Analysis of CO2 Sorption/Desorption Kinetic Behaviors and Reaction Mechanisms with Steam on Li4SiO4

摘要

The greenhouse effect and energy crisis are currently two of the most important problems worldwide. Hence, CO2 capture technologies are required to decrease CO2 emissions to the atmosphere and improve energy efficiency. They can be used in the direct separation of CO2 from the high-temperature exhaust gases from power plants, particularly in in situ CO2 sorption enhanced fuel steam reforming processes, which aims to produce pure hydrogen at lower temperature. The key point of a CO2 sorption enhanced reaction system is to develop a satisfactory solid CO2 captor with a large capacity, high selectivity, good cycle performance, and proper kinetic behaviors at relatively high temperatures. Thus far, several materials, such as hydrotalcite-like materials, CaO-based sorbents, and lithium-containing materials, have been proposed for CO2 capture1-4 . Among these materials, lithium orthosilicate (Li4SiO4) is considered to be one of the most potential materials. Li4SiO4 has been reported to adsorb CO2 more than 30 times faster than Li2ZrO3 and is lighter and cheaper than Li2ZrO3. The mass uptake on Li4SiO4 due to CO2 adsorption is almost 50% greater than the weight change for Li2ZrO3. It has also been used in sorption enhanced fuel steam reforming experiments, where it has shown an evidently promoting effect on the process.