Papers by Keyword: Nickel Catalyst

Abstract: The aim of this research was to study the recycling process and the feasibility to smelt the spent nickel catalyst for the production of nickel alloy or ferronickel. The smelting process was carried out in a laboratory induction furnace. The effects of SiO₂/CaO for slag forming on metal recovery and smelting time were investigated. Petroleum coke was used as reductant. Mill scale was used as an iron resource for ferro-alloy production, while CaO was used as slag forming agent. The raw materials were mixed together and put into a graphite crucible, which was then placed in the induction furnace. After the melt was completed, the melt was poured into a mold to solidify. The chemical composition of the product was analyzed by XRF and XRD. It was found that the smelting time was decreased with increasing SiO₂/CaO from 1.0 to 2.3. For nickel alloy production, increasing of SiO₂/CaO increased the weight of metal product. For the ferronickel production, however, the weight of metal product was found not to vary with different ratio of SiO₂/CaO.

Abstract: The present study focuses on the derivation of carbonaceous material from rich premixed propane/air mixture using a laminar flame burner. The presence of Nickel catalyst (Ni) and the effect of equivalence ratio on the synthesis of carbon nanotubes (CNTs) were investigated. Samples were collected from the flame synthesized wire mesh and analyzed using a Field emission scanning electron microscope (FESEM). FESEM imaging shows that the CNTs obtained were of the multi-walled type. The presence of nickel catalyst results in the production of CNTs and the rich equivalent ratio of φ = 2.2 produces the highest yield of CNT in terms of weight and coverage area on the wire mesh.

Abstract: In this paper, the catalytic co-gasification of rubber seed shell and high density polyethylene mixtures (0.2:0.8 weight ratio of HDPE:RSS) are investigated using a non-isothermal thermogravimetric analysis (TGA) system in a range of heating rates of 10, 20, 30 and 50 K/min within the temperature range of 323-1173 K. The argon gas is supplied at a flowrate of 100 ml/min and the steam is generated from superheater at 383 K. The steam is injected at flowrate of 300 μL/hour into the TGA system. A commercial nickel powder is used as the catalyst for the gasification process. The thermal decomposition behavior and synergistic effect of the HDPE/RSS mixture are investigated. The activation energy, E_A and pre-exponential factor, A are determined based on one step integral method.

Abstract: Lignin was obtained from black liquor of papermaking by the acid to separation, and carbonized after loading various amounts of nickel and calcium or nickel alone. The influences of the temperature, amount of nickel and amount of calcium on the crystallized size (Lc) and the electromagnetic shielding (EMS) capacities in the range of 50~800 MHz for the chars from lignin were investigated. The results showed that Lc and EMS capacities in the entire of frequency of the chars with 6wt% calcium increased with increasing amount of the nickel loaded and also increased with increasing carbonization temperature from 700 to 900°C. Some amounts of calcium significantly enhanced the formation of crystallized carbon. Lc and EMS capacities of the chars with loaded 8wt% nickel increased with increasing amount of calcium and then decreased. It was founded that chars of lignin with co-loading of 8wt% nickel and 6wt% calcium were suitable as EMS materials with exceeding a practical standard of EMS capacity (30dB) in the range of 50~800 MHz.

Abstract: Nickel/carbon nanotubes (Ni/CNTs), Nickel/alumina (Ni/Al₂O₃), calcium-promoted Ni/CNTs and calcium-promoted Ni/Al₂O₃ were synthesized by impregnation method. Methanation of carbon dioxide was used as a probe to evaluate their catalytic performance. The features of these Ni-based catalysts were investigated via XRD, H₂-TPR, H₂-TPD and the N₂ adsorptiondesorption isotherms. H₂-TPR showed that nickel species on Ni/CNTs was reduced more easily with respect to that on Ni/Al₂O₃, and addition of Ca can increase the content of easily reducible Ni species for Ni/CNTs. XRD and H₂-TPD indicated that addition of Ca promoted dispersion for CNTs-supported catalyst. These finding ultimately enhanced catalytic activity and stability for Ni/CNTs catalyst modified with Ca.

