Nickel Oxide Catalyst Research Articles

Enhanced CO2 Methanation over Nickel‐Based Unsupported Catalyst Synthesized by Chemical Precipitation Method

AbstractThis study investigated the catalytic CO2 methanation using nickel oxide (NiO) nanoparticles and nickel oxalate (NiC2O4) as catalysts. The NiC2O4 precursor was synthesized through a chemical precipitation reaction between nickel (II) nitrate hexahydrate (Ni(NO3)2.6H2O) and oxalic acid (H2C2O4.2H2O). Nickel oxide (NiO) nanoparticles were synthesized through thermal decomposition of NiC2O4 precursor at 450 °C in air. The samples were characterized by XRD, FTIR, BET, SEM, and EDX. The XRD and FTIR analyses revealed that the NiO nanoparticles were well‐crystallized having size 17.30 nm. The BET analysis of the NiO sample revealed mesoporous NiO nanoparticles with a specific surface area (SBET) of 29.08 m2/g and a narrow distribution of pore sizes. The catalytic performance of NiO and NiC2O4 catalysts studied for the CO2 methanation in tubular packed bed reactor at 150–550 °C and 1 atm. The reduced NiO nanoparticles exhibited more catalytic activity than the decomposed NiC2O4 catalyst. At 380 °C, 1 atm, and gas hourly space velocity (GHSV) of 9000 mL g−1 h−1, the reduced NiO nanoparticle catalyst showed high catalytic activity, with a maximum CO2 conversion of 85.54 %, 99 % CH4 selectivity, and 84.69 % CH4 yield. Furthermore, the NiO nanoparticle catalyst demonstrated excellent stability after 12 h of streaming at 380 °C.

Biodiesel Prepared Through Silver Doped Blended Heterogeneous Catalyst and Soybean Oil

Biodiesel amalgamate with silver doped nickel and calcium blended oxide catalyst & soybean oil. Alkaline earth metal calcium and the use of nickel blended oxide integrated and optimized throughout a blending process that after silver doped in differing percentages to research the outcome of prepared catalysts on the change oil to FAME. Catalytic characteristics such as surface area, energy band difference, crystallinity, morphology, and the composition of prepared samples explored utilizing different BET, FTIR, XRD, SEM, and EDX methods. Silver doped 20 percent NiO-CaO blended oxide catalyst defined with a distinctive weight percentage of silver 2wt percent Ag found to be most viable with 80 percent transformation of oil. The optimized response variable for the change of biodiesel was alcohol to oil proportion 15:1, response temperature 64oC, and catalytic converter stacking 05wt percent. This prepared catalyst has added significance as a blended catalyst for biodiesel generation. Key Words: FAME, Transesterification, Silver, Mixed Oxide, Catalyst

Aromatic rich biofuel production via catalytic co‐pyrolysis of paulownia wood and polypropylene waste

AbstractThermo‐catalytic co‐pyrolysis of paulownia wood and polypropylene mixture were carried out in a fixed bed horizontal reactor system. The biochar obtained from pyrolysis of paulownia wood was activated by steam at 700°C. Activated biochar supported magnesium oxide, nickel oxide and cobalt oxide catalysts were prepared by incipient miosture impregnation and were used to upgrade the bio‐oil. Catalytic pyrolysis reduced the amount of bio‐oil compared with non‐catalytic pyrolysis (59.5% of bio‐oil). The results indicate that the production of aromatic compounds increased from 40.35% to 65.93, 62.12 and 61.56% using Ni, Co and Mg catalysts, respectively. For all three catalysts, the production of furan compounds decreased. It was found that bio‐char based catalysts are suitable for use in the co‐pyrolysis process to improvement the biofuel production.

Roles of different Ni-Si interactions in methane combustion under oscillating temperature conditions

The silicon- modified nickel oxide catalysts with the same compositions but distinct Ni-Si interactions were obtained via different synthesis routes and utilized for methane combustion under conditions of oscillating temperatures. For catalysts prepared by co-grinding, amorphous SiO2 was dispersed on the surface of large NiO crystallites. During high-temperature calcination or reactions, the crystallization of SiO2, coupled with the sintering or decomposition of NiO crystallites, led to the inferior catalytic activity and stability. Interactions between Ni and Si species were enhanced in catalysts synthesized by precipitation. The Si species was incorporated into the NiO lattice to inhibit the growth of NiO crystallites and to generate nickel silicate species under thermal treatments. The small NiO crystallites provided more Ni3+ and active oxygen species for methane activation and oxidation, while the bulk nickel silicate species played a pivotal role in improving thermal stability, conjointly provoking excellent catalytic performance in cyclic heating–cooling tests between 180 and 800 °C. This study offers new insights into the design of metal oxide composites for catalytic applications.

