The effect of catalyst formulation and Rh dispersion on the performance of a CPO fuel processor investigated by operando sampling technique and predictive modelling analysis

The catalytic partial oxidation (CPO) of methane and iso-octane on Rh-coated monoliths is studied in an adiabatic reactor where axial temperature and concentration profiles are collected by a spatially resolved sampling technique. In CH₄-CPO, the Rh/MgAl₂O₄ outperforms the Rh/α-Al₂O₃ formulation, due to a significant improvement of Rh dispersion. In iso-octane CPO, the beneficial effect of the improved Rh surface is less important due to the intrinsic lower sensitivity of the system. However, a non-negligible impact of Rh dispersion on the extent of hydrocarbon side-products is observed. This factor, together with the lower acidity of the spinel support, contributes to limit the C build-up. Reactor model and kinetic schemes allow to rationalize the measurements and explore the more general effect of Rh specific surface on the key performance indicators of the CPO reformer, that is syngas productivity and hot-spot temperature. Gas-solid diffusion rate makes such indicators strictly fuel-specific.     

Steam reforming of iso-octane toward hydrogen production over mono- and bi-metallic Cu–Co/CeO2 catalysts: Structure-activity correlations

Τhe feasibility of tailoring the iso-octane steam reforming activity of Cu/CeO₂ catalysts through the use of Co as a second active metal (Cu_20−xCo_x, where x = 0, 5, 10, 15, 20 wt%), is investigated. Characterization studies, involving N₂ adsorption–desorption at −196 °C (BET), X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), X-ray Photoelectron Spectroscopy (XPS) and Temperature Programmed Reduction (H₂-TPR), were carried out to reveal the impact of the morphological, structural and surface properties of the catalysts on the reforming performance. The results showed that reforming activity was monotonically increased upon increasing cobalt loading. The Co/CeO₂ catalyst demonstrated the optimum performance with a H₂ yield of 70–80% in the 600–800 °C temperature interval. The Co/CeO₂ catalyst exhibited also excellent stability at temperatures above 700 °C, while Cu-based catalysts rapidly deactivated in long term stability tests. A close correlation between surface/redox properties and steam reforming efficiency was established. The lower reducibility of Co/CeO₂ catalysts, associated with the formation of Co³⁺ species, in Co₃O₄-like phase, can be accounted for the enhanced carbon tolerance of Co-based catalysts. Furthermore, the high concentration of surface oxygen species on Co/CeO₂ catalysts can be considered for their enhanced performance. On the other hand, the Cu-induced easier reducibility of bimetallic catalysts, in conjunction with carbon deposition and active phase sintering can be accounted for their inferior steam reforming performance. Irreversible changes in the redox properties of Cu-based catalysts, taking place under reaction conditions, could be resulted to ceria deactivation thus hindering the redox process to keep on.     

Steam reforming of ethanol on Rh/SiCeO2 washcoated monolith catalyst: Stable catalyst performance

The performance of a new Rh/CeSiO₂ catalyst supported on a ceramic monolith for steam reforming (SR) of ethanol for hydrogen generation was investigated. It provides several advantages over a traditional pellet based catalyst in that it will reduce weight, size and pressure drop in the reactor. The effect of steam to ethanol molar ratio and temperature were first investigated on a powdered catalyst in order to establish the preferred reaction conditions to be used for tests on the monolith. The optimum temperature for coke free, high selectivity and stable catalyst operation was 1073 K at a steam to ethanol molar ratio of 3.5. The monolith supported catalyst was evaluated for aging stability, on/off performance and coke regeneration using steam gasification. After 96 h of SR of ethanol at 1028 K and water/ethanol molar ratio of 3.5 the monolith supported catalyst retained stable performance throughout the entire time on stream with the only products being H₂, CO, CO₂. Some coke formation was observed using Raman spectra, however, it did not cause any permanent deactivation. Regeneration via steam gasification at 973 K with 20% steam in N₂ was successful for coke removal and complete catalyst regeneration.     

