Rh based catalysts for indirect internal reforming ethanol applications in molten carbonate fuel cells

The feasibility of coupling a processor for internal indirect reforming of ethanol/water with molten carbonate fuel cells has been verified by several experiments. Two different Rh/Al₂O₃ catalysts have been prepared and characterised. Several tests to measure the catalytic activity on ethanol steam reforming process have been performed both on alumina and supported catalysts. The tests evidenced that ethanol can be decomposed and steam reforming process can be obtained at well determined conditions of temperature and catalyst load. The 5% Rh/Al₂O₃ catalyst produced, at 923 K, hydrogen rich gas mixture, that can be considered of high interest for molten carbonate fuel cell applications because it is free from any production of ethylene or other undesirable products. Further, this interest has been confirmed by the good results obtained in the long-term tests carried out on the 5% Rh/Al₂O₃ catalyst.     

A comparative study of catalytic behaviors of Mn,Fe, Co,Ni, Cu and Zn–Based catalysts in steam reforming of methanol,acetic acid and acetone

This study investigated the distinct catalytic behaviors of mono Mn, Fe, Co, Ni, Cu and Zn catalysts in the reforming of the small organics including methanol, acetic acid and acetone. The results showed that Mn, Fe or Zn-based catalysts showed almost no activity for steam reforming of either methanol, acetic acid or acetone, due to their low capacity to break the chemical bonds of the organics or to activate steam. Co and Cu-based catalysts were generally active for steam reforming of methanol. Nevertheless, Co-based catalysts promoted methanol decomposition to form a substantial amount of CO. Alumina as a support remarkably influenced catalytic stability of the catalyst. The unsupported Cu catalyst showed a much lower stability than Cu/Al₂O₃. Nevertheless, the unsupported Ni was more stable than Ni/Al₂O₃ catalyst, due to its high resistivity towards coking. The unsupported Co, however, was prone to coking. The C/H ratios in the coke formed over the unsupported and alumina-supported Ni or Co catalysts were distinct, indicating the involvement of alumina in the coking process. In addition, Ni and Co catalysts behaved differently. Ni/Al₂O₃ showed a superior stability than Co/Al₂O₃ in steam reforming of acetone. The coke formed on Ni/Al₂O₃ was more aromatic than that over Co/Al₂O₃ catalysts while morphologies of coke (nanotubes over Ni/Al₂O₃ versus fibrous coke over Co/Al₂O₃) were also different.     

Ni/MgO–Al2O3 and Ni–Mg–O catalyzed SiC foam absorbers for high temperature solar reforming of methane

Ni catalyst supported on MgO–Al₂O₃ (Ni/MgO–Al₂O₃) prepared from hydrotalcite, and Ni–Mg–O catalyst are studied in regard to their activity in the CO₂ reforming of methane at high temperatures in order to develop a catalytically activated foam receiver–absorber for use in solar reforming. First, the activity of their powder catalysts is examined. Ni/MgO–Al₂O₃ powder catalyst exhibits a remarkable degree of high activity and thermal stability as compared with Ni–Mg–O powder catalyst. Secondly, a new type of catalytically activated ceramic foam absorber – Ni/MgO–Al₂O₃/SiC – and Ni–Mg–O catalyzed SiC foam absorber are prepared and their activity is evaluated using a laboratory-scale receiver–reactor with a transparent quartz window and a sun-simulator. The present Ni-based catalytic absorbers are more cost effective than conventional Rh/γ-Al₂O₃ catalyzed alumina and SiC foam absorbers and the alternative Ru/γ-Al₂O₃ catalyzed SiC foam absorbers. Ni/MgO–Al₂O₃ catalyzed SiC foam absorber, in particular, exhibits superior reforming performance that provides results comparable to that of Rh/γ-Al₂O₃ catalyzed alumina foam absorber under a high flux condition or at high temperatures above 1000 °C. Ni/MgO–Al₂O₃ catalyzed SiC foam absorber will be desirable for use in solar receiver–reactor systems to convert concentrated high solar fluxes to chemical fuels via endothermic natural-gas reforming at high temperatures.     

