Slurry-phase CO2 hydrogenation to hydrocarbons over a precipitated Fe-Cu-Al/K catalyst: Investigation of reaction conditions

The hydrogenation of CO₂ to hydrocarbons over a precipitated Fe-Cu-Al/K catalyst was studied in a slurry reactor for the first time. Reducibility of the catalyst and effect of reaction variables (temperature, pressure and H₂/CO₂ ratio of the feed gas) on the catalytic reaction performance were investigated. The reaction results indicated that the Fe-Cu-Al/K catalyst showed a good CO₂ hydrogenation performance at a relatively low temperature (533 K). With the increase of reaction temperature CO₂ conversion and olefin to paraffin (O/P) ratio in C₂-C₄ hydrocarbons as well as the selectivity to C₂-C₄ fraction increased, while CO and CH₄ selectivity showed a reverse trend. With the increase in reaction pressure, CO₂ conversion and the selectivity to hydrocarbons increased, while the CO selectivity and O/P ratio of C₂-C₄ hydrocarbons decreased. The investigation of H2/CO₂ ratio revealed that CO₂ conversion and CH₄ selectivity increased while CO selectivity and O/P ratio of C₂-C₄ decreased with increasing H₂/CO₂ ratio.     

Catalytic syngas production from greenhouse gasses: Performance comparison of Ru-Al2O3 and Rh-CeO2 catalysts

In this work, 3% Ru-Al₂O₃ and 2% Rh-CeO₂ catalysts were synthesized and tested for CH₄-CO₂ reforming activity using either CO₂-rich or CO₂-lean model biogas feed. Low carbon deposition was observed on both catalysts, which negligibly influenced catalytic activity. Catalyst deactivation during temperature programmed reaction was observed only with Ru-Al₂O₃, which was caused by metallic cluster sintering. Both catalysts exhibited good stability during the 70 h exposure to undiluted equimolar CH₄/CO₂ gas stream at 750 °C. By varying residence time in the reactor during CH₄-CO₂ reforming, very similar quantities of H₂ were consumed for water formation. Reverse water-gas shift (RWGS) reaction occurred to a very similar extent either with low or high WHSV values over both catalysts, revealing that product gas mixture contained near RWGS equilibrium composition, confirming the dominance of WGS reaction and showing that shortening the contact time would actually decrease the H₂/CO ratio in the syngas produced by CH₄-CO₂ reforming, as long as RWGS is quasi equilibrated. H₂/CO molar ratio in the produced syngas can be increased either by operating at higher temperatures, or by using a feed stream with CH₄/CO₂ ratio well above 1.     

Simultaneous oxidative conversion and CO2 or steam reforming of methane to syngas over CoO–NiO–MgO catalyst

CO₂ reforming, oxidative conversion and simultaneous oxidative conversion and CO₂ or steam reforming of methane to syngas (CO and H₂) over NiO–CoO–MgO (Co: Ni: Mg=0·5: 0·5:1·0) solid solution at 700–850°C and high space velocity (5·1×10⁵ cm³ g⁻¹ h⁻¹ for oxidative conversion and 4·5×10⁴ cm³ g⁻¹ h⁻¹ for oxy-steam or oxy-CO₂ reforming) for different CH₄/O₂ (1·8–8·0) and CH₄/CO₂ or H₂O (1·5–8·4) ratios have been thoroughly investigated. Because of the replacement of 50 mol% of the NiO by CoO in NiO–MgO (Ni/Mg=1·0), the performance of the catalyst in the methane to syngas conversion process is improved; the carbon formation on the catalyst is drastically reduced. The CoO–NiO–MgO catalyst shows high methane conversion activity (methane conversion >80%) and high selectivity for both CO and H₂ in the oxy-CO₂ reforming and oxy-steam reforming processes at ⩾800°C. The oxy-steam or CO₂ reforming process involves the coupling of the exothermic oxidative conversion and endothermic CO₂ or steam reforming reactions, making these processes highly energy efficient and also safe to operate. These processes can be made thermoneutral or mildly exothermic or mildly endothermic by manipulating the process conditions (viz. temperature and/or CH₄/O₂ ratio in the feed). © 1998 Society of Chemistry Industry     

