Characteristics and Stability of Second Generation Biofuels Used As Drop-in Replacement for Marine Diesel

Hydroprocessed renewable diesel (HRD-76), catalytic hydrothermal conversion diesel (CHCD-76), and direct sugar to hydrocarbon (DSH-76) have been produced in sufficient quantity and supplied to the U.S. Navy for blending with traditional marine diesel NATO F-76. The present work investigates the storage and oxidation stabilities of HRD-76, CHCD-76, DSH-76, and blends of these renewable diesels with F-76. Physical properties and chemical composition of these three biofuels, including viscosity, density, peroxide value, heat of combustion, acid number, and phase behavior, were measured. The long-term storage stability of these biofuels and theirs blends with F-76 was studied based on ASTM methods D4625 and D5304. ASTM D2274 tests were also conducted to investigate oxidation stability of the neat and blended fuel samples. An extended ASTM D2274 method was employed to investigate the influence of oxidation time on stability. The influence of long-term storage on physicochemical properties and phase behavior was investigated using ASTM methods.