Composition and fuel properties of pyrolysis products of industrial wastewater sludge from the Karachaganak oil and gas condensate field

Abstract

This study comprehensively examines the chemical composition, fractional separation, and fuel properties of liquid products derived from the thermal treatment of organomineral sludge. The focus is on characterizing the liquid phase, including its hydrocarbon composition and fractional distribution, and evaluating its potential as a fuel. Gas chromatography, elemental analysis, and standard distillation methods were employed. The resulting liquid product was found to be rich in hydrocarbons, specifically isoparaffins (32,8%), aromatics (25,6%), and naphthenes (23,4%), with smaller amounts of olefins (8,5%) and oxygen-containing compounds (4,5%). Distillation analysis revealed a wide boiling range (73-370 °C), with approximately 70% of the product boiling below 200 °C, indicating a significant gasoline-range fraction. The light fraction (up to 100 °C) contained toluene (10,96%), ethylbenzene (3,06%), o-xylene (3,75%), trimethylbenzene (4,19%), and C₇–C₁₇ isoparaffins. Calculations estimate a high octane number for the light fraction: 93,3 by the research octane number (ron) method and 76,8 by the motor octane number (mon) method, primarily attributed to the contributions of isoparaffins (38,1 units) and aromatics (33,5 units). Octane number estimation of different fractions revealed that the 70-100 °C fraction has the highest octane potential (approximately 95-98 ron). However, the presence of olefins may reduce product stability. To meet standard motor fuel specifications, further purification, such as hydrotreatment to reduce olefin content, may be necessary. These results suggest that liquid products from thermally treated organomineral waste hold promise as a feedstock for high-octane fuel components and provide a foundation for developing resource-efficient processing technologies.