Electrochemical promotion of the CO2 hydrogenation reaction using thin Rh, Pt and Cu films in a monolithic reactor at atmospheric pressure

A monolithic electropromoted reactor (MEPR) with up to 22 thin Rh/YSZ/Pt or Cu/TiO₂/YSZ/Au plate cells was used to investigate the hydrogenation of CO₂ at atmospheric pressure and temperatures 220–380 °C. The Rh/YSZ/Pt cells lead to CO and CH₄ formation and the open-circuit selectivity to CH₄ is less than 5%. Both positive and negative applied potentials enhance significantly the total hydrogenation rate but the selectivity to CH₄ remains below 12%. The Cu/TiO₂/YSZ/Au cells produce CO, CH₄ and C₂H₄ with selectivities to CH₄ and C₂H₄ up to 80% and 2%. Both positive and negative applied potential significantly enhance the hydrogenation rate and the selectivity to C₂H₄. It was found that the addition of small (0.5 kPa) amounts of CH₃OH in the feed has a pronounced promotional effect on the reaction rate and selectivity of the Cu/TiO₂/YSZ/Au cells. The selective reduction of CO₂ to CH₄ starts at 220 °C (vs 320 °C in absence of CH₃OH) with near 100% CH₄ selectivity at open-circuit and under polarization conditions at temperatures 220–380 °C. The results show the possibility of direct CO₂ conversion to useful products in a MEPR via electrochemical promotion at atmospheric pressure.     

Autothermal reforming of methane to syngas with palladium catalysts and an electric metal monolith heater

The autothermal reforming of methane to syngas for use in the Fischer-Tropsch synthesis was studied in this work over PdO containing various combinations of CeO₂, BaO or SrO in a washcoated form on a metallic monolith at atmospheric pressure. This study focused on the autothermal operation of the system, in which an electric heater inside the reactor was used only to reach the ignition temperature, and thereafter the autothermal reaction successfully sustained itself without any external heat source. It was concluded from the experiments that the PdO/Al₂O₃ catalyst was better than the others, except for PdO-CeO₂-BaO-SrO/Al₂O₃, which showed similar performance in terms of the CH₄ conversion and H₂+CO selectivity, while affording a higher H₂/CO ratio (close to ca. 3) than the PdO/Al₂O₃ catalyst did (close to ca. 2). The gas hourly space velocity and O₂/CH₄ ratio governed the methane conversion, while the H₂O/CH₄ ratio controlled the H₂/CO ratio. A methane conversion of ∼87%, H₂+CO selectivity of ∼94%, H₂/CO ratio of ∼2.9, and M factor ∼2.15 were obtained under the conditions of a gas hourly space velocity (GHSV) of 120,000 h⁻¹, O₂/CH₄=0.6 and H₂O/CH₄=0.5.     

Tri-reforming of surrogate biogas over Ni/Mg/ceria–zirconia/alumina pellet catalysts

