화학공학소재연구정보센터
Fuel, Vol.246, 425-442, 2019
Oil-in-water emulsification of Athabasca bitumen with pyrrolidine solution
This paper presents an experimental study of use of pyrrolidine solutions to induce the oil-in-water (o/w) emulsion of Athabasca bitumen without using synthetic surfactants. Pyrrolidine, an organic alkali, acts not only as an alkali that generates natural surfactants from acidic oil components in bitumen, but also as a cosolvent that improves the fluidity of the o/w emulsions. Experimental results show that the o/w emulsions created by pyrrolidine solutions can result in a large mobility increase of bitumen because of their low viscosity and high bitumen content. O/w emulsions were observed at low pyrrolidine concentrations (below 20 wt% and as low as 0.5 wt%) and low salinities (0 and 1000 ppm). For example, the sample of 0.5 wt% pyrrolidine in 1000-ppm NaCl brine with 7: 3 water-oil-ratio showed a single-phase o/w emulsion at all experimental temperatures from 298 K to 373 K. In comparison to the original bitumen, the o/w emulsion was 4-6 orders of magnitude less viscous at 298 K, 2-3 orders of magnitude less viscous at 323 K, and 1-2 orders of magnitude less viscous at 353 K. The affinity of the organic alkali for asphaltic bitumen is important for o/w emulsification at a wide range of temperatures. Pyrrolidine is superior to the other organic alkalis tested, diethylamine and triethylenetetramine, likely because the cyclic structure makes pyrrolidine more compatible with the asphaltic bitumen. The favorable result with pyrrolidine is also confirmed by the Hansen solubility dispersion parameter.