Nickel Loading Research Articles

A new nanoindentation approach for determining both indentation size effect and continuous apparent activation volume during loading of nanocrystalline Ni and Ni-20 wt.% Fe alloy

A new nanoindentation approach is developed in this study to determine both indentation size effect (ISE) and continuous apparent activation volume () during loading of nanocrystalline nickel (NC Ni) and nanocrystalline nickel-20 wt.% iron alloy (NC Ni-Fe alloy). This approach involves conducting nanoindentation tests under loading modes controlled by both constant strain rate (CSR) and constant loading rate (CLR). Firstly, a new empirical expression for the parameter in the modified Nix-Gao model is established to study the strain rate dependence of the ISEs created in the CSR and CLR tests. Then, continuous data of each individual sample (indentation) during loading are obtained in the CLR test through the alternative use of continuous stiffness measurement technique. The stress dependence of is analyzed based on Duhamel et al.’s model, which considers the role of vacancies generated during inhomogeneous dislocation nucleation. Finally, based on the above experimental and theoretical work as well as transmission electron microscopy observation, the influences of loading mode, loading rate, and material properties (stacking fault energy) on resulting intrinsic hardness of NC Ni and NC Ni-Fe alloy are analyzed. The nanoindentation approach developed in this study provides profound insights into the mechanical behaviors during loading and underlying mechanisms of materials.

Enhanced catalytic performance of ethyl-levulinate to γ-valerolactone: Effect of copper loading on Ni/KIT-5 catalyst

A facile wet impregnation method was employed to prepare a bimetallic Ni–Cu catalyst on a mesoporous KIT-5 support, keeping the nickel loading constant (5 wt%) while varying the copper wt.% (xCu, where x = 8, 10, 12, 14). Several physico-chemical techniques, including X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET) analysis, scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HR-TEM), temperature-programmed desorption of ammonia (NH3-TPD), temperature-programmed reduction of hydrogen (H2-TPR), and X-ray photoelectron spectroscopy (XPS), were utilized for catalyst characterization. An environmentally friendly NiCu bimetallic-supported catalyst system was developed in response to many problems, including metal leaching, sintering, and cost. A mesoporous KIT-5 silica support with a large surface area was used. The hydrogenation of ethyl levulinate to gamma-valerolactone was studied utilizing a high-pressure stirred reactor and a range of reaction temperatures (120–160 °C), hydrogen pressures (10–30 bar), and reaction periods. Various catalysts were used in the investigation. Among all tested catalysts, the 12Cu–5Ni/KIT-5 one shows excellent activity. The best GVL yield is 84% at a conversion of 100% after 8 h of treatment at 150 °C and 25 bar H2 pressure; the promotion is also 76.1%. Optimization of reaction conditions was shown to correlate the physicochemical parameters of the catalyst with its activity.

Microwave-powered integrated carbon capture and utilisation (ICCU) for methane production with rapid temperature response from minimal thermal inertia

Integrated CO2 capture and utilisation (ICCU), emerging as an effective approach for achieving global carbon neutrality goals, demonstrates its potential through the transformation of captured CO2 into valuable methane and the concurrent hydrogen storage via methanation reaction. However, traditional ICCU strategies are heavily reliant on conventional thermal conduction heating, and the in-situ methanation process is constrained by reaction thermodynamics, posing significant challenges. In this study, we introduce for the first time a novel microwave-powered system, employing a clean and efficient energy source that offers rapid heating and on-demand operation and acts as an external field enhancement method in the ICCU-methanation procedure. The designed blend of Ni-loaded CaO and carbon nanotubes (CNTs) integrates the functions of CO2 adsorption, hydrogenation catalysis, and microwave absorbing ability. This novel approach achieved a CO2 capture capacity of 3.31 mmol gDFM-1 with CO2 conversion and CH4 selectivity reaching 71.01 % and 98.17 %, respectively, at a nickel loading of 20 wt%. We also propose a possible rate enhancement mechanism for the microwave-powered ICCU-methanation cyclic process compared to conventional methods. The microwave-powered system can substantially enhance overall efficiency by swiftly responding to temperature swings, thus reducing processing time in ICCU-methanation cycles.

