H-2 Adsorption on Cu(I)-SSZ-13


Ipek B. , Pollock R. A. , Brown C. M. , Üner D. , Lobo R. F.

JOURNAL OF PHYSICAL CHEMISTRY C, cilt.122, ss.540-548, 2018 (SCI İndekslerine Giren Dergi) identifier identifier

  • Yayın Türü: Makale / Tam Makale
  • Cilt numarası: 122
  • Basım Tarihi: 2018
  • Doi Numarası: 10.1021/acs.jpcc.7b09963
  • Dergi Adı: JOURNAL OF PHYSICAL CHEMISTRY C
  • Sayfa Sayıları: ss.540-548

Özet

We report H-2 adsorption capacities reaching 0.05 wt % at 303 K and at 1 atm H-2 pressure on solid-state CuCl-exchanged [Al]-SSZ-13 and [B]-SSZ-13 zeolites. Differential heat of H-2 adsorption is found in the range between 16 and 48 kJ mol H-2(-1) on Cu(I)-SSZ-13 at 323 K and isosteric heat of adsorption is found between 20 and 55 kJ mol H-2(-1) on Cu(I)-[B]-SSZ-13 at temperatures between 293 and 323 K. Strong interactions between H-2 and the copper cations in Cu(I)-SSZ-13 are evidenced using Rietveld refinements of neutron powder diffraction patterns revealing Cu-deuterium (D-2) distances of 2.3(2) and 2.41(1) angstrom. A temperature dependent Cu(I) migration-away from the six-membered ring (6MR) and eight-membered ring (8MR)-is related to the high adsorption capacities of the samples at 303 K. At 10 K, access to Cu(I) at 6MR is sterically hindered by framework oxygen atoms (Cu-O-framework distance of 2.196(5) angstrom), rationalizing the low H-2 adsorption capacities of Cu(I)-SSZ-13 samples as compared to Na-SSZ-13 at 77 K.

We report H2 adsorption capacities reaching 0.05 wt.% at 303 K and at 1 atm H2 pressure on solid-state CuCl-exchanged [Al]-SSZ-13 and [B]-SSZ-13 zeolites. Differential heat of H2 adsorption is found in the range between 16 kJ mol H2
-1 and 48 kJ mol H2 -1 on Cu(I)-SSZ-13 at 323 K and isosteric heat of adsorption is found between 20 kJ mol H2-1 and 55 kJ mol H2-1 on Cu(I)-[B]-SSZ-13 at temperatures between 293 K and 323 K. Strong interactions between H2 and the copper cations in Cu(I)-SSZ-13 are evidenced using Rietveld refinements of Neutron Powder Diffraction patterns revealing Cu–deuterium (D2) distances of 2.3(2) Å and 2.41(1) Å. A temperature-dependent Cu(I) migration—away from the six-membered ring (6MR) and eightmembered ring (8MR)—is related to the high adsorption capacities of the samples at 303 K. At 10 K, access to Cu(I) at 6MR is sterically hindered by framework oxygen atoms (Cu–Oframework distance of 2.196(5) Å), rationalizing the low H2 adsorption capacities of Cu(I)-SSZ-13 samples as compared to Na-SSZ-13 at 77 K.