Potential of nickel oxide catalyst from banana peel extract via green synthesis method in both photocatalytic reduction of methylene blue and generation of hydrogen from sodium borohydride hydrolysis

In the present work, nickel oxide (NiO) catalyst was prepared using banana peel extract as a stabilizing agent via the green synthesis method. Scanning electron microscopy (SEM), energy dispersive spectroscopy (EDX), X-ray diffraction (XRD), transmission electron microscopy (TEM) and ultraviolet spectroscopy (UV) analyses were carried out to investigate the structural and textural characteristics of the NiO catalyst. According to the XRD and TEM results, the particle size of the NiO catalyst was found to be in the range of 20–80 nm. From the EDX analysis, it was concluded that the NiO catalyst was synthesised in pure form. The potential of the NiO catalyst was tested for the first time in both the photocatalytic reduction of methylene blue (MB) and the generation of hydrogen (H2) from sodium borohydride (NaBH4) hydrolysis. A high decolorization efficiency of 98.09 % and a reuse efficiency of 90.89 % after five recycles were achieved for the photocatalytic reduction of MB using NiO catalyst. The photocatalytic reduction of MB was consistent with the pseudo-first order kinetic model, and the reaction rate constant was found to be 2.55 min−1. The H2 generation rate (RH2) of 922.5 mLH2 min−1 gcat−1 at 70 °C was achieved for the NaBH4 hydrolysis. The kinetics of H2 generation from NaBH4 hydrolysis was studied employing the nth-order and the Langmuir-Hinshelwood models, and the activation energy (Ea) values were found to be 21.29 kJ mol−1 and 22.23 kJ mol−1, respectively. It was concluded that the NiO catalyst prepared by the eco-friendly green synthesis method has a promising potential in both photocatalytic reduction of MB and H2 generation from NaBH4 hydrolysis.

Activation of Nickel Oxide Catalysts Modified with Cobalt, Cerium, Manganese, and Zirconium

Activation of Nickel Oxide Catalysts Modified with Cobalt, Cerium, Manganese, and Zirconium

Role of Cr-doped NiO in reduction under a low concentration of H2 and CO

Nickel-chromium alloys are often utilized in high-resistance and heating metamaterials because of their passivity; however, their reducibility behavior has never been reported. Herein, Ni-Cr reduction has been conducted in H2 and CO atmospheres. Nickel oxide (NiO) catalysts were impregnated with chromium and subsequently subjected to temperature-programmed reduction (TPR) at low concentrations of CO and H2 to determine their reduction performance. The TPR profile fitting using a Gaussian function indicated the Cr-NiO reduction transformation of Cr6+→Cr3+ at temperatures below ∼300 °C for both reductant gasses. Furthermore, the addition of Cr shifted the reduction peaks to a lower temperature owing to the interaction of Cr and Ni atoms, leading to increased reducibility. The characterizations of the Cr-NiO catalyst using X-ray diffraction, Brunauer–Emmet–Teller surface area, scanning electron microscopy, and X-ray photoelectron spectroscopy (XPS) analyses demonstrated the formation of NiCrxOy alloy with increasing surface area and porosity. The kinetic analysis using the Kissinger method demonstrated the reducibility of the catalysts with a low Ea value after the addition of Cr, where an Ea value of 68.0 kJ mol−1 (NiO) decreased to 49.3 kJ mol−1 (Cr-NiO) in the H2 atmosphere and an Ea value of 95.8 kJ mol−1 (NiO) decreased to 91.9 kJ mol−1 (Cr-NiO) in the CO atmosphere. The synergistic effects between Cr and Ni contributed to the increase in catalyst active sites by the transformation of the nickel oxidation state, which demonstrated the formation of oxygen vacancies and alloys, as proven via XPS analysis.