Steam reforming of hot gas from gasified wood types and miscanthus biomass

The reforming of hot gas generated from biomass gasification and high temperature gas filtration was studied in order to reach the goal of the CHRISGAS project: a 60% of synthesis gas (as x(H₂)+ x(CO) on a N₂ and dry basis) in the exit gas, which can be converted either into H₂ or fuels. A Ni-MgAl₂O₄ commercial-like catalyst was tested downstream the gasification of clean wood made of saw dust, waste wood and miscanthus as herbaceous biomass. The effect of the temperature and contact time on the hydrocarbon conversion as well as the characterization of the used catalysts was studied. Low (<600 °C), medium (750°C–900 °C) and high temperature (900°C–1050 °C) tests were carried out in order to study, respectively, the tar cracking, the lowest operating reformer temperature for clean biomass, the methane conversion achievable as function of the temperature and the catalyst deactivation. The results demonstrate the possibility to produce an enriched syngas by the upgrading of the gasification stream of woody biomass with low sulphur content. However, for miscanthusthe development of catalysts with an enhanced resistance to sulphur poison will be the key point in the process development.     

Catalyst deactivation and regeneration during CO2 reforming of bio-oil

Catalyst deactivation and regeneration during CO₂ reforming of bio-oil were researched in this paper. The results of XRD, TG and SEM analyses showed that the catalyst deactivation was a combination of carbon deposition and sintering. There were amorphous carbon and filamentous carbon on the catalyst surface, but amorphous carbon was the main carbon product, which was the main reason for the catalyst deactivation. The activity and stability of steam regeneration catalyst is superior to that of CO₂ and air regeneration catalyst, but steam regeneration process will consume much quantity of steam, which can be increased production cost. Air regeneration method is easy to sinter the center of catalyst. CO₂ regeneration process not only produces useful gases (C + CO₂ = 2CO), but also makes good use of greenhouse gases, which has an industrial application prospect. However, with the cycle of catalyst increasing, the activity and stability catalyst will decrease gradually during the CO₂ reforming process.     

Study of a CeZrCoRh mixed oxide for hydrogen production by ethanol steam reforming

The catalytic activity of Ce₂Zr_1.5Co_0.47Rh_0.07O_8−δ oxide has been studied in the reaction of ethanol steam reforming. The catalyst has been characterised by XRD, SEM, TEM-EDXS, IR operando, TPR and TPO techniques. The results show that there are three main causes of catalyst deactivation. The first one is the accumulation of carbonates species leading to the blocking of active sites. This phenomenon is partially reversible by high temperature treatment under inert gas flow. The second deactivation mechanism is the formation of carbonaceous deposits. It has been shown to be directly proportional to the quantity of ethanol converted during the ethanol steam reforming, and produced with a constant selectivity whatever the ethanol conversion level, it is irreversible by thermal cleaning. The third way of deactivation arises from a structural change of the catalyst under the reaction conditions, which gradually loses its redox capacity.     

Characterization and activity test of commercial Ni/Al2O3, Cu/ZnO/Al2O3 and prepared Ni–Cu/Al2O3 catalysts for hydrogen production from methane and methanol fuels

In this study, methane and methanol steam reforming reactions over commercial Ni/Al₂O₃, commercial Cu/ZnO/Al₂O₃ and prepared Ni–Cu/Al₂O₃ catalysts were investigated. Methane and methanol steam reforming reactions catalysts were characterized using various techniques. The results of characterization showed that Cu particles increase the active particle size of Ni (19.3 nm) in Ni–Cu/Al₂O₃ catalyst with respect to the commercial Ni/Al₂O₃ (17.9). On the other hand, Ni improves Cu dispersion in the same catalyst (1.74%) in comparison with commercial Cu/ZnO/Al₂O₃ (0.21%). A comprehensive comparison between these two fuels is established in terms of reaction conditions, fuel conversion, H₂ selectivity, CO₂ and CO selectivity. The prepared catalyst showed low selectivity for CO in both fuels and it was more selective to H₂, with H₂ selectivities of 99% in methane and 89% in methanol reforming reactions. A significant objective is to develop catalysts which can operate at lower temperatures and resist deactivation. Methanol steam reforming is carried out at a much lower temperature than methane steam reforming in prepared and commercial catalyst (275–325 °C). However, methane steam reforming can be carried out at a relatively low temperature on Ni–Cu catalyst (600–650 °C) and at higher temperature in commercial methane reforming catalyst (700–800 °C). Commercial Ni/Al₂O₃ catalyst resulted in high coke formation (28.3% loss in mass) compared to prepared Ni–Cu/Al₂O₃ (8.9%) and commercial Cu/ZnO/Al₂O₃ catalysts (3.5%).     

