Dry Reforming Of Methane Process Research Articles

Long-term stable catalyst for dry reforming of Methane: Ni-Nanocluster embedded in silica

Dry reforming of methane (DRM) is a fascinating catalysis to convert greenhouse gases into valuable syngas; however, the catalyst deactivation due to coking and sintering has posed a significant obstacle to practical use. Here, we introduce a novel synthetic approach for creating Ni nanoclusters (∼2 nm) embedded inside silica (NiES), without using any catalytic metal promoters. Compared to conventional Ni-SiO₂ catalysts, the NiES catalyst could fully utilize unique Ni-O-Si bonding within a bimodal silica matrix. This leads to exceptional reactivity and long-term stability for DRM without noticeable deactivation over 500 h of operations. Notably, characterizations revealed that Ni nanoclusters maintained their particle size even after this extended operation, significantly contributing to their resistance against carbon coking. These Ni clusters appeared to efficiently promote CH4 decomposition, while the continuously regenerated OH groups from dissociative adsorption of CO2 assisted in oxidizing carbon species. This study will substantially contribute to the swift implementation of the catalytic DRM process.

Design of a novel tubular membrane reactor with a middle annular injector for enhancement of dry reforming towards high hydrogen purity: CFD analysis

This study introduces a novel design of a tubular porous membrane catalytic reactor (TPMCR) with a middle annular injector, which aims to improve the performance of a dry reforming of methane (DRM) process. A computational fluid dynamics (CFD) model is developed for a fundamental configuration and subsequently verified using experimental data. The validated CFD model is utilized to examine the influence of different parameters, such as feed composition, inlet gas temperature and pressure, and injection rate, on the reactor performance. The study findings reveal that the introduction of a secondary gas during the injection process has the potential to regulate the process and positively affect the production rates of hydrogen and carbon monoxide. The optimal inlet temperature to attain the highest rate of hydrogen production is determined to be 900 K. The hydrogen selectivity is found to increase from 0.96 to 1.60 with the injection of pure steam when the injection rate is increased from 50 to 500 kg/(m2.s). In addition, the carbon monoxide selectivity is decreased from 6.30 to 2.67. The implementation of a middle annular injector within the proposed TPMCR design offers the potential for enhancing the efficiency and sustainability of chemical reactors. Consequently, the introduced modification leads to more efficient and environmentally friendly chemical processes, specifically in the realms of syngas and hydrogen production through the DRM process, resulting in improved purity levels.

Catalytic performance of NixCoy catalysts supported on honeycomb-lantern-like CeO2 for dry reforming of methane: Synergistic effect and kinetic study

Dry reforming of methane (DRM) is considered one of the most efficient methods for carbon utilization, as it can transform greenhouse gases (CH4 and CO2) into syngas (CO and H2) which could be widely used in the production of high-value hydrocarbons. The synergistic effect between Ni and Co is leveraged to enhance the coke resistance and stability of Ni-based catalyst during the DRM process, building upon the surface spatial confinement provided by honeycomb-lantern-like CeO2 support. The enhanced catalytic performance of Ni0.9Co0.1 catalyst can be attributed primarily to the addition of cobalt, which facilitates CO2 adsorption and activation, further promotes the Boudouard reaction and aids in the elimination of coke. This phenomenon is supported by evidence from CO2-TPD, XPS, SEM, TGA, XRD, and CO2-TPO analyses. Furthermore, the kinetics of Ni0.9Co0.1 are examined using Power-Law (PL) and Langmuir-Hinshelwood (LH) mechanisms, obtaining the explicit equations for the rate constants (k and kr), reaction orders of the reactants (α and β), and adsorption equilibrium constants (KCH4 and KCO2). The comparison of the predicted CH4 consumption rates with the experimental rates suggests that the LH mechanism is notably more precise than PL mechanism for Ni0.9Co0.1 catalyst. Moreover, the relevant kinetic parameters (the activation energy and pre-exponential factor), pertinent to coke gasification process for the spent Ni0.9Co0.1 and Ni1.0, are determined and calculated through CO2-TPO characterization and the modified Wigner-Polanyi equation.