Catalytic hydrothermal liquefaction of Azolla filiculoides into hydrocarbon rich bio-oil over a nickel catalyst in supercritical ethanol

Hydrothermal liquefaction (HTL) is one of the most promising thermochemical techniques for converting wet biomass into crude oil-like products (bio-oil). In this study, Catalytic hydrothermal liquefaction of Azolla filiculoides (AZ) was performed over a various loading of nickel (Ni) on magnesium oxide (MgO) catalyst for the higher and quality bio-oil production. The key operating parameters such as temperature, reaction holding time, amount of Ni on MgO supports catalyst, and reaction solvents were investigated in the presence of a hydrogen environment. There was a 12.8 wt% increase in bio-oil yield and a 6.3 wt% decrease in biochar yield with addition of 15 wt% Ni catalysts compared to the non-catalytic reaction bio-oil yield (44.0 wt%). Results confirmed the highest total bio-oil yield of 56.8 wt% was attained at 280 °C with the catalyst amount of 15 wt% at a residence time of 45 min. Gas chromatography-mass spectrometry (GC-MS), FT-IR, CHNS, TGA, and NMR analyses were performed on the bio-oil, identifying 32.8 % long-chain hydrocarbons (C12-C16) along with small amounts of alcohols, alkanes, and esters. The boiling point distribution revealed that bio-oil produced using the Ni/MgO catalyst contained a significantly higher proportion of diesel-range hydrocarbons (42.4 %). Furthermore, the bio-oil yield under ethanol solvent and Ni catalysts showed higher heating value (HHV) 42.2 MJ/kg. Overall in the presence of Ni hydrogenation efficient catalysts on MgO in the liquefaction reaction promoted the deoxygenation and hydrogenation reaction.

Exploring the superior mild temperature performance of nickel-infused fibrous titania silica for enhanced dry reforming of methane

Carbon (IV) oxide (CO2) and methane (CH4) contribute significantly to greenhouse gas emissions and global warming. One potential approach for reducing their environmental impact is transforming these gases into synthesis gas (CO + H2). This study illustrates the advancement of catalysts supported by fibrous titania silica (FTS), which have nickel loadings of 1%, 3%, and 5%. The FTS support, a modified variant of silica-titania, has a distinct fibrous structure and exhibits mesoporous material properties such as a type IV isotherm and an H1 hysteresis loop. After 72 h of operation, the 1Ni/FTS catalyst converted over 80% of CH4 and CO2 with low coke deposition, outperforming other catalysts. The bare FTS support had reduced CH4 conversion at 600°C, CO2 conversion at 650°C, and H2/CO ratio at 700°C. However, the 5Ni/FTS and 3Ni/FTS catalysts showed consistent increases in CH4 conversion at 600°C. The 1Ni/FTS catalyst, with a pore size of 7.39 nm, had strong metal-support interaction and moderate basicity sites, which helped with reactant dissociation and coke gasification. Despite the slightly higher CH4 conversion of the 3Ni/FTS catalyst and the high basicity of the 5Ni/FTS catalyst, the 1Ni/FTS catalyst demonstrated superior thermal stability and coking resistance, as evidenced by negligible weight loss during TGA analysis. Raman shifts revealed the presence of carbon synthesis and the buildup of disordered amorphous carbon. The Id/Ig ratios of FTS, 1Ni/FTS, 3Ni/FTS, and 5Ni/FTS were 1.01, 0.98, 1.01, and 1.01, respectively. The lower Id/Ig ratio of 1Ni/FTS suggests less disorder. The FTS support promises mild-temperature, carbon-neutral CH4 reforming with long-term catalytic applications. This study demonstrates the efficacy of FTS-supported catalysts in constructing long-term and efficient systems for converting greenhouse gasses.

