Dry Reforming Reaction Research Articles

Physical and chemical characteristics and activity of nickel-modified cobalt-iron-containing catalysts in the reaction of dry reforming of methane

In the process of dry reforming of methane (DRM), the activity of low-percentage catalysts based on cobalt and iron oxides and their modification with nickel oxide was studied. It has been established that the addition of nickel oxide into the Fe2O3/γ-Al2O3 catalyst increases the degree of methane conversion from 14 to 89%, and also increases the yield of target reaction products H2 to 43.0 vol.%, CO to 46.1 vol.% at 850 °C. On a Co3О4-NiО/γ-Al2O3 catalyst at 850 °C, methane conversion reaches to 88.1%, the yield of H2 and CO is 44.8%. TPR-H2 analyzes showed that the introduction of nickel oxide into Fe2O3/γ-Al2O3 composition, in contrast to the Co3O4/γ-Al2O3 catalyst, the temperature peaks of Fe2O3-NiО/γ-Al2O3, reduction shift towards lower temperatures and weaken the interaction of metals with the support - γ-Al2O3 and thereby the amount of active reduced particles of iron and nickel oxides increases, which ensures good catalytic activity of Fe2O3-NiО/γ-Al2O3. According to the XRD results, spinel-like form - NiFe2O4, NiAl2O4 and CoAl2O4, also phase as Fe2O3 were obtained on the Fe2O3-NiО/γ-Al2O3 catalyst. This indicates that the developed catalysts form new phases that are active at high temperatures to produce synthesis gas in reduction-oxidation processes during the DRM reaction.

Response surface optimization of hydrogen-rich syngas production by methane dry reforming over bimetallic Mn-Ni/La2O3 catalyst in a fixed bed reactor

The present work utilizes a response surface optimization technique to optimize hydrogen-rich syngas production through the process of methane dry reforming (DRM). This optimization is achieved by employing a bimetallic Mn–Ni/La2O3 catalyst. The study aimed to evaluate the impact of three key parameters, namely reaction temperature, time on stream (TOS), and gas hourly space velocity (GHSV), on the hydrogen to carbon monoxide (H2/CO) ratio in syngas during the DRM. The Mn–Ni/La2O3 catalyst, synthesized using the sequential wet impregnation technique, exhibited suitable physicochemical properties necessary for DRM reaction, as evidenced by the obtained characterization data. Among the five models examined, it was found that the quadratic versus 2FI model substantially fit the experimental data, as evidenced by a p-value <0.05. The analysis of variance (ANOVA) conducted on the quadratic response surface model compared to the 2FI model demonstrated that both the reaction temperature and the TOS had a significant impact on the H2/CO ratio in the syngas. The only significant interaction factor was the relationship between the reaction temperature and the TOS. Under the specified optimal circumstances of 15 000 ml/g.h, 850 °C, and 258.15 min, an H2/CO ratio of 0.98 was achieved. The resulting H2/CO ratio of 0.98 is almost 1, indicating its suitability as a feedstock for methanol production in the Fischer-Tropsch synthesis (FTS).

Performance assessment of a novel porous catalytic reactor with a hydrogen-selective membrane for enhanced methane dry reforming process – CFD investigation

