Activity In Dry Reforming Of Methane Research Articles

Dry Reforming of Methane over Pyrochlore-Type La2Ce2O7-Supported Ni Catalyst: Effect of Particle Size of Support.

The properties of supports (such as oxygen vacancies, oxygen species properties, etc.) significantly impact the anti-carbon ability due to their promotional effect on the activation of CO2 in dry reforming of methane (DRM). Herein, pyrochlore-type La2Ce2O7 compounds prepared using co-precipitation (CP), glycine nitrate combustion (GNC) and sol-gel (S-G) methods, which have highly thermal stability and unique oxygen mobility, are applied as supports to prepare Ni-based catalysts for DRM. The effect of the calcining temperature (500, 600 and 700 °C) on La2Ce2O7(CP) has also been investigated. Based on multi-technique characterizations, it is found that the synthesis method and calcination temperature can influence the particle size of the La2Ce2O7 support. Changes in particle size strongly modulate the pore volume, specific surface area and numbers of surface oxygen vacancies of the La2Ce2O7 support. As a result, the distribution of supported Ni components is affected due to the different metal-support interaction, thereby altering the activity of the catalysts for cracking CH4. Moreover, the supports' abilities to adsorb and activate CO2 are also adjusted accordingly, accelerating the removal of the carbon deposited on the catalysts. Finally, La2Ce2O7(CP 600) with an appropriate particle size exhibits the best catalytic activity and stability in DRM.

Local coordination environment triggers key Ni-O-Si copolymerization on silicalite-2 for dry reforming of methane

The development of dry reforming of methane (DRM) catalysts with good Ni loading, while retaining high metal dispersion is a critical issue, given the harsh industrial-relevant conditions. Here, we demonstrate the impact of the local coordination environment on the DRM activity of Ni-silicalite-2 (Ni-S2) catalysts. The grafted Ni(II) intermediates with high Ni-O-Si copolymerization (coordination number ratio Si: Ni=2.28) are discovered to redisperse Ni sites, even at 10 wt% Ni loading. Then, the partial S2 recrystallizes into new SiO2-nanowires to anchor Ni nanoparticles, via an ethylenediamine-assisted dissolution-recrystallization (enDR). Compared to the typical Ni-S2 catalyst with Ni phyllosilicate (CN ratio Si: Ni＜1), the Ni-S2-enDR shows high dispersion and stability at 800 °C and 450 L gcat−1 h−1, exhibiting negligible coke deposition and no growth of 4.25 nm Ni nanoparticles. The atomic level insights in nickel and silicon coordination reported in this work provide an instructive way of designing stable DRM catalysts.

Deciphering the role of nano-CeO2 morphology on the dry reforming of methane over Ni/CeO2 using transient and isotopic techniques

The effect of ceria morphology, nanorods-NR and nanopolyhedra-NP on important kinetic parameters of the dry reforming of methane (DRM) over Ni/nano-ceria (dNi ∼20 nm) was investigated by transient and isotopic experiments. Transient isothermal reduction by hydrogen evidenced lower activation energy and higher reduction rates of lattice oxygen in the case of CeO2-NR compared to those of CeO2-NP. Transient 16O/18O isotopic exchange provided a lower Eapp of bulk oxygen diffusion (by ∼90 kJ mol−1) for CeO2-NR compared to CeO2-NP. 18O/16O isotopic exchange followed by DRM revealed higher carbon oxidation rates by lattice oxygen to C18O(g) in the case of CeO2-NR compared to those of CeO2-NP, in harmony with the lower amount of carbon accumulated in the former catalyst. The lower Eapp of DRM and carbon oxidation by lattice oxygen confirm the higher DRM activity on Ni/CeO2-NR compared to Ni/CeO2-NP. HAADF-STEM and Raman studies were linked to the observed transient kinetic results.

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.

High activity in the dry reforming of methane using a thermally switchable double perovskite and in situ generated molecular level nanocomposite.

