Papers by Author: Wan Nor Roslam Wan Isahak

Abstract: The priority of success in practical CO₂ capture with solid sorbents is dependent on the development of a low cost sorbent and energy consumption for regeneration with high adsorption capacity. In this work, different loading of NiO were evaluated as a potential source of basic sites for CO₂ capture, and activated carbon (AC) was used as a preliminary support in order to study the effect of the impregnation. The NiO loading increased the basicity of the adsorbent significantly enhance the CO₂ chemisorption. Nonetheless, it drastically reduced the surface area of the AC, which is chiefly responsible for CO₂ physisorption, thus decreasing the carrying capacity of ACs at room temperature and pressure.

Abstract: At room temperature, dehydrating agent, concentrated sulfuric acid (H₂SO₄) was used to form porous carbon (BAC) from bamboo waste shows good properties as CO₂ adsorbent. Selection of nano-CuO supported BAC produce composite materials with high total surface area and smaller pores size composite of 660.8 cm²/g and 2.7 nm. XRD data showed the support data to confirm the hydroxide phase formation as intermediate for carbonate and accelerate the CO₂ chemisorption reaction. Besides, the presence of BAC together with metal oxide can improve the CO₂ interaction physically on the surface and pores resulting the higher adsorption capability of 32.2 cm³ of CO₂ per gram adsorbent. The combination of nano-CuO on BAC become a good adsorbent which can stimulate the CO₂ reduction programme as well as reduce the CO₂ emissions during BAC production.

Abstract: A selective hydrogenolysis of glycerol has been attempted using an active nanosize and bulk size of Ru/FTO catalyst. The two approaches gives 1,2-propanediol as a main product. The higher conversion and selectivity was obtained at 99% and 94% for the bulky size of the catalyst, while nanosize catalyst give 89% of glycerol conversion and 97% 1,2-PDO selectivity. The Ru/FTO (7.5%) of metal loading, 150°C, 20 bar hydrogen pressure, and 8h was observed as an optimized reaction condition.

Abstract: Silica dioxide (SiO₂) can be modified by impregnating amine-containing compound to improve CO₂ adsorption capacity. Octadecylamine (ODA) was supported on silica dioxide particles. The amine-modified samples were characterized using FTIR, BET and XRD. Carbamate ion pair formation on surface of adsorbents was analyzed by XPS. Reactivity of solid sorbents towards CO₂ was evaluated using isothermal CO₂ adsorption by BET. This study shows 25 wt % ODA/SiO₂ can adsorb 2.45 wt % CO₂/adsorbent is slightly higher in adsorbing CO₂ compared to pure SiO₂ which only adsorb 1.85 wt % CO₂/adsorbent.

Abstract: In this paper the photocatalytic activity of TiO₂-PANi nanocomposites prepared using two different In-situ polymerization methods have been investigated. The same pressure, temperature, precursors, mole ratio, and solvent have been employed for preparation of nanocomposites. The synthesized nanocomposites were characterized by FESEM, XRD and FTIR. Results revealed the successful preparation of TiO₂- PANI nanocomposites. TiO₂-PANi nanocomposite synthesized using method 2 showed very well dispersed TiO₂ nanoparticles on the surface of PANi. There is no agglomeration of TiO₂ nanoparticles in PANi matrix. The photocatalytic activities of nanocomposites were evaluated by using photo degradation of Methylene Blue (MB) in aqueous solution under UV irradiation. These nanocomposites exhibit much higher photocatalytic activity compared with TiO_2.

Abstract: Activated carbon is produced from high cellulose containing biomass such as filter paper (FP), bamboo waste and palm empty fruit bunches (EFB) by dehydrating agent, concentrated sulfuric acid (H₂SO₄). At room temperature, treatment of H₂SO₄ is removed all the water molecules in the biomass and leaving only porous carbon without emitting any gaseous by-products. After activation by carbon dioxide (CO₂), Brunauer-Emmett-Teller (BET) and X-ray Diffractometer (XRD) analysis showed the bamboo activated carbon (BAC) has good properties with higher surface area (862.76 m²/g), micropore area (463.62 m²/g) and some crystalline (graphite) phase formation. Acid treatment of biomass has shown high carbon content for FP (85.30%), bamboo (77.72%) and EFB (76.55%), and yield obtained was 47.85 wt.% (FP), 62.4 wt.% (bamboo) and 55.4 wt.% (EFB) by using dehydration method.

