Biogas dry reforming over Ni-Al catalyst: Suppression of carbon deposition by catalyst preparation and activation

Biogas dry reforming is as an alternative renewable route for the hydrogen production. However, the major drawback of this process is the catalyst deactivation by carbon deposition and sintering. In this work, Ni-Al catalysts were studied aiming to suppress the carbon deposition in the dry reforming of biogas. The catalysts were prepared by coprecipitation and evaluated the washing step. The reactions were carried out with unreduced and reduced catalysts in a fixed bed tubular reactor using a synthetic biogas (60% CH₄ and 40% CO₂). The washing and activation steps influenced the characteristics of the catalysts and the catalytic properties in the biogas reforming. The unwashed sample resulted in an oxide containing potassium nickelate with high basicity and low surface area. Both washed samples, reduced and unreduced, showed a high amount of carbon formation, whereas no carbon formation was observed in the unwashed samples for the reactions in the temperature range of 500–750 °C. The unwashed and unreduced sample was the only one that maintained the activity during all the reaction time at 700 °C (40% CH₄ conversion and 75% CO₂ conversion), low coke amount and no evidence of sintering, which was confirmed by XRD, TPO, and SEM analyses. The carbon suppression was related to the nickelate phase and to the Ni carbide formation in the unwashed and unreduced catalyst. In summary, the carbon deposition in biogas dry reforming was completely controlled between 600 and 750 °C using the unwashed and unreduced Ni-Al catalyst.     

Influence of silica promotion on NiCe/MgAlSi catalysts for the oxy-steam reforming of biogas to syngas

This work has exploited the effects of silica on magnesium aluminum silicate supported NiCe based catalysts (NiCe/MgAlSi) prepared using sol-gel method followed by incipient wetness impregnation for syngas production through oxy-steam reforming (OSR) of biogas. Measurements investigating the effects of increasing Si/Al molar ratio (0–5) on activity and carbon deposition were performed in a once-through flow reactor at atmospheric pressure and temperatures of 600, 700, and 800 °C with a fixed GHSV of 45,000 ml g_cat⁻¹ h⁻¹ and molar feed ratio of CH₄/CO₂/O₂/H₂O = 1/0.67/0.1/0.3. The catalysts were characterized by N₂-physisorption, XRD, SEM, HRTEM, TGA, Raman, and ICP-OES. In the results, the addition of silica has been found to increase Ni crystallite sizes and decrease carbon deposition. Thus, NiCe/MgAlSi with Si/Al = 5 is promising, exhibiting high conversions of CH₄ (91.7%), CO₂ (80.4%), and H₂/CO ratio of 1.6 without carbon deposition and good stability for 120 h at 800 °C.     

Biogas dry reforming using Ni–Al-LDH catalysts reconstructed with Mg and Zn

The reconstruction of NiAl-LDH by incorporating Mg or Zn using a memory effect was investigated aiming to improve the basic properties of the catalysts and evaluated in the dry reforming of Biogas. Samples were characterized by XRD, CO₂?TPD, N₂-physisorption, TPR, and TPO. Biogas dry reforming experiments were carried out using a feed of CH₄/CO₂/N₂ = 1.5/1/7.5 in the temperature range of 500–750 °C with in situ reduced samples. The washing step strongly influences the LDH reconstruction. The unwashed samples showed the reconstruction of the LDH structure, presented a low specific area, and high basicity, responsible for decreasing carbon formation during reactions. The washed samples did not exhibit the LDH reconstruction property but showed a high specific area and low basicity. The metal used in the reconstruction influences the crystallinity, basicity, and reducibility of the materials. Samples with Zn showed higher crystallinity and reducibility, whereas the samples with Mg showed higher basicity. Among all the catalysts, reconstruction with Zn and subsequent washing leads to the best results with CH₄ and CO₂ conversion of 73% and 90%, respectively, and an H₂/CO ratio of approximately 2. This can be attributed to the Ni–Zn alloy formation and to the reducing properties suitable for the range between 600 and 700 °C. This catalyst showed the highest resistance to sintering in the stability test at 700 °C.     

