Effect Of Ni Loading Research Articles

Effect of Ni loading on SBA-15 synthesized from palm oil fuel ash waste for hydrogen production via CH4 dry reforming

The successful synthesis of SBA-15 using silica source extracted from palm oil fuel ash (POFA) was proven with the presence of mesostructure characteristics as evidenced by low angle XRD, N2 adsorption-desorption isotherms and TEM. Different amounts of Ni were loaded on the synthesized SBA-15(POFA) using the impregnation method at 80 °C. The influence of Ni loading over the Ni/SBA-15(POFA) physiochemical properties and CO2 reforming of CH4 (CRM) were investigated in a stainless steel fixed-bed reactor at 800 °C and atmospheric pressure with 1:1 CO2:CH4 volumetric feed composition. An increment in Ni loading on SBA-15(POFA) from 1 to 5 wt% decreased the BET surface area and crystallinity of catalyst as proven by N2 adsorption–desorption and XRD analysis. The catalytic performance of CRM followed the sequence of 3 wt% > 5 wt% > 2 wt% > 1 wt% -Ni/SBA-15(POFA). This result was owing to the even distribution of Ni and good Ni–O–Si interaction of 3 wt% Ni/SBA-15(POFA) as proved by TEM, FTIR and XPS. Lowest H2/CO ratio and catalyst activity and stability of 1 wt% Ni/SBA-15(POFA) were due to the weaker Ni–O–Si interaction and small amount of basic sites that favor the reverse water gas shift (RWGS) reaction and carbon formation. The recent finding indicates that a quantity as small as 3 wt% Ni loaded onto SBA-15(POFA) could elicit outstanding catalytic performance in CRM, which was comparable with 10 wt% Ni loading catalysts reported in literature.

110th Anniversary: Dry Reforming of Methane over Ni- and Sr-Substituted Lanthanum Zirconate Pyrochlore Catalysts: Effect of Ni Loading

Pyrochlores are thermally stable materials that can be doped with a metal to produce active catalyst for dry reforming of methane (DRM). La1.95Sr0.05Zr1.904Ni0.096O7–d (LSNZ1) and La1.95Sr0.05Zr1.4...

Hydrogen-rich syngas production by catalytic cracking of tar in wastewater under supercritical condition

This paper presents the results from experimental study of syngas production by catalytic cracking of tar in wastewater under supercritical condition. Ni/Al2O3 catalysts were prepared via the ultrasonic assisted incipient wetness impregnation on activated alumina, and calcined at 600 °C for 4 h. All catalysts showed mesoporous structure with specific surface area in a range of 146.6–215.3 m2/g. The effect of Ni loading (5–30 wt%), reaction temperature (400–500 °C), and tar concentration (0.5–7 wt%) were systematically investigated. The overall reaction efficiency and the gas yields, especially for H2, were significantly enhanced with an addition of Ni/Al2O3 catalysts. With 20%Ni/Al2O3, the H2 yield increased by 146% compared to the non-catalytic experiment. It is noteworthy that the reaction at 450 °C with the addition of 20%Ni/Al2O3 had a comparable efficiency to the reaction without catalyst at 500 °C. The maximum H2 yield of 46.8 mol/kgtar was achieved with 20%Ni/Al2O3 at 500 °C and 0.5 wt% tar concentration. The catalytic performance of the catalysts gradually decreased as the reuse cycle increased, and could be recovered to 88% of the fresh catalyst after regeneration. 20%Ni/Al2O3 has a potential to improve H2 production, as well as a good reusability. Thus, it is considered a promising catalyst for energy conversion of tar in wastewater.