Abstract: Aquathermolysis reaction of heavy oils occurring in high temperature water environment significantly degrades the heavy components of heavy oils, improves oil quality and reduces its viscosity. Aerosol, oil-soluble, and water-soluble nickel catalysts obviously and effectively catalyze the aquathermolysis reaction of heavy oils in a high temperature and reduces its viscosity, producing a gas increase of 49%, 41% and 21% respectively compared with the result with the absence of any catalyst. An aerosol, oil-soluble and water-soluble nickel catalyst compound (best quality ratio 1:1:2) increases the oil recovery of heavy oils by 8.5% and decreases the viscosity of sample oil and average relative molecular mass of porous media by 89.6% and 23% respectively, with its resin and asphaltene content significantly reduced. The pilot field tests show that, the test cycle production of heavy oils of each well proves an increase of 81.2 ~ 226.1t (not considering the cycle decline rate) over the previous one, which means that the field tests coincide with the laboratory experiments.

Abstract: Ni coatings were successfully electrodeposited on Ti substrates using galvanostatic technique. The scanning electron micrography showed a smooth coating with a few round particles formed at current density of-1 mA/cm², whereas the Ti surface was fully covered with round particles consisting of like-worm fibrils when applying higher current densities of-5 and-10 mA/cm². The stability and electrocatalytic activity tests were conducted by cyclic voltammetry and potentiostatic techniques. The results indicate that Ni/Ti catalysts prepared at current densities of-5 and-10 mA/cm² possess high active surface area and exhibit higher electrocatalytic activity performance towards methanol oxidation as compared to Ni/Ti prepared at-1 mA/cm². It was concluded that the deposition current density has significantly influenced the formation of Ni coatings on Ti substrate which consequently affecting the performance of electro-oxidation of methanol. The Ni/Ti catalysts also have good stability for the oxidation process in alkaline solution.

Abstract: The steam reforming of toluene as a model compound of biomass gasification tar was carried out over Mg and La oxide-promoted Ni-metal oxide/Al2O3 catalysts. Catalysts were prepared by two different methods, co- and sequential impregnation. The findings indicate that conversion of gas products was improved with the use of prepared catalysts especially on syn-gas (H2 and CO) species and the highest conversions were obtained at the reaction temperature of 800°C. LHV’s of product gas when using catalysts at 800°C were over 4 MJ/m3 and ratios of H2 to CO were between 2.49-2.77. For long term test, Carbon and hydrogen conversion to CO and H2 of the catalysts with respect to time on stream in the steam toluene reforming for 480 min were studied. La2O3+MgO+Ni/Al2O3 catalyst revealed the highest and stable conversion rate of closely 50% and 70% for CO and H2, respectively. Whisker carbon species and encapsulating carbon were found on used catalysts after reaction. The La2O3+MgO+Ni/Al2O3 catalyst showed lesser amount of whisker carbon and encapsulating carbon.

Abstract: Methane reforming is the most feasible techniques to produce hydrogen for commercial usage. Hence, dry reforming is the environment friendly method that uses green house gases such as CO₂ and methane to produce fuel gas. Catalysts play a vital role in methane conversion by enhancing the reforming process. In this study Ni/γ-Al₂O₃ was selected as based catalyst and CeO₂ and Fe₂O₃ dopants were added to investigate their effect on catalytic activity in dry reforming. The catalysts synthesized through wet impregnation method and characterized by using XRD, TEM and SEM-EDX. The catalytic tests were carried out using temperature programmed reaction (TPRn) and the products were detected by using an online mass spectrometer. The results revealed that these dopants significantly affect the catalytic activity and selectivity of the catalyst during reaction. Hence, Fe₂O₃ doped catalyst shows higher hydrogen production with stable catalytic activity.

Abstract: Carbon nanofibers with various morphologies were synthesized by the catalytic pyrolysis of acetylene using nickel catalyst nanoparticles at different reaction temperatures. Experimental results demonstrate that temperature is a critical parameter for controlling the size and morphology of carbon fibers. Twin coiled fibers and linearly bifurcating fibers emanating from nickel particles were formed at 400 °C; whereas, only linear carbon nanofibers were obtained at reaction temperatures of 450 °C, 500 °C, and 550 °C. At low temperatures, nickel nanoparticles remain in the middle of two fibers, while nickel particles are positioned at one end of the linear fibers at high temperatures.