H. Guo, PhD, University of New Mexico
The New Direction grant is aimed at the elucidation of the mechanism of methanol steam reforming (MSR) using the plane-wave density functional theory (DFT). In the previous funding year, much progress has been made.
After our initial work on the MSR mechanism on Cu(111),1 we have focused on the MSR mechanism on PdZn.2 It was found that the key steps in the Cu catalyzed MSR are quite similar to those on PdZn. This is expected because the latter has a similar band structure as copper. The results on both catalysts suggested that the selectivity of MSR towards CO2 is due to a facile reaction step between formaldehyde and hydroxyl on the surface. We have further investigated an alternative mechanism involving the methyl formate intermediate. We demonstrated that on both Cu3 and PdZn,4 this pathway plays only a minor role in the catalysis.
Our recent attention has been directed to the methanol decomposition on Pd.5 To this end, we have investigated elementary steps of this process on Pd(211), which serves as a model for stepped Pd defects. In addition, we have developed a kinetic Monte Carlo approach to simulate the thermal programmed desorption (TPD) spectrum. It was found that defect sites are essential if the experimental TPD spectrum is to be reproduced.
(1) Lin, S.; Johnson, R. S.; Smith, G. K.; Xie, D.; Guo, H. Phys. Chem. Chem. Phys. 2011, 13, 9622.
(2) Lin, S.; Xie, D.; Guo, H. J. Phys. Chem. C 2011, 115, 20583.
(3) Lin, S.; Xie, D.; Guo, H. ACS Catal. 2011, 1, 1263.
(4) Lin, S.; Xie, D.; Guo, H. J. Mole. Catal. A 2012, 356, 165.
(5) Lin, S.; Ma, J.; Zhou, L.; Huang, C.; Xie, D.; Guo, H. J. Catal. 2012, submitted.