Prussian Blue Analogues for CO₂ and SO₂ Capture and Separation Applications

Abstract

Adsorption isotherms of pure gases present in flue gas including CO(2), N(2), SO(2), NO, H(2)S, and water were studied using prussian blues of chemical formula M(3)[Co(CN)(6)](2).nH(2)O (M = Co, Zn) using an HPVA-100 volumetric gas analyzer and other spectroscopic methods. All the samples were characterized, and the microporous nature of the samples was studied using the BET isotherm. These materials adsorbed 8-10 wt % of CO(2) at room temperature and 1 bar of pressure with heats of adsorption ranging from 200 to 300 Btu/lb of CO(2), which is lower than monoethanolamine (750 Btu/lb of CO(2)) at the same mass loading. At high pressures (30 bar and 298 K), these materials adsorbed approximately 20-30 wt % of CO(2), which corresponds to 3 to 5 molecules of CO(2) per formula unit. Similar gas adsorption isotherms for SO(2), H(2)S, and NO were collected using a specially constructed volumetric gas analyzer. At close to 1 bar of equilibrium pressure, these materials sorb around 2.5, 2.7, and 1.2 mmol/g of SO(2), H(2)S, and NO. In particular, the uptake of SO(2) and H(2)S in Co(3)[Co(CN)(6)](2) is quite significant since it sorbs around 10 and 4.5 wt % at 0.1 bar of pressure. The stability of prussian blues before and after trace gases was studied using a powder X-ray diffraction instrument, which confirms these materials do not decompose after exposure to trace gases.

Cyanide-bridged bimetallic multidimensional structures derived from organotin(IV) and dicyanoaurate building blocks: ion exchange, luminescence, and gas sorption properties

“…Recently, Long and others published a series of paper using Prussian blue analogues for hydrogen storage at 77 K [44,45]. In addition to the promising H 2 storage materials, the cyano-bridged frameworks may be useful for CO 2 storage and separation applications [46,47].…”

“…This could be due to the fact that the unsaturated metal centers of the framework interact with O 2 more strongly than with N 2 [49]. Other cyano-bridged coordination solids containing coordinatively unsaturated metal centers have been shown to interact with H 2 at high loading [44,45]. The maximum O 2 uptake is 3.39 wt.%, which corresponds to approximately 0.67 O 2 molecules per formula unit of 2.…”

Competitive adsorption study of CO2 and SO2 on CoII3[CoIII(CN)6]2 using DRIFTS

“…1 was used to estimate the ratio of the sensitivity factors for the characteristic peaks for CO 2 (ad) at 2339 cm −1 and SO 2 (ad) at 1146 cm −1 that were selected as the molecular markers in this study. Sorption data from Thallapally et al [5] indicate that approximately 6.25 times as much SO 2 (per mole) is adsorbed than CO 2 on CoCo, in separate experiments at 298 K when each gas is at ∼10 kPa. Consequently,…”

“…First, the gas is a known component of CO 2 waste streams at concentrations on the order of 1% (taken as mole percent in this study). It is also being investigated in volumetric sorption studies on CoCo in our laboratory [5], is strongly infrared active in the gas phase, and the occurrence of infrared peaks due to adsorbed SO 2 seemed likely since recent transmission studies have reported them for other adsorbents [6,7]. Finally, while the two gases are not isostructural, their molecular diameters are comparable suggesting they might be similarly accommodated within the pores of CoCo.…”

Metal‐Organic Frameworks: Harmful Gas Removal

“…Moreover, the adsorbed SO 2 can be readily released, and the NOTT-300 regenerated at ambient temperatures without the need for heating, indicating an easy-on/easy-off capture system. Thallapally et al 65 studied SO 2 and H 2 S adsorption in some Prussian blue analogs, M 3 [Co(CN) 6 ] 2 ⋅ nH 2 O (M = Co, Zn). They showed that the Co 3 [Co(CN) 6 ] 2 can adsorb a significant amount of SO 2 and H 2 S, with capacities of 10 and 4.5 wt% at 100 kPa, respectively.…”