Preparation And Properties Of Pour-point Depressants Of Biodiesel

Biodiesel is de?ned as the monoalkyl esters of long chain fatty acids derived from renewable feed stocks like vegetable oils or animal fats which is the environmental fuels. But compared with mineral diesel,the solidifying point and viscosity of the biodiesel are moe higher resulting in poor low temperature properties. Thus the low temperature fluidity must be improved in order to be used widely.The pour point depressants of biodiesel containg polyacrylate and polymethacrylate were synthesised by two-step synthesis according to the principle that was the number of carbon atoms in the alkyl side chain of the pour point depressant was equal or similar to the biodiesel. The intermediates were synthesized firstly with the raw materials of acrylic acid,methacrylic acid,methyl acrylate and senior long-chain alcohol and with the catalyst of P-Toluene sulfonic acid and with the polymerization inhibitor of p-dihydroxybenzene. After that the pour point depressants were prepared with the materials of polyacrylic ester,methyl polyacrylic ester,vinyl acetate,maleic anhydride or maleic anhydride. Besides the effect of the pour point depressants on the low temperature of the biodiesel were researched.In preparing of polyacrylate the influences that the length of carbon chain acrylate, polymerization temperature,ratio of raw materials and added content to the function of the product were investigated. The product was measured by means of FTIR spectra. The results showed that the proper conditions were the molar ratio of acrylic,maleic anhydride,vinyl was 4:1:4,the reaction temperature was 85~90℃,reaction time was 6h,the dosage of toluene was 20 m L and the dosage of benzoyl peroxide was 5 g per mole acrylate. The decline of condensation point increased firstly and then droped down with the increasing of dosage of maleic anhydride and temperature,but the dosage of the vinyl acetate could not affect the coagulation effects.In preparing of polymethacrylate the influences that the kinds of the raw materials, temperature,dosage of raw materials etc. were also investigated. The results showed that the metacrylic acid ester was first synthesised with the conditions as follows: methacrylic acid: long-chain alkyl ratio was 1.2:1,the dosage of P-Toluene sulfonic acid and polymerization inhibitor of p-dihydroxybenzene were 1.0w% and 0.9 wt% respectively,reaction time was 5h and reaction temperature was 110~120℃. And then the product was prepared with the conditions as follows: reaction temperature was 85~90℃,polymerization reaction time was 5h and the mole ratio of maleic anhydride: vinyl acetate: 18 methacrylate ester was 1:4:4. When the two kinds of the pour point depressants of biodiesel were added into the biodiesels prepared from different raw materials with dosage of 1%,the solidifying point and cold filter plugging point of biodiesel can be reduced 4~9℃ and 2~6℃ which showed that the products could improve the low temperature fluidity of biodiesel containing unsaturated fattyacid or saturated fatty acid.