Synthesis and Characterization of Electrospun Ni-BZY Nano-Fiber Anodes

Solid oxide fuel cell (SOFC) and related Protonic Ceramic Fuel Cell (PCFC) technologies have demonstrated significant promise for the efficient and clean electrochemical conversion of stored energy held in a wide variety of renewable fuels, decreasing dependence on traditional fossil fuels. The high efficiencies of both devices arise from the direct chemical-to-electrical energy transformation, achieved without moving parts and the losses inherent to combustion technologies. As in all fuel cells, electrons are generated via oxidation of fuel at the anode to power an external load before returning to the cathode to reduce an oxidant, usually O2. Separating the two electrodes is a dense, gas-tight, electronically insulating electrolyte that permits ion diffusion to complete the circuit. The SOFC’s solid oxide electrolyte passes oxides from the cathode to the anode, but the large activation barrier associated with this process requires high operating temperatures (≥700 ˚C), exacerbating degradative processes and adding challenges for thermal management. In contrast, the PCFC’s perovskite electrolyte permits protonic diffusion from the anode to the cathode, with a smaller activation barrier leading to lower operating temperatures (450 – 700 ˚C). Despite recent advancements in emerging PCFC materials, the overall efficiency and long-term stability of the device is still impacted in part by the anode’s ability to catalyze fuel oxidation, generate protons, and shuttle electrons to an attached current collector. These processes in turn are strongly linked to the morphology and stability of the anode—often a cermet composed of a Ni catalyst/electronic conductor and protonic ceramic such as yttrium-doped barium zirconate (BZY). In particular, continuity is needed for the Ni, BZY, and pore networks while maximizing boundaries between each phase (three-phase boundary). Traditionally, anodes are fabricated by mixing appropriate powders together without much control over the morphology over the micron-sized components. In this study, we explore an alternative approach to systematically engineer Ni-BZY nanofibers within the anode to enhance overall device performance through improving the underlying electrochemical processes at the anode. Low nickel-content BZY anodes (<40 wt. % Ni) for PCFCs are fabricated through electrospinning, with two distinct methods evaluated for nickel loading. First, uniform BZY nanofibers are synthesized by electrospinning a gel containing BZY metal cations and 5 wt. % Polyvinylpyrrolidone (PVP) as dispersant in ethanol/acetic acid solution followed by sintering at 900°C for 3 h in air, and subsequent electroless deposition of nickel on the fiber surfaces. Second, Ni-BZY is prepared by electrospinning a polymer containing a nickel salt and the same BZY precursors followed by co-sintering at 900°C for 3 h. The Ni-BZY fibers underwent morphological, crystallinity and elemental characterization via SEM, XRD, TEM and Raman microscopy. Initial comparison of the fibers fabricated by both methods has shown that uniform nickel loading of ~35 wt. % on the fibers was achieved in the second method. Slurries containing fibers made from both methods are deposited as anodes onto BZY electrolytes, and the complete cells are tested electrochemically under hydrogen at elevated temperature and compared with a control PCFC constructed using conventional powder materials with comparable nickel loading. In summary, electrospun nanofibers, known for their excellent permeability and faster charge transfer due to their porous structure, present an intriguing alternative for high-performance PCFC anode materials. Figure 1

Nickel nanocatalyst on lanthanum aluminate: Optimizing preparation and evaluating performance in glycerol dry reforming for syngas production

In this study, mesoporous nanocrystalline Ni/La-Al catalysts with varying nickel (Ni) loadings (5, 10, 15, and 20 wt.%) were synthesized using a solid-state method for the glycerol dry reforming (GDR) reaction. The effects of different Ni loadings and the addition of steam on the structural and catalytic performance of the catalysts were investigated. Characterization techniques, including Brunauer-Emmett-Teller (BET) surface area analysis, temperature-programmed reduction (TPR), temperature-programmed oxidation (TPO), and X-ray diffraction (XRD) were employed to analyze the catalysts' properties. Results showed that increasing Ni loading to 10 wt.% improves the catalytic properties. However, by increasing the Ni loading, a decrease in catalytic properties due to increasing particle size, creating NiO bulk phase and surface pore blockage is obvious. A series of experiments were performed to investigate the effect of steam usage on catalytic properties. TPO analysis revealed that steam addition reduces the carbon deposition and shifts oxidation peaks to lower temperatures; consequently, the activity and stability of the catalyst will be enhanced. Although the 5 - 7.5 vol.% of steam in the feed composition significantly stabilizes the catalyst, it is possible to produce H2-rich synthesis gas, and conversely, increasing the temperature reduces the H2/CO ratio. Various examinations were conducted under different conditions, including varying gas hourly space velocity (GHSV), carbon-to-glycerol ratio (CGR), and temperature, to obtain more comprehensive data on the catalysts.

