Syngas production from methane dry reforming over Ni/SBA-15 catalyst: Effect of operating parameters

The influence of operating conditions including reactant partial pressure and reaction temperature on the catalytic performance of 10%Ni/SBA-15 catalyst for methane dry reforming (MDR) reaction has been investigated in this study. MDR reaction was carried out under atmospheric pressure at varying CH₄/CO₂ volume ratios of 3:1 to 1:3 and 923–1023 K in a tubular fixed-bed reactor. SBA-15 supported Ni catalyst exhibited high specific surface area of 444.96 m² g^?1 and NiO phase with average crystallite size of 27 nm was detected on catalyst surface by X-ray diffraction and Raman measurements. H₂ temperature-programmed reaction shows that NiO particles were reduced to metallic Ni⁰ phase with degree of reduction of about 90.1% and the reduction temperature depended on the extent of metal-support interaction and confinement effect of mesoporous silica support. Catalytic activity appeared to be stable for 4 h on-stream at 973–1023 K whilst a slight drop in activity was observed at 923 K probably due to deposited carbon formed by thermodynamically favored CH₄ decomposition reaction. Both CH₄ and CO₂ conversions increased with rising reaction temperature and reaching about 91% and 94%, respectively at 1023 K with CO₂ and CH₄ partial pressure of 20 kPa. CH₄ conversion improved with increasing CO₂ partial pressure, ${\mathit{P}}_{\mathit{C}{\mathit{O}}_{\mathit{2}}}$ and exhibited an optimum at ${\mathit{P}}_{\mathit{C}{\mathit{O}}_{\mathit{2}}}$ of 30–50 kPa depending on reaction temperature whilst a substantial decline in CO₂ conversion was observed with growing ${\mathit{P}}_{\mathit{C}{\mathit{O}}_{\mathit{2}}}$. Additionally, CH₄ and CO₂ conversions decreased significantly with rising CH₄ partial pressure because of increasing carbon formation rate via CH₄ cracking in CH₄-rich feed. Post-reaction characterization shows that active Ni metal phase was not re-oxidized to inactive metal oxide during MDR reaction. The heterogeneous nature of deposited carbons including carbon nanofilament and graphite was detected on catalyst surface by Raman measurement.     

Methane bi-reforming over boron-doped Ni/SBA-15 catalyst: Longevity evaluation

A highly active and stable boron-promoted catalyst was successfully prepared by using the sequential incipient wetness impregnation technique and examined for methane bi-reforming reaction. The initial investigation found that the NiO and B₂O₃ particles were dispersed on the outer surface of the high surface area SBA-15 support. In addition, the catalytic activity was increased linearly with the tested reaction temperature due to the endothermic nature of the reaction. In fact, the catalyst achieved the CH₄ conversion and H₂/CO molar ratio of approximately 67.3% and 2.7, respectively at 1073 K. The resulting product ratio is highly suitable for downstream Fischer-Tropsch (FT) synthesis. The B-promoted catalyst showed the lowest degree of catalyst deactivation (4%) at 1023 K. Additionally, the XPS measurements unveiled that the boron facilitates the adsorption of CO₂ by donating electrons to the neighbouring Ni cluster and thus improved its catalytic performance. Furthermore, Raman and XRD analysis revealed that the boron promotion on 10%Ni/SBA-15 could prevent the reoxidation and deposition of carbonaceous species.     

Optimal Ni loading towards efficient CH4 production from H2 and CO2 over Ni supported onto fibrous SBA-15

The transformation of SBA-15 into fibrous type SBA-15 (F-SBA-15) as well as the influence of Ni loadings (1, 3, 5, and 10 wt%) towards an efficient CH₄ production from H₂ and CO₂ were explored. The synthesized catalysts were characterized using XRD, BET, ICP-MS, FTIR, FESEM-EDX, TEM, and in-situ FTIR adsorbed pyrrole. Increasing Ni loadings onto F-SBA-15 support promoted excellent performance towards CO₂ methanation. The efficacy in CO₂ methanation over Ni/F-SBA-15 increased with a sequence of 1%Ni/F-SBA-15 < 3%Ni/F-SBA-15 < 5%Ni/F-SBA-15 ≈ 10%Ni/F-SBA-15, indicating the superior performance and stability of 5%Ni/F-SBA-15. The increasing trend was due to the fibrous morphology of support which enhanced the quantity of SiONi bond, triggered better Ni dispersion, strengthen metal-support interaction, and increased the basicity. However, higher Ni loadings (10 wt%) onto F-SBA-15 slightly declined the performance and stability of CO₂ methanation due to the limited spaces for substitution of Ni species with the silanol groups of F-SBA-15 upon the bulk Ni phase, poorer Ni dispersion, weaker metal-support interaction, and lower basicity. The new finding of combination between fibrous SBA-15 (F-SBA-15) with an optimum Ni loading contributed towards an outstanding performance and thus could be applied in various applications.     

