Zeolite Encapsulated Metal Nanoparticles for Selective Tandem Catalysis

Feb­ru­ary 2019

Bingjun Xu, Uni­ver­si­ty of Delaware

Abstract: Het­ero­ge­neous catal­y­sis is one of the pil­lars of the ener­gy and
chem­i­cal indus­tries, and a cen­tral sci­ence in dri­ving the
accel­er­at­ing tran­si­tion to a car­bon neu­tral future.
Under­stand­ing cat­alyt­ic process­es medi­at­ed by sol­id sur­faces
on the mol­e­c­u­lar lev­el holds the key to cat­a­lyst design, but is
chal­leng­ing due to the com­plex­i­ty of the local envi­ron­ment in
which chem­i­cal trans­for­ma­tions occur. In this lec­ture,
encap­su­la­tion of met­al nanopar­ti­cles in zeo­lite crys­tals as an
effec­tive cat­a­lyst archi­tec­ture to medi­ate selec­tive tan­dem
upgrad­ing of bio­mass derived feed­stocks is dis­cussed in the
con­text of two case stud­ies. The sequence to which sub­strates
are exposed to dif­fer­ent active sites and the dis­tri­b­u­tion of
met­al and acid sites in zeo­lite crys­tals are shown to play deci­sive roles in deter­min­ing selec­tiv­i­ty
and sta­bil­i­ty of cat­a­lysts.

Engineering Industrial Catalysts: A Personal Journey

Jan­u­ary 2019
Dr. Car­mo Pereira
DuPont Clean Tech­nolo­gies

Abstract: Indus­tri­al reac­tors enable chem­i­cal trans­for­ma­tions that may upgrade the qual­i­ty of the feed, pro­duce chem­i­cals, and/or reduce process pol­lu­tants. The cat­a­lysts in these reac­tors are engi­neered to obtain the required (steady state) through­put of prod­uct over a cer­tain time. In addi­tion to through­put, there are addi­tion­al com­mer­cial­iza­tion con­straints that involve cost, uptime, emis­sions, and project tim­ing. The prop­er design of the cat­a­lyst and reac­tor often is key to the suc­cess­ful deploy­ment of the process.
In addi­tion to iden­ti­fy­ing the active site and the reac­tion mech­a­nism, addi­tion­al appli­ca­tion devel­op­ment work is required to com­mer­cial­ize a cat­a­lyst. The active site must func­tion with­in a range of oper­at­ing con­di­tions and in the pres­ence of impu­ri­ties that may impact activ­i­ty and selec­tiv­i­ty. Reac­tor pres­sure drop con­straints can dic­tate the size and struc­ture of the cat­a­lyst. The avail­abil­i­ty of active sites in a pel­let is max­i­mized by opti­miz­ing its size, shape and pore struc­ture to min­i­mize heat and mass trans­port lim­i­ta­tions. The num­ber of active sites in a cat­a­lyst may dra­mat­i­cal­ly decrease with time due to poi­son­ing, mask­ing, sin­ter­ing, or pore block­age. An under­stand­ing of the deac­ti­va­tion mech­a­nism under oper­at­ing con­di­tions pro­vides a basis for the reac­tor oper­at­ing strat­e­gy and for siz­ing reac­tors that have a war­rant­ed life. A process flow­sheet con­tain­ing a use­ful reac­tor mod­el may be sub­se­quent­ly val­ue-engi­neered to cost-effec­tive­ly meet the pro­cess­ing objec­tive.
This talk will present sev­er­al vignettes from the author’s expe­ri­ence where chem­i­cal reac­tion engi­neer­ing method­olo­gies were used to engi­neer indus­tri­al cat­a­lysts used in petro­chem­i­cal, chem­i­cal, and envi­ron­men­tal appli­ca­tions.

How can the modern scanning transmission electron microscope aid catalysis science?