The performance of catalytic tri-reforming under industrially relevant situations (e.g., pellet catalysts, pressurized reactor) was investigated using surrogate biogas as the feedstock. Tri-reforming using Ni/Mg/Ce_0.6Zr_0.4O₂/Al₂O₃ pellet catalysts was studied in a bench scale fixed-bed reactor. The feed molar ratio for CH₄:CO₂:air was fixed as 1.0:0.70:0.95. The effects of temperature (800–860°C), pressure (1–6?bar), and H₂O/CH₄ molar feed ratio (0.23–0.65) were examined. Pressure has substantial impact on the reaction and transport rates and equilibrium conversions, making it a key variable. At 860°C, CO₂ conversion increased from 4 to 61% and H₂/CO molar ratio decreased from 2.0 to 1.1 as the pressure changed from 1 to 6?bar. CO₂ conversion and H₂/CO molar ratio were also influenced by the temperature and H₂O/CH₄ molar ratio. At 3?bar, CO₂ conversion varied between 4 and 43% and the H₂/CO molar ratio varied between 1.2 and 1.9 as the temperature changed from 800 to 860°C. At 3?bar and 860°C, CO₂ conversion decreased from 35 to 8% and H₂/CO molar ratio increased from 1.7 to 2.4 when the H₂O/CH₄ molar ratio was increased from 0.23 to 0.65. This work demonstrates that the tri-reforming technology is feasible for converting biogas under scaled-up conditions in a fixed-bed reactor.     

Partial oxidation of ethanol over Pd/CeO2 and Pd/Y2O3 catalysts

The effect of the support nature on the performance of Pd catalysts during partial oxidation of ethanol was studied. H₂, CO₂ and acetaldehyde formation was favored on Pd/CeO₂, whereas CO production was facilitated over Pd/Y₂O₃ catalyst. According to the reaction mechanism, determined by DRIFTS analyses, some reaction pathways are favored depending on the support nature, which can explain the differences observed on products distribution. On Pd/Y₂O₃ catalyst, the production of acetate species was promoted, which explain the higher CO formation, since acetate species can be decomposed to CH₄ and CO at high temperatures. On Pd/CeO₂ catalyst, the acetaldehyde preferentially desorbs and/or decomposes to H₂, CH₄ and CO. The CO formed is further oxidized to CO₂, which seems to be promoted on Pd/CeO₂ catalyst.     

Combined catalytic partial oxidation and CO2 reforming of methane over supported cobalt catalysts

The combined partial oxidation and CO₂ reforming of methane to synthesis gas was investigated over the reduced Co/MgO, Co/CaO, and Co/SiO₂ catalysts. Only Co/MgO has proved to be a highly efficient and stable catalyst. It provided about 94–95% yields to H₂ and CO at the high space velocity of 105000 mlg^–1h^–1 and for feed ratios CH₄/CO₂/O₂=4/2/1, without any deactivation for a period of study of 110 h. In contrast, the reduced Co/CaO and Co/SiO₂ provided no activity for the formation of H₂ and CO. The structure and reducibility of the calcined catalysts were examined using X-ray diffraction and temperature-programmed reduction, respectively. A solid solution of CoO and MgO, which was difficult to reduce, was identified in the 800°C calcined MgO-supported catalyst. The strong interactions induced by the formation of the solid solution are responsible for its superior activity in the combined reaction. The effects of reaction temperature, space velocity, and O₂/CO₂ ratio in the feed gases (while keeping the C/O ratio constant at 1/1) were investigated over the Co/MgO catalyst. The H₂/CO ratio in the product of the combined reaction increased with increasing O₂/CO₂ ratio in the feed.     

The effect of synthesis gas composition on the Fischer–Tropsch synthesis over Co/γ-Al2O3 and Co–Re/γ-Al2O3 catalysts

The Fischer–Tropsch synthesis over Co/γ-Al₂O₃ and Co–Re/γ-Al₂O₃ was investigated in a fixed-bed reactor at 20 bar and 483 K using feed gases with molar H₂/CO ratios of 2.1, 1.5 and 1.0 simulating synthesis gas derived from biomass. With lower H₂/CO ratios in the feed, the CO conversion and the CH₄ selectivity decreased, while the C₅₊ selectivity and olefin/paraffin ratio for C₂–C₄ increased slightly. The water–gas shift activity was low for both catalysts, resulting in high molar usage ratios of H₂/CO (close to 2.0), even at the lower inlet ratios (i.e. 1.5 and 1.0). For both catalysts, the drop in the production rate of hydrocarbons when shifting from an inlet ratio of 2.1 to 1.5 was significant mainly because the H₂/CO usage ratio did not follow the change in the inlet ratio. The hydrocarbon selectivities were rather similar for inlet H₂/CO ratios of 2.1 and 1.5, while significantly deviating from those for an inlet ratio of 1.0. With the studied catalysts, it is possible to utilize the advantages of an inlet ratio of 1.0 (higher selectivity to C₅₊, lower selectivity to CH₄, no water–gas shifting of the bio-syngas needed prior to the FT reactor) if a low syngas conversion is accepted.     

