OPTIMISATION OF SILICA/ALUMINUM MOLE RATIO FROM CYCLOTELLA STRIATA TBI BIOSILICA SHELL AS A RENEWABLE CATALSYT FOR ETHYL TERT-BUTYL ETHER PRODUCTION

• Main Author: Tuada Afnan, Nadia
• Format: Theses
• Language: Indonesia
• Subjects: Kimia
• Online Access: https://digilib.itb.ac.id/gdl/view/47725
• Institution: Institut Teknologi Bandung

Siliceous shell of Cyclotella striata TBI can be utilized as a silica source in synthesizing aluminosilicate catalysts. Catalytic properties of aluminosilicate originates from the substitution of tetravalent silica with trivalent aluminium, which forms Brønsted acid sites. The purpose of this research is to optimise the aluminium content within biosilica of C. striata TBI mixture as a catalyst in ethyl tert-butyl ether (ETBE) synthesis. Methods of this research includes cultivating C. striata TBI with batch method, isolating biosilica of C. striata TBI, synthesizing aluminosilicate by hydrothermal method, functionalization of aluminosilicate by protonation, and catalytic testing of ETBE synthesis. The result shows that cultivation of C. striata TBI for 14 days with initial cell density of 2×105 cell/mL generated 1.875 g/L of dry biomass. The morphology of C. striata TBI is cylindrical with a diameter of 10.53 µm. XRF analysis confirms that the SiO2 content in dry biomass of C. striata TBI is 100%. Biosilica properties was identified by FTIR, which shows Si–O–Si vibration bands at wave numbers of 450 and 1,111 cm–1. The disappearance of C–N vibration band at wave number of 1650 cm–1 indicates the removal of organic materials in C. striata TBI. Transformation of biosilica into aluminosilicate was confirmed by the emergence of Al–O–Si vibration bands at wave numbers of 555 and 1,222 cm–1, analyzed using FTIR. Formation of aluminosilicate was also confirmed by two double peaks at 2? between 7.8 until 8.9? and 23 until 23.9?, which are similar to crystalline ZSM–5 diffractograms. Aluminosilicate of C. striata TBI has a unique positive (+) shape with a diameter of around 0.87 µm. Within this research, aluminosilicate with Si/Al mole ratio of 2.64 was able to catalyze the reaction of ethanol and tert-butanol into ETBE, confirmed by GC–MS analysis showing a retention time of 2.11 minute. Based on mass spectrum, ion fragments (m/z) of 57, 59, and 87, which were ions of [C(CH3)3]+, [C(CH3)2COH]+, and [C2H5OC(CH3)2]+, were derived from ETBE fragmentations. Thus, C. striata TBI–based aluminosilicate can be utilised as a renewable catalyst in ETBE synthesis.