Dry Reforming Of Methane Reaction Research Articles

Review and Outlook of Confined Ni Catalysts for the Dry Reforming of Methane Reaction

Review and Outlook of Confined Ni Catalysts for the Dry Reforming of Methane Reaction

Hydrothermally synthesized tremella-like monometallic Ni/SiO2 for effective and stable dry reforming of methane (DRM) to syngas

Despite its activity, monometallic Ni-catalyst is highly susceptible to coke deposition and sintering in catalyzing dry reforming of methane (DRM). To counter these, a novel tremella-like monometallic Ni/SiO2 catalyst was hydrothermally synthesized herein, realizing excellent activity, outstanding coke inhibition and robust structural stability for a durable DRM reaction. Functionality-speaking, the tapered ends of Ni-petals, sized at 8–15 nm, permit high DRM activity with suppressed coke formation while its thicker base spatially prevents Ni-sintering during high temperature reaction. Meanwhile, the open structure of catalyst resulting from such tremella-like structure also enhances the diffusion of reactants/products gas to/from catalytic surface, thus augmenting its activity for DRM. With merely 5 wt% Ni incorporated, CO2 and CH4 conversions of ∼90% could be attained with only ∼15% activity drop after 75 h of DRM. Full-restoration of activity could facilely be attained using 90 min in-situ oxidative regeneration. Mechanistic study coupling sorptive investigation, ex-situ XRD, and SEM reveals the pronounced adsorption tendency of CH4 over those of CO2, H2 and CO, confirming the adherence of DRM to Eley-Rideal reaction model in current study. Significantly, this study provides a new morphological-controlled strategy to conveniently impart excellent coke-inhibiting and sintering-resisting capability to monometallic Ni-catalyst.

Role of promoter on the catalytic activity of novel hollow bimetallic Ni–Co/Al2O3 catalyst in the dry reforming of methane process: Optimization using response surface methodology

In this research, the effect of promoter addition and its type on the catalytic performance and morphology properties of bimetallic Ni–Co catalysts on the novel hollow Al2O3 support was investigated in the dry reforming of methane (DRM) process. The response surface method (RSM) based on the optimal custom model was employed for maximizing CH4 and CO2 conversions, as well as H2 and CO yield. Four independent variables including Co to Ni mass ratio (0, 0.5, 1), DRM temperature (600, 650, 700 °C), CH4/CO2 molar ratio (1, 1.5, 2), and catalyst type (without promoter, with Mg or Y promoter) were selected for this purpose. Among three suggested optimized catalysts by the design expert, the yttrium-promoted one with 1 Co/Ni mass ratio (1Ni–Co–Y/Al) depicted the highest CH4 conversion of 86.50 %, CO2 conversion of 92.00 %, H2 yield of 85.11 %, and CO yield of 93.54 % at lower temperature of 679 °C and equal CH4/CO2 mole ratio of 1. The structural characterizations confirmed that the high activity of 1Ni–Co–Y/Al could be due to the better dispersed active sites and higher surface area of this catalyst compared with un-promoted and Mg-promoted samples. The time-on-stream performance of optimized catalysts at their optimized conditions was also compared experimentally, results of which showed more stability and activity of the Y-promoted sample during 12 h DRM reaction. The TGA, EDX, XRD, FESEM, and N2 physisorption techniques demonstrated the lower structural change and deposited carbon on the 1Ni–Co–Y/Al surface after reaction, which may be because of higher oxygen storage capacity (OSC) of this catalyst.

Investigating Ni nanoparticles on CeO2 for methane dissociation: a comparative study of theoretical calculations and experimental insights.

CeO2 supported with Ni nanoparticles has emerged as a promising catalyst for enhancing the efficiency of dry reforming of methane (DRM) reaction. Methane dissociation (CH4 → CH3 + H) was reported as one of the rate-determining steps in the DRM reaction. We elucidated the reaction mechanism and explored methods for reducing the activation energy using density functional theory (DFT) calculations, where the activation energy of methane dissociation was determined at multiple Ni4 cluster sites on CeO2. In parallel, we experimentally evaluated methane dissociation based on the methane consumption rate in the DRM reaction using newly developed flower-like Ni-supported CeO2 catalyst (Ce(F)). The experimental activation energy was determined to be 0.69 eV (15.91 kcal mol-1), closely matching the DFT-calculated value of 0.80 eV (18.45 kcal mol-1) for the Ni4 cluster model, validating our theoretical predictions. Additionally, we discovered that positively charging the Ni4 can lower the activation energy of methane dissociation. These findings contribute to a deeper understanding of how to control the activation energy of the methane dissociation reaction in DRM.

