Vol. 50 No. 7 2017 561 Copyright © 2017 The Society of Chemical Engineers, Japan Journal of Chemical Engineering of Japan, Vol. 50, No. 7, pp. 561–567, 2017 Utilization of Modified Red Mud as a Heterogeneous Base Catalyst for Transesterification of Canola Oil Agus Wahyudi 1,2 , Winarto Kurniawan 1 and Hirofumi Hinode 1 1 Department of International Development Engineering, Tokyo Institute of Technology, 2-12-1 O-okayama, Meguro-ku, Tokyo 152-8550, Japan 2 R&D Centre for Mineral and Coal Technology, Ministry of Energy and Mineral Resources, Jalan Jenderal Sudirman 623 Bandung, West Java 40211, Indonesia Keywords: Modifed Red Mud, Soda-lime Calcination, Solid Base Catalyst, Transesterifcation, Biodiesel The present study investigates the use of modified red mud as a solid base catalyst for biodiesel production. Red mud, a waste from the Bayer process, was treated using soda-lime calcination at various temperatures. The modified red mud was characterized using TG-DTA, XRD, SEM, BET and the Hammett indicator method. The catalytic activity was investi- gated for the transesterification of canola oil with methanol to biodiesel with a yield of more than 99% under the follow- ing conditions: 12 : 1 methanol/oil molar ratio, 4 wt% catalyst concentration, 60°C reaction temperature, and 2 h reaction time. Furthermore, the catalyst can be reused for up to three cycles without any significant loss of activity. Introduction Biodiesel is a promising renewable energy. It has many advantages, such as biodegradability, renewability, lower emissions, and compatibility with existing diesel engines (Helwani et al., 2009). One of the important factors to pro- duce biodiesel is the role of catalysts. Te homogeneous catalysts, such as sodium hydroxide and potassium hydrox- ide have been commercially used for biodiesel production with very high efficiency (Arzamendi et al., 2007). However, these catalysts have some limitations, such as difficulties in separation from the mixtures, resulting in large amount of wastewater for neutralization and low reusability (Georgo- gianni et al., 2009). To overcome these problems, hetero- geneous or solid catalysts were introduced. Tese types of catalysts have some advantages, such as high separability from mixture, reusability, and being environmentally benign due to fewer disposal problems (Semwal et al., 2011). Research on the development of solid catalysts, espe- cially from the view point of the application of waste mate- rials, have attracted attention to being explored. Te solid catalysts synthesized from waste materials, such as waste aluminium foil (Cherikkallinmel et al., 2015), mud clam shell (Ismail et al., 2016), sugarcane press mud (Aghabarari and Martinez-Huerta, 2016), and coconut husk ash (Vadery et al., 2014) have been developed to promote biodiesel pro- duction. By using those low-cost waste materials, not only the process could be made economical, but also an environ- mentally friendly process also could be promoted. Another waste material employed for biodiesel produc- tion was red mud (a waste from the Bayer process in the alu- mina industry). Liu et al. (2013) reported that red mud can be used as a basic catalyst for biodiesel production. Te cal- cined red mud was tested for its catalytic activity in several reaction conditions. However, the highest yield of biodiesel using this catalyst was still lower than the standard specifca- tion, although a high amount of methanol had been used (24 : 1 methanol/oil molar ratio). Te EN14214 standard stated that the product should meet the minimum biodiesel yield of 96.5% (Barabas and Todorut, 2011). In this work, red mud modifed by soda-lime calcina- tion was used as a solid base catalyst for transesterifcation of canola oil. Te effects of the methanol/oil molar ratio, catalyst amount, reaction temperature, and reaction time were studied to obtain the optimum reaction conditions. Te physical and chemical properties of the catalyst such as crystallinity, morphology, specifc surface area, thermogra- vimetry behavior, and basicity were also investigated. 1. Experimental 1.1 Catalyst preparation and characterization Te catalysts were prepared by modifcation of red mud through soda-lime calcination (Wahyudi et al., 2016). Red mud was obtained from the R&D Centre for Mineral and Coal Technology, the Ministry of Energy and Mineral Re- sources, Indonesia. Sodium carbonate was purchased from Wako Pure Chemical Industries, Ltd. Limestone (calcium carbonate) was obtained from an Indonesia local market. Te three components were mixed and ground at the molar ratio of Na 2 O/Al 2 O 3 and CaO/Si 2 O 3 of 1.5 and 2, respec- tively. Te mixed components were then sieved to obtain fne material with the particle size of 150 µm and labeled as RSL-uncalcined, where RSL is an abbreviation of the three components: red mud, soda and limestone. Otherwise, the Received on November 16, 2016; accepted on January 25, 2017 DOI: 10.1252/jcej.16we337 Correspondence concerning this article should be addressed to A. Wahyudi (E-mail address: a.wahyudi80@gmail.com). Research Paper