Mo-promoted Ni/Al2O3 catalyst for dry reforming of methane

Mo-promoted alumina supported Ni catalysts were prepared through a conventional impregnation method and tested in dry reforming of methane (DRM) at temperatures from 550 to 850 °C. The catalysts were characterized by means of H₂-temperature programmed reduction (H₂-TPR), CO₂-temperature programmed desorption (CO₂-TPD), X-ray diffraction (XRD), N₂ physisorption and Raman spectroscopy. Mo-promotion caused a reduction in the DRM catalytic activity. The weaker interaction between NiO species and the alumina support, the formation of a MoNi₄ phase, and the lower basicity of this Ni-Mo/Al₂O₃ catalyst were identified as the main causes for its lower activity. However, pre-reducing the Ni-Mo/Al₂O₃ catalyst at temperatures lower than 700 °C, instead of 900 °C, resulted in a considerable increase of its catalytic activity. This was mainly due to the formation of a separate Ni⁰ phase that did not interact with Mo and to an increase in medium strength basicity.     

Metal foam-supported Pd–Rh catalyst for steam methane reforming and its application to SOFC fuel processing

Pd–Rh/metal foam catalyst was studied for steam methane reforming and application to SOFC fuel processing. Performance of 0.068 wt% Pd–Rh/metal foam catalyst was compared with 13 wt% Ni/Al₂O₃ and 8 wt% Ru/Al₂O₃ catalysts in a tubular reactor. At 1023 K with GHSV 2000 h⁻¹ and S/C ratio 2.5, CH₄ conversion and H₂ yield were 96.7% and 3.16 mol per mole of CH₄ input for Pd–Rh/metal foam, better than the alumina-supported catalysts. In 200 h stability test, Pd–Rh/metal foam catalyst exhibited steady activity. Pd–Rh/metal foam catalyst performed efficiently in a heat exchanger platform reactor to be used as prototype SOFC fuel processor: at 983 K with GHSV 1200 h⁻¹ and S/C ratio 2.5, CH₄ conversion was nearly the same as that in the tubular reactor, except for more H₂ and CO₂ yields. Used Pd–Rh/metal foam catalyst was characterized by SEM, TEM, BET and CO chemisorption measurements, which provided evidence for thermal stability of the catalyst.     

Autothermal reforming of ethanol on noble metal catalysts

Autothermal reforming of ethanol on zirconia-supported Rh and Pt mono- and bimetallic catalysts (0.5 wt-% total metal loading) was studied as a source of H₂-rich gas for fuel cells. The results were compared with those obtained on a commercial steam reforming catalyst (15 wt-% NiO/Al₂O₃). The Rh-containing catalysts exhibited the highest selectivity for H₂ production and were stable in 24 h experiments. The formation of carbonaceous deposits was lower on the noble metal catalysts than on the commercial NiO/Al₂O₃ catalyst. Thus, the Rh-containing catalysts are more suitable than the commercial NiO/Al₂O₃ catalysts for the ATR of ethanol.     

Solvent-free synthesis of Rh/meso-Al2O3 via mechanochemistry for hydrolytic dehydrogenation of ammonia borane

An effective strategy synthesis of Rh/meso-Al₂O₃ catalysts was demonstrated by mechanochemistry for hydrolytic dehydrogenation of ammonia borane (AB). These catalysts are characterized systematically by N₂ adsorption-desorption isotherms, X-ray diffraction (XRD), X-ray photoelectron spectrometry (XPS), scanning electron microscope (SEM), and transmission electron microscope (TEM). The results show that the turnover frequency (TOF) and activation energy (E_a) are 246.8 mol_H2·mol_Rh^?1·min^?1 and 47.9 kJ mol^?1 for hydrolytic dehydrogenation of at 298 K catalyzed by Rh/Al₂O₃-CTAB-400, obviously higher than those previously reported catalysts. Furthermore, catalyst Rh/Al₂O₃-CTAB-400 can be recycled by simple centrifugal separation and the catalytic activity is still well maintained after five cycles. In addition, a plausible mechanism for hydrolytic dehydrogenation of AB has also been proposed. This mechanochemical synthesis method exhibits great application prospects for the preparation of heterogeneous catalysts.     