This manuscript offers a thorough examination of the efficiency of a reactor-assisted membrane system for the production of syngas through a process of methane dry reforming (DRM). The proposed strategy aims to bring attention to the optimization of the DRM and reverse water gas shift (RWGS) reactions, towards achieving increased conversions of methane and carbon dioxide, as well as increased purity in syngas production. This goal will be accomplished by integrating a selectively permeable membrane within the central region of the tubular catalytic porous bed reactor. The primary objective of the current research is to quantitatively assess the impact of operational parameters on both the hydrogen flux and concentration distribution of the various components residing in the reactor. This study highlights the impact of inlet feed pressure on hydrogen flux. It is found that an elevation in the inlet feed pressure from 1 to 4 bar yields an average increase in hydrogen flux from 2.60 to 4.21 kg/(m2.h), particularly when the inlet feed pressure is set at 2 bar. However, a subsequent increase to attain a pressure of 4 bar results in a decline in hydrogen flux to a rate of 2.78 kg/(m2.h). Moreover, increasing the inlet feed temperature from 900 to 1100 K leads to a substantial augmentation in the average hydrogen flux, from 7.08 to 8.56 kg/(m2.h), while maintaining a reactor wall temperature of 1000 K. As another finding, a molar ratio of CH4/CO2 of 1 leads to the greatest mean hydrogen flux of 4.73 kg/(m2.h) across the membrane interface. The current research work could provide useful tips/guidelines for efficient reactor design and optimization; it also enhances comprehension of reactor-assisted membrane systems in the context of syngas production.

Dry reforming of methane over Ni–Mg–Al and Ni–Ca–Al type hydrotalcite-like catalysts: effects of synthesis route and Ru incorporation

Abstract Ni-incorporated Mg–Al type hydrotalcite-like catalytic materials were synthesized following impregnation and co-precipitation routes, and their catalytic performances were compared in the dry-reforming reaction of methane. The effects of Ru impregnation on the catalytic performance of Ni-incorporated Mg–Al were also investigated. Results showed that the catalytic performance of the Ni-incorporated Mg–Al type catalyst (NiMgAlO), which was prepared by the co-precipitation route, was highly stable during dry-reforming reaction tests performed at 600 °C, extending up to 24 h. The fractional conversion of CO2 (0.42) was higher than the fractional conversion of CH4 (0.29) due to the contribution of the reverse water gas shift reaction. However, the contribution of the reverse water gas shift reaction to the product distribution was much less with the catalyst prepared following the impregnation route (Ni@MgAlO). This difference was shown to be mainly due to the state of the nickel in the catalyst structures. Ni-impregnated Ca–Al type hydrotalcite-like catalyst (Ni@CaAlO) was also synthesized and tested in dry reforming of methane. Results obtained with the Ni-impregnated Ca–Al type catalyst showed some changes in its structure and the formation of some CaCO3 during the dry reforming reaction. The comparison of the performances of Ni-impregnated Mg–Al and Ca–Al type catalysts showed a higher amount of coke on the surface of Ni@CaAlO than Ni@MgAlO. It was also concluded that significant coke minimization and highly stable catalytic performance could be achieved by the impregnation of 1 % Ru to the NiMgAlO catalyst. The amount of coke deposited on the catalyst decreased from about 30 % to less than 5 %, by Ru impregnation. The decrease of the surface area of the Ru-impregnated catalyst was also only about 3 % after 240 min of reaction time.

Dynamic trap of Ni at elevated temperature for yielding high-efficiency methane dry reforming catalyst

Highly dispersed and stable metal catalysts with small nanoparticles have received extensive attention in elevated-temperature thermocatalytic process. However, the available strategies to stabilize metal sites, by constructing defective structures on catalyst supports and developing controllable preparation steps at room temperature, show limited effect, because these active metal sites can be mobile and sintering at elevated temperature. Herein, dealuminated Beta zeolite with abundant surface defects of silanol nests is applied as support, then dynamic trap strategy and subsequent reduction process at elevated temperature is devoted to transfer Ni-based precursors into the silanol nests, thus obtaining small nanoparticles Ni catalysts that are suitable for high-temperature methane dry reforming (DRM). Some in-situ characterization processes and the ingenious designed experiments are performed to identify the dynamic trapping process. The rational fabricated catalysts exhibit high catalytic reactivity for DRM reaction in long-term operation.

