Comprehensive analysis of the physicochemical properties of butylal and butylal blends as a potential diesel fuel

• Important fuel properties reported for different base fuels and blending rates. • The ignition behaviour of butylal and butylal blends was investigated in detail. • Blend walls were identified for standard fuels and a renewable fuel. • Additives for oxidation stability and lubricity were tested. Among the renewable alternatives for fossil diesel fuel (DF) that are currently considered, Poly(oxymethylene) ethers are promising candidates due to their good ignition behaviour and soot-reducing properties. In this study, fuel-related properties of butylal (poly(oxymethylene) dibutyl ether or OMBE 1 ) and blends of butylal with fossil diesel fuel of European and American quality and, for the first time, paraffinic DF from hydrotreated vegetable oil (HVO) are measured and investigated to evaluate possible blending rates. The researched fuel properties are indicated cetane number, oxidation stability, lubricity, flash point, calorific value and water content. Novel data on the ignition behaviour and viscosity and density at low temperatures is presented. Furthermore, the effect of a lubricity and an oxidation stability improver on butylal was tested to improve fuel properties. Pure butylal does not fulfil the requirements of the fuel standards EN 590, ASTM D945a, EN 15940, and DIN TS 51699, which implies that it is not compatible with the existing engine technology. Blending butylal improves the cetane number of the fossil diesel fuels but not the already good cetane number of HVO. Disadvantageous fuel properties are a low calorific value and the hygroscopic properties of butylal. The poor lubricating properties and the oxidation stability can be improved with the additives tested. The results show that butylal can be promising to be used as a low climate intensity blend component to diesel fuels with mass fractions of up to 0.3 g/g, depending on the base fuel.