Synthesis and characterization of mesoporous base catalyst for transesterification of palm oil

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Date
2009
Authors
Razali, Noraini
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Abstract
Due to environmental and economic concerns, current research trend in catalysis has been shifting from homogeneous into heterogeneous systems in which the active centers are supported on a solid. The pursuit of solid base catalyst has been recently focused on mesoporous silica substrates due to very high surface area, uniformity in pore size and hydrothermal stability which promising great opportunity for application as catalysts and catalytic supports. In the present study, SBA-15 (mesoporous material) was studied as a catalyst support. The synthesis of SBA-15 support was studied by varying different process parameters i.e. effects of reaction temperature, tetraethylorthosilicate/triblock copolymer (TEOS/TCP) ratio, pH of solgel solution and hydrothermal treatment time. The SBA-15 materials were subjected to surface analyzer, XRD, TEM and SEM in order to study BET surface area, crystallinity and morphology of the support, respectively. The optimum conditions for the SBA-15 were chosen based on the characterization results. The optimum conditions were obtained at 60 oC synthesis temperature, 1.52 TEOS/TCP ratio, pH 1.7 and 36 h of hydrothermal treatment time. Mesoporous base catalysts were developed by incorporating three different potassium compounds (KI, KNO3, KOH) loaded on SBA-15 by impregnation method with heating at a temperature of 350 oC for 3 h. All of these three types of catalyst were used in the transesterification process and the yield of FAME was investigated. The highest yield was obtained using KOH/SBA-15 catalyst and the optimum KOH loading was found to be at 20 wt. %. Otherwise, the different supports were also studied i.e. HZSM-5 and Al2O3. The optimization study of the transesterification process encompassed the effect of temperature (50-90 oC), methanol to oil ratio (6:1-14:1), weight of catalyst (1-5 wt. %) and reaction time (2-6 h). Response surface methodology (RSM) was employed for the optimization process to achieve the highest FAME yield and to evaluate the interaction between the parameters at the same time. The optimum conditions were found to give the best activity of 84.3 % of FAME yield at 70 oC of reaction temperature with a methanol to oil ratio of 11.6, 3.91 wt. % of catalyst and 4.54 h of reaction time. Besides showing high catalytic activity, KOH/SBA-15 could be reused for one more run with an activity drop of merely 15.6 %. Beside that, the catalyst also can be used in the transesterification process of waste cooking oil with 77 % of FAME yield. Furthermore, low activation energy of 46.37 kJ/mol was obtained for the transesterification process. From this study, it was demonstrated that the KOH/SBA-15 was an effective catalyst for the transesterification process of palm oil.
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Master
Keywords
Chemical science , Mesoporous base catalyst , Palm oil
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