Warm CO_2 Capture by MgO-Based Double Salts: Facilitation by Molten Alkali Nitrate Salts

摘要

The objective of this work is to develop warm temperature absorbents (300-470°C) for regenerable CO_2 capture and release from pre-combustion gas streams. By avoiding the cooling and re-heating of the syngas, which is necessary using currently available liquid CO_2 sorbents, a more efficient conversion process is possible. Capture of CO_2 at warm temperatures with any reasonable capacity cannot be accomplished through physisorption; stronger bonding of CO_2 is required. This suggests an approach through the reversible formation and decomposition of metal carbonates. From a thermodynamic perspective, MgO is an attractive material for capture and release of CO_2 (via magnesium carbonate formation) under warm temperature conditions. However, development of a practical, regenerable MgO absorbent has proven difficult. It appears that kinetics, rather than thermodynamics, are the limiting factor in conversion of MgO [1].