High CO₂ Storage Capacity in Alkali‐Promoted Hydrotalcite‐Based Material: In Situ Detection of Reversible Formation of Magnesium Carbonate

Abstract

Alkali-promoted hydrotalcite-based materials showed very high CO(2) storage capacity, exceeding 15 mmol g(-1) when the carbonation reaction was carried out at relatively high temperature (300-500 °C) and high partial pressure of steam and CO(2). In situ XRD experiments have allowed correlation of high CO(2) capacity to the transformation of magnesium oxide centres into magnesium carbonate in alkali-promoted hydrotalcite-based material. Moreover, it has been clearly shown that crystalline magnesium carbonate may be reversibly formed at temperatures above 300 °C in the presence of sufficient partial pressure of steam in the gas phase, conditions that are prevalent in pre-combustion CO(2) capture. The role of steam appears to be of utmost importance for the formation of the bulk carbonate phase and for its reversibility. It is proposed that a high partial pressure of steam keeps the magnesium oxide periclase phase sufficiently hydroxylated to allow magnesium carbonate formation if a relatively high partial pressure CO(2) is present in the gas phase.

Improved carbon dioxide capture using metal reinforced hydrotalcite under wet conditions

“…The CO 2 adsorption capacities at these cycles were 0.26, 0.74 and 1.035, represented by capacity drop of 0.03, 0.048 and 0.074 mol/kg, respectively. This suggests that desorption under wet condition activated the adsorption sites by maintaining the hydroxyl on the surface, and preventing the sites from being poisoned (Béarat et al, 2002;Walspurger et al, 2010). Fig.…”

Facile Synthesis of High-Surface-Area Mesoporous MgO with Excellent High-Temperature CO2 Adsorption Potential

“…22,23 One of the intriguing facts about magnesium aluminum mixed oxides is that the aluminum oxide phase has minimum interaction with CO 2 and the active phase responsible for the adsorption of CO 2 is mainly magnesium oxide. 24 Aluminum oxide phase is said to enhance the capacity by maintaining the small magnesium oxide particles in dispersed state and thus removing the diffusion limitations associated with bulk magnesium oxide. 24,25 This suggests that high surface area nano-sized magnesium oxide can also be a promising candidate for high temperature CO 2 capture.…”

In situ X-ray diffraction of CaO based CO2 sorbents

“…Amorphous materials can be determined from XRD via the presence of extremely broad diffuse scattering. 47,53,54 The quality of the refinements can be gauged using the residual, which is the difference between the model and the data (Fig. 1).…”