Prof. Ir. Dr. Nor Aishah Saidina Amin

Abstract:

Solar conversion of CO₂ to hydrocarbon fuels seems promising to reduce global warming for improved sustainability. Solar energy, as direct solar irradiations, is excessively available and it is imperious to utilize it for solar fuel production. This review paper is organized to discuss recent innovations and potential applications of phototechnology to recycle CO₂ via visible light responsive (VLR) TiO₂-based photocatalyst. In this perspective various enhancement methods such as doping with metals and non-metals and sensitization to expand TiO₂ band gap toward visible region are critically discussed. This review paper also presents applications of VLR photocatalysts, advances in photoreactors, and future prospects of VLR based technology for conversion of CO₂ to hydrocarbon fuels. The findings of this study revealed both metals and non-metals could improve TiO₂ photoactivity, but non-metals and especially co-metals were more efficient. The combination of co-metals with sensitizers exhibited much higher CO, CH₄ and CH₃OH yield rates. Among photocatalytic reactors, optical fibers and monolith photoreactors are more efficient because of their efficient light harvesting potential. Although the progress in CO₂reduction to fuels is encouraging, further considerations are required for commercialization purposes.

1. Muhammad Tahir and Nor Aishah Saidina Amin (2013). Advances in visible light responsive titanium oxide-based photocatalysts for CO2 conversion to hydrocarbon fuels.Energy Conversion and Management, 76, 194-214, Elsevier. (2012 I.F = 2.775)

Abstract:

In this study, the performance of a montmorillonite (MMT)/TiO₂ coated monolith photoreactor was tested for the photocatalytic CO₂ reduction. CH₄ and CO were the main products having yield rates of 139 and 52 μmole g catal.⁻¹ h⁻¹, respectively. The other adequately significant products were C₂H₄, C₂H₆, C₃H₆ and C₃H₈. The catalytic reactor performance for CH₄ production was in the order of MMT–TiO₂–monolith (139 μmole g catal.⁻¹ h⁻¹) > TiO₂–monolith (82 μmole g catal.⁻¹ h⁻¹) > MMT–TiO₂–cell (43 μmole g catal.⁻¹ h⁻¹) > TiO₂–cell (7.7 μmole g catal.⁻¹ h⁻¹). The higher yield rates in monolith photoreactor were due to the higher illuminated surface area and efficient light utilization. In addition, the profound hydrocarbon yield rates over MMT/TiO₂ nanocatalyst supported microchannels were due to the efficient production and utilization of charges. The reaction rate and the adsorption–desorption phenomenon was postulated according to the Langmuir–Hinshelwood (L–H) model. A simple kinetic equation, derived to model the coupled effect of adsorptive photocatalytic reduction and oxidation, fitted-well with the experimental data.

1. Muhammad Tahir and Nor Aishah Saidina Amin (2013). Photocatalytic CO2 reduction with H2O vapors using montmorillonite_TiO2 supported microchannel monolith photoreactor. Chemical Engineering Journal, 230, 314-327, Elsevier. (2012 I.F = 3.461)

Abstract:

Response surface methodology (RSM) has been used to optimize the effect of circulation rates, ozone supply, cephalexin (CEX) concentration, and granular activated carbon (GAC) dose on removal of COD from solution. According to statistical analysis, all of the input variables exerted significant influence on COD removal, however, the effect of interaction variables was not found to be significant on comparative basis. Further, the developed quadratic regression model based on obtained results emphasized the significance of individual terms and little of interaction terms. The values of r2 (0.959), adjusted r2 (0.902) obtained by analysis of variance (ANOVA) indicates the significance of quadratic model in predicting desired response. The maximum of 70% of COD was removed in these experiments and optimized value according to main effect of variables was 60%.

1. Javaid Akhtar, Nor Aishah Saidina Amin and Zahoor, M.K (2013).Optimizing Removal of COD from Water by Catalytic Ozonation of Cephalexin using Response Surface Methodology Journal of the Chemical Society of Pakistan 35(5), 1249-1253.

