Effect Of Ni Loading Research Articles

Effects of Ni loading and Ce doping on a CaO-based dual function material for integrated carbon capture and in situ methanation

A Ni/CeNiCa dual-function material featuring a Ce promoter and Ni pre-doping shows an impressive CO2 capture capacity and in situ CH4 production.

Investigation on Integrated CO2 Capture and Conversion Performance of Ni-CaO Dual-Function Materials Pellets: Effect of Ni Loading and Optimization of Operating Parameters

Investigation on Integrated CO₂ Capture and Conversion Performance of Ni-CaO Dual-Function Materials Pellets: Effect of Ni Loading and Optimization of Operating Parameters

Effect of Ni loading onto Pt (Pt‐Ni/C) electrocatalysts for PEM fuel cell: A study of ORR activity, stability, and temperature effect

AbstractPt is a noble metal when alloyed with transition metals like Ni onto the carbon support, minimizes the cost and increases the oxygen reduction reaction (ORR) activity and stability of Pt‐Ni/C electrocatalyst in a low‐temperature proton exchange membrane (LTPEM) fuel cell. A simple sonochemical‐based synthesis of Pt‐Ni/C bimetallic nanoparticles is carried out through varying amounts of Ni and Pt precursors. The various combinations of Pt and Ni metal (50:50, 75:25, and 83:17) nanoparticles were uniformly distributed on a carbon support. The shifting of 2θ values to higher levels in XRD patterns confirmed the alloy formation between Pt and Ni. The carbon (60 wt. %) supported Pt and Ni (40 wt. %) electrocatalyst ink is coated on a carbon paper which acts as a gas diffusion layer (GDL). The electrocatalytic performance of Pt‐Ni/C was evaluated in the PEM fuel cell using an electrochemical test station. The best performance was observed with the Pt: Ni (83:17) coated electrocatalyst, which delivered 0.162 W/cm2 power at 0.45 V. Also, the PEM fuel cell performance was enhanced by increasing the single cell's operating temperature.

Preparation of Ni/YSZ Catalysts for Application of Solid Oxide Electrolysis Cell Methanation

Co-electrolysis of CO2 and steam using solid oxide electrolysis cells (SOECs) is a major focus of the CO2 conversion. Furthermore, SOECs have the potential to drive high value-added products with reduced carbon footprint. For example, the syngas (mixture of CO and H2) can be produced by SOEC-driven co-electrolysis of CO2 and steam, and utilized in the Fischer-Tropsch (FT) process for the synthesis of artificial hydrocarbon. The artificial hydrocarbons would be environmentally friendly fuels when CO2 is obtained from carbon capture and storage (CCS) technology. The Ni-based cermet, such as Ni with yttria-stabilized zirconia (Ni/YSZ), is a typical material of SOEC device, and Ni has been found to be an active catalyst for CH4 production (methanation). Therefore, use of the Ni/YSZ has potential to directly convert CO2 and H2O to CH4. In the catalytic process, the activity, selectivity and durability of the Ni/YSZ catalyst are significantly influenced by the structural property of Ni and YSZ, which is varied by the Ni loading and calcination conditions in addition to the studied reaction conditions. The preparation of Ni/YZS catalyst with high performance in co-electrolysis and methanation is still challenging.Herein, the preparation of the Ni/YSZ catalysts with enhanced activity in SOEC methanation was studied. The Ni/YSZ catalysts were prepared by wet impregnation, one of the catalyst preparation methods, and characterized by several conventional methods. Effects of Ni loading and calcination conditions on the performance of Ni/YSZ catalysts were examined by CO2 methanation. A Ni/YZS catalyst gave a high CO2 conversion of 86% and a high methane selectivity at around 300 ºC under ambient pressure. With Ni/YSZ prepared using the optimized method, we are planning to prepare tubular cells and evaluate their activity in SOEC methanation.

