Papers by Michael Dworzak
Chemistry – A European Journal, 2021
Molecules with permanent porosity in the solid state have been studied for decades. Porosity in t... more Molecules with permanent porosity in the solid state have been studied for decades. Porosity in these systems is governed by intrinsic pore space, as in cages or macrocycles, and extrinsic void space, created through loose, intermolecular solid-state packing. The development of permanently porous molecular materials, especially cages with organic or metal-organic composition, has seen increased interest over the past decade and as such, incredibly high surface areas have been reported for these solids. Despite this, examples where these materials have been explored for gas storage applications are relatively limited. This minireview outlines existing molecular systems that have been investigated for gas storage and highlights strategies that have been used to understand adsorption mechanisms in porous molecular materials.
A useful correlation between the low-pressure (up to 1.2 bar) low-temperature (195 K) and high-pr... more A useful correlation between the low-pressure (up to 1.2 bar) low-temperature (195 K) and high-pressure (up to 65 bar) room temperature (298 K) methane storage properties of a range of porous materials is reported. Methane isotherms under these two sets of conditions show a remarkable agreement in both equilibrium adsorption and deliverable capacities for materials with pore volumes that are less than approximately 0.80 cm3/g. This trend holds well for the suite of metal-organic frameworks and porous coordination cages we studied, in addition to a zeolite and porous organic cage. Although it is well known that gravimetric gas storage capacity trends with gravimetric surface area, the 1.2 bar, 195 K excess adsorption capacity of a given framework is a better indicator of its room temperature, 65 bar capacity. Given the significantly smaller sample quantities needed for low-pressure measurements, greater accessibility to researchers around the world, accuracy of the measurement, and higher throughput, we envision this method as a rapid screening tool for the identification of methane storage materials. As excess/total adsorption and gravimetric/volumetric adsorption can be interconverted by simple utilization of the scalar quantities of pore volume or density, respectively, this method can be easily adapted to obtain both gravimetric and volumetric total adsorption capacities for a given adsorbent. In terms of volumetric methane adsorption, we further investigate the rela-tionship between crystallographic and bulk density for the adsorbents studied here. With this analysis, it becomes apparent that in the absence of novel synthetic approaches, reported volumetric storage capacities should be viewed as an optimistic upper limit for a given material and not necessarily a true reflection of its actual adsorption properties as most MOFs have bulk densities that are less than half of their crystallographic values.
Chemical Communications, 2020
This work presents the design, synthesis, and characterization of small lanterns with BET surface... more This work presents the design, synthesis, and characterization of small lanterns with BET surface areas in excess of 200 m2 g−1. These cages represent the lower size limit for permanently microporous coordination cages.
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Papers by Michael Dworzak