Ni-based Catalysts Research Articles

Unlocking naphtha from polyolefins using Ni-based hydrocracking catalysts

Naphtha (C5-C12 alkanes) is a platform feedstock in the petroleum industry and an ideal target for reutilizing plastic waste at scale. Hydrocracking has emerged as a promising technology for deconstructing polyolefins to naphtha. However, contemporary catalysts rely on Pt to achieve high rates, while earth-abundant metals (EAM) perform poorly. Herein, we develop high-performance Ni/BEA catalysts for polyolefin hydrocracking, achieving complete low-density polyethylene (LDPE) deconstruction with 80 % maximum naphtha yield within 12 h at 250 °C, 60 bar H2, and a catalyst-to-polymer ratio of 1:100. These catalysts are versatile, accommodating virgin resins and commercial polymer products, and are directly reusable and regenerable. Comparative analysis highlights that 5Ni/BEA(25) exhibits the highest naphtha productivity of 11.4 gNaphthagcat∙h, surpassing previously reported Pt- and EAM-based catalysts by 2.5–6.2x. Technoeconomic and life-cycle analyses reveal naphtha from LDPE hydrocracking is economically and environmentally competitive to fossil-fuel-derived naphtha. These advancements pave the way for the industrial implementation of earth-abundant Ni-based catalysts in polyolefin hydrocracking, followed by retrofitting steam crackers to address plastics waste at scale.

Ce enhanced RuNi alloy multi-metal synergic hydrotalcite oxide derived catalyst for high performance CO2 methanation

Ni-based methanation catalysts have problems such as low temperature activity and easy sintering. The high cost of supported Ru-based methanation catalysts limits their application in industrialization. In this work, a hydrotalcite precursor Ru-Ni-Ce-Y catalyst was prepared by co-precipitation method, and the hydrotalcite oxide catalyst was prepared by high temperature calcination. The hydrotalcite oxide catalyst was prepared by optimizing the ratio of Ni element and the amount of precious metal and rare earth metal. Compared with the traditional supported catalyst, the activity of Ru1Ni80Ce4Y20 was significantly improved. It is confirmed from the experimental results that the medium basic sites, oxygen vacancies and the synergistic effect between RuNi alloy and Ce are the reasons for the high performance of Ru1Ni80Ce4Y20. It provides a thought for the design of highly active, stable and low cost methanation catalysts in industrial methanation production.

Nickel nanoparticles supported on doped graphene-based materials for the ORR and HER in alkaline medium

In this work, Ni nanoparticles (NPs), with nominal metallic loading of 20 wt%, were deposited on graphene-based materials (GMs) doped with nitrogen and sulphur, in order to study their electrocatalytic activity towards the oxygen reduction reaction (ORR) and hydrogen evolution reaction (HER) in alkaline medium. Different chemical reducing agents were employed to synthesize the catalysts. Results indicate that the presence of heteroatoms in the GMs influences the activity of both the GMs and the Ni-based catalysts. Thus, best results were obtained for catalyst containing nitrogen and sulphur for the ORR which favours the direct four-electron pathway, whereas for the HER, the highest performance was observed for N-doped materials.

An efficient and stable LDH-derived Ni catalyst for highly selective hydrogenation of nitriles to primary amines

Transformation of nitriles into amines is highly desired, yet stable non-noble metal heterogeneous catalysts for efficiently selective production of primary amine are still lacking.Herein, for the first time we reported a Zr-doped yolk-shell structured Ni-based catalyst derived from layered double hydroxides (LDH) in the selective hydrogenation of nitriles to primary amines. The prepared catalyst exhibited higher primary amine yield (benzylamine yield >99.9 %) and significantly higher stability (>200 h) than highly efficient Ni catalysts that are reported previously in the selective hydrogenation of benzonitrile. Other nitriles are transformed into primary amines with good yields (90–100 %). The strong interaction between Ni0yolk and shell investsNiAl catalysts with robust stability. Importantly, Zr promotes the migration of Ni2+in the shell, resulting in appropriate acidity and better hydrogen activation capability, which drives the reaction aggressively to the BA formation pathway, and thussuccessfully enhances the yield of primary amine above 99.9 %.