Pulse studies of CH4 interaction with NiO/Al2O3 catalysts

Pulse studies of the interaction of CH₄ and NiO/Al₂O₃ catalysts at 500°C indicate that CH₄ adsorption on reduced nickel sites is a key step for CH₄ oxidative conversion. On an oxygen-rich surface, CH₄ conversion is low and the selectivity of CO₂ is higher than that of CO. With the consumption of surface oxygen, CO selectivity increases while the CO₂ selectivity falls. The conversion of CH₄ is small at 500°C when a pulse of CH₄/O₂ (CH₄O₂=21) is introduced to the partially reduced catalyst, indicating that CH₄ and O₂ adsorption are competitive steps and the adsorption of O₂ is more favorable than CH₄ adsorption     

Reduction and oxidation properties of Fe2O3/ZrO2 oxygen carrier for hydrogen production

Fe₂O₃ is a promising oxygen carrier for hydrogen production in the chemical-looping process. A set of kinetic studies on reduction with CH₄, CO and H₂ respectively, oxidation with water and oxygen containing Ar for chemical-looping hydrogen production was conducted. Fe₂O₃ (20 wt.%)/ZrO₂ was prepared by a co-precipitation method. The main variables in the TGA (thermogravimetric analyzer) experiment were temperatures and gas concentrations. The reaction kinetics parameters were estimated based on the experimental data. In the reduction by CH₄, CO and H₂, the reaction rate changed near FeO. Changes in the reaction rate due to phase transformation were observed at low temperature and low gas concentration during the reduction by CH₄, but the phenomenon was not remarkable for the reduction by CO and H₂. The reduction rate achieved using CO and H₂ was relatively faster than achieved using CH₄. The Hancock and Sharp method of comparing the kinetics of isothermal solid-state reactions was applied. A phase boundary controlled model (contacting sphere) was applied to the reduction of Fe₂O₃ to FeO by CH₄, and a different phase boundary controlled model (contacting infinite slab) was fit well to the reduction of FeO to Fe by CH₄. The reduction of Fe₂O₃ to Fe by CO and H₂ can be described by the former phase boundary controlled model (contacting sphere). This phase boundary controlled model (contacting sphere) also fit well for the oxidation of Fe to Fe₃O₄ by water and FeO to Fe₂O₃ by oxygen containing Ar. These kinetics data could be used to design chemical-looping hydrogen production systems.     

Oxidative Reforming of Bio-Ethanol Over CuNiZnAl Mixed Oxide Catalysts for Hydrogen Production

Hydrogen (H₂) is expected to become an important fuel for the future to be used as an energy carrier in automobiles and electric power plants. A promising route for H₂ production involves catalytic reforming of a suitable primary fuel such as methanol or ethanol. Since ethanol is a renewable raw material and can be cheaply produced by the fermentation of biomass, the ethanol reforming for H₂ production is beneficial to the environment. In the present study, the steam reforming of ethanol in the presence of added O₂, which in the present study is referred to as oxidative steam reforming of ethanol (OSRE), was performed for the first time over a series of CuNiZnAl mixed oxide catalysts derived from layered double hydroxide (LDH) precursors. The effects of Cu/Ni ratio, temperature, O₂/ethanol ratio, contact time, CO co-feed and substitution of Cu/Ni by Co were investigated systematically in order to understand the influence of these parameters on the catalytic performance. An ethanol conversion close to 100% was noticed at 300 °C over all the catalysts. The Cu-rich catalysts favor the dehydrogenation of ethanol to acetaldehyde. The addition of Ni was found to favor the C–C bond rupture, producing CO, CO₂ and CH₄. Depending upon the reaction condition, a H₂ yield between 2.5 and 3.5 moles per mole of ethanol converted was obtained. A CoNi-based catalyst exhibited better catalytic performance with lower selectivity of undesirable byproducts, namely CH₃CHO, CH₄ and CO.     

