TY - JOUR
T1 - Catalyst Screening through Quantum Chemical Calculations and Microkinetic Modeling
T2 - Hydrolysis of Carbon Dioxide
AU - Ma, Renhu
AU - Schuette, George F.
AU - Broadbelt, Linda J.
N1 - Funding Information:
ACKNOWLEDGMENTS The authors are grateful for the financial support provided by ConocoPhillips and Phillips 66.
Publisher Copyright:
© 2017, Pleiades Publishing, Ltd.
PY - 2017/11/1
Y1 - 2017/11/1
N2 - Quantum chemical calculations are emerging as an effective way to screen catalysts for particular applications. In this contribution, we demonstrate the power of density functional theory to study CO2 hydrolysisby six carbonic anhydrase mimics, evaluating thermodynamic and kinetic parameters at the mechanistic level. A microkinetic model was then built based on the kinetics and thermodynamics calculated from first principles. The intrinsic reaction rate constant was calculated from the results of the microkinetic model and compared with experimental data. Overall, the rate constants were in good agreement with experimental values, except for zinc-tri and complex b, which were overestimated. This was ascribed to their ineffective complexation with Zn2+. How the reaction rate constants vary with time was also investigated. From 0 to 12 ms, the rate constants of complexes a and d decreased to 50 and 67% of their initial values, respectively; the rate constants of complexes b and f2 were almost invariant with time; the rate constant of complex f1 showed an unusual double sigmoidal shape. The pKa values of these six carbonic anhydrase mimics as well as three additional mimics were calculated. A correlation between pKa values and the binding free energy of OH-was obtained by fitting data from five zinc(II) aza-macrocyclic complexes. The reaction rate constants were found to increase linearly with the pKa value, indicating CO2 adsorption is the rate-limiting step.
AB - Quantum chemical calculations are emerging as an effective way to screen catalysts for particular applications. In this contribution, we demonstrate the power of density functional theory to study CO2 hydrolysisby six carbonic anhydrase mimics, evaluating thermodynamic and kinetic parameters at the mechanistic level. A microkinetic model was then built based on the kinetics and thermodynamics calculated from first principles. The intrinsic reaction rate constant was calculated from the results of the microkinetic model and compared with experimental data. Overall, the rate constants were in good agreement with experimental values, except for zinc-tri and complex b, which were overestimated. This was ascribed to their ineffective complexation with Zn2+. How the reaction rate constants vary with time was also investigated. From 0 to 12 ms, the rate constants of complexes a and d decreased to 50 and 67% of their initial values, respectively; the rate constants of complexes b and f2 were almost invariant with time; the rate constant of complex f1 showed an unusual double sigmoidal shape. The pKa values of these six carbonic anhydrase mimics as well as three additional mimics were calculated. A correlation between pKa values and the binding free energy of OH-was obtained by fitting data from five zinc(II) aza-macrocyclic complexes. The reaction rate constants were found to increase linearly with the pKa value, indicating CO2 adsorption is the rate-limiting step.
KW - carbon dioxide hydrolysis
KW - kinetic analysis
KW - microkinetic modeling
KW - quantum chemical calculations
KW - zinc catalysts
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U2 - 10.1134/S0040579517060124
DO - 10.1134/S0040579517060124
M3 - Article
AN - SCOPUS:85042858055
SN - 0040-5795
VL - 51
SP - 949
EP - 960
JO - Theoretical Foundations of Chemical Engineering
JF - Theoretical Foundations of Chemical Engineering
IS - 6
ER -