Papers by Keyword: Nickel Oxide

Abstract: The synthesis, characterization, and application of a NiO-PO₄/SiO₂ catalyst for ethanol dehydration to diethyl ether were successfully conducted. The sol-gel method utilized TEOS as the silica source, NaHCO₃ as a template, and different phosphoric acid concentrations (1, 2, and 3 M). Calcination occurred at temperatures of 400, 500, and 600 °C. The catalyst with the highest acidity underwent impregnation with 1, 2, and 3% (w/w) nickel precursor proceeded by calcination with N₂ gas. Characterization techniques included FTIR, XRD, SEM-EDX, and AAS. The application of SP 2-NiO 3% catalyst as the catalyst with the highest acidity demonstrated significant activity and selectivity in diethyl ether production at 175, 200, and 225 °C temperatures, yielding 88% conversion and 5.07% diethyl ether selectivity at its optimum temperature of 225 °C.

Abstract: Oxidative desulfurization of dibenzothiophene (ODS-DBT) using catalyst of NiO impregnated on magnetic silica sand from Parangtritis beach (Ps) had been evaluated. The NiO-Ps catalyst was prepared using wet impregnation method with Ps to Ni (NO₃)₂·6H₂O weight ratio of 1:1. The catalyst was calcined at a temperature of 400 °C for 5 h under flow of 20 mL min^-1 of N₂ gas_. The ODS-DBT process was carried out using NiO-Ps catalyst on solution of n-hexane with a sulfur content of 500 ppm under variations of temperature, time, and H₂O₂ volume. The results of XRD and FTIR indicated the main minerals of Ps were quartz, alumina, and magnetite. The Ps and NiO-Ps had crystallinities of 59.97 and 70.32% with crystal sizes of 16.32 and 10.95 nm. The SEM-EDX and TEM analysis showed the surface of Ps was flat and NiO-Ps was rough. The BET-nitrogen absorption-desorption indicated the Ps and NiO-Ps were mesoporous materials with average pore diameters of 11.98 and 24.01 nm, total pore volumes of 0.008 and 0.057 cm³ g^-1, and specific surface areas of 2.611 and 9.502 m² g^-1. The Ps and NiO-Ps have acidity values of 1.14 and 1.74 mmol g^-1. The optimum desulfurization using NiO-Ps catalyst in the ODS-DBT was 79.40% obtained at a temperature, time, and H₂O₂ volume of 60 °C, 30 min, and 0.42 mL.

Abstract: Synthesis of 1,1–dipropoxypropane from a single reagent of n-propanol using Cr/Activated Carbon (Cr/AC) as a catalyst has been done. Activated carbon (AC) was prepared by activating coconut shell carbon at 650 °C in the atmosphere of N₂ at a flow rate of 20 mL/min for 4 h, and then it was washed using acetone in a Soxhlet for 15 rounds, washed three times by 1.0 M HCl, and finally, it was sieved at 60–80 mesh. Metal content was analyzed using atomic absorption spectroscopy (AAS) and represented by Na, Ca, and Fe. The AC was impregnated with Cr (VI) solution and reduced with H₂ at 650 °C. The acidity of the Cr catalyst was determined by the adsorption of ammonia. Optimation of n-propanol conversion to 1,1-dipropoxypropane using Cr/AC catalyst in the atmosphere of N₂ was conducted in an oven using variations of temperature of 450, 500, and 550 °C, amount of catalyst of 5, 10, and 15 g, and flow rate of alcohol of 0.10, 0.50, and 0.90 mL/min. The conversions of 1,1-dipropoxypropane were analyzed by GC-MS and ¹H-NMR. The results showed that the AC's metal content significantly decreased after washing with acetone and 1.0 M HCl. The AC and Cr/AC had 2.49 and 8.27 mmol/g acidity, respectively. The highest product of 1,1-dipropoxypropane of 65.0% was reached at 450 °C using a 5 g catalyst at a flow rate of the alcohol 0.10 mL/min.

Abstract: This study used Hibiscus sabdariffa flowers to prepare and characterise nickel oxide nanoparticles that are non-toxic and environmentally advantageous (green synthesis). After two hours of heat treatment at 600 °C, XRD was employed to validate the cubic crystal structure of NiO-NPs. The crystal plane (200) corresponded to the optimal peak on the XRD, With an average crystalline size, as per Williamson-Hall's formula, is 46.26 nm, while as per Scherrer's formula, it is 24.40 nm. At 524, 420, and 468 cm^-1, the FT-IR spectrum revealed a Ni-O vibration band. Throughout the surface microscopic analysis, Field-Emission Scanning Electron Microscopy (FE-SEM) revealed smooth, cylindrical rod-like crystals. As per the UV-Vis spectral curve, NiO-NPs had a direct bandgap (Eg) of 2.91 eV. NiO-NPs nanoparticles were shown to be more effective against gram-negative bacteria in terms of biological activities. P. aeruginosa was significantly more severely harmed than S. aureus.

