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

Abstract

Bi-functional Ni–hollow CaO stabilized by ALD-grown Al2O3 overcoat for sorption-enhanced water-gas shift reaction producing high purity hydrogen.

Chemical looping beyond combustion – a perspective

“…395 The WGS reaction is relevant also in gasification reactions, and generally in schemes where mixtures of CO, CO 2 , H 2 and H 2 O co-exist at high temperature, and so sorbents for CO 2 are conventionally used. 396 Lately, CaO-based sorbents have also gained considerable attention for carbonate looping (CaL), [397][398][399][400][401][402][403][404][405] a postcombustion CO 2 capture technique. 402,406 A key advantage of using CaO for the sorption of CO 2 is its high theoretical uptake of 0.78 g CO 2 per g CaO, according to reaction (R68) in Table 2.…”

CO2 capture using solid sorbents: Fundamental aspects, mechanistic insights and recent advances

“…The advantage of the ALD technique is that it enables control of the layer thickness at the atomic scale and can provide a thin conformal coating. The technique has been applied to layer coatings of thickness between 1 nm to 30 nm of stabilizer oxides on a porous CaO support to create core-shell structures for CO2 capture [119], [120], [378], [397], [399], [410]. It is worth mentioning that the core-shell structure is formed in the as-prepared materials but it also tends to collapse during multiple cycle operation [412].…”

“…The economic attractiveness of the calcium looping process increases further if (besides CO2 capture) products are generated that have a certain value, e.g. hydrogen (sorption-enhanced reforming or water-gas shift) [399], [596], [647]- [656] or thermal energy (thermochemical energy storage) [657]- [668], and may therefore accelerate the implementation at the industrial scale. What is certainly missing currently are demonstration units that prove that the different processes employing metal oxide sorbents for CO2 work reliably at the industrial scale.…”

Structural insight into an atomic layer deposition (ALD) grown Al2O3 layer on Ni/SiO2: impact on catalytic activity and stability in dry reforming of methane

“…8 Ni 0 is proposed to be the catalytically active state for DRM, and a linear relationship between the DRM activity and the quantity of surface Ni has been reported. 5,[9][10][11][12] However, under DRM conditions, Ni-based catalysts are prone to rapid deactivation due to a combination of various factors including coke formation, 13,14 metal oxidation followed by the migration of Ni into the support, 11,[15][16][17] and sintering of the Ni particles. 18,19 The fact that the Tammann temperature of Ni (≈700 °C) is below the envisioned operating temperatures of the DRM process (≈900 °C) makes sintering a serious issue.…”