Investigation into the coking-related key reaction steps in dry reforming of methane over NiMgOx catalyst

With pre-reduced NiMgOx catalyst, the structure evolution, catalytic performance, surface species and coking-related reaction steps are investigated in methane dry reforming (DRM) at selected temperatures. Satisfactory conversion of CH4 and CO2, H2/CO ratio, and anti-coke stability are achieved in long-term (78 h) reaction at 650 °C as a proper temperature. The characterizations evidence co-existence of metallic Ni0 and solid solution phases in the working catalysts. Combined catalytic evaluation and coke analysis reveal that, at 650 °C, endothermic CO2-free CH4 decomposition shows a high initial rate for H2 production but severe coke deposition for rapid deactivation, serving as the primary coking process. In contrast, exothermic CO disproportionation exhibits a lower reaction rate and a higher coke graphitization degree. The in-situ DRIFT spectra demonstrate that carbonates and bicarbonates serve as the primary adsorbates during CO2 dissociation process, whereas formate intermediates dominate in DRM reactions. Such evolution of the surface species verifies facile dissociation of both CH4 and CO2 in well-matched rates, promoting coke-resistance DRM reaction over NiMgOx catalyst.

Biogas dry reforming over nickel-silica sandwiched core–shell catalysts with various shell thicknesses

A series of nickel-silica sandwiched catalysts were synthesized to investigate the effect of shell thicknesses on the reaction of dry reforming. The thicknesses of the silica shell were adjusted by TEOS content and coating time of the silica shell. The outcomes exhibited that encapsulating the Ni-SiO2 catalyst by mesoporous silica shell effectively decreased carbon formation. Higher carbon resistance property of the nickel-silica sandwiched catalyst was related to the confined nickel particles by silica shell, which immobilizes metal particles, hampers the agglomeration and prevents uprooting Ni particles by the growing filamentous carbon. The results revealed that the amount of carbon deposition gradually decreased with the augment of TEOS content. The sandwiched catalyst with 2 ml TEOS exhibited high methane and CO2 conversions of 71.5% and 91.5% under CH4/CO2 = 1.5 and T = 700 °C for 20 h, respectively. Also, negligible carbon was observed on the surface of the catalyst and the original structure of the catalyst was well preserved after the stability test. The results revealed that with an increase in coating time, the catalytic activity improved and carbon deposition decreased.

Ultra-flexible Al2O3 fibers: A novel catalyst support material for sustainable catalysis

Flexible aluminum oxide (Al2O3) fibers were prepared by the blow spinning method and their potential as a high-temperature catalyst support was investigated. The synthesized Al2O3 fibers exhibited remarkable flexibility in both mechanical compression and recovery tests, which remained intact in a wide temperature range from −196 °C to 1200 °C. Moreover, their low thermal conductivity of 0.030 W K−1∙m−1, demonstrated an outstanding thermal insulation. Subsequently, nickel nanoparticles were uniformly distributed on the surface of the Al2O3 fibers as a self-supporting catalyst using a conventional impregnation method. The resulting self-supporting Ni/Al2O3 catalyst demonstrated remarkable thermo-catalytic performance and re-activation capability at high temperatures for thermocatalytic reaction of dry reforming of methane (DRM). Our findings highlight the potential of pure Al2O3 flexible fibers as a versatile material for various industrial applications, including high-temperature catalysis.

High-performance CoCe catalyst constructed by the glucose-assisted in-situ reduction for CH4/CO2 dry reforming

In this paper, the CoCe catalysts, which were prepared using a glucose-assisted in-situ reduction method, used to the CO2/CH4 dry reforming (DRM). The physicochemical properties of the prepared catalysts were investigated by H2-TPR, XRD, BET, Quasi in-situ XPS and CO2-TPD. The findings revealed that the metal Co was the primary active species in the DRM reaction. The good interaction between Ce and Co species can effectively promote the precursors to be reduced to form the active Co0 species and oxygen vacancies, which can also effectively inhibit the Co0 species to be sintered. The metal Co crystallinity and crystal size, active Co0 centers and oxygen vacancies can be successfully constructed by the glucose-assisted method. With the introduction of the glucose promoter, the crystal size of the corresponding catalyst metal Co decreased from 23.21 nm to 18.67 nm, the active Co0 species content on the catalyst surface increased from 41.3 % to 45.7 %, and the adsorbed oxygen content on the surface increased from 20.0 % to 23.0 %. Besides, the glucose promoter can affect the electronic effects of Co-Ce species to promote the DRM reaction. The CoCe3-G catalyst with a Co/Ce mole ratio of 3.0 exhibited the best reforming catalytic performances, and the CH4 and CO2 conversion was 87.2 % and 54.0 % at atmospheric pressure and 700 °C, respectively. Meanwhile, the CoCe3-G catalyst exhibited excellent reforming catalytic stability.