Active Ni-Titanate Nanostructures for Dry Reforming of Methane

One of the main causes of climate change is the increased concentration of greenhouse gases from anthropogenic sources. Therefore, the search for processes that provide mitigation of these gases is imperative and very important. Dry reforming of methane (DRM) is a process that converts CO2 and CH4 in pure syngas. Thus, this study aims to evaluate the influence of the calcination temperature (500 and 700 °C) in the titanate nanotubes (TNT) structure. The calcination at 700 °C led to a new morphology in the form of titanate nanorods (TNR). TNT and TNR nanostructures were modified with Ni and used as catalysts in the DRM reaction. The CO2 and CH4 conversions were around 60 and 48%, respectively, when using Ni-TNT500 at 700 ºC, while values around 85 and 70%, respectively, were obtained using TNR in the same reactional condition. Both catalysts presented values of H2/CO ratio near 1.

Accelerating active catalyst discovery: a probabilistic prediction-based screening methodology with applications in dry reforming of methane

Dry reforming of methane (DRM) is a promising technology for syngas production from CH4 and CO2. However, discovering feasible and efficient catalysts remains challenging despite recent advancements in machine learning. Herein, we present a novel probabilistic prediction-based, high-throughput screening methodology that demonstrates outstanding performance, with a coefficient of determination (R2) of 0.936 and root-mean-square error (RMSE) of 6.66. Additionally, experimental validation was performed using 20 distinct catalysts to ensure the accurate verification of the model, 17 of which were previously unreported combinations. Our model accurately predicts CH4 conversion rates and probability values by considering catalyst design, pretreatment, and operating variables, providing reliable insights into catalyst performance. The proposed probabilistic prediction-based screening methodology, which we introduce for the first time in the field of catalysis, holds significant potential for accelerating the discovery of catalysts for DRM reactions and expanding their application scope in other crucial industrial processes. Thus, the methodology effectively addresses a key challenge in the development of active catalysts for energy and environmental research.

Influence of organic ligand and nickel loading on the performance of MOF-derived catalysts for dry reforming of methane

MOF-derived Ni-based catalysts were synthesized via a one-pot solvothermal method for this work. This research studied the effects of two organic ligands on the properties, activity, and performance of the catalysts for dry reforming of methane (DRM). Also, the effect of nickel loading and DRM reaction temperature on the performance of the catalysts were analyzed. Nickel loading varied at 5%, 40%, and 100% and reaction temperatures of 500, 600, 700, and 800 °C were studied. Results obtained proved that the use of trimesic acid as the organic ligand produced more stable catalysts due to a smaller and better dispersed particle size, on a larger surface area caused by longer chain length, with minimal amount of coke formed. Also, the catalyst containing 100% nickel showed considerably good conversions of CH4 and CO2, and better stability with the use of trimesic organic ligand. However, the addition of CeO2 helped the performance of the catalyst due to the availability of surface oxygen which participated in oxidation reaction with the coke formed, further aiding the mitigation of coke. Interestingly, at a reaction temperature of 500 °C, the MOF-derived catalyst remained stable, despite lower conversion rates. The stability was improved by using MOFs as templates for catalysts.

Effects of preparation methods on the size and interface of Ni–W bimetallic catalysts for dry reforming of methane

One of the most effective methods of utilizing CH4 and CO2 resources is the dry reforming of methane (DRM). However, the small particle size and the metal-support interactions of Ni–W bimetallic catalysts are key factors affecting activity and carbon deposition. This article evaluates the effect of Ni–W bimetallic catalysts synthesized by different preparation methods on their catalytic performance in DRM reactions. The results show that the bimetallic catalyst prepared by the solid-state grinding method exhibits excellent catalytic performance and anti-carbon deposition performance. The conversion rate of CH4 and CO2 remain unchanged during 1450 min, which is 58% and 66%, respectively. Through various characterization methods, it has been proven that the bimetallic catalyst prepared by the solid-state grinding method effectively reduces the size of Ni particles and increases the number of exposed active sites. In addition, this method also enhances the metal-support interactions, which helps to improve the stability of the catalyst.

