Lubricity-Enhancing Low-Temperature Diesel Fuel Additives

Branched chain alkyl esters have lower crystallization temperatures than those with straight chain headgroups. We investigated the effect of branched chain headgroups on the cold flow properties and lubricity of alkyl esters. Commercial grade canola methyl ester was transformed into branched chain alkyl esters through a two or three-stage base-catalyzed transesterification reaction with 1-methoxy-2-propanol and 3-methyl-1-butanol. Conversion rates between 85 and 95% were achieved. The alkyl esters exhibited improved cold flow properties. The pour points were reduced from -12 to -27 degrees C as a result of incorporating branched headgroups. Addition of 0.1 or 0.2% (v/v) 1-methoxy-2-propyl alkyl ester improved the lubricity of a commercial pre-production ultra low sulfur diesel (ULSD) fuel, as determined by increased lubricity number and reduced wear scar diameter. The inclusion of methyl-tert butyl ether or ethanolamides additives to ULSD containing alkyl esters had an antagonistic effect on lubricity. The branched-chain alkyl esters have the potential to be used as lubricity-enhancing and low-temperature fuel additives.