An entropy engineering strategy to design sulfur-resistant catalysts for dry reforming of methane

The real-world conditions for dry reforming of methane (DRM) inevitably involve the presence of sulfur-containing compounds. Therefore, a general principle for designing sulfur-resistant catalysts is highly desired for the DRM process. In this work, driven by lower Gibbs free energy via entropy engineering, the high-entropy NiAl2O4-type catalyst {(Ni3MoCoZn)Al15Ox} is synthesized by a mechanochemical ball milling process. The DRM performance of the high-entropy catalyst was tested before and after being sulfided by SO2, and compared with those of the control catalysts. Various techniques such as XPS, HAADF-STEM, SO2-TPD, TGA-DSC, FTIR, and DFT theoretical calculations are utilized to reveal the mechanism of sulfur resistance in the high-entropy catalyst. The results indicate that the formation of crystalline high-entropy oxides in the (Ni3MoCoZn)Al15Ox, with its relatively higher configurational entropy, protects itself from SO2 poisoning. This contributes to superior SO2 tolerance compared to the control (Ni3)Al18Ox, and thus offers better DRM stability than the control binary, ternary, or quaternary catalysts after pre-sulfurization. The key essence of sulfur resistance lies in the lower adsorption energy of SO2 on the high-entropy catalyst. This high-entropy stabilization towards an anti-sulfur strategy may inspire the design and development of sulfur-resistant catalysts for catalytic applications in the near future.

A DFT study for in-situ CO2 utilization realized by calcium-looping dry reforming of methane based on Ni/CaCO3

The calcium-looping dry reforming of methane (CaL-DRM) process couples CO2 capture and dry reforming of methane process using Ni/CaO dual-functional material. This process in-situ converts CO2 captured by CaO through reacting with CH4, catalyzed by Ni, to produce syngas. However, researches on reaction mechanism for CaL-DRM are rare. In this work, the fundamental reaction mechanism of calcium-looping dry reforming of methane is elucidated by density functional theory (DFT) analysis. The energy barriers for elementary reactions involved in various potential pathways were investigated to determine the primary reaction pathway. The DFT analysis shows two possible reaction pathways for the CaL-DRM, with the CH* assisted CaCO3 dissociation pathway being the more favorable one. Along this pathway, CH4 undergoes three dehydrogenation steps to form CH*. Then, CH* reacts with the CaCO3* to produce CHO* and CaCO2*, accompanying the cleavage of one C-O bond in the carbonate. Afterwards, CHO* dissociates into CO* and H*. Finally, another C-O bond in CaCO2* breaks, generating CO* and CaO. Notably, CH4 reduces the energy barrier for CaCO3 dissociation from 3.47 to 2.733 eV. Moreover, the perturbation of electron clouds around O in CaCO3* in the presence of CH or C, as evidenced in electron density differential results, highlights the effective activation of C-O bond by CH or C, thereby promoting CaCO3 decomposition. This work provides further support for the potential mechanism for in-situ CO2 utilization achieved through CaL-DRM.

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.

Hydrogen production from dry reforming of methane, using CO2 previously chemisorbed in the Li6Zn1-xNixO4 solid solution

Li6ZnO4 was chemically modified by nickel addition, in order to develop different compositions of the solid solution Li6Zn1-xNixO4. These materials were evaluated bifunctionally; analyzing their CO2 capture performances, as well as on their catalytic properties for H2 production via dry reforming of methane (DRM). The crystal structures of Li6Zn1-xNixO4 solid solution samples were determined through X-ray diffraction, which confirmed the integration of nickel ions up to a concentration around 20 mol%, meanwhile beyond this value, a secondary phase was detected. These results were supported by XPS and TEM analyses. Then, dynamic and isothermal thermogravimetric analyses of CO2 capture revealed that Li6Zn1-xNixO4 solid solution samples exhibited good CO2 chemisorption efficiencies, similarly to the pristine Li6ZnO4 chemisorption trends observed. Moreover, a kinetic analysis of CO2 isothermal chemisorptions, using the Avrami-Erofeev model, evidenced an increment of the constant rates as a function of the Ni content. Since Ni2+ ions incorporation did not reduce the CO2 capture efficiency and kinetics, the catalytic properties of these materials were evaluated in the DRM process. Results demonstrated that nickel ions favored hydrogen (H2) production over the pristine Li6ZnO4 phase, despite a second H2 production reaction was determined, methane decomposition. Thereby, Li6Zn1-xNixO4 ceramics can be employed as bifunctional materials.