A comparative study of dry reforming of methane over nickel catalysts supported on perovskite-type LaAlO3 and commercial α-Al2O3

A systematic and comparative study was made to determine the influence of perovskite-type LaAlO₃ and commercial α-Al₂O₃ on the performance of nickel-based catalysts in dry reforming of methane (DRM). The perovskite-type LaAlO₃ was selected due to its characteristics of solid state semiconductor with oxygen vacancies and high structural stability. The catalysts were characterized by X-ray diffraction (XRD), X-ray fluorescence spectroscopy (XRF), N₂ adsorption-desorption, temperature programmed reduction (TPR-H₂), thermogravimetric analysis (TGA), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The catalyst performance was evaluated based on activity tests (600–800 °C) and short- and long-term stability (10 and 20 h) at 700 °C at a GHSV (Gas Hourly Space Velocity) of 18 and 72 L g^?1 h^?1. The TPR-H₂ profiles indicate that the oxygen vacancies on the perovskite surface exerted a strong effect on the reduction temperature and reducibility of the NiO nanoparticles, resulting in weak Ni⁰/support interaction. The results of the tests after 10 h under GHSV of 18 L g^?1 h^?1 indicate that the Ni/LaAlO₃ catalyst is 7.8 and 11.5% more stable than Ni/α-Al₂O₃ in the conversions of CH₄ and CO₂, respectively. The higher stability and activity of Ni/LaAlO₃ is directly ascribed to the presence of NiO (3.38 wt%) after activation, which promoted the formation of carbon nanotubes (CNT) and increased the dispersion of the metallic phase. Even under severe conditions of activation and reaction (high GHSV), as in the long-term test, the Ni/LaAlO₃ catalyst showed a 37.2% higher H₂ yield than the Ni/α-Al₂O₃. Analyses by TEM indicate that the Ni/α-Al₂O₃ catalyst exhibited deactivation problems associated with sintering effects. Thus, the presence of structural defects and surfaces rich in oxygen vacancies makes LaAlO₃ perovskite a potential support for application in methane catalytic reforming processes.     

Nickel based catalysts for methane dry reforming: Effect of supports on catalytic activity and stability

Methane dry reforming (MDR) is a promising process for syngas production through the valorisation of two of the main Greenhouse gases. Despite the high endothermicity, it should be carried out at low temperature to directly use the syngas for Fischer-Tropsch reaction and oxygenated chemical production. The catalyst plays a key role in this process as it must encourage syngas formation by limiting coke deactivation. This work focusses the attention on the effect of different supports in the activity and stability of nickel-based catalysts. In particular, MDR has been studied at relatively low temperature, 500 °C, to deeply investigate how the support influences the reaction pathway. Ceria, zirconia, alumina, silica and titania were considered and the morphological and structural features of the materials were analysed via N₂-physisorption, AAS, TPR, XRD, CO₂-TPD, and SEM techniques. Moreover, by analysing the spent catalysts, it was possible to identify the causes of catalysts deactivation. Titania based catalyst is not active for MDR, while silica and zirconia present moderated activity due to the poor support stability. Most promising results are obtained with ceria and alumina-based catalysts; for these materials, 70-h reaction was carried out and alumina catalyst has proved to be the most stable towards MDR at low reaction temperature with a stable H₂ yield of 25% .     

On the dynamics and reversibility of the deactivation of a Rh/CeO2ZrO2 catalyst in raw bio-oil steam reforming

The deactivation mechanism of a commercial Rh/CeO₂ZrO₂ catalyst in raw bio-oil steam reforming has been studied by relating the evolution with time on stream of the bio-oil conversion and products yields and the physicochemical properties of the deactivated catalyst studied by XRD, TPR, SEM, XPS, TPO and TEM. Moreover, the reversibility of the different deactivation causes has been assessed by comparing the behavior and properties of the catalyst fresh and regenerated (by coke combustion with air). The reactions were carried out in an experimental device with two units in series: a thermal treatment unit (at 500 °C, for separation of pyrolytic lignin) and a fluidized bed reactor (at 700 °C, for the reforming reaction). The results evidence that structural changes (support aging involving partial occlusion of Rh species) are irreversible and occur rapidly, being responsible for a first deactivation period, whereas encapsulating coke deposition (with oxygenates as precursors) is reversible and evolves more slowly, thus being the main cause of the second deactivation period. The deactivation selectively affects the reforming of oxygenates, from least to greatest reactivity. Rh sintering is not a significant deactivation cause at the studied temperature.     