Optimization of hydrogen production from steam reforming of biomass tar over Ni/dolomite/La2O3 catalysts

Industrially, the endothermic process of steam reforming is carried out at the lowest temperature, steam to carbon (S/C) ratio, and gas hourly space velocity (GHSV) for maximum hydrogen (H₂) production. In this study, a three-level three factorial Box-Behnken Design (BBD) of Response Surface Methodology (RSM) was applied to investigate the optimization of H₂ production from steam reforming of gasified biomass tar over Ni/dolomite/La₂O₃ (NiDLa) catalysts. Consequently, reduced quadratic regression models were developed to fit the experimental data adequately. The effects of the independent variables (temperature, S/C ratio, and GHSV) on the responses (carbon conversion to gas and H₂ yield) were examined. The results indicated that reaction temperature was the most significant factor affecting both responses. Ultimately, the optimum conditions predicted by RSM were 775 °C, S/C molar ratio of 1.02, and GHSV of 14,648 h⁻¹, resulting in 99 mol% of carbon conversion to gas and 82 mol% of H₂ yield.     

Bi-reforming of methane on Ni/SBA-15 catalyst for syngas production: Influence of feed composition

Bi-reforming of methane (BRM) was evaluated for Ni catalyst dispersed on SBA-15 support prepared by hydrothermal technique. BRM reactions were conducted under atmospheric condition with varying reactant partial pressure in the range of 10–45 kPa and 1073 K in fixed-bed reactor. The ordered hexagonal mesoporous SBA-15 support possessing large specific surface area of 669.5 m² g^?1 was well preserved with NiO addition during incipient wetness impregnation. Additionally, NiO species with mean crystallite dimension of 14.5 nm were randomly distributed over SBA-15 support surface and inside its mesoporous channels. Thus, these particles were reduced at various temperatures depending on different degrees of metal-support interaction. At stoichiometric condition and 1073 K, CH₄ and CO₂ conversions were about 61.6% and 58.9%, respectively whilst H₂/CO ratio of 2.14 slightly superior to theoretical value for BRM would suggest the predominance of methane steam reforming. H₂ and CO yields were significantly enhanced with increasing CO₂/(CH₄ + H₂O) ratio due to growing CO₂ gasification rate of partially dehydrogenated species from CH₄ decomposition. Additionally, a considerable decline of H₂ to CO ratio from 2.14 to 1.83 was detected with reducing H₂O/(CH₄ + CO₂) ratio due to dominant reverse water-gas shift side reaction at H₂O-deficient feedstock. Interestingly, 10%Ni/SBA-15 catalyst was resistant to graphitic carbon formation in the co-occurrence of H₂O and CO₂ oxidizing agents and the mesoporous catalyst structure was still maintained after BRM. A strong correlation between formation of carbonaceous species and catalytic activity was observed.     

Hydrogen production via CO2 reforming of CH4 over low-cost Ni/SBA-15 from silica-rich palm oil fuel ash (POFA) waste

H₂ was produced via CO₂ reforming of CH₄ (CRM) using low-cost Ni/SBA-15 synthesized from palm oil fuel ash (POFA) waste as silica precursor. A series of Ni/SBA-15 were synthesized by employing different Na₂SiO₃-POFA/P123 mass ratios (2.0, 2.9 and 4.0) and were compared with Ni/SBA-15 prepared from commercial Na₂SiO₃ (Ni/SBA-15(Comm.)). Na₂SiO₃-POFA/P123 = 2.9 was found to be the optimal synthesis ratio, which produces a well-defined hexagonal framework, smaller NiO particles, stronger Ni-support interaction, homogeneous metal distribution and higher amount of basic sites. The catalytic performance complied with the trend of Ni/SBA-15(R4.0) < Ni/SBA-15(R2.0) < Ni/SBA-15(R2.9) ≈ Ni/SBA-15(Comm.), indicating the excellent catalytic activity of Ni/SBA-15(R2.9) (H₂ selectivity = 87.6%). The favorable physicochemical properties of Ni/SBA-15(R2.9) ameliorated the active Ni metals stabilization over SBA-15 and boosted the catalyst's virtues towards an outstanding catalytic performance. Hence, it is affirmed that POFA with an optimal Na₂SiO₃-POFA/P123 ratio of 2.9 can be served as silica substitution of Ni/SBA-15 for efficient H₂ production via CRM.     

