title: Metal-substituted zeolitic imidazolate framework ZIF-108: gas-sorption and membrane-separation properties.
abstract: A series of dual-metal zeolitic imidazolate framework (ZIF) crystals with SOD and RHO topologies was synthesised by metal substitution from ZIF-108 (Zn(2-nitroimidazolate)2 , SOD topology) as the parent material. This was based on the concept that metal substitution of ZIF-108 requires a much lower activation energy than homogenous nucleation owing to the metastability of ZIF-108. In-depth investigations of the formation processes of the daughter ZIFs indicated that the transformation of ZIF-108 is a dissolution/heterogeneous nucleation process. Typical isostructural Co(2+) substitution mainly occurs at the outer surface of ZIF-108 and results in a core-shell structure. On the contrary, the Cu(2+) -substituted ZIF has a RHO topology with a homogeneous distribution of Cu(2+) ions in the structure. Substitution with Ni(2+) resulted in a remarkable enhancement in adsorption selectivity toward CO(2) over N(2) by a factor of up to 227. With Co(2+) -substituted nanoparticles as inorganic filler, a mixed matrix membrane based on polysulfone displayed greatly improved performance in the separation of H(2)/CH(4), CO(2)/N(2) and CO(2)/CH(4).
authors: State Key Laboratory of Catalysis, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, 457 Zhongshan Road, Dalian 116023 (P. R. China), Fax: (+86) 411-846-94447; University of Chinese Academy of Sciences, 19A Yuquan Road, Beijing 100049 (P. R. China).
authors: Yujie
authors: Y
authors: Ban
authors: Yanshuo
authors: Y
authors: Li
authors: Yuan
authors: Y
authors: Peng
authors: Hua
authors: H
authors: Jin
authors: Wenmei
authors: W
authors: Jiao
authors: Xinlei
authors: X
authors: Liu
authors: Weishen
authors: W
authors: Yang
mesh_terms: D000327:Adsorption; D005740:Gases / Q000302:isolation & purification*; D007093:Imidazoles / Q000737:chemistry*; D008567:Membranes, Artificial; D008958:Models, Molecular; D009942:Organometallic Compounds / Q000737:chemistry*; D017641:Zeolites / Q000737:chemistry*; D015032:Zinc / Q000737:chemistry
chemical_list: D005740:Gases; D007093:Imidazoles; D008567:Membranes, Artificial; D009942:Organometallic Compounds; D017641:Zeolites; D015032:Zinc
keywords: adsorption; membranes; metal-organic frameworks; zeolite analogues; zinc