elsevier]

Abstract: Uniform spherical Co-B amorphous alloy nanoparticles were prepared by ultrasound-assisted reduction of Co(NH3)2+ 6 with BH− 4 in aqueous solution, and the particle size was adjusted by changing either the ultrasound power or the ultrasonication time. During liquid-phase cinnamaldehyde (CMA) hydrogenation, the as-prepared Co-B catalyst exhibited much higher activity and better selectivity to cinnamyl alcohol (CMO) than the regular Co-B obtained by direct reduction of Co2+ with BH− 4. The higher activity can be attributed to both the higher dispersion of Co active sites () and the higher intrinsic activity (). The higher selectivity can be attributed to both the uniform Co-B amorphous alloy particles and the strong electronic interaction between Co and B, which enhances the competitive adsorption of Cgainst Cn the CMA molecule. Meanwhile, the stronger adsorption for hydrogen on Co active sites was more favorable for Cnation in comparison with the Cnation. [Copyright &y& Elsevier]

Abstract: Skeletal Ni (RQ Ni) catalyst was prepared by alkali leaching of rapidly quenched Ni50Al50 alloy. By impregnating RQ Ni with SnCl4 followed by thermal treatment in inert atmosphere, homogeneous Sn-modified skeletal Ni (RQ Ni–Sn) catalysts were obtained. It was found that thermal treatment induces alloying of the deposited metallic Sn with Ni, forming Ni3Sn alloy segregated on the catalyst surface. In aqueous-phase reforming of ethylene glycol, the RQ Ni catalyst was less selective in producing H2 but more selective in producing alkanes than the Raney Ni catalyst described in the literature. This is attributed to the expansion of the lattice of RQ Ni favoring the dissociation of CO and, consequently, the methanation reaction consuming H2. Moreover, the structural difference influences the reaction pathway, with the undesired Ce pathway obstructed on RQ Ni. Modification of RQ Ni with Sn drastically improves the H2 selectivity. On the RQ Ni80Sn20 catalyst, alkane production was virtually retarded, whereas H2 selectivity as high as 98 mol% was achieved at high conversion. Based on the characterizations and previous findings, it is suggested that Sn may block the active sites for CO adsorption and/or dissociation, thus suppressing the undesired methanation reaction. On the other hand, bifunctional Ni–Sn ensembles may form, in which Sn facilitates H2O dissociation while neighboring Ni adsorbs CO, thus promoting the desired water–gas shift reaction, leading to more H2. [Copyright &y& Elsevier]

Abstract: Skeletal Ni catalysts (RQ Ni) prepared by alkali leaching of rapidly quenched Ni–Al alloys have been systematically characterized, focusing on the effect of the cooling rate during alloy preparation. It is found that the residual Al content, texture, structure, surface hydrogen species, and active sites of the RQ Ni catalysts can be controlled by the cooling rate of the Ni–Al alloys. In liquid-phase hydrogenation of 2-ethylanthraquinone (eAQ), the RQ Ni catalyst with higher cooling rate favors hydrogenation of the carbonyl group and retards the saturation of the aromatic ring and the formation of the degradation products, thus leading to a higher yield of H2O2. Based on the characterizations, the improved selectivity is ascribed to the dominant population of strongly chemisorbed hydrogen, which is inactive for the hydrogenation of the aromatic ring, along with the electronic interaction between residual metallic Al and Ni, favoring a carbonyl group-bonded configuration of eAQ on the catalyst. [Copyright &y& Elsevier]

Abstract: Liquid-phase hydrogenation of 2-ethylanthraquinone to 2-ethylanthrahydroquinone has been investigated over Raney Ni, nanosized amorphous Ni–B, and chromium-modified Ni–B catalysts. It has been found that the amorphous Ni–B and chromium-modified Ni–B catalysts exhibited superior selectivity, whereas the chromium-modified Ni–B catalysts had better activity and selectivity than unmodified Ni–B catalyst. Based on the characterizations, the higher selectivity of the amorphous catalysts is ascribed to the dominant population of the strongly bound hydrogen, which is not reactive for the hydrogenation of the aromatic ring, along with the repulsive interaction between the aromatic ring and the electron-rich Ni due to electron donation from alloying B. The addition of chromium decreased the particle size of the amorphous catalysts, which is beneficial for the improvement of activity. Moreover, surface chromium oxide can function as a Lewis acid, which lowers the orbital of the reactant, favoring a carbonyl group-bonded configuration. The best selectivity was achieved over the Ni–Cr–B2 catalyst, where the hydrogenation of the aromatic ring was thoroughly blocked before the saturation of the carbonyl groups. [Copyright &y& Elsevier]

