Prof. Ir. Dr. Nor Aishah Saidina Amin

Abstract:

The performances of HZSM-5 and transition metal-loaded HZSM-5 (Mn, Cu, Fe, Ti) catalysts during catalytic ozonation of phenol have been investigated. It was observed the performance order for removal of phenol and COD was Mn/HZSM-5 > Fe/HZSM-5 > Cu/HZSM-5 > Ti/HZSM-5 > HZSM-5. The presence of metals on HZSM-5 enhanced the phenol removal capability of HZSM-5. Mn loading on HZSM-5 was optimized due to its high phenol removal capability amongst metal-loaded HZSM-5 catalysts. Experimental results suggested that low amount of Mn loading on HZSM-5 was sufficient for HZSM-5 to act as catalyst and adsorbent. A maximum of 95.8 wt% phenols and 70.2 wt% COD were removed over 2 wt% Mn/HZSM-5 in 120 min. It was supposed that transition metals mainly acted as ozone decomposers due to their multiple oxidation states that enhanced the ozonation of phenol.

1. Nor Aishah Saidina Amin, Javaid Akhtar and H.K. Rai (2011). Catalytic Ozonation of Aqueous Phenol Over Metal-Loaded HZSM-5. Water Science and Technology, 63 (8), 1651-1656, IWA Publishing. (2010 I.F =1.056)

Abstract:

Hydrothermal liquefaction is a technique for obtaining clean biofuel from biomass in the presence of a solvent at moderate to high temperature (250–550 °C) and pressure (5–25 MPa). Hydrothermal decomposition of biomass leads to the formation of various compounds depending upon operating parameters. The role of processing conditions including final liquefaction temperature, residence times, rate of biomass heating, size of biomass particles, type of solvent media and hydrogen donor solvents is important for the bio-oil yield and quality of the product. The effect of these parameters on the yield and composition of the liquid products is reviewed in the paper. A brief description about the decomposition mechanism is also included to highlight the product types during hydrothermal liquefaction.

1. Javaid Akhtar and Nor Aishah Saidina Amin (2011). A review on process conditions for optimum bio-oil yield in hydrothermal liquefaction of biomass. Renewable and Sustainable Energy Review, 15, 1615-1624, Elsevier. (2010 I.F = 4.567)

Abstract:

A thermodynamic equilibrium analysis on the multi-reaction system for carbon dioxide reforming of methane in view of carbon formation was performed with Aspen plus based on direct minimization of Gibbs free energy method. The effects of CO₂/CH₄ratio (0.5–3), reaction temperature (573–1473 K) and pressure (1–25 atm) on equilibrium conversions, product compositions and solid carbon were studied. Numerical analysis revealed that the optimal working conditions for syngas production in Fischer–Tropsch synthesis were at temperatures higher than 1173 K for CO₂/CH₄ratio being 1 at which about 4 mol of syngas (H₂/CO = 1) could be produced from 2 mol of reactants with negligible amount of carbon formation. Although temperatures above 973 K had suppressed the carbon formation, the moles of water formed increased especially at higher CO₂/CH₄ ratios (being 2 and 3). The increment could be attributed to RWGS reaction attested by the enhanced number of CO moles, declined H₂ moles and gradual increment of CO₂ conversion. The simulated reactant conversions and product distribution were compared with experimental results in the literatures to study the differences between the real behavior and thermodynamic equilibrium profile of CO₂ reforming of methane. The potential of producing decent yields of ethylene, ethane, methanol and dimethyl ether seemed to depend on active and selective catalysts. Higher pressures suppressed the effect of temperature on reactant conversion, augmented carbon deposition and decreased CO and H₂production due to methane decomposition and CO disproportionation reactions. Analysis of oxidative CO₂ reforming of methane with equal amount of CH₄ and CO₂revealed reactant conversions and syngas yields above 90% corresponded to the optimal operating temperature and feed ratio of 1073 K and CO₂:CH₄:O₂ = 1:1:0.1, respectively. The H₂/CO ratio was maintained at unity while water formation was minimized and solid carbon eliminated.

