Catalytic Conversion of Algae in Methanol and Ethanol to Biodiesel

This study demonstrated a one-step direct liquefaction and conversion of algae to biodiesel in methanol and ethanol with the catalysis of HZSM-5 (Si/2Al=50, 38, 25) and Y (HY(Si/2Al=10), NaY(Si/2Al=10) and USY(Si/2Al=12)) zeolites at a temperature range of 250 to 300 ^oC for 1 h. In the condition of no catalyst, bio-oil yield decreased with the increasing temperature. From 250-300 ^oC, the bio-oil decreased from 90%- 63% in methanol while the bio-oil decreased from 83% to 72% in ethanol. Gel permeation chromatography (GPC) results showed that weight-average molecular weight of bio-oil obtained in ethanol was a lot higher than that obtained in methanol. The weight-average molecular weight of bio-oil obtained in ethanol ranged from 2498 to 1977 and that obtained in methanol ranged from1571 to 1364 with temperature decreasing from 300 to 250 ^oC. TG/DTG results of the reaction solid residue gave an insight of the solid residue composition. TG/DTG showed that the residue composition obtained in methanol had a smaller molecular weight than that obtained in ethanol because the exothermic peaks showed at a relatively lower temperature using methanol than using ethanol. With the presence of the catalysts at 300 ^oC, bio-oil yield achieved in methanol was lower than that in ethanol. Wherevers, light bio-oil portion was higher in methanol than that in ethanol. The application of catalyst of both HZSM-5 and Y zeolites increased the light bio-oil content. Also higher acidity of the catalyst promoted higher light bio-oil content, the reason may be because that strong acidity promoted cracking reactions which converted large molecular compounds in the heavy oil to smaller compounds in the light oil.