Modification of Gresik's dolomite to CaO•MgO nanocomposite as a catalyst for synthesis of biodiesel from tamanu oil

Synthesis of biodiesel from tamanu oil is accomplished using a CaO•MgO nanocomposite catalyst obtained through Gresik's dolomite modification. The latter process refers to calcination at 850°C and co-precipitation using a solution of 2 N HNO₃ and 2 N NaOH. The characteristics of CaO•MgO are identified by XRD, while the base strength is determined by using Hammett indicators. It is found that the catalyst has a maximum diameter of 52.99 nm (nanocrystal size), while the strength of the base sites is in the range of 7.2 < H- < 15.0. The maximum catalyst activity of CaO•MgO in respect to the transesterification reaction is reached at 65°C and a methanol to oil molar ratio of 1: 30. The study follows also the effect of the catalyst amount variation (0.5 g, 1.0 g and 1.5 g) with varying the reaction time (1 h, 2 h, 3 h, 4 h and 5 h). The conversion of tamanu oil into a biodiesel is determined by GC-MS. It is found that conversion of up to 97.96 % is achieved for 5 h.