Novem­ber 2018
Prof. Eric A. Stach
Uni­ver­si­ty of Penn­syl­va­nia
E-mail: stach@​seas.​upenn.​edu, Web:https://stachgroup.seas.upenn.edu/
Abstract: The past decade or so have seen a num­ber of tech­no­log­i­cal advances in the field of trans­mis­sion elec­tron microscopy that have dra­mat­i­cal­ly enhanced both the util­i­ty and uti­liza­tion of the instru­ment in the field of het­ero­ge­neous catal­y­sis. These include aber­ra­tion cor­rec­tion, enhanced detec­tors and improve­ments in sim­u­la­tion and analy­sis soft­ware. In this pre­sen­ta­tion, I will present sev­er­al spe­cif­ic exam­ples from both my own research and from oth­ers in the field to pro­vide a gen­er­al overview of the state of the art. In spe­cif­ic, I will describe the lim­its of spa­tial, spec­tro­scop­ic and tem­po­ral ener­gy res­o­lu­tion, and demon­strate how one can per­form both real time and operan­do mea­sure­ments do char­ac­ter­ize the inter­re­la­tion­ships between cat­a­lyst struc­ture and cat­a­lyst func­tion. Through the pre­sen­ta­tion, I will empha­size how these tech­niques are being imple­ment­ed at the Singh Cen­ter for Nan­otech­nol­o­gy at the Uni­ver­si­ty of Penn­syl­va­nia and how they are thus acces­si­ble to mem­bers of the Cat­a­lyst Club of Philadel­phia.

Ultra-Deep Diesel Hydrodesulfurization Catalysis and Process: A Tale of Two Sites

Octo­ber 2018 — F.G. Cia­pet­ta Award Lec­ture

Dr. Teh C. Ho
Hydro­car­bon Con­ver­sion Tech­nolo­gies
E-mail: , Web:
Abstract: Hydrodesul­fu­r­iza­tion cat­a­lysts have two types of active sites for hydro­gena­tion and hydrogenol­y­sis reac­tions. While hydro­gena­tion sites are more active for desul­fu­r­iz­ing refrac­to­ry sul­fur species, they are more vul­ner­a­ble to organon­i­tro­gen inhi­bi­tion than hydrogenol­y­sis sites. In con­trast, hydrogenol­y­sis sites are less active for desul­fu­r­iz­ing refrac­to­ry sul­fur species but are more resis­tant to organon­i­tro­gen inhi­bi­tion. This dichoto­my is exploit­ed to devel­op an ultra-deep hydrodesul­fu­r­iza­tion stacked-bed reac­tor com­pris­ing two cat­a­lysts of dif­fer­ent char­ac­ter­is­tics. The per­for­mance of this cat­a­lyst sys­tem can be supe­ri­or or infe­ri­or to that of either cat­a­lyst alone. A the­o­ry is devel­oped to pre­dict the opti­mum stack­ing con­fig­u­ra­tion for max­i­mum syn­er­gies between the two cat­a­lysts. The best con­fig­u­ra­tion pro­vides the pre­cise envi­ron­ment for the cat­a­lysts to reach their full poten­tials, result­ing in the small­est reac­tor vol­ume and max­i­mum ener­gy sav­ing. Mod­el pre­dic­tions are con­sis­tent with exper­i­men­tal results. A selec­tiv­i­ty-activ­i­ty dia­gram is devel­oped for guid­ing the devel­op­ment of stacked-bed cat­a­lyst sys­tems.

Catalysis by Pincer-Iridium Complexes. Breaking C-H Bonds, Making C-C Bonds, and Various Combinations Thereof

