Ni supported on MgO modified attapulgite as catalysts for hydrogen production from glycerol steam reforming

A series of Mg-modified Ni/Attapulgite (ATP) catalysts have been prepared by impregnation method for glycerol steam reforming to produce hydrogen. The physicochemical properties of catalysts were characterized using various techniques including N₂ physical adsorption analysis, XRD, H₂-TPR, SEM, TEM and NH₃-TPD. The results of N₂ physical adsorption indicated MgO modified Ni-based catalysts had unique mesostructure, resulting in the high metal dispersion and interaction between active metal and support as proven by XRD, TEM and H₂-TPR. Results of glycerin reforming experiments showed that Ni/10MgO/ATP catalyst had the highest activity than that of the other catalysts. Ni/10MgO/ATP catalyst had the smallest Ni average crystal size (10.1 nm) and the highest surface area (110.31 m²/g). These excellent properties made it show the enhanced glycerol conversion (94.71%) and a higher H₂ yield (88.45%) and the longest stability (30 h) during glycerol steam reforming (GSR) at 600 °C, W/G = 3, and WHSV = 1 h^?1. The used catalysts after 60 h of glycerin reforming experiments were also investigated by XRD, SEM, TEM, Roman and TG-DTG. The results indicated that the addition of Mg significantly inhibited the sintering of nickel grains and the formation of amorphous carbon. Therefore, Ni/10MgO/ATP catalyst increased the activity of the catalyst and extended the life of the catalyst.     

Sustainable and selective hydrogen production by steam reforming of bio-based ethylene glycol: Design and development of Ni–Cu/mixed metal oxides using M (CeO2, La2O3, ZrO2)–MgO mixed oxides

Hydrogen (H₂) production in a clean and green manner via renewable sources is at present of great interest. Ethylene glycol, a bio-based feedstock, offers a sustainable route for high purity H₂ production. In the current investigation, MgO based mixed metal oxides containing CeO₂, La₂O₃ and ZrO₂ were synthesized and used to support 20 wt% Ni–Cu (1:1). The impacts of altering support characteristics on catalytic behavior have been studied and compared in H₂ synthesis via ethylene glycol steam reforming (SR), employing various characterization techniques such as XRD, SEM, EDX, TEM, H₂-TPR, H₂-TPD, TG-DSC and BET. Further, high resolution XPS studies were performed to explore the valence states and effectiveness of surface engineering of the catalysts. Assessment of the efficacy of catalysts was done via several parameters such as reactant conversion, H₂ concentration and long-term stability. All the synthesized materials produced encouraging results with high H₂ yield and conversion under the said operating conditions [T- 623 to 773 K; GHSV - 3120 to 6240 h^?1; P - 0.1 MPa; S/C - 3 to 7.5 mol/mol]. Amongst the three catalysts, Ni–Cu/La₂O₃–MgO and Ni–Cu/CeO₂–MgO exhibited superior behavior for high H₂ production. Ni–Cu/La₂O₃–MgO was better in comparison to Ni–Cu/CeO₂–MgO in terms of reactant conversion whereas Ni–Cu/CeO₂–MgO showed highest H₂ concentration (98 mol %) and improved stability along with absence of carbon deposition owing to its high mobile oxygen vacancies in its lattice. The highly active cubic CeO₂ species and its long-term durability (up to 8 cycles) owing to its exceptional redox property further justified its efficacy. The optimized process showed that at T = 773 K, GHSV = 3120 h^?1, S/C = 4.5 mol/mol for Ni–Cu/La₂O₃–MgO and Ni–Cu/CeO₂–MgO and at T = 773 K, GHSV = 3120 h^?1, S/C = 6 mol/mol and for Ni–Cu/ZrO₂–MgO, maximum H₂ concentration was obtained. At the end, reaction pathway followed by the catalysts was proposed.     