Evaluation of stability and catalytic activity of Ni catalysts for hydrogen production by biomass gasification in supercritical water

Supercritical water gasification is a promising technology for wet biomass utilization. In this paper, Ni and other metal catalysts were synthesized by wet impregnation. The stability and catalytic activities of Ni catalysts were evaluated. Firstly, catalytic activities of Ni, Fe, Cu catalysts supported on MgO were tested using wheat straw as raw material in a batch reactor at 723 K and water density of 0.07 cm3/g. Experimental results showed that the order of metal catalyst activity for hydrogen generation was Ni/MgO > Fe/MgO > Cu/MgO. Secondly, the influence of different supports on Ni catalysts performance was investigated. The results showed that the order of the Ni catalysts’ activity with different supports was Ni/MgO > Ni/ZnO > Ni/Al2O3 > Ni/ZrO2. Finally, the effects of Ni loading and the amount of Ni catalyst addition on hydrogen production, and the stability of Ni/MgO catalyst were studied. It was found that serious deactivation of Ni catalyst in the process of supercritical water gasification took place. Even if carbon deposited on the catalyst surface was removed by high temperature calcination and the catalyst was reduced with hydrogen, the activity of used catalyst was only partially restored.

Hydrodeoxygenation of methyl laurate over the sulfur-free Ni/γ-Al2O3 catalysts

A series of sulfur-free Ni/γ-Al2O3 catalysts with different metal Ni loading amount were prepared by impregnation method. The prepared catalysts and corresponding precursors were investigated through XRD, BET, H2-TPD, and H2-TPR analysis methods. The effect of Ni loading on catalytic performance of Ni/γ-Al2O3 catalysts was evaluated by methyl laurate catalytic hydrodeoxygenation (HDO). Results indicate that the catalytic HDO performance of the prepared Ni/γ-Al2O3 catalysts was directly related to hydrogen storage properties, hydrogen desorption properties, dispersion of the active component Ni, and so on. The 10 wt.% Ni/γ-Al2O3 catalyst exhibits the best HDO performance, and the methyl laurate conversion can reach 91.1% when the reaction temperature is 400 °C and pressure is 2 MPa. The HDO products are alkanes, such as C<10, C10, C11, C12 alkane, C12 alcohol, and C12 acid, especially. The main product C11 alkane with one carbon less is formed by decarbonylation/decarboxylation, and selectivity can reach 68.6%. The effects of reaction conditions on HDO reaction of oils were studied, for example, reaction pressure and H2/Oil ratio. The catalyst retains comparable activity upon regeneration through calcinations and H2 reduction.

Effect of Ni-loading on Sm-doped CeO&lt;sub&gt;2&lt;/sub&gt; anode for ammonia-fueled solid oxide fuel cell

Effect of Ni-loading on Sm-doped CeO&lt;sub&gt;2&lt;/sub&gt; anode for ammonia-fueled solid oxide fuel cell

올레산의 탈산소 반응에서 Ni-Ce0.6Zr0.4O2 촉매의 Ni 담지량에 따른 영향

올레산의 탈산소 반응에서 Ni-Ce0.6Zr0.4O2 촉매의 Ni 담지량에 따른 영향

Selective hydrogenation of benzoic acid to cyclohexane carboxylic acid over microwave-activated Ni/carbon catalysts

High yields of cyclohexane carboxylic acids were obtained by direct hydrogenation of aromatic carboxylic acids over different Ni/carbon catalysts having distinctive surface properties. The catalysts were characterized by SEM, TEM, H2-TPR and N2 adsorption isotherms for the determination of BET surface area and porosity. The hydrogenation reaction was carried out in batch pressure reactor in gas-liquid phase at 200°C. High selectivity (100%) of cyclohexane carboxylic acids at 86.2mol% conversion of benzoic acid was achieved over microwave-activated biochar supported non-precious metal Ni catalyst. The 10%Ni/CSC-b catalyst has been investigated for hydrogenation of benzoic acid to cyclohexane carboxylic acids and shown little deactivation in stability test. The effects of Ni loading, high dispersion of Ni species, appropriate power of microwave heating and strong interaction of Ni species with carbon are of benefit to the reaction.

Synthesis of Multi-walled Carbon Nanotubes on Ni/SiO2

Multi-walled carbon nanotubes were synthesized by Chemical Vapor Deposition on supported Ni/SiO2 using carbon monoxide as carbon source. The effect of Ni loading and feed gas on carbon nanotubes was studied. The yield of carbon was very low when Ni loading was 5% and the yield increased with the increase of Ni loading from 5% to 35%. Then the yield decreased after Ni loading is over 35%. The carbon nanotubes were characterized by TEM, HRTEM and XRD. It was found that the morphology of carbon nanotubes became poor with the increase of Ni loading. The optimum reaction temperature is 600℃ from both aspects of carbon yield and morphology. Without hydrogen in the feed gas, the diameter of carbon nanotubes was in a narrow range of 10~20nm. After hydrogen was introduced to the system, the amount of carbon was enhanced but the morphology became worse.