Boron-doped Ni/SBA-15 catalysts with enhanced coke resistance and catalytic performance for dry reforming of methane

Nickel-based heterogeneous catalysts have shown promising results in many industrial-scale catalytic reforming processes and hydrocarbon reforming reactions such as dry reforming of methane (DRM). However, it is also reported that Ni-based catalysts generally show less resistance to the carbonaceous deposition, which ultimately causes their rapid deactivation during the reaction. One possible solution to improve the coke resistance is the addition of a promoter to the catalyst, which has shown successful results to reduce the coke formation. Therefore, this study also aimed to prepare boron-promoted Ni-based catalysts and investigate their efficiency for DRM reactions. A series of different catalysts with 10% nickel and x% boron (x: 1%, 2%, 3%, and 5%) were prepared by using an ordered mesoporous silica as a support and tested in DRM. The results demonstrated that boron-promoted Ni/SBA-15 catalysts obtained significant catalytic activity for CH₄ and CO₂ conversions. Meanwhile, it was noticed that a lower concentration of boron (1 and 2%) was more favourable to achieve higher catalytic activity, whereas the higher concentration (3% and 5%) resulted in a comparatively lower conversion for CH₄ and CO₂. Evidently, the higher activity of 2% B-promoted catalyst was ascribed to the synergistic effect of high surface area and lower crystallite size that greatly improved the active sites accessibility. Moreover, the results confirmed 14% carbon deposition on unpromoted (NS) catalyst and it was reduced to 1.3% for 2% boron-promoted catalyst owing to the presence of B-OH species on catalyst surface.     

Titanium nitride promoted Ni-based SBA-15 catalyst for dry reforming of methane

Titanium nitride (TiN) promoted nickel catalysts were synthesized and employed as an alternative catalyst in dry reforming of methane (DRM). The series of this catalyst containing various amount of Ni and TiN was prepared in two steps, direct synthesis of SBA-15 in the presence of TiN and the impregnation of Ni. The influence of Ni and TiN loading on DRM reaction was investigated using a feed ratio of CH₄/CO₂ = 1, at 700 °C and atmospheric pressure for a duration of 4 h. The promising catalysts, that gave the highest feed conversions and product yields, were selected for further investigation, compared to non-promoted Ni catalyst using the same conditions but for 12 h of reaction. The results showed that the performance of Ni catalyst was improved by the incorporation of TiN. The modified catalysts provided not only high catalytic activity but also enhancement of coke resistance.     

The reconstruction of Ni particles on SBA-15 by thermal activation for dry reforming of methane with excellent resistant to carbon deposition

The improved Ni/SBA-15 catalysts were prepared by thermal inducing method and applied to dry reforming of methane. The promoting effect exerted by thermal activated reconstruction was studied systematically by means of various characterization techniques. TEM results indicated that the thermal inducing process led to the reconstruction of Ni particles to form ultra-fine Ni nanoparticles (2–3 nm) uniformly distributed on SBA-15. The resulting Ni nanoparticles not only improved catalytic activity but also inhibited the formation of carbon deposition during the DRM reaction. The thermal treatment catalyst with tiny particles presented the superior catalytic performance in the DRM reaction, where H₂/CO ratio was close to 1 and no deactivation was discovered after continuous reaction at 750 °C for 50 h. Additionally, it was found that the metal-support interaction was strengthened observably after the thermal activated reconstruction. The strong interaction anchored Ni particles to prevent their high temperature sintering, thus forming stable catalytic centers. Therefore, the conversions of both CO₂ and CH₄ almost stabilized at 90% and 85%, respectively, for the thermal activated reconstruction samples during the long-term catalytic test.     

