TY - JOUR
T1 - Fuel Properties of Oxymethylene Ethers with Terminating Groups from Methyl to Butyl
AU - Lucas, Stephen
AU - Liang Chan, Fan
AU - Fioroni, Gina
AU - Foust, Thomas
AU - Gilbert, Alayna
AU - Luecke, Jon
AU - McEnally, Charles
AU - Serdoncillo, Justine
AU - Zdanowicz, Andrew
AU - Zhu, Junqing
AU - Windom, Bret
N1 - Publisher Copyright:
© 2022 American Chemical Society.
PY - 2022
Y1 - 2022
N2 - Oxymethylene ethers (OMEs) have been studied as possible additives or replacements for diesel fuels. Typically, studies have considered only methyl-terminated OMEs. Recent structure-property relationship models suggest that extended-alkyl OMEs may provide improvements to many of the properties of methyl-terminated OMEs that make them less suitable as diesel fuel blendstocks. In this work, we describe the synthesis and characterization of 16 different OMEs with methyl-, ethyl-, propyl-, butyl-, isopropyl-, and isobutyl-terminating alkyl groups with varying oxymethylene chain lengths. Indicated cetane number, lower heating value, flash point, density, viscosity, vapor pressure, and oxidative stability are tested via ASTM standard methods. Additionally, water solubility, boiling point, seal material compatibility, and sooting propensity (via the yield sooting index) are measured for these fuels. For diesel compatibility, all tested OMEs except smaller methyl and ethyl OMEs and the branched isopropyl OME meet cetane number requirements. Extending the alkyl end group increases the heating value, but all OMEs, due to their oxygen content, have heating values less than diesel. Despite this, all OMEs show significant reductions in soot production per unit heating value. Only the heaviest OMEs meet diesel viscosity requirements, and most are higher density than diesel. OMEs with larger alkyl groups show the highest stability under accelerated auto-oxidation conditions. Increases in alkyl group length cause order of magnitude reduction in water solubility, from hundreds of g/L for methyl terminated OMEs to hundreds of mg/L for butyl terminated OMEs. Limited seal material testing indicates that PEEK polymers are unaffected by OMEs, and while extended alkyl groups may improve compatibility with FKM (Viton), other common elastomers (NBR, silicone) remain incompatible with all tested OMEs. Overall, it is found that methyl-terminated OMEs exhibit the most potential for soot reduction, but OMEs with larger propyl- and butyl-terminating alkyl groups show improved compatibility with existing diesel systems.
AB - Oxymethylene ethers (OMEs) have been studied as possible additives or replacements for diesel fuels. Typically, studies have considered only methyl-terminated OMEs. Recent structure-property relationship models suggest that extended-alkyl OMEs may provide improvements to many of the properties of methyl-terminated OMEs that make them less suitable as diesel fuel blendstocks. In this work, we describe the synthesis and characterization of 16 different OMEs with methyl-, ethyl-, propyl-, butyl-, isopropyl-, and isobutyl-terminating alkyl groups with varying oxymethylene chain lengths. Indicated cetane number, lower heating value, flash point, density, viscosity, vapor pressure, and oxidative stability are tested via ASTM standard methods. Additionally, water solubility, boiling point, seal material compatibility, and sooting propensity (via the yield sooting index) are measured for these fuels. For diesel compatibility, all tested OMEs except smaller methyl and ethyl OMEs and the branched isopropyl OME meet cetane number requirements. Extending the alkyl end group increases the heating value, but all OMEs, due to their oxygen content, have heating values less than diesel. Despite this, all OMEs show significant reductions in soot production per unit heating value. Only the heaviest OMEs meet diesel viscosity requirements, and most are higher density than diesel. OMEs with larger alkyl groups show the highest stability under accelerated auto-oxidation conditions. Increases in alkyl group length cause order of magnitude reduction in water solubility, from hundreds of g/L for methyl terminated OMEs to hundreds of mg/L for butyl terminated OMEs. Limited seal material testing indicates that PEEK polymers are unaffected by OMEs, and while extended alkyl groups may improve compatibility with FKM (Viton), other common elastomers (NBR, silicone) remain incompatible with all tested OMEs. Overall, it is found that methyl-terminated OMEs exhibit the most potential for soot reduction, but OMEs with larger propyl- and butyl-terminating alkyl groups show improved compatibility with existing diesel systems.
KW - alkyl groups
KW - diesel fuel blendstocks
KW - methyl-terminated OME
KW - OME
KW - oxymethylene ethers
KW - soot reduction
UR - http://www.scopus.com/inward/record.url?scp=85136613964&partnerID=8YFLogxK
U2 - 10.1021/acs.energyfuels.2c01414
DO - 10.1021/acs.energyfuels.2c01414
M3 - Article
AN - SCOPUS:85136613964
SN - 0887-0624
VL - 36
SP - 10213
EP - 10225
JO - Energy and Fuels
JF - Energy and Fuels
IS - 17
ER -