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Transition metal carbides of group 5 (G5TMC=VC, NbC and TaC) with similar crystallite sizes were prepared by a sol-gel route. The catalysts were characterized and studied in the methanol steam reforming (MSR) reaction in the temperature range of 573–723 K at atmospheric pressure and using a stoichiometric CH 3 OH/H 2 O = 1/1 mole ratio mixture. Under the MSR reaction conditions used, the route of methanol transformation depends on the G5TMC used as catalyst. The catalytic behaviour of VC differs from that of NbC and TaC, which in turn show a similar behaviour. Over VC, methanol is mainly converted to a mixture of H 2 +CH 4 , whereas over NbC and TaC the major product obtained is HCHO, formed from the dehydrogenation of methanol. • Group 5 transition metal carbides as catalysts in the methanol steam reforming. • Methanol steam reforming over VC, NbC and TaC polycrystalline catalysts. • H 2 +CH 4 mixtures are obtained under MSR over VC catalyst. • HCHO is obtained under MSR over NbC and TaC catalysts. [ABSTRACT FROM AUTHOR]

This paper reports the study of substoichiometric ethanol steam reforming (ESR) (H 2 O/ethanol = 1.6 mol ratio) for hydrogen production over new Ni/Y 2 O 3 La 2 O 3 ZrO 2 catalysts. ZrO 2 -based supports containing Y 2 O 3 and/or La 2 O 3 were prepared by precipitation using active carbon as the templating agent and the Ni-catalysts were then prepared by impregnation. CO 2 was used as regenerating agent and its effect was analysed as a function of the characteristics of the catalysts. The CO 2 treatment proved to be a powerful tool for regenerating deactivated Ni catalysts through mild oxidation of carbon deposits; this phenomenon is related to the basic characteristics of the catalysts. For Ni/12Zr29Y13La, a high H 2 yield and the smallest amount of poorly ordered carbon deposits were determined; full ethanol conversion was achieved during the last 50 h of a long-term (280 h) experiment with periodic CO 2 treatments. [ABSTRACT FROM AUTHOR]

In this study the promoter effect of Ga 2 O 3 in Cu-based catalysts for the methanol steam reforming reaction was examined. Ga-promoted Cu-based catalysts which had shown high performance in the CO 2 hydrogenation to methanol were studied in the methanol steam reforming at 493 K-593 K using CH 3 OH/H 2 O = 1/1.3 (mol/mol). Cu–Ga/ZnO at 593 K showed high catalytic performance to produce clean hydrogen. In situ DRIFTS-MS experiments of methanol steam reforming and CO 2 hydrogenation were performed over Cu–Ga/ZnO catalyst. A relationship between both processes is proposed through common surface formate species. [ABSTRACT FROM AUTHOR]

Al 2 O 3 -, MgO-, Y 2 O 3 -, La 2 O 3 - and ZrO 2 -supported Ni catalysts were prepared using supports obtained by precipitation in the presence of active carbon as a templating agent. The effect of CO 2 introduction as reactant on the ethanol steam reforming (ESR) was analysed as a function of the characteristics of the catalysts using H 2 O/ethanol = 1.6. The catalysts were characterized before and after their use in the CO 2 -assisted ethanol steam reforming (CDESR, ethanol/H 2 O/CO 2 = 1/1.6/1.6 mol ratio). For Ni/La 2 O 3 poorer structured carbon deposits were found after CDESR. Moreover, for Ni/Y 2 O 3 and Ni/La 2 O 3 the regeneration by CO 2 -treatment during ESR was studied. The CO 2 treatment partially restored their catalytic performance, CO 2 can act as a mild oxidant removing part of the carbonaceous deposits; this behaviour is related with the basic characteristics of the catalysts. [ABSTRACT FROM AUTHOR]

Abstract: The aim of this study was to investigate biohydrogen production from biofuel-reforming processes using new multi-component bulk-type cobalt-based catalysts. The addition of different components to improve the catalytic performance was studied. Monometallic cobalt catalyst and catalysts containing Ru (ca. 1%) and/or Na (ca. 0.5%) were characterized and tested in the 623–673K temperature range in ethanol steam reforming (ESR) with a steam/carbon ratio (S/C) of 3. The catalysts showed a high performance for hydrogen production and, except for H2 and CO2, only small amounts of by-products were obtained, depending on the temperature and the catalyst used. The catalyst containing both Ru and Na (Co–Ru(Na)) showed the best catalytic behavior in ESR. It operated stably for at least 12days under cycles of oxidative steam reforming of glycerol/ethanol mixtures (S/C=2) and activation under O2. [ABSTRACT FROM AUTHOR]