Fabrication and catalytic evaluation of Ni/CaO–Al2O3 in glycerol steam reforming: Effect of Ni loading

The present study aims to assess the catalytic activity of the Ni/CaO–Al2O3 catalysts with different Ni loadings (2.5, 5, 10, 15, and 20 wt %) for H2 generation via the glycerol steam reforming (GSR). The support was prepared by the mechanochemical method, and then the various contents of nickel were impregnated on the support surface. The synthesized samples were characterized by BET, XRD, H2- TPR, CO2-TPD, TPO, FTIR, and SEM analyses. High stable catalytic activity was reported for the prepared catalysts. Among the investigated catalysts, 15%Ni/CaO–Al2O3 with the highest reducibility, proper BET area (96.6 m2 g−1), and suitable basicity possessed the highest catalytic performance with glycerol conversion of 99.4% at 700 °C. All the samples had high stability after 5 h, and the 15%Ni/CaO–Al2O3 showed 97.5% glycerol conversion at 550 °C without any decline in glycerol conversion durin 15 h time on stream. It was also found that glycerol conversion decreased with the increase in gas hourly space velocity and calcination temperature.

Active Ni and Fe species on catalysts Ni/Al2O3 and NiFe/Al2O3 for the oxidative dehydrogenation (ODH) of ethane to ethylene assisted by CO2

Ni/Al2O3 and NiFe/Al2O3 catalysts were synthesized by incipient wetness impregnation and tested for oxidative dehydrogenation (ODH) of ethane to ethylene. The effect of Ni loading and Fe as a promoter for bimetallic catalysts were characterized by X-ray diffraction (XRD), Raman spectroscopy, ultraviolet-visible diffuse reflectance spectroscopy (UV-vis DRS), scanning electron microscopy (SEM), and temperature-programmed reduction (H2-TPR). The catalyst with 10 wt% Ni and 6.6 wt% Fe (NiFe32) displayed the highest ODH activity. XRD results showed smaller crystalline NiO (˂ 7 nm) for bimetallic catalysts than the monometallic ones. Raman results depicted NiOx species in the monometallic catalysts. The bimetallic catalysts exhibited spinel-type structures as NiFe2O4 and FeAl2O4 related to more active species in ODH of ethane. DRS results revealed that the higher ODH activity for bimetallic catalysts is related to a predominance of Ni and Fe in tetrahedral symmetry (Td) than octahedral symmetry (Oh). These suggest that tetrahedral symmetry species were more effective than octahedral symmetry. TPR profiles showed that the iron addition increased the nickel species with strong interaction with the support. This rearrangement of Ni and Fe species in octahedral and tetrahedral sites of the NiO and alumina lattice could explain the shift reduction temperatures for Ni species and the formation of the spinel-type structure in the bimetallic catalysts. A relation between the metal-support interaction and the selectivity toward ethylene was found. A higher strong metal-support interaction favors a better catalytic activity.

Selective Production of Light Aromatics from Hydrocracking of Pyrolytic Lignin over Ni/HZSM-5

Pyrolytic lignin (PL), namely the water-insoluble fraction of bio-oil, is mainly composed of phenolic oligomers, and therefore, it has the potential to be converted into light hydrocarbons and phenols. This work studied the hydrocracking of PL for the generation of light aromatics (including monoaromatic hydrocarbons, double-ring aromatic hydrocarbons, and monophenols). By comparing different PL conversions, the reaction mechanism of PL hydrocracking over Ni/HZSM-5 was proposed, and particularly, the synergistic catalytic effects of Ni and acid sites on hydrodepolymerizatrion and hydrodeoxygenation were explained. Then, the effects of Ni loading on Ni/HZSM-5, reaction temperature, and reaction pressure were investigated and discussed based on the proposed reaction mechanism. It was found that a good balance of Ni and acid sites under the Ni loading of 10% could achieve the best synergistic effect for hydrodepolymerization and hydrodeoxygenation. A suitable reaction temperature of 500 °C achieved the efficient hydrodepolymerization and hydrodeoxygenation, while the removal of alkyl side groups attached to the benzene ring was not intense. Continuously increasing the reaction pressure to 4 MPa also facilitated the hydrodepolymerization of PL as well as the hydrodeoxygenation of the monophenols. Under the optimum reaction parameters, the yields of monoaromatic hydrocarbons, double-ring aromatic hydrocarbons, and monophenols reached 16.61%, 7.81%, and 9.36%, respectively. The spent catalyst was deactivated because of the carbonaceous deposits on it, and it could be well regenerated by burning these carbonaceous deposits.