Perovskite-Derivative Ni-Based Catalysts for Hydrogen Production via Steam Reforming of Long-Chain Hydrocarbon Fuel

Large-scale hydrogen production by the steam reforming of long-chain hydrocarbon fuel is highly desirable for fuel-cell application. In this work, LaNiO3 perovskite materials doped with different rare earth elements (Ce, Pr, Tb and Sm) were prepared by a sol-gel method, and the derivatives supported Ni-based catalysts which were successfully synthesized by hydrogen reduction. The physicochemical properties of the as-prepared catalysts were characterized by powder X-ray diffraction, high-resolution transmission electron microscopy, N2 adsorption–desorption isotherms, H2 temperature-programmed reduction, and X-ray photoelectron spectroscopy. The catalytic performance of the as-prepared catalysts for hydrogen production was investigated via the steam reforming of n-dodecane. The results showed that the catalyst forms perovskite oxides after calcination with abundant mesopores and macropores. After reduction, Ni particles were uniformly distributed on perovskite derivatives, and can effectively reduce the particles’ sizes by doping with rare earth elements (Ce, Pr, Tb and Sm). Compared with the un-doped catalyst, the activity and hydrogen-production rate of the catalysts are greatly improved with rare earth element (Ce, Pr, Tb and Sm)-doped catalysts, as well as the anti-carbon deposition performance. This is due to the strong interaction between the uniformly distributed Ni particles and the support, as well as the abundant oxygen defects on the catalyst surface.

Ni-based bimetallic catalysts for hydrogen production via (sorption-enhanced) steam methane reforming

The catalytic performance of a monometallic Ni/Al2O3 and three bimetallic catalysts (Ni3M1/Al2O3, with M = Cu, Fe, and Ge) for the (sorption-enhanced) steam methane reforming reaction was evaluated. Ni3Cu1/Al2O3 was found to be the optimal catalyst in terms of methane conversion, hydrogen yield, and purity. Ge also has a promoting effect on the monometallic Ni catalyst, whereas the addition of Fe negatively influenced its performance. Physico-chemical characterization of the materials indicated the formation of alloys upon activation of the materials with hydrogen. The addition of Cu increased the surface area and metal dispersion, and improved the overall morphology of the catalyst. The experimental observations were also supported by a numerical study combining Density Functional Theory-based calculations and Microkinetic modelling of the SMR process. Ni3Cu1 and Ni3Ge1 were calculated to have a similar level of catalytic activity as Ni, whereas Ni3Fe1 was unsuitable for the reaction. The SMR reaction was further improved by adding calcium oxide as the CO2 sorbent, which increased methane conversion, CO selectivity, hydrogen yield, and hydrogen purity. The highest methane conversion of 97 % was achieved by Ni/Al2O3 and Ni3Cu1/Al2O3 at 700 °C.

Resolving the Active Role of Isolated Transition Metal Species in Ni-Based Catalysts for Dry Reforming of Methane

Resolving the Active Role of Isolated Transition Metal Species in Ni-Based Catalysts for Dry Reforming of Methane

Enhanced low-temperature CO2 methanation over La-promoted NiMgAl LDH derived catalyst: Fine-tuning La loading for an optimal performance

LDH-derived Ni-based catalysts are gathering momentum due to their excellent thermal stability but their low-temperature CO2 methanation is limited. In this study, various concentrations of La were introduced into the LDH-derived Ni-based catalysts for CO2 methanation, and the underlying mechanisms were investigated. The optimal Ni/La0.2-MgAlOx catalyst presented a CO2 conversion level of 69.0 % at 225 °C, which is over 7 times higher than that of conventional Ni/MgAlOx. The addition of small amounts of La could significantly enhance H spillover to promote the reduction of Ni species, but the oxygen vacancy concentration became the dominant factor causing changes in low-temperature activity as the La contents continue to increase. CO2 was found to be adsorbed at the oxygen vacancies in the form of bidentate carbonates, which are more reactive under an enhanced electron-rich environment. The research offers guidance to design effective and sustainable catalysts for low-temperature CO2 methanation.