Zirconia supported nickel catalysts for glycerol steam reforming: Effect of zirconia structure on the catalytic performance

The effect of the zirconia structure in Ni/ZrO₂ catalysts on the glycerol steam reforming (GSR) reaction was studied. A tetragonal zirconia support was synthesized via a hydrolysis technique and loaded with 5 wt% Ni via a wet-impregnation method. Similarly, a commercial monoclinic zirconia support was also impregnated with 5 wt% Ni. Following calcination at 600 °C, physico-chemical properties of the prepared catalysts were investigated by X-Ray Diffraction (XRD), H₂-Temperature Programmed Reduction (H₂-TPR) and CO₂-Temperature Programmed Desorption (CO₂-TPD) techniques. The catalysts were then tested in the GSR reaction in the 400–700 °C range with a steam to glycerol molar ratio of 9:1 and a flow rate of 0.025 mL/min. The monoclinic catalyst exhibited a better performance giving higher hydrogen yields and glycerol conversions. This was attributed to an improved reducibility of Ni in this catalyst. Stability tests at 600 °C revealed the deactivation of the tetragonal catalyst during 6 h as a result of the formation of encapsulating coke which blocked active Ni metal sites. The monoclinic catalyst, exhibiting the formation of only filamentous coke, remained relatively stable for 24 h.     

Effects of metal loading and support modification on the low-temperature steam reforming of ethanol (LTSRE) over the Ni–Sn/CeO2 catalysts

This article presents the effect of metal loading and support modification with MgO on low-temperature steam reforming of ethanol (LTSRE) over Ni–Sn/CeO₂ catalysts prepare by a single-pot solution combustion synthesis (SCS) method. Atmospheric pressure activity study of these catalysts (0.5 g) is performed at different temperatures (200–400 °C), H₂O:EtOH = 12: 1 mol ratio, and feed flow rate 0.1 ml/min. After 10 h TOS at 400 °C, NiSn(5)/CM12 catalyst with 5 wt.% total metal loading, optimal Sn (Ni:Sn = 14:1), and Ce:Mg = 1:2 mol ratio shows EtOH conversion 100% and H₂ selectivity 70% with low coke deposition. Physicochemical characterizations (XRD, Raman, FESEM, TEM, and N₂ adsorption-desorption) reveal that addition of MgO in CeO₂ and an optimal amount of Sn decrease both Ni and support particle sizes while oxygen storage capacity (OSC) of the support increases (by XPS). Alkaline characteristics of MgO reduces support's acidity and improves active metal-support interaction, as evaluated by NH₃-TPD and H₂-TPR.     

Co-production of hydrogen and carbon nanomaterials using NiCu/SBA15 catalysts by pyrolysis of a wax by-product: Effect of Ni–Cu loading on the catalytic activity

The simultaneous production of H₂ and carbon nanomaterials (CNMs) over NiCu/SBA15 catalysts with different Ni–Cu contents (10, 20, 30, 40 and 50 wt%) was investigated using the pyrolysis-catalysis process of paraffin wax. The fresh and spent catalysts were characterized by various techniques including H₂-TPR, XRD, TEM, Raman spectroscopy and BET surface area. TEM observations showed that broad particle size distributions were formed in fresh 40NiCu/SBA15 and 50NiCu/SBA15 catalysts, while catalysts with smaller Ni–Cu contents displayed better metals dispersion. We found that the catalyst activity is related to the type of carbon nanomaterials, catalyst particle size, and catalyst loading with Ni–Cu. Also, the largest yield of H₂ and CNMs was achieved using the 30NiCu/SBA15 catalyst. NiCu/SBA15 catalysts with Ni-Cu contents of 30–50 wt% exhibited good catalytic stability and similar activity in terms of H₂ yield, especially at reaction time above 225 min. Small diameters carbon nanofibers (CNFs) were produced over the 10NiCu/SBA15 catalyst, while a mixture of CNFs and carbon nano-onions (CNOs) was produced using catalysts with Ni-Cu loadings of 20–50 wt%. The generation of octopus-like CNFs over large catalyst particles was associated with the observed catalytic stability of H₂ production. Raman spectroscopy and XRD analyses demonstrated the formation of the best quality CNMs using the 20NiCu/SBA15 catalyst.     

Insights into the long-term stability of the magnesia modified H-ZSM-5 as an efficient solid acid for steam reforming of dimethyl ether

The long-term performance of the bifunctional catalyst composed of MgO-modified H-ZSM-5 and Cu/ZnO/Al₂O₃ for steam reforming of dimethyl ether (SRD) is studied under the same conditions. Although the surface chemical state and acid property of 1.55–2.47 wt% MgO modified H-ZSM-5 are almost the same, a significant impact of MgO contents on the stability of the bifunctional catalyst is observed from the 50 h SRD results. The initial dimethyl ether conversion (around 100%) and H₂ yield (∼95%) over the optimal bifunctional catalyst with 2.17 wt% MgO modified H-ZSM-5 is still kept over 90% at 50 h. Combining the characterization data of spent catalysts and SRD results, the synergetic effect between the MgO-modified H-ZSM-5 and Cu/ZnO/Al₂O₃ is rigorously revealed as the key factor in determining the stability of the bifunctional catalyst for SRD. These results demonstrate that MgO-modified H-ZSM-5 is a promising and efficient solid acid for SRD.     