High coke resistance Ni-SiO2@SiO2 core-shell catalyst for biogas dry reforming: Effects of Ni loading and calcination temperature

In this study, Ni-SiO2@SiO2 core-shell catalysts were prepared using the ammonia evaporated synthesis method, followed by encapsulation by a silica layer. The effect of nickel content and calcination temperature on the catalytic activity were separately studied in the biogas dry reforming reaction. The results revealed that the catalytic activity improved and carbon deposition increased when nickel content increased from 2.5 to 15 wt.%. Ni-SiO2@SiO2 with 10 wt.% Ni loading exhibited stable and high methane and CO2 conversions with negligible carbon formation during 12 h time on stream at 700 °C. Also, because of the high carbon resistance property of the prepared catalysts, the CH4 conversion over Ni-SiO2@SiO2 catalyst remained constant at 52% for 12 h at a low reaction temperature of 600 °C. Compared with Ni-SiO2@SiO2 core-shell catalyst, Ni/SiO2 supported catalyst fabricated by impregnation method exhibited lower activity and stability. High stability and carbon deposition resistance properties of the Ni-SiO2@SiO2 catalyst were ascribed to the strong Ni-SiO2 interaction and coverage of the Ni particles by SiO2, which make them resistant against migration and sintering. The results indicated that the catalytic activity gradually improved with the augment of calcination temperature from 600 to 800 °C. Ni-SiO2@SiO2 catalyst calcined at 800 °C with moderate nickel size and intermediate Ni-SiO2 interaction demonstrated the best catalytic activity.

Renewable hydrogen production via glycerol steam reforming over Ni/CeO2 catalysts obtained by solution combustion method: The effect of Ni loading

A series of nanocrystalline Ni/CeO2 catalysts with various Ni content was prepared by urea-nitrate combustion synthesis and evaluated in glycerol steam reforming for renewable H2 production. The as-prepared, reduced and spent catalysts were characterized by various analytical techniques such as XRD, N2-physisorption, SEM–EDX, TEM–HAADF and SAED, H2-TPR, XPS, Raman, and DTA–TGA. NiO is predominantly in the X-ray amorphous state (particle size 2–4 nm regardless of the Ni amount), which is retained for Ni0 particles after reduction by H2. Significant fraction of NiO(Ni0) is localized between CeO2 aggregates. An increase in the Ni content leads to inhibition of the agglomeration of CeO2 crystallites and increase in CeO2 defectiveness up to 6.8 wt% Ni; formation of CeO2(Ni2+) solid solution at 8.7 wt% Ni, which decomposes upon reduction. The sample containing 6.8 wt% Ni exhibits the best combination of Ni content and dispersion, CeO2 defectiveness, glycerol conversion, H2 yield, selectivity to H2 and CO2 and has low selectivity to hydrocarbons. TEM and DTA–TGA revealed the formation of amorphous, graphite-like, and fibrous coke depending on the Ni amount. This formation leads to accelerated deactivation due to partial agglomeration of Ni0 particles and encapsulation of amorphous nickel.