This work emphasizes the dry reforming of methane (DRM) reaction on citrate sol-gel-synthesized double perovskite oxides. Phase pure La2NiMnO6 shows very impressive DRM activity with H2/CO = 0.9, hence revealing a high prospect of next-generation catalysts. Although the starting double perovskite phase gets degraded into mostly binary oxide phases after a few hours of DRM activity, the activity continues up to 100 h. The regeneration of the original double perovskite out of decomposed phases by annealing at near synthesis temperature, followed by the spectacular retention of activity, is rather interesting and hitherto unreported. This result unravels unique reversible thermal switching between the original double perovskite phase and decomposed phases during DRM without compromising the activity and raises challenge to understand the role of decomposed phases evolved during DRM. We have addressed this unique feature of the catalyst via structure-property relationship using the in situ generated molecular level nanocomposite.

Coating Effects of Sm0.2Ce0.78M0.02O2- δ (M=Ni, Co, Pd, NiCo) Layer on Ni/YSZ Anode for Internal Dry Reforming in Solid Oxide Fuel Cells

Internal dry reforming of methane (DRM) in solid oxide fuel cells (SOFCs) has environmental advantages because CH4 and CO2 are considered as two major greenhouse gases causing global warming. Carbon coking, however, can be major drawback in the DRM via pyrolysis of methane and Boudouard reaction. In this study, Sm0.2Ce0.78M0.02O3- δ (SCM, M=Ni, Co, Pd, NiCo) was investigated to minimize carbon coking and to improve the catalytic activity for internal DRM in SOFCs. Samarium doped ceria (Ce0.8Sm0.2O2- δ) has been widely used in SOFCs due to the excellent ionic conductivity and the mixed ionic and electronic conductivity (MIEC). To improve the catalytic activity of Ce0.8Sm0.2O2- δ, Ni, Co, Pd, and NiCo alloy were substituted into the Ce. The SCM phase was stable in internal DRM condition. The morphology and compositions are analyzed with XRD, SEM, TEM, XPS, etc. Sm0.2Ce0.78Ni0.01Co0.01O2- δ(SCNC) showed excellent DRM results with over 90% in CH4 and CO2 conversion and close to 1 in H2/CO selectivity at 800oC. The carbon deposition of SCNC catalysts was minimized. In addition, power density of SCNC-coated Ni/YSZ anode was improved with 2.3 times higher in CH4/CO2 fuel conditions comparing to that of Ni/YSZ anode.

La2O3-CeO2-Supported Bimetallic Cu-Ni DRM Catalysts.

The present work is focused on nickel catalysts supported on La2O3-CeO2 binary oxides without and with the addition of Cu to the active component for the dry reforming of methane (DRM). The catalysts are characterized using XRD, XRF, TPD-CO2, TPR-H2, and low-temperature N2 adsorption-desorption methods. This work shows the effect of different La:Ce ratios (1:1 and 9:1) and the Cu addition on the structural, acid base, and catalytic properties of Ni-containing systems. The binary LaCeOx oxide at a ratio of La:Ce = 1:1 is characterized by the formation of a solid solution with a fluorite structure, which is preserved upon the introduction of mono- or bimetallic particles. At La:Ce = 9:1, La2O3 segregation from the solid solution structure is observed, and the La excess determines the nature of the precursor of the active component, i.e., lanthanum nickelate. The catalysts based on LaCeOx (1:1) are prone to carbonization during 6 h spent on-stream with the formation of carbon nanotubes. The Cu addition facilitates the reduction of the Cu-Ni catalyst carbonization and increases the number of structural defects in the carbon deposition products. The lanthanum-enriched LaCeOx (9:1) support prevents the accumulation of carbon deposition products on the surface of CuNi/La2O3-CeO2 9:1, providing high DRM activity and an H2/CO ratio of 0.9.

Understanding Coke Deposition Vis-à-Vis DRM Activity over Magnesia-Alumina Supported Ni-Fe, Ni-Co, Ni-Ce, and Ni-Sr Catalysts.