Primary alcohols as killers of Ni-based catalysts in transfer hydrogenation

The effect of different types of alcohols used as hydrogen donors on the activity of a metal Ni-based catalyst in the hydrogenation of benzofuran as a model substrate under transfer hydrogenation conditions has been studied. The hydrogenation process of benzofuran using 2-PrOH as a hydrogen donor leads sequentially to dearomatization and then to deoxygenation of the substrates. At the same time, the use of primary alcohols such as MeOH, EtOH and 1-PrOH as hydrogen donors leads to irreversible deactivation of the Ni-containing catalyst. A clear mechanism of deactivation of Ni-based metal catalysts by primary alcohols has been established. The interaction of the catalyst with primary alcohols at a temperature of 250 °C leads to the formation of an inactive Ni3C carbide phase, as well as sintering and segregation of metal particles on the surface of the alumina support.

Recent Advances in Coke Management for Dry Reforming of Methane over Ni-Based Catalysts

The dry reforming of methane (DRM) is a promising method for controlling greenhouse gas emissions by converting CO2 and CH4 into syngas, a mixture of CO and H2. Ni-based catalysts have been intensively investigated for their use in the DRM. However, they are limited by the formation of carbonaceous materials on their surfaces. In this review, we explore carbon-induced catalyst deactivation mechanisms and summarize the recent research progress in controlling and mitigating carbon deposition by developing coke-resistant Ni-based catalysts. This review emphasizes the significance of support, alloy, and catalyst structural strategies, and the importance of comprehending the interactions between catalyst components to achieve improved catalytic performance and stability.

Methane dry reforming: influence of the SiO2 and Al2O3 supports on the catalytic properties of Ni catalysts

The effect of the support nature (SiO2, Al2O3, SiO2–Al2O3) on the catalytic performance of Ni-based catalysts prepared by the incipient wetness method was explored in the dry reforming of methane reaction, and the catalysts were characterized by TG-DTA, SEM-EDX, XRD and UV-VIS methods. The results demonstrate that NiO supported on SiO2-modified Al2O3 exhibits superior catalytic performance in methane dry reforming in the temperature range of 650–700 °C.

Surface control of Ni-Al2O3 dry reforming of methane catalyst by composition segregation

Catalyst surface control is of great importance considering that a catalytic reaction initially starts with surface atoms’ interaction with reactant molecules. In the present study, we synthesized the Ni-Al2O3 dry reforming of methane (DRM) catalyst via the spray-pyrolysis-assisted evaporation-induced self-assembly (EISA) method in order to systematically investigate catalyst surface change as controlled by composition segregation. The present results showed that segregation in the Ni-Al2O3 catalyst had successfully occurred by the post-annealing process and that the segregated Ni nanoparticles were located on the catalyst surface with simultaneous reduction to metal. The size of the surface Ni nanoparticles was highly dependent on the post-annealing temperature, whereas the electronic properties did not consistently align with the trend of particle-size growth, indicating that the particle-growth mechanism underwent alterations from segregation to sintering as the temperature was increased. In other words, when the reduction temperature for metal segregation is excessively high, particle-growth on the external catalyst surface, as induced by post-annealing, is primarily attributable to particle sintering rather than to metal segregation. This phenomenon directly results in decreased Ni surface density. The catalytic DRM reaction revealed that due to sintering, the catalytic performance did not align with the trend of Ni particle-size growth, and the conversion of CH4/CO2 was closely associated with Ni surface density. This information will offer valuable insight to future research focused on development of Ni-based catalysts for DRM reactions.

Study on Ni-based Bead Catalyst for Catalytic Thermal Decomposition of Light Hydrocarbons

Study on Ni-based Bead Catalyst for Catalytic Thermal Decomposition of Light Hydrocarbons

Supercritical ethanol-assisted catalytic upgrading of bio-tar using mesoporous SBA-15 supported Ni-based catalysts

