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Acidity characterization of heterogeneous acid catalysts and its role in biodiesel production

Mat, Ramli and Samsudin, Rubyatul Adawiyah and Mohamed, Mahathir (2009) Acidity characterization of heterogeneous acid catalysts and its role in biodiesel production. In: 2nd International Conference & Workshop on Basic & Applied Sciences and Regional Annual Fundamental Science Seminar (ICORAFFS 2009) , 2009, The ZON Regency Hotel, Johor.

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Abstract

Transesterification of triglycerides (TGs) with methanol is the central reaction in the synthesis of biodiesel from oils and fats. Commercially, this reaction is carried out using homogeneous base catalysts, which are corrosive and nonreusable but also produce neutralization waste, leading to increased costs and environmental concerns. Replacement of liquid homogeneous catalysts with solid heterogeneous catalysts would greatly solve problems associated with expensive separation protocols involved with the former, yielding a cleaner product and greatly decreasing the cost of synthesis. However research dealing with the use of solid acid catalysts for biodiesel synthesis has been limited due to pessimistic expectations about reaction rates and unfavorable side reactions. As part of ongoing efforts to investigate heterogeneous catalyst for biodiesel synthesis, a fundamental conversion of triglyceride and characterization of the catalyst in term of acidity was carried out for the transesterification of triacetin (a synthetic triglyceride in the liquid phase) with methanol on a number of solid acid catalysts. In this work, triacetin (the acetic acid triester of glycerol) was used as a model compound for TGs to provide fundamental insight into TG transesterification catalyzed by solid acid catalysts. Triacetin, having the same chemical functionality of any triglyceride molecule, shares the same reactivity principles of triglycerides. But triacetin differs from common TGs in terms of size. Therefore, this study should be considered an initial exploration of TG transesterification by solid acid catalyst. The solid acid catalysts studies were zirconia, sulfated zirconia, sulfated zirconia-alumina, tungsten zirconia, tungsten zirconia-alumina, sulfated tin oxide and zeolite ZSM-5. Liquid-phase reaction was performed at 60oC for 8 hours using a stirred batch reactor. Analysis of the samples was done using GCMS. NH3-TPD and IR-pyridine was used to characterize the acid sites concentration and strength of the solid catalyst. Determining the type of acid sites most active for transesterification is important. Catalyst characterization by powder X-ray diffraction allowed correlating the changes in catalyst structure. All these catalysts have high concentration of acid sites and showed great promise for biodiesel forming reaction. The conversion result using these solid catalysts was compared with their acidity in an effort to find the suitable solid acid catalyst and its role in biodiesel synthesis.

Item Type:Conference or Workshop Item (Paper)
Uncontrolled Keywords:transesterification, biodiesel, triacetin, acidity, acid site
Subjects:Q Science > QD Chemistry
Divisions:Chemical and Natural Resources Engineering (Formerly known)
ID Code:14718
Deposited By: Liza Porijo
Deposited On:12 Sep 2011 01:57
Last Modified:12 Sep 2011 01:57

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