SBA-15 supported mesoporous Ni and Co catalysts with high coke resistance for dry reforming of methane

In this study, the activity of the mesoporous SBA-15 supported Ni, Co and NiCo catalysts prepared by the wet-impregnation were investigated in dry reforming of methane reaction. The catalysts were characterized by XRD, TPR, N₂ adsorption-desorption isotherms, SEM, TEM and TG/DT techniques before and/or after activity tests. N₂ adsorption-desorption isotherm of the all catalysts were consistent with Type IV isotherm, indicating mesoporous structures. TEM images of bimetallic NiCo catalysts clearly proved the presence of characteristic honeycomb structure. Incorporation Co into SBA-15 supported Ni catalysts inhibited the agglomeration of the nickel particles due to the formation of NiCo alloy. Activity test results showed that bimetallic 4Ni1Co@SBA-15 catalyst (Ni/Co:4/1) gave highly promising activity with high methane (73%) and carbon dioxide (89%) conversion values at 750 °C. Co incorporation into SBA-15 supported Ni catalyst significantly decreased the coke formation during dry reforming of methane.     

Enhanced dry reforming of methane over mesostructured fibrous Ni/MFI zeolite: Influence of preparation methods

Dry reforming of methane is acknowledged to be an environmentally benign route for conversion of CO₂ and CH₄ into syngas (CO and H₂). Herein, unique mesostructured fibrous MFI support was synthesized by microemulsion method, and Ni incorporation via double solvent, physical mixing and wetness impregnation methods. Results revealed wetness impregnation catalyst had the highest activity and stability. Activation energy of reactants showed a reliance on acidity, where moderate acidity impeded deactivation by CH₄ cracking. Furthermore, degree of catalyst deactivation was negligible compared to what is attainable on conventional zeolite catalysts. Thus, fibrous morphology, microscopic dispersion and moderate acidity played a positive role in boosting reactants accessibility to active Ni sites which results in preservation of activity under the harsh conditions of DRM process.     

Catalytic activity of SBA-15 supported Ni catalyst in CH4 dry reforming: Effect of Al,Zr, and Ti co-impregnation and Al incorporation to SBA-15

In this study, the catalytic activity of the mesoporous SBA-15 supported Ni–Al, Ni–Zr, and Ni–Ti catalysts prepared by an impregnation method were investigated in dry reforming of methane. In addition, Al incorporated SBA-15 (Al–SBA-15) materials used as catalyst support were synthesized following a one-pot hydrothermal route in three different conditions: synthesis in the presence of only HCl, only NaCl, and both HCl and NaCl (denoted as A, S, and B, respectively). All catalysts were characterized by XRD, N₂ adsorption-desorption isotherms, ICP-OES, DRIFTS, SEM, TEM-EDX and TGA techniques before and/or after reaction tests. Among Al, Zr, and Ti impregnated catalysts, Ni–Al impregnated catalyst showed the highest activity in dry reforming of methane. According to activity test results, Al–SBA-15 supported Ni catalyst prepared by the one-pot hydrothermal route in the presence of both HCl and NaCl showed the best catalytic activity with high methane (81%) and carbon dioxide conversion (88%) values at 750 °C. The highest H₂ and CO selectivity values were obtained with the same catalyst with an H₂/CO molar ratio of 0.80. Therefore, these results showed that partial Al (0.11%) incorporated into the structure of SBA-15 was sufficient to improve the catalytic activity of the catalyst in dry reforming of methane.     

Structural effect of Ni/SBA-15 by Zr promoter for H2 production via methane dry reforming

5 wt% of Ni/SBA-15 supported with numerous Zr loading (1–7 wt%) were produced using sol-gel technique at 60 °C. The influence of Zr promoter on the physiochemical properties of Ni/SBA-15 catalysts for methane dry reforming were examined in a fixed-bed reactor at 800 °C. Analytical characterizations including XRD, BET, FTIR, N₂ adsorption desorption, TEM and TGA were conducted to study the physiochemical properties of Zr/Ni/SBA-15 catalysts for the sake of identification of the amount of coke deposition formed on the spent catalyst. Increasing the amount of Zr loading from 1 to 7 wt% supported on Ni/SBA-15 reduced the catalyst's surface area as was proven from the physiochemical properties of Zr/Ni/SBA-15 catalyst. The catalytic activity test revealed that the optimum Zr loading was 1 wt% at which CH₄ and CO₂ conversions were 87.07% and 4.01%, meanwhile H₂:CO ratios was 0.42. This result was owing to the existence of the Zr species in promoting a good dispersion of Nickel (Ni) active sites on the catalyst surface as affirmed from XRD and FTIR results. The latest discovery indicates that promotion of 1 wt% Zr onto Ni/SBA-15 can prompt excellent catalytic performance in CRM.     