Biogas reforming over La-promoted Ni/SBA-16 catalyst for syngas production: Catalytic structure and process activity investigation

Biogas, a mixture of CO₂/CH₄, is reasonable for conversion to syngas (H₂/CO) by dry methane reforming (DMR) reaction. The modification of Ni/SBA-16 with a lanthanum promoter using the co-impregnation technique is investigated in this study. The temperature of reaction (600–750 °C), La loading (3.85–11.56 wt%), and Ni loading (10–30 wt%) are the parameters that are varied for maximizing reaction conversions. The synthesized catalysts and SBA-16 supporting material were characterized by several methods before and after reaction. According to the analysis, the existence of La₂O₃ particles on the catalyst's surface has decreased the particle sizes, as well as enhanced their dispersion. Therefore, the maximum CH₄ conversion of 94.21%, CO₂ conversion of 90.12%, H₂ yield of 90.53%, and H₂/CO molar ratio of 2.03 are achieved using 20Ni-5.78La/SBA16 at 700 °C. Besides, this catalyst showed lower deposited coke and higher stability compared with other synthesized catalysts.     

Si-MCM-41 obtained from different sources of silica and its application as support for nickel catalysts used in dry reforming of methane

Si-MCM-41 molecular sieves are attractive for use as catalytic supports in reforming processes, requiring the development of catalysts that combine low cost, high activity and resistance to coking for viable conversion of biogas (CH₄ + CO₂) into higher added value products such as synthesis gas (H₂ + CO). In this work was synthesized Si-MCM-41 from a waste material (rice husk ash - RHA) and compared with Si-MCM-41 synthesized from a commercial silica source (tetraethylorthosilicate - TEOS). Both were evaluated as catalytic support in dry reforming of methane (DRM). Calcined Si-MCM-41 supports were wet impregnated with 10, 20 and 50% of nickel. DRM reactions were performed in a continuous-flow tubular reactor using a 1:1 CH₄:CO₂ molar mixture, at 700 and 800 °C, and WHSV of 30 L.h⁻¹g_cat⁻¹. The results confirmed that the Si-MCM-41 structure was successfully synthesized by the different methods. The best DRM results were obtained with the 20%Ni/Si-MCM-41_TEOS catalyst.     

Novel LaNi intercalated Egyptian bentonite clay for direct conversion of methane using CO2 as soft oxidant

Natural Egyptian bentonite clay intercalated with both La and Ni having different molar ratio (La: Ni = 2:1, 1:1 & 1:2) were prepared, saving 5mmole pillar/gm clay, using ultrasonic assistance method. The prepared catalysts were calcined at 450 and then reduced at 400 °C & 600 °C.Characterization of the prepared LaNi-PILC was achieved by X-ray diffraction (XRD), Furrier transform infrared spectroscopy (FTIR), N₂ adsorption desorption isotherm (BET) and H₂-temperature programmed reduction (H₂-TPR). The data confirm the success of intercalation process for both La & Ni in the lamellar structure of bentonite clay. The La: Ni molar ratio affected the specific surface area, Ni crystal size, dispersion and reducibility of the prepared catalyst. The reduction temperature had a great effect on the reactivity and product selectivity during CO₂/CH₄ reforming at different reaction temperatures (600–800 °C). Where, reduction at 400 °C gives rise to CH₄ oxidation reaction (MOR) with formaldehyde as a main product. While reduction at 600 °C enhances the activity and stability for CO₂ reforming of methane (CRM) and syngas production (H₂/CO ~ 1.19). The most active and stable LaNi_1:2-PILC₅ catalyst (CO₂ and CH₄ conversions reached 85% and 90% respectively) is superior with respect to the performance of PILC based catalysts reported in the literatures.     