Low-temperature catalytic conversion of greenhouse gases (CO2 and CH4) to syngas over ceria-magnesia mixed oxide supported nickel catalysts

Running dry reforming of methane (DRM) reaction at low-temperature is highly regarded to increase thermal efficiency. However, the process requires a robust catalyst that has a strong ability to activate both CH₄ and CO₂ as well as strong resistance against deactivation at the reaction conditions. Thus, this paper examines the prospect of DRM reaction at low temperature (400–600 °C) over CeO₂–MgO supported Nickel (Ni/CeO₂–MgO) catalysts. The catalysts were synthesized and characterized by XRD, N₂ adsorption/desorption, FE-SEM, H₂-TPR, and TPD-CO₂ methods. The results revealed that Ni/CeO₂–MgO catalysts possess suitable BET specific surface, pore volume, reducibility and basic sites, typical of heterogeneous catalysts required for DRM reaction. Remarkably, the activity of the catalysts at lower temperature reaction indicates the workability of the catalysts to activate both CH₄ and CO₂ at 400 °C. Increasing Ni loading and reaction temperature has gradually increased CH₄ conversion. 20 wt% Ni/CeO₂–MgO catalyst, CH₄ conversion reached 17% at 400 °C while at 900 °C it was 97.6% with considerable stability during the time on stream. Whereas, CO₂ conversions were 18.4% and 98.9% at 400 °C and 900 °C, respectively. Additionally, a higher CO₂ conversion was obtained over the catalysts with 15 wt% Ni content when the temperature was higher than 600 °C. This is because of the balance between a high number of Ni active sites and high basicity. The characterization of the used catalyst by TGA, FE-SEM and Raman Spectroscopy confirmed the presence of amorphous carbon at lower temperature reaction and carbon nanotubes at higher temperature.     

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.     

Highly stable M/NiO–MgO (M = Co,Cu and Fe) catalysts towards CO2 methanation

NiO–MgO nanocomposites are synthesized using solution combustion, sonochemical, and co-precipitation synthesis to understand the catalytic activity of CO₂ methanation. Excellent particle size distribution was noticed with the sonochemical routed synthesis method, and the CO₂ conversions are found to be better with the same synthesis protocol. Surface modifications in NiO–MgO composite were incorporated by doping M (M = Co, Fe, and Cu). The active catalysts are characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) to understand physical, structural properties and surface morphology of the nanocomposites. All catalysts showed excellent catalytic activity for the conversion of CO₂ to methane and selectivity towards methane to be higher than 85%. However, 2%Co/NiO–MgO showed the lowest activation energy of about 43 ± 2 kJ mol⁻¹ among other synthesized catalysts. The mechanism of CO₂ methanation was investigated with the inputs from temperature programming reduction with H₂ (H₂-TPR), and temperature programming desorption with CO₂ (CO₂-TPD) studies. Detailed reaction mechanism and kinetics are investigated for all doped catalysts. M/NiO–MgO offered excellent stability up to 50 h reaction time with high CO₂ conversions and CH₄ selectivities.     

Cobalt doped TiO2: A stable and efficient photocatalyst for continuous hydrogen production from glycerol: Water mixtures under solar light irradiation