Closing the loop: Biochar-supported nickel catalyst for efficient hydrogen-rich syngas production

Thermochemical conversion of agricultural by-products into hydrogen-rich syngas is a technology that offers both economic and environmental benefits. In this work, we investigated a biochar-supported nickel-based catalyst for the catalytic pyrolysis of straw biomass to produce hydrogen-rich syngas. The by-product, straw biochar, was used as a material for synthesizing fresh catalysts, achieving a closed-loop process. We explored gas yields under various conditions. The highest yields of CO and H2, reaching 0.52 L/g and 0.48 L/g, respectively, were obtained under the conditions of a pyrolysis temperature of 900 °C, a residence time of 20 min, a calcination temperature of 400 °C, a nickel loading of 15 wt%, and a citric acid to potassium hydroxide ratio of 1:4. The catalysts were characterized using XRD, H2-TPR, SEM, and TEM. The results demonstrated that biochar provides excellent support and synergy, enabling the catalyst to function at high temperatures and offering antioxidative protection to the active metals during the thermal process. Overall, this catalytic pyrolysis process, aiming for green and efficient conversion, achieved high yields of syngas and hydrogen.

Zn/Ni catalyst facilitates the oxidation of ethyl lactate to ethyl pyruvate by selective progressions on mesoporous SBA-15 support by a continuous processing approach

The solid-state catalyst-mediated oxidation of alkyl lactate produced from biomass to alkyl pyruvate is an intriguing approach to manufacture valuable resources compounds. In this study, several types of SBA-15/Zn/Ni catalysts containing different nickel loadings have been developed and used in a molecular oxygen environment to oxidize ethyl lactate (EL) compound to ethyl pyruvate (EP). The aforementioned catalyst was comprehensively characterised by employing XRD, ICP, FTIR, N2 physisorption, NH3-TPD, HR-SEM and HR-TEM. As more of nickel was loaded onto the Ni/Zn/SBA-15 catalyst, the EL conversion improved, but the selectivity of EP consistently exceeded greater than 95 %, regardless of the 15 % nickel loading. Assuming maximum conditions for the reaction (90 °C, 2 h in O2) over the Ni/Zn/SBA-15 catalyst, the selectivity of 99.5 % for EP and a conversion of 97.7 % for EL were achieved. A selectivity of 99.5 % for EP and a conversion of 97.7 % for EL were achieved. The catalytic combination of SBA-15 and Zn/Ni exhibited a significant reducing capacity due to the significant connection between both of them, as demonstrated by the NH3-TPD data.

Influence of nickel contents on synthesis gas production over nickel-based catalysts supported by treated activated carbon in dry reforming of methane

This study focuses on the utilization of activated carbon (AC) as a catalyst support after undergoing treatment with HNO3. The treated AC exhibited a microporous structure and a high specific surface area (SBET) of 1483.8 m2 g−1. In this study, supported nickel-based catalysts were synthesized using the wet impregnation method with varying amounts of NiO (2.5, 5, 7.5, 10, 12.5, and 15 wt%). The calcined catalyst samples were then evaluated for their performance in the dry reforming of methane (DRM). Characterization of the catalysts was conducted through FESEM, TPO, H2-TPR, XRD, and N2 adsorption-desorption (BET) analyses. The results revealed that catalytic efficiency increased with an increase in the nickel loading percentage, up to 12.5 wt%. The NiO (12.5)/AC catalyst demonstrated the highest CH4 (60%) and CO2 (68%) conversions and exhibited good stability at 700 °C during 10 h of reaction. Additionally, the catalyst's efficiency decreased with an increase in the calcination temperature from 400 to 600 °C. However, alterations in the CH4/CO2 molar ratio from 0.5 to 1.5 indicated that CH4 and CO2 conversions decreased from 85% to 40% and increased from 63% to 74% at 700 °C, respectively. Moreover, the findings demonstrated that elevating the gas hourly space velocity (GHSV) from 12,000 to 18,000 ml h−1.g−1cat resulted in a decline in catalytic efficiency at a temperature of 700 °C. Moreover, the catalytic efficiency declined with an increase in the reduction temperature from 500 to 600 °C.

