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.