Catalytic Partial Oxidation Of CH4 Research Articles

Catalytic conversion of high-GWP gases N2O and CH4 to syngas (H2 + CO) on SiO2@Ni-Cr layered nano-oxide-coated monolithic catalyst.

Layered double hydroxides (LDHs) are 2D nano-sheets where different M2+ and M3+ metal cations are uniformly distributed in Mg(OH)2 brucite-like sheets and various charge-compensating anions (An-) are present in their interlayer spaces. This work includes preparation of different SiO2@Ni/Cr mixed-metal layered nano-oxide-type catalysts by the calcination of SiO2@Ni-Cr LDH nano-composite-based alcogel coated over a honeycomb monolithic substrate and their use as a catalytic device for the study of catalytic partial oxidation (CPO) of CH4 both in the presence of O2 and in the presence of N2O under atmospheric pressure at different temperatures not exceeding 500°C to study the effect of N2O on the CPO of CH4. It was observed that in the presence of O2 the yield of syngas (H2 + CO) did not exceed 90% whereas in the presence of N2O about 99.9% syngas (H2 + CO) was observed. The selectivity towards syngas production reached a maximum value when an optimal reaction condition was maintained at 1:1 CH4:N2O mol ratio with a temperature of 500°C. XPS analysis showed that a NiO-type compound formed on the decomposition of the LDH component after H2 treatment was reduced to disperse Ni0, which acted as an active catalytic species. Graphical abstract Schematic representation of catalytic partial oxidation of CH4 in the presence of N2O by SiO2@Ni-Cr-LDH-based mixed-metal nano-oxide.

Electrodeposition of Rh/Mg/Al hydroxides with different Mg-contents on metallic foams as catalyst precursors

This work investigated the electrodeposition of Rh/Mg/Al mixed hydroxides with different Mg-contents on open-cell foams through the electro-base generation method using nitrate electrolytes. The influence of Mg2+ on both the electrodeposition process and properties of the coating (after electrodeposition, calcination, and catalytic partial oxidation (CPO) of CH4 tests) was studied. The nature of cations being precipitated (Mg2+ or Al3+) influenced significantly the production of OH– through reduction of nitrate and water, which in turn determined the quality of the coating in terms of composition and adhesion. In reference samples, an absence of either Mg2+ (Rh5Al95) or Al3+ (Rh5Mg95) declined the coating quality, namely, more cracks developed due to the prominent reduction of H2O (in case of Rh5Al95) or reduction of Rh3+ to Rh0 occurred (Rh5Mg95 ). On the other hand, the presence of both Mg2+ and Al3+ in Rh/Mg/Al hydrotalcite-type (HT) samples improved significantly the coating loading and its adhesion, even after thermal treatment at 900 °C, as well as the dispersion of Rh in the reduced catalyst. Moreover, increasing the amount of Mg2+ to a given Mg/Al ratio at which a pure Rh/Mg/Al HT precursor was formed (e.g. Rh5Mg70Al25) resulted in significant increment of Rh dispersion compared to those with lower Mg content (i.e. Rh5Mg50Al45). Such modifications on the properties of the coating (loading, adhesion, and Rh dispersion) subsequently influenced the performance in the CPO of CH4. Finally, temperature profiles along the catalytic bed were reported in correlation with CH4 conversion and syngas selectivity.

Insights into coated NiCrAl open-cell foams for the catalytic partial oxidation of CH4

NiCrAl foams coated by a catalytic layer are stable under reaction conditions and decrease the hot spots, making them an alternative to FeCrAl materials.

Catalytic partial oxidation of CH4 to syn gas (H2/CO) in presence of N2O over periclase type SiO2@Ni(Mg,Al)O catalyst synthesized by non aqueous route

Periclase type Ni/Mg/Al mixed-metal oxide prepared from sol-gel derived SiO2@Ni-Mg-Al Layered Double Hydroxides (LDH) nanocomposite at SiO2:LDH ratios 0:1 and 1:1 was used as a catalyst for catalytic partial oxidation (CPO) of CH4 in presence of N2O as well as oxygen. The catalysts were characterized by XRD, BET surface area, H2-TPR and XPS analysis. The presence of SiO2 dispersant influenced the catalytic property. The nascent oxygen formed by the decomposition of N2O does not re-oxidize Ni0 like molecular oxygen which act as the active species and leads to partial oxidation of CH4. SiO2@Ni-Mg-Al (1:1) catalyst showed about 99.99% H2 and 99.8% CO yield between the temperature range of 200-500 °C.