Natural clay based nickel catalysts for dry reforming of methane: On the effect of support promotion (La,Al, Mn)

Fe modified natural clay supported Ni catalysts promoted with Lanthanum (La), aluminum (Al) and Manganese (Mn) were prepared by impregnation method. Calcined or reduced catalysts were characterized by Brunauer–Emmett–Teller (BET), X-ray diffraction (XRD), H₂-temperature programmed reduction (H₂-TPR) and CO₂-temperature programmed desorption (CO₂-TPD). The addition of La, Al and Mn obviously affected the specific surface area and catalyst basicity. The presence of La, Al and Mn resulted in smaller Ni⁰ crystallite size and further promoted Ni dispersion. Al-promoted catalysts improved the Ni reducibility compared to La and Mn-promoted catalysts. After a reduction step at 900 °C, the studied catalysts have been tested in dry reforming of methane (DRM) from 850 to 600 °C. Al-promoted Fe-clay based catalysts presented the best catalytic performance in DRM. Both CH₄ and CO₂ conversions, and H₂/CO molar ratio followed the trend of thermodynamic calculations. Furthermore all conversions and H₂/CO molar ratio were close to theoretical values that were also forecasted by thermodynamics by means of HSC Chemistry 5.0.     

Hydrogen-rich syngas production and carbon dioxide formation using aqueous urea solution in biogas steam reforming by thermodynamic analysis

Biogas is a renewable biofuel that contains a lot of CH₄ and CO₂. Biogas can be used to produce heat and electric power while reducing CH₄, one of greenhouse gas emissions. As a result, it has been getting increasing academic attention. There are some application ways of biogas; biogas can produce hydrogen to feed a fuel cell by reforming process. Urea is also a hydrogen carrier and could produce hydrogen by steam reforming. This study then employes steam reforming of biogas and compares hydrogen-rich syngas production and carbon dioxide with various methane concentrations using steam and aqueous urea solution (AUS) by Thermodynamic analysis. The results show that the utilization of AUS as a replacement for steam enriches the production of H₂ and CO and has a slight CO₂ rise compared with pure biogas steam reforming at a temperature higher than 800 °C. However, CO₂ formation is less than the initial CO₂ in biogas. At the reaction temperature of 700 °C, carbon formation does not occur in the reforming process for steam/biogas ratios higher than 2. These conditions led to the highest H₂, CO production, and reforming efficiency (about 125%). The results can be used as operation data for systems that combine biogas reforming and applied to solid oxide fuel cell (SOFC), which usually operates between 700 °C to 900 °C to generate electric power in the future.     

Cu substituted ZnAl2O4 ex-LDH catalysts for medium-temperature WGS – effect of Cu/Zn ratio and thermal treatment on catalyst efficiency

The effect of Cu/Zn ratio of ex-LDH oxide-based catalysts for medium–temperature water–gas shift reaction (MT–WGS) was investigated. A series of CuZnAl–LDH precursors with different Cu/Zn molar ratio were synthesized by co-precipitation and oxide (Zn,Cu)_xAl₂O₄ catalysts were prepared via subsequent calcinations at 380 °C or 700 °C. The prepared materials were characterized by X-ray fluorescence (XRF), X-ray diffraction (XRD), thermogravimetry with evolved gas analysis (TG/DTG/EGA), N₂ adsorption, N₂O chemisorption and temperature-programmed reduction (H₂-TPR). MT-WGS activity evaluation was carried out on the basis of measurements made in a differential reactor in kinetic regime. Catalysts’ properties were investigated and effect of composition (Cu/Zn molar ratio) and the calcination temperature of CuZnAl-LDH precursors on structural transformation, active surface area and MT-WGS rate constant was shown. The highest activity of (Zn,Cu)_xAl₂O₄ catalyst with Cu/Zn molar ratio of 1.5 calcined at mild conditions was attributed to easy reducible and accessible Cu surface.     