Enhancing Catalytic Performance with Sol‐Gel Hydrotalcite‐Derived Nickel Oxide Catalysts for Dry Reforming of Methane: An Examination on Reactivity and Coke Formation

AbstractHydrotalcite‐based materials are preferred as catalysts due to their versatility and easiness of their synthesis. This work studies supported nickel catalysts made from hydrotalcites through sol‐gel synthesis, Ni‐EDTA impregnation, and coprecipitation. The synthetized hydrotalcites present nanocapsular morphology and dispersed nickel nano‐oxide particles after calcination at 500 °C. The catalysts were evaluated at 600 °C and 800 °C for 8 hours and demonstrated high conversions and varying yields, with sol‐gel oxide catalysts (SgOxMix) showing the best performance with the highest reactivity and controlled coke formation at 800 °C after 14 hours of testing. The mixed oxide morphology promotes electronic effects and inhibits carbon encapsulation of metallic particles. Principal component analysis was performed to explain fluctuations in the reaction pathway.

Effect of Transition Metals Addition on the Nickel Oxide Catalyst toward Reduction Behaviour in Carbon Monoxide Atmosphere

The chemical reduction progression behaviour of transition metals (Mo, Zr, W, Ce, and Co) doped on NiO was studied using temperature programmed reduction (TPR) analysis. A wet impregnation method was applied to synthesise the doped NiO series catalysts. The reduction progress of the catalysts was attained by using a reductant gas at the concentration of 40% v/v CO/N2. X-ray diffraction (XRD) was employed to determine the composition of the reduced phases. Undoped NiO was reduced at 384℃ to obtain a cubic phase of NiO. It was observed that Ce/NiO exhibited the lowest reduction temperature of 370℃ among all catalysts. This phenomenon might be due to a higher surface area of Ce/NiO compared to undoped NiO, which facilitated a faster reduction reaction. The rest of the doped NiO series catalysts (Co/NiO, Mo/NiO, W/NiO and Zr/NiO) demonstrated a higher reduction temperature compared to undoped NiO. New peaks in the XRD pattern were observed only for the reduced catalysts of Mo/NiO and W/NiO, which were associated with monoclinic MoO2 and WO2.72 phases, respectively. The formation of new compounds or more stable nickel alloys led to a slower reduction reaction than undoped NiO. Therefore, Ce/NiO was the most efficient catalyst in promoting the formation of Ni under the CO atmosphere.

Use of Nickel Oxide Catalysts (Bunsenites) for In-Situ Hydrothermal Upgrading Process of Heavy Oil.

In this study, Nickel oxide-based catalysts (NixOx) were synthesized and used for the in-situ upgrading process of heavy crude oil (viscosity 2157 mPa·s, and API gravity of 14.1° at 25 °C) in aquathermolysis conditions for viscosity reduction and heavy oil recovery. All characterizations of the obtained nanoparticles catalysts (NixOx) were performed through Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), Atomic Force Microscopy (AFM), X-Ray and Diffraction (XRD), and ASAP 2400 analyzer from Micromeritics (USA), methods. Experiments of catalytic and non-catalytic upgrading processes were carried out in a discontinuous reactor at a temperature of 300 °C and 72 bars for 24 h and 2% of catalyst ratio to the total weight of heavy crude oil. XRD analysis revealed that the use of nanoparticles of NiO significantly participated in the upgrading processes (by desulfurization) where different activated form catalysts were observed, such as α-NiS, β-NiS, Ni3S4, Ni9S8, and NiO. The results of viscosity analysis, elemental analysis, and 13C NMR analysis revealed that the viscosity of heavy crude oil decreased from 2157 to 800 mPa·s, heteroatoms removal from heavy oil ranged from S-4.28% to 3.32% and N-0.40% to 0.37%, and total content of fractions (ΣC8-C25) increased from 59.56% to a maximum of 72.21%, with catalyst-3 thank to isomerization of normal and cyclo-alkanes and dealkylation of lateral chains of aromatics structures, respectively. Moreover, the obtained nanoparticles showed good selectivity, promoting in-situ hydrogenation-dehydrogenation reactions, and hydrogen redistribution over carbons (H/C) is improved, ranging from 1.48 to a maximum of 1.77 in sample catalyst-3. On the other hand, the use of nanoparticle catalysts have also impacted the hydrogen production, where the H2/CO provided from the water gas shift reaction has increased. Nickel oxide catalysts have the potential for in-situ hydrothermal upgrading of heavy crude oil because of their great potential to catalyze the aquathermolysis reactions in the presence of steam.