High temperature SrCe0.9Eu0.1O3−δ proton conducting membrane reactor for H2 production using the water–gas shift reaction

The water–gas shift (WGS) reaction is used to shift the CO/H₂ ratio prior to Fischer–Tropsch synthesis and/or to increase H₂ yield. A WGS membrane reactor was developed using a mixed protonic–electronic conducting SrCe_0.9Eu_0.1O_3−δ membrane coated on a Ni–SrCeO_3−δ support. The membrane reactor overcomes the thermodynamic equilibrium limitations. A 46% increase in CO conversion and total H₂ yield was achieved at 900 °C under 3% CO and 6% H₂O, resulting in a 92% single pass H₂ production yield and 32% single pass yield of pure permeated H₂.     

Partial oxidation of methane to synthesis gas over corundum supported mixed oxides: One channel studies

Catalytic partial oxidation of methane (POM) over the monolithic catalyst LaNiO_x/CeO₂–ZrO₂/α-Al₂O₃ has been studied. Experiments were conducted with one channel of a monolith at a varied channel length, contact time (1–6 ms) and temperature using the diluted gas mixture (1% CH₄ + 0.5% O₂ in He). At increasing temperature and contact time, CO selectivity rises within the whole temperature range whereas the contact time dependence of H₂/CO ratio varies with the temperature. These results support the POM reaction scheme including primary formation of CO and H₂ followed by their oxidation in the presence of gas-phase O₂. Steam and dry methane reforming reactions occur in the part of monolithic channel where oxygen is absent, thus increasing syngas yield.     

Nature of Surface Deposits on Sulfated Zirconia Used as Catalyst in the Benzoylation of Anisole

The effects of CO₂, CO and H₂ co-reactants on CH₄ pyrolysis reactions catalyzed by Mo/H-ZSM-5 were investigated as a function of reaction temperatures and co-reactant and CH₄ concentrations. Total CH₄ conversion rates were not affected by CO₂ co-reactants, except at high CO₂ pressures, which led to the oxidation of the active MoC _x species, but CH _x intermediates formed in rate-determining C–H bond activation steps increasingly formed CO instead of hydrocarbons as CO₂ concentrations increased. CO formation rates increased with increasing CO₂ partial pressure; all entering CO₂ molecules reacted with CH₄ within the catalyst bed to form two CO molecules at 950-1033 K. In contrast, hydrocarbon formation rates decreased linearly with increasing CO₂ partial pressure and reached undetectable levels at CO₂/CH₄ ratios above 0.075 at 950 K. CO formation continued for a short period of time at these CO₂/CH₄ molar ratios, but then all catalytic activity ceased, apparently as a result of the conversion of active carbide structures to MoO _x . The removal of CO₂ from the CH₄ stream led to gradual catalyst reactivation via reduction-carburization processes similar to those observed during the initial activation of MoO _x /H-ZSM-5 precursors in CH₄. The CO₂/CH₄ molar ratios required to inhibit hydrocarbon synthesis were independent of CH₄ pressure because of the first-order kinetic dependencies of both CH₄ and CO₂ activation steps. These ratios increased from 0.075 to 0.143 as reaction temperatures increased from 950 to 1033 K. This temperature dependence reflects higher activation energies for reductant (CH₄) than for oxidant (CO₂) activation, leading to catalyst oxidation at higher relative oxidant concentrations as temperature increases. The scavenging of CH _x intermediates by CO₂-derived species leads also to lower chain growth probabilities and to a significant inhibition of catalyst deactivation via oligomerization pathways responsible for the formation of highly unsaturated unreactive deposits. CO co-reactants did not influence the rate or selectivity of CH₄ pyrolysis reactions on Mo/H-ZSM-5; therefore, CO formed during reactions of CO₂/CH₄ mixtures are not responsible for the observed effects of CO₂ on reaction rates and selectivities, or in catalyst deactivation rates during CH₄ reactions. H₂ addition studies showed that H₂ formed during CH₄/CO₂ reactions near the bed inlet led to inhibited catalyst deactivation in downstream catalyst regions, even after CO₂ co-reactants were depleted.     