Cs promoted Ni/ZrO2-Al2O3 catalysts for dry reforming of methane: Promotional effects of Cs for enhanced catalytic activity and stability

Carbon Capture and Utilization (CCU) technologies offer a promising avenue for transforming captured CO2 into valuable products, serving as renewable fuels or precursors for high-value synthesis. This study explores the dry reforming of methane (DRM) as a viable pathway to convert captured CO2 and CH4 into syngas, achieving high equilibrium conversion through the use of suitable catalysts. Conventional nickel-based catalysts are susceptible to carbon deposition, necessitating innovative approaches to enhance their performance. A tubular microreactor was employed to conduct the reforming process at 800 °C, utilizing Cs-promoted Ni catalysts supported on 90 % Al2O3 and 10 % ZrO2-based support composition. Catalyst preparation involved the impregnation technique, and subsequent characterization employed N2-physisorption, XRD, H2-TPR, TGA, TPD, and Raman spectroscopy. The DRM reaction was systematically investigated using the Ni/ ZrO2- Al2O3 catalysts, with a specific focus on the catalytic effects of Cs promotion. Observations revealed that Cs incorporation onto the ZrO2- Al2O3 matrix led to a substantial increase in hydrogen yield and selectivity across all catalyst compositions, accompanied by a significant reduction in carbon deposition on the catalyst surface. The optimal Cs loading, determined to be 3 wt% over Ni/ ZrO2- Al2O3 catalyst, exhibited CO2 and CH4 conversions of 90 % and 87 %, respectively, with an H2/CO yield approaching 1 (0.95). This research underscores the potential of Cs-modified catalysts in enhancing the efficiency of DRM for CCU applications, providing valuable insights into optimizing catalyst formulations for improved performance in carbon transformation processes.

A DFT study of elementary reaction steps of dry reforming of methane catalyzed by Ni: Explaining the difference between Ni particles supported on CeO2 and MnO[formula omitted]-doped CeO2

With the aid of DFT calculations, we investigate the elementary reaction steps of dry reforming of methane (DRM) on Ni(111) and NiO(100) as simple models of metallic and oxidized Ni catalysts. The reaction-path calculations reveal that DRM is feasible on metallic Ni at elevated temperatures. However, a notable problem with metallic Ni catalysts is the coke formation because the activation barrier for the C* formation is not considerably higher than those of the competing reactions that lead to the DRM products. In contrast, NiO does not encounter issues with coke formation, but it is not an effective catalyst due to too high activation energies and slow surface diffusion of H*. We also explain the experimentally observed difference between the DRM catalysts consisting of Ni particles supported on undoped and MnOx-doped CeO2 supports (designated as Ni/CeO2 and Ni/MnxCeO2, respectively). Specifically, we explain the absence of the 2020 cm−1 vibrational peak on the Ni/MnxCeO2 catalyst. Calculations univocally attribute the experimentally observed 2020 cm−1 peak to CO adsorbed on a top site of metallic Ni because all other sites and involved species display considerably different frequencies. The CO stretching frequency increases as Ni oxidizes, and on NiO(100), it is similar to the vibration of CO on the CeO2(111) support, about 2100 cm−1. Current results thus provide a sound explanation of why Ni/MnxCeO2 is a superior DRM catalyst to Ni/CeO2. In particular, the presence of the 2020 cm−1 peak on the Ni/CeO2 catalyst signals that Ni particles are sufficiently metallic and thus susceptible to carbon poisoning. In contrast, the absence of the 2020 cm−1 peak on the Ni/MnxCeO2 catalyst indicates that Ni particles are oxidized, i.e., the Ni oxidation is low enough to allow the DRM reaction but high enough to reduce the catalyst’s carbon poisoning.