Abstract: Recyclability effect on catalytic performance of Ru supported on the mixture of bentonite-TiO₂ for the hydrogenolysis of glycerol was investigated under reaction condition of 150°C, 2.0 MPa hydrogen pressure and 7 h reaction time. Interestingly, the recovered Ru/bentonite-TiO₂ catalyst was found to be active in the repeated runs. The conversion of glycerol increased in the four successive reactions as follows: 61.3%, 65.6%, 68.1% and 75.3%. This suggested that a sort of metal activation affect such as in situ reduction occurred during the repeated reaction. In order to confirm in situ reduction had occurred during the repeated reaction, XPS analysis of used catalyst after each reaction were carried out to study the chemical state of Ru 3d species. Narrow scan of peak Ru 3d revealed that intensity of Ru 3d_5/2 peak at BE 280.0 eV which is corresponding to Ru⁰ species increased until three cycle reaction. This result confirmed that in situ reduction had occurred during the repeated reaction and this made the activities of the catalyst increased upon recycling due to the availability of more metallic Ru on the surface of the catalyst. This study also shows that conversion of glycerol increased linearly with the percentage atomic ratio of Ru metal active site available on the surface of catalyst.

Abstract: Sol-gel silica-supported mineral acids (namely sol-gel perchloric acid (slg HClO₄), sulfuric acid (slg H₂SO₄) and phosphoric acid (slg H₃PO₄), prepared by incorporating mineral acids molecules into silica via sol-gel technique, were used as an efficient heterogeneous catalyst for the direct addition reaction of oleic acid (OA) to form estolides compound. The reactions were carried out under vacuum (2 mBar) for 10 hours at 70°C under solvent-less conditions. Liquid chromatography-mass spectrometry time of flight (LC-MS ToF) of reaction products results showed chromatographic peaks for the presence of two new estolide compounds, oleic-oleic monoestolide acid (m/z 563.51, as [M-^-), and oleic-oleic diestolide acid (m/z 845.77 [M-^-). The HClO sol-gel catalyst turned out to be the best catalyst, achieving a final conversion of 76.4% with 83.4% selectivity to oleic-oleic monoestolide acid (OOM) and 16.6% selectivity to oleic-oleic diestolide acid (OOD). The activity and selectivity of the mineral acid sol-gel catalysts have been investigated and compared with homogeneous HClO₄. The samples were characterised by XRD, TPD-NH₃ and XPS.

Abstract: In this work, we were study the selective synthesis of GME from oleic acid and glycerol using two types of solid heteropoly acid catalysts, namely silicotungstic acid bulk (STAB) and STA-silica sol gel (STA-SG). The performance and selectivity of STAB and STA-SG in the esterification reaction have been investigated and compared to the sulphuric acid (H₂SO₄) as conventional homogeneous catalyst. The catalysts were then characterized their physical and chemical properties using BET, XRD, TEM and XPS. XPS analyses were shown a significant formation of W-O-Si, W-O-W and Si-O-Si bonding in STA-SG compared to that in STAB. The main spectra of O1s (90.74 %, 531.5 eV) followed by other O1s peak (9.26 %, 532.8 eV) were due to the presence of W-O-W and W-O-Si bonds, respectively. The STA-SG catalyst was found to be the more environmentally benign solid acid catalyst for the esterification reaction between oleic acid and glycerol due to its lower toxicity in terms of the relatively lower pH value (pH 3.7) than the STAB (pH 2.8). In addition, the ease of separation for STA-SG catalyst was attributed to its insoluble state in the product phase. The esterification products were then analysed by FTIR and HPLC. Both the H₂SO₄ and the STAB gave high conversion of 100 % and 98 %, but at a lower selectivity of GME with 81.6% and 89.9%, respectively. On the contrary, the STA-SG enabled a conversion of 94 %, but with a significantly higher GME selectivity of 95 % rendering it the more efficient solid acid catalyst.

Abstract: Different catalysts, namely various loading of perchloric acid on various supports; HClO₄/silica (SiO₂), HClO₄/silica gel (SG) and HClO₄/alumina (Al₂O₃) were tested for the direct addition reaction of oleic acid (OA) to form estolide compounds. The reactions were carried out under vacuum (2 mBar) for 10 hours at 70 °C under solvent-less conditions. LC-MS ToF of reaction products results showed chromatographic peaks for the presence of two new estolide compounds, oleic-oleic monoestolide acid (m/z 563.51, as [M-H]^-), and oleic-oleic diestolide acid (m/z 845.77 [M-H]^-). The optimum loading of HClO₄ for every support are 15 wt.% HClO₄/SiO₂ (SiO₂15), 10 wt.% HClO₄/SG (SG10) and 35 wt.% HClO₄/Al₂O₃ (Al₂O₃35). The SG10 turned out to be the best catalyst, achieving a final conversion of 97.5 % with 79.8 % selectivity to oleic-oleic monoestolide acid and 17.7 % selectivity to oleic-oleic diestolide acid. The activity and selectivity of the SG10 have been investigated and compared with homogeneous HClO₄. The optimum catalysts for every support were characterized by XPS analysis, BET, TEM and TPD-NH₃.