Prof. Ir. Dr. Nor Aishah Saidina Amin

Abstract:

Immobilized titania (TiO₂) nanoparticles semiconductor on stainless steel mesh was used for photocatalytic conversion of CO₂ and CH₄. This study utilized experimental design and process optimization tools to maximize the desired response using response surface methodology (RSM) with central composite rotatable design (CCRD). The experimental parameters were stainless steel mesh size, titania nanoparticles loading, calcination temperature, UV light power and initial ratios of CO₂:CH₄:N₂ in feed. The optimal conditions were determined as follows: stainless steel mesh size of 140, 4 g of coated titania nanoparticles on mesh, calcination temperature of 600 °C, UV light power of 250 W and 10% of CO₂ in feed to achieve a maximum CO₂ conversion of 37.87%. Correspondingly, the selectivity of products were 4.66%, 4.28%, 3.97% and 87.09%, for ethane, acetic acid, formic acid and methyl acetate, respectively.

1. Saeed Delavari and Nor Aishah Saidina Amin (2015). Photocatalytic Conversion of Carbon Dioxide and Methane Over Titania Nanoparticles Coated Mesh_ Optimization Study: Optimization study, Energy Procedia, 61 (2014), 2485 – 2488. DOI: https://doi.org/10.1016/j.egypro.2014.12.028

Abstract:

Immobilized titania (TiO ₂ ) nanoparticles semiconductor on stainless steel mesh was used for photocatalytic conversion of CO ₂ and CH ₄ . This study utilized experimental design and process optimization tools to maximize the desired response using response surface methodology (RSM) with central composite rotatable design (CCRD). The experimental parameters were stainless steel mesh size, titania nanoparticles loading, calcination temperature, UV light power and initial ratios of CO ₂ :CH ₄ :N ₂ in feed. The optimal conditions were determined as follows: stainless steel mesh size of 140, 4g of coated titania nanoparticles on mesh, calcination temperature of 600°C, UV light power of 250W and 10% of CO ₂ in feed to achieve a maximum CO ₂ conversion of 37.87%. Correspondingly, the selectivity of products were 4.66%, 4.28%, 3.97% and 87.09%, for ethane, acetic acid, formic acid and methyl acetate, respectively.

1. Saeed Delavarai and NorAishah Saidina Amin (2015) Photocatalytic conversion of CO2 and CH4 over immobilized titania nanoparticles coated on mesh: Optimization and kinetic study, Applied Energy, 162, 1171-1185. DOI: https://doi.org/10.1016/j.apenergy.2015.03.125

Abstract:

Large number of studies related to alkali and acid catalyzed transesterification of waste cooking oil are widely available, but references for optimization and modeling comparison between single and two-step transesterification are scarce. Therefore, response surface methodology (RSM) has been employed to study the relationship between process variables and predict the optimal conditions. Sulfuric acid and sodium hydroxide were utilized in the pretreatment step and alkali catalyzed transesterification reaction, respectively. The highest free fatty acid (FFA) conversion in the two- and single-step reactions was 93.8% and 82.7%, respectively at the optimal reaction conditions being 1.1 wt% catalyst loading, 6.5:1 methanol to oil ratio, 60°C reaction temperature, and 65 min reaction time. .RSM could accurately predict the optimal FFA conversion in both two- and single-step processes by only 0.3% and 1.01% error, respectively. In addition, the two-step method produced higher fatty acid methyl ester (FAME) yield (86.7%) and also improved the final product quality compared to single-step method with only 73.7% biodiesel yield.

1. Amin Talebian-Kiakalaieh Nor Aishah Saidina Amin (2015) Single and Two-Step Homogeneous Catalyzed Transesterification of Waste Cooking Oil: Optimization by Response Surface Methodology. International Journal of Greenhouse Energy, Taylor & Francis, 12, 888-899. DOI: 10.1080/15435075.2014.884501

Abstract:

The low-temperature Fischer-Tropsch (LTFT) process aims to produce heavy cuts such as wax and diesel. For many years, there have been studies and improvements on the LTFT process to make the existing reactors more efficient. Recent studies have proposed innovative configurations such as monolithic loop and membrane reactors as well as microchannel reactor, which improved the performance of LTFT synthesis. This persuades us to update the existing knowledge about the available reactors. Some fundamental features of the current reactors, which belong to the classes of conventional reactors (fixed-bed reactors and slurry reactors) and innovative reactors, are discussed to assist the selection of the most efficient reactors specifically for heavy-cuts production. Published experimental and theoretical works with respect to developments in reactor technology and significant advances in catalysis (such as using structured packing, foams, and knitted wire as catalyst supports due to their excellent radial mixing properties) of the FT process are analyzed and discussed. Consequently, it is shown that the LTFT innovative reactors have higher CO conversions and selectivity of desired heavy cuts. Furthermore, the place of innovative reactors among conventional reactors in terms of effective process parameters on the product distribution has been estimated.