Improved catalytic stability and anti-coking ability of Ni/La2O3–Al2O3 catalyst by doping alkaline earth metals for n-decane reforming

In this paper, a series of alkaline earth metals oxides doped Ni/La₂O₃–Al₂O₃ catalysts were synthesized by the coprecipitation method combined with two step impregnation methods. n-decane reforming was used to investigate these catalysts, in order to develop an excellent catalyst with better hydrogen selectivity, activity, stability, as well as lower carbon deposition. Deactivation by carbon deposition, the catalyst regenerability and stability tests were also used to weigh the selected catalyst. These catalysts are characterized by N₂ adsorption-desorption, XRD, NH₃-TPD, Raman, and TEM. The introduction of alkaline earth metals modifiers enhances the activity, stability and anti-coking ability, meanwhile the SrO modified Ni/La₂O₃–Al₂O₃ shows the best catalytic activity. Moreover, the hydrogen selectivity and conversion over regenerative Ni/La₂O₃–Al₂O₃/SrO catalysts were quite close to the results of fresh ones. The enhancements of M oxides doped catalysts (especially Sr) can be due to the improved textural properties, basicity, metal-support interaction and anti-coking ability. As a consequence, loading different metals in different ways helps to gradually improve the stability, activity and coking inhibition of catalysts is an effective approach to obtain a multi-function catalyst.     

Autothermal syngas production from model gasoline over Ni,Rh and Ni–Rh/Al2O3 monolithic catalysts

On-board reforming of liquid fuels is attractive for fuel cell-powered auxiliary power units in vehicles. In this work, monometallic Ni/Al₂O₃/cordierite, Rh/Al₂O₃/cordierite and bimetallic Ni–Rh/Al₂O₃/cordierite monolithic catalysts were prepared, characterized and tested in ATR of isooctane for syngas production. Compared to monometallic formulations, the bimetallic Ni–Rh/Al₂O₃ catalyst was active for ATR at lower temperature and H₂ production already reached the equilibrium composition in 400–550 °C temperature range. The Ni–Rh/Al₂O₃ catalyst exhibited stable performances for 140 h in ATR of isooctane at 700 °C, and was unaffected by oxidizing conditions at 700 °C. Thermoneutral reactions conditions at H₂O/C = 2 were obtained with O/C = 0.66. Carbon deposition was marginal during ATR of isooctane and no carbons whiskers were detected. Post-reaction characterizations showed that the Ni particles were small enough to prevent filamentous carbon formation, while Rh also prevented carbon film deposition by improving the gasification of adsorbed C with steam.     

Nickel based monometallic and bimetallic catalysts for synthetic and real bio-oil steam reforming

Catalysts based on Ni supported on alumina were studied for steam reforming (SR) of a synthetic bio-oil/bio-glycerol mixture and a real bio-oil. Catalyst tests were carried out in a continuous fixed bed reactor at atmospheric pressure and steam to carbon (S/C) ratio of 5.0. In the case of experiments with the bio-oil/bio-glycerol mixture the initial temperature was 1073 K, then it was successively changed to 973 K and 1073 K again to assess catalyst deactivation. Experiments with the bio-oil sample were run at 1073 K. First, the effect of modifications to the alumina support with CeO₂ and La₂O₃ was studied in monometallic catalysts. Ni/CeO₂Al₂O₃ was identified as the catalyst more resistant to deactivation, likely due to its higher oxygen mobility, and selected for further tests. Then, bimetallic catalysts were produced by impregnation of noble metals (Pd, Pt or Rh) on the Ni catalyst supported on CeO₂Al₂O₃. Co-impregnation of Rh and Ni on the CeO₂Al₂O₃ support represented a further improvement in the catalytic activity and stability respect to the monometallic catalyst, leading to stable gas compositions close to thermodynamic equilibrium due to the favourable RhNi interactions. RhNi/CeO₂Al₂O₃ is therefore a promising catalyst to produce a hydrogen-rich gas from bio-oil SR.     