The catalytic conversion of CH4 and CO2 into H2-rich syngas is known as the dry reforming of methane (DRM). The dissociation of CH4 over active sites, coupled with the oxidation or polymerization of CH4-x (x = 1-4), plays a crucial role in determining in determining the DRM product yield and coke deposition. Herein, a series of bimetallic-supported catalysts are prepared by the dispersion of Ni-M (M = Ce, Co, Fe, and Sr) over 60 wt% MgO-40 wt% Al2O3 (60Mg40Al) support. Catalysts are tested for DRM and characterized with XRD, surface area and porosity, temperature-programmed reduction/desorption, UV-VIS-Raman spectroscopy, and thermogravimetry. 2.5Ni2.5Sr/60Mg40Al and 2.5Ni2.5Fe/60Mg40Al, and 2.5Ni2.5Ce/60Mg40Al and 2.5Ni2.5Co/60Mg40Al have similar CO2 interaction profiles. The 2.5Ni2.5Sr/60Mg40Al catalyst nurtures inert-type coke, whereas 2.5Ni2.5Fe/60Mg40Al accelerates the deposition of huge coke, which results in catalytic inferiority. The higher activity over 2.5Ni2.5Ce/60Mg40Al is due to the instant lattice oxygen-endowing capacity for oxidizing coke. Retaining a high DRM activity (54% H2-yield) up to 24 h even against a huge coke deposition (weight loss 46%) over 2.5Ni2.5Co/60Mg40Al is due to the timely diffusion of coke far from the active sites or the mounting of active sites over the carbon nanotube.

Synergistic effect of macroporosity and crystallinity on catalyst deactivation behavior over macroporous Ni/CexZr1-xO2–Al2O3 for dry reforming of methane

Dry reforming of methane (DRM) is an outstanding process for transforming methane and carbon dioxide into synthesis gases (H2 and CO). In this study, a special geometrical modification on Ni/CexZr1-xO2–Al2O3 catalyst was applied by introducing a macroporous structure into the support to accelerate the metal support interaction that optimized the distribution of the active sites over the catalyst. Furthermore, we investigated a synergistic effect of the macroporosity and CexZr1-xO2 (CZ) crystallinity over the Ni/CexZr1-xO2–Al2O3 catalyst on its catalytic performance in DRM. Macroporous Ni/CexZr1-xO2–Al2O3 catalysts were prepared via washing (Ni-MaCZA-W) and hydrothermal (Ni-MaCZA-H) methods. Non-macroporous Ni-CZA-H with crystalline CZ was prepared for comparison. The crystalline CZ over macroporous Ni-MaCZA-H had a strong interaction with Ni due to easy accessibility of Ni species to CZ in the macroporous support, resulting in highly dispersed Ni nanoparticles and abundant oxygen vacancies. The unique properties of Ni-MaCZA-H increased catalytic activity and stability in DRM, suppressing coke formation via efficient coke gasification. The Ni species and amorphous CZ over Ni-MaCZA-W resulted in a bimodal Ni size distribution and fast catalyst deactivation. However, even though the crystalline CZ over Ni-CZA-H generated a unimodal distribution of Ni nanoparticles, the non-macroporous Ni-CZA-H resulted in gradual deactivation in the catalytic activity and the production of a different type of coke.

A novel strategy for the fabrication of highly active and stable hydrochar-based catalysts for efficient dry reforming of methane

Strong metal-support interaction (SMSI) has pivotal importance for stabilizing metal sites and tuning catalytic performance in high-temperature gas phase chemistry. Conventional SMSI construction strategy, however, suffers from limited exposure of active sites caused by gas or thermally-induced metal redistribution and heavily deteriorates the catalytic performance. Herein we showed that the rationally constructed metal–carbon interface by pressure-induced SMSI greatly impacted the activity of core–shell nickel nanoparticles supported on hydrochar (Ni/NiO/HC) in dry reforming of methane (DRM). The electronic and geometric structures of Ni/NiO/HC were effectively tailored by simply adjusting the compression pressure. In particular, the NiO shell thickness was highly sensitive to compression pressure, which could be precisely manipulated from 2 to 5 atomic layers by imposing the pressures from ambient to 3.6 Gpa. With the optimized thickness of NiO shell of 3–5 atomic layers, the highest activity of Ni/NiO/HC catalysts were up to 57.2 times than their uncompressed analogues in DRM, and far outperformed benchmarks in the literature, especially at low reforming temperatures (500–600 °C). The active sites responsible for this promising performance were associated with the fraction of low-coordinated corner and perimeter Ni atoms from 20.1 to 61.6%, which dramatically enhanced the DRM activity of Ni/NiO/HC catalysts over 2 orders of magnitude. This study introduced a new paradigm for SMSI construction via a pressure-induced construction strategy and highlighted the importance of a rationally designed core–shell metal particles/hydrochar interface.