Abstract:

Montmorillonite (MMT) modified TiO₂ nanocomposites were synthesized by single step sol–gel method. The samples were characterized by XRD, FE-SEM, HR-TEM, FT-IR, N₂-adsorption–desorption, UV–vis and photoluminescence (PL) spectroscopy. Modification of TiO₂ with MMT controlled the crystal growth and produced anatase phase of delaminated TiO₂ pillared montmorillonite. The size of TiO₂ nanoparticles reduced from 18.73 to 13.87 nm after adding MMT, while the surface area and pore volume increased. The UV–vis results identified blue shift in TiO₂ band gap for the MMT modified samples. In addition, PL spectroscopy revealed significant inhibition in recombination of photogenerated electron–hole pairs. The performance of MMT modified TiO₂ samples for reducing CO₂ with H₂O to hydrocarbon fuels was investigated. The effects of parameters such as MMT loading on TiO₂, H₂O/CO₂ feed ratios, and reaction temperature on TiO₂ photocatalytic activity was studied. Loading MMT on TiO₂ enhanced the performance of TiO₂ and markedly increased CO₂reduction to C₁–C₃ hydrocarbon fuels. The highest yield rates produced were 441.5 and 103 μmol g cat⁻¹ h⁻¹ for CH₄ and CO, respectively under UV light irradiations at 20 wt.% MMT loading, reactor pressure of 0.20 bars and 393 K reaction temperature. These results revealed silicate layers of MMT dispersed in the given TiO₂ sol system and vacant d-orbits of the MMT transition metal ions have obvious effect on the photocatalytic activity of TiO₂. The possible pathways and reaction mechanisms of CH₄ and CO productions were also suggested. Thus, MMT is a potentially attractive material to improve TiO₂ as a photocatalyst for application in photocatalytic CO₂reduction.

1. Muhammad Tahir and Nor Aishah Saidina Amin (2013). Photocatalytic reduction of carbon dioxide with water vapors over montmorillonite modified TiO2 nanocomposites Applied Catalysis B: Environmental, 142-143, 512-522, Elsevier. (2012 I.F = 5.825)

Abstract:

Energy crisis and threats of global warming has accelerated the thrust for new renewable energy resources. Recycling greenhouse gases seems eminently potential to produce sustainable fuels as well as to reduce carbon emission. Various possibilities for implementing low carbon economy drive by practicing phototechnology are reviewed in this paper. In particular, different challenges and applicable solutions for efficient and economical conversion of greenhouse gases to renewable fuels are discussed. The roles of key parameters such as types of reductant, reduction potential, pH of mixture, metal-loaded and supported catalyst on hydrocarbon yield and selectivity are also investigated. Various types of photoreactors and different challenges in the design are also elaborated. It was obvious that modification of semiconductor photocatalyst, optimum operating parameters and suitable photoreactor design are pertinent for efficient CO₂ reduction to sustainable hydrocarbon fuels. In view of the current scenario, there are ample opportunities for producing renewable fuels and establishing a sustainable carbon neutral cycle using phototechnology.

1. Muhammad Tahir and Nor Aishah Saidina Amin (2013). Recycling of Carbon Dioxide to Renewable Fuels by Photocatalysis: Prospects and Challenges. Renewable and Sustainable Energy Reviews, 25, 560-579, Elsevier. (2012 I.F = 5.627)

Abstract:

The synthesis of fatty acid ethyl esters (FAEEs) by a two-step in situ (reactive) esterification/transesterification from Jatropha curcas L. (JCL) seeds using microwave system has been investigated. Free fatty acid was reduced from 14% to less than 1% in the first step using H2SO4 as acid catalyst after 35min of microwave irradiation heating. The organic phase in the first step was subjected to a second reaction by adding 5N KOH in ethanol as the basic catalyst. Response surface methodology (RSM) based on central composite design (CCD) was utilized to design the experiments and analyze the influence of process variables (particles seed size, time of irradiation, agitation speed and catalyst loading) on conversion of triglycerides (TGs) in the second step. The highest triglycerides conversion to fatty acid ethyl esters (FAEEs) was 97.29% at the optimum conditions:<0.5mm seed size, 12.21min irradiation time, 8.15ml KOH catalyst loading and 331.52rpm agitation speed in the 110W microwave power system.