A colloidal RuB/Al2O3·xH2O catalyst has been synthesized through a combined coprecipitation–crystallization–reduction strategy and characterized in detail with techniques including ICP-AES, N2 physisorption, XRD, TG/DTA, PSD and TEM. The catalytic behavior in liquid phase selective hydrogenation of benzene to cyclohexene was studied and compared with that of the RuB/γ-Al2O3 catalyst prepared by the incipient-wetness impregnation method. The RuB/Al2O3·xH2O catalyst is found more reactive than the RuB/γ-Al2O3 catalyst, and the maximum yield of cyclohexene is about four times as high as that over the latter. The better activity of the colloidal catalyst is assigned to the higher dispersion of the smaller RuB particles, whereas its superior selectivity is attributed to the improved hydrophilicity due to higher content of structural water and surface hydroxyl groups. [Copyright &y& Elsevier]

The ultrafine Ni–Co–B amorphous alloys with Co/(Co + Ni) molar ratio (χCo) varying from 0 to 1 was prepared by chemical reduction of mixed Ni2+ and Co2+ ions with BH4- in aqueous solution. During liquid phase acetonitrile hydrogenation to ethylamine, the specific activity (Rm) and the intrinsic activity (TON) of the Ni–Co–B catalyst first increased and then decreased with the increase of χCo from 0 to 1. The maximum activity was obtained at χCo = 0.5; the value of the activity was nearly twice as that of the Ni–B or the Co–B catalyst. Treatment of the Ni–Co–B catalyst at 873K resulted in an abrupt decrease in the activity due both to a decrease in active surface area and, especially, to the crystallization and the decomposition of the Ni–Co–B amorphous alloy. The selectivity to ethylamine increased rapidly with χCo and then remained constant at χCo ≥ 0.5. The maximum yield of ethylamine could reach 93%, showing a good potential for industrial applications. According to kinetic studies and results of various characterization methods, such as ICP, XRD, EXAFS, XPS, SAED, TEM, DSC, TPD, and hydrogen chemisorption, the correlation of the catalytic performance to both the structural and the electronic characteristics was discussed briefly. The activation of the CN and/or CN bonds, the promotion on the hydrogen adsorption, and the inhibition on the ethylamine adsorption were the decisive factors responsible for the excellent activity and selectivity of the Ni–Co–B catalyst. [Copyright &y& Elsevier]

The effects of pore structure on the reaction rates and selectivities in the liquid-phase hydrogenation of 2-ethylanthraquinone over NiB amorphous alloy catalysts prepared by the reductant-impregnation method were studied using regular (HMS, MCM-41, and SBA-15) and commercial mesoporous silicas as supports. The composition, particle size, and location of the NiB particles were profoundly influenced by the pore structure of the supports. It is found that the location of the NiB particles depended on the pore size of the supports, whereas the uniformity of particle size was related to the interaction between the NiB particles and the supports. The hydrogenation rate was much faster on NiB catalysts with pore diameters exceeding 5 nm than on the narrow-pore catalysts, whereas the selectivity to 2-ethyldihydroanthraquinone, the carbonyl group hydrogenation product, was higher on NiB catalysts supported on regular mesoporous silicas. The best activity and selectivity were achieved when using SBA-15 as the support, which is attributable to the formation of more uniform active sites due to the unique pore structure of SBA-15. [Copyright &y& Elsevier]

A Ru–Zn/m-ZrO2 nanocomposite catalyst for benzene partial hydrogenation to cyclohexene was prepared by coprecipitation of ruthenium trichloride and zirconium oxychloride with ammonia, followed by hydrogen reduction in an aqueous zinc sulfate solution. By use of transmission electron microscopy (TEM), powder X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS), the reduction of zinc cation to metallic zinc and the transformation of zirconium hydroxide to monoclinic zirconia were proposed and explained. The hydrogenation parameters, such as the amount of zinc sulfate in the pretreatment process, the hydrogenation temperature, the stirring rate, and the hydrogen pressure, influenced the yield of cyclohexene. The pronounced positive effect of metallic zinc in enhancing the cyclohexene yield was discussed. [Copyright &y& Elsevier]

