Multishelled CaO Microspheres Stabilized by Atomic Layer Deposition of Al₂O₃ for Enhanced CO₂ Capture Performance

Abstract

CO capture and storage is a promising concept to reduce anthropogenic CO emissions. The most established technology for capturing CO relies on amine scrubbing that is, however, associated with high costs. Technoeconomic studies show that using CaO as a high-temperature CO sorbent can significantly reduce the costs of CO capture. A serious disadvantage of CaO derived from earth-abundant precursors, e.g., limestone, is the rapid, sintering-induced decay of its cyclic CO uptake. Here, a template-assisted hydrothermal approach to develop CaO-based sorbents exhibiting a very high and cyclically stable CO uptake is exploited. The morphological characteristics of these sorbents, i.e., a porous shell comprised of CaO nanoparticles coated by a thin layer of Al O (<3 nm) containing a central void, ensure (i) minimal diffusion limitations, (ii) space to accompany the substantial volumetric changes during CO capture and release, and (iii) a minimal quantity of Al O for structural stabilization, thus maximizing the fraction of CO -capture-active CaO.

Runaway Carbon Dioxide Conversion Leads to Enhanced Uptake in a Nanohybrid Form of Porous Magnesium Borohydride

“…Given that global dependence on fossil fuels will necessarily continue in the near term, carbon capture (and sequestration) is widely acknowledged as a necessary carbon abatement strategy. As such, scientific research in recent years has focused with new energy on developing fundamental understanding and control of CO 2 uptake in solid‐state materials . In particular, the molecular level control of CO 2 adsorption/absorption in porous structures with a high density of strong binding sites has been targeted as a means of tailoring their performance for various carbon capture processes.…”

“…For example, porous carbons, zeolite, and metal–organic frameworks (MOFs) have been modified with various N‐functionalities to enhance their reactivity toward CO 2 . Tunable porous solids are capable of achieving both high capacities and high selectivities for binding CO 2 , rendering them potential candidates for postcombustion CO 2 capture at low pressures (<0.15 bar) and mild temperatures (25–70 °C) . Aside from postcombustion CO 2 capture, there is also great interest in materials that can reduce CO 2 concentrations for life support in confined spaces such as in spacecrafts, submarines, or scuba suits .…”

Development of an effective bi-functional Ni–CaO catalyst-sorbent for the sorption-enhanced water gas shift reaction through structural optimization and the controlled deposition of a stabilizer by atomic layer deposition

“…To alleviate the sintering-induced decay of the CO 2 capture capacity of CaO-based CO 2 sorbents, the incorporation of high-T T stabilizers into the CaO matrix has been proposed. Commonly used stabilizers can be classied into two different groups: (i) those forming a mixed oxide with CaO, such as Al 2 O 3 , SiO 2 , TiO 2 and ZrO 2 , [23][24][25][26] and (ii) inert stabilizers that do not react chemically with CaO under the relevant operating conditions, such as MgO, Y 2 O 3 , and ZnO. [27][28][29][30][31] Furthermore, to make calcium looping a viable option at the industrial scale (e.g., operation in circulating uidized beds) high CO 2 uptakes within relatively short residence times are required.…”

Bi-functional Ru/Ca3Al2O6–CaO catalyst-CO2 sorbent for the production of high purity hydrogen via sorption-enhanced steam methane reforming

“…To counteract sintering, attempts have been made to stabilize the CaCO 3 /CaO structure with high Tammann temperature metal oxides such as Al 2 O 3 , MgO, TiO 2 , SiO 2 , and ZrO 2 . [13][14][15][16] As the reaction becomes diffusion-limited at a CaCO 3 thickness of ∼50 nm, 17 also nano-structuring of the sorbent becomes an important aspect to minimize diffusion lengths.…”