Characteristics and stability of biofuels used as drop-in replacement for NATO marine diesel

Catalytic hydrothermal conversion diesel (CHCD-76), synthesized isoparaffin (SIP-76), and hydroprocessed renewable diesel (HRD-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 DSH-76, CHCD-76, and their blends with F-76. Chemical composition and physicochemical properties of these two biofuels, including viscosity, density, peroxide value, heat of combustion, acid number, and phase behavior, were determined using required ASTM methods. ASTM D4625 and D5304 methods were employed to investigate the long-term storage stability of these two biofuels and theirs blends with F-76. ASTM D5304 method was also modified to investigate the oxidation process of these fuel samples. In addition, ASTM D2274 tests were conducted to investigate oxidation stability of the neat and blended fuel samples. The influence of long-term storage and oxidation on fuel physicochemical properties was investigated based on ASTM methods. SIP-76 and CHCD-76 were found have superior storage and oxidation stability in comparison with petroleum F-76. This is also the first report on storage and oxidation stability of SIP-76 and CHCD-76.