Integrated coal pyrolysis with CO2 reforming of methane over Ni/MgO catalyst for improving tar yield

A new process to integrate coal pyrolysis with CO₂ reforming of methane over Ni/MgO catalyst was put forward for improving tar yield. And several Chinese coals were used to confirm the validity of the process. The experiments were performed in an atmospheric fixed-bed reactor containing upper catalyst layer and lower coal layer to investigate the effect of pyrolysis temperature, coal properties, Ni loading and reduction temperature of Ni/MgO catalysts on tar, water and char yields and CH₄ conversion at fixed conditions of 400 ml/min CH₄ flow rate, 1:1 CH₄/CO₂ ratio, 30 min holding time. The results indicated that higher tar yield can be obtained in the pyrolysis of all four coals investigated when coal pyrolysis was integrated with CO₂ reforming of methane. For PS coal, the tar, water and char yield is 33.5, 25.8 and 69.5 wt.%, respectively and the CH₄ conversion is 16.8%, at the pyrolysis temperature of 750 °C over 10 wt.% Ni/MgO catalyst reduced at 850 °C. The tar yield is 1.6 and 1.8 times as that in coal pyrolysis under H₂ and N₂, respectively.     

Fischer�CTropsch Synthesis: Influence of CO Conversion on Selectivities, H2/CO Usage Ratios, and Catalyst Stability for a Ru Promoted Co/Al2O3 Catalyst Using a Slurry Phase Reactor

The effect of CO conversion on hydrocarbon selectivities (i.e., CH₄, C₅₊, olefin and paraffin), H₂/CO usage ratios, CO₂ selectivity, and catalyst stability over a wide range of CO conversion (12?C94%) on 0.27%Ru?C25%Co/Al₂O₃ catalyst was studied under the conditions of 220 °C, 1.5 MPa, H₂/CO feed ratio of 2.1 and gas space velocities of 0.3?C15 NL/g-cat/h in a 1-L continuously stirred tank reactor (CSTR). Catalyst samples were withdrawn from the CSTR at different CO conversion levels, and Co phases (Co, CoO) in the slurry samples were characterized by XANES, and in the case of the fresh catalysts, EXAFS as well. Ru was responsible for increasing the extent of Co reduction, thus boosting the active site density. At 1%Ru loading, EXAFS indicates that coordination of Ru at the atomic level was virtually solely with Co. It was found that the selectivities to CH₄, C₅₊, and CO₂ on the Co catalyst are functions of CO conversion. At high CO conversions, i.e. above 80%, CH₄ selectivity experienced a change in the trend, and began to increase, and CO₂ selectivity experienced a rapid increase. H₂/CO usage ratio and olefin content were found to decrease with increasing CO conversion in the range of 12?C94%. The observed results are consistent with water reoxidation of Co during FTS at high conversion. XANES spectroscopy of used catalyst samples displayed spectra consistent with the presence of more CoO at higher CO conversion levels.     