1. Hamidreza Jaliliannosrati, Nor Aishah Saidina Amin, Amin Talebian-Kiakalaieh and Iman Noshadi (2013). Microwave Assisted Biodiesel Production from Jatropha Curcas L. Seed by Two-Step In Situ Process: Optimization using Response Surface Methodology. Bioresource Technology, 136, 565-573, Elsevier. (2012 I.F = 4.750)

Abstract:

Glycerol, an alcohol and oxygenated chemical from biodiesel production, has enormous potential to be converted into higher value-added fuels and chemicals. Conversion of glycerol to olefins, although relatively new, has been proven viable by the limited number of literatures available. However, the studies on alcohol-to-hydrocarbons involving methanol and ethanol conversions to hydrocarbons (MTHC and ETHC) have extensively been conducted. Due to the increasing amount of glycerol produced worldwide and the importance of olefins in the industry, it is therefore essential to have broadened knowledge on the technology of glycerol conversion to olefin (GTO). This review focuses on GTO with reference to the more established MTHC and ETHC studies. The chemistry and reaction schemes for methanol and ethanol reactions to produce hydrocarbons are also reviewed to provide some basics study for GTO. Catalytic conversion processes with different raw materials for obtaining olefins are then compared with GTO. GTO offers viable, sustainable and environmental friendly technology for green olefins production from renewable resources, and concerted efforts should be geared to explore its potential.

1. Zaki Yamani Zakaria, Nor Aishah Saidina Amin and Juhaa Linnekoski (2013). A perspective on catalytic conversion of glycerol to olefins. Biomass and Bioenergy, 55, 370-385, Elsevier (2012 I.F = 2.975)

Abstract:

In this work, a set of hybrid catalysts were synthesized, characterized and tested for the conversion of glucose to levulinic acid. The hybrid catalysts with 1:1, 1:2 and 2:1 weight ratios of CrCl₃ and HY zeolite were prepared via the wetness impregnation method. Characterization of the hybrid catalysts using XRD, FESEM, BET, FT-IR, TGA, NH₃-TPD and FT-IR of adsorbed pyridine demonstrated the catalytic reaction of the hybrid catalysts was predominantly influenced by the type of acid sites (Lewis acid), amount of acid sites and strength, surface area, hierarchical porous structures and shape selectivity. Highly reactive acid sites greatly influenced the catalytic activities of glucose in producing levulinic acid. Experimental results revealed that the hybrid 1:1 catalyst exhibited the highest catalytic performance with 62% of levulinic acid yield at 160 °C in 180 min of reaction temperature and time. The hybrid 1:1 catalyst has potential to be applied for biomass conversion to levulinic acid under adequate process conditions.

1. Nazlina Ya’aini, Nor Aishah Saidina Amin and Salasiah Endud (2013).Characterization and performance of hybrid catalysts for levulinic acid production from glucose. Microporous and Mesoporous Materials, 171, 14-23, Elsevier. (2012 I.F = 3.365)

Abstract:

5-Hydroxymethylfulfural (5-HMF) is a versatile compound obtained from renewable resources such as agricultural residue and biodegradable waste. 5-HMF has potentials to replace fuel-based petroleum and fine chemicals. Glucose, a monosaccharide is often used as a model compound to produce 5-HMF from biomass material. This study focused on glucose dehydration to produce 5-HMF by using ytterbium triflate and [BMIM]Cl as catalyst and solvent, respectively. Response surface methodology (RSM) based on central composite design (CCD) was employed to investigate effect of important process parameters and to optimize glucose dehydration process. The interaction effects between reaction temperature, time and catalyst loading towards 5-HMF yield was discussed. Effect of temperature was profoundly significant on the yield. The optimum conditions for dehydration of glucose for reaction temperature = 105 °C, reaction time = 2.7 h and catalyst loading = 39.7 mg obtained 52% of 5-HMF yield.

1. Sylvia Putri Utami and Nor Aishah Saidina Amin (2013). Optimization of Glucose Conversion to 5-Hydroxymethylfulfural using [BMIM]Cl with Ytterbium Triflate. Industrial Crops and Products, 41, 64-70, Elsevier. (2012 I.F = 2.468)

Abstract:

Fossil fuel depletion, environmental concerns, and steep hikes in the price of fossil fuels are driving scientists to search for alternative fuels. The characteristics of biodiesel have made the pursuit of high quality biodiesel production attractive. Utilization of waste cooking oil is a key component in reducing biodiesel production costs up to 60–90%. Researchers have used various types of homogeneous and heterogeneous catalyzed transesterification reaction for biodiesel production. Meanwhile, the effect of novel processes such as membrane reactor, reactive distillation column, reactive absorption, ultrasonic and microwave irradiation significantly influenced the final conversion, yield and in particular, the quality of product. This article attempts to cover all possible techniques in production of biodiesel from waste cooking oil.

1. Amin Talebian-Kiakalaieh, Nor Aishah Saidina Amin and Hossein Mezaheri (2013).A review on novel processes of biodiesel production from waste cooking oil.Applied Energy, 104,683-710. Elsevier. (2012 I.F = 4.781)