The Ni-B and Co-B amorphous alloys exhibited much higher activity and selectivity to ethylamine (C2H5NH2) than their corresponding crystallized counterparts and Raney Ni during liquid phase hydrogenation of acetonitrile (CH3CN). In comparison with the Ni-B amorphous alloy, the Co-B amorphous alloy exhibited longer lifetime and better selectivity, though its activity was slightly lower. The maximum yield of C2H5NH2 could reach 93.5%, showing a good potential in industrial application. The higher activity of the amorphous alloys could be attributed to the large active surface area, the unique amorphous structure together with the suitable structural parameters, and the electron donation of the alloying B to the metallic Ni or Co. The resulted electron-enriched metallic active sites may also account for the better selectivity to C2H5NH2 of the amorphous alloys since, on one hand, it could promote the hydrogenation of CH3CH&z.dbnd6;NH toward C2H5NH2 by activating the C&z.dbnd6;N bond; and on the other hand, it may retard the condensation between CH3CH&z.dbnd6;NH and C2H5NH2 leading to (C2H5)2NH by inhibiting the adsorption of C2H5NH2 which was essential for the condensation. The Co-B amorphous alloy was more selective than the Ni-B owing to its stronger adsorption for CH3CN and the higher electron density on the Co active sites, both of them could inhibit the adsorption for C2H5NH2 and in turn, retard the condensation. This could also account for its longer lifetime. However, such stronger adsorption for CH3CN was harmful for the competitive adsorption for hydrogen and in turn resulted in a slightly lower hydrogenation activity than the Ni-B since the CH3CN hydrogenation was first-order with respect to hydrogen while zero-order to CH3CN. [Copyright &y& Elsevier]

The La-doped Co-B/SiO2 amorphous catalyst (Co-La-B/SiO2) was prepared by chemical reduction of mixed Co2+ and La3+ ions deposited on a silica support with KBH4 aqueous solution at room temperature. The catalyst was employed in the liquid phase hydrogenation of cinnamaldehyde (CMA) to cinnamyl alcohol (CMO). At suitable content, the La-additives exhibited promoting effects on both the activity and the selectivity to CMO. The optimum La-content (χLa) was determined as 0.014 (molar fraction), over which the CMO yield could reach 80%. Based on various characterizations, the promoting effect of the La-dopant on the selectivity to CMO was mainly attributed to the presence of La2+ and La3+. These La-species were favorable for both the activation of the C&z.dbnd6;O bond and the formation of H− species and thus, promoted the hydrogenation of C&z.dbnd6;O bond. These roles also promoted the hydrogenation activity. Besides, the promoting effect of the La-dopant might also attributed to the presence of the La oxides which increased the surface Co active sites. At high χLa, the activity decreased again due to the coverage of the Co active sites by the inactive La-additives and also due to the too strong adsorption of carbonyl group induced by La3+ and La2+. Such strong adsorption might hinder the competitive adsorption of hydrogen. [Copyright &y& Elsevier]

A Ru-B amorphous alloy catalyst in the form of ultrafine particles was prepared by chemical reduction of RuCl3 with borohydride in aqueous solution, whose amorphous structure was confirmed by XRD, DSC, and SAED. Heating pretreatment resulted in the rapid crystallization and the deep decomposition of the Ru-B amorphous alloy as well as the abrupt decrease in the surface area due to the gathering of small particles at high temperature. XPS spectra revealed that partial electrons transferred from the alloying B to the metallic Ru in the as-prepared Ru-B sample. In comparison with other catalysts, the as-prepared Ru-B amorphous catalyst exhibited excellent activity and perfect selectivity to d-glucitol as well as superior lifetime during the liquid phase glucose hydrogenation, showing its potential application in industrial process. The higher activity of the Ru-based catalysts than that of other metal catalysts, such as Co-B and Ni-B amorphous catalysts as well as Raney Ni catalysts, demonstrated that the metallic Ru was more active than both metallic Ni and Co for the glucose hydrogenation. Meanwhile, the Ru-B amorphous catalyst exhibited higher activity than its corresponding crystallized Ru-B and pure Ru powder catalysts, showing the promoting effects of both the amorphous structure and the electronic interaction between the metallic Ru and the alloying B, which was briefly discussed based on the kinetic studies and various characterizations. [Copyright &y& Elsevier]

