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Physical Adsorption on a Zr Metal-Organic Framework

Oscar Vilches, University of Washington
Thursday, January 4, 2018 - 12:30pm to 1:30pm
PAT C-520

A Metal-Organic Frameworks (MOF) is an extremely porous material synthesized by joining metal containing crystalline inorganic nodes with single filament or layer of an organic compound to form a regular pores macroscopic crystalline structure. Typical adsorption capacities are in the equivalent of thousands of square meters per gram. There are tens of thousands of these materials, with geometrical and particular metal characteristics tailored to specific applications in catalysis, gas separation, storage, molecular motors, etc. We took one particular MOF (a Zr-MOF, called NU-1000, synthesized at Northwester U.) which had been studied previously by structural, adsorption and calorimetric techniques, to do a survey of the physical adsorption characteristics of ten Van der Waals gases from hydrogen to ethane. We measured adsorption isotherms in the range from 16K to 155K, as appropriate for each gas, to obtain the heat of adsorption of the different species as a function of pore filling. Density functional calculations from collaborators identified the most important initial adsorption sites and provided calculated heats of adsorption at zero coverage to compare to the initial adsorption experiment ones. The filling of the pores past the completion of a statistical monolayer will be briefly discussed.​