Effect of sulphur during the catalytic partial oxidation of ethane over Rh and Pt honeycomb catalysts

The impact of sulphur addition (2–58 ppm) during the catalytic partial oxidation (CPO) of ethane was investigated on Rh- and Pt-based honeycomb catalysts tested under self-sustained high temperature conditions. Both steady state and transient operation of the CPO reactor were investigated particularly with regards to poisoning/regeneration cycles. A detailed analysis of products distribution in the effluent and a heat balance of the CPO reactor demonstrates that sulphur reversibly adsorbed on Rh selectively inhibits the ethane hydrogenolysis and, to a lower extent, steam reforming reaction. A further, simultaneous adverse effect of S on the kinetics of the reverse water gas shift reaction on Rh catalyst operating at temperatures < 750 °C can cause an unexpected increase in the H₂ yield above its equilibrium value for low concentrations of the poison. Pt catalyst is less active for those reactions but in turn is more S-tolerant.     

A model of steam reforming of iso-octane: The effect of thermal boundary conditions on hydrogen production and reactor temperature

Steam reforming of iso-octane in a monolithic type reactor was simulated by a three-dimensional computational fluid dynamics model. The variations of hydrogen production and reactor temperature along the length of the reactor were calculated at isothermal, adiabatic and constant heat flux conditions. The reaction rate expressions based on steam reforming of methane in the Langmuir-Hinshelwood format were used to model steam reforming of iso-octane. The difference between the simulated results and experimental data on hydrogen produced was less than 18%. The results indicated that a large drop in temperature was in the first one-tenth of the reactor under adiabatic conditions with inlet temperatures of 600–900 °C. To achieve the same mole fraction of hydrogen (0.27, dry basis) at the exit of the reactor, the maximum temperature difference across the reactor was much smaller at certain heat flux conditions than that at adiabatic conditions. Further, rate of hydrogen production may be evenly distributed in the reactor under certain conditions of constant heat flux.     

Effect of N2O-mediated calcination on nickel species and the catalytic activity of nickel catalysts supported on γ-Al2O3 in the steam reforming of glycerol

The steam reforming of glycerol over supported nickel catalysts is a promising and cost-effective method for producing hydrogen. The activity of nickel catalysts supported on γ-Al₂O₃ is low, primarily due to the formation of inactive nickel species during high temperature calcination in air. In order to address this problem, a Ni/γ-Al₂O₃ catalyst was prepared by calcination at 700 °C in a nitrous oxide (N₂O) environment. The N₂O calcined catalyst showed an enhanced activity for the steam reforming of glycerol. A variety of characterization techniques (XRD, TPR, XPS and H₂ Chemisorption) confirmed that the high temperature N₂O calcination resulted in a significant decrease in the levels of nickel aluminate. The N₂O calcination also led to an enhancement in the amount of NiO as well as nickel ions present on the surface of the catalyst. Interestingly, compared to an air calcined catalyst, the N₂O calcined catalyst contained larger nickel particles after reduction but the N₂O calcined catalyst had a much larger nickel surface area and dispersion, which resulted in higher glycerol conversion and hydrogen yield.     

Effect of lithium carbonate on nickel catalysts for direct internal reforming MCFC

Despite many advantages of the direct internal reforming molten carbonate fuel cell (DIR-MCFC) in producing electricity, there are many problems to solve before practical use. The deactivation of reforming catalyst by alkali like lithium is one of the major obstacles to overcome. A promising method is addition of TiO₂ into the Ni/MgO reforming catalyst, which resulted in the increased resistance to lithium poisoning as we previously reported. To understand how added titania worked, it is necessary to elucidate the deactivation mechanism of the catalysts supported on metal oxides such as MgO and MgO–TiO₂ composite oxide.Several supported nickel catalysts deactivated by lithium carbonate were prepared, characterized and evaluated. The Ni/MgO catalyst turned out to be most vulnerable to lithium deactivation among the employed catalysts. The activity of the Ni/MgO gradually decreased to zero with increasing amount of lithium addition. Deactivation by lithium addition resulted from the decrease of active site due to sintering of nickel particles as well as the formation of the Li_yNi_xMg_1−x−yO ternary solid solution. These were evidenced by H₂ chemisorption, temperature programmed reduction, and XRD analyses. As an effort to minimize Li-poisoning, titanium was introduced to MgO support. This resulted in the formation of Ni/Mg₂TiO₄, which seemed to increase resistance against Li-poisoning.     

