(644c) Geothermal Sludge-Derived Calcined Sodium Silicate As Heterogeneous Catalyst for Biodiesel Production from Waste Cooking OIL

Ichsan Dwi Nugraha

Department of Chemical Engineering, Institut Teknologi Sepuluh Nopember

ichsandwinugraha@gmail.com

Abstract - The depletion of world petroleum reserves and increased environmental concerns such as polluting air by emissions of sulfur dioxides, carbon dioxides, particulate matter, and other gases has resulted to increased research in alternate fuels and renewable source of energy. Trans-esterification process used to produce biodiesel from waste cooking oil, bears a large potential for the substitution of fossil diesel. Biodiesel is proved to be the best replacement for diesel because of its unique properties like significant reduction in greenhouse gas emissions, non-sulfur emissions, non-particulate matter pollutants, low toxicity and biodegradability. Therefore, the employment of waste oils as feedstock for biodiesel production are presented as the best alternative. The use of solid base catalyst in biodiesel production is becoming preferable because of their superiority advantages over the conventional homogeneous catalyst. Calcined sodium silicate is applied to catalyze trans-esterification reaction of vegetable oil with methanol. A strong base catalyst of sodium silicate synthesized from geothermal sludge of Dieng Geothermal Power Plant (Indonesia), which has 55% of silica content by gelation method. The factors affecting the process parameters reported are studied and the point of interest focuses on their catalyst both qualitative and quantitative scope, methanol to oil ratio, and reaction temperature. Sodium silicate catalyst was activated by calcination process at 400°C, temperature ramp of 20°C/min, and 3 hours detention time. The trans-esterification was carried out at various temperature in the range of 50°C - 70°C with a methanol-oil molar ratio of 9:1 and 3% (w/w) of catalyst for 60 minutes’ reaction time. To investigate kinetics of reaction, the sample were taken consecutively during the reaction after pouring into the reactor. Experimental results showed that the sodium silicate was very active in the trans-esterification of vegetable oil with methanol. Reaction temperature at 60°C was sufficient to reach a conversion level as high as above 94% in a relatively short reaction period. Results of the present work suggested that sodium silicate synthesized from local resources of geothermal sludge would become potential solid base catalyst in biodiesel synthesis.