Date of Award

January 2013

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Chemical Engineering

First Advisor

Brian M. Tande

Abstract

The most dominant CO2 capture technology used for pre-combustion capture involves the application of physical solvents. Despite the low energy required to regenerate physical solvents and their high capacity for capturing and separating acid gases from the syngas produced in a gasification plant, physical solvents have some disadvantages including CO2 pressure loss and the energy required to pump the solvent to the high pressure absorber.

The primary objective of this work is to evaluate the use of composite polymeric membranes for the recovery of CO2 from CO2-rich solvent streams. To achieve this purpose, an experimental bench-scale setup was built to investigate and quantify CO2 removal capacity from the rich solvent across different types of membranes.

Dimethyl ether of polyethylene glycol (Selexol) is used as the solvent since it is reputed to be one of the major physical solvents for CO2 removal. To evaluate the effectiveness of different types of membranes, the CO2 permeation rate and membrane selectivity were measured for different membranes.

The results of the screening study indicated that PDMS-based membranes (PERVATECH and PERVAP 4060) have higher CO2 permeability compared to PVOH-based membranes (PERVAP 1211 and PERVAP 1201). The best membrane for further analysis and experiments to find the optimum operational conditions was chosen as PEVAP 4060 from SULZER due to its high CO2 flux and selectivity compared to other membranes.

Following a two-factor two -level full factorial design with two replicates an three center points, a statistical analysis was also performed to identify the significant factors for each individual response such as permeation rate, leak rate and selectivity. For CO2 flux, pressure appeared to be strongly significant. However, solvent flow rate had no significant effect on the rate of CO2 permeation. With respect to the solvent leak, the analysis of Pareto charts suggested pressure to be significant and solvent flow rate to be insignificant. Neither system pressure nor solvent flow rate found to be significant considering the selectivity as the experiment's response. Finally, regarding the percent recovery, both the system pressure and solvent flow rate appeared to be significant.

In order to examine the chemical stability and structural integrity of the membranes after being exposed to the high pressure solvent, a series of post-experiment characteristic tests such as FTIR and DSC were performed. The results of these studies revealed no major changes.

Download

Share

COinS