Fabrication of Heterostructural FeNi3-Loaded Perovskite Catalysts by Rapid Plasma for Highly Efficient Photothermal Reverse Water Gas Shift Reaction

Metal-semiconductor heterostructured catalysts have attracted great attention because of their unique interfacial characteristics and superior catalytic performance. Exsolution of nanoparticles is one of the effective and simple ways for in-situ growth of metal nanoparticles embedded in oxide surfaces and their favorable dispersion and stability. However, both high-temperature and a reducing atmosphere are required simultaneously in conventional exsolution, which is time-consuming and costly, and particles often agglomerate during the process. In this work, Ca0.9Ti0.8Ni0.1Fe0.1O3-δ (CTNF) is exposed to dielectric blocking discharge (DBD) plasma at room temperature to fabricate alloying FeNi3 nanoparticles from CTNF perovskite. FeNi3-CTNF has outstanding catalytic activity for photothermal reverse water gas shift reaction (RWGS). At 350 °C under full-spectrum irradiation, the carbon monoxide (CO) yield of FeNi3-CTNF (10.78 mmol g-1 h-1) is 11 times that of pure CaTiO3(CTO), and the CO selectivity is 98.9%. This superior catalytic activity is attributed to the narrow band gap, photogenerated electron migration to alloy particles, and abundant surface oxygen vacancies. The carbene pathway reaction is also investigated through in-situ Raman spectroscopy. The present work presents a straightforward method for the exsolution of nanoalloys in metal-semiconductor heterostructures for photothermal CO2 reduction.

Plasma-Assisted Reforming of Methane

Methane (CH₄ ) is inexpensive, high in heating value, relatively low in carbon footprint compared to coal, and thus a promising energy resource. However, the locations of natural gas production sites are typically far from industrial areas. Therefore, transportation is needed, which could considerably increase the sale price of natural gas. Thus, the development of distributed, clean, affordable processes for the efficient conversion of CH₄ has increasingly attracted people's attention. Among them are plasma technology with the advantages of mild operating conditions, low space need, and quick generation of energetic and chemically active species, which allows the reaction to occur far from the thermodynamic equilibrium and at a reasonable cost. Significant progress in plasma-assisted reforming of methane (PARM) is achieved and reviewed in this paper from the perspectives of reactor development, thermal and nonthermal PARM routes, and catalysis. The factors affecting the conversion of reactants and the selectivity of products are studied. The findings from the past works and the insight into the existing challenges in this work should benefit the further development of reactors, high-performance catalysts, and PARM routes.

Critical assessment of plasma tar reforming during biomass gasification: A review on advancement in plasma technology

The contamination of producer gas with tar due to inefficient removal methods remains a major challenge in the bioenergy industry and a critical barrier, hindering commercial applications of biomass gasification technology. Single syngas treatment through primary and secondary tar removal method is insufficient to produce a tar free syngas. Currently widely applied tar removal methods are catalytic reforming and plasma reforming. Though both methods have hindrances of fast catalyst deactivation due to coke deposition and reduced syngas selectivity with large quantities of undesired liquid products from plasma reforming. Our review paper showed that hybrid plasma catalysis could be a breakthrough in tar reforming methods and overcome major drawbacks. Though, very little work on review articles have reported merging non-thermal plasma and heterogeneous catalyst. Plasma catalysis offers an inexpensive viable future technology of tar reforming through biomass gasification. The article assessed in-depth the synergistic effect created during the interaction of energetic plasma species and catalyst radicals in tar reforming. Review results show that merging plasma with catalysts noticeably Nickel, Non-nickel metal catalyst and zeolites gave pleasant results of tar conversion efficiency, improved gas selectivity and improved catalyst stability.

