Hydrocarbon Renewable and Synthetic Diesel Fuel Blendstocks: Composition and Properties

Abstract

We examined the chemical composition and properties of several diesel fuels and blendstocks derived from Fischer–Tropsch (FT) synthesis, hydroisomerization of lipids, and fermentation of sugar via the terpenoid metabolic pathway. Comprehensive two-dimensional gas chromatographic analysis with nonpolar and polar columns, 13C NMR, GC-MS, and elemental analysis were used to assess fuel chemistry. Performance properties included density, heat of combustion, cetane number, and cloud point, as well as other properties. The fuels consisted almost entirely of normal and iso-paraffins. Three samples contained residual oxygen below 0.1 mass %. All of the renewable and synthetic diesel fuels have significantly lower density than is typical for a petroleum-derived diesel fuel. As a result, they have slightly higher net heat of combustion on a mass basis (2%–3% higher), but lower heat of combustion on a volume basis (3%–7% lower). Two critical diesel performance properties, cetane number and cloud point, were correlated with iso-paraffin content and chain length. The results confirm that properties of hydroisomerized fats and oils, as well as FT diesel, can be tuned by increasing the degree of isomerization to lower cloud point which also lowers the cetane number. In spite of this trade-off between cloud point, and cetane number, the cetane numbers were still over 70 for fuels with cloud points as low as −27 °C. The terpenoid biofuel exhibited a cloud point below −70 °C and a cetane number of 58.

Green Diesel: Biomass Feedstocks, Production Technologies, Catalytic Research, Fuel Properties and Performance in Compression Ignition Internal Combustion Engines

“…Smagala et al [217] examined the effect of the isomerization on the CN number and the cloud point and shown that an initial mixture of normal saturation hydrocarbons with a CN rating of about 118 and a cloud point of 20 • C can be converted into a practical green diesel fuel of a cloud point down to −30 • C while keeping the CN number above 70. Another property which indicates the low temperature operability of the diesel fuel is the Cold Filter Plugging Point (CFPP).…”

Effects of hydrotreated vegetable oil on emissions of aerosols and gases from light-duty and medium-duty older technology engines

“…[6] Until recently, the U.S. underground mining industry has been almost exclusively using biodiesel fuels made from various vegetable oils and animal fats through the process of transesterification. [7] Those fuels are made of long-chain, fatty-acid methyl esters (FAME). FAME biodiesels are oxygenated fuels with approximately 11% oxygen content.…”

“…[27] HVORD is almost exclusively made of paraffinic and iso-paraffinic hydrocarbons and is virtually free of aromatic hydrocarbons, metals, sulfur, nitrogen, and oxygen-containing compounds. [7,26,27] When compared with ULSD, HVORD fuels have a lower density, a higher cetane number, higher net heat of combustion on a mass basis, and lower net heat of combustion on a volume basis. [26] …”

Effects of FAME biodiesel and HVORD on emissions from an older-technology diesel engine

“…FAME biodiesels contain on average between 10 and 11 percent oxygen. HVORD fuels are made from vegetable and algae oils and animal fats through hydrogenation and isomerization processes (Huber, O’Connor and Corma, 2007; Aatola et al, 2008; Smagala et al, 2013). By chemical composition, HVORD consists of mixtures of paraffinic and isoparaffinic hydrocarbons and is virtually free of aromatic hydrocarbons, metals, sulfur, nitrogen and oxygen-containing compounds.…”

“…Due to technical issues with high-pressure injection systems in the new-technology diesel engines, the majority of engine manufacturers only support the use of blends with low FAME-biodiesel content. The main restriction of HVORD was found to be compatibility with some materials (Smagala et al, 2013), lubricity and cold flow properties (Lapuerta et al, 2011). …”