2007 Spring Symposium

 
Jaime R. Blan­ton^1*, Taku­ma Hara², Kon­rad Möbus³ and Baoshu Chen^3
1Degus­sa Corporation,5150 Gilbertsville High­way, Calvert City, KY 42029 (USA)
²Degus­sa Japan, Tsuku­ba Mina­mi Dai­ichi Kogyo Danchi, 21 Kasum­i­nosato Ami-machi, Inashi­ki-gun Ibara­ki-ken 300‑0315 (Japan)
³Degus­sa Ag,Rodenbacher Chaussee 4, 63457 Hanau-Wolf­gang (Ger­many)
^*jaime.​blanton@​degussa.​com

Abstract — ε-capro­lac­tam is a feed­stock for nylon-6 poly­mers. The demand for ε-capro­lac­tam was 4 mil­lion met­ric tons in 2005. Hydrox­y­lamine (hyam) is a key raw mate­r­i­al for the man­u­fac­ture of ε-capro­lac­tam. The hydrox­y­lamine used in the HPO™ is pro­duced by selec­tive hydro­gena­tion of nitric acid over a Pd/C cat­a­lyst. Degus­sa has done exten­sive work to devel­op Pd/C cat­a­lysts with supe­ri­or activ­i­ty for the pro­duc­tion of hyam (Equa­tion 1).

Equa­tion 1: NO₃⁻ + 3H₂ + 2H⁺ → NH₃OH⁺ + 2H₂O

Many para­me­ters influ­ence the per­for­mance of a cat­a­lyst. Our aim was to see how vary­ing the car­bon sup­port, Pd load­ing and Pt addi­tion would affect the activ­i­ty, selec­tiv­i­ty and fil­ter­abil­i­ty of the cat­a­lyst in hopes of iden­ti­fy­ing the opti­mal cat­a­lyst for the hyam reac­tion (activ­i­ty greater than 25 g hyam/g Pd, selec­tiv­i­ty >; 90% and fast fil­tra­tion rate).

Numer­ous cat­a­lysts were pre­pared by sev­er­al dif­fer­ent meth­ods and test­ed for their hyam activ­i­ty. Cat­a­lysts (six in total; A-F) pre­pared using the method that pro­vid­ed the most active cat­a­lysts were used in this study. These cat­a­lysts were each pre­pared by the same pro­pri­etary pro­ce­dure and each con­tains 10% Pd except D which con­tains 9% Pd. In a typ­i­cal test 750 mg of cat­a­lyst was added to a con­tin­u­ous stirred tank reac­tor (1500 rpm) con­tain­ing the nitrate ions in 1L of phos­phate buffer solu­tion. The amount of hyam formed and selec­tiv­i­ty after 90 min at 30 °C were mea­sured by titra­tion. Cat­a­lyst fil­tra­tion rates were mea­sured by pass­ing a slur­ry of buffer solu­tion con­tain­ing 5 g cat­a­lyst through a fil­ter cloth at 0.1 MPa N₂ pres­sure.

From this study it is evi­dent that sev­er­al high­ly active hyam cat­a­lysts have been devel­oped for the HPO™ process. Depend­ing on which per­for­mance indi­ca­tor is most impor­tant (activ­i­ty, selec­tiv­i­ty or fil­ter­abil­i­ty) one can select the best Degus­sa cat­a­lyst for their appli­ca­tion.
 
Table 1: Activ­i­ty (g hyam/g Pd) and selec­tiv­i­ty for bimetal­lic cat­a­lysts and cat­a­lysts of vary­ing Pd load­ings.

 
Fig­ure 1: Hyam activ­i­ty vs. fil­tra­tion of cat­a­lysts.

2007 Spring Symposium

 
Wolf­gang Ruet­tinger
BASF Cat­a­lysts LLC
101 Wood Avenue
Iselin, NJ 08830 USA
wolfgang.​ruettinger@​BASF.​com

Abstract — In the devel­op­ment of mono­lith­ic cat­a­lysts for hydro­gen pro­duc­tion, one has to devel­op cat­a­lysts with suf­fi­cient activ­i­ty and selec­tiv­i­ty to be com­mer­cial­ly viable. In addi­tion, the cat­a­lyst has to endure the oper­at­ing con­di­tions encoun­tered in fuel proces­sors and have a suf­fi­cient use­ful life­time.

Real­is­tic test pro­to­cols and accel­er­at­ed aging tests play an impor­tant role in deter­min­ing the dura­bil­i­ty of cat­a­lysts. In auto­mo­tive three-way cat­a­lyst, there is a vast data­base of mil­lions of used cat­a­lysts and the preva­lent fail­ure modes were exten­sive­ly stud­ied. This is not the case in fuel proces­sors for hydro­gen pro­duc­tion. With very lim­it­ed field data, we have to design tests which mim­ic the most dam­ag­ing con­di­tions encoun­tered using lab­o­ra­to­ry reac­tors and deter­mine pos­si­ble fail­ure modes.