Syngas production via dry reforming of methane over Ni/MgO-ZrO2 catalyst

This study intended to evaluate the catalytic activity of Ni/MgO-ZrO2 to produce syngas through dry reforming of methane (DRM). The catalyst was prepared by using co-precipitation method followed by impregnation of Ni metal. XRD, BET and FESEM were used to analyze the physicochemical characteristics of the prepared catalyst. A stainless steel vertical reactor fixed with a catalyst bed inside was used to run the DRM process at 800°C, 1 atm and 1:1:1 ratio of CO2:CH4:N2. From the three catalysts studied, Ni/MgO-15%ZrO2 had the maximum conversion for CH4 and CO2 compared to the other two catalysts. The high conversion achieved was because of zirconium oxide. The result obtained from the DRM reaction was further supported by the characterization results, which included average particle size, the morphology of the catalyst, and catalyst peaks.

Operando induced strong metal-support interaction of Rh/CeO2 catalyst in dry reforming of methane

Strong metal-support interaction (SMSI) is an important concept in heterogeneous catalysis that has a profound effect on the structure and activity of the supported metal catalyst. However, the catalyst with an uncontrolled SMSI state significantly prevents the accessibility of metal surface to reactants by encapsulation process which inevitably limits their practical application. Herein, we demonstrate that under the reaction condition of dry reforming of methane (DRM), the occurrence of SMSI (CO2-SMSI) can be operando induced between Rh and CeO2 which significantly improves the catalytic activity in DRM reaction. Detailed study has revealed that the formation of suitable Rhδ+/Rh0 species in CO2-SMSI is critical in improving CH4 activation, while the presence of permeable encapsulation layer is helpful to provide more active sites. This discovery provides a new approach to overcome the limitation of classical SMSI catalyst in DRM reaction.

Catalytic Performance of Bimetallic Cobalt–Nickel/Graphene Oxide for Carbon Dioxide Reforming of Methane

The design of economical and robust catalysts is a substantial challenge for the dry reforming of methane (DRM). Monometallic nickel-based catalysts used for DRM reactions had comparable activity to noble metals. However, they turned out to be less stable during the reactions. As a continuation of the interest in synthesizing catalysts for DRM, this paper evaluates the catalytic performance of bimetallic Co–Ni catalysts regarding their synergy effect, with graphene oxide (GO) as support for the first time. The synthesized bimetallic catalysts prepared via the wet-impregnation method were characterized using N2 physisorption analysis, scanning electron microscopy (SEM), thermogravimetric analysis (TGA), and X-ray diffraction (XRD). The catalytic test was performed in a stainless-steel tubular reactor in atmospheric conditions with a reaction temperature of 800 °C, time-on-stream (TOS) of 300 min and CH4: CO2 being fed with a ratio of 1:1. The bimetallic 10 wt%Co–10 wt%Ni/GO and 20 wt%Co–10 wt%Ni/GO catalysts had a similar BET specific surface area in N2 physisorption analysis. The XRD pattern displayed a homogeneous distribution of the Co and Ni on the GO support, which was further validated through SEM–EDX. The conversion of CO2, CH4, and H2 yield decreased with reaction time due to the massive occurrence of side reactions. High conversions for CO2 and CH4 were 94.26% and 95.24%, respectively, attained by the bimetallic 20 wt%Co–10 wt%Ni/GO catalyst after 300 min TOS, meaning it displayed the best performance in terms of activity among all the tested catalysts.

Ni, Co & Cu substituted CeO2: A catalyst that improves H2/CO ratio in the dry reforming of methane

This study focusses on developing a efficient heterogenous catalyst using a comparative approach of substituted and supported metal oxides. In this article two types of catalysts were prepared (I)Tri metal supported catalysts (NiCoCu/CeO2) and (II)-Trimetal substituted catalysts (Ce0.85Ni0.05Co0.05Cu0.05O2). The combination of transition-metal as Trimetal substituted catalyst is unique and novel and has not been explored earlier. The aim is to choose the right material which qualifies to be a potential DRM catalyst. The idea of comparing supported and substituted catalysts is to prove that substitution is indeed beneficial even though the surface may not have very high metal concentration. So, where the activity comes from? The activity comes from the activated oxygen which is generated on the surface as a result of the substitution. This activated oxygen is missing in the supported catalyst. In substitutional catalyst, the metals are substituted in the bulk while in the supported system the metals are confined to the surface. Both supported and substituted catalysts exhibit distinct differences in the dry reforming of methane (DRM) reaction. The NiCoCu substituted CeO2 exhibited high stability and activity under DRM reaction. Thermal gravimetric analysis (TGA) and transmission electron microscopy (TEM) explained that low amount of amorphous and graphitic carbon was deposited during the reaction in the substituted catalyst which is also removable easily. In comparison NiCoCu supported CeO2 catalyst is less reactive and less stable because carbon removal propensity is not good on the surface. Further investigation using the transient studies confirms the stability of the substituted catalyst is due to the ease of the reactions; C + OL → CO and CO2 + C → 2CO. The prevalence of methane decomposition step and the reactivity of the surface lattice oxygen (OL) is an essential tool to dictates the H2/CO ratio and the catalytic stability. Novelty of this work is in elucidating the exact role of surface oxygen in imparting the activity and stability to the DRM catalyst. This work also elucidates process mechanism for DRM in NiCoCu substituted CeO2 based on the transient reactivity of the catalyst. Our findings have significant implications in rationalizing the approach for the development of more efficient and effective DRM catalysts based on the principle of lattice oxygen.

