(688f) Experimental Investigation of Sorbents for Warm CO2 Capture in IGCC System

Integrated gasification combined cycle with CO₂ capture (IGCC-CCS) is the next-generation coal power plant which achieves a higher energy efficiency and better emission control compared with the traditional pulverized coal plant. But the current CO₂ separation technology based on solvent absorption (e.g. Selexol, Rectisol) operates at a low temperature, which requires additional cooling and reheating units, leading to a significant energy loss and capital expenditure. To resolve this problem, warm CO₂ capture technology, which separates CO₂ at an elevated temperature, is proposed.

In this work, two potential warm CO₂ capture approaches – membrane and sorbent were first compared through process simulation. The process simulations indicate sorbent technology is more promising for the IGCC-CCS application. To develop an optimal sorbent material, the desired sorbent properties were first identified. Among them, the proper operating window and sorption behavior in the presence of water are the most important. Using these criteria, we screened available sorbent materials using computational chemistry, and identified two promising candidates: metal hydroxide and silica-supported amine. Detailed experimental work was then performed to investigate their performance as sorbents for warm CO₂ capture. To facilitate the experimental work, a lab-scale packed bed reactor and a high pressure balance were set up to measure adsorption isotherm, working capacity, kinetics and sorption behavior in the presence of water. Preliminary results indicate a water-enhanced sorption for both materials at very high temperature. Metal hydroxide shows large capacity at high temperature but suffers from the slow kinetics. Silica-supported amine has shown good kinetics and regenerability in the presence of water at mild temperatures, but the capacity at high temperature needs to be improved.  Some potential solutions to resolve these problems are presented. This presentation provides a framework of interrelating process simulation, thermodynamic calculation and experimental work to identify the optimal sorbent for warm CO₂ capture.