Metal (Mo, W, Ti) Carbide Catalysts: Synthesis and Application as Alternative Catalysts for Dry Reforming of Hydrocarbons-A Review

Dry reforming of hydrocarbons (DRH) is a pro-environmental method for syngas production. It owes its pro-environmental character to the use of carbon dioxide, which is one of the main greenhouse gases. Currently used nickel catalysts on oxide supports suffer from rapid deactivation due to sintering of active metal particles or the deposition of carbon deposits blocking the flow of gases through the reaction tube. In this view, new alternative catalysts are highly sought after. Transition metal carbides (TMCs) can potentially replace traditional nickel catalysts due to their stability and activity in DR processes. The catalytic activity of carbides results from the synthesis-dependent structural properties of carbides. In this respect, this review presents the most important methods of titanium, molybdenum, and tungsten carbide synthesis and the influence of their properties on activity in catalyzing the reaction of methane with carbon dioxide.

Hydrogen Yield from CO2 Reforming of Methane: Impact of La2O3 Doping on Supported Ni Catalysts

Development of a transition metal based catalyst aiming at concomitant high activity and stability attributed to distinguished catalytic characteristics is considered as the bottleneck for dry reforming of methane (DRM). This work highlights the role of modifying zirconia (ZrO2) and alumina (Al2O3) supported nickel based catalysts using lanthanum oxide (La2O3) varying from 0 to 20 wt% during dry reforming of methane. The mesoporous catalysts with improved BET surface areas, improved dispersion, relatively lower reduction temperatures and enhanced surface basicity are identified after La2O3 doping. These factors have influenced the catalytic activity and higher hydrogen yields are found for La2O3 modified catalysts as compared to base catalysts (5 wt% Ni-ZrO2 and 5 wt% Ni-Al2O3). Post-reaction characterizations such as TGA have showed less coke formation over La2O3 modified samples. Raman spectra indicates decreased graphitization for La2O3 catalysts. The 5Ni-10La2O3-ZrO2 catalyst produced 80% hydrogen yields, 25% more than that of 5Ni-ZrO2. 5Ni-15La2O3-Al2O3 gave 84% hydrogen yields, 8% higher than that of 5Ni-Al2O3. Higher CO2 activity improved the surface carbon oxidation rate. From the study, the extent of La2O3 loading is dependent on the type of oxide support.

Atomically dispersed metal sites stabilized on a nitrogen doped carbon carrier via N2 glow-discharge plasma

A novel, facile and universal N₂ plasma approach to form single atom metal sites (Pt, Pd, Ag, Cu, and Co) is proposed. Fast nucleation and slow growth of metal ions under low temperature plasma are the premise to form single atoms. These isolated metal atoms are subsequently trapped by in situ doped nitrogen. We provide a new route to expand the toolbox of single-atoms preparation.

Large Specific Surface Area Macroporous Nanocast LaFe1−xNixO3: A Stable Catalyst for Catalytic Methane Dry Reforming

Macroporous nanocast perovskites, LaFe1−xNixO3 (x = 0.3, 0.5, and 0.7), were synthesized by using a nanocasting technique with SBA-15 as a template and applied to methane dry reforming (MDR). The prepared catalysts were characterized by X-ray diffraction, transmission electron microscopy, specific-surface-area analysis, hydrogen temperature-programmed reduction, and thermogravimetric analysis. LaFe1−xNixO3 revealed a large specific surface area, which could enhance its catalytic activity. The catalysts were reduced to Ni/LaFeO3-La2O3 in the MDR reaction. The alkaline additive, La2O3, and perovskite oxide, LaFeO3, strongly interacted with the active component to reduce the surface energy of metal particles and prevent aggregation of active Ni. The results showed that LaFe0.5Ni0.5O3 and LaFe0.3Ni0.7O3 perform better than LaFe0.7Ni0.3O3. More importantly, LaFe0.5Ni0.5O3 had a very long lifetime (>80 h) in the MDR reaction. The LaFe0.5Ni0.5O3 catalyst showed excellent stability in the MDR reaction and has potential use in industrial applications.