Effect of ionic liquid in Ni/ZrO2 catalysts applied to syngas production by methane tri-reforming

This study investigates the influence of ionic liquid in morphology, acid-base properties, metal dispersion and performance of 5%Ni/ZrO₂ catalysts in the methane tri-reforming reaction. Zirconia was prepared by precipitation and the catalysts by wet impregnation. The ionic liquid modified the acid and basic character of the catalysts and positively influenced the methane tri-reforming reaction efficiency. The reaction was evaluated with synthetic biogas and with stoichiometric feed molar ratio (CH₄: CO₂: H₂O: O₂ = 1:0.5:0.5:0.1 and CH₄: CO₂: H₂O: O₂ = 1:0.33:0.33:0.16). The Ni/ZrO₂ prepared with ionic liquid exhibits promising catalytic activity and stability in methane tri-reforming at 800 °C in 4 h run, without coke formation. An increase in the reaction temperature results in an increase of hydrogen yield and the methane conversion, reaching ∼85% at 850 °C. The presented results demonstrate that the tri-reforming reaction could be used for production of syngas with H₂/CO ratio appropriate for methanol synthesis.     

Calcium silicate-based catalytic filters for partial oxidation of methane and biogas mixtures: Preliminary results

Development and testing of catalytic filters for partial oxidation of methane to increase hydrogen production in a biomass gasification process constitute the subject of the present study. Nickel, iron and lanthanum were coated on calcium silicate filters via co-impregnation technique, and catalytic filters were characterized by ICP-MS, XPS, XRD, TEM, TGA, TPR and BET techniques. The influences of varying reaction temperature and addition of Fe or La to Ni-based catalytic filters on methane conversion, and hydrogen selectivity have been investigated in view of preliminary results obtained from reactions with 6% methane-nitrogen mixture, and catalytic filters were tested with model biogas mixtures at optimum reaction temperature of each filter which were 750 °C or 850 °C. Approximately 93% methane conversion was observed with nearly 6% methane-nitrogen mixture, and 97.5% methane conversion was obtained with model biogas containing CH₄ which is 6%, CO₂, CO, and N₂ at 750 °C. These results indicate that calcium silicate provides a suitable base material for catalytic filters for partial oxidation of methane and biogas containing methane.     

Ni/La2O3 catalysts for dry reforming of methane: Effect of La2O3 synthesis conditions on the structural properties and catalytic performances

10 wt%Ni/La₂O₃ catalysts for dry reforming of methane (DRM) were synthesized by wetness impregnation of lanthana supports prepared using sol-gel citric method with and without NH₃ addition (Ni–La CA-NH₃ and Ni–La CA, respectively). The support preparation conditions affect the nature, phase composition, and distribution of Ni phases (LaNiO₃, NiO and La₃Ni₂O₆). The gradient temperature DRM tests (400–800 °C) reveal higher catalytic activity of Ni–La CA (at 650 °C, X(CO₂) = 65.7%, X(CH₄) = 54.6%, H₂/CO = 0.71). The Ni–La CA-NH₃ shows higher stability (at 650 °C and 24 h, X(CO₂): 73.7% => 76.4%, X(CH₄): 64.7% => 64.6%, H₂/CO: 0.77 => 0.72). For both catalysts, La₂O₂CO₃ phase is formed after long run tests at 650 °C 24 h, with the greater TGA weight loss and stronger deactivation being observed for Ni–La CA. The H₂-reduced Ni La CA-NH₃ features ultrasmall (1–2 nm) Ni NPs strongly interacting with the support. Catalyst nature affects the amount of carbon coke formed.     

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.     

