Novel catalyst architectures for automotive emission control

Meeting Program — April 2018

Johannes W. Schwank
Johannes W. Schwank
James and Judith Street Pro­fes­sor of Chem­i­cal Engi­neer­ing
Depart­ment of Chem­i­cal Engi­neer­ing
Uni­ver­si­ty of Michi­gan
Ann Arbor, Michi­gan

 

Abstract — Two nov­el auto­mo­tive emis­sion con­trol cat­a­lyst archi­tec­tures will be dis­cussed, name­ly core@shell struc­tures for low-tem­per­a­ture three-way cat­a­lysts, and cobalt-based nanorod struc­tures for diesel oxi­da­tion cat­a­lysts that min­i­mize expen­sive plat­inum-group met­als.

Encap­su­lat­ing an active met­al core such as pal­la­di­um in a porous oxide shell mate­r­i­al can lead to improved cat­alyt­ic activ­i­ty, selec­tiv­i­ty, and ther­mal sta­bil­i­ty com­pared to con­ven­tion­al sup­port­ed cat­a­lysts. Main­tain­ing high dis­per­sion of pal­la­di­um is crit­i­cal for Pd-based auto­mo­tive emis­sion con­trol cat­a­lysts, which suf­fer from deac­ti­va­tion due to sin­ter­ing at high tem­per­a­tures (≥ 800 °C). Here, we report direct evi­dence that Pd nanopar­ti­cles (~4 nm) can redis­perse into small nan­oclus­ters after aging at 800 °C, where severe Pd sin­ter­ing would be expect­ed on sup­port­ed Pd cat­a­lysts. The Pd redis­per­sion was con­firmed by in situ, as well as ex situ, high-res­o­lu­tion trans­mis­sion elec­tron microscopy, and is man­i­fest­ed by the decreased CO light-off tem­per­a­ture. These nov­el core@shell struc­tures exhib­it­ed remark­able ther­mal sta­bil­i­ty, main­tain­ing the par­ti­cle size and pore struc­ture at very high tem­per­a­tures (800–900 °C), close to those one may encounter in three-way auto­mo­tive emis­sion con­trol appli­ca­tions.

Co3O4-In2O3 bina­ry oxide nanorods offer a path­way for low-cost, effi­cient diesel emis­sion con­trol sys­tems. The cat­alyt­ic tests results showed that the cat­a­lysts were high­ly active for CO and propene oxi­da­tion, with low tem­per­a­ture light-off curves. The activ­i­ty and sta­bil­i­ty of these cobalt oxide cat­a­lysts were com­pa­ra­ble to plat­inum-based cat­a­lysts, indi­cat­ing that they could be a poten­tial sub­sti­tute for plat­inum-based cat­a­lysts for diesel emis­sion con­trol.

Biog­ra­phy — Johannes Schwank holds a Ph. D. degree in Phys­i­cal Chem­istry from Inns­bruck Uni­ver­si­ty in Aus­tria. He joined the fac­ul­ty at the Uni­ver­si­ty of Michi­gan in 1980 where he rose through the ranks and became Full Pro­fes­sor of Chem­i­cal Engi­neer­ing in 1990. He served as Chair­man of the Chem­i­cal Engi­neer­ing Depart­ment from 1990 – 1995, as Inter­im Direc­tor of the Uni­ver­si­ty of Michi­gan Ener­gy Insti­tute 2011/2012, and as Direc­tor of EMAL (Elec­tron Microbeam Analy­sis Lab­o­ra­to­ry), a cam­pus-wide user facil­i­ty 2013–2015. He is the hold­er of the James and Judith Street Chair in Chem­i­cal Engi­neer­ing and the Direc­tor of REFRESCH, an inter­dis­ci­pli­nary project that deals with food, ener­gy, and water secu­ri­ty in resource–constrained envi­ron­ments.

