Pengaruh Variasi Massa Katalis MgO/Mesopori Silika Hasil Impregnasi yang Digunakan pada Transesterifikasi Minyak Jarak

Abstract

The effect of MgO on the impregnation of mesoporous silica and its application as a catalyst in castor oil transesterification by varying the mass of catalyst used has been studied. Mesoporous silica was synthesized from tetraethylorthosilicate (TEOS) as a silica source and ricinoleate methyl ester as a template. In the impregnation process, mesoporous silica was mixed with Mg(NQ3)2.6H20 solution (as MgO 30%) and stirred for 8 hours at room temperature then dried in an oven and calcined at 65D°C for 8 hours. The resulting product was then applied as a catalyst in the transesterification of castor oil with variations in the mass of catalyst used, namely I%, 2%, 3% of the mass of castor oil. The reaction lasted for 4 hours at 65°C using methanol. The impregnated product was characterized by FT-IR, XRD, SEM-EDX and BET. FT-IR data showed the presence of silanol (Si-OH) and siloxane (Si-0-Si) groups which are characteristic of silica material and the appearance of absorption at wave number 408,91 cm-1 which is the peak of Mg-0 group. XRD data showed that the material was amorphous and had decreased intensity and shifted the main peak of the diffractogram towards a smaller 20 diffraction angle and the appearance of a typical peak of MgO at a 20 angle of 30,34°. SEM-EDX results supported the presence of MgO metal oxide formed. BET results showed a type IV isotherm curve and a type H3 hysteresis loop. The dominant pore size in silica material before and after impregnation was 14,27 nm and 15,4536 nm which belongs to the mesopore size of silica. Based on the data above, it can be concluded that the impregnation of MgO on silica material has been successful. The product of castor oil transesterification was characterized by FT-IR and GC-MS. The FT-IR spectrum showed the formation of ricinoleate methyl ester which was indicated by the appearance of stretching vibrations of the C-0-C group at wavenumber 1237,5 cm·1 , 1162,9 cm·1 and 1028,7 cm-1 . Based on the GC-MS results of the three variations, the best results were obtained on the MgO/MS 2% catalyst with ricinoleate methyl ester conversion of 83.09%.