Unveiling the catalytic performance of unique core-fibrous shell silica-lanthanum oxide with different nickel loadings for dry reforming of methane

The dry reforming of methane (DRM) stands as a remarkable process for the conversion of methane and carbon dioxide into syngas (H2/CO). In this study, mesoporous fibrous silica lanthanum oxide-supported nickel catalysts (NSLF-x) with various nickel loadings (3 to 15 wt%) were efficiently fabricated using the microemulsion and impregnation approaches, respectively, to conduct DRM. The results obtained from FESEM and TEM revealed the presence of a unique core-fibrous shell-structured morphology of silica lanthanum oxide support (SLF). Furthermore, XRD and SEM-EDS analyses indicated that the structural integrity of SLF remained consistent regardless of the amount of Ni loading, while the size of NiO nanocrystalline varied with the quantity of Ni loading. Notably, H2-TPR analysis emphasized that the NSLF-15 catalyst exhibited the strongest metal-support interaction among the catalysts. Due to this reason, it exhibited outstanding catalytic activity and stability in terms of CO2 conversion (86.7 %), CH4 conversion (87 %), and a high H2/CO ratio at 750 °C, demonstrating high thermal stability after 28 h without any signs of deactivation. The superior catalytic performance of NSLF-15 catalysts, along with their ability to activate CH4 and CO2, can be attributed to the synergistic effects resulting from the enhanced physicochemical properties and the unique morphology. Additionally, the results from TEM, Raman, and TGA analyses also indicated the presence of non-filamentous carbon and filamentous carbons with accumulation of Ni species due to the elevated temperature of the reaction. Overall, the NSLF-15 catalysts hold significant potential for industrial-scale application for syngas formation.

Unveiling the effects of nickel loading on methane dry reforming: Perspectives from ni/fibrous Zeolite-Y catalysts

The development of new technologies that employ greenhouse gases, such as CO2 and CH4, is becoming more important in the fight against global warming. Catalytic methane dry reforming (MDR) is one straightforward way to reduce CO2 and CH4. In this study, the influence of nickel (Ni) loading on the catalytic performance of fibrous zeolite-Y catalysts (Ni/FHY) for MDR was explored. The study involved the synthesis and testing of Ni/FHY with varying Ni loadings (1 wt% to 10 wt%). The results demonstrate that the metal loading significantly affects the catalysts' performance through metal-support interaction. The catalytic activity showed that the performance of FHY increased with optimum metal loading of 5 wt% where the CO2 conversion increased to 90.3% from 82.2%, and CH4 conversion to 94.2% from 79.6%. The findings suggest that the 5 wt% optimal Ni loading showed the critical role of the metal-support interaction in shaping catalytic properties. Hence, this work provides insights into catalyst optimization for sustainable industrial processes, highlights the importance of the synergistic metal-support interaction, and provides insights into the relationship between Ni content and catalytic behavior. Thus, it offers a basis for optimizing catalysts in MDR and contributes to the advancement of sustainable industrial processes.

About the nickel amount deposited on silica-alumina for ethylene production through oxidative dehydrogenation of ethane

This work explores the deposition of different nickel amounts (20 – 80 wt% Ni) on a silica-alumina support to prepare catalysts for ethylene production through the oxidative dehydrogenation of ethane (ODHE). The nickel species features and their distribution on the support had an important effect on their reducibility and interactions, and consequently on their catalytic performance. At low nickel loadings (20 – 40 wt%) highly ethylene-selective formulations were obtained driven by small and well-distributed NiO particles with moderate-to-hard reducibility and high interaction with the support. Contrarily, higher nickel amounts generated bigger NiO aggregates and more reducible Ni2+ species. Therefore, the NiO-support interactions got weakened and ethylene selectivity suffered a slight drop for nickel contents of 50 and 60 wt% and an additional decrease for 80 wt%. Nevertheless, all catalysts maintained a remarkable selectivity to ethylene even with an increased ethane conversion, demonstrating the valuable capacity of this novel support.

Functional Improvement of NiOx/CeO2 Model Catalyst Active in Dry Methane Reforming via Optimization of Nickel Content

The valorization of greenhouse gases, especially when focused on carbon dioxide, currently belongs to the main challenges of pro-environmental chemical processes. One of the important technologies in this field is dry methane reforming (DMR), leading to the so-called synthesis gas (CO + H2). However, to be efficient and economically viable, an active and stable catalyst is required. Ni-based systems can be recommended in this regard. This research aimed to investigate how nickel content can influence the activity of model NiOx/CeO2 catalysts in DMR. A series of NiOx/CeO2 samples of various nickel loadings (0–10 wt.%) were prepared through dry impregnation. The obtained samples were characterized through XRD, RS, N2-BET, DRIFT, SEM, UV/Vis-DR, and XPS. Nonlinear changes in surface properties of the investigated samples with increasing nickel concentration were found. The observed changes are mirrored both in the determined nickel speciation and in the corresponding catalytic activity. The highest activity was found for the catalyst containing 3 wt.%. of nickel.

