2007 Spring Symposium

 
Orest Sko­plyak, Mark A. Barteau, Carl A. Men­ning and Jing­guang G. Chen
Cen­ter for Cat­alyt­ic Sci­ence and Tech­nol­o­gy
Depart­ment of Chem­i­cal Engi­neer­ing
Uni­ver­si­ty of Delaware, Newark, DE 19716

Abstract — The pro­duc­tion of hydro­gen for use in fuel cells can be achieved by selec­tive reform­ing of oxy­genates. The oxy­genates may be derived from renew­able bio­mass and offer advan­tages such as low tox­i­c­i­ty, low reac­tiv­i­ty and com­pat­i­bil­i­ty with the cur­rent infra­struc­ture for trans­porta­tion and stor­age [1]. Plat­inum has been iden­ti­fied as one of the most promis­ing cat­a­lysts for the reform­ing of oxy­genates. In this study, the reac­tions of oxy­genates, such as eth­yl­ene gly­col and ethanol, were inves­ti­gat­ed on 3d-Pt(111) bimetal­lic sur­faces using tem­per­a­ture-pro­grammed des­orp­tion (TPD), high-res­o­lu­tion elec­tron ener­gy loss spec­troscopy (HREELS), and Den­si­ty Func­tion­al The­o­ry (DFT) mod­el­ing [2].

The exper­i­men­tal­ly mea­sured reform­ing activ­i­ty was cor­re­lat­ed with the d-band cen­ter of the bimetal­lic sur­faces from DFT mod­el­ing and dis­played a lin­ear trend for both eth­yl­ene gly­col and ethanol. The reform­ing activ­i­ty increased as the sur­face d-band cen­ter moved clos­er to the Fer­mi lev­el, oppo­site to the trend pre­vi­ous­ly observed for hydro­gena­tion reac­tions. The mod­el­ing results indi­cate that the bind­ing ener­gy of ethanol should increase as the d-band cen­ter of the bimetal­lic sur­face moves clos­er to the Fer­mi lev­el, which can be achieved by choos­ing 3d met­als from the left side of the peri­od­ic table as the sur­face mono­lay­er. The com­bined DFT mod­el­ing and exper­i­men­tal results enabled us to pre­dict bimetal­lic for­mu­la­tions with enhanced reform­ing activ­i­ty. Fur­ther­more, the sta­bil­i­ty of the 3d-Pt(111) sur­faces in oxy­gen-con­tain­ing envi­ron­ment was also inves­ti­gat­ed to under­stand the pos­si­ble bimetal­lic struc­tures dur­ing reform­ing reac­tions [3]. Over­all, the cor­re­la­tion of activ­i­ty and sta­bil­i­ty with the d-band cen­ter allows us to pre­dict oth­er poten­tial bimetal­lic cat­a­lysts based on the d-band cen­ter val­ues in pre­vi­ous cal­cu­la­tions [4,5].

[1] Shabak­er, J. W.; Dav­da, R. R.; Huber, G. W.; Cor­tright, R. D.; Dumesic, J. A. J. Catal. 2003, 215, 344.
[2] Sko­plyak, O.; Barteau, M. A.; Chen, J. G. J. Phys. Chem. B 2006, 110, 1686.
[3] Men­ning, C.A.; Chen, J. G. J. Phys. Chem. B 2006, 110, 15471.
[4] Kitchin, J. R.; Nørskov, J. K.; Barteau, M. A.; Chen, J. G. J. Chem. Phys. 2004, 120, 10240.
[5] Kitchin, J. R.; Nørskov, J. K.; Barteau, M. A.; Chen, J. G. Phys. Rev. Lett. 2004, 93, 156801.