Bimodal mesoporous NiO/CeO2-δ-YSZ with enhanced carbon tolerance in catalytic partial oxidation of methane—Potential IT-SOFCs anode

In the present study we report on the activity, selectivity and stability of the bimodal mesoporous NiO/CeO2-δ-YSZ anodes for IT-SOFCs applications. These materials present high concentration of Ce3+ ions stably retained in the lattice, which proved to be efficient for the catalytic partial oxidation of CH4 to syngas in the temperature range 600–800 °C. The excellent carbon tolerance was proved by a comprehensive XPS analysis, which monitored the amount of carbon before and after catalytic partial oxidation of methane (CPOM) tests. The mesoporous anodes templated by hexadecyltrimethylammonium bromide (CTAB) and tripropylamine (TPA) were obtained using a hydrothermal synthesis route. The effect of Ni and Ce incorporation on the yttria stabilized zirconia (YSZ) structure, texture, morphology and surface chemistry was discussed and correlated with catalytic and electrochemical behavior. The exhaustive characterization of the bulk and surface properties of the catalysts have been accomplished by means of complementary methods: XRD, SEM / EDX / HRTEM, TGA / TPR, XPS. The electrochemical and catalytic performance were improved when the surface contains more reduced ceria and NiO was formed as secondary phase. These features lead to a large number of vacancies and consequently a better oxygen migration, which facilitate the carbon removal.

Hydrotalcite-Type Materials Electrodeposited on Open-Cell Metallic Foams as Structured Catalysts

Structured catalysts based on hydrotalcite-derived coatings on open-cell metallic foams combine tailored basic/acidic sites, relatively high specific surface area and/or metal dispersion of the coating as well as low pressure drop and enhanced heat and mass transfer of the 3D metallic support. The properties of the resulting structured catalysts depend on the coating procedure. We have proposed the electro-base generation method for in situ and fast precipitation of Ni/Al and Rh/Mg/Al hydrotalcite-type materials on FeCrAlloy foams, which after calcination at high temperature give rise to structured catalysts for syngas (CO + H2) production through Steam Reforming and Catalytic Partial Oxidation of CH4. The fundamental understanding of the electrochemical-chemical reactions relevant for the electrodeposition and the influence of electrosynthesis parameters on the properties of the as-deposited coatings as well the resulting structured catalysts and, hence, on their catalytic performance, were summarized.

Coprecipitated-like hydrotalcite-derived coatings on open-cell metallic foams by electrodeposition: Rh nanoparticles on oxide layers stable under harsh reaction conditions

Structured catalysts based on open-cell metallic foams coated by a catalytic film offer a great potential for intensification and optimization of catalytic processes. Here, we demonstrated the feasibility of the electrodeposition to synthesize in situ and quick Rh/Mg/Al hydrotalcite-type (HT) syngas catalyst precursors with controlled composition, morphology and thickness around 5 to 20 μm on the surface of FeCrAlloy foams using a two-compartment flow electrochemical cell. After calcination at 900 °C, catalytic coatings with properties similar to those of conventional co-precipitated HT-derived catalysts were identified by synchrotron nano-XRF/XRD tomography and HRTEM. The resulting structured catalysts, therefore, merged the properties of both HT-derived catalysts and open-cell foams, namely, thermally stable nano MgO- and spinel-type phases where Rh was dispersed and stabilized against sintering, and high mass and heat transfer. Moreover, the development of a MgAl2O4 thin film in the support-coating interface, by chemical reaction between Mg2+ from the coating and Al3+ from the support during calcination, increased the catalyst adhesion. Consequently, active and stable performance was obtained under harsh reaction conditions in the catalytic partial oxidation of CH4 to syngas as a model reaction. Even in the catalysts operating under severe reaction conditions for about 50 h, the coating was stable and Rh metallic nanoparticles around 2 nm were still well dispersed.

