FUEL 36 |
| Biodiesel is a renewable fuel that is typically made by base-catalyzed transesterification of an oil or fat to simple fatty acid esters. The cost of the feedstock (e.g., soybean oil) is the major factor in producing biodiesel. High fatty acid-containing feedstocks such as yellow and brown greases are readily available, inexpensive, and renewable resources and hence are attractive feedstocks for the production of biodiesel. The high free fatty acid (FFA) content of these feedstocks, however, makes it difficult to produce biodiesel using base-catalyzed transesterification. A promising approach is to add an acid pretreatment step in order to reduce the FFA content in the greases to <1 wt% prior to alkali transesterification. However, the need of using a large amount of base to neutralize the acid catalyst remaining in the pretreated greases in this two-step process increases the production cost of BD from greases. We have developed several approaches to immobilizing highly acidic diarylammonium catalysts onto mesoporous silica materials and crosslinked poly(divinylbenzene) matrices. These recyclable and reusable heterogeneous diarylammonium catalysts are highly effective in catalyzing the esterification of the FFA present in greases to methyl esters to reduce the FFA content from 12-40 wt% to <1 wt%. The resulting ester-glyceride mixture (pretreated grease) could then be readily converted to methyl esters by base-catalyzed transesterification. We have thus developed a highly efficient two-step process for the production of biodiesel in >99% yield from readily available, inexpensive, and renewable high FFA-containing feedstocks. |
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BioFuels: Biodiesel Chemistry and Implementation
1:25 PM-6:00 PM, Sunday, August 19, 2007 Boston Park Plaza -- Arlington Rm, Oral
Sci-Mix
Division of Fuel Chemistry |