(467c) Production of Highly Concentrated Stream of Hydrogen from Syngas in Igcc Processes

Advanced power generation technologies such as Integrated Gasification-Combined Cycle (IGCC) processes are among the leading contenders for power generation conversion in the 21st century because of their significantly higher efficiencies and potential environmental advantages compared to pulverized coal combustion (PC) processes. It has been projected that IGCC power plants will exceed 50% energy efficiency (compared to 35% in PC) within a decade. This increase in efficiency will reduce the emissions of CO2 per unit of power generated by 30%. Further reduction in CO2 emissions can be achieved by separation of CO2 from the coal gas for capture and sequestration. In IGCC processes equipped with high temperature particulate removal and hot or warm temperature sulfur removal subsystems, to avoid efficiency losses, it is desirable to remove CO2 in the temperature range of 300°-500°C, which makes regenerable MgO-based sorbents ideal for such operations. Furthermore, CO2 removal results in shifting the water-gas-shift (WGS) reaction toward significant reduction in carbon monoxide (CO) concentration, generating additional hydrogen in the process, which is considered as the higher value product as transportation fuel, or used as feed stream for fuel cell application or production of other premium chemicals. However, highly durable, reactive, and attrition resistant sorbents are required for such application.

This paper presents the results obtained with a highly reactive and attrition resistant regenerable MgO-based sorbent which can simultaneously remove carbon dioxide and significantly enhance hydrogen production in a single reactor. The results of the experimental tests performed with the sorbent in a High-Pressure ThermoGravimetric Analyzer (HPTGA) unit showed high reactivity and reasonable capacity for CO2 absorption in the temperature range of 300° to 500°C at 20 bar, which was also confirmed in tests carried out in a. high-pressure packed bed reactor with CO2/N2/H2O mixture. Additional tests have been carried out with simulated syngas mixtures to determine the catalytic activity of the sorbent in WGS reaction in the temperature range of 300° to 450°C.