He serves on mul­ti­ple edi­to­r­i­al boards and indus­tri­al and aca­d­e­m­ic advi­so­ry boards. He has co-found­ed a suc­cess­ful start-up com­pa­ny, Aker­vall Tech­nolo­gies. He is the author of more than 200 ref­er­eed pub­li­ca­tions, and holds 15 patents. His research group is work­ing on a wide range of top­ics, includ­ing nanos­truc­tured mate­ri­als for catal­y­sis, ener­gy stor­age, and gas sens­ing appli­ca­tions; syn­thet­ic fuels; bio­mass con­ver­sion; hydro­gen pro­duc­tion; sol­id oxide fuel cells; auto­mo­tive emis­sion con­trol cat­a­lysts; pho­to­catal­y­sis; and nov­el cat­a­lyst syn­the­sis and char­ac­ter­i­za­tion meth­ods.

Morphological Instability in Topologically Complex, Three-Dimensional Electrocatalytic Nanostructures

Meeting Program — March 2018

Yawei Li — Stu­dent Speak­er

Advi­sor: Joshua Sny­der
Depart­ment of Chem­i­cal and Bio­log­i­cal Engi­neer­ing
Drex­el Uni­ver­si­ty, Philadel­phia, Penn­syl­va­nia 19104
 

Abstract — Deal­loy­ing has shown increas­ing util­i­ty in the field of elec­tro­catal­y­sis as a tool for the syn­the­sis and devel­op­ment of nanoporous mate­ri­als pos­sess­ing high sur­face-to-vol­ume ratios with con­trolled mor­phol­o­gy and com­po­si­tion­al gra­di­ent (core-shell struc­ture). After elec­tro­chem­i­cal deal­loy­ing, the open, bicon­tin­u­ous, three-dimen­sion­al nanoporous nanopar­ti­cle elec­tro­cat­a­lysts exhib­it dra­mat­i­cal­ly enhanced elec­tro­cat­alyt­ic prop­er­ties.

In the devel­op­ment of effi­cient elec­tro­cat­a­lysts for oxy­gen reduc­tion reac­tion (ORR), dura­bil­i­ty is too often ignored in the pur­suit of high­er activ­i­ties. For 3-dimen­sion­al, nanoporous mate­ri­als, in addi­tion to the stan­dard mech­a­nisms of elec­tro­cat­a­lyst degra­da­tion includ­ing Pt dissolution/Ostwald ripen­ing and coalescence/aggregation, new modes of mor­pho­log­i­cal and com­po­si­tion­al evo­lu­tion must be con­sid­ered. Here we use a com­bi­na­tion of in-situ and ex-situ exper­i­men­tal tech­niques to devel­op insight into the struc­tur­al and com­po­si­tion­al evo­lu­tion of nanoporous PtNi nanopar­ti­cles (np-NiPt) formed through the deal­loy­ing of Pt 20 Ni 80 pre­cur­sor nanopar­ti­cles. We demon­strate that sur­face-dif­fu­sion facil­i­tat­ed coars­en­ing, dri­ven by the ten­den­cy to reduce the over­all sur­face free ener­gy of the sys­tem, is the dom­i­nant mech­a­nism of elec­tro­chem­i­cal active sur­face area (ECSA) loss, con­se­quent­ly result­ing in a decrease in activ­i­ty.

With a bet­ter under­stand­ing of the inter­play between nanoporous struc­ture coars­en­ing and tran­si­tion met­al loss, we have devel­oped strat­e­gy to mit­i­gate coars­en­ing and improve oper­a­tional cat­a­lyst sta­bil­i­ty by imped­ing step edge move­ment through the use of for­eign adsor­bates on the
sur­face. We show that par­tial mono­lay­er dec­o­ra­tion of np-NiPt with Ir, pos­sess­ing a sig­nif­i­cant­ly low­er rate of sur­face dif­fu­sion than Pt, acts to pin step edges and results in sig­nif­i­cant enhance­ment in cat­a­lyst dura­bil­i­ty as mea­sured by ECSA and ORR activ­i­ty reten­tion. With this strat­e­gy we will show how more detailed insight into the atom­ic process­es that gov­ern elec­tro­cat­alyt­ic mate­r­i­al insta­bil­i­ty can begin to break the inverse cor­re­la­tion between activ­i­ty and dura­bil­i­ty.