Effects of Operating Parameters and Feed Gas Compositions on the Dry Reforming of Methane over the Ni/Al2O3 Catalyst

The effects of operating parameters such as reaction temperature, space velocity, and feed gas composition on the performance of the methane dry-reforming reaction (DRM) over the Ni/Al2O3 catalyst are systemically investigated. The Ni/Al2O3 catalyst, which is synthesized by conventional wet impregnation, showed well-developed mesoporosity with well-dispersed Ni nanoparticles. CH4 and CO2 conversions over the Ni/Al2O3 catalyst are dramatically increased as both the reaction temperature is increased, and space velocity is decreased. The feed gas composition, especially the CO2/CH4 ratio, significantly influences the DRM performance, catalyst deactivation and the reaction behavior of side reactions. When the CO2-rich gas composition (CO2/CH4 &gt; 1) was used, a reverse water gas shift (RWGS) reaction significantly occurred, leading to the consumption of hydrogen produced from DRM. The CH4-rich gas composition (CO2/CH4 &lt; 1) induces severe carbon depositions followed by a reverse Boudouard reaction, resulting in catalytic activity drastically decreasing at the beginning followed by a stable conversion. The catalyst after the DRM reaction with a different feed ratio was analyzed to investigate the amount and structure of carbon deposited on the catalyst. In this study, we suggested that the optimal DRM reaction conditions can achieve stable performances in terms of conversion, hydrogen production and long-term stability.

Kinetics of Natural Kaolinite as a Catalyst for Toluene Dry Reforming

This study aims to develop a kinetic model for natural kaolinite as a potential tar removal catalyst in biomass gasification processes. The catalyst was crushed, sieved (0.2mm), and analyzed using TGA, BET, and XRF. The apparent first-order kinetic parameters of the dry reforming reaction at temperatures ranging from 750 to 900°C under 1atm were used to determine kaolinite's catalytic activity. It was found that both dry reforming and thermal cracking reactions occurred simultaneously. Furthermore, the raw kaolinite catalyst significantly removed toluene (80% at 900°C), at activation energy and frequency factor of 209 kJ/mol and 5.86×109s−1, respectively. Capitalizing on its catalytic activity in its natural form and its high efficacy as fluidized bed material, kaolinite can have great potential in primary and secondary tar reduction measures.

Porous CoCe composite catalyst prepared by hydrothermal assisted soft template method for CH4/CO2 dry reforming

The CoCex composite catalysts prepared by hydrothermal assisted template agent CTAB, have superior catalytic performances for CH4/CO2 dry reforming (DRM). The physicochemical properties of the catalysts were investigated in depth with the help of XRD, H2-TPR, CO2-TPD, ICP, Quasi in-situ XPS and N2 adsorption–desorption measurements. The transition metal Co is the main active center in the DRM reaction, which can easily release the outer electrons in the reaction to activate the reactant molecules. The introduction of Ce species can promote the highly dispersed metal Co species and catalytic active centers to be formed, as well as the adsorption and activation of CO2 molecules by the catalyst. Ce species can produce strong electronic effects with Co species, which can promote the electron-deficient CeO2-δ and electron-rich Coδ- species to be formed. The formation of CeO2-δ species facilitates the adsorption and activation of CO2 molecules, and the active oxygen species on the CeO2-δ surface facilitates the oxidative activation for CH4 molecules. The CH4 and CO2 reactant molecules can be adsorbed and activated by the formed Coδ- species to form CH4-x (x = 0–4) and CO2δ- reactive species, which can promote the DRM reaction. The Co/Ce molar ratio has an important effect on the physicochemical properties and CO2 adsorption performance of CoCex catalysts. And the CoCe2 catalyst prepared at a 2.0 Co/Ce molar ratio exhibited superior catalytic performance and high stability for the DRM reaction. The CH4 and CO2 conversion of the CoCe2 catalyst reached 88.6%, and 52.1% at 700 °C, respectively. In addition, the CoCe2 catalyst can maintain high cycle stability for CH4/CO2 dry reforming.