Predicting the catalytic performance of Nb-doped nickel oxide catalysts for the oxidative dehydrogenation of ethane by knowing their electrochemical properties

In the present article, a relationship between the catalytic performance in the oxidative dehydrogenation of ethane (ODHE) for Nb-doped NiO catalysts and their electrochemical properties has been proposed. To do so, highly stable and selective Nb-doped NiO catalysts for the ODHE to ethylene have been synthesized by optimizing synthesis parameters such as the amount of oxalic acid in the synthesis gel and the calcination temperature. These catalysts have been characterized by means of XRD, HRTEM, Raman and UV–vis diffuse reflectance spectroscopies, TPR and XPS. Moreover, Electrochemical Impedance Spectroscopy (EIS), capacitance measurements (Mott-Schottky analysis) and cyclic voltammetries studies were also carried out. Electrochemical characterization indicates changes in the type of semiconductivity: p-type for samples calcined at 350 °C and the sample prepared in the absence of oxalic acid and calcined at 500 °C, to n-type for samples prepared in the presence of oxalic acid in the synthesis gel and calcined at 500 °C. According to the obtained results, the most selective catalysts present a low Nb-incorporation on the NiO lattice with a large amount of tiny Nb2O5 nanoparticles covering NiO crystallites. This work presents, for the first time, a complete electrochemical characterization of Nb-doped NiO catalysts showing a correlation between electrochemical properties and catalytic performance.

Determining surface-specific Hubbard-U corrections and identifying key adsorbates on nickel and cobalt oxide catalyst surfaces.

NiO is a popular transition metal oxide (TMO) with high thermal and chemical stability and Co3O4 is a relatively more reducible TMO due to weaker metal-oxygen bonds. Both are often used as catalysts in a variety of chemical transformations. Density functional theory (DFT) and X-ray photoelectron spectroscopy (XPS) are used to investigate catalysis on TMO surfaces, yet both techniques have their own limitations. The accuracy of DFT highly depends on the choice of Hubbard U correction. The bulk-property optimized U value of 5.3 eV for NiO and different U values for Co3O4, without any consensus, are often used in the literature to simulate surface catalysis. However, U values optimized using bulk properties often fail to reproduce surface-adsorbate interactions on TMOs. Similarly, there exists arbitrariness in assigning observed XPS shifts to different surface species on these metal oxides. Hence, a synergistic application of XPS and DFT+U is implemented to determine the surface specific U values for NiO and Co3O4, and to identify adsorbed surface moieties corresponding to experimentally observed XPS shifts. For the NiO (100) surface, the U value of ∼2 eV is able to reproduce the experimentally observed XPS O1s core level binding energy shifts correctly, instead of the bulk property optimized and commonly used U value of 5.3 eV. Using this surface specific U value of 2 eV, the experimentally observed XPS shifts are assigned. Similarly, for Co3O4 (100) surface, ∼3 eV of U value could successfully predict the experimentally observed XPS shifts and corresponding adsorbates. The surface adsorbates and configurations suggested in this work will help analyze experimental XPS data and the surface specific U values will ensure accurate predictions of adsorption and reaction energetics on these catalysts.

Improved activity for the oxygen evolution reaction using a tiara-like thiolate-protected nickel nanocluster.

Practical electrochemical water splitting and carbon-dioxide reduction are desirable for a sustainable energy society. In particular, facilitating the oxygen evolution reaction (OER, the reaction at the anode) will increase the efficiency of these reactions. Nickel (Ni) compounds are excellent OER catalysts under basic conditions, and atomically precise Ni clusters have been actively studied to understand their complex reaction mechanisms. In this study, we evaluated the geometric/electronic structure of tiara-like metal nanoclusters [Nin(PET)2n; n = 4, 5, 6, where PET refers to phenylethanethiolate] with the same SR ligand. The geometric structure of Ni5(SR)10 was determined for the first time using single-crystal X-ray diffraction. Additionally, combined electrochemical measurements and X-ray absorption fine structure measurements revealed that Ni5(SR)10 easily forms an OER intermediate and therefore exhibits a high specific activity.

