Experimental studies on production of deoxygenated vegetable oils and their performance evaluation in a compression ignition engine

The present experimental investigation aims at production of second-generation biofuels from straight vegetable oils (SVOs) and carrying out their performance assessment in a compression ignition (CI) engine. The intended second-generation biofuels, i.e., deoxygenated vegetable oils (DVOs), were produced through catalytic deoxygenation of palm and karanja SVOs over 5 wt% Pd/C catalyst under an inert (N₂) atmosphere using a batch autoclave reactor. Fuel characterization and elemental analysis were carried out for the produced DVOs to evaluate various fuel properties. In order to evaluate the fuel composition and presence of diesel range aliphatic hydrocarbons, GC-MS and FT-NMR tests were carried out. The engine performance and emission characteristics with the DVOs were evaluated in a developed experimental diesel engine setup. Results showed that the DVOs exhibit better engine performance, lower emissions, and marginally higher NO_x emissions compared to those with diesel fuel. In order to establish the DVOs as possible CI engine fuels, the performance and emission characteristics with the DVOs were compared against those with their corresponding established B20 biodiesel blends. The comparative assessment revealed that the engine performance and emission characteristics with the DVOs are superior compared to those with the corresponding B20 biodiesel blends. Especially, the NO_x emissions with the DVOs are significantly lower as compared to their corresponding B20 biodiesel blends.