Oxidative steam reforming of ethanol over Rh based catalysts in a micro-channel reactor

Oxidative steam reforming of ethanol (OSRE) was studied over Rh/CeO₂/Al₂O₃ catalysts in a micro-channel reactor. First, the catalyst support, Al₂O₃, was deposited on to the metallic substrate by washcoating and then the CeO₂ and active metal were sequentially impregnated. The effect of support composition as well as active metal composition on oxidative steam reforming of ethanol in a micro-channel reactor was studied at atmospheric pressure, with water to ethanol molar ratio of 6 and oxygen to ethanol molar ratio ranging from 0.5 to 1.5, over a temperature range of 350-550 °C. Ceria added to 1%Rh/Al₂O₃ showed higher activity and selectivity than 1%Rh/Al₂O₃ alone. Out of the various catalysts tested, 2%Rh/20%CeO₂/Al₂O₃ performed well in terms of activity, selectivity and stability. The OSRE performance was compared with that of SRE over 2%Rh/20%CeO₂/Al₂O₃ catalyst at identical operating conditions. Compared to SRE, the activity in OSRE was higher; however the selectivity to desired products was slightly lower. The H₂ yield obtained in OSRE was ∼112 m³ kg⁻¹ h⁻¹, as compared to ∼128 m³ kg⁻¹ h⁻¹ in SRE. The stability test performed on 2%Rh/20%CeO₂/Al₂O₃ at 500 °C for OSRE showed that the catalyst was stable for ∼40 h and then started to deactivate slowly. The comparison between packed bed reactor and micro-channel reactor showed that the micro-channel reactor can be used for OSRE to produce hydrogen without any diffusional effects in the catalyst layer.     

Double oxalates of Rh(III) with Ni(II) and Co(II) – Effective precursors of nanoalloys for hydrocarbons steam reforming

Heteronuclear coordination compounds of d-metals are suitable single-source precursors for bimetallic nanoalloys, which often show extraordinary catalytic properties due to synergetic effect. In particular, Ni- and Rh-based catalysts are highly effective in low temperature steam reforming processes. Double oxalates of Rh with Ni and Co of the formula {[Rh(H₂O)₂(C₂O₄)μ-(C₂O₄)]₂M(H₂O)₂}·6H₂O (M = Ni, Co) were synthesized and structurally characterized. According to thermogravimetric analysis, the complexes decompose completely in He and H₂ atmospheres to form corresponding nanoalloys at ∼300 °C. The calcination in O₂ atmosphere leads to formation of spinel type mixed oxide. The supported Co–Rh/Al₂O₃ and Ni–Rh/Al₂O₃ catalysts were prepared by impregnation of double oxalate complexes in porous support with subsequent calcination and tested in propane low temperature steam reforming in CH₄ excess. The Co-containing catalyst showed comparable activity regarding to pure Rh/Al₂O₃ sample, while bimetallic Ni–Rh/Al₂O₃ catalyst revealed to be appreciably more active, than monometallic catalysts with higher active component loadings. Rh–Ni catalyst allowed for complete propane conversion at T ≈ 350 °C, whereas for Rh catalyst the temperature was T ≈ 410 °C, and Rh–Co did not reach complete C₃H₈ conversion at all.     

Hydrogen production from carbon dioxide reforming of methane over highly active and stable MgO promoted Co–Ni/γ-Al2O3 catalyst

CoNi/Al₂O₃ and MgCoNi/Al₂O₃ catalysts are investigated for hydrogen production from CO₂ reforming of CH₄ reaction at the gas hourly space velocity of 40,000 mL g⁻¹ h⁻¹. The MgO promoted CoNi/Al₂O₃ catalyst shows much higher conversions (97% for CO₂ and 95% for CH₄ at 850 °C) than the CoNi/Al₂O₃ catalyst. In addition, the stability is maintained for 200 h in CO₂ reforming of CH₄. The outstanding catalytic activity and stability of the MgO promoted CoNi/Al₂O₃ catalyst is mainly due to the basic nature of MgO, an intimate interaction between Ni and the support, and rapid decomposition/dissociation of CH₄ and CO₂, resulting in preventing coke formation in CO₂ reforming of CH₄.     

