Silicotungstic Acid Anchored to Mesoporous Siliceous Support as a Catalyst for Production of Biodiesel
Authorde Souza, Kimberley Joann
Materials Science and Engineering
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The transportation sector, in the past 30 years has seen a significant growth commensurate with the economic development of several nations worldwide. This sector, like many others, relies heavily on liquid-based fossil fuels namely petroleum and to a small extent natural gas. Global reserves and supply of these fuels is dwindling at an alarming rate due to indiscriminate usage. Moreover, extraction of these resources leads to significant environmental degradation. In addition to the vast quantities of greenhouse gases (GHGs) are being released into the atmosphere as a result of the combustion offossil fuels. Therefore, it is desirable to find suitable, sustainable, economically feasible and more importantly environmentally-friendly extenders or alternatives to combat this multifaceted problem.The present study explores the use of a silico tungstic acid (STA) anchored to mesoporous siliceous support as a catalyst to produce biodiesel, a well-known carbon neutral, renewable fuel. Silicotungstic, which is a heteropoly acid (HPA) and a Brönstedacid, has high thermal stability and displays pseudo liquid behavior due to its highly mobile ions. However, its inherent solubility in polar media coupled with its low porosity>10m<super>2</super>/g have discouraged its use as a catalyst. In this study, the silicotungstic acid wasloaded on a mesoporous siliceous support KIT6 at increasing loading levels of 10%-30% STA. The catalysts were characterized using Brauner, Emmett and Teller method (BET) surface area analysis to obtain information regarding porosity and surface area and scanning electron microscopy (SEM) imaging for surface morphology. These materials were then used to catalyze a reaction between methanol and used cooking oil. The conditions for the reaction used were: 1.5 w/w catalyst to oil ratio, 1:2 v/v oil to methanolratio, temperature was maintained at 60<super>O</super>C for 6 hours of reaction time with constant agitation. The resulting products were analyzed using gas chromatography mass spectrometry to determine presence of fatty acid methyl esters (FAME). Acid number and conversion of free fatty acids to FAME was determined using titration. The experiments showed that 30%STA on KIT6 led to 84.2% conversion of used cooking oil to biodiesel.