Glycerol is the main by-product during the trans-esterification of vegetable oils to biodiesel. In this study, we investigate the process of photocatalytic hydrogen production from glycerol aqueous solution, with the use of cobalt doped TiO₂ photocatalyst under solar light irradiation. Cobalt doped TiO₂ photocatalysts are prepared by impregnation method and these catalysts are characterized by XRD, EDAX, DRS, TEM, EPR and XPS techniques. DRS studies clearly show the expanded photo response of TiO₂ into visible region on impregnation of Co²⁺ ions on surface of TiO₂. XPS studies also show change in the binding energy values of O1s, Ti 2p and Co 2p, indicating that Co²⁺ ions are in interaction with TiO₂. Maximum hydrogen production of 220 μ mol h⁻¹ g⁻¹ is observed on 2 wt% cobalt doped TiO₂ catalysts in pure water under solar irradiation. A significant improvement in hydrogen production is observed in glycerol: water mixtures; and maximum hydrogen production of 11,021 μ mol h⁻¹ g⁻¹ is obtained over 1 wt% cobalt doped TiO₂ in 5% glycerol aqueous solutions. Furthermore, to evaluate some reaction parameters such as cobalt wt% on TiO₂, glycerol concentration, substrate effect (alcohols) and pH of the solution on the hydrogen production activity are systematically investigated. When the catalysts are examined under UV irradiation, a 3–4 fold increase in activity is observed where this activity seems to decrease with time; however, a continuous activity is observed under solar irradiation on these catalysts. The decreased activity could be ascribed the loss of cobalt ions under UV irradiation, as evidenced by EDAX and TEM analysis. A possible explanation for the stable and continuous activity of cobalt doped TiO₂ photocatalysts under solar irradiation is proposed.     

Preparation and improvement of the mesoporous nanostructured nickel catalysts supported on magnesium aluminate for syngas production by glycerol dry reforming

Dry reforming of glycerol is an interesting method for syngas production due to its H₂/CO ≈ 1 that is suitable for FT synthesis. In this study, the performance of the Ni/MgO.Al₂O₃ catalysts with different nickel contents was investigated in glycerol dry reforming. The MgO.Al₂O₃ carrier was prepared by a simple sol-gel method and the nickel-based catalysts were synthesized by the wet impregnation method. The prepared catalysts possessed high BET surface area and pore volume. The TPR analysis showed a strong interaction between Ni and the catalyst support. The results demonstrated that the glycerol conversion decreased by increasing in CO₂/glycerol (GRR) molar ratio. All the prepared samples showed high stability in glycerol dry reforming during 25 h of reaction, indicating the high resistance of the catalysts against carbon formation. Also, 10 wt%Ni/MgO.Al₂O₃ catalysts possessed the highest catalytic performance (52% of glycerol conversion at 750 °C) due to the high dispersion of nickel on the prepared carrier.     

Conversion of sugarcane bagasse to gaseous and liquid fuels in near-critical water media using K2O promoted Cu/γ-Al2O3–MgO nanocatalysts

Bagasse conversion to H₂, CO and light gaseous hydrocarbons as gaseous fuels, and higher alcohols and ethers as liquid fuels and fuel additives were performed in a basic water medium with near-critical condition in presence of potassium promoted Cu/γ-Al₂O₃–MgO catalysts. The catalysts were extensively characterized using ICP, XRD, TPR, BET, CO chemisorption and TEM techniques. In order to investigate support stability at reaction condition, XRD test also was carried out for used catalysts. Maximum dispersion of 48% and minimum average particles sizes of 8.4 nm were obtained for Cu20–K7.5/γ-Al₂O₃–MgO catalyst. Copper and potassium effects on quality and quantity of gaseous and liquid products were investigated. The maximum amounts of H₂ (10 mmol g⁻¹ of bagasse) and total produced gases (41 mmol g⁻¹ of bagasse) were obtained with unpromoted Cu20/γ-Al₂O₃–MgO catalyst. Addition of K increased the bagasse conversion to liquid fuels. Potassium made the process more selective for alcohols and ethers production. Maximum amount of alcohols and ethers (83.3 mmol g⁻¹ of bagasse) was obtained for Cu20–K7.5/γ-Al₂O₃–MgO catalyst.     

Mn-induced Cu/Ce catalysts with improved performance for CO preferential oxidation in H2/CO2-rich streams

A series of xMnCu/Ce catalysts with constant low Cu loading of 1 wt% were prepared by the simple impregnation method. The obtained catalysts were characterized by XRD, BET, H₂-TPR and XPS, and the preferential oxidation of CO was evaluated in CO₂/H₂-rich atmospheres. It was shown that partial Mn and Cu could be incorporated into the Ceria lattice, forming surface ternary Cu–Mn–Ce oxide solid solutions. At Mn/Cu = 0.6, the catalyst presented strong interaction among Cu, Mn and Ce, had more Ce³⁺ and Mn⁴⁺ at the surface and showed the best catalytic performance, making CO conversion increase of 23.57% at 90 °C as compared with the Cu/Ce catalyst. For CO-Prox, the highest CO conversion was 94.7% with an oxidation selectivity of 78.9% at 125 °C. At this temperature, the catalyst revealed stable catalytic performance for a total TOS of 205 h. In addition, with CO/Ar as feed gas, CO conversion was 100%, confirming the negative effects of CO₂/H₂.     