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.

A simulation model for ruthenium-catalyzed dry reforming of methane (DRM) at different temperatures and gas compositions

Dry reforming of methane (DRM) is an environmentally friendly technology for producing syngas while consuming CO2. However, the short lifespan of catalysts due to metal sintering, coke deposition, and sulfur poisoning hinders its widespread adoption. To address such issues, perovskite catalysts, which have shown superior performance and resistance to coke formation and poisoning, were developed. In this study, a comprehensive simulation model of a DRM reactor that employs Sr0·92Y0·08Ti0·95Ru0·05O3-d (SYTRu5) using COMSOL Multiphysics software was developed. The objective of this study is to contribute to the understanding of the intricate dynamics of DRM process via utilizing simulation models. The simulation model considered five main reactions and calculated the properties of the gas mixture considering temperatures and compositions. Using the simulation model, the distribution of gas mole fractions and temperatures were obtained. According to the results, the H2 yield and CO2 conversion rate increased with increasing operating temperature. The temperature of the catalyst bed decreased rapidly owing to the endothermicity of the reaction. Additionally, the CH4 conversion rate increased with increasing proportion of CO2, whereas the reaction converged to an equilibrium state and the temperature difference in the catalyst bed decreased with decreasing gas flow rate.

Dry reforming of methane for syngas production over noble metals modified M-Ni@S-1 catalysts (M = Pt, Pd, Ru, Au)

High tendency to sinter and carbon deposition becomes the choke point of Ni-based catalyst for its performance optimization in syngas generation via dry reforming of methane (DRM). Uniting the encapsulation of support with the construction of alloy interfaces, is a bright strategy to protect metallic Ni sites and synthesize highly efficient and stable Ni-based catalyst. Herein, M-Ni@S-1 catalysts (M = Pt, Pd, Ru, Au) with the same noble metal content (0.5 wt%) rather than moles were fabricated, and evaluated in DRM process. Results reveal that the type of noble metals influences the cooperating effect of the formed M − Ni alloy interface and support encapsulation degree, which achieves the best in Pt–Ni@S-1 catalyst. Therefore, Pt–Ni@S-1 catalyst exhibited outstanding sinter resistance and carbon tolerance as well as high catalytic stability, and obtained the highest methane conversion of approximately 80% at 700 °C and 60,000 mL·min−1·gcat−1 of GHSV. This can attribute to the small particle size of 3 nm, suitable metal-support interaction, abundant surface alkaline sites and stably existed Pt–Ni binary alloy interfaces.

Use of Pd-Ag Membrane Reactors for Low-Temperature Dry Reforming of Biogas-A Simulation Study.

Biogas is a valuable renewable energy source that can help mitigate greenhouse emissions. The dry reforming of methane (DRM) offers an alternative hydrogen production route with the advantage of using two main greenhouse gases, CO2 and CH4. However, its real application is limited mainly due to catalyst deactivation by coke formation and the reverse water gas shift (RWGS) reaction that can occur in parallel. Additionally, the typical dry reforming temperature range is 700-950 °C, often leading to catalyst sintering. A low-temperature DRM process could be in principle achieved using a membrane reactor (MR) to shift the dry reforming equilibrium forward and inhibit the RWGS reaction. In this work, biogas reforming was investigated through the simulation of MRs with thin (3.4 µm) and thick (50 µm) Pd-Ag membranes. The effects of the feed temperature (from 450 to 550 °C), pressure (in the range of 2-20 bar), and biogas composition (CH4/CO2 molar ratios from 1/1 to 7/3) were studied for the thin membrane through the calculation and comparison of several process indicators, namely CH4 and CO2 conversions, H2 yield, H2/CO ratio and H2 recovery. Estimation of the CO-inhibiting effect on the H2 molar flux through the membrane was assessed for a thick membrane. Simulations for a thin Pd-Ag MR show that (i) CO2 and CH4 conversions and H2 yield increase with the feed temperature; (ii) H2 yield and average rate of coke formation increase for higher pressures; and (iii) increasing CH4/CO2 feed molar ratio leads to higher H2/CO ratios, but lower H2 yields. Moreover, simulations for a thick Pd-Ag MR showed that the average H2 molar flux decreases due to the CO inhibiting effect (ca. 15%) in the temperature range considered. In conclusion, this work showed that for the considered simulation conditions, the use of an MR leads to the inhibition of the RWGS reaction and improves H2 yield, but coke formation and CO inhibition on H2 permeation may pose limitations on its practical feasibility, for which proper strategies must be explored.