Some ultrafine Ni-B amorphous alloys with variable B contents were prepared by chemical reduction under different conditions. The effect of the B content on their activities was evaluated by using the liquid phase cyclohexene hydrogenation as a probe. Both the specific activity and the TOF value increased with the increase of the B content, showing the promoting effect of the alloying B on the hydrogenation activity, which was mainly attributed to its modification of the nature of the Ni active sites. Concerning the structural effect, the XRD patterns revealed that the amorphous degree of the as-prepared Ni-B alloy increased with the increase of the B content. Meanwhile, the DSC analysis demonstrated that increase of the B content could increase the thermal stability of the Ni-B amorphous alloy and in turn, delay its crystallization during the cyclohexene hydrogenation. Furthermore, the EXAFS also demonstrated that the Ni active sites became more highly unsaturated at higher B content. These structural modifications were favorable for the hydrogenation activity. Concerning the electronic effect, the XPS spectra demonstrated the electronic interaction between Ni and B in the Ni-B amorphous alloy, making Ni electron-enriched while B became electron-deficient. According to the DFT calculations, more electrons may transfer from the alloying B to Ni with the increase of the B content. Such electronic modifications may also facilitate the cyclohexene hydrogenation. [Copyright &y& Elsevier]

[Display omitted] • The Pt/W-MCFs catalysts with different cell size and window size were prepared. • The W species were single-sited and tetrahedrally coordinated. • The content of the WV species evolved in parallel with that of the Pt2+ species. • The optimal Pt/W-MCFs catalyst gave a high 1,3-PDO yield of 63 %. • The WV species close to the Pt NPs may facilitate the immediate formation of 1,3-PDO. By varying the mass ratio of the swelling agent 1,3,5-trimethylbenzene (TMB) to the template P123 during the synthesis of the W-MCFs, we prepared a series of tungsten-doped siliceous mesocellular foams (W-MCFs) supported Pt catalysts (Pt/W-MCFs). In glycerol hydrogenolysis, the Pt/W-MCFs catalysts were highly active and selective to 1,3-propanediol (1,3-PDO), attributable to the 3-dimensional continuous large pore structure of the W-MCFs that facilitates the entry of the reactant and the escape of the product. Among the Pt/W-MCFs catalysts, the Pt/W-1.5MCFs catalyst with the TMB/P123 ratio of 1.5 exhibited the best activity and 1,3-PDO selectivity. Remarkably, the Pt/W-1.5MCFs catalyst afforded a high 1,3-PDO selectivity of 65 % at high glycerol conversion, thus rendering the highest 1,3-PDO yield of 63 %. The synergy between the Pt nanoparticles and the single-sited tetrahedral WVO 4 species at the metal–oxide interface is proposed to be responsible for the differences in the catalytic performances among the Pt/W-MCFs catalysts. [ABSTRACT FROM AUTHOR]

Plastics, fibers and rubber are three mainstream synthetic materials that are essential to our daily lives and contribute significantly to the quality of our lives. The production of the monomers of these synthetic polymers usually involves oxidation or ammoximation reactions of olefins and analogues. However, the utilization of C, O and N atoms in current industrial processes is <80%, which represents the most environmentally polluting processes for the production of basic chemicals. Through innovation and integration of catalytic materials, new reaction pathways, and reaction engineering, the Research Institute of Petroleum Processing, Sinopec Co., Ltd. (RIPP) and its collaborators have developed unique H 2 O 2 -centered oxidation/ammoximation technologies for olefins and analogues, which has resulted in a ¥500 billion emerging industry and driven trillions of ¥s' worth of downstream industries. The chemical and engineering bases of the production technologies mainly involve the integration of slurry-bed reactors and microsphere catalysts to enhance H 2 O 2 production, H 2 O 2 propylene/chloropropylene epoxidation for the production of propylene oxide/epichlorohydrin, and integration of H 2 O 2 cyclohexanone ammoximation and membrane separation to innovate the caprolactam production process. This review briefly summarizes the whole process from the acquisition of scientific knowledge to the formation of an industrial production technology by RIPP. Moreover, the scientific frontiers of H 2 O 2 production and related oxidation/ammoximation processes of olefins and analogues are reviewed, and new technological growth points are envisaged, with the aim of maintaining China's standing as a leader in the development of the science and technologies of H 2 O 2 production and utilization., (© The Author(s) 2024. Published by Oxford University Press on behalf of China Science Publishing & Media Ltd.)

