Combined steam reforming of methanol over Cu–Mn spinel oxide catalysts (original) (raw)
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Steam reforming of methanol over copper–manganese spinel oxide catalysts
Catalysis Communications, 2005
The steam reforming of methanol was studied over a series of copper-manganese spinel oxide catalysts prepared with the ureanitrate combustion method. All catalysts showed high activity towards H 2 production with high selectivity. Synthesis parameters affected catalyst properties and, among the catalysts tested, the one prepared with 75% excess of urea and an atomic ratio Cu/ (Cu + Mn) = 0.30 showed the highest activity. The results show that formation of the spinel Cu x Mn 3 À x O 4 phase in the oxidized catalysts is responsible for the high activity. Cu-Mn catalysts were found to be superior to CuO-CeO 2 catalysts prepared with the same technique.
Cu−Cr, Cu−Mn, and Cu−Fe Spinel-Oxide-Type Catalysts for Reforming of Oxygenated Hydrocarbons
Effective hydrogen production is achieved via steam reforming of the oxygenated hydrocarbons, including methanol and dimethyl ether, over Cu-based spinel-oxide catalysts. CuFe 2 O 4 , CuMn 2 O 4 , and CuCr 2 O 4 were wellcrystallized in spinel structures and were provided with low specific surface areas below 2 m 2 g −1 . Upon reduction, the spinels possessed Cu + -rich surfaces when compared with a commercial Cu/ZnO/Al 2 O 3 , which resulted in better catalytic performance in methanol steam reforming (MSR). The composite catalysts of the Cu spinel and γ-Al 2 O 3 were promising for dimethyl ether steam reforming (DMESR) in terms of activity, selectivity, and stability. The descending order of the DMESR activity over the composite catalysts was as follows: CuFe , which was in line with the MSR activity over Cu−spinel catalysts. This revealed that the MSR activity strongly contributed to the high DMESR activity using the composite Cu−spinel catalysts and γ-Al 2 O 3 . The theoretical calculations demonstrated that the observed MSR reactivity trend follows the reactivity of the MSR rate-limiting step of methoxy dehydrogenation. The required active sites are shown to be both Cu and metal oxide in the facilitation of methoxy dehydrogenation.
Methanol steam reforming; Effects of various metal oxides on the properties of a Cu-based catalyst
2016
Ternary Cu/ZnO/metal oxide catalysts are prepared through the co-precipitation method under strict control of parameters like pH, calcination conditions, and precipitation temperature in a systematic manner. The metal oxides applied in this study consist of Al2O3, ZrO2, La2O3 and Ce2O3. The distinction of this work in comparison with similar research is a comprehensive investigatation of the catalytic properties of metal oxides (including conversion, selectivity and stability) which have the potential for use in the methanol steam reforming process. The catalysts are characterized through XRD, SEM and BET. The prepared catalysts are applied in methanol steam reforming in a fixed bed reactor. A TGA analysis performed for all four catalysts determined that the Ce2O3 and ZrO2 metal oxide catalysts showed the best results in terms of stability with a coke formation of 0.7wt% and 0.8wt%, respectively; and maximum surface area is related to Cu/ZnO/Ce2O3, which can result in excellent s...