1. Maryam Khoshtinat Nikoo and Nor Aishah Saidina Amin (2011). Thermodynamic analysis of carbon dioxide reforming of methane in view of solid carbon formation.Fuel Processing Technology, 92, 678-691, Elsevier. (2010 I.F = 2.781)

Abstract:

Major problem in CO2 reforming of methane (CORM) process is coke formation which is a carbonaceous residue that can physically cover active sites of a catalyst surface and leads to catalyst deactivation. A key to develop a more coke-resistant catalyst lies in a better understanding of the methane reforming mechanism at a molecular level. Therefore, this paper is aimed to simulate a micro-kinetic approach in order to calculate coking rate in CORM reaction. Rates of encapsulating and filamentous carbon formation are also included. The simulation results show that the studied catalyst has a high activity, and the rate of carbon formation is relatively low. This micro-kinetic modeling approach can be used as a tool to better understand the catalyst deactivation phenomena in reaction via carbon deposition.

1. Istadi, Didi Dwi Anggoro, Nor Aishah Saidina Amin and Dorothy Hoo Wei Ling (2011). Catalyst Deactivation Simulation Through Carbon Deposition in Carbon Dioxide Reforming over Ni/CaO-Al₂O₃ Bulletin of Chemical Reaction Engineering and Catalysis, 6 (2), 129 – 136.

Abstract:

ZSM-5 zeolite is an acidic catalyst that is highly potential for the conversion of natural gas to liquid fuels. One of the variables that controls the acidity of the ZSM-5 is its Si/Al ratio. Loading the ZSM-5 zeolite with transition metals produces a catalyst with dual function – acidic and oxidative. These two functions need to be balanced to promote certain reactions such as dehydrogenation and oligomerization and to suppress the combustion reaction. The purpose of this study is to modify the ZSM-5 zeolite by substitution of aluminium in the zeolitic framework with an oxidative element, and test its performance for the conversion of methane to liquid fuels. Metal loaded dealuminated ZSM-5 zeolite was prepared by the acidic ion exchange method. Cr, Cu and Ga were chosen based on their role as a metal-oxide catalyst in reforming and dehydrogenation processes. The oxidation of methane was carried out in a micro-packed bed reactor at atmospheric pressure, 800°C, F/W = 10440 ml/g.hr and 9 vol% O2. The experimental results indicated that methane oxidation over the metal loaded dealuminated ZSM-5 produced gasoline with an encouraging Research Octane Number. The conversion of methane and the selectivity of gasoline obtained demonstrate that these catalysts have the potential to convert methane to C5+ liquid hydrocarbons.

1. Didi Dwi Anggoro and Nor Aishah Saidina Amin (2011). Methane to Liquid Fuels over Metal Loaded HZSM-5 Catalyst. Journal of Sustainable Energy & Environment, 2, 57 – 59.

Abstract:

This study examines the effect of pH of solution, cephalexin (CEX) concentration, and O3 dosage on removal of CEX by catalytic ozonation. All three parameters were found to exert a significant effect on the removal of cephalexin and on the enhancement in biodegradability of solution. The operating conditions were optimized using response surface methodology (RSM) and artificial neural network (ANN). Both RSM and ANN models were found capable of predicting removal of CEX during catalytic ozonation. Simultaneous optimization of two responses (chemical oxygen demand (COD) removal and CEX removal) was carried out using genetic algorithm based multiobjective optimization. Non-dominated Pareto optimal solutions provided the range of optimum conditions for the catalytic ozonation process. The optimized values of pH (9.7), ozone supply (34.5 mg/L), and CEX concentration (33.6 mg/L) using GA multiobjective optimization corresponded to complete conversion of CEX with 72% removal of COD.

1. Javaid Akhtar, Nor Aishah Saidina Amin and Wang Junjie (2012). Optimization Studies for Catalytic Ozonation of Cephalexin Antibiotic In A Batch Reactor, Journal of Water Supply: Research and Technology- AQUA, 61(7), 413-426, IWA Publishing (2011 I.F = 0.95)

Abstract:

This study is aimed at investigating the interactive effects of reaction parameters such as temperature (330–370 °C), total pressure (30–50 bar) and liquid hourly space velocity LHSV (1–3 h⁻¹) on the performance of hydrodesulfurization (HDS) activity. Experiments were performed based on the central composite rotatable design and analyzed using the response surface methodology (RSM). First, the equation model is used to predict HDS activity as a response. Second, the regression analysis of the HDS activity model is obtained from the output of this developed model. Finally, the RSM and canonical analysis is used to optimize this empirical regression model. R² = 96.5 % showed that the RSM model fitted the observed data well with and is considered to be accurate and available for predicting HDS activity. The obtained equation for the canonical analysis with different signs of eigenvalues revealed that the HDS activity at the stationary point was saddle-shaped. Numerical results also revealed that the maximum predicted HDS activity of 95.92 % was attained at the optimum reaction temperature of 383.63 °C, operating pressure of 56.81 bar and LHSV of 2.39 h⁻¹.

