Influence of Alkali Metals (Na, K, and Cs) on CO₂ Adsorption by Layered Double Oxides Supported on Graphene Oxide

Abstract

The CO 2 adsorption capacities, isotherms, and thermal stability of sodium, potassium, and cesium impregnated layered double oxides (LDOs) supported on graphene oxide (GO) are reported. Alkali cations were found to modify the distribution and density of chemisorption sites resulting in higher CO 2 adsorption capacities at 573 K (0.56−0.69 molCO 2 /kg) compared to the unpromoted adsorbents (0.29 molCO 2 /kg) (LDO and LDO/GO hybrids). The improved thermal stability imparted by incorporation of GO in the LDO was not compromised by the addition of any of the alkali species. Potassium produced the most marked enhancement in CO 2 capacity (0.47 molCO 2 /mol alkali) due to its relatively strong Lewis basicity and even distribution on the surface of the adsorbents. Cesium was found to have a tendency to agglomerate that reduced the effectiveness of promotion. The CO 2 adsorption equilibrium of the fresh calcined materials is described by the Freundlich model. After thermal adsorption−desorption cycles the isotherms fit closer to the Langmuir isotherm.

Recent progress in materials development for CO2conversion: issues and challenges

“…Nowadays, direct air capture (DAC) is a well-known strategy, since it often deals with CO 2 at ultra-dilute conditions. 41,42 Several materials have shown potential for DAC purposes, [43][44][45][46][47][48][49] such as carbonaceous adsorbents, zeolitic materials, MOFs, alkali metal carbonate, amine loaded solid adsorbents, etc. Several potential adsorbents for direct CO 2 capture are presented in Fig.…”

Towards autothermal hydrogen production by sorption-enhanced water gas shift and methanol reforming: A thermodynamic analysis

“…2 -1 was assumed. The value was measured by Ding et al[ 30 ] from CO 2 Langmuir-adsorption isotherms at 673 K and 753 K (in the Henry's region) under wet conditions for layered double oxides, which are promising adsorbents for sorptionenhanced H 2 production [30,31,32]. As discussed in section 2.1, the equilibrium calculations presented in this study assume that CO 2 is the only species that is adsorbed on the surface.…”

DFT Insights into the Interfacial Chemical Behavior of Hybrid LDH/GO Nanocomposites

“…Combining various building blocks together to form a well-designed hierarchical composite structure is a popular method of designing new materials with improved physical and chemical properties in materials science areas. − Layered double hydroxides (LDHs) and graphene oxide (GO) are two promising and extensively studied building blocks both with two-dimensional (2-D) lamellar structures. LDH has a chemical composition of [M 1– x 2+ M x 3+ (OH) 2 ] x + A x / n n · n H 2 O, where M 2+ , M 3+ , and A n – represent divalent metal cation, trivalent metal cation, and interlayer anion, respectively. , The LDH bulk flakes can be easily delaminated into single-layer structures. ,− The single-layer LDH is positively charged because of the substitution of divalent cations by trivalent cations, which makes it easy to restack . The GO single sheet is negatively charged because of the various oxygen-containing functional groups on its basal plane. , It has become a promising support material to tackle the restacking problem of LDH by combining LDH and GO, furthermore yielding a LDH/GO nanocomposite …”

“…1,6−8 The single-layer LDH is positively charged because of the substitution of divalent cations by trivalent cations, which makes it easy to restack. 9 The GO single sheet is negatively charged because of the various oxygen-containing functional groups on its basal plane. 10,11 It has become a promising support material to tackle the restacking problem of LDH by combining LDH and GO, furthermore yielding a LDH/GO nanocomposite.…”