Methane decomposition over Ni supported on palm oil fuel ash (Ni-POFA) catalyst

The performance of Ni supported on palm oil fuel ash (Ni-POFA) catalyst was evaluated for methane decomposition reaction. The effects of Ni loading (5, 10, 15 and 20 wt.%) and gas hourly space velocity (GHSV) (5000, 7000, 15,000 and 25,000 mL/g h) were investigated at 550 °C for 6 h. The results show that increasing the Ni loading from 5 to 15 wt.% increased the initial H2 yield. However, the highest Ni loading (20 wt.% Ni) resulted in the lowest CH4 conversion and H2 yield, which has been associated to Ni particles agglomeration and formation of large filamentous carbon. The increase of GHSV from 5000 to 7000 mL/g h increased the initial CH4 conversion and initial H2 yield. Nonetheless, the catalytic performance of Ni-POFA degraded rapidly at higher GHSVs (15,000 and 25,000 mL/g h). This has been linked to a shorter contact time between CH4 gas and the catalyst at higher CH4 flow rates. The current study proposes the 15 wt.% Ni and 7000 mL/g h as the optimum Ni loading and GHSV for Ni-POFA catalyst, respectively. Under these conditions, methane decomposition performed admirably at 87.0% initial CH4 conversion and 27.0% initial H2 yield. Under the same conditions, the highest stable value of H2 production was achieved at ∼2.0% over the 6-h reaction time.

Solvent-free elaboration of Ni-doped MnOx catalysts with high performance for NH3-SCR in low and medium temperature zones

Cryptomelane-type Ni-doped MnOx catalysts (NMOs) prepared by solvent-free doping method showed very attractive performances in wide temperature zones and stability for selective catalytic reduction (SCR) at 100–300 ℃. The effect of Ni loading on NH3-SCR activity at medium temperature (200–300 ℃) was investigated. The NMOs-4 catalyst not only maintained excellent low temperature (100–200 ℃) NH3-SCR activity, the NO conversion was approached to 100 %, but also significantly improved the medium temperature activity while the NO conversion increased from 54.4% to 87.2% at 300 ℃ (T95 = 100–265 ℃) compared with undoped MOs catalyst (T95 = 100–225 ℃). Appropriate Ni loading could effectively tune the surface lattice oxygen activity and acidity of catalyst to ensure the NH3 activation ability at low temperature and inhibit the occurrence of NH3 direct oxidation at higher temperature. On other words, moderate NH3 activation capacity was the key to achieve a wide temperature region of MnOx-based catalysts.

Ni-based catalysts supported on MgAl2O4 with different properties for combined steam and CO2 reforming of methane

Three MgAl2O4 spinels were prepared by co-precipitation (cp), sol–gel (sg) and alcoholysis (al) methods, and used as supports for Ni catalysts for combined steam and CO2 reforming of methane (CSCRM). MgAl2O4(cp), MgAl2O4(sg) and MgAl2O4(al) showed different textural, morphological and chemical properties. By comparison of the properties of MgAl2O4 with those of 10Ni/MgAl2O4 (10 wt% Ni loading), it was found that the basicity of MgAl2O4 was a major factor influencing not only the basicity of catalyst but also the Ni particle size and dispersion. MgAl2O4(sg) possessed the highest amount of basic sites leading to 10Ni/MgAl2O4(sg) having the strongest basicity and the smallest Ni particle size. These properties bestowed 10Ni/MgAl2O4(sg) with superior anti-coking and anti-sintering properties as well as the highest activity and stability for CSCRM among all catalysts including 10Ni/MgO and 10Ni/γ-Al2O3. Further investigations on the effect of Ni loading (5–15 wt%) showed that 10Ni/MgAl2O4(sg) was the best catalyst for CSCRM, with stable conversions of CH4 (88.9%) and CO2 (68.6%) over 30 h on stream (CH4:H2O:CO2 = 2.5:2:1 (molar ratio)) at 800 °C, 0.1 MPa and a gas hourly space velocity of 132,000 NmL/(gcat·h).