Applied Catalysis B: Environmental, 2007
Cu/ZnO/Al 2 O 3 catalysts (5-45 Cu at.%) derived from layered double hydroxide (LDH) precursors were studied for oxidative steam reforming of methanol (OSRM). The precursors were prepared by homogeneous precipitation with urea. The catalysts were obtained by thermal decomposition of the precursors and subsequent reduction in H 2 stream. XRD, SEM, N 2 adsorption, TPR and NH 3 TPD techniques were employed for characterization. Catalytic activity tests were carried out in a fixed bed flow reactor at T = 200-400 8C, H 2 O/CH 3 OH/O 2 molar ratios = 1.1/1/0.12 (CH 3 OH concentration = 17.8%), GHSV = 6 Â 10 4 h À1 . Tests of simple steam reforming (SRM), partial oxidation (POM) and CH 3 OH decomposition (DEC) were also carried out. TPR measurements showed that redox properties depended on the composition of the samples and on the nature of the phases present in the precursors. The area of metallic Cu, measured by N 2 O passivation method, was correlated to Cu content. The size of Cu particles was smaller than 10 nm for Cu content up to 18 at.%. NH 3 TPD measurements showed acid sites with a wide strength distribution, the strongest ones being mainly related to Al 2 O 3 or Zn aluminate. Catalytic activity was influenced by the chemical composition: kinetic constants for OSRM varied unevenly with Cu surface area, while those for SRM increased with Cu surface area. A reaction mechanism agreeing with OSRM, SRM and DEC data was hypothesized. The mechanism involved an oxidation-reduction cycle of Cu and also the participation of the oxide matrix. #
2007
Cu/ZnO/Al2O3 catalysts with different composition, prepared from LDH precursors, are studied for OSRM. The catalysts are characterizad by XRD, N2 adsorption and TPR techniques. N2O passivation/TPR method is used for the measurement of Cu dispersion. Redox properties are greatly influenced by the chemical composition. Cu dispersion is a function of Cu content: nanosized Cu particles are present up to Cu content of 18at.%. Catalytic activity appears not simply related to Cu content or Cu surface area. A role of the dispersing oxide matrix on the catalytic activity is hypothesized.
Intensification of methanol steam reforming process using Cu-modified Ni-based supported catalysts
2019
Hydrogen is conventionally manufactured in large scale by the steam reforming of methane or naphthas. The perspective of using hydrogen as a fuel depends of finding alternatives to the existing production technologies and feedstock. Oxygenated compounds are an interesting alternative and are been investigated extensively [1]. The process of steam reforming of mixtures of oxygenated hydrocarbons does not contribute to a net increase in atmospheric CO2, as oxygenated obtained from renewable resources are considered to be CO2 neutral. In previous works has been demonstrate that Steam Reforming of oxygenated compounds is a complex reactions network where in a previous step, decomposition reaction take place followed by the reforming of decomposition products. Its known that DME (or methanol) receives particular attention due to its properties similar to those of liquefied petroleum gas (LPG)and it can be used as a clean high-efficiency compression ignition fuel with reduced NOx, SOx, an...
Production of hydrogen via combined steam reforming of methanol over CuO–CeO 2 catalysts
Catalysis Communications, 2004
Hydrogen production by (combined) steam reforming of methanol (CSRM) was investigated over CuO-CeO 2 catalysts prepared via the urea-combustion method. The characteristics of the resulting oxides were strongly influenced by the autoignition time during synthesis and the sample prepared with near stoichiometric quantity of urea had less favorable catalytic properties. Catalysts prepared from urea-rich or lean mixtures were more active and selective and an optimum behavior was obtained with 75% excess of urea and Cu/(Cu + Ce) ratio equal to 0.15. The higher methanol conversion in the CSRM process may be attributed to more efficient heat transfer in the bed due to combustion of part of methanol.
Oxy-steam reforming of methanol on copper catalysts
Reaction Kinetics, Mechanisms and Catalysis
The influence of copper content in the monometallic catalysts supported on the CeO 2 •Al 2 O 3 binary oxide system on their catalytic activity and physicochemical properties in oxy-steam reforming of methanol was investigated. It was shown that activity and selectivity depends on the content of copper, its dispersion on the catalysts surface. It was confirmed that optimal copper content was 20 wt% of Cu. Copper catalysts with 20 wt% of Cu exhibited the highest methanol conversion and reaction rate value compared to the rest of the investigated catalysts systems. The kinetic measurements performed in oxy-steam reforming of methanol on 20%Cu/CeO 2 •Al 2 O 3 catalysts, showed an activation energy for this system equal Ea (OSRM) = 66.56 kJ/mol.