ZnO nanowires (NWs) with wurzite structure and a very high [0001] preferred orientation were grown on a ZnO thin film, from a gas-solid process, in the absence of catalyst. ZnO NWs were characterized by FESEM, XRD, HRTEM, XPS, PL and Raman spectroscopy and used as photocatalysts for the photo-transformation of ethanol (aq) in the gas phase. The existence of different defects such as oxygen vacancies was evidenced. The photocatalytic process was followed by in-situ diffuse reflectance infrared spectroscopy (DRIFTS) coupled to on-line mass spectrometry (MS) analysis. The surface species determined during the irradiation (λ = 365 nm) of ZnO NWs under ethanol/water vapor flow at room temperature are related with the hydrogen production and carbon-containing products evolved. • Hydrogen photoproduction from gas phase ethanol (aq) over ZnO nanowires. • Oxygen vacancies proposed in the 1D nanostructure of ZnO nanowires. • ZnO nanostructure controls the photocatalytic H 2 production from gas phase ethanol (aq). • Reaction pathways over ZnO NWs for H 2 and byproducts analyzed by in-situ DRIFTS. [ABSTRACT FROM AUTHOR]

In this paper, Pt/TiO 2 and Pt Ga/TiO 2 catalysts with similar Pt dispersion and similar structural and morphological characteristics were compared in the H 2 production from the phototransformation of aqueous solutions of ethanol. Catalysts were characterized by means of N 2 adsorption-desorption, XRD, Raman, H 2 -TPR, UV–Vis diffuse reflectance spectroscopy, XPS and CO chemisorption. The photocatalytic reaction was carried out in liquid and vapour phase. The photocatalytic transformation of ethanol (aq) vapour over Pt/TiO 2 and Pt Ga/TiO 2 catalysts was studied by in situ DRIFTS-MS. Differences in the photocatalytic transformation of ethanol (aq) over Pt/TiO 2 and Pt Ga/TiO 2 were determined. The effect of Ga is analysed in the light of the evolution of surface species under photocatalytic reaction conditions. [ABSTRACT FROM AUTHOR]

New CuOZnOxGa 2 O 3 –Al 2 O 3 and CuOZnOxGa 2 O 3 –ZrO 2 (CuZnxGaAl, CuZnxGaZr) catalysts with different Ga contents were prepared and tested in the methanol steam reforming reaction (MSR) under stoichiometric methanol/water = 1 mol ratio (S/C = 1) at 523 K and 548 K. Addition of Al 2 O 3 or ZrO 2 components increases the surface area and modifies the reducibility of CuOZnOGa 2 O 3 catalysts; the CuZnxGaZr systems showed the highest reducibility. The performance of CuOZnOGa 2 O 3 -based catalysts for MSR is improved by the presence of ZrO 2 promoter. CuZn3GaZr catalyst showed a high performance for MSR at 523 K and 548 K under stoichiometric conditions (S/C = 1). The catalyst resulted highly stable and selective for H 2 production, with formation of less than 0.3% mol of CO at 523 K. CO is produced as a secondary by-product through the reverse water gas shift reaction. The new catalysts show high resistance to carbon formation at the temperatures analyzed under stoichiometric conditions (S/C = 1). [ABSTRACT FROM AUTHOR]

Abstract: Oxidative steam reforming (OSR) of n-propanol was studied over new Ni catalysts (ca. 7% Ni wt/wt) supported on Y2O3–ZrO2 oxides with different yttrium content (2–41 % Y2O3 wt/wt). Materials were characterized by X-ray diffraction, temperature-programmed reduction, X-ray photoelectron and Raman spectroscopy, scanning electron microscopy with energy dispersive X-ray analysis and high resolution transmission electron microscopy. Samples were used in calcined form and tested in the temperature range 673–773 K using a reactant feed of n-propanol/water/O2 at a molar ratio 1/9/0.5. Hydrogen production is related with the support composition and Ni dispersion. [Copyright &y& Elsevier]

Abstract: The effect of iron promoter on cobalt-based catalysts, active in the ethanol steam-reforming, was studied. oxides prepared by co-precipitation and an Fe-doped prepared by wetness impregnation are analysed. The activation process of the oxides under reaction conditions was studied by in situ X-ray diffraction (XRD); the activation depended on the iron content of the oxides. The systems were characterized by means of temperature programmed reduction (TPR), XRD and tested in the ethanol steam-reforming reaction at 623–673K. An optimal iron loading that gives rise to a high H2selectivity and catalyst stability was determined. [Copyright &y& Elsevier]