Stable Rh particles in hydrotalcite-derived catalysts coated on FeCrAlloy foams by electrosynthesis

Rh-based structured catalysts for the Catalytic Partial Oxidation of CH4 to syngas were prepared by electrosynthesis of Rh/Mg/Al hydrotalcite-type compounds on FeCrAlloy foams and calcination. The effects of Rh content, total metal concentration, and partial replacement of Mg2+ by Ni2+ in the electrolytic solution on coating thickness, Rh speciation, metallic particle size, and catalytic activity were investigated by SEM/EDS, μ-XRF/XANES and tests under diluted and concentrated reaction conditions.The amount of Rh species, present as Mg (RhxAl1−x)2O4, depended on the thickness of the electrosynthesised layer as well as the Rh particle size and dispersion. Smaller and more dispersed particles were obtained by decreasing the Rh concentration in the electrolytic solution from Rh/Mg/Al=11/70/19 to 5/70/25 and 2/70/28 atomic ratio% (a.r.%) and in thinner rather than thicker layers. Despite the improvement in metallic particles features, the CH4 conversion was negatively affected by the low amount of active sites in the coating, the high metal support interaction and possibly the oxidation of metallic particles and carbon formation.A larger amount of solid containing well dispersed Rh particles was deposited by increasing the total metal concentration from 0.03M to 0.06M with the Rh/Mg/Al=5/70/25 a.r.%, and the catalytic performances were enhanced. The partial replacement of Mg2+ by Ni2+ gave rise to a very active bimetallic Rh/Ni catalyst, CH4 conversion and selectivity to syngas were above 90%, however, it slightly deactivated with time-on-stream.

Improvement in the coating homogeneity in electrosynthesized Rh structured catalysts for the partial oxidation of methane

The precipitation of Rh/Mg/Al and Rh/Al hydroxides on the surface of FeCrAlloy foams by a base electrogeneration method was investigated to improve the properties of the deposited film (homogeneity and composition) and therefore the performances of the structured catalysts, obtained by calcination, in the Catalytic Partial Oxidation of CH4 to syngas. The work focussed on decreasing current gradients within open-cell foam cylinders by increasing the number of electrical contacts from 1 to 3 points to promote a more homogeneous precipitation of the hydroxides. Electrochemical and catalytic tests as well as SEM/EDS and μ-XRF/XRD analyses allowed to correlate the effect of the number of electrical contact points with materials properties. Lastly, syntheses were performed on Pt plates to study the effect of the electrical behaviour and shape of the support on the composition of the film.A more homogeneous coating of the foam surface was achieved by adopting a configuration with 3 contact points since the reduction of nitrates and water molecules that generates the basic media in the vicinity of the support was enhanced. Layer thicknesses up to 5–15μm were deposited; however, the sequential precipitation of a film with composition closer to the expected one and a layer enriched in Al and Rh (outer layer) was not avoided. The improvement in the coating gave rise to enhanced performances for a sample prepared at −1.1V for 3000s. Contrarily, the low adherence of the outer layer in a sample prepared at −1.2V for 2000s during both calcination and catalytic tests may be responsible of the unexpected decrease in catalytic performances. The same sequential precipitation was observed by performing the syntheses on Pt plates, showing that the electrical nature the support did not play a key role on this phenomenon.

Role of Coating-Metallic Support Interaction in the Properties of Electrosynthesized Rh-Based Structured Catalysts

Rh-structured catalysts for the catalytic partial oxidation of CH4 to syngas were prepared by electrosynthesis of Rh-containing hydrotalcite-type (HT) compounds on FeCrAlloy foams followed by calcination at 900 °C. During the calcination the simultaneous decomposition of the layered HT structure and formation of the protective FeCrAlloy outer shell in alumina occurred. Here, we studied the role of the coating-metallic support interaction in the properties of the catalysts after calcination, H2 reduction, and catalytic tests, by a combination of electron (FEG-SEM/EDS) and synchrotron X-ray (XRF/XRPD and XRF/XANES) microscopic techniques. The characterization of crystalline phases in the metallic support and coating and distribution of Rh active species was carried out on several samples prepared by modifying the Rh content in the electrolytic solution (Rh/Mg/Al = 11.0/70.0/19.0, 5.0/70.0/25.0, 0/70.0/30.0 atomic ratio). A sample was also prepared with no aluminum in the electrolytic solution (Rh/Mg/Al = 13...

Role of the composition and preparation method in the activity of hydrotalcite-derived Ru catalysts in the catalytic partial oxidation of methane

Hydrotalcite-derived Ru catalysts were tested in the catalytic partial oxidation of CH4 to produce syngas. The effect of Ru content, oxidic matrix composition, and preparation procedure on chemical–physical properties and performances of catalysts was studied. Bulk catalysts (0.25 and 0.50 wt.% Ru) were obtained via Ru/Mg/Al hydrotalcite-type (HT) precursors with carbonates or silicates as interlayer anions. A supported catalyst was prepared by impregnation on a calcined Mg/Al–CO3 HT. Ru/γ-Al2O3 was evaluated for comparison. Both the Ru dispersion and the interaction with the support decreased as the Ru loading increased and when silicates were present due to RuO2 segregation. Regardless of the Ru loading, carbonate-derived catalysts performed better than those containing silicates. The increased Ru loading improved the initial activity, but deactivation occurred after high temperature tests. Stability tests for shorter contact times over a 0.25 wt.% bulk sample obtained from Ru/Mg/Al HT with carbonates showed a tendency to deactivate at 750 °C.

