title: Prussian blue analogues for CO(2) and SO(2) 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.
authors.affiliation: Energy and Environment Directorate, Pacific Northwest National Laboratory, Richland, Washington 99352, USA. Praveen.Thallapally@pnl.gov
authors.forename: Praveen K
authors.initials: PK
authors.lastname: Thallapally
authors.forename: Radha Kishan
authors.initials: RK
authors.lastname: Motkuri
authors.forename: Carlos A
authors.initials: CA
authors.lastname: Fernandez
authors.forename: B Peter
authors.initials: BP
authors.lastname: McGrail
authors.forename: Ghorishi S
authors.initials: GS
authors.lastname: Behrooz
mesh_terms: D000327:Adsorption; D002245:Carbon Dioxide / Q000737:chemistry / Q000302:isolation & purification*; D005295:Ferrocyanides / Q000737:chemistry*; D011312:Pressure; D013458:Sulfur Dioxide / Q000737:chemistry / Q000302:isolation & purification*; D013696:Temperature
chemical_list: D005295:Ferrocyanides; D013458:Sulfur Dioxide; D002245:Carbon Dioxide; C000170:ferric ferrocyanide