Numerical Study of Dry Reforming of Methane in Packed and Fluidized Beds: Effects of Key Operating Parameters

Replacing the conventionally used steam reforming of methane (SRM) with a process that has a smaller carbon footprint, such as dry reforming of methane (DRM), has been found to greatly improve the industry’s utilization of greenhouse gases (GHGs). In this study, we numerically modeled a DRM process in lab-scale packed and fluidized beds using the Eulerian–Lagrangian approach. The simulation results agree well with the available experimental data. Based on these validated models, we investigated the effects of temperature, inlet composition, and contact spatial time on DRM in packed beds. The impacts of the side effects on the DRM process were also examined, particularly the role the methane decomposition reaction plays in coke formation at high temperatures. It was found that the coking amount reached thermodynamic equilibrium after 900 K. Additionally, the conversion rate in the fluidized bed was found to be slightly greater than that in the packed bed under the initial fluidization regime, and less coking was observed in the fluidized bed. The simulation results show that the adopted CFD approach was reliable for modeling complex flow and reaction phenomena at different scales and regimes.

Development of Photothermal Catalyst from Biomass Ash (Bagasse) for Hydrogen Production via Dry Reforming of Methane (DRM): An Experimental Study.

Conventional hydrogen production, as an alternative energy resource, has relied on fossil fuels to produce hydrogen, releasing CO2 into the atmosphere. Hydrogen production via the dry forming of methane (DRM) process is a lucrative solution to utilize greenhouse gases, such as carbon dioxide and methane, by using them as raw materials in the DRM process. However, there are a few DRM processing issues, with one being the need to operate at a high temperature to gain high conversion of hydrogen, which is energy intensive. In this study, bagasse ash, which contains a high percentage of silicon dioxide, was designed and modified for catalytic support. Modification of silicon dioxide from bagasse ash was utilized as a waste material, and the performance of bagasse ash-derived catalysts interacting with light irradiation and reducing the amount of energy used in the DRM process was explored. The results showed that the performance of 3%Ni/SiO2 bagasse ash WI was higher than that of 3%Ni/SiO2 commercial SiO2 in terms of the hydrogen product yield, with hydrogen generation initiated in the reaction at 300 °C. Using the same synthesis method, the current results suggested that bagasse ash-derived catalysts had better performance than commercial SiO2-derived catalysts when exposed to an Hg-Xe lamp. This indicated that silicon dioxide from bagasse ash as a catalyst support could help improve the hydrogen yield while lowering the temperature in the DRM reaction, resulting in less energy consumption in hydrogen production.

Strong metal-support interaction induced sintering-resistant Ni nanoparticles supported on highly CO2-activating vanadium hydroxyapatite for dry reforming of methane

