Abstract:
X zeolite, Y zeolite and SBA-15 were synthesized via microwave method. The influence of synthesis time on catalyst formation was varied from 0.5 to 4.0 hrs to compare with hydrothermal method. The gel molar composition of Y zeolite was 13.41 SiO2: 5.41 Na2O: Al2O3: 171 H2O. In case of X zeolite Si/Al molar ratio was changed to 1.5-2.5 with constant for other compositions as Y zeolite synthesis. In addition, the gel molar composition of SBA-15 was 1.0 TEOS: 0.0165 P123: 6.95 HCl: 140 H2O. From the experimental results, the microwave irradiation could reduce synthesis time which was faster than synthesized by hydrothermal method. After that, synthesized materials could be acid-modified by propyl sulfonic grafting. The acidic porous samples were characterized by X-ray powder diffraction, nitrogen sorption analysis, scanning electron microscopy, sulfur elemental analysis and ammonia temperature programmed desorption techniques. All synthesized catalysts were applied in esterification of oleic and palmitic acid with methanol to produce fatty acid methyl ester (biodiesel). The various reaction conditions such as catalyst amount, methanol to free fatty acid mole ratio, reaction time and temperature were studied. From the results, the optimum conditions for SBA-15-SO3H catalyst were methanol to oleic acid molar ratio of 12, amount of catalyst to reactant weight ratio of 3 wt% at 60°C for 1 hr which gave the maximum methyl oleate yield as 98.14%. On the other hand, acidic microporous materials were required more vigorous condition which gave methyl oleate yield as 80% and 76.72% for the sulfonic functionalized Y and X zeolite, respectively.