Effect of pressure in the autothermal catalytic partial oxidation of CH4 and C3H8: Spatially resolved temperature and composition profiles

Operation under pressure is a major requirement for the intensification of the catalytic partial oxidation (CPO) of light hydrocarbons. Related issues are the increase of the thermal loads experienced by the catalyst and the promotion of gas phase chemistry, which can lead to the formation of coke precursors. In this work, we analyze the autothermal CPO of C3H8 and CH4, carried out between 1 and 4bar at constant mass flow rate over a Rh-coated honeycomb catalyst. Spatially resolved temperature and concentration profiles are presented and analyzed with a mathematical model of the reactor, which includes appropriate mass and heat transfer correlations and detailed kinetic schemes for the homogeneous and the heterogeneous chemistry. The results show that pressure affects the heterogeneous process thermodynamically but not kinetically. In fact, in the final part of the catalyst, where the reaction approaches the equilibrium, higher pressures cause an increase of the outlet temperatures and a decrease of the selectivity to syngas. In the first part of the catalyst, where the progress of the reaction is controlled by kinetics, pressure has no effect on both temperature and concentration profiles due to the dominant role of mass transfer on the consumption of O2 and fuel. In the case of CH4 CPO, there is no evidence of homogenous reactions, whereas, in C3H8 CPO pressure promotes gas phase cracking, which leads to the formation of methane and intermediate C2+ species. Experiments performed on a thin catalyst slice confirm that heterogeneous steam reforming reactions have a key role in cleaning the gas phase from these C2+ species, preventing the catalyst from coking.

Critical evaluation of in situ probe techniques for catalytic honeycomb monoliths

Collecting spatially resolved gas-phase concentration profiles in catalytic monoliths by applying suction probe techniques has become an important tool for understanding the reaction sequence and for optimizing the design of structured catalysts. Here, the significance of the probing technique’s impact on the measured data is investigated by means of CFD simulations and experimental investigation of catalytic partial oxidation of CH4 on a Rh-coated honeycomb catalyst. Different positions of a suction probe (diameter=170μm) inside a rectangular channel (height=795μm) of a monolith are compared with respect to the influence on flow field, residence time, and reaction progress. The influence of the probe on the measured data is shown to strongly depend on its position. The maximum error can be over 50% with respect to the residence time. For an isothermal process, the error in the concentration profiles can be corrected by using a function which is only dependent on the geometrical structure of the monolith. However, for a process with a temperature gradient along the catalytic channel, such as CPOX of methane, the correction function is not applicable. An appropriate comparison of experiments and simulations requires a three-dimensional CFD simulation taking the probe into account.

Coating of FeCrAlloy foam with Rh catalysts: Optimization of electrosynthesis parameters and catalyst composition

Coating of FeCrAlloy foam cylinders with Rh-based catalysts was performed by the in situ electrosynthesis of Rh/Mg/Al hydrotalcite-type precursors on the surface of the support. The structured catalysts, obtained after calcination at 900°C, were characterized and tested in the catalytic partial oxidation of CH4 at an oven temperature of 750°C, by feeding diluted and concentrated CH4/O2/He gas mixtures. Electrochemical parameters (potential applied, synthesis time and supporting electrolyte) and the composition of the catalyst precursor (Rh/Mg/Al atomic ratio) were changed with the aim to optimize both the properties of the coating and catalytic performances. The sample prepared in absence of KNO3 as the supporting electrolyte at −1.2V vs saturated calomel electrode for 2000s yielded the catalyst with the best performances thanks to an improved coating and large amount of Rh in the outer part of the catalytic coating.