Coke resistant NiCo/CeO2 catalysts for dry reforming of methane derived from core@shell Ni@Co nanoparticles

Core@shell Ni@Co and bimetallic alloyed Ni–Co nanoparticles with controlled Co/Ni compositions were prepared and supported on CeO2 to investigate their performance in catalytic dry reforming of methane (DRM) and occurrence of sintering and coking. Increasing the Co/Ni ratio significantly reduced coke deposition while maintaining catalytic activity for DRM. However, a Co/Ni ratio > 1 caused a rapid decrease in activity. The Ni@Co1/CeO2 catalyst exhibited the highest CH4 and CO2 conversions, with long-term stability during DRM at 800 °C for 100 h. The initial core@shell structure of the Ni@Co1/CeO2 catalyst transformed to a homogeneous alloy after DRM at 800 °C for 10 h, losing its Co shell. However, the bimetallic alloyed Ni–Co1/CeO2 catalyst transformed into a non-uniform alloy rich in Co on the surface after DRM for 10 h. As the elemental distribution of the NPs becomes more homogeneous, Ni–Co1/CeO2 exhibit similar catalytic activity to Ni@Co1/CeO2 after 50 h. The oxygen vacancies on the CeO2 surface provided oxygen atoms to the Ni surface, removing carbon species deposited and releasing CO. Therefore, Ni@Co1/CeO2 catalyst provides excellent catalytic activity and stability due to the rapid formation of a homogenous alloy and the synergistic effect of Co and CeO2.

Engineering the Interface and Interaction Structure on Highly Coke-Resistant Ni/CeO2-Al2O3 Catalyst for Dry Reforming of Methane

Designing and tailoring metal-support interaction in Ni-based catalysts with plentiful interfacial sites is of significant interest for achieving a targeted catalytic performance in dry reforming of methane (DRM), but remains as a challenging task. In this work, Ni/Al2O3 and Ni/CeO2-Al2O3 catalysts with the same strong metal-support interaction (SMSI) but distinct interface structure are developed by an improved evaporation-induced self-assembly method using pseudobohemite gel as aluminum source. Ni/CeO2-Al2O3 exhibits superior catalytic activity and stability in DRM in comparison with Ni/Al2O3. The highest CH4 and CO2 conversion reaches at 71.4% and 82.1% for Ni/CeO2-Al2O3, which are higher than that of 64.3% and 75.6% for Ni/Al2O3 at 700 °C. The SMSI effect in Ni/CeO2-Al2O3 provides more active interfacial sites with less coke deposition, and promotes the generation of active formate species which are the key intermediates for DRM. The findings of the present work could possibly pave the way for fabricating catalysts with SMSI strategy for efficient heterogeneous catalysis.

Process-intensified protonic ceramic fuel cells for power generation, chemical production, and greenhouse gas mitigation

•Simultaneous power generation, chemical production, and greenhouse gas mitigation •Sm0.2Ce0.7Ni0.1Ru0.05O2-δ catalyst was designed for dry reforming of methane •Extensive studies were performed to probe the synergistic impacts of Ni and Ru •At 650°C, the DRM-PCFC attained a peak power density of 0.94 W cm−2 Here, we present protonic ceramic fuel cells (PCFCs) that achieve the internal dry reforming of methane (DRM) at 550°C–650°C to simultaneously generate power, produce syngas or hydrogen as chemical building blocks, and to mitigate two harmful greenhouse gases. We developed an oxide-supported in situ exsolved Ni-Ru catalyst (Sm0.2Ce0.7Ni0.1Ru0.05O2-δ, i.e., SDC-Ni-Ru). The in situ exsolved Ru clusters favor the CO2 activation step, while the Ni clusters promote the CH4 activation. The synergy between Ni and Ru clusters simultaneously improves the CH4 and CO2 activation, enhancing the DRM activity. Additionally, we discovered that the Ru clusters alter the DRM pathway, favoring the formation of monodentate carbonate species, which subsequently accelerates the oxidization of −CH∗ species on Ni clusters and improves the coking tolerance. The PCFCs equipped with this SDC-Ni-Ru internal DRM catalyst attain exceptional and durable power densities using a mixture of CH4 and CO2 as the fuel, setting a record for DRM-PCFCs. Here, we present protonic ceramic fuel cells (PCFCs) that achieve the internal dry reforming of methane (DRM) at 550°C–650°C to simultaneously generate power, produce syngas or hydrogen as chemical building blocks, and to mitigate two harmful greenhouse gases. We developed an oxide-supported in situ exsolved Ni-Ru catalyst (Sm0.2Ce0.7Ni0.1Ru0.05O2-δ, i.e., SDC-Ni-Ru). The in situ exsolved Ru clusters favor the CO2 activation step, while the Ni clusters promote the CH4 activation. The synergy between Ni and Ru clusters simultaneously improves the CH4 and CO2 activation, enhancing the DRM activity. Additionally, we discovered that the Ru clusters alter the DRM pathway, favoring the formation of monodentate carbonate species, which subsequently accelerates the oxidization of −CH∗ species on Ni clusters and improves the coking tolerance. The PCFCs equipped with this SDC-Ni-Ru internal DRM catalyst attain exceptional and durable power densities using a mixture of CH4 and CO2 as the fuel, setting a record for DRM-PCFCs.

