Understanding the morphology of supported Na2CO3/γ-AlOOH solid sorbent and its CO2 sorption performance

Sodium carbonate (Na2CO3)-based sorbent is promising for CO2 capture from humid flue gas due to the abundant/extensive distribution of raw materials and low cost to retrofit the extant power plants. However, the lack of knowledge about the relationship between Na2CO3 and supports inhibits the efficiency of sorbent development. In this paper, a series of boehmite supported Na2CO3-based solid sorbents (Na2CO3/gamma-AlOOH) have been fabricated via incipient wetness impregnation technique and various characterizations have been carried out to understand the morphological changes of these sorbents arising from support effects. First, Na2CO3 bond ionically on gamma-AlOOH surface sites in amorphous form when the loading is below 17 wt% and then Na2CO3 crystallites grow uniformly with the increase of loading amount. The size of Na2CO3 crystallites on gamma-AlOOH decreases by 26.2% and more high-index facets, such as (1 1 2) and (-4 0 2) facets, are exposed comparing with unmodified Na2CO3. Moreover, nanostructured Na2CO3 prefers to attach the inner surface of.-AlOOH, reserving numerous hydroxyl groups on the external surface of the support even at high loadings. CO2 sorption performance of the selected sorbent, NaAlH29, has been investigated under different operation conditions as well and the maximum CO2 sorption capacity, 2.25 mmol/g, is reported. In addition, a 43-cycle CO2 sorption/desorption test indicates that the developed NaAlH29 sorbent, with good stability, is a potential option for post-combustion CO2 reduction in industry.