(653a) Mixed Metal Oxide Loaded Nano Zsm-5 Catalyst For The Transesterification Of Soybean Oil With Methanol
Traditional fossil energy resources are limited. One of the promising approaches is the conversion of vegetable oils to biodiesel. Most of the commercial biodiesel is currently produced with caustic homogeneous base catalysts. Homogeneous processes are relatively fast, they still have significant purification costs due to caustic catalysts dissolved in the products. As an alternative insoluble and reusable heterogeneous catalyst, hydrotalcite (or mixed metal oxides: Zn/Al, Sn/Al) was evaluated for the heterogeneous transesterification of soybean oil with methanol. Recently, it is known that the actual active sites of the hydrotalcite are situated at the edges of the platelets. To synthesize smaller hydrotalcite crystallite is therefore beneficial to obtain more efficient catalyst. However, to utilize hydrotalcite in a slurry-phase process, it is advantageous to have mechanically strong catalyst particles available in the micrometer range to facilitate fast removal of the catalyst by filtration. Here, mixed metal oxides loaded on nano ZSM-5 was prepared for the purpose. The crystal morphology of nano-ZSM-5 was shown to have a large external surface area permeable to higher molecular weight substances by the addition of propyltrimethoxysilane into a conventional hydrothermal synthesis mixture. The resulted nano-ZSM-5 particle has the morphology of agglomerated small crystals of 20nm size. Mixed metal oxides were loaded on the nano-ZSM-5 by precipitation. The catalysts were tested in the transesterification of refined soybeanoil with methanol. The yield of fatty acid methylester was measured by using a GC-mass spectrometer. The catalytic activity of the mixed oxides loaded on nano-ZSM-5 showed higher activity than that of unloaded one. A yield of up to 80% was achieved in 4hr at 60°C. The performance data of the new catalyst under various operating parameters like temperature, concentration of reactants and catalyst will be discussed.