Preparation of hydrogen-rich gas by catalytic pyrolysis of straw-plastic mixture with nickel-based honeycomb cinder

Nickel catalyst supported on honeycomb cinder (Ni/HC) was prepared by a homogeneous precipitation method. The catalyst was applied to produce hydrogen-rich combustible gas by catalytic pyrolysis of soybean straw and plastic (PE) mixture. The straw and plastic materials were analyzed by elemental analysis and industrial analysis. The support and catalyst were characterized by X-ray fluorescence (XRF), X-ray diffraction (XRD), scanning electron microscopy (SEM), and N2 adsorption-desorption isotherm (BET). The analysis showed that NiO was well loaded on the surface of honeycomb coal slag carrier. The effects of Ni loading, pyrolysis temperature, holding time, and calcination temperature on the experimental results were studied. The results showed that the preparation of the catalyst was feasible and that it had a good catalytic effect. When Ni loading was 15 wt.%, catalytic pyrolysis temperature was 700 °C, holding time was 20 min, and calcination temperature of catalyst was 400 °C, H2 concentration increased from 20.6 to 52.8 vol.%, and while H2 yield was 302 mL/g, CH4 concentration decreased from 51.1 to 22.6 vol.% and CO concentration increased from 10.8 to 17.8 vol.%. After the catalyst was regenerated 6 times, the H2 concentration still reached 40 vol.% and the combustible gas concentration was still above 80 vol.%. The catalyst still had good catalytic activity.

Glycerol etherification towards selective diglycerol over mixed oxides derived from hydrotalcites: effect of Ni loading

A series of tetrametallic hydrotalcite with different Ni loading, were synthesized by coprecipitation method. Then, these hydrotalcites were calcined in their respective metal oxides and were used as catalysts in the etherification reaction for the synthesis of polyglycerols. The effect of Ni loading on the structural and textural features was investigated by various techniques such as X-ray diffraction (XRD), thermogravimetric analysis TG–DSC–MS, temperature-programmed reduction (H2-TPR), temperature-programmed desorption (NH3-TPD) and 1-butene isomerization as a model reaction to probe acid–base character of catalysts. Mixed oxides derived from hydrotalcites are found to be active and suitable, via solvent free, in the glycerol etherification reaction. A gradual enhance of glycerol conversion is revealed when increasing the Ni/Mg molar ratio and the most active catalyst found is HTc-Ni75% with full selectivity to diglycerol.

Effect of Ni loading and impregnation method on the hydrodenitrogenation of coal tar over Ni-Mo/γ-Al2O3

ABSTRACT Ni-Mo/γ-Al2O3 catalysts with different Ni loadings were prepared. They were characterized by X-ray diffraction (XRD), N2 adsorption, IR spectra of adsorbed pyridine (Py-IR), temperature-programmed desorption of ammonia (NH3-TPD), temperature-programmed reduction of H2 (H2-TPR), and high resolution transmission electron microscopy (HRTEM). The hydrodenitrogenation (HDN) performance of catalysts for coal tar were evaluated. The best hydrodenitrogenation activity was observed on the catalysts with a Ni loading of 6.25 wt% and a Ni/(Ni+Mo) ratio of 0.4. Also, the methods of co-impregnation and sequence-impregnation were compared. The denitrification rate of co-impregnation catalyst NiMo-5-co (71.2%) was slightly lower than that of sequence-impregnation catalyst NiMo-5 (71.7%). Disparate product distribution was obtained on NiMo-5-co and NiMo-5. The dispersion of active components, the distribution of pore and acid on catalysts played an important role in HDN process of coal tar.

Steam reforming of acetic acid in the presence of Ni coated with SiO2 microsphere catalysts

Steam reforming of acetic acid was investigated in the presence of Ni@SiO2 microsphere catalysts. The effects of Ni loading, H2O/AcOH ratio, and temperature on hydrogen selectivity and acetic acid conversion were determined via statistical analysis. Results indicated the dependence of parameters on hydrogen selectivity.The stable activity observed for the reaction conducted at 2.5H2O/AcOH ratio and 750 °C implied future utilization potential of the catalyst for time on stream experiments despite the inevitable coke formation. Boudard reaction and methane decomposition, known as possible carbon sources, was ruled out due to the opposite trends between CO2 and CO selectivities and mitigation of methanation reactions. The ambiguous pattern of conversions observed for varying H2O/AcOH implied the presence of a different reaction path leading to consecutive ketonozation of acetic acid and aldol-condensation of acetone as the primary sources of carbon deposition.

