TY - JOUR
T1 - Hydrogen storage in zeolite-like hexacyanometallates
T2 - Role of the building block
AU - Reguera, L.
AU - Balmaseda, J.
AU - Krap, C. P.
AU - Avila, M.
AU - Reguera, E.
PY - 2008/11/6
Y1 - 2008/11/6
N2 - Hydrogen storage in zeolite-like hexacyanometallates, Zn3A 2[M(CN)6]2 with A = K, Rb, Cs, and M = Fe, Ru, Os, was studied. In a previous article, we have reported the role of the exchangeable metal (A) for M = Fe on the H2 adsorption. This contribution concerns to the effect of the molecular block, [M(CN)6], on the recorded H2 adsorption isotherms and the corresponding adsorption heats. This family of porous materials can be considered as octahedral anionic blocks, [M(CN)6]4-, assembled by zinc (2+) atoms linked at their nitrogen ends. The porous framework topology was described from the refined crystal structures. In the resulting 3D network the zinc atom is found with a tetrahedral coordination. This leads to formation of ellipsoidal cavities, of about 12.5 × 9 × 8 Å, which remain communicated by elliptical windows. The H2 adsorption heat was estimated using the isosteric method from isotherms recorded at 75 and 85 K. The estimated values for the adsorption heats follow the order: Os > Ru > Fe. The building block contribution to the H2 adsorption potential takes place through the charge derealization from the inner metal (M) to increase the electric field gradient at the cavity surface. The CO2 adsorption isotherms are also conclusive on the contribution of the building block to the cavity adsorption potential. All of the studied samples were characterized from X-ray diffraction, infrared, and thermogravimetric data.
AB - Hydrogen storage in zeolite-like hexacyanometallates, Zn3A 2[M(CN)6]2 with A = K, Rb, Cs, and M = Fe, Ru, Os, was studied. In a previous article, we have reported the role of the exchangeable metal (A) for M = Fe on the H2 adsorption. This contribution concerns to the effect of the molecular block, [M(CN)6], on the recorded H2 adsorption isotherms and the corresponding adsorption heats. This family of porous materials can be considered as octahedral anionic blocks, [M(CN)6]4-, assembled by zinc (2+) atoms linked at their nitrogen ends. The porous framework topology was described from the refined crystal structures. In the resulting 3D network the zinc atom is found with a tetrahedral coordination. This leads to formation of ellipsoidal cavities, of about 12.5 × 9 × 8 Å, which remain communicated by elliptical windows. The H2 adsorption heat was estimated using the isosteric method from isotherms recorded at 75 and 85 K. The estimated values for the adsorption heats follow the order: Os > Ru > Fe. The building block contribution to the H2 adsorption potential takes place through the charge derealization from the inner metal (M) to increase the electric field gradient at the cavity surface. The CO2 adsorption isotherms are also conclusive on the contribution of the building block to the cavity adsorption potential. All of the studied samples were characterized from X-ray diffraction, infrared, and thermogravimetric data.
UR - http://www.scopus.com/inward/record.url?scp=56549125966&partnerID=8YFLogxK
U2 - 10.1021/jp802764v
DO - 10.1021/jp802764v
M3 - Artículo
SN - 1932-7447
VL - 112
SP - 17443
EP - 17449
JO - Journal of Physical Chemistry C
JF - Journal of Physical Chemistry C
IS - 44
ER -