Abstract: Nickel Oxide nanofibers were successfully prepared by electrospinning with a precursor mixture of Ni acetate/polyvinylpyrrolidone (PVP), followed by calcination treatment of the electrospun composite nanofibers. The parameter of solution and effect of applied voltage to the morphology of nanofibers were studied. Both Ni acetate/PVP and NiO NFs, nanofibers were characterized by FESEM and XRD. The results found that the nanofibers form with smooth surface without beads and the calcination temperature was at 500°C to produce NiO nanofibers.

Abstract: Zinc, nickel and silver oxide were prepared by the method of pulsed ablation laser in liquid, with different preparation conditions, where the number of pulses was changed (25, 50 and 75) and the frequency was 1 Hz and the energy was 600 mJ and at room temperature. We have used UV-visible spectroscopy, field emission scanning electron microscopy (FSEM), the EDX system, then these materials were added to the local dye and the photo-catalytic activity was applied to them using a UV-500 lamp for different periods of time (0, 30, 60 and 120 mint) and they acted as photo-catalysts.

Abstract: Metal oxide semiconductor has been widely used for breath analyzer applications. In this work, Acetone gas is the target gas as it an important breath marker for diabetes disease. Among the different p-type metal oxide nanostructures, Nickel oxide nanospheres are used as the sensing material as it is a promising candidate for Acetone sensing. The variation of resistance of the sensing material with the concentration of the target gas was analyzed. As Acetone is a reducing gas, the resistance of the sensing layer was found to increase when the sensing layer was exposed to the target gas. The simulation was done using COMSOL Multiphysics.

Abstract: This study focuses on the effect of deposition time and heat treatment on Ni₃Al coatings with respect to mechanical and microstructural properties of the material. Air plasma spraying technique was employed to deposit Ni₃Al on hot work tool steel samples for different deposition times i.e. 15-45 seconds. The coated samples were then heat treated at 900 °C for 20 to 100 hours at an interval of 20 hours each. The characterization tools such as X-Ray diffraction (XRD), optical and scanning electron microscopy (SEM) were used to study the homogeneity, phases formed and structure of coatings. All the coatings showed lamellar structure with distinctive boundaries along with the presence of some porosity and oxide particles. The XRD analysis of as prepared samples showed characteristic peaks of Ni₃Al whereas of heat treated samples revealed NiO formation that increased with increasing heat treatment time. Micro-hardness and wear resistance measurements of the coated layer showed that they were increasing with the deposition time due to formation of more thick and dense layers. Formation of NiO, due to heat treatment imparted greater hardness and wear resistance to the coating. Moreover, the SEM study of heat-treated samples showed presences of alumina and spinel phases which were confirmed by energy dispersive spectroscopic analysis.

Abstract: The reduction behaviour of cobalt doped with nickel oxide and undoped nickel oxide (NiO) by hydrogen (H₂) in nitrogen (20%, v/v) and carbon monoxide (CO) in nitrogen (40%, v/v) atmospheres have been investigated by temperature programmed reduction (TPR). The phases formed of partially and completely reduced samples were characterized by X-ray diffraction spectroscopy (XRD). TPR results indicate that the reduction of Co doped and undoped nickel oxide in both reductants proceed in one step reduction (NiO → Ni) without intermediate. TPR results also suggested that by adding Co metal into NiO, the reduction to metallic Ni by both reductant gaseous give different intensity of the peak. The reduction process of Co and undoped NiO become faster when H₂ was used as a reductant. Furthermore, in H₂ atmosphere, Co-NiO give complete reduction to metallic Ni at 700 °C. Meanwhile, XRD analysis indicated that NiO without Co composed better crystallite phases of NiO with higher intensity.

Abstract: This paper describes the reduction of nickel oxide under different gas mixture. The influence of gas mixture on phase, density, morphology and pore size of reduced nickel oxide were studied. Nickel oxide pellets sintered at 1400 °C were reduced under various hydrogen-nitrogen gas mixtures, namely 40% H₂-60% N₂, 60% H₂-40% N₂, 80% H₂-20% N₂. Phase identification, density measurement and observation of morphology were conducted on samples before and after reduction process. Under all gas mixtures, nickel oxide was completely reduced to nickel. Density of the samples decreased in the range of 21% to 32% depends on H₂ percentage used. Results from the density shows that the higher the H₂ gas concentration, the smaller the density changes. Significant change in porosity of the sample before and after reduction was observed. Size of pore after reduction determined by H₂ concentration used during reduction where the higher the H₂ concentration resulted in large pore size.