Synthesis of Nanosized Zeolites For Different Catalytic Applications

Meeting Program — March 2018

Manuel Moliner
Manuel Molin­er
Tenured Sci­en­tist, Insti­tu­to de Tec­nología Quími­ca (UPV-CSIC)
Uni­ver­si­dad Politéc­ni­ca de Valen­cia,
Con­se­jo Supe­ri­or de Inves­ti­ga­ciones Cien­tí­fi­cas

 

Abstract — On the one hand, the prepa­ra­tion of dif­fer­ent zeo­lites, i.e. Beta and ZSM-5, in their nano­sized forms with con­trolled Si/Al molar ratios (~15–30), high sol­id yields (above 90%), and homo­ge­neous crys­tal sizes (~10–25 nm), has been achieved by using sim­ple bifunc­tion­al alkyl-sub­sti­tut­ed mono-cation­ic cyclic ammo­ni­um cations as OSDA mol­e­cules [1]. These OSDAs com­bine a cyclic part and a short alkyl-chain group (pref­er­en­tial­ly C4) and, depend­ing on the size and nature of the cyclic frag­ment, the crys­tal­liza­tion of dif­fer­ent zeo­lites can be con­trolled. The cat­alyt­ic prop­er­ties of the achieved nano­sized zeolitic mate­ri­als have been eval­u­at­ed for the methanol-to-olefins and olefin oligomer­iza­tion reac­tions [1].
On the oth­er hand, the effi­cient syn­the­sis of the small-pore CHA and AEI zeo­lites with nano­sized crys­tals (20—50 nm) has also been obtained fol­low­ing zeo­lite-to-zeo­lite trans­for­ma­tion pro­ce­dures, where high-sil­i­ca FAU mate­ri­als have been used as sil­i­con and alu­minum pre­cur­sors [2]. The nano­sized small pore zeo­lites have been eval­u­at­ed for the methanol-to-olefin reac­tion, observ­ing that their cat­a­lyst life­times are remark­ably longer than the cat­a­lyst life­times observed for con­ven­tion­al small pore zeo­lites. In addi­tion, the selec­tiv­i­ty towards dif­fer­ent light olefins, i.e. propy­lene and/or eth­yl­ene, can be max­i­mized depend­ing on the crys­talline struc­ture of the nano­sized zeo­lites.

Ref­er­ences:

  1. (a) E.M. Gal­lego et al., Chem. Sci., 2017, 8, 8138.; (b) M.R. Díaz-Rey et al., ACS Catal., 2017, 7, 6170.
  2. N. Martín et al., Chem. Com­mun., 2016, 52, 6072.

Biog­ra­phy — Manuel Molin­er obtained his B.S. degree in Chem­i­cal Engi­neer­ing at the Uni­ver­si­ty of Valen­cia (Spain) in 2003, and com­plet­ed his Ph.D. at the Poly­tech­nic Uni­ver­si­ty of Valen­cia (UPV, Spain), in Chem­istry, under the guid­ance of Prof. Aveli­no Cor­ma in 2008. After­ward, he com­plet­ed a two-year post­doc (2008–2010) with Prof. Mark Davis at the Cal­i­for­nia Insti­tute of Tech­nol­o­gy (Cal­tech, USA).
He is a Tenured Sci­en­tist of the Span­ish Nation­al Research Coun­cil (CSIC) since 2014, where his research lies at the inter­face of het­ero­ge­neous catal­y­sis and mate­ri­als design.
Manuel Molin­er has pub­lished 70 papers in inter­na­tion­al jour­nals, and is co-inven­tor of 24 inter­na­tion­al patents (14 trans­ferred to indus­try). He has received dif­fer­ent nation­al and inter­na­tion­al awards, as the “EFCATS The­sis Award” to the best Ph.D. The­sis in Europe in 2007–2009, the “TR-35 Spain 2011” award­ed by MIT to young tal­ents in Spain under-35, or the “FISOCAT 2014” to young sci­en­tists under 40 in Latin Amer­i­ca.