Sintering resistant cubic ceria yolk Ni phyllosilicate shell catalyst for methane dry reforming

Methane dry reforming (DRM) reaction is an efficient strategy to achieve carbon neutralization. Whereas, nano-catalysts, which are highly active due to size effect, are prone to sinter under the relatively high reaction temperature conditions, leading to the degradation of catalytic performance and accumulation of carbon. Therefore, preventing sintering is highly desired. In this manuscript, we synthesize cubic CeO2 yolk Ni phyllosilicate shell (CeO2 @Ni-Ps YS) catalyst which exhibits superb catalytic performance for DRM reaction. This is because the Ni bearing Ps structure mitigates the agglomeration of Ni nanoparticles due to strong metal support interaction (MSI); whilst CeO2 still preserves cubic morphology due to the protection by yolk shell structure, isolating CeO2 from each other. In addition, the yolk shell structure also provides intimate interaction between reactant gases and catalyst, which is known as confinement effect and further contributes to its better catalytic performance than the CeO2 @Ni-Ps CS catalyst. By comparison, serious sintering of both Ni and CeO2 occurs for DP Ni-Ps/CeO2 catalyst, leading to its continuous degradation of DRM performance. This method is promising to synthesize other efficient yolk shell catalysts for use in sustainable reaction processes.

Strong coke-resistivity of spherical hollow Ni/SiO2 catalysts with shell-confined high-content Ni nanoparticles for methane dry reforming with CO2

Hollow nanocatalysts, which are vehemently researched for their delimited cavity and enclosed shell, could manifest tunable focal properties besides well-defined active sites, thus enhancing the catalytic functionality. Herein, nickel-silicate hollow spheres (NHSs) with varied shell thickness and interior cavity size were commensurately designed. Distinction between various NHSs-derived Ni/SiO2 with identically mimicked morphologies was realized by examining their catalytic performance for methane dry reforming (DRM) reaction with sweeping pre- and post-reaction characterizations (TEM, XPS, XANES, in-situ DRIFTS). Besides facilitating the DRM reaction up to its thermodynamic limit, it was revealed that optimal NHS conformation is beneficial as a potential natural barrier against sintering and coking bottlenecks. Furthermore, a fine-tuned shell composition could endow improved Ni-sintering resistivity and enhanced reactivity to the NHS nanocatalysts. Our findings prove that the hollow interior space with a conducive shell thickness positively influences the reactant conversion and coking hindrance during the DRM reaction.

Highly coke-resistant Ni-La2O2CO3 catalyst with low Ni loading for dry reforming of methane with carbon dioxide

