Browsing by Author "Saharuddin T.S.T."
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Publication Chemical reduction behavior of zirconia doped to nickel at different temperature in carbon monoxide atmosphere(Gadjah Mada University, 2020) ;Dzakaria N. ;Abu Tahari M.N. ;Salleh F. ;Samsuri A. ;Azizi M.A.H. ;Saharuddin T.S.T. ;Yusop M.R. ;Isahak W.N.R.W. ;Hisham M.W.M. ;Yarmo M.A. ;Faculty of Science and Technology ;Universiti Kebangsaan Malaysia (UKM) ;Universiti Teknologi MARA (UiTM) ;Universiti Pertahanan Nasional Malaysia (UPNM)Universiti Sains Islam Malaysia (USIM)The reduction behavior of nickel oxide (NiO) and zirconia (Zr) doped NiO (Zr/NiO) was investigated using temperature programmed reduction (TPR) using carbon monoxide (CO) as a reductant and then characterized using X-ray diffraction (XRD), nitrogen absorption isotherm using BET technique and FESEM-EDX. The reduction characteristics of NiO to Ni were examined up to temperature 700 °C and continued with isothermal reduction by 40 vol. % CO in nitrogen. The studies show that the TPR profile of doped NiO slightly shifts to a higher temperature as compared to the undoped NiO which begins at 387 °C and maximum at 461 °C. The interaction between ZrO2 with Ni leads to this slightly increase by 21 to 56 °C of the reduction temperature. Analysis using XRD confirmed, the increasing percentage of Zr from 5 to 15% speed up the reducibility of NiO to Ni at temperature 550 °C. At this temperature, undoped NiO and 5% Zr/NiO still show some crystallinity present of NiO, but 15% Zr/NiO shows no NiO in crystalline form. Based on the results of physical properties, the surface area for 5% Zr/NiO and 15% Zr/NiO was slightly increased from 6.6 to 16.7 m2 /g compared to undoped NiO and for FESEM-EDX, the particles size also increased after doped with Zr on to NiO where 5% Zr/NiO particles were 110 ± 5 nm and 15% Zr/NiO 140 ± 2 nm. This confirmed that the addition of Zr to NiO has a remarkable chemical effect on complete reduction NiO to Ni at low reduction temperature (550 °C). This might be due to the formation of intermetallic between Zr/NiO which have new chemical and physical properties. - Some of the metrics are blocked by yourconsent settings
Publication Effect of rhodium additive on the reduction behaviour of iron oxide in carbon monoxide atmosphere [Kesan penambahan rodium terhadap tindak balas penurunan ferum oksida di dalam atmosfera karbon monoksida](Malaysian Society of Analytical Sciences, 2017) ;Saharuddin T.S.T. ;Salleh F. ;Samsuri A. ;Dzakaria N. ;Othaman R. ;Kassim M.B. ;Mohammad Hisham M.W. ;Yarmo M.A. ;Faculty of Science and Technology ;Universiti Sains Islam Malaysia (USIM) ;Universiti Kebangsaan Malaysia (UKM)Universiti Pertahanan Nasional Malaysia (UPNM)This study was carry out to investigate the effect of 3% rhodium on the reduction behaviour of iron oxide by (10%, v/v) carbon monoxide in nitrogen as a reductant. The Rh/Fe2O3 samples were prepared by impregnation method and the reduction behavior of Rh/Fe2O3 and pure Fe2O3 were investigated by using temperature programmed reduction (TPR). The prepared samples and the reduced phases were characterized by X-ray diffraction spectroscopy (XRD). The results indicate that Rh/Fe2O3 give a better reducibility compared to Fe2O3 with a complete reduction at 650 �C, which is 250 �C lower than Fe2O3. The TPR results indicate that the reduction of Fe2O3 proceed in three steps reduction (Fe2O3 ? Fe3O4 ? FeO ? Fe) with Fe3O4 and FeO as intermediate states while for Rh/Fe2O3 as the TPR result showed the overlapping of second and third peak (Fe3O4 ? FeO and FeO ? Fe) at higher temperature. Addition of Rh may possibly reduce the formation of stable FeO that stable at higher temperature by accelerates the direct reduction of Fe3O4? Fe so the reduction process of Fe2O3 become faster. The XRD pattern shows the diffraction peaks of Rh/Fe2O3 is more intense with improved crystallinity for the characteristic peaks of Fe2O3 compared to pure Fe2O3. No visible sign of rhodium particles peaks in the XRD spectrum that indicates the Rh particles loaded onto the iron oxide are well dispersed. The well dispersed Rh onto the iron oxide and the ability to reduce the sintering effect to the iron oxide also has been confirmed by FESEM. The study shows that addition of Rh gives a better reducibility of iron oxide is also due to the ability of Rh to interact with CO as confirmed by the thermodynamic data with higher surface area compared to Fe2O3. � 2017, Malaysian Society of Analytical Sciences. All rights reserved. - Some of the metrics are blocked by yourconsent settings
Publication Physical and chemical behaviour of tungsten oxide in the presence of nickel additive under hydrogen and carbon monoxide atmospheres(Elsevier Ltd, 2020) ;Salleh F. ;Tahari M.N.A. ;Samsuri A. ;Saharuddin T.S.T. ;Sulhadi S.S.Yarmo M.A.The physical and chemical behaviour of bulk tungsten oxide (WO3) and Ni doped tungsten oxide (15% Ni/WO3) were examined by performing a temperature-programmed reduction (TPR) technique. The chemical composition, morphology, and surface composition of both samples before and after reduced were analysed by X-ray diffraction (XRD), scanning electron microscopy (FESEM), and X-ray photoelectron spectroscopy (XPS) analysis. The XRD pattern of calcined Ni doped tungsten oxide powder comprised of WO3 and nickel tungstate (NiWO4) phases. The reduction behaviour was investigated by a non-isothermal reduction up to 900 °C achieved under (10 and 20% v/v) hydrogen in nitrogen (H2 in N2) and (20 and 40% v/v) carbon monoxide in nitrogen (CO in N2) atmospheres. The H2-TPR were indicated the reduction of bulk WO3 and 15% NiWO3 proceed in three steps (WO3 → WO2 → WO2 + W) and (WO3 → WO2 → W + Ni4W) respectively under 20% H2. Whereas, the reduction of 15% WO3 under 40% CO involves of two following stages: (i) low temperature (<800 °C) transformation of WO3 → WO2.72 → WO2 and, (ii) high temperature (>800 °C) transformation of WO2 → W → WC. Furthermore, NiWO4 alloy phase was transformed according to the sequence NiWO4 → Ni + WO2.72 → Ni + WO2 → Ni + W → Ni4W + W at temperature >700 °C and >800 °C in H2 and CO atmospheres, respectively. It can be concluded that the reduction behaviour of WO3 is matched with the thermodynamic data. In addition, the reduction under H2 is more favourable and have better reducibility compared to the CO gas. It is due to the small molecule size and molecule mass of H2 that encourages the diffusion of H2 molecule into the internal surface of the catalyst compared to CO. Moreover, Ni additive had improved the WO3 reducibility and enhancing the CO adsorption and promotes the formation of tungsten carbide (WC) by carburisation reaction. Besides, the formation of Ni during the reduction of 15% Ni/WO3 under CO reductant catalysed the Boudouard reaction to occur, which disproportionated the carbon monoxide to carbon dioxide and carbon (CO → CO2 + C). © 2020 Hydrogen Energy Publications LLC