Remembering Robert K. Grasselli: Reflections on Three Decades of Collaboration on Complex Oxides for Selective Oxidation

Meeting Program — February 2018

Doug Buttrey
Dou­glas J. But­trey
Pro­fes­sor of Chem­i­cal and Bio­mol­e­c­u­lar Engi­neer­ing,
Uni­ver­si­ty of Delaware

 

Robert GrasselliAbstract — In this pre­sen­ta­tion, I will pay trib­ute to the late Robert K. Gras­sel­li, a tru­ly extra­or­di­nary sci­en­tist who served as a ded­i­cat­ed men­tor to many indus­tri­al sci­en­tists and engi­neers, as well as a num­ber of aca­d­e­mics, such as myself. The pri­ma­ry focus of his research was on improv­ing gen­er­a­tions of com­plex oxide cat­a­lysts for pro­duc­tion of acry­loni­trile by ammox­i­da­tion of propy­lene through much of his career, and of propane in the lat­er years. The Sohio chem­i­cal catal­y­sis group, which Gras­sel­li lead for many years, suc­ceed­ed in devel­op­ing and steadi­ly improv­ing the rev­o­lu­tion­ary SOHIO process for using mul­ti­com­po­nent bis­muth molyb­dates to pro­duce a 50-fold increase in pro­duc­tion of acry­loni­trile, a plat­form chem­i­cal used for mak­ing syn­thet­ic fibers and ABS plas­tics. He became Senior Sci­ence Fel­low at the Sohio Com­pa­ny in Cleve­land, and end­ed his career there in 1985 after about 25 years of ser­vice. This was fol­lowed by 3 years as Direc­tor of the Chem­istry Divi­sion at the Office of Naval Research. From there, he moved to Mobil Research and Devel­op­ment Cor­po­ra­tion in Prince­ton, where he worked until 1995.

Robert Gras­sel­li was induct­ed into the US Nation­al Acad­e­my of Engi­neer­ing in 1995. In 1996, the Sohio acry­loni­trile process was rec­og­nized as the 11th Nation­al His­toric Chem­i­cal Land­mark by the ACS. For this work, Gras­sel­li was admit­ted to the US Engi­neer­ing and Sci­ence Hall of Fame.

Also in 1996, Gras­sel­li became an adjunct pro­fes­sor in the Cen­ter for Cat­alyt­ic Sci­ence and Tech­nol­o­gy at the Uni­ver­si­ty of Delaware; simul­ta­ne­ous­ly, he was appoint­ed as Guest Pro­fes­sor of Phys­i­cal and Cat­alyt­ic Chem­istry at the Uni­ver­si­ty of Munich. He devel­oped a num­ber of col­lab­o­ra­tions through­out the world with William A. God­dard (Cal­Tech), Sir John Meurig Thomas (Cam­bridge), Arne Ander­s­son (Lund), Johannes Lercher (Vien­na and Tri­este), Fer­ruc­cio Tri­firo (Bologne) and many oth­ers, includ­ing myself. I will dis­cuss our col­lab­o­ra­tive work start­ing with the bis­muth molyb­dates begin­ning in 1984 and, from 2002 onward, on the Mo-V-Nb-Te-O bronze “M1” cat­a­lyst for ammox­i­da­tion of propane to acry­loni­trile.