1. Samrand Saeidi, Maryam Khoshtinat Nikoo, Azadeh Mirvakili, Samaneh Bahrani, Nor Aishah saidina Amin, Mohammad Reza Rahimpour (2015). Recent advances in reactors for low-temperture Fischer-Tropsch synthesis: process intensification perspective. Reviews in Chemical Engineering, 31(3), 209-238. DOI: 10.1515/revce-2014-0042

Abstract:

In this study, CO₂ photoreduction via reverse water gas shift (RWGS) reaction over gold (Au) and indium (In) modified TiO₂ nanocatalysts in a monolith photoreactor has been investigated. Crystalline nanoparticles of anatase TiO₂ were obtained in doped TiO₂ samples with metals deposited over TiO₂ as Au and In³⁺ ions. The catalytic performance of metal-doped/TiO₂ catalysts was found to be considerably higher when compared to pure TiO₂. The maximum production of CO as the main product was 8982 μmol g-catal⁻¹ h⁻¹ at selectivity 99% and CO₂ conversion of 9.5% over 0.2 wt.% Au–3.5 wt.% In/TiO₂, and CO₂/H₂ feed ratio 1.5. The CO production over co-metals (Au–In) doped TiO₂ monolithic catalyst was 1.3 times higher than Au/TiO₂, 4.39 times higher than In/TiO₂ and 76 times higher than un-doped TiO₂ catalysts. Significantly higher photoactivity of metal-doped TiO₂ was obviously due to fast electron transfer with hindered recombination rates and larger illuminated surface area in monolith channels. The quantum efficiency of CO production through RWGS reaction using Au–In/TiO₂ catalyst was considerably improved (0.79%) than Au/TiO₂ (0.53%) and In/TiO₂ (0.14%) monolithic catalysts. The stability of the reused catalysts for CO production sustained at cyclic runs. This development confirmed higher performance of metals-doped TiO₂ nanocatalysts supported over monolith channels for CO₂photoreduction via RWGS reaction

1. Beenish Tahir, Muhammad Tahir and Nor Aishah Saidina Amin (2015). Gold–indium modified TiO2 nanocatalysts for photocatalytic CO2 reduction with H2 as reductant in a monolith photoreactor. Applied Surface Science, 338, 1-14. DOI: https://doi.org/10.1016/j.apsusc.2015.02.126

Abstract:

The gas phase dehydration of glycerol to acrolein over a series of supported silicotungstic acid (HSiW) on zirconia (10HZ, 20HZ, 30HZ and 40HZ) has been investigated. The catalysts were characterized by temperature programmed desorption, nitrogen adsorption–desorption, thermogravimetric analysis, Fourier transform infrared spectroscopy, X-ray diffraction, field-emission scanning electron microscopy and energy dispersive X-ray techniques. The large pore diameters (>19 nm) of the prepared catalysts alleviated the coke deposition effect. Also, the specific surface area and acidity of the samples surged from 18 to 22 m²/g and 0.38 to 1.24 mmol/g cat, respectively by varying HSiW loadings from 10 to 40 wt% on zirconia. The highest acrolein yield achieved was 63.75% at 92% glycerol conversion over 30HZ catalyst for 10 wt% glycerol feed concentration and 300 °C reaction temperature in 3 h. The combined physico-chemical characteristics of 30HZ made it more superior compared with other samples in the current study.

1. Amin Talebian-Kiakalaieh Nor Aishah Saidina Amin (2015) Supported silicotungstic acid on zirconia catalyst for gas phase dehydration of glycerol to acrolein Catalysis Today, pp 315-324. DOI: https://doi.org/10.1016/j.cattod.2015.01.045

Abstract:

The aim of this work was to study the potential of biofuel and biomass processing industry side-products as acid catalyst. The synthesis of carbon cryogel from lignin-furfural mixture, prepared via sol-gel polycondensation at 90°C for 0.5h, has been investigated for biodiesel production. The effect of lignin to furfural (L/F) ratios, lignin to water (L/W) ratios and acid concentration on carbon cryogel synthesis was studied. The carbon cryogels were characterized and tested for oleic acid conversion. The thermally stable amorphous spherical carbon cryogel has a large total surface area with high acidity. Experimental results revealed the optimum FAME yield and oleic acid conversion of 91.3wt.% and 98.1wt.%, respectively were attained at 65°C for 5h with 5wt.% catalyst loading and 20:1 methanol to oleic acid molar ratio. Therefore, carbon cryogel is highly potential for heterogeneous esterification of free fatty acid to biodiesel.