Hydrogen production from sorption enhanced steam reforming of ethanol using bifunctional Ni and Ca-based catalysts doped with Mg and Al

This work evaluated the performance of nickel-based catalysts supported on CaO and CaO–MgO–Al₂O₃ in the sorption enhanced steam reforming of ethanol (SESRE) aiming the production of high purity H₂. The catalysts were prepared by sol-gel method and characterized by different methods: Temperature programmed reduction (TPR), X-ray diffraction (XRD), Scanning Electron Microscopy (SEM) with chemical element mapping, N₂ physisorption and CO₂ capture capacity determined by thermogravimetric analysis (TGA). XRD analysis showed that the predominant phases were CaO, MgO, CaCO₃, Ca(OH)₂ and NiO in the calcined samples and Ni⁰ in the reduced and passivated samples. TPR profiles indicated that all catalysts presented a high degree of reduction (Ni/CaMgAl-68 > Ni/CaMgAl-79 > Ni/Ca), although Ni/CaMgAl-X samples presented high reduction temperatures indicating the formation of NiAl₂O₄. The addition of MgO and Al₂O₃ to CaO was very beneficial since the deactivation coefficients, calculated by the TGA data modeling, decreased by a factor of 3.8 for Ni/CaMgAl-79 and by a factor of 4.3 for Ni/CaMgAl-68 when compared to the Ni/Ca catalyst. The catalytic tests in the SESRE showed that Ni/CaMgAl-79 catalyst had the best performance since it had the longest high purity hydrogen production time. In the pre-breakthrough period, the H₂ mole fractions were close to 90% for all samples during all reaction cycles. After the reaction-regeneration cycles, the average crystallite size of CaO estimated by XRD increased around 38, 6 and 35% for Ni/Ca, Ni/CaMgAl-79 and Ni/CaMgAl-68, respectively. Thus, adding a dopant to the sorbent material proved to be an effective strategy to obtain a more stable catalyst capable to produce hydrogen of high purity.     

Optimization of CO2 reforming of methane process for the syngas production over Ni–Ce/TiO2–ZrO2 catalyst using the Taguchi method

In the present study, Taguchi method-based design of experiment with L9 orthogonal array was implemented to optimize the process conditions for CO₂ reforming of methane over the Ni–Ce/TiO₂–ZrO₂ catalyst. The catalyst composition, catalyst reduction temperature, reaction operating temperature, and the CO₂/CH₄ ratio of the reactant gas were the control parameters. The performance index was considered as the response of the Taguchi experiment. The performance index was calculated by considering the product gas H₂/CO ratio, deactivation factor, carbon deposition, and maximum CH₄ conversion. The catalysts were prepared in two steps using the evaporation-induced self-assembly and urea deposition-precipitation methods. The catalysts were characterized in their fresh and spent stages using various techniques like X-ray diffraction, N₂-physisorption, H₂ temperature-programmed reduction, inductively coupled plasma-mass spectroscopy, Scanning electron spectroscopy, Transmission electron spectroscopy, and Thermogravimetric analysis. The results showed that the operating temperature had the principal effect on the performance index. The optimal conditions from signal/noise ratio analysis were Cat3 catalyst with Ti/Zr ratio of 1:3, catalyst reduction temperature of 600 °C, the operating temperature of 800 °C, and feed gas ratio as CO₂/CH₄ = 2. Higher Zr content in the catalyst support and the lower reduction temperature favor enhancing the performance index.     

Pathways of ethanol steam reforming over ceria-supported catalysts

Ceria-supported Pt, Ir and Co catalysts are prepared herein by the deposition–precipitation method and investigated for their suitability in the steam reforming of ethanol (SRE) at a temperature range of 250–500 °C. SRE is tested in a fixed-bed reactor under an H₂O/EtOH molar ratio of 13 and 20,000 h⁻¹ GHSV. Possible pathways are proposed according to the assigned temperature window to understand the different catalysts attributed to specific reaction pathways. The Pt/CeO₂ catalyst shows the best carbon–carbon bond-breaking ability and the lowest complete ethanol conversion temperature of 300 °C. Acetone steam reforming over the Ir/CeO₂ catalyst at 400 °C promotes a hydrogen yield of up to 5.3. Lower reaction temperatures for the water–gas shift and acetone steam reforming are in evidence for the Co/CeO₂ catalyst, whereas the carbon deposition causes its deactivation at temperature over 500 °C.     