Low-temperature CO2 reforming of methane over Ni supported on ZnAl mixed metal oxides

Ni catalysts supported on mixed ZnOAl₂O₃ and on pure ZnO and Al₂O₃ were prepared, characterized by XRD, TPR, and XPS, and tested in long-term methane dry reforming at low temperature (400 °C). Depending on Zn/Al ratio in the supports, the catalysts varied in their physico-chemical properties and exhibited different trends in their on-stream catalytic activity. Catalysts with high alumina content consist of a mixture of alumina and zinc aluminate phases with metallic Ni particles on their surface. These samples show medium activity for reforming and high on-stream stability. The catalysts on mixed Zn-rich supports were more active than those on Al-rich supports and exhibited maxima in their activity after 30–40 h on stream, while Ni on pure ZnO possessed very low activity. Such contrast in performance of Zn-rich catalysts was explained by detected transformation of initially formed NiZn alloy to a mixture of Ni and Ni₃ZnC_0.7 particles that are assumed to have higher activity for reforming. Moreover, the size of Ni-containing particles on Zn-rich supports decreased under reaction conditions resulting in higher Ni dispersion.     

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 Ni catalysts supported on Al2O3, MgO–CaO–Al2O3 and La2O3–Al2O3 for the dry reforming of ethane

CO₂ utilization through the activation of ethane, the second largest component of natural and shale gas, to produce syngas, has garnered significant attention in recent years. This work provides a comparative study of Ni catalysts supported on alumina, alumina modified with CaO and MgO, as well as alumina modified with La₂O₃ for the reaction of dry ethane reforming. The calcined, reduced and spent catalysts were characterized employing XRD, N₂ physisorption, H₂-TPR, CO₂-TPD, TEM, XPS and TPO. The modification of the alumina support with alkaline earth oxides (MgO and CaO) and lanthanide oxides (La₂O₃), as promoters, is found to improve the dispersion of Ni, enhance the catalyst's basicity and metal-support interaction, as well as influence the nature of carbon deposition. The Ni catalyst supported on modified alumina with La₂O₃ exhibits a relatively stable syngas yield during 8 h of operation, while H₂ and CO yields decrease substantially for Ni/Al₂O₃.     

Effect of phosphorous addition to Rh-supported catalysts for the dry reforming of methane

The dry reforming (DR) of methane has been studied over Rh-based catalysts modified by phosphorous addition in order to investigate the possibility to enhance their resistance to sulfur poisoning. In particular, three catalysts have been prepared: i) by dispersing phosphorous with rhodium on La-stabilized γ-Al₂O₃; ii) by stabilizing γ-Al₂O₃ with phosphorous and then dispersing rhodium; iii) by dispersing rhodium on an amorphous AlPO₄ support. Rh supported on La-stabilized γ-Al₂O₃ has been used as a reference catalyst.Fresh and used catalysts and their corresponding supports have been characterized by ICP-MS, XRD, BET, H₂-TPR, CO chemisorption, CO₂-TPD, TG analysis and Raman spectroscopy. Phosphorous addition to the supports increases their surface acidity and inhibits CO₂ activation, thus depressing both activity and resistance to coke formation of the corresponding supported Rh catalysts during methane DR. On the contrary, catalysts supported on basic La-promoted alumina provide a stable syngas production approaching equilibrium at 750–800 °C. Small amounts of phosphorous co-impregnated with rhodium increase the noble metal dispersion, but do not significantly impact on the catalyst activity.Transient and steady state S-poisoning experiments during methane DR suggest that sulfur directly attacks and bonds to Rh active sites, causing a rapid drop of syngas production even at low S-contents. A secondary poisoning effect is induced by sulfur that causes the rapid formation of some amorphous coke, which is almost absent under S-free operation on the reference Rh catalyst.     

