Research On Biodiesel Preparation By Sugar-based Solid Acid Catalyst

Biodiesel consists of fatty acid alkyl esters produced by esterification or transesterification of vegetable oils, animal fats or waste oils with short chain alcohols and is a biodegradable, nontoxic, cleaning and renewable fuel, which is expected as a part of substitute for conventional fossil diesel. The cost problem of material is the key factor that restricts the development of biodiesel line. So seeking one kind of cheap material is one of the direction to study, too. Waste oils and fats will meet the need to synthesize biodiesel because of its sleazy price and broad source. Waste oils and fats used to synthesize biodiesel, are not only able to resolve the problem that the impact of waste oils and fats to safety of food, but also to the problem of exorbitant cost of material. The waste oils and fats are selected and used to produce biodiesel by combining deacid value and esterification technology.Waste cooking oil quality was extremely poor and very unhygienic. Its peroxide value, acid value and mowasture were beyond the limit seriously. It was occupied by a lot corruption factor, aspergillus flavus and unclean substances, so it was a great danger to persons after its consumption. Waste cooking oil returning to the table, let people talk with a changed look.In this paper, a low cost catalyst which is more suitable for synthesizing biodiesel using waste edible oils and fats with high acid value is studied. This catalyst which using glucose as raw materials, is a new type of carbon-based catalyst, loaded with sulfonate groups. The methods of preparation of carbon-based catalyst are direct heating method and hydrothermal method. My study shows that direct heating of the carbon material prepared bulk, large size, unevenly distributed catalyst; while spherical catalystes with uniform particle size are synthesized by hydrothermal preparation. Both catalyst prepared by direct heating and hydrothermal method have high acid density values, but the catalyst prepared by direct heating is less stable, while the catalyst prepared by hydrothermal synthesis has better catalytic activity and stability.In the study of biodiesel synthesis, vegetable oil as the raw material for biodiesel is firstly considered. At the same time, the catalytic activity and stability of these two kinds of catalyst are studied. We found that the catalyst prepared by direct heating is less stable, while the catalyst prepared through hydrothermal process is still in high catalytic activity even after seven times uses. The best conditions for biodiesel preparation from vegetable oil using catalyst through hydrothermal process are as follows: methanol to oil molar ratio equals 6, 10 hours for reaction, 4% of oil mass use for catalyst, reaction temperature 170℃. Under this condition of preparation, the yield of methyl ester reaches to 89.64%.The best conditions for biodiesel preparation from waste cooking oil using catalyst through hydrothermal process are as follows: methanol to oil molar ratio equals 6, 10 hours for reaction, 4% of oil mass use for catalyst, reaction temperature 170℃. Under this condition of preparation, the yield of methyl ester reaches to 83.57%.