Selectivity of chemisorbed oxygen in C–H bond activation and CO oxidation and kinetic consequences for CH 4–O 2 catalysis on Pt and Rh clusters

Rate measurements, density functional theory (DFT) within the framework of transition state theory, and ensemble-averaging methods are used to probe oxygen selectivities, defined as the reaction probability ratios for O * reactions with CO and CH 4, during CH 4–O 2 catalysis on Pt and Rh clusters. CO 2 and H 2O are the predominant products, but small amounts of CO form as chemisorbed oxygen atoms (O *) are depleted from cluster surfaces. Oxygen selectivities, measured using 12CO– 13CH 4–O 2 reactants, increase with O 2/CO ratio and O * coverage and are much larger than unity at all conditions on Pt clusters. These results suggest that O * reacts much faster with CO than with CH 4, causing any CO that forms and desorbs from metal cluster surfaces to react along the reactor bed with other O * to produce CO 2 at any residence time required for detectable extents of CH 4 conversion. O * selectivities were also calculated by averaging DFT-derived activation barriers for CO and CH 4 oxidation reactions over all distinct surface sites on cubo-octahedral Pt clusters (1.8 nm diameter, 201 Pt atoms) at low O * coverages, which are prevalent at low O 2 pressures during catalysis. CO oxidation involves non-activated molecular CO adsorption as the kinetically relevant step on exposed Pt atoms vicinal of chemisorbed O * atoms (on *–O * site pairs). CH 4 oxidation occurs via kinetically relevant C–H bond activation on *– * site pairs involving oxidative insertion of a Pt atom into one of the C–H bonds in CH 4, forming a three-centered HC 3–Pt–H transition state. C–H bond activation barriers reflect the strength of Pt–CH 3 and Pt–H interactions at the transition state, which correlates, in turn, with the Pt coordination and with CH 3 * binding energies. Ensemble-averaged O * selectivities increase linearly with O 2/CO ratios, which define the O * coverages, via a proportionality constant. The proportionality constant is given by the ratio of rate constants for O 2 dissociation and C–H bond activation elementary steps; the values for this constant are much larger than unity and are higher on larger Pt clusters (1.8–33 nm) at all temperatures (573–1273 K) relevant for CH 4–O 2 reactions. The barriers for the kinetically relevant C–H bond dissociation step increase, while those for CO oxidation remain unchanged as the Pt coordination number and cluster size increase, and lead, in turn, to higher O * selectivities on larger Pt clusters. Oxygen selectivities were much larger on Rh than Pt, because the limiting reactants for CO oxidation were completely consumed in 12CO– 13CH 4–O 2 mixtures, consistent with lower CO/CO 2 ratios measured by varying the residence time and O 2/CH 4 ratio independently in CH 4–O 2 reactions. These mechanistic assessments and theoretical treatments for O * selectivity provide rigorous evidence of low intrinsic limits of the maximum CO yields, thus confirming that direct catalytic partial oxidation of CH 4 to CO (and H 2) does not occur at the molecular scale on Pt and Rh clusters. CO (and H 2) are predominantly formed upon complete O 2 depletion from the sequential reforming steps.

Catalytic partial oxidation of CH 4 with nickel–lanthanum-based catalysts

The aim of this work, concerning with the partial oxidation of methane to syngas in a self-sustained short contact time reactor using pure oxygen as oxidant, was the development of perovskite-based nickel–lanthanum (LaNiO 3 with Ni partially substituted by Co and Pt) catalysts and the comparison of their performance with that of 5% nickel on alumina catalyst. The prepared catalytic materials were arranged in a fixed bed and the activity tests were carried out by increasing the WHSV from ∼130 to ∼560 N l h −1 g cat −1. Perovskite-based catalysts were characterized by performances lower than that of 5% Ni/Al 2O 3. The very low perovskites catalytic performance towards the partial oxidation of methane was mainly due to the high reducibility of their structures into La 2O 3, metallic Ni, and Ni oxides; moreover, La and Ni species further reacted with the CPO reaction products CO 2 and H 2O leading thus to the formation of the poorly active species La(OH) 3, La 2NiO 4 and La 2O 2CO 3. On the contrary, 5% Ni/Al 2O 3 catalyst showed a very satisfactory CH 4 conversion always above 85%, remaining stable by varying WHSV. The same trend was noticed for H 2 and CO selectivity, both around 90%. Furthermore, as concerns the bed temperature by increasing WHSV, 5% Ni/Al 2O 3 catalyst presented quite stable T in and T out (the latter around 1200–1250 °C), whereas the perovskite-based catalysts showed a quick T in decrease and T out increase, anyway not exceeding 1200 °C. The good performance and high thermal stability of 5% Ni/Al 2O 3 catalyst was probably related to the arrangement of the nickel particles, which resulted somehow thermally protected as partially embedded in the alumina carrier.