The bio-tar transformation was conducted utilizing Ni-based catalysts supported on mesoporous SBA-15 within a supercritical ethanol environment. This approach aimed to facilitate the synthesis of biofuels and/or value-added chemical compounds, including alkyl phenols and aromatics. The characterization of the catalysts was accomplished by X-ray diffraction (XRD), N2-sorption, temperature programmed reduction (TPR), Transmission electron microscope (TEM), and Fourier Transform Infrared (FT-IR) techniques. Among the examined catalysts, namely SBA-15, Ni/SBA-15, Ni–Mo/SBA-15, and Mg–Ni–Mo/SBA-15, Mg–Ni–Mo/SBA-15 emerged as the catalyst demonstrating the most pronounced activity for the hydrodeoxygenation (HDO) of bio-tar to produce high-quality liquid products (Total Acid Number (TAN): 3.4 mgKOHg−1, oxygen content: 11.0 wt%, Higher heating value (HHV): 36.7 MJkg−1). The effect of reaction temperature (275–350 °C) and time (0–120 min) on the upgrading of bio-tar over Mg–Ni–Mo/SBA-15 was investigated in a one-pot process. The acids, aldehydes, and oxygenated phenols underwent complete conversion into chemically more stable compounds such as aromatics and alkyl phenols at 325 °C for a 120 min holding time. In particular, the oxygenated phenols found in the bio-tar underwent a complete transformation into alkyl phenols within the liquid products.

Salt-Supported Nickel Oxides for Boosted Hydrogen Production: The Critical Role of Halogen.

Hydrogen production from organic waste by gasification and reforming technologies offers major benefits to both the environment and climate. The long-term stability and regeneration of the reforming catalyst are still the biggest challenges because of carbon deposition. Here we report a recyclable salt-supported nickel oxide NiO/NaX (X: F, Cl, Br) catalyst for effective autothermal reforming of the oxygenated volatile organic compound (OVOC) ethyl acetate to hydrogen. The optimal hydrogen selectivity achieved 82.0% at 650 °C and the durability reached 43 h. Interestingly, with the decreasing of halogen electronegativity (F > Cl > Br) in NaX, the corresponding hydrogen selectivity of the catalysts decreased. Although NiO/NaX catalysts possess a very small specific surface area and a dense microstructure, their catalytic performance is better than that of normal Ni-based catalysts loaded on high-specific-surface-area supports. Detailed investigations revealed the critical roles played by halogen during the reforming reaction. First, the strong electronegative halogen in NaX induced the formation of hydrogen bonds with the reactants and reaction intermediates, which may prolong the surface residence time of such species, thus ensuring efficient hydrogen production over small-specific-surface-area catalysts under high-temperature conditions. Second, the halogen of the support NaX weakening the Ni-O bonds of the exposed Ni atoms in NiO/NaX made it easier for NiO to be reduced to Ni0, thus reducing the reaction activation energy and prompting the rapid catalytic reaction. The strength of such metal-support interaction can be easily modulated by varying the halogen electronegativity. This study provides a new prospect for the design of innovative recyclable heterogeneous catalysts with low specific surface area but high activity.

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.

Valorisation of Sub-Products from Pyrolysis of Carbon Fibre-Reinforced Plastic Waste: Catalytic Recovery of Chemicals from Liquid and Gas Phases.

Waste carbon fibre-reinforced plastics were recycled by pyrolysis followed by a thermo-catalytic treatment in order to achieve both fibre and resin recovery. The conventional pyrolysis of this waste produced unusable gas and hazardous liquid streams, which made necessary the treatment of the pyrolysis vapours. In this work, the vapours generated from pyrolysis were valorised thermochemically. The thermal treatment of the pyrolysis vapours was performed at 700 °C, 800 °C and 900 °C, and the catalytic treatment was tested at 700 °C and 800 °C with two Ni-based catalysts, one commercial and one homemade over a non-conventional olivine support. The catalysts were deeply characterised, and both had low surface area (99 m2/g and 4 m2/g, respectively) with low metal dispersion. The thermal treatment of the pyrolysis vapours at 900 °C produced high gas quantity (6.8 wt%) and quality (95.5 vol% syngas) along with lower liquid quantity (13.3 wt%) and low hazardous liquid (92.1 area% water). The Ni-olivine catalyst at the lowest temperature, 700 °C, allowed us to obtain good gas results (100% syngas), but the liquid was not as good (only 58.4 area% was water). On the other hand, the Ni commercial catalyst at 800 °C improved both the gas and liquid phases, producing 6.4 wt% of gas with 93 vol% of syngas and 13.6 wt% of liquid phase with a 97.5 area% of water. The main reaction mechanisms observed in the treatment of pyrolysis vapours were cracking, dry and wet reforming and the Boudouard reaction.