Ni-Fe/La2O3 bimetallic catalysts for methane dry reforming: Elucidating the role of Fe for improving coke resistance

Dry reforming of methane (DRM) offers an effective approach for converting two cheap undesired greenhouse gases into valuable chemical feedstock of syngas. In this work, with the objective to obtain high efficiency Ni-based catalyst with superior coke resistance, a series of 6Ni-xFe/La2O3 catalysts were prepared by co-impregnation method, and were applied to DRM reaction. Effects of Fe doping, support contents, Ni dispersion on DRM performance of 6Ni-xFe/La2O3 catalysts were investigated. X-ray diffraction analysis and STEM-EDS mapping revealed that Ni-Fe alloy particles were well formed in the fresh reduced 6Ni-xFe/La2O3 catalysts. H2-TPR results showed that the addition of Fe can enhance the interaction between and Ni active sites and La2O3 support. In-situ Raman and TGA-DSC results demonstrated that the amount of La2O2CO3 species increased rapidly during DRM stability test on the spent Ni/La2O3 catalyst, leading to an obvious accumulation of carbon deposits. With the promotion by Fe, the reaction between the La2O2CO3 species and carbonaceous deposits can be accelerated, which results in more active and stable catalysts with significantly improved coking resistance. In addition, more oxygen vacancies could be obtained on Ni/La2O3 catalyst by Fe doping, as evidenced by the XPS results. It was concluded that these were the major reasons accounting for the significantly improved coke resistance for the 6Ni-xFe/La2O3 catalysts.

Response surface optimization of hydrogen-rich syngas production by the catalytic valorization of greenhouse gases (CH4 and CO2) over Sr-promoted Ni/SBA-15 catalyst

Dry reforming of methane (DRM) which utilizes CO2 and CH4, is a more efficient and environmentally friendly syngas production method. However, since the technique is endothermic, catalyst deactivation from sintering and carbon deposition has prevented its industrial implementation. This study investigated the effect of Strontium (Sr) promoter on Ni-based catalyst synthesized on SBA-15 support via the impregnation method. The incorporation of Sr as a promoter has demonstrated distinct advantages, primarily attributed to its remarkable capability to inhibit carbon formation. This property imparts a notable enhancement in the stability of the catalyst, thereby extending its operational lifespan and maintaining consistent catalytic performance. The physicochemical properties of the fresh catalyst were observed by using various characterization techniques such as X-Ray diffraction (XRD) analysis, N2 physisorption analysis, field emission scanning electron microscopy (FESEM), and temperature programmed reduction using hydrogen as the probing gas (TPR-H2). The catalysts were tested in DRM reaction using a tubular fixed bed reactor at 800 °C with an equimolar feed ratio. Overall, 1% Sr promoted Ni/SBA-15 showed enhanced performance having CO2 and CH4 initial conversions of 88.5% and 96.5%, respectively while remaining stable for 320 min on stream. Furthermore, the predicted optimal condition was 713.73 °C and a feed gas ratio (CH4:CO2) of 1.12, with CO2 and CH4 conversion rates of 69.59% and 84.83%, respectively, resulting in an H2:CO ratio of 1.00. Slight differences from the predicted values were considered insignificant, validating the Srb catalyst at a 95% confidence level with a 5% likelihood of error in the RSM model.