[Display omitted] • New tailored nanoporous carbons from the common polypody for H 2 storage. • AC G-800 showing the highest H 2 uptake of 13.63 and 9.61 mmol/g at 0 and 25 °C under pressure of 45 bar. • Isosteric heat of adsorption values ranging from 5.7 to 7.7 kJ/mol indicate physisorption as the main adsorption mechanism. • G-800 sample shows exceptional cyclic stability and can be easily regenerated. This study presents the utilization of activated carbons (ACs) derived from Polypodium vulgare, a commonly available feedstock, for effective medium-pressure H 2 storage. For the ACs preparation, biomass was treated with KOH and then pyrolyzed at 700–900 °C. H 2 adsorption was performed at 25–100 °C and pressures up to 45 bar; nine different models (Langmuir, Freundlich, Temkin, Redlich–Peterson, Toth, Hill, Koble–Corrigan, Sips, and Radke–Prausnitz) were used for adjusting experimental H 2 adsorption isotherms. The micropore volume in the ranges 1.4–2 nm and 0.3–1.4 nm was determined by N 2 and CO 2 adsorption at −196 and 0 °C, respectively. The textural characteristics and the H 2 storage capacity of ACs depended on the carbonization temperature. All samples exhibited a considerable specific surface area of 1234–1591 m2/g, and significant volume of micropores with size below 1.4 nm. The H 2 adsorption capacity is related with the micropore volume determined by CO 2 adsorption. The AC prepared at 800 °C (G-800) showed the highest H 2 uptake and both the highest specific surface area and volume of micropores with size below 1.4 nm. G-800 adsorbs 13.63 mmol H 2 /g (2.73 wt%) at 25 °C and 45 bar. G-800 sample also showed exceptional cyclic stability, keeping its adsorption capabilities after undergoing multiple adsorption–desorption cycles. The isosteric heat of adsorption of ACs was determined using the Clausius-Clapeyron equation, yielding values ranging from 5.7 to 7.7 kJ/mol. [ABSTRACT FROM AUTHOR]

Abstract: This paper reports hydrogen production from oxidative steam reforming of 1-propanol and propylene glycol over Ni–M/Y2O3–ZrO2 (10% wt/wt Y2O3; M = Ir, Pt, Ru) bimetallic catalysts promoted with K. The results are compared with those obtained over the corresponding monometallic catalyst. The catalytic performance of the calcined catalysts was analyzed in the temperature range 723–773 K, adjusting the total composition of the reactants to O/C = 4 and S/C = 3.2–3.1 (molar ratios). The bimetallic catalysts showed higher hydrogen selectivity and lower selectivity of byproducts than the monometallic catalyst, especially at 723 K. Ni–Ir performed best in the oxidative steam reforming of both 1-propanol and propylene glycol. The presence of the noble metal favours the reduction of the NiO and the partial reduction of the support. The NiO crystalline phase present in the calcined catalysts was transformed to Ni° during oxidative steam reforming. The adsorption and subsequent reactivity of both 1-propanol and propylene glycol over Ni–Ir and Ni catalysts were followed by FTIR; C–C bond cleavage was found to occur at a lower temperature in propylene glycol than in 1-propanol. [Copyright &y& Elsevier]

Abstract: The use of lanthanum as a vanadium trap in USY-based catalysts was studied. Lanthanum was introduced in a HUSY zeolite by different methods: impregnation, precipitation and ionic exchange. Catalysts were characterized by means of XRD, XPS, FTIR, TEM and textural properties (surface-area and microporous volume). The catalysts were also tested in the catalytic reactions of 2-propanol dehydration and n-hexane cracking. The prevention of zeolite damage caused by vanadium depended on the lanthanum localization in the zeolite, which in turn was a function of the method of lanthanum introduction. Samples prepared by precipitation predominantly showed lanthanum species on the zeolite surface. On the other hand, when ionic exchange was used for the lanthanum introduction, it was located in the zeolite channels and cavities. The impregnation method produced a catalyst in which lanthanum was distributed on the zeolite surface but also in the channels and cavities and this catalyst showed a high tolerance to the vanadium presence, lower zeolite damage in steaming and less amount of acid sites poisoned by vanadium. [Copyright &y& Elsevier]