Hydrogen and/or syngas production by combined steam and dry reforming of methane on nickel catalysts

Two alumina supported Ni catalysts with pore sizes of 5.4 nm and 9 nm were synthetized, characterized and tested in the Combined Steam and Dry Reforming of Methane (CSDRM) for the production of hydrogen rich gases or syngas. The reaction mixture was designed to simulate the composition of real clean biogas, the addition of water being made in order to have molar ratios of H₂O:CO₂ corresponding to 2.5:1, 7.5:1 and 12.5:1. Structural and functional characterization of catalysts revealed that Ni/Al₂O₃ with larger pore size shows better characteristics: higher surface area, lower Ni crystallite sizes, higher proportion of stronger catalytic sites for hydrogen adsorption, and higher capacity to adsorb CO₂. At all studied temperatures, for a CH₄:CO₂:H₂O molar ratio of 1:0.48:1.2, a (H₂+CO) mixture with H₂:CO ratio around 2.5 is obtained. For the production of hydrogen rich gases, the optimum conditions are: CH₄:CO₂:H₂O = 1:0.48:6.1 and 600 °C. No catalyst deactivation was observed after 24 h time on stream for both studied catalysts, and no carbon deposition was revealed on the used catalysts surface regardless the reaction conditions.     

Biogas steam reformer for hydrogen production: Evaluation of the reformer prototype and catalysts

This work aims to investigate a biogas steam reforming prototype performance for hydrogen production by mass spectrometry and gas chromatography analyses of catalysts and products of the reform. It was found that 7.4% Ni/NiAl₂O₄/γ-Al₂O₃ with aluminate layer and 3.1% Ru/γ-Al₂O₃ were effective as catalysts, given that they showed high CH₄ conversion, CO and H₂ selectivity, resistance to carbon deposition, and low activity loss. The effect of CH₄:CO₂ ratio revealed that both catalysts have the same behavior. An increase in CO₂ concentration resulted in a decrease in H₂/CO ratio from 2.9 to 2.4 for the Ni catalyst at 850 °C, and from 3 to 2.4 for the Ru catalyst at 700 °C. In conclusion, optimal performance has been achieved in a CH₄:CO₂ ratio of 1.5:1. H₂ yield was 60% for both catalysts at their respective operating temperature. Prototype dimensions and catalysts preparation and characterization are also presented.     

Modification of silica supported nickel catalysts with lanthanum for stability improvement in methane reforming with CO2

Dry reforming of methane (DRM) with excessive methane composition at CH₄/CO₂ = 1.2:1 was studied over lanthanum modified silica supported nickel catalysts (Ni-xLa-SiO₂, x: 1, 2, 4, and 6% in the target weight percent of La). The catalysts were prepared by ammonia evaporation method. Nickel phyllosilicate and La₂O₃ were the main phases in calcined catalysts. The modification of La enhanced the formation of 1:1 and Tran-2:1 nickel-phyllosilicate. There existed an optimum content of La loading at 1.50 wt% in Ni–2La–SiO₂ which resulted in its highest reduction degree (95.3%). The catalysts with appropriate amounts of La exhibited higher amount of CO₂ adsorption and created more medium and strong base centers. The sufficient number of exposed metallic nickel sites to catalyze the reforming reaction, as well as enough medium and strong basic sites in Ni–La–SiO₂ interface to accomplish the carbon removal were two important factors to attenuate catalyst deactivation. The catalyst stability evaluated at 750 °C for 10 h followed the order: Ni–2La–SiO₂ > Ni–4La–SiO₂ > Ni–1La–SiO₂ ≈ Ni–6La–SiO₂ > Ni–SiO₂. Ni–2La–SiO₂ catalyst possessed the lowest deactivation behavior, whose CH₄ conversion dropped from 60.2 to 55.9% after 30 h operation at 750 °C, indicating its high resistance against carbon deposition and sintering.     