CO2 reforming of methane over Ni/ZnAl2O4 catalysts: Influence of Ce addition on activity and stability

The catalytic performance of Ni supported on Ce-promoted ZnAl₂O₄ was evaluated in methane dry reforming. The effect of different nominal loadings of cerium (3, 5 and 7 wt%) in the activity, product yield and stability was studied. Ce presented a promote effect in catalytic activity, product yield and especially in stability. However the catalytic performance was considerably influenced by the amount of cerium. SEM images presented smaller particles and TPR profiles revealed stronger active phase/support interaction by Ce addition which led to increasing methane conversion and decreasing coke deposition. Although high amount of Ce was not in favor of its promoting effect due to aggregation of CeO₂ on the catalyst surface. Among the catalysts investigated, the optimal catalytic activity and stability was achieved over the sample with 5 wt% of cerium.     

Dry reforming of methane for hydrogen production over NiCo catalysts: Effect of NbZr promoters

Ni/Al₂O₃, NiCo/Al₂O₃MgO and NiCo/Al₂O₃MgO/NbZr nanocatalysts were prepared by the sol-gel technique with citric acid and tested in the dry reforming of methane (DRM). In this paper, the effects of Nb and Zr addition as promoters in Al₂O₃MgO supported catalysts on the physicochemical characteristics and the reaction performance in the DRM were investigated. The NbZr promoters are expected to enhance the activity and performance of the catalyst due to its high thermal stability and also improvement in the metal dispersion of the catalyst. The catalysts samples were characterized by FESEM, BET, XRD, TEM, H₂-TPR and CO₂-TPD techniques. FESEM results demonstrated that NiCo/Al₂O₃MgO/NbZr has more uniform and well-dispersion of metal than NiCo/Al₂O₃MgO. The BET results unravel that the addition of NbZr promoters increase the surface area of the synthesized catalyst due to the high surface area of the promoters. There is a formation of MgAl₂O₄ spinel-type solid solution proved by the XRD and CO₂-TPD analysis due to the interaction between alumina lattice and magnesium metal which has high resistance to carbon formation. The DRM reaction is performed in the tubular furnace reactor at 1073.15 K, 1 atm and a CH₄/CO₂ ratio of unity. The sol-gelled NiCo/Al₂O₃MgO/NbZr was found to be the most proper choice for DRM which illustrates much higher conversion (86.96% for CH₄ conversion and 87.84% for CO₂ conversion) compared to the other catalysts. This is due to the strong interaction between active metals and supports, resistance to coke formation and higher stability in DRM reaction.     

Process optimization of DBD plasma dry reforming of methane over Ni/La2O3MgAl2O4 using multiple response surface methodology

In this study, 10% Ni/La₂O₃MgAl₂O₄ nano-flake catalyst was synthesized, characterized and tested in a catalytic dielectric barrier discharge (DBD) plasma for dry reforming of methane (DRM). With design of experiment (DoE), the influence of process parameters namely (1) total feed flow rate (ml min⁻¹), (2) feed ratio (CO₂/CH₄), (3) input power (W) and (4) catalyst loading (g) were examined using multiple response surface methodology (RSM) through a four-factor, five-level central composite design (CCD). Second-order regression models were applied for evaluating the interaction between the process parameters and responses. Input power (X₃) and total feed flow rate (X₁) were the two most influential process parameters followed by catalyst loading (X₄) and feed ratio (X₂). The experimental and predicted results from the optimum conditions fitted-well with less than ±5% margin of error. The possible dynamic interactions between the process variables were elucidated. The optimum values are feed flow rate = 18.8 ml min⁻¹, feed ratio = 1.05, input power = 125.6 W and catalyst loading = 0.6 g. At these conditions, the predicted CH₄ and CO₂ conversions are 79.86% and 84.03%, respectively. The H₂ and CO yields are predicted as 41.37% and 40.47%, respectively while H₂/CO ratio is above unity. The calculated EE from the RSM model is predicted as 0.135 mmol kJ⁻¹. Low carbon deposition observed on the spent catalyst is attributed to the highly basic and oxidative nature of the La₂O₃ co-supported catalyst.     

