Novel Low Cost Two-dimensional Atomically Precise Covalent Organic Membranes

Reducing the amount of carbon dioxide emissions from burning fossil fuels has been dentified as one of the most important and difficult problems facing our society. The post combustion CO2 capture from flue gas is particularly challenging due to the relatively low pressure (1 atm) and high temperature (~70 ºC) of flue gas, and its small CO2 concentration (<15%). This requires a highly efficient and selective separation process from a high volume of flue gas that contains other competing components (mainly N2 70–75%, H2O 5– 7%, and O2 3–4%). This proposal provides a transformational pathway for the development of new generation of 2D atomically precise covalent organic membranes with tailored carbon capture functionality. Statement of How this Problem or Situation is Being Addressed: The proposed membranes represent a highly promising class of materials with exceptional chemical/thermal stability and tunable porosity that can provide a much-needed solution to the carbon capture problem. We plan to develop a new generation of low-cost, large area, defect free 2D atomically precise membranes with controlled pore size and functionalities tailored for optimal CO2 selectivity. We envision one key strategy to develop novel 2D covalent organic membranes with improved performance is to custom build their pores (pore size and functionality) via pore engineering for specific CO2 binding. What was done in Phase I: Nine different organic linkers and nodes with CO2-philic function groups have been successfully synthesized. Four 2D polyimine membranes based on the synthesized linkers and nodes have been fabricated. SEM and STM measurements confirmed no obvious defect. Gas separation test shows the fabricated membranes have promising selectivity when the flux is high. What is planned for the Phase II project: The gas separation performance will be further improved by optimizing the pore size (including longer side chains and photo-responsive moieties) and thickness. More direct evidence to prove the atomically precise feature of 2D covalent organic membranes at nanometer level will be obtained. Commercial Applications and Other Benefits: The excellent CO2 permeance and selectivity features of such a new class of 2D covalent organic membranes will ultimately make them very promising for many applications, such as flue gas treatment at power plants and high performance automobile exhaust gas treatment systems.