Study on the Effect of Silica Sand Method in Improving the Color of Non-Conforming Mixed Oil Distilled Diesel

An in-depth analysis and experimental study were conducted to address the abnormal coloration of diesel in the Southern China finished oil pipeline network. This network spans multiple provinces and primarily transports 92# gasoline, 95# gasoline, and 0# diesel. Due to the direct contact between different oil products and their physicochemical property differences—particularly during gasoline-diesel mixing—the use of distillation for mixed oil treatment was found to exacerbate abnormal diesel coloration, especially at end-station processing points. Gas chromatography analysis revealed that the discoloration is primarily caused by excessive asphaltene and resin content. Two mitigation approaches were tested: (1) adjusting production parameters and (2) applying decolorizing agents to reduce the color of distilled diesel. Adjusting production parameters did not yield significant improvement. For the decolorizing method, a comparative evaluation of activated carbon, clay, and silica gel sand demonstrated that silica gel sand achieved the best performance in terms of decolorization efficiency, practical dosage, and environmental safety. Further investigation into the impact of silica gel sand particle size on diesel coloration identified the optimal dosage and operating conditions for medium-grain silica gel sand. Comprehensive analysis confirms that silica gel sand decolorization significantly reduces diesel coloration while offering economic and environmental advantages, establishing it as the recommended decolorizing agent for this application.