Tungsten(VI) oxide supported rhodium nanoparticles: Highly active catalysts in hydrogen generation from ammonia borane

Herein, we report the use of tungsten(VI) oxide (WO₃) as support for Rh⁰ nanoparticles. The resulting Rh⁰/WO₃ nanoparticles are highly active and stable catalysts in H₂ generation from the hydrolysis of ammonia borane (AB). We present the results of our investigation on the particle size distribution, catalytic activity and stability of Rh⁰/WO₃ catalysts with 0.5%, 1.0%, 2.0% wt. Rh loadings in the hydrolysis reaction. The results reveal that Rh⁰/WO₃ (0.5% wt. Rh) is very promising catalyst providing a turnover frequency of 749 min^?1 in releasing 3.0 equivalent H₂ per mole of AB from the hydrolysis at 25.0 °C. The high catalytic activity of Rh⁰/WO₃ catalyst is attributed to the reducible nature of support. The report covers the results of kinetics study as well as comparative investigation of activity, recyclability, and reusability of colloidal(0) nanoparticles and Rh⁰/WO₃ (0.5 % wt. Rh) catalyst in the hydrolysis reaction.     

Improving the hydrothermal stability and hydrogen selectivity of Ni-Cu based catalysts for the aqueous-phase reforming of methanol

Non-precious metal catalysts suitable for hydrogen production via aqueous phase reforming (APR) of methanol show important technical and commercial value in the development of distributed, small/micro-scale on-site hydrogen production systems. They still face the challenges of reduced activity and stability due to sintering and oxidation of active metal nanoparticles, change of the surface state and collapse of the pore structure of used supports under hydrothermal conditions. To solve these problems, a series of ZnO/Ni-xCu/Al₂O₃ (x = 0, 2, 4, 6, 8, 10) catalysts were prepared by a simple impregnation method in this work. The addition of Cu improved the reducibility of NiO, and promoted the formation of smaller and more dispersed metal particles on the surface of Al₂O₃, facilitating hydrogen production and hindering methane formation. Among them, the highest average hydrogen production rate (362.1 μmol‧min⁻¹‧gcat⁻¹) and the highest hydrogen selectivity (99%) were reached using ZnO/Ni-8Cu/Al₂O₃ catalyst, which were 1.6 times and 20.7% higher than those obtained on the mono-metallic ZnO/Ni/Al₂O₃ catalyst, respectively. On the other hand, the modification of Ni-8Cu/Al₂O₃ with ZnO prevented effectively the reaction of surface water with Al₂O₃ and inhibited the formation of boehmite phase, leading to dramatical improvement of its stability during APR of methanol with a prolonged lifetime (72 h) by 6 times. This new developed ZnO/Ni-xCu/Al₂O₃ catalysts offer great potential for the development of commercial catalysts to produce hydrogen from APR of methanol.     

Steam reforming of acetic acid for hydrogen production over attapulgite and alumina supported Ni catalysts: Impacts of properties of supports on catalytic behaviors

In this study, the potential of attapulgite (ATTP) as the support of nickel catalysts for steam reforming of acetic acid to produce hydrogen were evaluated. Ni/Al₂O₃ was prepared and evaluated for comparison. The results showed that ATTP had a much lower specific surface area and a lower thermal stability than alumina. Nevertheless, the interaction between nickel and ATTP was much weaker than that of nickel with alumina. As a result, the Ni/ATTP catalyst had superior activity than the Ni/Al₂O₃ catalyst, especially at low nickel loading. Ni/Al₂O₃ was more stable than Ni/ATTP. The fibrous coke, which was probably catalytic coke, formed over Ni/Al₂O₃ did not cause the rapid deactivation of the catalyst, while the amorphous coke formed over Ni/ATTP catalyst, which was probably the polymeric coke, rapidly deactivated the catalyst. The coke species contained COOH, CO, aliphatic structure and aromatic ring structures. In addition, the effects of these two carriers on the steam reforming mechanism were investigated by the in-situ DRIFTS.