Physical solvents and process intensification for carbon capture and gas sweetening

Abstract

Efficient and economic carbon capture technologies are being globally investigated due to the high and increasing carbon emissions in the atmosphere. The current available Carbon Capture and Sequestration (CCS) technologies present limitations that make their implementation economically unattractive to most combustion-powered industries. Physical solvents are more attractive than chemical solvents primarily due to their significantly more economic regeneration energy requirements. The application of ionic liquids as physical solvents such as the one studied in this work, 1-butyl-3- methylimidazolium tricyanomethanide ([bmim][tcm]), is advantageous because of its negligible vapor pressure, high thermal and chemical stability, lower regeneration requirements, high carbon dioxide solubility, and relatively low price compared to other ionic liquids. In addition, literature reports that [bmim][tcm] exhibits a phenomenon of enhanced CO2 solubility in the presence of water, which together with improved physical properties such as lower viscosity, makes these ionic liquid and water mixtures promising solvents for carbon capture. Rotating foam reactors serve as a process intensification technology providing mass-transfer coefficients orders of magnitude greater than conventional absorption towers. The combination of the promising [bmim][tcm] in water as carbon capture physical solvents and the application of the rotating foam reactor for process intensification for gas sweetening and CCS processes was studied in this work. Experimental CO2 solubility results for [bmim][tcm] showed decreasing solubility with increasing water content making the ionic liquid and its mixtures with water less attractive. [bmim][tcm] and its mixtures with water are not competitive enough with the conventional amine-based solvents. The rotating foam reactor showed high KL? values reaching a maximum of 0.19 s-1. Therefore, process intensification and the horizontal foam reactor in particular continues to prove to be promising for more efficient CO2 capture processes.

Date of Award	2015
Original language	American English
Supervisor	Cornelis Peters (Supervisor)