Thermal and catalytic pyrolysis of date palm stones: Production, characterization of pyrolytic oil and study of performance and emission characteristics in CI engine

The main purpose of this study is to investigate the opportunity of using date palm stones (DPS) pyrolytic oil as a renewable fuel in internal combustion engines. Thermal and catalytic pyrolysis of DPS was carried out in a fixed bed reactor for the production of DPS pyrolytic oil. Pyrolysis experiments were performed at a temperature of 500°C, with 10°C/min as heating rate and Al2O3 as catalyst (used with 20% by weight). Al2O3 catalyst achieved a higher bio-oil yield of 38.41 wt.%. Moreover, the addition of a catalyst enhanced the generation of energetic gases CH4 (21.20%) and H2 (15.57%). These significant proportions give the syngas good fuel proprieties. Catalytic pyrolysis of DPS produced a biofuel with lower density, lower viscosity, and higher energy content. The higher heating value of this biofuel was found to be 33.70 MJ/kg. Biofuels from catalytic (BF2) and noncatalytic (BF1) pyrolysis of DPS were mixed with diesel fuel in a volume percentage of 20%. The biofuels blends were tested in a diesel engine at variable loads and a constant engine speed of 1500 rpm to evaluate the performance and emission characteristics analysis. Despite their low proprieties compared to diesel, the brake thermal efficiencies (BTEs) for both biofuels blends were close to those for diesel fuel at all tested loads. On the other hand, brake specific fuel consumption (BSFC) was found relatively higher for both blends compared to diesel. Using BF2-B showed lower levels of NOx and soot emissions and higher maximum thermal efficiency (29.15%) compared to BF1-B operation. As a result, the addition of Al2O3 catalyst improved the performance and emissions characteristics of diesel engine. This investigation reveals that DPS pyrolytic oil could be alternative fuels in diesel engines.