Study of ruthenium supported on Ta2O5–ZrO2 and Nb2O5–ZrO2 as catalysts for the partial oxidation of methane

Ru-based catalysts supported on Ta₂O₅–ZrO₂ and Nb₂O₅–ZrO₂ are studied in the partial oxidation of methane at 673–873 K. Supports with different Ta₂O₅ or Nb₂O₅ content were prepared by a sol–gel method, and RuCl₃ and RuNO(NO₃)₃ were used as precursors to prepare the catalysts (ca. 2 wt.% Ru). At 673 K high selectivity to CO₂ was found. An increase of temperature up to 773 K produced an increase in the selectivity to syngas (H₂/CO = 2.2–3.1), and this is related with the transformation of RuO₂ to metallic Ru as was determined from XRD and XPS results. At 873 K and with co-fed CO₂ an increase of the catalytic activity and CO selectivity was found. A TOF value of 5.7 s⁻¹ and H₂/CO ratio ca. 1 was achieved over Ru(Cl)/6TaZr. Catalytic results are discussed as a function of the support composition and characteristics of Ru-based phases.     

Partial oxidation of methane to syngas over Ni/MgO, Ni/CaO and Ni/CeO2

Partial oxidation of methane to syngas at atmospheric pressure and 750°C was examined over Ni/MgO, Ni/CaO and Ni/CeO₂ catalysts with nickel loading of 13 wt%. All catalysts had similar high conversion of methane and high selectivity to syngas, which nearly approached the values predicted by thermodynamic equilibrium. However, only Ni/MgO showed high resistance to carbon deposition under thermodynamically severe conditions (CH₄/O₂ = 2.5, a higher CH₄ to O₂ ratio than the stoichiometric ratio). Its catalytic activity remained stable during 100 h of reaction, with no detectable carbon deposition. The oxidation of carbon deposited from pure CH₄ decomposition and from pure CO disproportionation was investigated by in situ TPO-MS study which showed that both were effectively inhibited over Ni/MgO. In addition, the catalysts were characterized by TPR, XRD and XPS. It was revealed that the excellent performance of Ni/MgO resulted from the formation of an ideal solid solution between NiO and MgO. This revised version was published online in August 2006 with corrections to the Cover Date.     

Low-temperature reforming of ethanol over CeO2-supported Ni-Rh bimetallic catalysts for hydrogen production

A new series of Ni-Rh bimetallic catalysts with different Ni and Rh loadings on a high-surface-area CeO₂ was developed for the reforming of bio-ethanol at low-temperature (below 450 °C) to produce H₂-rich gas for on-site or on-board fuel cell applications. Oxidative steam reforming of ethanol (OSRE) over a Ni-Rh/CeO₂ catalyst containing 5 wt% Ni and 1 wt% Rh was found to be more efficient offering about 100% ethanol conversion at 375 °C with high H₂ and CO₂ selectivity and low CO selectivity compared to the steam reforming of ethanol (SRE) reaction which required a higher temperature of about 450 °C to achieve 100% ethanol conversion. The high temperature SRE reaction favors the formation of large amount of CO, which would make the downsteam CO cleanup more complicated for polymer electrolyte membrane fuel cell (PEMFC). The presence of O₂ in the feed gas was found to greatly enhance the conversion of ethanol to produce H₂ and CO₂ as major products. Increase in Ni content above 5 wt% in the catalyst formulation decreased the H₂ selectivity while the selectivity of undesirable CH₄ and acetaldehyde increased. The 1 wt% Rh/CeO₂ catalyst was twice as active as 10 wt% Ni/CO₂ catalyst in terms of ethanol conversion and acetaldehyde selectivity and this indicated that Rh was more effective in C–C bond cleavage than Ni. The reaction was found to proceed through the formation of acetaldehyde intermediate, which subsequently underwent decomposition to produce a mixture of CO and CH₄ or reforming with H₂O and O₂ to produce CO, CO₂ and H₂. The role of Rh is mainly to cleave the C–C and C–H bonds of ethanol to produce H₂ and COx while Ni addition helps converting CO into CO₂ and H₂ by WGS reaction under the conditions employed.