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.

2007 Spring Symposium

 
Vic­tor S.-Y. Lin
Depart­ment of Chem­istry and U.S. DOE Ames Lab­o­ra­to­ry
Iowa State Uni­ver­si­ty
Ames, Iowa 50011–3111
vsylin@​iastate.​edu

Abstract — We have devel­oped a syn­thet­ic strat­e­gy for mul­ti­func­tion­al­iza­tion of meso­porous sil­i­ca nanopar­ti­cle (MSN) mate­ri­als. This method allows us to tune the rel­a­tive ratio of dif­fer­ent func­tion­al groups and the result­ing par­ti­cle mor­phol­o­gy of MSNs. By intro­duc­ing two organoalkoxysi­lanes as pre­cur­sors in the co-con­den­sa­tion reac­tion, we can uti­lize one pre­cur­sor with stronger struc­ture-direct­ing abil­i­ty to cre­ate the desired pore and par­ti­cle mor­phol­o­gy and employ the oth­er for selec­tive immo­bi­liza­tion of cat­a­lysts. As a proof of prin­ci­ple, we have syn­the­sized and report­ed a series of bifunc­tion­al­ized MSN-based het­ero­ge­neous cat­a­lysts for a vari­ety of car­bonyl acti­va­tion reac­tions, such as aldol, Hen­ry and cyanosi­ly­la­tion reac­tions. By vary­ing the sec­ondary group in the bifunc­tion­al­ized MSN cat­a­lysts, we dis­cov­ered that the selec­tiv­i­ty of a nitroal­dol reac­tion of two com­pet­ing ben­zalde­hy­des react­ing with nitromethane could be sys­tem­at­i­cal­ly tuned sim­ply by vary­ing the physic­o­chem­i­cal prop­er­ties of the pore sur­face-bound sec­ondary groups, i.e. polar­i­ty and hydropho­bic­i­ty.

Fur­ther­more, we have report­ed a bio­mimet­ic coop­er­a­tive cat­alyt­ic sys­tem com­prised of a series of bifunc­tion­al­ized MSN mate­ri­als with var­i­ous rel­a­tive con­cen­tra­tions of a gen­er­al acid and a base group. We were inspired by the fact that enzymes engaged in car­bonyl chem­istry often employ both gen­er­al acid and base cat­alyt­ic residues in the active sites to coop­er­a­tive­ly acti­vate spe­cif­ic sub­strates. In this sys­tem, we have demon­strat­ed that the gen­er­al acid func­tion­al­i­ty could coop­er­a­tive­ly acti­vate sub­strates with the basic group in cat­alyz­ing var­i­ous reac­tions that involve car­bonyl acti­va­tion. By fur­ther uti­liz­ing this approach, we have devel­oped a mixed oxide cat­a­lyst that con­tains both Lewis acidic and basic sites for the syn­the­sis of biodiesel from var­i­ous free fat­ty acid (FFA)-con­tain­ing oil feed­stocks. We have demon­strat­ed that the acid and base func­tion­al­i­ties could coop­er­a­tive­ly cat­alyze both the ester­i­fi­ca­tion of FFAs and the trans­es­ter­i­fi­ca­tion of oils with short-chain alco­hols (e.g. methanol and ethanol) to form alkyl esters (biodiesel). We envi­sion that these mul­ti­func­tion­al­ized MSNs could serve as new selec­tive cat­a­lysts for many oth­er impor­tant reac­tions.

2007 Spring Symposium

 
Den­nis J. Miller
Depart­ment of Chem­i­cal Engi­neer­ing and Mate­ri­als Sci­ence
Michi­gan State Uni­ver­si­ty
East Lans­ing, Michi­gan 48824
(517) 353‑3928
millerd@​egr.​msu.​edu

Abstract — Reduc­tion of oxy­genat­ed bio­mass sub­strates will be a core process in the inte­grat­ed biore­fin­ery in order to pro­duce a suite of petro­le­um analogs for indus­tri­al and con­sumer prod­ucts. In our lab­o­ra­to­ry, we have exam­ined in detail the hydro­gena­tion and hydrogenol­y­sis of bio­mass-derived poly­ols and car­boxylic acids as plat­form inter­me­di­ates for a vari­ety of prod­uct species. This work has involved both fun­da­men­tal efforts to under­stand reac­tion mech­a­nism and sub­strate-cat­a­lyst inter­ac­tions and applied stud­ies to char­ac­ter­ize the effect of sol­vent, sub­strate adsorp­tion, and cat­a­lyst sup­port prop­er­ties. This talk will review our recent find­ings on sev­er­al reac­tion sys­tems includ­ing glyc­erol hydrogenol­y­sis to propy­lene gly­col and lac­tic acid and pro­pi­onic acid hydro­gena­tion to alco­hols. We will illus­trate that car­ry­ing out het­ero­ge­neous cat­alyt­ic reac­tions in aque­ous solu­tion, the “native” reac­tion sol­vent for biore­new­able feed­stocks, pos­es a dif­fer­ent set of chal­lenges than do tra­di­tion­al petro­le­um-based cat­alyt­ic reac­tions.

2007 Spring Symposium

 
Tim­o­thy D. Gierke
DuPont Cen­tral Research and Devel­op­ment
P. O. Box 80328
Wilm­ing­ton, DE 19880–0328
timothy.​d.​gierke@​usa.​dupont.​com

Abstract — With the increas­ing price of oil and the grow­ing empha­sis on sus­tain­able busi­ness prac­tices, many com­pa­nies are look­ing at the oppor­tu­ni­ty to cre­ate new process tech­nol­o­gy to con­vert renew­able resources into new or exist­ing com­mer­cial mate­ri­als. Cat­a­lysts, whether they are chem­i­cal based or bio­log­i­cal­ly based, are con­sis­tent­ly key enabling com­po­nents for these new process­es. This pre­sen­ta­tion will give an overview of DuPont activ­i­ty in this area with an empha­sis on our recent work to devel­op biobased cat­a­lysts and cre­ate new process tech­nol­o­gy for bio­ma­te­ri­als.