I will show exam­ples of test pro­to­cols devel­oped at BASF Cat­a­lysts (for­mer­ly Engel­hard). Test­ing of water gas shift cat­a­lysts demon­strate how start-stop oper­a­tions with var­i­ous start-stop cycles can be among the most dam­ag­ing oper­a­tions to the cat­a­lysts. Results of the tests form the basis for trou­bleshoot­ing of cat­a­lysts prob­lems in the appli­ca­tion. Fun­da­men­tal knowl­edge gained dur­ing exam­i­na­tion of cat­a­lysts oper­at­ed in these tests can influ­ence future cat­a­lyst design.

2007 Spring Symposium

 
Eseoghene Jero­ro and John M. Vohs
Depart­ment of Chem­i­cal and Bio­mol­e­c­u­lar Engi­neer­ing
Uni­ver­si­ty of Penn­syl­va­nia
Philadel­phia, PA 19104–6393 USA
ejeroro@​seas.​upenn.​edu

Abstract — Methanol and oth­er alco­hols are poten­tial bio-renew­able sources of hydro­gen. The use of alco­hols, how­ev­er, as a source of H₂ or for H₂ stor­age requires sta­ble reform­ing cat­a­lysts that have high activ­i­ty at low tem­per­a­tures. One such cat­a­lyst that has received much atten­tion for steam reform­ing of CH₃OH (SRM) [CH₃OH + H₂O → CO₂ + 3H₂] is Pd sup­port­ed on ZnO. Pd/ZnO cat­a­lysts have unusu­al­ly high selec­tiv­i­ty (>;95%) for the pro­duc­tion of CO₂ and H₂ from methanol, in spite of the fact that bulk Pd exhibits near­ly 100 % selec­tiv­i­ty for the dehy­dro­gena­tion of CH₃OH to CO and H₂ under typ­i­cal SRM con­di­tions. Iwasa and oth­ers have demon­strat­ed that par­tial alloy­ing of the Pd with Zn is required to obtain a high­ly selec­tive Pd/ZnO SRM cat­a­lyst. While the impor­tance of alloy for­ma­tion has been estab­lished, the mech­a­nism by which Zn alters the selec­tiv­i­ty to pro­duce CO₂ rather than CO is not under­stood. Iwasa et al. have pro­posed, how­ev­er, that the dra­mat­ic change in selec­tiv­i­ty may result from the desta­bi­liza­tion of η2-CH₂O inter­me­di­ates in which the car­bonyl group is par­al­lel to the sur­face and bond­ing is by both the C and O atoms in favor of η1-CH₂O in which the car­bonyl is per­pen­dic­u­lar to the sur­face and only the oxy­gen inter­acts with the met­al. Pre­sum­ably this lat­er species is more resis­tant to dehy­dro­gena­tion and reacts with hydrox­yl groups to pro­duce CO₂ and H₂.

In order to elu­ci­date how alloy­ing with Zn affects the CH₃OH dehy­dro­gena­tion activ­i­ty of Pd, the struc­ture and reac­tiv­i­ty of mod­el cat­a­lysts con­sist­ing of sub­mono­lay­er amounts of Zn sup­port­ed on a Pd(111) sin­gle crys­tal have been inves­ti­gat­ed. I will present tem­per­a­ture pro­grammed des­orp­tion (TPD) data for the reac­tion of methanol and formalde­hyde on Pd(111) as a func­tion of Zn cov­er­age as well as results of a high res­o­lu­tion elec­tron ener­gy loss spec­troscopy (HREELS) study of the bond­ing con­fig­u­ra­tions of CO, CH₂O, and CH₃OH on Zn/Pd(111) sur­faces. TPD data for the reac­tion of methanol on Pd sup­port­ed on ZnO(0001) sin­gle crys­tal sur­faces will also be pre­sent­ed. The TPD data shows that the for­ma­tion of the Pd Zn alloy severe­ly shuts down the dehy­dro­gena­tion of CH₃OH and CH₂O which cor­re­sponds to the increase in η1-CH₂O seen in the HREELS. Over­all, these results pro­vide fun­da­men­tal insight into how Zn alters the reac­tiv­i­ty of Pd for the dehy­dro­gena­tion of CH₃OH and this insight is use­ful in elu­ci­dat­ing the mech­a­nism of the steam reform­ing of methanol on Pd/ZnO cat­a­lysts.

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.