A series of xNi-La2O2CO3 catalysts with Ni loadings of 0.5–5 wt%, composed of Ni components supported on lanthanum oxycarbonate, were constructed via a simple wet impregnation method and systematically investigated for the reaction of dry reforming of methane with carbon dioxide to syngas (DRM). The xNi-La2O2CO3 catalyst with Ni loading lower than 1 wt% was primarily composed of well-defined Ni-La interfaces after reduction. However, xNi-La2O2CO3 with Ni loading of 2–5 wt% mainly possessed isolated Ni nanoparticles and Ni-La interfaces after reduction. The process of coke formation was proposed that carbon deposition was quickly occurring around the isolated active Ni sites, and then gradually evolved into carbon nanotubes encapsulating Ni nanoparticles, which were finally exsolved from the catalyst surface as the reaction proceeded. Interestingly, no coke formation was observed on the Ni-La interfaces after the DRM reaction even for 300 h. Therefore, the creation of catalytically active Ni-La interfaces indeed significantly improved the coke-resistant performance of the catalyst and was responsible for the much higher catalytic durability of 1Ni-La2O2CO3 than 5Ni-La2O2CO3. Moreover, the catalyst model and its activation of CH4 and CO2 in the DRM reaction were tentatively proposed based on the structure-performance relationship. The current study not only guides for potential industrial pathways for the DRM reactions but also provides a simple and effective method for the design of coke-resistant catalysts for other challenging reactions.

Enhanced syngas production from glycerol dry reforming over Ru promoted -Ni catalyst supported on extracted Al2O3

Crude glycerol, a by-product of biodiesel production, has drawn considerable attention to the importance of glycerol valorization through dry reforming reaction to obtain syngas. The selection of suitable catalysts is significantly important to enhance the catalytic activity in glycerol dry reforming (GDR) reactions. Hence, Ru with different loadings (i.e. 1%, 2%, 3%, 4%, 5%) doped in 15% Ni-extracted Al2O3(EA) was evaluated as catalyst via GDR process in this study. The catalyst prepared by ultrasonic-impregnation assisted technique was subjected to 8 h of CO2 reforming of glycerol. The reactant conversions and products yield was in the order of 3%Ru-15%Ni/EA > 5%Ru-15%Ni/EA > 4%Ru-15%Ni/EA > 2%Ru-15%Ni/EA > 1%Ru-15%Ni/EA > 15%Ni/EA, while the quantity of carbon deposited was in the order 15%Ni/EA > 1%Ru-15%Ni/EA > 2%Ru-15%Ni/EA > 4%Ru-15%Ni/EA > 5%Ru-15%Ni/EA > 3%Ru-15%Ni/EA. 3%Ru-15%Ni/EA attained the greatest glycerol conversions of 90%, H2 yield of 80% and CO yield of 72% with the lowest carbon deposition of 7.38%. The dispersion of Ni particles on EA support evidently improved after the promotion step with Ru, which minimized the agglomeration of Ni and smaller crystallite size. In addition, the introduction of Ru increased the oxygen storage capacity which significantly reduced the formation of carbon during the reaction. GDR's optimal reaction temperature obtained over 3%Ru-15%Ni/EA catalysts was at 1073 K (i.e. 93% glycerol conversion; 87% H2 yield; 79% CO yield). Over a 72 h time on stream at 1073 K, 3%Ru-15%Ni/EA catalyst had superior catalytic activity and stability. Overall, 3%Ru-15%Ni/EA catalyst was more coke-resistant than other promoted catalysts due to its accessible structure, higher oxygen storage capacity, moderate basicity, uniformly dispersed Ni phase and stronger Ru/Ni-EA interaction.

Synthesis gas production by dry reforming of methane over Neodymium-modified hydrotalcite-derived nickel catalysts

Neodymium-modified hydrotalcite-derived nickel catalysts (NixNdMgAlO) by adjusting the Nd content (x) at a range of 2.5–10% were synthesized via co-precipitation method. The catalytic properties of these catalysts were evaluated in the reaction of dry reforming of methane (DRM) at 750 °C. The initial CH4 conversion decreased with the order of Ni7.5NdMgAlO > Ni5NdMgAlO > NiMgAlO > Ni2.5NdMgAlO > Ni10NdMgAlO. The Ni7.5NdMgAlO catalyst with a compromised proportion of Nd at 7.5% had the smallest nickel crystallite size (8.1 nm), highest metal dispersion (11.8%), the highest exposed active sites on the surface (6.3 m2/g) as well as the relatively intimate interaction between small Ni2+ species and the support. Moreover, Ni7.5NdMgAlO with the largest amount of CO2 desorption (736.6 μmol/g-cat) effectively oxidized the coke on the catalyst surface, and manifested the excellent coke resistance (2.4%) in addition to the highest CH4 and CO2 conversion in the DRM reaction. In addition, the optimal addition (7.5%) of Nd to NiMgAlO resulted in a lowering of the activation energy of CO2 by 15%. At excessive Nd content, Ni10NdMgAlO exhibited larger nickel crystallite size (10.5 nm) and was subject to severe accumulation of encapsulating carbon leading to pronounced deactivation.