Preparing a Zr-Doped CeO2 Nanorod to Improve the Catalytic Performance of the Ni-Based Catalyst for Dry Reforming of Methane by Enhancing Oxygen Supply

Dry reforming of methane (DRM) is a feasible route to realize the resource utilization of greenhouse gases CO2 and CH4. The Ni-based catalyst is recognized as a potential catalyst for the industrialization of DRM. However, catalyst deactivation caused by carbon deposition is a challenge. Providing enough active oxygen species to accelerate the reaction between CHx (x = 0–3) and oxygen species is the key to inhibit coking. Ni-based catalysts loaded on a Zr-doped Ce1–xZrxO2 nanorod were prepared by a one-step hydrothermal method. Benefiting from lattice distortion caused by Zr doping, the Ni/Ce0.95Zr0.05O2 catalyst showed the best catalytic activity and stability. Compared with the Ni/CeO2 catalyst, the activation energy of CH4 and CO2 decreased by 20 and 22%, respectively. The 100 h stability test showed that the Ni/CeO2 catalyst was 10% deactivated, and the carbon deposition rate was 0.82 mgc·gcat·–1·h–1, while the Ni/Ce0.95Zr0.05O2 catalyst showed excellent stability. The extensive characterization of the catalysts indicated that the enhancement in DRM activity upon Zr doping could be attributed to the increase of oxygen vacancies and the improvement in lattice oxygen mobility. However, excessive Zr doping formed ZrO2 covering oxygen vacancies, resulting in decreased catalytic activity and stability. The results showed that lattice oxygen over the Ni/Ce0.95Zr0.05O2 catalyst not only participated in the oxidation of carbon intermediates but also contributed to the deep dissociation of CH4 over Ni through an oxygen-mediated dissociation pathway. Similarly, the redox cycle on the oxygen vacancies was also important for enhancing the CO2 adsorption activation to relieve the coking of the catalyst.

Temperature hysteresis in dry reforming of methane on Ni/SBA-15 catalyst: Low temperature activity originated from the synergy of Ni0 and carbon nanotubes

The origins of temperature hysteresis and low temperature activity on Ni/SBA-15 for dry reforming of methane (DRM) were studied. The catalyst structural evolution under different conditions was characterized by Quasi-in-situ XPS, XRD, TG-MS, TEM, and DRM activity test. When heating up in DRM atmosphere, only at 425 °C (ignition temperature, Tign), H2 and CO were observed, whereas in cooling, the activity dropped to 0% at 295 °C (extinguishing temperature, Text), forming temperature hysteresis. Below Tign, surface Ni0 was oxidized to NiO by CO2 in feed or support oxygen, whereas at Tign, NiO reduction and methane decomposition occurred, generating carbon nanotubes, which improved the oxidation resistance of Ni0, and the synergetic effect of Ni0 and carbon nanotubes led to stable activity at about 300 °C. The insight provides basic information for new catalyst design for low temperature activation of both CH4 and CO2, and understanding of related phenomena.

Genesis of Active Pt/CeO2 Catalyst for Dry Reforming of Methane by Reduction and Aggregation of Isolated Platinum Atoms into Clusters.