The exfoliation of bulk C 3 N 4 (BCN) into ultrathin layered structure is an effective strategy to boost photocatalytic efficiency by exposing interior active sites and accelerating charge separation and transportation. Herein, we report a novel nitrate anion intercalation-decomposition (NID) strategy that is effective in peeling off BCN into few-layer C 3 N 4 (fl-CN) with tailored thickness down to bi-layer. This strategy only involves hydrothermal treatment of BCN in diluted HNO 3 aqueous solution, followed by pyrolysis at various temperatures. The decomposition of the nitrate anions not only exfoliates BCN and changes the band structure, but also incorporates oxygen species onto fl-CN, which is conducive to O 2 adsorption and hence relevant chemical processes. In photocatalytic O 2 reduction under visible light irradiation, the H 2 O 2 production rate over the optimal fl-CN-530 catalyst is 952 μmol g -1  h -1 , which is 8.8 times that over BCN. More importantly, under full arc irradiation and in the absence of hole scavenger, CH 4 can be photocatalytically oxidized by on-site formed H 2 O 2 and active oxygen species to generate value-added C1 oxygenates with high selectivity of 99.2 % and record-high production rate of 1893 μmol g -1  h -1 among the metal-free C 3 N 4 -based photocatalysts., (© 2024 Wiley‐VCH GmbH.)

Polymeric carbon nitride (PCN) is an important metal-free photocatalyst for visible light-driven hydrogen peroxide (H 2 O 2 ) production from O 2 reduction. Herein, we synthesized the DPCN catalysts possessing nitrogen defects by one-step thermal polymerization of urea in N 2 stream. As compared to the PCN conventionally synthesized in static air, X-ray photoelectrons spectroscopy (XPS) characterization disclosed that there are more pyridinic N defects in the DPCN catalysts, which is attributed to the removal of a proportion of NH 3 released from urea pyrolysis by flowing N 2 . UV-vis diffuse reflectance spectroscopy (UV-vis DRS), Mott-Schottky, steady-state and time-resolved photoluminescence (PL), and electrochemical impedance spectroscopy (EIS) characterizations revealed that the introduction of the nitrogen defects narrows down the band gap, improves the density of the photoexcited charge carriers, prolongs the lifetime of the charge carriers, and enhances the charge transfer efficiency. In visible light-driven photocatalytic O 2 reduction to H 2 O 2 , the optimal DPCN catalyst afforded an activity of 4.35 times that of the PCN catalyst and a H 2 O 2 concentration of 2.83 mmol L -1 after 10 h of visible light irradiation. This one-step thermal polymerization approach is valid when replacing N 2 stream with Ar and He streams., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier Inc. All rights reserved.)

Highly effective photocatalysts for the hydrogen-evolution reaction were developed by conferring the linkers of NH 2 -MIL-125(Ti), a metal-organic framework (MOF) constructed from TiO x clusters and 2-aminoterephthalic acid (linkers), with active copper centers. This design enables effective transfer of electrons from the linkers to the transient Cu 2+ /Cu + centers, leading to 7000-fold and 27-fold increase of carrier density and lifetime of photogenerated charges, respectively, as well as high-rate production of H 2 under visible-light irradiation. This work provides a novel design of a photocatalyst for hydrogen evolution using non-noble Cu 2+ /Cu + as co-catalysts., (© 2020 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

We devised iron-based catalysts with honeycomb-structured graphene (HSG) as the support and potassium as the promoter for CO 2 direct hydrogenation to light olefins (CO 2 -FTO). Over the optimal FeK1.5/HSG catalyst, the iron time yield of light olefins amounted to 73 μmol CO2 g Fe -1 s -1 with high selectivity of 59%. No obvious deactivation occurred within 120 h on stream. The excellent catalytic performance is attributed to the confinement effect of the porous HSG on the sintering of the active sites and the promotion effect of potassium on the activation of inert CO 2 and the formation of iron carbide active for CO 2 -FTO.