Carbon deposition on Ni/ZrO2–CeO2 catalyst during steam reforming of acetic acid

Steam reforming of acetic acid, one model compounds of bio-oil, was studied on the Ni/ZrO₂–CeO₂ catalysts which were prepared by the impregnation method. The results showed that high acetic acid conversion and hydrogen yield were obtained in the temperature range of 650–750 °C when H₂O/HAC ratio was 3. Nevertheless, the catalyst deactivation was caused by carbon deposition eventually with time-on-stream. In order to discuss the behavior of the carbon deposition on the Ni/ZrO₂–CeO₂ catalyst during steam reforming of bio-oil, the structure and morphology of carbon deposition were investigated by BET, XRD, TG/DTA, TPR, SEM and EDX techniques. All the experimental results showed acetone and CO were the important carbon precursors of acetic acid reforming and the graphitic-like carbon was the main type of carbon deposition on the surface of the deactivated 12%Ni/CeO₂–ZrO₂ catalyst.     

Hydrogen production from aqueous phase reforming of glycerol over attapulgite-supported nickel catalysts: Effect of acid/base treatment and Fe additive

In this paper, a series of nickel-based catalysts supported on modified attapulgite (ATP) by acid (citric acid and EDTA) and base (NaOH) were prepared and applied to the aqueous phase reforming of glycerol (APRG). The modified ATP (MA) and as-prepared catalysts were detected using N₂ adsorption-desorption, ICP-OES, XRD, FT-IR, SEM-EDS, HRTEM, XPS, H₂-TPR, NH₃-TPD. The results manifested that the acid/base treatment of ATP significantly increased the surface area and pore volume, enhanced the metal-support interaction (MSI) and decreased the Ni particle size, resulting in the better glycerol conversion and H₂ selectivity, especially for Ni/MA-E catalyst, where the ATP was pretreated using EDTA. In addition, the bimetallic NiFe/MA-E catalyst exhibited the highest conversion of glycerol to gas product (54.4%) and H₂ selectivity (84.6%) at very low temperature (280 °C). These results were attributed to the strongest the interplay of active metal with support by the formation of Ni–Fe alloy, resulting in the highest active metal dispersion, smallest metal particle size, lowest the reducibility of active metal and most surface Ni⁰ content. According to the characterizations of spent catalysts, it demonstrated that monometallic Ni catalysts presented obvious sintering of Ni metal particle and larger accumulation of carbon deposition, which led to the deactivation of the catalyst. While NiFe/MA-E catalyst showed less particle agglomeration and coke formation attributed to the lower content of surface acid site. Apart from that, another cause of catalyst deactivation might be the destruction of ATP skeleton during APRG.     

Catalytic reforming of gasoline to hydrogen: Kinetic investigation of deactivation processes

Catalytic reforming of gasoline to a hydrogen-rich gas is a possible route to feed a fuel cell for electricity production on-board a vehicle. To properly design a fuel processor system, knowledge about the kinetics of the different reactions involved in the reforming is needed. Kinetic studies are hampered by the fact that sulfur compounds present in commercial gasoline may lead to a progressive deactivation of the catalyst. We have undertaken such a study with an optically accessible catalytic channel flow reactor enabling concentration profiles and catalyst surface temperatures to be measured. The concentration profiles measured at different times on stream revealed a progressive deactivation of the catalyst. Isothermal reaction rate constants, depending on the time on stream, were derived by fitting a Langmuir–Hinshelwood kinetic model to the experimental species concentration profiles. The modeling results indicated that the steam reforming of higher hydrocarbons was more strongly affected by the presence of sulfur in the feed than the water gas shift reaction and the steam reforming of methane. Carbon formation was inferred from changes in surface emissivity during the experiments. It is suggested that the primary reason for the observed deactivation is due to the presence of sulfur compounds in the feed. The deactivated catalyst would then promote the formation of coke at the surface, i.e. coke formation is probably a consequence of the deactivation and not a cause for it. Although the variability in preparing the coated catalytic plates affected the measured kinetic rate parameters, the observed trends were in general consistent for all runs.