Sintering of Ni-based catalysts and the following detrimental carbon depositions are still the major challenges to be overcame in the high-temperature dry reforming of methane (DRM) process. Herein, we for the first time induced classical strong metal-support interaction (SMSI) between Ni nanoparticles and vanadate substituted hydroxyapatite (VAP) under H2 atmosphere at as low as 300 ℃ (Ni/VAP-H300) to hinder the sintering of Ni nanoparticles during DRM process. TEM and element mapping analysis unambiguously exhibit the configuration of Ni nanoparticles encaged within the partially reduced VAP overlayer and subsequent linear-scan EDS investigations on the Ni/VAP-H300 at the reaction time of 25 h, 100 h and 260 h further elucidate the relatively intact VAP overlayer during the reaction, thus the CH4 conversion merely decreasing from 92 % to 79 % after stability test for 260 h. In contrast, Ni nanoparticles supported on conventional hydroxyapatite (Ni/HAP) give inferior stability, CH4 conversion drastically decreasing from 91 % to 42 % only after 25 h due to the absence of SMSI. Moreover, there also occurs electron-transfer between Ni nanoparticles and the adjacent VAP overlayer, thus showing higher CH4 decomposition activity compared with Ni/HAP. Combined with the excellent CO2-activating property of VAP support identified by CO2-TPD and gasification tests of the deposited carbon, the as-obtained Ni/VAP demonstrates outstanding initial activity and decent stability during DRM, which broadens the horizons of improving catalytic stability even under harsh reaction conditions by precisely exploiting the SMSI.

CO2 laser promoted oxygen vacancy-active oxygen cycle in DRM on Ni/CeO2

The global climate change has led to great interest in dry reforming of methane (DRM) to produce syngas from two greenhouse gases, CO2 and CH4. In order to investigate the reaction characteristics and mechanism under mid-infrared light irradiation, a 10.6 µm CO2 laser was introduced as an energy source to perform the complete DRM process on Ni/CeO2 at mild temperature. This scheme was compared with the traditional thermal mode under similar catalyst layer temperature. The laser-driven mode yielded significantly better performance around the DRM light-off temperature of the catalytic system, due to several-fold higher reactant conversion and product selectivity than in thermocatalytic mode. Based on a series of characterizations, the CO2 laser not only generated more than twice the number of oxygen vacancies than that in thermal mode at pre-reduction stage, but also enhanced the dissociative adsorption of CO2 and the circulation of oxygen vacancy-reactive oxygen at methane reforming stage. This study provides insight into the mechanism of CeO2 materials for DRM under mid-infrared illumination.

SiC-based structured catalysts for a high-efficiency electrified dry reforming of methane

The process of dry reforming of methane (DRM) can allow the conversion of methane and carbon dioxide, the two main greenhouse gases (GHG), into syngas which can be either used as feedstock for chemicals production or it can undergo through separation step for H2 recovery. However, the heat required for the reaction is obtained by combustion of fossil fuels, so CO2 footprint of the process is significant. Another problematic aspect of the process concerns the heat transfer to the catalytic volume: for allowing the catalytic bed to reach and maintain the reaction temperature, the heating medium outside the tubes containing the catalyst must have a temperature higher than 1000 °C. A process intensification could be performed by combining two innovative technologies: (i) the use of electrification for the energy supply (microwave heating and direct electrification) and (ii) the adoption of structured catalysts with high thermal conductivity.This work proposed the study of electrified DRM process using two Ni-based structured catalysts prepared starting by different carriers, a Silicon carbide (SiC) honeycomb monolith and a Si–SiC open-cell foam. The electrification of the DRM process has been realized by using either microwave heating or electrification through Joule (or ohmic) heating, and the experimental tests have been performed at different space velocity values. The configuration of the carriers has been carefully chosen in order to enhance the heat and mass transport phenomena, allowing to assure a flat temperature profile along the entire catalytic bed.The results have shown that the SiC monolith is more suitable than the Si–SiC foam for a microwave-assisted catalytic test. In fact, the higher fraction of void in the foam determines a lower heat absorption, and a consequently higher energy consumption (8.29 kWh/Nm3 H2 and 4.2 kWh/Nm3 H2, for the foam and the monolith respectively). Moreover, the monolith-based catalyst approached the thermodynamic equilibrium values in terms of CH4 conversion in all the investigated temperature range, while in the same tests the foam-based catalyst reached these values only at the higher temperatures. Conversely, the foam-based catalyst has shown the best performance in the electrification tests through Joule heating: the CH4 conversion approached the equilibrium values in the investigated temperature range and, more important, the energy consumption value was of 2.6 kWh/Nm3 H2, very close to the theoretical one (1.90 kWh/Nm3 H2) and equal to about ¼ of that obtained with microwaves.