Effect of copper loading on copper-ceria catalysts performance in CO selective oxidation for fuel cell applications

Copper–ceria catalysts with three different Cu loadings (1, 7 and 15 wt%) were prepared by incipient wet impregnation, dried at 120 °C and calcined in air at 500 °C. The as-prepared catalysts were characterized by XRD, BET, Diffuse Reflectance Spectroscopy (DRS–UV–visible), Raman spectroscopy, CO and H₂-TPR, CO-TPR, CO-TPD and Oxygen Storage Capacity (OSC) measurements (with CO and O₂ concentration step-changes). The results indicated a good dispersion of copper for catalysts with 1 and 7 wt% Cu; however, bulk CuO was present for catalyst with 15 wt% Cu loading. Catalyst with 7 wt% Cu was observed to have very high capacity to release lattice oxygen to oxidize CO at low temperature. Activity results for CO oxidation in the absence and in the presence of 60% H₂, demonstrated a very similar performance for catalysts with 7 and 15 wt% Cu (both with T₁₀₀ = 112 °C), and much better than that of catalyst loaded with 1 wt% Cu. Catalyst with 7 wt% of copper shows very high activity (100% in a wide temperature window) and selectivity (higher than 85%), which makes an attractive for its use in purification of hydrogen for fuel cell applications. The presence of a mixture of CO₂ and H₂O inhibited catalyst activity, with CuO/CeO₂ catalyst with 7 wt% Cu exhibiting the best performance in the overall reaction temperature range. This could be attributed to the presence of highly disperse copper, only part of it in deep interaction with ceria. The effect of O₂/CO ratio (λ) and the potential reversibility of the inhibitory effect of CO₂ and H₂O were also investigated.     

Alumina supported Au/Y-doped ceria catalysts for pure hydrogen production via PROX

Gold catalysts on Y-doped ceria dispersed on high surface area γ-Al₂O₃ were synthesized and tested in preferential CO oxidation in hydrogen rich stream (PROX). The effect of ceria loading (10, 20 or 30 wt%) was studied. The gold catalyst with the lowest ceria amount exhibited the highest PROX activity. The addition of Y₂O₃ (1 wt%) led to improved performance. The most favorable effect was observed in the sample with 20 wt% ceria amount. This gold catalyst showed good PROX activity and stability in the presence of CO₂ and water. Catalysts characterization by XRD, HRTEM/HAADF, XPS and H₂-TPR was used to elucidate the relationship between the chemical composition, state of gold, support features and catalytic properties.     

Modification effect of natural mixed rare earths on Co/γ-Al2O3 catalysts for CH4/CO2 reforming to synthesis gas

The study first investigated the modification effect of natural mixed rare earths (MRE) on cobalt catalysts for CH₄/CO₂ reforming to synthesis gas. The Co/γ-Al₂O₃ catalysts modified with the natural mixed rare earths were synthesized by the impregnation method, and characterized via ICP, BET, XRD, H₂-TPR, TEM and TG–DSC techniques. The result showed that the addition of mixed rare earths enhanced the anti-sintering ability of metallic cobalt after reduction and improved anti-coke performance of the catalysts via the synergic effect of mixed rare earths. The 20% Co/γ-Al₂O₃ catalyst promoted by the appropriate natural mixed rare earths exhibited good activity and stability with low carbon formation at 800 °C for 320 h reaction.     

Production of CO-rich hydrogen gas from glycerol dry reforming over La-promoted Ni/Al2O3 catalyst

Dry reforming of glycerol has been carried out over alumina-supported Ni catalyst promoted with lanthanum. The catalysts were characterized using EDX, liquid N₂ adsorption, XRD technique as well as temperature-programmed reduction. Significantly, catalytic glycerol dry reforming under atmospheric pressure and at reaction temperature of 1023 K employing 3 wt%La–Ni/Al₂O₃ catalyst yielded H₂, CO and CH₄ as main gaseous products with H₂:CO < 2.0. Post-reaction, XRD analysis of used catalysts showed carbon deposition during glycerol dry reforming. Consequently, BET surface area measurement for used catalysts yielded 10–21% area reduction. Temperature-programmed gasification studies with O₂ as a gasification agent has revealed that La promotion managed to reduce carbon laydown (up to 20% improvement). In comparison, the unpromoted Ni/Al₂O₃ catalyst exhibited the highest carbon deposition (circa 33.0 wt%).     

