Comparison of Fuel Filters and Adsorption Filters for Metal Carboxylate Separation

Heavy-duty transportation accounts for significant part of the greenhouse gas emissions. Currently the most common powertrain for long-haul trucks is compression-ignited engines. In order to reduce the greenhouse gas emissions of these engines, renewable fuels, such as biodiesel can be used. Today biodiesel is used as a drop-in fuel, however when biodiesel is mixed with conventional diesel, soft particles may form. Soft particles have been identified as a mixture of insoluble impurities and degradation products in the fuel. These soft particles can lead to deposits in the injection and fuel filtration system, leading to reduced engine performance. In this paper, zinc-neodecanoate and soft particles from the degradation of biodiesel is studied. In both cases, the emphasis is on soap type contaminants. Zinc-neodecanoate has shown to lead to nozzle fouling, while soft particles from degradation of biodiesel have been found in diesel fuel filters. This study examines four different type of fuel filters to estimate separation efficiency of zinc-neodecanoate in current vehicles. In addition, adsorption filtration is examined to see its potential for vehicle application. The separation efficiency of the adsorption filter is compared to currently used filter sheets. The filtration has been conducted on a custom-built filter rig, while the efficiency of filtration is examined by the use of gas chromatography-mass spectrometry and inductively coupled plasma atomic emission spectroscopy. Adsorption filters showed a good potential for the removal of soap type soft particles. The data collected in this study show promising results for adsorption filters. The results indicate the necessity of continued testing in a full-scale fuel system to further investigate the applicability of adsorption filters.