Facile synthesis of MgO and Ni-MgO nanostructures with enhanced adsorption of methyl blue dye

Nanostructured Magnesium oxide (MgO) was prepared by a simple method using a non-ionic block copolymer as surfactant. Ni was introduced to MgO to improve surface properties. The effect of Ni loading on the MgO crystalline structure, surface morphology and magnetic properties was observed by powder X-ray diffraction, field-emission scanning electron microscopy and a vibrating sample magnetometer, respectively. Textural properties of produced samples were investigated by nitrogen adsorption–desorption isotherms and the Brunauer–Emmett–Teller method. The as-prepared samples were employed as an adsorbent for the removal of Methyl blue (MeB) dye. The adsorption isotherms were studied using the Langmuir model. The results show a high adsorptive behavior for relatively high concentrated MeB with a maximum adsorption capacity of 367mgg–1 indicating the enhanced adsorption performance of our produced structures. A mechanism for adsorption of MeB molecules on the prepared MgO is proposed.

Syngas production via steam reforming of bioethanol over Ni–BEA catalysts: A BTL strategy

In this work we focused on syngas production from bioethanol, achieving proper H2/CO = 2 ratio to feed the FT reaction. The catalysts were constituted by Ni supported over BEA zeolites. The Si/Al ratio was varied to assess the effect of acidity on catalyst activity, selectivity and stability. As well, the effect of Ni loading (0.6–4 wt%) was investigated.Ni confinement into the zeolite pores proved a successful strategy to contrast deactivation by coking and to ensure stable operation with time-on-stream. Intermediate Ni loading (1.5–4 wt%) allowed to limit byproducts formation and to achieve the desired H2/CO ratio (ca. 2 mol/mol) for the present application. By contrast, increasing Ni loading increased the activity for both the reforming and the water gas shift reactions, thus improving H2 productivity but unbalancing the reaction mixture for application in the FT process. The conversion of CO through the WGS reaction showed strongly correlated to Ni loading, as well as the reforming of methane, a byproduct of bioethanol decomposition. The equilibrium conversion was achieved at the highest Ni loading.

Highly dispersed Ni/montmorillonite catalyst for glycerol steam reforming: Effect of Ni loading and calcination temperature

Montmorillonite (MMT) supported nickel nanoparticles (Ni/MMT) were prepared by an ultrasound assisted cation exchange impregnation method with rising pH technique. The Ni/MMT catalysts were characterized by different techniques including thermogravimetric analysis (TGA), N2 adsorption-desorption, X-ray powder diffraction (XRD), scanning electron microscope (SEM), energy-dispersive X-ray spectroscopy (EDS), transmission electron microscope (TEM), temperature programmed reduction (TPR), and temperature programmed oxidation (TPO). The characterization results showed the particle size, metal-support interaction, nickel dispersion interrelated with cation exchange capability and confinement effect of montmorillonite lamellar structure. The activity and stability tests were conducted in a fixed bed reaction and the reaction parameters of 600°C and S/C=3 were optimized. The effect of Ni loadings and calcination temperature were investigated. The results show that the Ni dispersion, particle sizes of Ni and metal-support interaction (MSI) are closely dependent on the Ni loading and calcination temperature. The MMT support favors dehydrogenation reaction pathway which is effective to suppress the coke deposition and the lamellar structure could provide strong confinement effect which is effective to inhibit Ni sintering. The phyllosilicate content in MMT could promote WGS reaction which is conducive to produce hydrogen rich gas with low CO concentration.

Preparation of highly active and stable nanostructured Ni/CeO2 catalysts for syngas production by partial oxidation of methane

Nickel catalysts supported on nanocrystalline CeO2 were prepared with impregnation method and employed in methane partial oxidation. The prepared catalysts were characterized by BET, XRD, TPR, SEM and TPO techniques. The effect of Ni loading on the catalytic performance of the catalysts was investigated and the results showed that 10% Ni/CeO2 catalyst possessed the highest catalytic activity. This catalyst showed high stability exposed to the reaction conditions for 48 h without any decrease in activity and selectivity. The results also showed that increasing in O2/CH4 molar ratio from 0.25 to 0.75 decreased the amount of deposited carbon and increased methane conversion. Also, with increasing the reaction temperature, amount of deposited carbon slightly increased. The results indicated that methane conversion decreased with increasing the catalyst calcination temperature due to sintering and decreasing in surface area.

