Asphaltenes Aqueous Conversion to Humic and Fulvic Analogs via Oxy-Cracking

Abstract

Asphaltenes surplus production in northern Alberta facilities as a result of heavy oil upgrading incentivizes searching for alternative processes to coking or gasification, with less environmental footprint and/or lower costs. Oxy-cracking of asphaltenes in liquid phase under alkali conditions could be a new approach to creating higher value products. In the present study, asphaltene particles/drops were solubilized in water with the ultimate intention of reducing their molecular weight, converting them to analogs of humic substances with potential applications as soil cofertilizers or other industrial applications. For evaluating the feasibility of solubilizing asphaltene particles by oxy-cracking, experiments were done in a batch reactor to study the parameters maximizing the solubilization toward liquid products: temperature, residence time, pressure, base effect, asphaltenes mass, and stirring speed. The results showed that temperature and residence time are the two parameters affecting reaction the most, being the optimum values 180–210 °C and 1–2 h, respectively. The intermediate product of asphaltenes oxy-cracking reaction is water-soluble asphaltenes (WSA), and the final product is CO 2 . The water solubilized products were found to contain organic carboxylic, carbonyl, phenolic, and sulfonic functions, responsible for their dissolution in water. At less severe conditions, WSA had characteristics similar to humic analogs; but with increasing reaction severity, products aromaticity increased and lower molecular weight components (fulvic analogs) were formed.