Atomically dispersed metal catalysts offer the advantages of efficient metal utilization and high selectivities for reactions of technological importance. Such catalysts have been suggested to be strong candidates for dry reforming of methane (DRM), offering prospects of high selectivity for synthesis gas without coke formation, which requires ensembles of metal sites and is a challenge to overcome in DRM catalysis. However, investigations of the structures of isolated metal sites on metal oxide supports under DRM conditions are lacking, and the catalytically active sites remain undetermined. Data characterizing the DRM reaction-driven structural evolution of a cerium oxide-supported catalyst, initially incorporating atomically dispersed platinum, and the corresponding changes in catalyst performance are reported. X-ray absorption and infrared spectra show that the reduction and agglomeration of isolated cationic platinum atoms to form small platinum clusters/nanoparticles are necessary for DRM activity. Density functional theory calculations of the energy barriers for methane dissociation on atomically dispersed platinum and on platinum clusters support these observations. The results emphasize the need for in-operando experiments to assess the active sites in such catalysts. The inferences about the catalytically active species are suggested to pertain to a broad class of catalytic conversions involving the rate-limiting dissociation of light alkanes.

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.

Ni, Co and Ni-Co-Modified Tungsten Carbides Obtained by an Electric Arc Method as Dry Reforming Catalysts

Dry reforming of methane (DRM), to produce synthesis gas, is one of the most important chemical reactions used for the industrial production of hydrogen and leads to the synthesis of hydrocarbons (liquid fuels) and other valuable products. A cost-effective alternative to active and stable noble metal DRM catalysts, with comparable catalytic performance, can be composite materials based on nickel, cobalt and transition metal carbides. In this line, the present work proposes a non-standard way to obtain dry reforming catalysts of Ni, Co and Ni-Co-modified tungsten carbide (WC) produced by an electric arc method. Different amounts of nickel, cobalt and their mixtures were deposited on tungsten carbide by deposition-precipitation with NaOH (DP) and incipient wetness impregnation (IWI) methods. The resulting materials were characterized by N2 adsorption-desorption, transmission electron microscopy, energy dispersive spectroscopy, X-ray diffraction and X-ray photoelectron spectroscopy, and their performance was evaluated in DRM. The composition and preparation method of catalysts predetermined their structural, textural and electronic properties, playing a decisive role in their activity for DRM. DP-prepared 20%Ni/WC material remained resistant to oxidation, both that of the active metal (nickel) and of the tungsten carbide, as well as to coking during DRM. This sample proved to be the most active and stable among all studied materials. Possibly, the resistance to oxidation and coking was due to a more efficient implementation of the oxidation/(re)carbonization cycle on the surface of this catalyst.

An in situ defect engineering approach for light-driven methane dry reforming over atomically distributed nickel

Dry reforming of methane economically converts methane and carbon dioxide into syngas (hydrogen and carbon monoxide) but requires high energy and often suffers from catalyst instability. Here, a surface-modulation strategy is demonstrated via decorating in situ defects on isolated nickel (Ni) atoms over La2O3 for boosting light-driven dry reforming of methane activity. Atomically dispersed 0.5Ni/La2O3 achieves a hydrogen evolution rate of 170.9 mol gNi−1 h−1. The reactivity is mainly attributed to photogenerated electrons, which overcome the limitations of a purely thermal system. The in situ generation of oxygen vacancies increases the initial-stage reactivity, where oxygen vacancies act as electron traps to accelerate charge separation and promote the adsorption/activation of reactants. The 0.5Ni/La2O3 catalyst exhibits strong inhibition of carbon coking and is sintering resistant, benefiting from the synergy between in situ oxygen vacancies and isolated nickel atoms.

Dry reforming of methane for syngas production over attapulgite-derived MFI zeolite encapsulated bimetallic Ni-Co catalysts

Dry reforming of methane (DRM) shows bright prospects for the treatment and value-added utilization of greenhouse gas, and catalyst inactivation has been a long-standing grand challenge for this process. Here, a catalyst of attapulgite-derived MFI (ADM) zeolite encapsulated Ni-Co alloys was synthesized using a one-pot method. Characterization results demonstrated that the Ni-Co alloys, which could be stably presentduring DRM process, favored the formation of electron-rich Ni metal sites and thus significantly enhanced C-H bond breaking ability. Meanwhile, the ADM zeolite not only firmly anchored metallic sites by pore or layer confinement, but also provided abundant CO2 adsorption/activation centers. These contributed to the improved anti-sinter and anti-coke ability as well as superior DRM activity of 10Ni1Co@ADM-0.1 catalyst. This work is expected to supply guidance for the development of clay-based metallic Ni catalysts and its application in DRM for syngas production.