Co-production of hydrogen and carbon nanotubes on nickel foam via methane catalytic decomposition

The co-production of COx-free hydrogen and carbon nanotubes (CNTs) was achieved on 3-dimensional (3D) macroporous nickel foam (NF) via methane catalytic decomposition (MCD) over nano-Ni catalysts using chemical vapor deposition (CVD) technique. By a simple coating of a NiO–Al2O3 binary mixture sol followed by a drying–calcination–reduction treatment, NF supported composite catalysts (denoted as NiyAlOx/NF) with Al2O3 transition-layer incorporated with well-dispersed nano-Ni catalysts were successfully prepared. The effects of Ni loading, calcination temperature and reaction temperature on the performance for simultaneous production of COx-free hydrogen and CNTs were investigated in detail. Catalysts before and after MCD were characterized by XRD, TPR, SEM, TEM, TG and Raman spectroscopy technology. Results show that increasing Ni loading, lowering calcination temperature and optimizing MCD reaction temperature resulted in high production efficiency of COx-free H2 and carbon, but broader diameter distribution of CNTs. Through detailed parameter optimization, the catalyst with a Ni/Al molar ratio of 0.1, calcination temperature of 550°C and MCD temperature of 650°C was favorable to simultaneously produce COx-free hydrogen with a growth rate as high as 10.3% and CNTs with uniform size on NF.

Effect of Ni Loading on Lanthanide (La and Ce) Promoted γ-Al2O3 Catalysts Applied to Ethanol Steam Reforming

Hydrogen production from ethanol steam reforming over xNi/15 %La2O3–10 %CeO2–γ-Al2O3 (x = 5, 10 and 15 wt %) catalysts was investigated with an ethanol:water = 1:3 feed composition. The results of catalysts characterization suggest that Ni metal particles have a strong metal support interaction with the promoters on the surface. Ethanol was completely converted to hydrogen and C1 products (CO, CO2, CH4) even at 723 K due to the remarkable C–C bond cleavage capacity and resistance to coke formation conferred by the promoters at low metal loadings. The increase of Ni particle size decreases the stability and selectivity; catalyst deactivation during 24 h on stream was attributed to coke deposition.

Dry reforming of methane over Ni/Ce0.62Zr0.38O2 catalysts: Effect of Ni loading on the catalytic activity and on H2/CO production

The activity of ceria–zirconia-supported nickel catalysts (Ni/CZ) with various loadings of nickel (2, 4 and 10 wt. %) was studied in the case of low-temperature dry reforming of methane (DRM). XRD, SBET, SEM, TPD-CO2 and thermogravimetry were used to determine the physicochemical properties of the catalysts and of the carbon deposits formed on the surface. It was found that the agglomerates of the Ni-active phase are formed on the surface of the support for high loadings of nickel. The best conversions of CO2 and CH4 and an optimum ratio H2/CO = 1 were obtained for the catalysts with the highest Ni content. It was also found that loading has an influence on the amount of carbon deposits formed in the DRM process.

Ni/SBA-15 Catalysts for combined steam methane reforming and water gas shift—Prepared for use in catalytic membrane reactors

This study focuses on the preparation, characterization and catalytic performance evaluation of Ni/SBA-15 catalysts for the combined steam methane reforming (SMR) and water gas shift (WGS) reaction. Specific efforts have been directed towards the impact of the SBA-15 preparation methods on further incorporating the resultant catalysts into the micro-structured ceramic hollow fibres for the development of more advanced membrane reactors. The effect of Ni loading (5–25wt.%) on the catalytic performance was investigated using the SBA-15 prepared via a sol–gel method. Furthermore, the effect of SBA-15 preparation methods (sol–gel and hydrothermal methods) on the catalyst properties and performance were also systematically investigated in a packed-bed reactor, using a fixed Ni loading of 25wt.%. For the purpose of comparison, a commercially available SBA-15 powder was also employed. Apart from the different distribution and particle size of Ni, the interaction between Ni and SBA-15 is considered as the major reason for the difference in catalytic performance.