Highly Dispersed Co Nanoparticles Prepared by an Improved Method for Plasma-Driven NH3 Decomposition to Produce H2

Previous studies reveal that combining non-thermal plasma with cheap metal catalysts achieved a significant synergy of enhancing performance of NH3 decomposition, and this synergy strongly depended on the properties of the catalyst used. In this study, techniques of vacuum-freeze drying and plasma calcination were employed to improve the conventional preparation method of catalyst, aiming to enhance the activity of plasma-catalytic NH3 decomposition. Compared with the activity of the catalyst prepared by a conventional method, the conversion of NH3 significantly increased by 47% when Co/fumed SiO2 was prepared by the improved method, and the energy efficiency of H2 production increased from 2.3 to 5.7 mol(kW·h)−1 as well. So far, the highest energy efficiency of H2 formation of 15.9 mol(kW·h)−1 was achieved on improved prepared Co/fumed SiO2 with 98.0% ammonia conversion at the optimal conditions. The improved preparation method enables cobalt species to be highly dispersed on fumed SiO2 support, which creates more active sites. Besides, interaction of Co with fumed SiO2 and acidity of the catalyst were strengthened according to results of H2-TPR and NH3-probe experiments, respectively. These results demonstrate that employing vacuum-freeze drying and plasma calcination during catalyst preparation is an effective approach to manipulate the properties of catalyst, and enables the catalyst to display high activity towards plasma-catalytic NH3 decomposition to produce H2.

Sc promoted and aerogel confined Ni catalysts for coking-resistant dry reforming of methane

Sc promoted and aerogel confined Ni catalysts were developed for coking-resistant dry reforming of methane.

Catalytic hydrodeoxygenation of anisole over nickel supported on plasma treated alumina–silica mixed oxides

Hydrodeoxygenation (HDO) of anisole, a representative of lignin-derived bio oil, was investigated on plasma treated SiO₂–Al₂O₃ supported Ni nanocatalyst at low hydrogen pressure.

Promotion effects of plasma treatment on silica supports and catalyst precursors for cobalt Fischer–Tropsch catalysts

Glow discharge plasma would modify the surface hydrophilicity of support; the plasma treated catalysts showed much higher FTS activity.

Supported Ni catalyst on a natural halloysite derived silica–alumina composite oxide with unexpected coke-resistant stability for steam-CO2 dual reforming of methane

This work presents a facile and scalable approach for preparing robust supported Ni catalyst with unexpected catalytic stability with outstanding coke deposition and Ni-sintering resistance for steam-CO₂ dual reforming of methane to produce syngas.

Effect of a second metal (Co, Cu, Mn or Zr) on nickel catalysts derived from hydrotalcites for the carbon dioxide reforming of methane

NiCo and NiCu catalysts exhibited enhanced stability compared with a Ni catalyst for the dry reforming of methane. On the contrary, NiMn and NiZr catalysts decreased the reforming stability.

Bayberry-like ZnO/MFI zeolite as high performance methanol-to-aromatics catalyst

A unique bayberry-shaped MFI zeolite structure with a zeolite shell (1–1.5 μm in thickness) and numerous zeolite nanowires (500–800 nm in length) vertically grown on two sides of the shell is prepared. The catalytic efficiency is significantly higher than that of the conventional ZnO/MFI zeolite.

Ni-based catalyst derived from Ni/Al hydrotalcite-like compounds by the urea hydrolysis method for CO methanation

The catalytic methanation of CO was investigated at atmospheric pressure over Ni-based catalysts derived from Ni/Al hydrotalcite-like compounds.

Ordered mesoporous alumina-supported bimetallic Pd–Ni catalysts for methane dry reforming reaction

To compare the influence of Pd addition to Ni supported on ordered mesoporous alumina catalyst, prepared highly ordered mesoporous alumina (MA) was used as catalyst support for methane dry reforming under atmospheric pressure.

Nanoparticles-in-concavities as efficient nanocatalysts for carbon dioxide reforming of methane to hydrogen and syngas

The ceria concavity-loaded Ni nanoparticle catalysts can lead to more active sites and promote CO₂ dissociative activation and CO desorption, thus enhancing significantly the catalytic performances for methane dry reforming with CO₂.

