To reduce the tendency of biodiesel to crystallize at low temperatures, branched-chain alcohols were used to esterify various fats and oils, and the crystallization properties of the branched esters were compared with those of methyl esters by using differential scanning calorimetry (DSC), cloud point, and pour point. Compared with the methyl esters that are commonly used in biodiesel, branched-chain esters greatly reduced the crystallization onset temperature (Tco) of neat esters and their corresponding ester diesel fuel blends. Isopropyl and 2butyl esters of normal (-10 wt% palmitate) soybean oil (SBO) crystallized 7-1 1 and 12 14°C lower, respectively, than the corresponding methyl esters. The benefit of the branched-chain esters in lowering Tco increased when the esters were blended with diesel fuel. Esters made from a Iow-palmitate (3.8%) SBO crystallized 5-6°C lower than those of normal SBO. Isopropyl esters of lard and tallow had Tco values similar to that of methyl esters of SBO. DSC provided an accurate means of monitoring crystallization, and the DSC results correlated with cloud and pour point measurements.JAOCS 72, 1155 1160 (1995).Refining. The lard was refined by adding 25.6 g of 12 Baum6 (8.0 wt%) NaOH solution to 350 g lard, agitating the mixture with a magnetic stirrer at high speed for 20 min at 40°C and then at low speed for 60 min at 70°C, and followed by filtering (Whatman No. 4 filter paper) in an oven at 65°C.

Analysis of MCPD esters and glycidyl esters in vegetable oils using the indirect method proposed by the DGF gave inconsistent results when salting out conditions were varied. Subsequent investigation showed that the method was destroying and reforming MCPD during the analysis. An LC time of flight MS method was developed for direct analysis of both MCPD esters and glycidyl esters in vegetable oils. The results of the LC–TOFMS method were compared with the DGF method. The DGF method consistently gave results that were greater than the LC–TOFMS method. The levels of MCPD esters and glycidyl esters found in a variety of vegetable oils are reported. MCPD monoesters were not found in any oil samples. MCPD diesters were found only in samples containing palm oil, and were not present in all palm oil samples. Glycidyl esters were found in a wide variety of oils. Some processing conditions that influence the concentration of MCPD esters and glycidyl esters are discussed.

The effects of using blends of methyl and isopropyl esters of soybean oil with No. 2 diesel fuel were studied at several steady‐state operating conditions in a four‐cylinder turbocharged diesel engine. Fuel blends that contained 20, 50, and 70% methyl soyate and 20 and 50% isopropyl soyate were tested. Fuel properties, such as cetane number, also were investigated. Both methyl and isopropyl esters provided significant reductions in particulate emissions compared with No. 2 diesel fuel. A blend of 50% methyl ester and 50% No. 2 diesel fuel provided a reduction of 37% in the carbon portion of the particulates and 25% in the total particulates. The 50% blend of isopropyl ester and 50% No. 2 diesel fuel gave a 55% reduction in carbon and a 28% reduction in total particulate emissions. Emissions of carbon monoxide and unburned hydrocarbons also were reduced significantly. Oxides of nitrogen increased by 12%.

Methyl soyate, made from typical soybean varieties, has a crystallization onset temperature (Tco) of 3.7~ and, as a biodiesel fuel, is prone to crystallization of its high-melting saturated methyl esters at cold operating temperatures. Removal of saturated esters by winterization was assessed as a means of reducing the Tco of methyl soyate. Winterizing neat methyl esters of typical soybean oil produced a /-co of-7.1 ~ but this was not an efficient way of removing saturated methyl esters because of the low yield (26%) of the separated liquid fraction. However, a Tco of -6.5~ with 86% yield was obtained by winterizing the neat methyl esters of a Iow-palmitate soybean oil; a Tco of -5.8~ with 77% yield was obtained by winterizing methyl esters of normal soybean oil diluted with hexane.JAOCS 73, 631-636 (1996).

The objective of this study was to determine the effect of various amounts of unsaponifiables and bound glycerol on the crystallization temperatures of methyl soyate used as biodiesel. The preparation of methyl esters did not affect the amount of unsaponifiable matter in biodiesel. A synthetic unsaponifiable mixture added to distilled methyl soyate and blends of methyl soyate and No. 1 diesel fuel (20:80, vol/vol) did not affect the crystallization onset temperature, cloud point, or pour point at concentrations up to 3% by weight. The amounts of monoglycerides and diglycerides in methyl soyate decreased from 2.60 and 9.87%, respectively, to 0% as the methanol/soybean oil ratio increased from 90 to 200% of the theoretical requirement. Transesterification reactions conducted with less than 130% of the theoretical amount of methanol resulted in methyl soyate with a higher cloud point because of the presence of saturated mono-and diglycerides. Pure mono-and diglycerides added to distilled methyl soyate at 0 to 1.0% did not change the pour point of the esters, but the cloud point of esters increased with increasing amount of saturated mono-or diglyceride. Pure saturated mono-or diglyceride presented in concentrations as low as 0.1% increased the cloud point of methyl soyate. Similar results were obtained with mono-and diglyceride mixtures present in incompletely converted methyl soyate.