ZnO–Carbon‐Nanotube Composite Supported Nickel Catalysts for Selective Conversion of Cellulose into Vicinal Diols

AbstractA ZnO‐nanolayer‐coated carbon nanotube (CNT) composite (ZnO–CNT) was employed as a support to immobilise Ni catalysts. Well‐mixed oxides, formed as a result of enhanced interfaces between the two oxides on CNTs, resulted in the formation of Ni–Zn alloys in reduced catalysts. The Ni/ZnO–CNT catalyst exhibited much higher yields of vicinal diols, for example, ethylene glycol and 1,2‐propylene glycol, from the conversion of cellulose than the reference Ni/CNT catalyst. A plausible reaction network on the Ni/ZnO–CNT catalyst has been proposed. Moreover, the effects of Ni loading and catalyst reduction temperature on the catalytic performance were probed, and the relationship between the catalyst structure and the yields of vicinal diols was correlated. The Ni‐rich alloy, relative to the Zn‐rich alloy, was suggested as the dominating active phase for the selective conversion of cellulose into vicinal diols. This might shed new light on the design and optimisation of Ni‐based catalysts for the catalytic conversion of cellulose with the Ni–Zn interaction.

CO2 methanation over Ni-promoted mesostructured silica nanoparticles: Influence of Ni loading and water vapor on activity and response surface methodology studies

• CO 2 methanation is dependence to the Ni loading (1–10 wt.%) on MSN. • The order of reaction activity was 10Ni/MSN ≈ 5Ni/MSN > 3Ni/MSN > 1Ni/MSN. • 0.5 vol% water vapor in the feed gave a negative effect on the CO 2 methanation. • Water vapor suppressed carbonyl species on the surface of Ni/MSN. • 85% conversion of CO 2 was achieved over 5Ni/MSN under the optimum condition by RSM. The effects of Ni loading and water vapor on the properties of Ni/mesoporous silica nanoparticles (MSN) and CO 2 methanation were studied. X-ray diffraction, N 2 adsorption–desorption, and pyrrole-adsorbed infrared (IR) spectroscopy results indicated that the increasing Ni loading (1–10 wt.%) decreased the crystallinity, surface area, and basic sites of the catalysts. The activity of CO 2 methanation followed the order of 10Ni/MSN ≈ 5Ni/MSN > 3Ni/MSN > 1Ni/MSN. These results showed that the balance between Ni and the basic-site concentration is vital for the high activity of CO 2 methanation. All Ni/MSN catalysts exhibited a high stability at 623 K for more than 100 h. The presence of water vapor in the feed stream induced a negative effect on the activity of CO 2 methanation. The water vapor decreased the carbonyl species concentration on the surface of Ni/MSN, as evidenced by CO + H 2 O-adsorbed IR spectroscopy. The response surface methodology experiments were designed with face-centered central composite design (FCCCD) by applying 2 4 factorial points, 8 axial points, and 2 replicates, with one response variable (CO 2 conversion). The Pareto chart indicated that the reaction temperature had the largest effect for all responses. The optimum CO 2 conversion was predicted from the response surface analysis as 85% at an operating treatment time of 6 h, reaction temperature of 614 K, gas hourly space velocity (GHSV) of 69105 mL g cat −1 h −1 , and H 2 /CO 2 ratio of 3.68.

Dry reforming over CeO2-promoted Ni/MgO nano-catalyst: Effect of Ni loading and CH4/CO2 molar ratio

Ceria promoted nickel catalysts supported on nanocrystalline MgO were prepared and employed in methane reforming with carbon dioxide. The prepared catalysts were characterized by XRD, BET, SEM, TPO and TPR techniques. The effect of nickel loading on the catalytic performance of catalysts was investigated and the results showed that 10%Ni–7%CeO2/MgO catalyst possessed the highest catalytic activity. The results also showed that increasing in CO2/CH4 molar ratio decreased the amount of deposited carbon and increased the methane conversion.