Engineering biochar-supported nickel catalysts for efficient CO2 methanation

Carbon dioxide methanation is a promising approach to convert captured CO2 into green natural gas. Developing high performance biochar-supported nickel catalysts promotes a circular economy and the application of sustainable catalysts. Western red cedar biochar was produced via pyrolysis at 400, 500, and 600 °C and loaded with nickel via incipient wetness impregnation. Methanation was done at 400, 500, and 600 °C with the highest methane yield of 59% achieved at 500 °C with 10 wt.% Ni loading. This is comparable to a γ-Al2O3 supported catalyst prepared and tested similarly, which achieved a methane yield of 53%. Biochar-supported catalysts showed deactivation whereby methane yield decreased from 59% to 51% over 5 h, likely due to coking and/or the sintering of nickel. Various space velocities were tested, and results demonstrated that with a space velocity of 37.5 mL/g.min methane selectivity was 89% after 1 h on stream compared to methane selectivity of 42%, which was achieved at a space velocity of 112.5 mL/g.min. This shows that a much higher rate of deactivation is observed at higher space velocities. Increasing the nickel loading from 5 wt.% to 10 wt.% increased methane yield from 40% to 58% after 1 h on stream. The higher loading also showed significantly less deactivation. Future work focusing on the extent and impact of metal-support interactions and metal dispersion on catalytic performance and deactivation during CO2 methanation is recommended.

Industrial waste-based Ni-catalysts for ammonia decomposition to produce clean hydrogen

The high mineral containing solid waste materials generated during aluminum production currently lacks any practical application. In this work, the potential of solid waste with/without additional nickel loading (10 to 20 wt%) was investigated as an active catalyst for low temperature ammonia decomposition to produce high purity hydrogen. The X-ray diffraction (XRD) analysis of the samples reveals that iron oxide was the primary component of solid waste with the ability to catalyze the ammonia decomposition reaction. The reducibility, metal support interaction and catalytic activity of the solid waste supported Ni-based catalysts were correlated by the reduction kinetics of the catalysts using temperature-programmed reduction (H2-TPR) data and nucleation/nuclei growth models. Based on the statistical indicators, it was concluded that the random nucleation model describes catalyst reduction adequately. The estimated activation energy for the reduction of the solid waste itself was significantly higher (108.5 kJ/mol) than that of solid waste supported catalyst containing 10 wt% Ni (86.6 kJ/mol). The increase in nickel loading also slightly decreased the activation energy of catalyst reduction, indicating an improvement in the reducibility of the nickel-containing catalysts. These reduction behaviors were also reflected in the ammonia decomposition reaction in a flow reactor. The addition of nickel onto the solid waste resulted in the creation of additional active nickel sites. Consequently, the nickel loaded solid waste supported catalysts exhibited significant improvements in ammonia decomposition activity. Among the three solid waste supported Ni-based catalysts, the catalyst containing 15 wt% Ni displayed the highest activity, that also remained unchanged over extended period, indicating the catalyst stability.

Conversion of Biomass-Derived Tars in a Fluidized Catalytic Post-Gasification Process

The present study deals with the development, characterization, and performance of a Ni-based catalyst over a ceria-doped alumina support as a post-gasification step, in the conversion of biomass-derived tars. The catalysts were prepared using the incipient wetness technique and characterized chemically and physically using NH3-TPD, CO2-TPD, H2-TPR, XRD, Pyridine-FTIR, N2 physisorption, and H2-Pulse Chemisorption. It was observed that the 5 wt% CeO2 reduced the strong and very strong acid sites of the alumina support and helped with the dispersion of nickel. It was noticed that the nickel crystallite sizes and metal dispersion remained unchanged as the nickel loading increased. The performance of the catalysts was studied in a mini-fluidized CREC Riser Simulator at different temperatures and reaction times. The selected tar surrogate was 2-methoxy-4-methylphenol, given its functional group similarities with lignin-derived tars. A H2/CO2 gas blend was used to emulate the syngas at post-gasification conditions. The obtained tar surrogate conversion was higher than 75%, regardless of the reaction conditions. Furthermore, the catalysts used in this research provided an enhancement in the syngas product composition when compared to that observed in the thermal experiments. The presence of hydrocarbons greater than CH4 (C1+) was reduced at 525 °C, from 96 ± 3% with no catalyst, to 85 ± 2% with catalyst and steam, to 68 ± 4% with catalyst and steam-H2/CO2. Thus, the catalyst that we developed promoted tar cracking, tar reforming, and water-gas shift reactions, with a H2/CO ratio higher than 3.8, providing a syngas suitable for alcohol synthesis.

