Design and Synthesis of Temperature Switchable Non-ionic Block Copolymers for Application to Oil Sands Extraction

Abstract

Based on the analysis of typical warm water oil sands extraction process, we investigated the use of a novel temperature switchable non-ionic block copolymer, poly (ethylene glycol)-b-poly (N-isopropyl acrylamide) (MPEG-b-PNIPAM), to enhance the bitumen recovery and the recycle of the polymer after the extraction through the temperature change in the extraction process. The temperature switchable polymer was designed to lower the interfacial tension between bitumen and water at high temperature for enhancing the bitumen liberation. When the temperature goes down, the copolymer can be recovered with process water for reuse in liberation and extraction. Two temperature switchable non-ionic block copolymers, MPEG2000-b-PNIPAM50 and MPEG750-b-PNIPAM35, were synthesized and characterized by IR spectroscopy and 1HNMR to elucidate the chemical structure of the two copolymers. The polymers synthesized showed good interfacial activity with temperature switchable properties. Investigations using a home-built on-line bitumen liberation analyzer showed that the synthesized polymer enhanced bitumen liberation process. The Denver flotation cell extraction tests showed an enhanced bitumen recovery by the addition of the synthesized polymers. A home-built induction timer was used to evaluate the induction time between air bubble and bitumen surfaces. The results showed that the polymer with short chain length helped reduce the induction time and could help aeration while the polymer with longer chain made aeration less favorable. By using toluene as the oil phase, we demonstrated a good recoverability of the polymer when temperature reduced to 25 ℃. It is proved that the polymer can be reused in liberation and extraction to reduce the operating cost of the process.