CO2 methanation over nanocrystalline Ni catalysts supported on mechanochemically synthesized Cr2O3-M (M=Fe,Co, La,and Mn) carriers

In the present study, a series of Cr₂O₃ powders modified by different promoters such as Fe, Co, La, and Mn were synthesized using a facile and solvent-free mechanochemical method and the prepared powders were used as a catalyst carrier for the preparation of 20 wt%Ni catalysts in CO₂ methanation. The results indicated that among all catalysts, the nickel catalyst supported on the Mn-promoted Cr₂O₃ exhibited the best catalytic performance. The results showed that there was an optimum for the Mn content and the increment in Mn content up to 15 wt% improved the catalytic performance due to its positive influence on increasing nickel dispersion and catalyst reducibility. The 20 wt%Ni/15 wt%Mn–Cr₂O₃ catalyst possessed a CO₂ conversion of 72.12% and CH₄ selectivity of 100% at 350 °C (H₂/CO₂ = 3 M ratio, GHSV = 18,000 ml/g_cat.h) with high stability during 12 h on stream. The obtained results showed that the increment in H₂/CO₂ molar, and the decrement in GHSV value and calcination temperature improved the catalytic performance.     

Exsolution of Ni nanoparticles on the surface of cerium and nickel co-doped lanthanum strontium titanate as a new anodic layer for DIR-SOFC. Anti-coking potential and H2S poisoning resistance of the prepared material

The aim of this study was to evaluate a new catalytic material for biogas-fuelled DIR-SOFCs. This material was a perovskite-type SrTiO₃ doped with La, Ce and Ni of a general formula La_0.27Sr_0.54Ce_0.09Ni_0.1Ti_0.9O_3-σ (LSCNT). Additional preparation steps were undertaken to promote a nickel exsolution process. Heat post-treatment of powders in a humidified H₂ resulted in an intensive growth of nickel nanoparticles (NPs) while the reduction temperature was increased gradually from 800 to 1200 °C. A selected reduction temperature equal to 900 °C gave the NPs an average size of 22 nm. The prepared material was used as a functional layer deposited onto the anodic site of a Ni/YSZ-supported SOFC to promote the effective reforming of synthetic and H₂S-contaminated biogas at 750 °C. It was found that after 130 h of operation in a 60% CH₄/40% CO₂ mixture, the fuel cell with an additional LSCNT layer showed higher power density, and no carbon deposits were observed. However, 20 ppm of H₂S present in the fuel caused a full deactivation of both the reference and SOFC with LSCNT layer. Cyclic tests in sour biogas revealed that the fabricated anodic layer is much more resistant to sulfur poisoning compared to a bare Ni/YSZ anode. Recovery of overall performance after 3 poisoning cycles was nearly 90% for the fuel cell with the LSCNT layer, while the unmodified one reached only 75%. The concentrations of the exhaust gases, such as CH₄, CO₂, and CO, were continuously measured in situ using a FTIR-based technique. A thermochemical analysis revealed that the investigated material ensured much better biogas reforming stability over the whole testing time and strongly promoted catalytic reactions.     

Bi-reforming of methane for hydrogen production using LaNiO3/CexZr1-xO2 as precursor material

In this work, the performance of Ni-based catalysts derived from LaNiO₃/Ce_xZr_1-xO₂ (x = 1, 0.75 and 0.50) for the bi-reforming of methane from biogas was studied. Furthermore, the catalysts were characterized by several techniques including in situ X-ray diffraction (in-situ XRD) and X-ray absorption near edge structure spectroscopy XANES at Ce L_III-edge and at Ni K-edge. It was shown that (i) all catalysts were reduced at temperatures below 700 °C and (ii) the addition of zirconium into cerium lattice improved the reducibility of the supports. Additionally, the catalytic test results showed that all supported catalysts initially exhibited a decrease in CH₄ and CO₂ conversions, which could be associated with possible oxidation of nickel particles. It has been proved that the precursor LaNiO₃/Ce_0.75Zr_0.25O₂ had the best performance since it presented the highest catalytic activity and good selectivity for hydrogen during the bi-reforming of methane at 800 °C.     

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.