Biog­ra­phy — Dou­glas J. But­trey is a pro­fes­sor of Chem­i­cal and Bio­mol­e­c­u­lar Engi­neer­ing in the Cen­ter for Cat­alyt­ic Sci­ence and Tech­nol­o­gy, with an affil­i­at­ed appoint­ment in Mate­ri­als Sci­ence and Engi­neer­ing, at the Uni­ver­si­ty of Delaware. He received his PhD degree from the Pur­due Uni­ver­si­ty in 1984, and sub­se­quent­ly held the Sohio Post­doc­tor­al Research Fel­low­ship in the Depart­ment of Phys­i­cal Chem­istry at Cam­bridge Uni­ver­si­ty in 1984–85. He was a vis­it­ing assis­tant pro­fes­sor at Pur­due Uni­ver­si­ty with a 3-way joint appoint­ment in the Depart­ment of Chem­istry, Depart­ment of Physics and Astron­o­my, and the School of Mate­ri­als Sci­ence and Engi­neer­ing from 1986–87, before mov­ing to the Uni­ver­si­ty of Delaware. He is the co-author of 100 jour­nal pub­li­ca­tions with over 5,700 cita­tions.

Improved methane reforming activity and coking resistance of self-regenerating Ni catalyst by Atomic Layer Deposition

Meeting Program — February 2018

Chao Lin — Stu­dent Speak­er

Advi­sor: Ray­mond J. Gorte
Depart­ment of Chem­i­cal and Bio­mol­e­c­u­lar Engi­neer­ing
Uni­ver­si­ty of Penn­syl­va­nia
 

Abstract — Per­ovskite-sup­port­ed Ni cat­a­lysts were pre­pared by Atom­ic Lay­er Depo­si­tion for use in CO2 and steam reform­ing of methane. Thin films of CaTiO3 were grown on MgAl2O4 and used as the sup­port. These cat­a­lysts were found to be self-regen­er­at­ing fol­low­ing redox cycling. Activ­i­ties for the ALD-pre­pared cat­a­lysts were high­er than that observed on Ni/MgAl2O4 in both steam reform­ing and dry reform­ing. More impor­tant­ly, the per­ovskite-sup­port­ed cat­a­lysts showed min­i­mal cok­ing, even upon expo­sure to dry methane at high tem­per­a­tures.

Siliceous Zeolite-supported Palladium Catalysts for Methane Oxidation

Meeting Program — January 2018

Jing Lu
Jing Lu
Staff Sci­en­tist at Clean Air Divi­sion
John­son Matthey Inc.

 

Abstract — Cat­alyt­ic oxi­da­tion of methane in the pres­ence of excess of oxy­gen is of great inter­est as a prac­ti­cal tech­nol­o­gy to reduce methane emis­sions from com­pressed nat­ur­al gas vehi­cles, engines, and tur­bines. Typ­i­cal com­mer­cial methane oxi­da­tion cat­a­lysts are alu­mi­na-sup­port­ed pal­la­di­um cat­a­lysts. When oper­at­ed at low tem­per­a­tures, these cat­a­lysts exhib­it rapid deac­ti­va­tions on stream due to water inhi­bi­tion. In addi­tion, these Pd-cat­a­lysts are sen­si­tive to sul­fur poi­son­ing, even with the pres­ence of a trace amount (≤ 1 ppm) of SO2 in the feed. Among oth­er oxide mate­ri­als, zeo­lites were also inves­ti­gat­ed as a poten­tial sup­port for pal­la­di­um – such as the effects of frame­works and exchange or impreg­na­tion meth­ods – but no sig­nif­i­cant ben­e­fits were dis­cov­ered in the past com­par­ing to con­ven­tion­al alu­mi­na-based cat­a­lysts. Here, we demon­strate the appli­ca­tion of siliceous zeo­lites (i.e. SiO2-to-Al2O3 ratio (SAR) >1200) as Pd-sup­port, the result­ing cat­a­lysts exhib­it sig­nif­i­cant­ly improved activ­i­ty and on-stream dura­bil­i­ty at low tem­per­a­tures, and are able to be regen­er­at­ed from sul­fur poi­son­ing under real­is­tic oper­at­ing con­di­tions.