Methanol compared to other fuels for on-board hydrogen production in thermally balanced membrane reactors with internal recycle

New processes for hydrogen production from various sources are required, which will enable decentralized hydrogen utilization. Hydrogen is a challenging energy carrier due to its low volumetric energy density, requiring compression or liquefaction, which are costly steps, reducing the overall energy transformation cycle efficiency. Thus, a hydrogen supply route based on distributed on-demand production is more attractive compared to the traditional centralized production route. In this work we analyze the use of methanol as a hydrogen carrier to be converted to hydrogen in a conceptual autothermal scaled-down system for on-board pure hydrogen production. This system integrates two concentric reactors, membrane separation and heat exchange. The required heat is supplied by catalytic combustion of the reforming effluents which are recycled internally. The temperature profile is controlled by distribution of the combustion feed. A validated mathematical model shows that the thermal efficiency of the hydrogen production process from methanol will be much higher (e.g. 45 % vs 15 % in one case, 60 % vs 30 % in another case) compared to the efficiency obtained when feeding other fuels (methane, ethanol or glycerol). In all cases full conversion of the fuel is obtained. The reason for such a significant intensification is the lack of methane formation in the reforming reactor. This leads to higher driving force for hydrogen transport through the membranes and enables lower operating temperatures, reducing heat losses to the surroundings (which are the main source for efficiency loss). The lack of methane formation is due to the Cu-based catalyst used for methanol reforming, as opposed to the Ni-based catalyst used for reforming of other fuels.

Enhancement of H2 production via catalytic steam gasification of food waste as feedstock and its ash as a support and promoter for Ni catalyst

A novel Ni-based catalyst was prepared with 5% and 10% loading of Ni on food waste ash, and then it was characterized using various physico-chemical methods. Thereafter, the steam gasification experiments were conducted at 850 °C and a steam flow rate (SFR) of 0.75 mL/min in a downdraft fixed bed gasifier. The gasification results showed that a 5% Ni-loaded catalyst was more effective than 10% in enhancing the syngas production with a high hydrogen fraction. It was found that the use of this catalyst increased the syngas yield significantly to 1.8 m3/kg on increasing the catalyst content in feedstock to 50%. Additionally, the hydrogen fraction in syngas increased to 71% which, together with higher syngas yield, increased the hydrogen yield by almost 100%. Furthermore, the performance parameters for gasification, such as carbon conversion efficiency (CCE) and cold gas efficiency (CGE), were also found to be highest at 50% catalyst content of 5% Ni-loaded catalyst in the feedstock.

Nickel-Based Single-Atom Alloys for Methane Dehydrogenation and the Effect of Subsurface Carbon: First-Principles Investigations

Using ab initio calculations, the reaction path for methane dehydrogenation over a series of Ni-based single-atom alloys (Cu, Fe, Pt, Pd, Zn, Al) and the effect that subsurface carbon at the Ni(111) surface has on the reaction barriers are investigated. Due to the well-known problem of coking for Ni-based catalysts, the adsorption and associated physical properties of 0.25 ML, 1.0 ML, and 2 ML of carbon on the Ni(111) surface of various sites are first studied. It is found that the presence of subsurface carbon reduces the stability of the intermediates and increases the reaction barriers, thus reducing the performance of the Ni(111) catalyst. The presence of Al, Zn, and Pt is found to reduce the barriers for the CH4 → CH3 + H and CH3 → CH2 + H (Pt); and CH → C + H (Al, Zn) reactions, while Ni(111) yields the lowest barriers for the CH2 → CH + H reaction. These results thus suggest that doping the Ni surface with both Al or Zn atoms and Pt atoms, functioning as distinct active sites, may bring about an improved reactivity and/or selectivity for methane decomposition. Furthermore, the results show that there can be significant adparticle–adparticle interactions in the simulation cell, which affect the reaction energy diagram and thus highlight the importance of ensuring a common reference energy for all steps.