The reaction kinetics of CO2 methanation on a bifunctional Ni/MgO catalyst

A bifunctional Ni/MgO catalyst was prepared to catalyze CO2 methanation and make use of CO2 as an abundant hydrogen storage facility. The effect of Ni loading and MgO quality on the rate of methanation was tested in a temperature range of 533–648K. The Ni loading was varied between 0 to 27wt.% on MgO. To investigate the impact of matrix elements, a MgO/CaO support was tested with 21wt.% nickel loading. Further, the role of MgO in the bifunctional catalyst was proven. The reaction kinetics was modeled with a Langmuir–Hinshelwood approach considering the bifunctional character of the catalyst. Nickel provides the adsorbent capacity for hydrogen and is highly selective for methane. MgO activates CO2 through chemisorption. Increasing Ni loading of the catalyst increased the rate of CO2 conversion. According to the results, the mechanism of CO2 methanation did not change with Ni loading. The Ni/MgO catalyst acted as a robust, active and highly selective catalyst for CO2 methanation. With CO2 conversion of 87%, the selectivity to methane was ≥99%. Besides excellent catalytic activity the catalysts suffice the necessity of simple catalyst preparation, usage and recyclability for industrial applicability of CO2 methanation.

A study on catalytic activity of modified Ni–Re/Al-SBA-15 catalyst for hydrodenitrogenation of o-toluidine

To elucidate the influence of Al content and effect of Ni loading on the structure and catalytic activity for hydrodenitrogenation reaction of o-toluidine, a series of mesoporous Al-SBA-15 supported Ni–Re sulphided catalysts were prepared. The textural and chemical properties of support and catalyst were analysed using XRD, N2-sorption studies, DRS UV–Vis, SEM, HRTEM, NH3-TPD, TPR and XPS. These characterizations indicate that the incorporation of Al content into the SBA-15 framework leads to the formation of moderate acid sites, which shows enhanced catalytic activity. The maximum catalytic activity in 1 wt%Ni-5wt%Re/Al-SBA-15(10) catalyst is due to fine dispersion of Re and Ni over the support, strong metal–support interaction, high degree of sulphidation and more sulphur atoms on the surface.

Effects of Ni loading on the physicochemical properties of NiOx/CeO2catalysts and catalytic activity for NO reduction by CO

The NO reduction by CO reaction was investigated using NiOx/CeO2catalysts with different Ni loadings. Surface NiOxcontrols the catalytic activity which was related to the molecular structure and reducibility of the catalysts.

Catalytic Conversion of Levulinic Acid to γ-Valerolactone over Hierarchical AlPO4-5 Supported Nickel Catalysts

Catalytic conversion of biomass based platform chemicals to value added chemicals has attracted much attention recently. In this work, Ni-based catalysts were developed for the conversion of levulinic acid to γ-valerolactone. By investigation of reduction behavior of NiO, it was found that a relatively low reduction temperature (300°C) can provide the reduction of NiO to Ni0. The high reduction temperature (500°C) generally applied in literature is not necessary. The effect of supports was also studied, and hierarchical AlPO4-5 (AlPO4-5-meso) supported Ni showed the best catalytic performance due to the proper pore size of AlPO4-5-meso, which contains both micropores and mesopores. The effect of Ni loading was also investigated, 10 wt % of Ni is enough for this reaction, which is lower than the reported amount of Ni loading. By using Ni/AlPO4-5-meso with 10 wt % Ni as catalyst, 84% γ-valerolactone yield and 100% levulinic acid conversion can be obtained after reaction for 10 h at 180°C.