Integration of dry-reforming and sorption-enhanced water gas shift reactions for the efficient production of high-purity hydrogen from anthropogenic greenhouse gases

With growing interest in the bulk production of the alternative energy carrier hydrogen, dry-reforming of methane using carbon dioxide has attracted great interest as one of the possible carbon capture and utilization (CCU) technologies and hydrogen production methods. An integrated system combining the dry-reforming and water gas shift reactions is suggested to improve the productivity of hydrogen, and a system has also been developed for high-purity hydrogen production from a single system using the sorption-enhanced reaction concept. To realize the proposed system, we develop the Ru-doped Sr0.92Y0.08TiO3 perovskite catalysts and investigate their characteristics using various analyses. The prepared catalysts exhibit excellent CH4 conversion of 92.2% for the dry-reforming reactions at 800 °C without performance degradation by coke formation. Moreover, high-purity hydrogen (>99.5%) is directly produced by the proposed integrated system using anthropogenic greenhouse gases as reactants, and the efficiency is further enhanced by recycling the captured CO2 to the dry-reforming reactor.

Unveiling the Role of Active Oxygen Species in Oxidative Dehydrogenation of Ethane with CO2 over NiFe/CeO2

AbstractThe oxidative dehydrogenation of ethane (ODH) assisted by CO2 to produce ethylene is inevitably accompanied by the side reaction of dry reforming (DRE) to produce carbon monoxide. However, the key factor determining the dehydrogenation selectivity is still ambiguous. In this paper, four different NiFe/CeO2 catalysts were synthesized via an impregnation method over four types of CeO2. The dehydrogenation selectivity of the four catalysts ranged from 40 % to 83 %. Temperature‐programmed surface reaction and transient response experiments reveal the existence of two types of oxygen species over NiFe/CeO2 catalysts. FeOx layers exist as an oxygen species supply buffer over CeO2 supports. Weakly electrophilic oxygen species supplied by FeOx overlayers could participate in producing C2H4 while strong electrophilic oxygen species supplied by CeO2 supports could participate in producing CO. The content of weakly electrophilic oxygen species is identified to be a rational descriptor of C2H4 selectivity.

Alumina Support for Cobalt Catalyst in a Methane Dry Reforming Reaction: The Role of Water Content in a Solvent Medium

This study aimed to synthesize alumina from an inorganic aluminum nitrate precursor in various binary solvent systems of ethanol and water using the sol-gel self-assembly (SSA) method, employing a triblock copolymer, pluronic P123, as the pore-directing agent. The resulting materials were implemented as a support for the cobalt (Co) catalyst in a methane dry reforming (MDR) reaction at 1073 K under 1 atm. Regardless of the water percentage used in the support synthesis, the methane dry reforming reaction over Co catalysts on alumina supports showed the negligible change in conversion during the 12 h reaction. Moreover, there was evidence of large quantities of amorphous carbon and graphitic carbon on the spent catalyst surface. However, the low oxidation temperature of these deposited carbons could help maintain the balance between the carbon formation and the carbon elimination processes on the catalyst surface during the reforming reaction, hence prolonging the lifetime of the catalyst. The high conversion of methane (CH4) from 64.6% to 82.8% and carbon dioxide (CO2) from 70.7% to 86.6% for the MDR reaction over the as-prepared alumina-supported Co catalyst demonstrated a significant improvement in catalyst production for the MDR reaction from the viewpoint of large-scale applications.