Crystal-plane effect of nanoscale CeO2 on the catalytic performance of Ni/CeO2 catalysts for methane dry reforming

The morphology and crystal-plane effects of CeO₂ materials (nanorods, nanocubes, nanooctas and nanoparticles) on the catalytic performance of Ni/CeO₂ in methane dry reforming were investigated.

Progress in Synthesis of Highly Active and Stable Nickel-Based Catalysts for Carbon Dioxide Reforming of Methane

In recent decades, rising anthropogenic greenhouse gas emissions (mainly CO2 and CH4 ) have increased alarm due to escalating effects of global warming. The dry carbon dioxide reforming of methane (DRM) reaction is a sustainable way to utilize these notorious greenhouse gases. This paper presents a review of recent progress in the development of nickel-based catalysts for the DRM reaction. The enviable low cost and wide availability of nickel compared with noble metals is the main reason for persistent research efforts in optimizing the synthesis of nickel-based catalysts. Important catalyst features for the rational design of a coke-resistant nickel-based nanocatalyst for the DRM reaction are also discussed. In addition, several innovative developments based on salient features for the stabilization of nickel nanocatalysts through various means (which include functionalization with precursors, synthesis by plasma treatment, stabilization/confinement on mesoporous/microporous/carbon supports, and the formation of metal oxides) are highlighted. The final part of this review covers major issues and proposed improvement strategies pertaining to the rational design of nickel-based catalysts with high activity and stability for the DRM reaction.

In situ controllable assembly of layered-double-hydroxide-based nickel nanocatalysts for carbon dioxide reforming of methane

The dual confinement effects from alumina and LDH precursors produced a new nanoplates-on-pore structure with a uniform distribution and smaller size of Ni nanoparticles (NPs) for the LDOs/γ-Al₂O₃, while enhanced catalytic performance and better resistance to sintering and coking.

Synthesis of tungsten carbide nanoparticles in biochar matrix as a catalyst for dry reforming of methane to syngas

Tungsten carbide (WC) nanoparticles were synthesized by carbothermal reduction (CR) of tungsten-promoted biochar.

Synthesis of AuPd alloyed nanoparticles via room-temperature electron reduction with argon glow discharge as electron source

Argon glow discharge has been employed as a cheap, environmentally friendly, and convenient electron source for simultaneous reduction of HAuCl4 and PdCl2 on the anodic aluminum oxide (AAO) substrate. The thermal imaging confirms that the synthesis is operated at room temperature. The reduction is conducted with a short time (30 min) under the pressure of approximately 100 Pa. This room-temperature electron reduction operates in a dry way and requires neither hydrogen nor extra heating nor chemical reducing agent. The analyses using X-ray photoelectron spectroscopy (XPS) confirm all the metallic ions have been reduced. The characterization with X-ray diffraction (XRD) and high-resolution transmission electron microscopy (HRTEM) shows that AuPd alloyed nanoparticles are formed. There also exist some highly dispersed Au and Pd monometallic particles that cannot be detected by XRD and transmission electron microscopy (TEM) because of their small particle sizes. The observed AuPd alloyed nanoparticles are spherical with an average size of 14 nm. No core-shell structure can be observed. The room-temperature electron reduction can be operated in a larger scale. It is an easy way for the synthesis of AuPd alloyed nanoparticles.

Facile synthesis of hollow hierarchical Ni/γ-Al2O3 nanocomposites for methane dry reforming catalysis

Hierarchical Ni/Al₂O₃ nanocomposite possesses a high surface area, high loading of well dispersed metal nanoparticles, and a hierarchical hollow structure. The strong interaction between metal and support and the large open accessible surface lead to excellent sintering and carbon resistance, and superior catalytic performance in methane dry reforming.

Immobilizing Ni nanoparticles to mesoporous silica with size and location control via a polyol-assisted route for coking- and sintering-resistant dry reforming of methane

Highly dispersed Ni nanoparticles in mesoporous silica were achieved via using polyol as new delivery conveyors and removable carbon templates.