Abstract: The present invention relates to a process for preparing a bio-diesel, comprising the steps of, in the presence of an additional free fatty acid source, reacting a raw oil-fat with C1-C6 monohydric alcohol in a reactor, and separating fatty acid esters from the reacted materials, so as to produce the bio-diesel, wherein the amount of the free fatty acid in the free fatty acid source ranges from 2-100 wt % and is higher than the amount of the free fatty acid in the raw fat-oil. The present process can increase the fatty acid ester yield and purity of raw oil-fats having a low reaction activity, and has a high adaptability to raw materials.

Abstract: The present invention provides a process for preparing a bio-diesel, comprising, in the presence of an alkaline metal compound, reacting an oil-fat with C1-C6 monohydric alcohol in a reactor at a reaction temperature of from 130 to 280° C. and a reaction pressure of from 1 to 12 MPa, separating fatty acid esters from the reacted materials, so as to produce the bio-diesel, wherein said alkaline metal compound is present in an amount of 0.001-0.07 wt %, in terms of the metal thereof, relative to the weight of the oil-fat. The process provided in the present invention has the advantages of great throughput and high yield of the bio-diesel.

Abstract: The present invention provides a process for preparing a bio-diesel, comprising, in the presence of an alkaline metal compound, reacting an oil-fat with C1-C6 monohydric alcohol in a reactor at a reaction temperature of from 130 to 280° C. and a reaction pressure of from 1 to 12 MPa, separating fatty acid esters from the reacted materials, so as to produce the bio-diesel, wherein said alkaline metal compound is present in an amount of 0.001-0.07 wt %, in terms of the metal thereof, relative to the weight of the oil-fat. The process provided in the present invention has the advantages of great throughput and high yield of the bio-diesel.

Abstract: The present invention relates to a process for preparing a bio-diesel, comprising the steps of, in the presence of an additional free fatty acid source, reacting a raw oil-fat with C1-C6 monohydric alcohol in a reactor, and separating fatty acid esters from the reacted materials, so as to produce the bio-diesel, wherein the amount of the free fatty acid in the free fatty acid source ranges from 2-100 wt % and is higher than the amount of the free fatty acid in the raw fat-oil. The present process can increase the fatty acid ester yield and purity of raw oil-fats having a low reaction activity, and has a high adaptability to raw materials.