Influence of NiO ALD Coatings on the Field Emission Characteristic of CNT Arrays.

The paper presents a study of a large-area field emitter based on a composite of vertically aligned carbon nanotubes covered with a continuous and conformal layer of nickel oxide by the atomic layer deposition method. The arrays of carbon nanotubes were grown by direct current plasma-enhanced chemical vapor deposition on a pure Si substrate using a nickel oxide catalyst which was also deposited by atomic layer deposition. The emission characteristics of an array of pure vertically oriented carbon nanotubes with a structure identical in morphology, covered with a layer of thin nickel oxide, are compared using the data from a unique computerized field emission projector. The deposition of an oxide coating favorably affected the emission current fluctuations, reducing them from 40% to 15% for a pristine carbon nanotube and carbon nanotube/nickel oxide, respectively. However, the 7.5 nm nickel oxide layer coating leads to an increase in the turn-on field from 6.2 to 9.7 V/µm.

Highly-stable, bifunctional, binder-free & stand-alone photoelectrode (FexNi1-xO@a-CC) for natural waters splitting into hydrogen

Photoelectrochemical (PEC) water splitting is a promising approach to boost green hydrogen production. Herein, we prepared novel binder-free photoelectrode by direct growth of iron doped nickel oxide catalyst over activated carbon cloth (FexNi1-xO@a-CC) having band gap energy of 2.2 eV for overall water splitting. FexNi1-xO@a-CC photoelectrode had shown remarkable lower potential of only 1.36 V for oxygen evolution reaction (OER) to reach 10 mA cm−2 current density using very low photonic intensity of 8.36 × 10−4 E/L.s. For the first time, we also reported electrical efficiency required for PEC water splitting for 1 m3 of water that is equal to 0.09 kWh/m3. FexNi1-xO@a-CC photoelectrode also exhibits low potentials of 1.44 V (OER) and −0.210 V (HER) at 10 mA cm−2 to split sea water. Our results confirmed that designing FexNi1-xO@a-CC photoelectrode would be an innovative step to widen green energy conversion applications using natural waters (both sea and fresh water).

NiO ELECTRO-DEPOSITION TECHNIQUE OF γ-Al2O3 WASHCOAT ON FeCrAl SUBSTRATE BY USING SULPHAMATE TYPE SOLUTION

Electro-deposition process to develop surface layer on the substrate material in Catalytic converter (CATCO) become interesting area due to that process was purposed to improve the physical properties of substrate material. Currently, precious metals such as Platinum (Pt), Palladium (Pd), and Rodium (Rd) were used due to excellent oxidation resistant but it limited and easily oxidized. Therefore, Nickel Oxide (NiO) catalyst used as electro-deposition material. NiO electro-deposition technique that called by EL was conducted by using NiO as cathode and FeCrAl as substrate and -Al2O3 as washcoat material. This technique was performed by variation times of 15, 30, 45, 60 and 75 minutes, current density of 8 A/dm2. The results shows that Coating layer of NiO and -Al2O3 has been developed on surface of FeCrAl substrate. The coating layer was increase the surface roughness which showed by surface morphology data that coated FeCrAl substrate has uneven surface and some particles has been embedded on that surface. The composition of raw material was consists of Fe for 74.13wt%, Cr of 20.25 wt% and Al of 5.62 wt%. Meanwhile, for composition of EL samples was 52.56- 63.54wt% for Fe element, Al for 3.56-11.89 wt%, Cr for 14.97-18.56 wt%, O for 2.47-11.78 wt%, C for 8.33-11.85 wt%, Na for 0.11-0.48 wt% and Ni for 0.17- 1.58 wt%. Higher elements of the EL samples potential to improve the thermal stability at high temperature due to CATCO operate at high temperature of 600-8500C and in extreme condition.