Hydrogen release mechanism and performance of ammonia borane catalyzed by transition metal catalysts Cu‐Co/MgO(100)

The catalytic dehydrogenation of ammonia borane (NH₃BH₃, AB) molecule is most frequently employed by metal catalysts, but a reliable dehydrogenation mechanism in molecular level has yet to be fully illuminated. Herein, adopting the density functional theory (DFT) method, the dehydrogenation mechanism and performance of NH₃BH₃ under the transition metal catalysts (Cu/MgO, Co/MgO, CuCo/MgO) were studied. The calculated results show that the dehydrogenation mechanism of AB refers to stepwise dehydrogenation mechanism: AB is adsorbed in the transition metal catalysts firstly, then one H(N) atom transferred to H(B) of ―BH₃ and to form H₂ molecule via the broken of B―H and N―H bond, finally, H₂ molecule desorption from the catalyst complexes. Among the transition metal catalysts, CuCo/MgO have the perfect catalytic activity in dehydrogenation reaction of NH₃BH₃, its barrier energy of the feasible pathway (path A) is 22.26 kcal/mol, which is lower than the barrier energy of AB‐Cu/MgO(28.13 kcal/mol), AB‐Co/MgO(27.46 kcal/mol), and the results of thermogravimetric analysis further verified the reasonability of DFT calculational results. Besides, partial density of states calculational results show the electron orbital hybridization of Cu, Co atom may account for the excellent catalytic performance of CuCo/MgO(100) compared with the Cu/MgO(100) and Co/MgO(100) in dehydrogenation process of AB.     

Cooperative role of cobalt and gallium under the ethanol steam reforming on Co/CeGaOx

The performance of gallium promoted cobalt-ceria catalysts for ethanol steam reforming (ESR) was studied using H₂O/C₂H₅OH = 6/1 mol/mol at 500 °C. The catalysts were synthetized via cerium-gallium co-precipitation and wetness impregnation of cobalt. A detailed characterization by N₂-physisorption, XRD, H₂-TPR and TEM allowed the normalization of contact time and rationalization of the role of each catalysts component for ESR. The gallium promoted catalyst, Co/Ce₉₀Ga₁₀O_x, was more efficient for the ethanol conversion to H₂ and CO₂, and the production of oxygenated by-products (such as, acetaldehyde and acetone) than Co/CeO₂. The catalytic performance is explained assuming that: (i) bare ceria is able to dehydrogenate ethanol to ethylene; (ii) Ce–O–Ga interface catalyzes ethanol reforming; (iii) both Ce–O–Co and Ce–O–Ga interfaces takes part in acetone production; and (iv) cobalt sites further allow C–C scission. It is suggested that a cooperative role between Co and Ce–O–Ga sites enhance the H₂ and CO₂ yields under ESR conditions.     

High performance Ni exsolved and Cu added La0.8Ce0.2Mn0.6Ni0.4O3-based perovskites for ethanol steam reforming

La_0.8Ce_0.2Mn_0.6Ni_0.4O₃ with (LCMN@CuO) and without (LCMN) CuO addition are prepared by solution methods, followed by reduction in 5% H₂–N₂ stream at 650 °C to form Ni exsolved and CuO reduced catalysts, LCMN@Ni and LCMN@Ni/Cu, for ethanol (EtOH) steam reforming (ESR). The catalysts are characterized by X-ray diffraction (XRD), scanning and transmission electron microscopies (SEM and TEM), temperature programmed reduction (H₂-TPR), X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy etc., and are evaluated for ESR with a steam/carbon ratio of 3 and a weight hourly space velocity (WHSV) of 4 h⁻¹ at temperatures between 500 and 700 °C. Ni exsolution and CuO reduction are confirmed on the substrates in LCMN@Ni and LCMN@Ni/Cu. Both the catalysts demonstrate a complete conversion of EtOH, forming mainly H₂, CO₂, CO and CH₄. And increasing temperature to 700 °C increases the yields of H₂ and CO to the levels about 90% and 40%, respectively, at the cost of CH₄; and such performance remains unchanged for 30 h. These results indicate that both LCMN@Ni and LCMN@Ni/Cu are promising catalysts for ESR, the main difference between them is that the latter is more chemically stable and more resistant to carbon deposition under ESR conditions.