Optimization of hydrogen production by photocatalytic steam methane reforming over lanthanum modified Titanium (IV) oxide using response surface methodology

In this study, the optimization of hydrogen production by photocatalytic steam methane reforming over Lanthanum modified TiO₂ has been investigated using response surface methodology. The La/TiO₂ photocatalysts were synthesized using wet impregnation method and characterized for physicochemical and photocatalytic properties by N₂ physisorption, X-ray powder diffraction (XRD), Scanning electron microscopy (SEM), Energy dispersive X-ray (EDX), and ultraviolet-visible (UV-vis) spectroscopy. The characterization shows that the La/TiO₂ possesses appropriate properties to be used as photocatalysts. The photocatalysts were employed in the optimization studies of hydrogen production by photocatalytic steam methane reforming. The effects of irradiation time (10–150 min), metal loading (1–3%), methane concentration (10–50%), and steam concentration (0.5–1.5%) on the rate of hydrogen production were determined employing Box-Behnken experimental design. The application of the RSM resulted in the formulation of four models out which the quadratic model was adjudged to adequately fit the experimental data. A further statistical analysis of the quadratic model established the significance of the model with p-value far less than 0.05 and coefficient of determination (R²) of 0.975. A non-significant lack of fit obtained for the model further confirm the suitability of the quadratic model in fitting the experimental data. At the desirability function of 1, optimum conditions of 146.15 min, 2.94%, 22.83% and 1.24% for irradiation time, metal loading, methane concentration, and steam concentration, respectively resulted in the production of 2.42 μmol of hydrogen/min.     

Syngas production from dry reforming of methane over ni/perlite catalysts: Effect of zirconia and ceria impregnation

Ni catalysts with nominal loadings ranging between 2.5 and 20 wt% were synthesized over perlite by wet impregnation, then filtered, washed and calcined at 500 °C. Chemical analyses performed by MP-AES revealed that the maximum Ni content loaded over perlite corresponded to ～15 wt%. Therefore, for comparison reasons, a Ni(20 wt%)/perlite catalyst was prepared by wetness impregnation without performing any washing treatment. The so prepared catalysts were tested in methane dry reforming without performing any pre-treatment reduction. The catalytic performances were compared by increasing the temperature from 500 up to 800 °C under the reaction mixture composed of 15 vol% CH₄ + 15 vol% CO₂/N₂. Ni(15 wt%)/perlite was the most active catalyst among the series of monometallic samples. The effect of co-impregnating perlite with Ni and Zr or Ni and Ce precursors in order to obtain catalysts with final composition, Ni(15 wt%), 10 and 20 wt% as Zr or Ce, perlite (75 or 65 wt%) was, then, investigated. Characterizations performed by XRD, BET, DRS and H₂-TPR evidenced that the physico-chemical and reduction properties are influenced by the Ni content and by the presence of zirconia and ceria oxides. It is worth of noting the increased reducibility of NiO species promoted by zirconia and ceria addition. The catalytic activity in the dry reforming of methane was also affected by the presence of doping oxides, in terms of enhanced CH₄ and CO₂ conversions and higher H₂/CO atomic ratios. Runs tests at 700 °C for 12 h were carried out and the spent catalysts were analysed by TGA and TEM. Over Ni(15 wt%)/perlite large amount of amorphous carbon grows on the surface blocking the active centres, while zirconia and ceria doping improved the resistance to carbon poisoning favouring growing of filamentous carbon residues in small amount.     

Catalytic steam reforming of methane,methanol, and ethanol over Ni/YSZ: The possible use of these fuels in internal reforming SOFC

This study investigated the possible use of methane, methanol, and ethanol with steam as a direct feed to Ni/YSZ anode of a direct internal reforming Solid Oxide Fuel Cell (DIR-SOFC). It was found that methane with appropriate steam content can be directly fed to Ni/YSZ anode without the problem of carbon formation, while methanol can also be introduced at a temperature as high as 1000 °C. In contrast, ethanol cannot be used as the direct fuel for DIR-SOFC operation even at high steam content and high operating temperature due to the easy degradation of Ni/YSZ by carbon deposition. From the steam reforming of ethanol over Ni/YSZ, significant amounts of ethane and ethylene were present in the product gas due to the incomplete reforming of ethanol. These formations are the major reason for the high rate of carbon formation as these components act as very strong promoters for carbon formation.