The Department of Chemistry invites you to its departmental seminar today, Monday, March 9, at 4:10 p.m. in Fulmer Hall, room 438.
Dr. Bess Vlaisavljevich from the University of California Berkeley will present CO2 adsorption in a family of diamine-appended metal organic frameworks.
Abstract: Advanced solid adsorbents have the potential to significantly decrease the cost of CO2 removal from flue gas of fuel-burning power plants. In particular, the diamine-appended metal-organic frameworks mmen-M2(dobpdc) (mmen = N,N′-dimethylethylenediamine; M = Mg, Mn, Fe, Co, Zn; dobpdc4– = 4,4′-dioxidobiphenyl-3,3′-dicarboxylate) behave as “phase-change” adsorbents and are of interest for their water stability. These materials exhibit unusual step-shaped CO2 adsorption isotherms that shift dramatically with temperature. Furthermore, the pressure at which this step occurs as well as the heat of adsorption is metal dependent. We demonstrate via quantum chemical calculations that the amines should not be considered firmly anchored to the framework and explore the mechanism for CO2 adsorption. An ammonium carbamate species is formed via the insertion of CO2 into the Mg-Namine bonds. Using a simple Langmuir model, we translate the quantum chemical results into isotherms using a coarse grained Monte Carlo simulation technique and show that this adsorption mechanism can explain the characteristic step observed in the experimental isotherm while a previously proposed mechanism cannot. The metal CO2 binding energies show a metal dependence corresponding to the M-Namine bond strength. We show that this difference can be exploited to tune the pressure at which the step in the isotherm occurs.
Contact: Chelsea (Pickett) Gao, chelsea.m.pickett@wsu.edu.