Functionalization of inert silica to construct Si-O-Ni interfacial sites for stable dry reforming of methane

Silica (SiO2) has been widely used as inert support to better disperse and stabilize active metal nanoparticles. However, enhancing the interaction between the active metal and SiO2 could make inert silica to be active SiO2 with chemical functionalities that can be involved in the catalytic process. Here, a Ni doping-segregation SiO2 with post-annealing strategy was developed to achieve tunable Ni-SiO2 interaction with abundant interfacial Si-O-Ni sites. The synthesized NiSiOx catalysts with enhanced Ni-SiO2 interaction facilitate the formation of interfacial Si-O-Ni sites, which could inhibit the oxidation of Ni species and promote the removal of surface carbon species, leading to superior catalytic stability for dry reforming of methane (DRM). This work provides insights into the interfacial effect of SiO2-based catalysts, changing the traditional perception of inert SiO2 for the DRM process. The controlled metal-SiO2 interaction also allows SiO2 to be used to facilitate the catalytic process in various challenging reactions.

Promoted coke resistance of Ni by surface carbon for the dry reforming of methane.

Dry reforming of methane (DRM) is an efficient process to transform methane and carbon dioxide to syngas. Nickel could show good catalytic activity for DRM, whereas the deactivation of nickel surfaces by the formation of inert carbon structures is inevitable. In this study, we carry out a detailed investigation of the evolution and catalytic performance of the carbon-covered surface structure on Ni(100) with a combined density functional theory and microkinetic modeling approach. The results suggest that the pristine Ni(100) surface is prone to carbon deposition and accumulation under reaction conditions. Further studies show that over this carbon-covered reconstructed Ni(100) surface, a carbon-based Mars-van-Krevelen mechanism would be favored, and the activity and coke resistance is promoted. This surface state and reaction mechanism were rarely reported before and would provide more insights into the DRM process under real reaction conditions and would help design more stable Ni catalysts.

Constructing a stable 2D Ti3AlC2 MnAXm cocatalyst-modified gC3N4/CoAl-LDH/Ti3AlC2 heterojunction for efficient dry and bireforming of methane for photocatalytic syngas production

2D titanium aluminium carbide (Ti3AlC2) dispersed with cobalt aluminium layered double hydroxide (CoAl-LDH) and graphitic carbon nitride (g-C3N4) was designed to construct heterojunction with promising charge separation. The performance of the nanotextures was tested for gas flaring (CH4) reduction through photocatalytic dry reforming of methane (DRM) and bireforming of methane (BRM) under visible light irradiation. Coupling Ti3AlC2 with CoAl-LDH/g-C3N4 was found promising to enhance visible light absorption and charge carrier separation. Using ternary CoAl-LDH/g-C3N4/Ti3AlC2 composite and the DRM process, the highest yield rate for CO and H2 of 30.29 and 4.74 µmole g-1 h-1 at selectivity 86.46% and 13.53%, respectively were obtained. This photocatalytic efficiency was 8 and 5-fold higher than pure CoAl-LDH. This improved photocatalytic activity can be attributed to interfacial contact with Z-scheme heterojunction integrated with an exfoliated MAX structure for efficient electron conductivity. The effect of the feed ratio was further investigated, which revealed a direct impact on syngas production due to reactant adsorption competition over the catalyst surface. The higher yield rate of CO and H2 were obtained at a CO2/CH4 feed ratio of 1.0 due to equal opportunity to attach both the molecules to maximize the oxidation and reduction reactions. Likewise, stability analysis revealed excellent composite recyclability with continuous syngas production. Performance comparison with the bireforming process (BRM) revealed that adding H2O to the feed mixture generated more protons, activating the reversed water gas shift reaction (RWGSR), thus reducing the productivity of syngas. This study would provide a green and effective strategy towards gas flaring reduction by utilizing CH4 and CO2 simultaneously and reforming them into energy-efficient renewable fuels, which serves the dual purposes of flaring reduction and utilization.

Hierarchical core–shell Ni@C-NCNTs nanocomposites tailored for microwave-induced dry reforming of methane process

Hierarchical core–shell Ni@C-NCNTs nanomaterials and N-doped defects for microwave-induced CH4 dry reforming with excellent catalytic activity and energy efficiency.