NiO Supported on Porous Carbon From Merbau Wood: Synthesis and Characterization

Nickel oxide catalyst supported on porous carbon (NiO/C), the materials support were synthesized from Merbau wood. The metals were loaded onto the carbon by the wet impregnation method. After drying and calcination, NiO/C was obtained. The prepared catalyst was evaluated for the hydrocracking of pyrolyzed α-cellulose. The catalyst was characterized by XRD, SEM-EDX, FT IR, SAA, and acidity test by NH3 base vapor adsorption determined gravimetrically and by FT IR. The XRD results showed that the carbonaceous of materials support were amorphous materials that characteristic for mesopore carbon. The impregnation of nickel into carbon results in difraktogram peaks that correspond to the presence of NiO, which was confirmed by EDX. The SEM image showed that the morphology of the catalyst samples was a honeycomb-like structure. The acidity test showed that the total acid amount of NiO/C samples was 3.05 mol/g, and the FT IR spectra indicated that there were Brönsted and Lewis acid sites on NiO/C catalyst. The SAA results showed that the specific surface area, total pore volume, and average pore diameter of the NiO/C catalyst were 520.41 m2/g, 0.27 cm3/g, and 2.083 nm, respectively.

Multi-walled carbon nanotubes growth by chemical vapour deposition: Effect of precursor flowing path and catalyst size

Carbon nanomaterials have been found to have promising performance in various applications. However, the complexity and high operation cost during the fabrication still limit the mass production. In this study, multi-walled carbon nanotubes (MWCNTs) were grown on nickel oxide (NiO) via chemical vapour deposition (CVD) with ethanol as the carbon precursor. The NiO catalyst was fabricated from a nickel nitrate – ethanol mixture. The particle size of NiO was altered through high-energy ball milling for 0, 4, and 7 h. The influence of precursor flowing path (D) and NiO catalyst size during the MWCNTs growth have been investigated. The Raman spectra showed that the crystallite size of MWCNTs (L a ) increased from 16.97 to 18.00 nm as the NiO milling time increased. Furthermore, NiO-catalysed MWCNTs at D = 12 cm achieved the highest carbon yield (80.54%), with an I D /I G ratio of 1.134. Also, SEM and TEM revealed that the larger size of NiO catalyst produced fewer layers of MWCNTs. These findings are significant to aid researchers and manufacturers in optimising the CVD process towards large-scale MWCNTs fabrication.

Catalytic Cracking of Crude Biodiesel into Biohydrocarbon Using Natural Zeolite Impregnated Nickel Oxide Catalyst

Crude biodiesel is biodiesel that still contains impurities. A catalytic can improve the quality of biohydrocarbons (biogasoline, biokerosene, and green diesel). The catalyst used is nickel oxide impregnated natural zeolite (NiO/Zeolite). The use of nickel can increase the activity of the catalyst because it has an empty d orbital and a smaller molecular size. This study aims to determine the best catalyst that can exhibit the greatest selectivity toward biohydrocarbons. Natural zeolite was activated and impregnated by varying the concentration of NiO (1, 3, and 5% w/w). The characteristics of the catalyst were determined by the crystallinity (X-Ray Diffraction), surface area (Surface Area Analyzer), and functional group (Fourier Transform Infrared). The catalyst and crude biodiesel were put in an autoclave reactor and operated at a temperature of 375°C and 3 hours. The obtained product was tested with Gas Chromatography-Mass Spectroscopy. The results of the XRD analysis showed the presence of NiO at 2θ 37.23; 43.15; and 62.65°. Nickel oxide on the catalyst was detected at a wavenumber of 671.23 cm‑1. The highest surface area was obtained at a NiO/Zeolite 1% of 49.4 m2/g. 1% NiO/Zeolite catalysts gave the best results on catalytic cracking of crude biodiesel with a reaction conversion of 60.79% and selectivity of 9,73%; 29,64% and 9,18% for biogasoline, biokerosene, and green diesel, respectively.

Oxidation of carbon monoxide over supported nickel oxide catalyst: kinetic model development and identification

The kinetics of carbon monoxide oxidation over alumina supported nickel oxide was studied using a mechanistic approach to model development and identification. Langmuir-Hinshelwood and Eley-Rideal reaction schemes, together with an alternative scheme were investigated, using low temperature, differential rate measurements. Experimental results were found to be most consistent with the alternative scheme, supporting a reaction mechanism based on non-competitive adsorption of carbon monoxide and oxygen onto different catalyst sites without mutual displacement. The resulting kinetic model was observed to have reasonable agreement with the experimental findings and was found representative of the system.