Synthesis and Characterization of Rationally Designed Porous Materials for Energy Storage and Carbon Capture

Abstract

Two of the hottest areas in porous materials research in the last decade have been in energy storage, mainly hydrogen and methane, and in carbon capture and sequestration (CCS). Although these topics are intricately linked in terms of our future energy landscape, the specific materials needed to solve these problems must have significantly different properties. High pressure gas storage is most often linked with high surface areas and pore volumes, while carbon capture sorbents require high sorption enthalpies to achieve the needed selectivity. The latter typically involves separating CO2 from mixed gas streams of mostly nitrogen via a temperature swing adsorption (TSA) process. Much of the excitement has arisen because of the potential of metal-organic frameworks (MOFs) and porous polymer networks (PPNs). Both classes of materials have extremely high surface areas (upwards of 4000 m2/g) and can be modified to have specific physical properties, thus enabling high performance materials for targeted applications. This dissertation focuses on the synthesis and characterization of these novel materials for both applications by tuning framework topologies, composition, and surface properties.

Specifically, two routes to synthesize a single molecule trap (SMT) highlight the flexibility of MOF design and ability to tune a framework to interact with specifically one guest molecule; computational and experimental evidence of the binding mechanism are shown as well. Furthermore, eight PPNs are synthesized and characterized for post-combustion carbon capture and direct air capture applications. In addition a high-throughput model, grounded in thermodynamics, to calculate the energy penalty associated with the carbon capture step is presented in order to evaluate all materials for TSA applications provide a comparison to the state of the art capture technologies. This includes results of working capacity and energy calculations to determine parasitic loads (per ton of CO2 captured) from readily available experimental data of any material (adsorption isotherms and heat capacities) using a few simple equations. Through various systematic investigations, trends are analyzed to form structure property relationships that will aid future material development.