Biog­ra­phy — Jing Lu received his B.S. degree in Chem­i­cal Engi­neer­ing from Uni­ver­si­ty of Cal­i­for­nia, San­ta Bar­bara. He joined John­son Matthey in 2013 after earn­ing a Ph.D. from Uni­ver­si­ty of Cal­i­for­nia, Davis where he worked with Prof. Bruce Gates. Jing is cur­rent­ly a Staff Sci­en­tist lead­ing the devel­op­ments of selec­tive cat­alyt­ic reduc­tion, ammo­nia slip con­trol and methane oxi­da­tion cat­a­lysts for diesel and nat­ur­al gas aftertreat­ment. He is an inven­tor of sev­er­al patents and author of 19 jour­nal arti­cles.

Kinetic Peculiarities of Cu-Zeolite SCR Catalysts, and Their Practical Implications

Meeting Program — November 2017

Aleksey Yezerets
Alek­sey Yez­erets
Direc­tor of Advanced Chem­i­cal Sys­tems & Inte­gra­tion
Cum­mins Inc.

 

Abstract — Cu-Zeo­lite SCR cat­a­lysts have emerged in the recent years as the lead­ing tech­nol­o­gy for meet­ing the chal­lenge of NOx reduc­tion in diesel exhaust. Despite their excel­lent per­for­mance and sta­bil­i­ty char­ac­ter­is­tics, inte­grat­ing this class of cat­a­lysts into an effec­tive and durable exhaust aftertreat­ment sys­tem has proved non-triv­ial. Such sys­tems must be capa­ble of oper­at­ing over a broad range of tran­sient con­di­tions, sur­vive a vari­ety of nom­i­nal and off-nom­i­nal aging expo­sures, and sus­tain their activ­i­ty over many years of active duty. This requires a detailed under­stand­ing of the reac­tion mech­a­nism and deac­ti­va­tion path­ways, and the abil­i­ty to trans­late those into reac­tion engi­neer­ing guid­ance to sys­tem design, feed­back con­trol algo­rithms, and on-board diag­nos­tics. In this pre­sen­ta­tion, we will share exam­ples from our recent find­ings relat­ed to the con­trol­ling regimes of oper­a­tion and to the deac­ti­va­tion mech­a­nisms of Cu-Zeo­lite cat­a­lysts – at the lev­el of cat­a­lyst mate­r­i­al, chem­i­cal func­tions, and over­all emis­sion reduc­tion per­for­mance in the con­text of a sys­tem which con­tains mul­ti­ple cat­alyt­ic ele­ments. We will fur­ther dis­cuss the advance­ments in the abil­i­ty to mod­el the behav­iors of healthy and deac­ti­vat­ed cat­a­lysts, and the respec­tive impli­ca­tions to sys­tem opti­miza­tion and con­trol.

Biog­ra­phy — As Direc­tor of Advanced Chem­i­cal Sys­tems & Inte­gra­tion with Cor­po­rate R&T Divi­sion of Cum­mins Inc., the world’s largest inde­pen­dent man­u­fac­tur­er of diesel engines and relat­ed equip­ment, Dr. Alek­sey (Alex) Yez­erets leads a team of exper­i­men­tal­ists and mod­el­ers respon­si­ble for devel­op­ing an under­stand­ing of the per­for­mance and deac­ti­va­tion of bat­ter­ies, cat­a­lysts, and sen­sors, and for pro­vid­ing guid­ance and sup­port to elec­tri­fied and low-emis­sion prod­ucts at all stages of their life­cy­cles. He also coor­di­nates a port­fo­lio of col­lab­o­ra­tive research pro­grams with indus­tri­al part­ners, Nation­al Labs, and uni­ver­si­ties. He has authored or co-authored 35 patents and 80 peer-reviewed pub­li­ca­tions, with over 2500 total cita­tions. Alex main­tains cur­ren­cy in his field by an active engage­ment in pro­fes­sion­al, edi­to­r­i­al, and grad­u­ate edu­ca­tion activ­i­ties. His tech­ni­cal con­tri­bu­tions have been rec­og­nized by awards from the Catal­y­sis Club of Chica­go, R&D100, ACS, AIChE and SAE, as well as by two Cum­mins Julius Perr awards for inno­va­tion. Alex has been elect­ed an SAE Fel­low.