Muzakkir Mohammad Zainol, Nor Aishah Saidina Amin and Mohd Asmadi (2015) Synthesis and characterization of carbon cryogel microspheres from lignin furfural mixtures for biodiesel production. . Bioresource Technology, 190, 44-50. DOI: https://doi.org/10.1016/j.biortech.2015.04.067

Abstract:

Levulinic acid (LA) is a versatile chemical with numerous applications. In this study, the conversions of glucose and oil palm fronds (OPF) to LA have been conducted over 10% Fe/HY zeolite catalyst. The optimization of LA yield from glucose conversion using Box–Behnken design and response surface methodology reported 61.8% yield, which can be achieved at temperature 173.4 °C, reaction time 3.3 h, 0.93 g of glucose and 0.89 g 10% Fe/HY zeolite. The LA yield from OPF conversion conducted at the optimum conditions was 17.6% with 54.8% process efficiency. It was also observed that Fe leaching from 10% Fe/HY zeolite was insignificant and recycled 10% Fe/HY zeolite gave sufficient performance for five successive cycles. This study emphasizes the potential of Fe/HY zeolite catalyst for catalytic conversion of lignocellulosic biomass to LA.

1. Nur Aainaa Syahirah Ramli and NorAishah Saidina Amin (2015) Optimization of renewable levulinic acid production from glucose conversion catalyzed by Fe_HY zeolite catalyst in aqueous medium Energy Conversion Management, 95, 10-19. DOI: https://doi.org/10.1016/j.enconman.2015.02.013

Abstract:

The photocatalytic CO₂ reduction with H₂ over copper (Cu) and indium (In) co-doped TiO₂ nanocatalysts in a monolith photoreactor has been investigated. The catalysts, prepared via modified sol–gel method, were dip-coated onto the monolith channels. The structure and properties of nanocatalysts with various metal and co-metal doping levels were characterized by XRD, SEM, TEM, N₂ adsorption–desorption, XPS, and UV–vis spectroscopy. The anatase-phase mesoporous TiO₂, with Cu and In deposited as Cu⁺ and In³⁺ ions over TiO₂, suppressed photogenerated electron–hole pair recombination. CO was the major photoreduction product with a maximum yield rate of 6540 μmol g⁻¹ h⁻¹ at 99.27% selectivity and 9.57% CO₂ conversion over 1.0 wt% Cu–3.5 wt% In co-doped TiO₂ at 120 °C and CO₂/H₂ ratio of 1.5. The photoactivity of Cu–In co-doped TiO₂ monolithic catalyst for CO production was 3.23 times higher than a single ion (In)-doped TiO₂ and 113 times higher than un-doped TiO₂. The performance of the monolith photoreactor for CO production over Cu–In co-doped TiO₂ catalyst was 12-fold higher than the cell-type photoreactor. More importantly, the quantum efficiency of the monolith photoreactor was significantly improved over Cu–In co-doped TiO₂ nanocatalyst using H₂ as a reductant. The stability of the monolithic Cu–In co-doped TiO₂ catalyst for CO partially reduced after the third run, but retained for hydrocarbons.

1. Muhammad Tahir and Nor Aishah Saidina Amin (2015) Photocatalytic CO2 reduction with H2 as reductant over copper and indium co-doped TiO2 nanocatalysts in a monolith photoreactor Applied Catalysis A: General, 493, 90-102. DOI: https://doi.org/10.1016/j.apcata.2014.12.053

Abstract:

In this study a monolith photoreactor was compared with a cell type for testing photocatalytic CO₂ reduction with H₂ as a reducing agent. The monolith channels were dip-coated with TiO₂ nanoparticles and were characterized using XRD, SEM, BET and UV–Vis spectroscopy. The performance of monolith photoreactor for CO₂photoreduction was much higher in the presence of H₂ as a reducing agent than H₂O with cell density of 200 CPSI. The CO₂/H₂ molar ratio of 1.5 was optimum at which higher CO evolution was observed. The efficiency of monolith photoreactor in batch process for CH₄ production was 6 times higher than TiO₂ dispersed in a cell reactor. The production rates were in the following order: monolith-CH₄(69 μmole g⁻¹ h⁻¹) > monolith-CO (59 μmole g⁻¹ h⁻¹) > Cell-CH₄(12 μmole g⁻¹ h⁻¹) > Cell-CO (6 μmole g⁻¹ h⁻¹). The higher yield rates in monolith photoreactor were due to the larger illuminated surface area of its multiple microchannels and efficient light utilization compared to the cell type reactor. More importantly, the quantum efficiency for CH₄ production over TiO₂ supported monolith was much higher (0.042%) than the cell type reactor (0.0038%). The significantly improved quantum efficiency indicated higher photonic efficiency in the microchannel monolith photoreactor. On the other hand, CO was the main product in the continuous monolith photoreactor with lesser yield rate compared to a batch process. The higher yield rate in batch process was obviously due to accumulation of products over the entire reaction period. The reaction mechanism revealed that CO₂ was initially converted to CO before transforming to hydrocarbons at elongated time and in the presence of multi-electron processes.

1. Beenish Tahir, Muhammad Tahir and Nor Aishah Saidina Amin (2015). Performance analysis of monolith photoreactor for CO2 reduction with H2. Energy Conversion and Management, 90, 272-281. DOI: https://doi.org/10.1016/j.enconman.2014.11.018