Investigation on the activity of Ni doped Ce0.8Zr0.2O2 for solar thermochemical water splitting combined with partial oxidation of methane

The incredible potential of metal oxide-based two-step solar-driven thermochemical water splitting technology lies in its ability to harness limitless solar energy to produce clean and renewable hydrogen fuel. However, achieving high redox kinetics and lowering the reaction temperature remain the primary challenges in hydrogen production. The CeO2–ZrO2 system is a well-known oxygen carrier for thermochemical water splitting on account of its high temperature stability, quick kinetics, and redox cyclability. While recent studies have explored the combination of methane partial oxidation with metal oxide reduction, the reduction effect of cerium-zirconium oxide is relatively low, and reactivity still needs improvement. The nickel-doped system exhibits good redox performance and is regenerative. In this study, different mass percentages nickel-loaded oxygen carriers mNi/Ce0.8Zr0.2O2 (m = 0, 1, 3, 5, 7, 9) were prepared using the impregnation method. Redox properties of oxygen carriers were investigated in a fixed bed reactor and various characterizations were performed. To assess the durability of mNi/Ce0.8Zr0.2O2, 60 long-cycle experiments were also conducted. The results indicate that the lattice oxygen in mNi/Ce0.8Zr0.2O2 exhibits remarkable selectivity for the partial oxidation of CH4 at temperatures ranging from 880 to 925 °C. The best reactivity performance was achieved with a nickel loading ratio of 5 wt%, and after 60 consecutive redox cycles, 5Ni/Ce0.8Zr0.2O2 demonstrates remarkable robustness, maintaining its redox activity.

Mechanism study of toluene removal using iron/nickel bimetallic catalysts supported on biochar

The present study utilized rice husk biomass as a carrier to synthesize rice husk biochar loaded with iron and nickel. Mono-metallic and bimetallic catalysts were prepared for the removal of toluene as the tar model. The efficiency of the catalysts for the removal of toluene was investigated, and finally, the removal mechanisms of mono-metallic and bimetallic catalysts for toluene were revealed. The experimental results showed that the bimetallic-loaded biochar catalysts had excellent toluene removal performance, which was closely related to the ratio of loaded Fe and Ni. Among them, the catalyst DBC–Fe2.5 %-Ni2.5 % (2.5 wt% iron loading and 2.5 wt% nickel loading) obtained through secondary calcination at 700 °C achieved the highest toluene removal efficiency of 92.76 %. The elements of Fe and Ni in the catalyst were uniformly dispersed on the surface and in the pores of the biochar, and the catalyst had a layered structure with good adsorption. Under the interaction of Fe and Ni, the agglomeration and sintering of Ni were reduced, and the surface acidity of the catalyst was increased, the surface acidity was favorable for toluene removal. The iron‑nickel catalyst did not form significant alloys when calcined at 400 °C, whereas strong metal interactions occurred at 700 °C, resulting in the formation of Fe0.64Ni0.36 alloy and NiFe2O4 alloy. This NiFe alloy had abundant active sites to enhance the catalytic cracking of toluene and provide lattice oxygen for the reaction. Furthermore, the functional groups on the catalyst surface also had an impact on toluene removal. The catalyst prepared in this paper reduces the cost of tar removal, can be applied to the removal of industrial pollutant tars, reduces the pollution of the environment, and provides theoretical guidance and technical reference for the efficient removal of tar.

Enhanced Biomass-Derived Glycerol Conversion to Syngas in the CO2 Reforming Process: Influence of the Nickel Loading Method on Physicochemical Properties and Catalytic Performance

Enhanced Biomass-Derived Glycerol Conversion to Syngas in the CO₂ Reforming Process: Influence of the Nickel Loading Method on Physicochemical Properties and Catalytic Performance