1. Fawzi M. Elfghi and Nor Aishah Saidina Amin (2012). Optimization of Hydrodesulfurization Activity in the Hydrotreating Process: Canonical Analysis and the Combined Application of Factorial Design and Response Surface Methodology. Reaction Kinetics, Mechanisms and Catalysis, 1-20, Springer Netherlands. (2011 I.F = 0.829)

Abstract:

Screening of modified ZSM-5 catalysts for conversion of glycerol to light olefins has been investigated. In this study HZSM-5, Al/ZSM-5, Ca/ZSM-5, Cr/ZSM-5, Cu/ZSM-5, Li/ZSM-5, Mg/ZSM-5 and Ni/ZSM-5 zeolite catalysts were prepared, tested and screened. The catalysts were characterized to relate their properties with catalyst activity. XRD and FTIR characterization results demonstrated that the structure of the catalysts remained intact while BET revealed the surface and micropore areas decreased after metal loading. TPR data exhibited the reduction phenomenon of the catalysts. NH₃-TPD analysis indicated that Cu/ZSM-5 catalyst has relatively more moderate and strong active acid sites compared to others. GC TCD/FID analysis detected light olefins and paraffins; methane, CO and CO₂ in the gaseous product stream. The acidity of the catalyst affected olefin production, but no direct correlation between surface area and olefin yield was observed. The turnover frequency (TOF) for Cu/ZSM-5 and Cr/ZSM-5 catalysts were significantly high comparatively. Cu/ZSM-5 produced the highest light olefins selectivity and yield due to the synergistic effect of the physico-chemical properties between the parent ZSM-5 and the metals.

1. Zaki Yamani Zakaria, Juhaa Linnekoski and Nor Aishah Saidina Amin (2012). Catalyst screening for conversion of glycerol to light olefins. Chemical Engineering Journal, 207-208, 803-813, Elsevier. (2011 I.F = 3.461)

Abstract:

Conversion of glucose, empty fruit bunch (efb) and kenaf to levulinic acid over a new hybrid catalyst has been investigated in this study. The characterization and catalytic performance results revealed that the physico-chemical properties of the new hybrid catalyst comprised of chromium chloride and HY zeolite increased the levulinic acid production from glucose compared to the parent catalysts. Optimization of the glucose conversion process using two level full factorial designs (2(3)) with two center points reported 55.2% of levulinic acid yield at 145.2 °C, 146.7 min and 12.0% of reaction temperature, reaction time and catalyst loading, respectively. Subsequently, the potential of efb and kenaf for producing levulinic acid at the optimum conditions was established after 53.2% and 66.1% of efficiencies were reported. The observation suggests that the hybrid catalyst has a potential to be used in biomass conversion to levulinic acid.

1. Nazlina Ya’aini, Nor Aishah Saidina Amin and Mohd Asmadi Mohd Yussuf (2012). Optimization of Levulinic Acid from Lignocellulosic Biomass Using a New Hybrid Catalyst. Bioresource Technology, 116, 58-65, Elsevier. (2011 I.F = 4.980)

Abstract:

Pyrolysis is one of the potential routes to harness energy and useful chemicals from biomass. The major objective of biomass pyrolysis is to produce liquid fuel, which is easier to transport, store and can be an alternative to energy source. The yield and composition of pyrolysis oil depend upon biomass feedstock and operating parameters. It is often necessary to explore about the effect of variables on response yield and instinct about their optimization. This study reviews operating variables from existing literature on biomass pyrolysis. The major operating variables include final pyrolysis temperature, inert gas sweeping, residence times, rate of biomass heating, mineral matter, size of biomass particle and moisture contents of biomass. The scope of this paper is to review the influence of operating parameters on production of pyrolysis oil.

1. Javaid Akhtar and Nor Aishah Saidina Amin (2012).A review on operating parameters for optimum liquid oil yield in biomass pyrolysis. Renewable and Sustainable Energy Review, 16(7), 5101-5109, Elsevier. (2011 I.F = 6.018)