Surface temperature profiles in CH 4 CPO over honeycomb supported Rh catalyst probed with in situ optical pyrometer

The rigorous estimation of the temperature of the surface of a working catalyst is an issue of fundamental and practical relevance, especially in the case of high temperature reactions. In the present article, the potentialities and complexities of an optical technique, consisting of an optical fiber connected to an infrared pyrometer, are explored with respect to the catalytic partial oxidation of CH 4 performed over Rh honeycomb catalysts. The case of a 400 cpsi cordierite honeycomb support is analyzed. The effects of different geometrical configurations of the fiber probe are measured and the associated optical artifacts are analyzed. By comparing the experimental results with a predictive numerical model, it is confirmed that the expected surface temperatures are closely captured with a 45° angled optical fiber specifically calibrated and that the use of a thermocouple, sliding from the front face, reveals the temperature of the gas phase. This latter can be dramatically different from that of the solid phase at the reactor inlet, where heat and mass transfer control the kinetics. The application of a non contact infrared device to measure the solid surface temperature is therefore essential, provided that its application is minimally intrusive both with respect of the catalytic volume and of the reactor set-up.

Catalytic partial oxidation of CH 4 over Ni-substituted barium hexaaluminate catalysts

Ba 0.75Ni y Al 12− y O 19− δ ( y = 0.2, 0.4, 0.6, 0.8 and 1.0) catalysts were tested for the partial oxidation of CH 4 at temperatures between 200 and 900 °C. Temperature programmed reaction results indicate that light-off for the partial oxidation reaction occurred between 665 and 687 °C for all catalysts. Isothermal runs performed at 900 °C on the catalysts showed stable reaction product concentrations, consistent with equilibrium. Post-reaction analysis of the used catalysts showed that there are two distinct zones in the catalyst bed. In a short leading edge of the bed, the apparently complete consumption of oxygen leads to a catalyst which XANES analysis shows is primarily Ni-substituted into the hexaaluminate phase. In the downstream portion of the bed, Ni is shown to be present as metallic Ni. This corresponds to a reaction sequence in which the oxidation of CH 4 proceeds at the inlet until all oxygen is reacted, followed by the reaction of CO 2 and H 2O with unreacted CH 4, and its derivatives, to produce the final syngas mixture. From the change in the unit-cell dimensions with Ni substitution, there is a clear indication that Ni 2+, which has a larger ionic radius than aluminum, substitutes for Al 3+ in the hexaaluminate lattice in the synthesis process, and there is no restructuring of the bulk hexaaluminate phase after the Ni is removed from the lattice.

Dominant Reaction Pathways in the Catalytic Partial Oxidation of CH4 on Rh

Reforming technologies are at the heart of converting fossil fuels and biofuels to syngas and hydrogen for novel energy applications and, among reforming technologies, catalytic partial oxidation is appealing for decentralized energy production due to the compactness of reactors. Yet, the mechanisms of these reactions are poorly understood. Here we combine fundamental surface chemistry and detailed reactor models to elucidate the pathways leading to syngas and propose strategies for optimizing the process.

Chemical and geometric effects of Ce and washcoat addition on catalytic partial oxidation of CH 4 on Rh probed by spatially resolved measurements

Using a spatially resolved sampling technique, the catalytic partial oxidation of CH 4 to synthesis gas was investigated over 80 ppi α-Al 2O 3 foams coated with three catalytic formulations: 5 wt% Rh, 5 wt% Rh/2 wt% γ-Al 2O 3 washcoat and 5 wt% Rh–2 wt% Ce/2 wt% γ-Al 2O 3 washcoat. Experiments were performed at atmospheric pressure and ∼8 millisecond contact time, with 20% v/v CH 4 and C/O ratio equal to 1. Data show that the length of the oxidative zone (∼2 mm) is unaffected by the composition of the catalyst. The addition of γ-Al 2O 3 washcoat to Rh coated monoliths allows the reaction to reach adiabatic equilibrium by increasing the rates of steam reforming and water gas shift. Additionally, both the maximum and the gradients in the temperature profiles decrease significantly with the addition of washcoat. Data collected on Rh–Ce/washcoat show that the adiabatic equilibrium composition is reached through a different kinetic route: the consumption of CH 4 becomes slower, the production of CO 2 exhibits a maximum, and the production of H 2O is drastically moderated, suggesting that Ce has an active role in the CPO reaction kinetics. The features presented could be detected exclusively with spatially resolved measurements.