Theoretical study of the mechanism of dry reforming of methane over Pd-doped CeO2 supported-Ru catalyst: The importance of oxygen self-spillover behavior

Carbon deposition negatively affects the dry reforming of methane (DRM). Thus, here, palladium (Pd) was doped to Ru/CeO2 to enhance the oxygen self-spillover behavior on the interface, and the obtained effects were studied using the density functional theory (DFT) and microkinetic modeling. After doping Pd, the lattice oxygen was active. To simulate conditions closer to those of an experiment, a dynamic model under realistic conditions and a static model were considered. For the dynamic model, lattice oxygen atoms spilled over from the surface to the Ru spontaneously. DFT calculations demonstrated that interfacial oxygen self-spillover plays a pivotal role in increasing C-O formation and enhancing the DRM reaction rate while inhibiting the rapid decomposition of CHx, which hinders C* formation. Coke formation analysis indicated that oxygen spillover inhibits the coupling of C*-C* (C*+C*→C2*), leading to strong resistance to coke deposition and preventing the deactivation of catalysts. Microkinetic simulations showed that the dynamic model has a higher turnover frequency (TOF) rate and a higher selectivity for the DRM reaction. The high catalytic activity of the dynamic model is mainly due to the low coverage by CH*/C* on the catalyst’s surface. We expect that our results will provide a strategy for the design of DRM catalysts by enhancing interfacial oxygen self-spillover, using doped atoms.

CO2Fix: An approach to assess CO2 fixation potential of CCU reaction pathways

In this work we present a simple, yet powerful, metric for estimating the potential of a CCU reaction pathway to fix CO2. The CO2Fix metric is determined by using a model that accounts for various process variables and parameters that influence the ability of the reaction to convert CO2 in addition to its propensity to produce CO2 through the energy requirements of the process. The CO2Fix metric in this work accounts only for the direct CO2 emissions and indirect CO2 emissions related to the reaction portion of a CCU process. We demonstrate the use of the model to estimate the CO2Fix in two case studies representing common CCU reactions: dry reforming of methane (DRM) and CO2 hydrogenation to methanol. When using natural gas-powered energy, and under the same process assumptions, the CO2Fix was estimated to be 1.1 and 3.9 for the DRM and CO2 hydrogenation reactions respectively.

Recent Advances in Ni-Based Catalysts for CH4-CO2 Reforming (2013–2023)

In recent years, the greenhouse effect has emerged as a major environmental concern. As a result, the utilization and capture of greenhouse gases have become urgent tasks. The dry reforming of methane (DRM) reaction is a technology that directly converts greenhouse gases (CH4 and CO2) into valuable products. Ni-based catalysts have gained significant attention and industrial prospects in DRM reactions due to their excellent performance and cost-effectiveness compared to noble metals. However, challenges such as metal sintering and carbon deposition hinder its industrialization. This paper provides a review of the recent advancements in catalyst design for DRM reactions, with a focus on the impact of additives, supports, and preparation methods on Ni-based catalysts. It also describes the reaction and deactivation mechanisms, as well as the thermodynamics and kinetics of DRM reactions. Furthermore, this paper envisions the main challenges and opportunities associated with Ni-based catalysts in DRM research.

Enhanced catalytic stability and structural evolution of Rh-BN interface in dry reforming of methane under intensified CO2 partial pressure

Strong metal-support interaction (SMSI) is a crucial factor that determines the structure and performance of a supported metal catalyst. Herein, the SMSI effect of Rh nanoparticle catalyst supported on h-BN is investigated in the dry reforming of methane (DRM) reactions with different CO2/CH4 ratios. The catalyst characterization results demonstrate that the SMSI effect allows the Rh nanoparticles to be encapsulated by BOx overlayers under DRM reaction conditions (CO2/CH4 = 1/1), which prevents the interaction between the reactants and metal centers for causing rapid deactivation. By increasing the partial pressure of CO2 (CO2/CH4 = 3/1), Rh/BN exhibits significantly enhanced activity and long-term stability in the DRM reaction. CO2 or H2O in the reactive atmosphere can effectively etch the BOx overlayers for steadily exposing the active Rh-BN interface sites, as evidenced by the characterization. This observation extends the understanding of the SMSI effect at the interfaces between metal and non-oxide support.