Sep­tem­ber 2018

Pro­fes­sor Alan S. Gold­man
Depart­ment of Chem­istry and Chem­i­cal Biol­o­gy, Rut­gers — The State Uni­ver­si­ty of New Jer­sey
E-mail: alan.​goldman@​rutgers.​edu, Web: http://​ccb​.rut​gers​.edu/​g​o​l​d​m​a​n​-​a​lan
Abstract: Irid­i­um com­plex­es have played a lead­ing role in the organometal­lic chem­istry of
alka­nes and unre­ac­tive C-H bonds since the incep­tion of the field 30 years ago. We have found
that “PCP”-pincer-ligated irid­i­um com­plex­es are par­tic­u­lar­ly effec­tive for the dehy­dro­gena­tion of
alka­nes and have incor­po­rat­ed this reac­tion into tan­dem sys­tems for sev­er­al cat­alyt­ic
trans­for­ma­tions based on dehy­dro­gena­tion. A close­ly relat­ed class of reac­tions that we are
explor­ing is dehy­dro­gena­tive cou­pling. More recent­ly we have turned atten­tion to irid­i­um
Phe­box com­plex­es. Although the (PCP)Ir and (Phebox)Ir units are for­mal­ly iso­elec­tron­ic, the
for­mer oper­ates via C-H acti­va­tion by Ir(I) while the lat­ter effects dehy­dro­gena­tion via Ir(III) (as
an acetate com­plex) and pos­si­bly Ir(V) inter­me­di­ates. Such a high-oxi­da­tion-state cat­alyt­ic cycle
offers advan­tages for many poten­tial appli­ca­tions of dehy­dro­gena­tion. In par­al­lel, how­ev­er, we
find that the low-oxi­da­tion-state (+I) chem­istry of (Phebox)Ir offers its own nov­el hydro­car­bon
chem­istry.
1. Gao, Y.; Guan, C.; Zhou, M.; Kumar, A.; Emge, T. J.; Wright, A. M.; Gold­berg, K. I.; Krogh-Jes­persen, K.; Gold­man, A. S. J. Am. Chem. Soc. 2017,
139, 6338–6350.
2. Wilk­low-Mar­nell, M.; Li, B.; Zhou, T.; Krogh-Jes­persen, K.; Bren­nes­sel, W. W.; Emge, T. J.; Gold­man, A. S.; Jones, W. D. J. Am. Chem. Soc. 2017,
139, 8977–8989.
3. Gold­berg, K. I.; Gold­man, A. S. Acc. Chem. Res. 2017, 50, 620–626.
4. Kumar, A.; Bhat­ti, T. M.; Gold­man, A. S. Chem. Rev. 2017, 117, 12357–12384.
5. Gao, Y.; Emge, T. J.; Krogh-Jes­persen, K.; Gold­man, A. S. J. Am. Chem. Soc. 2018, 140, 2260–2264.

Renewable Isoprene By Sequential Hydrogenation of Itaconic Acid and Dehydra-Decyclization of 3-Methyl-Tetrahydrofuran

2018 Spring Symposium

Omar Abdel­rah­man, Post-Doc, Paul Dauen­hauer Group, Depart­ment of Chem­i­cal Engi­neer­ing & Mate­r­i­al Sci­ence, Uni­ver­si­ty of Min­neso­ta, 421 Wash­ing­ton Ave. SE, Min­neapo­lis, MN 55455

Abstract — The cat­alyt­ic con­ver­sion of bio­mass-derived feed­stocks to val­ue added chem­i­cals is an impor­tant chal­lenge to alle­vi­ate the depen­dence on petro­le­um-based resources. To accom­plish this, the inher­ent­ly high oxy­gen con­tent of bio­mass com­pounds, such as that of lig­no­cel­lu­losic bio­mass, requires sig­nif­i­cant reduc­tion via hydrodeoxy­gena­tion strate­gies. The unsat­u­rat­ed car­boxylic acid ita­con­ic acid (IA) can be pro­duced from bio­mass via fer­men­ta­tion path­ways, for exam­ple. A path­way of inter­est is the con­ver­sion of IA to iso­prene, facil­i­tat­ing the renew­able pro­duc­tion of an indus­tri­al­ly rel­e­vant diolefin. IA can be suc­ces­sive­ly hydro­genat­ed to yield 3-methyl tetrahy­dro­fu­ran (3-MTHF), in a one-pot cas­cade reac­tion, where a Pd-Re bimetal­lic cat­a­lyst results in an 80% yield to 3-MTHF. The 3-MTHF can then be con­vert­ed to iso­prene, and oth­er pen­ta­di­enes, through an acid cat­alyzed vapor-phase dehy­dra-decy­cliza­tion. Mul­ti­ple sol­id acid cat­a­lysts, includ­ing alu­mi­nosil­i­cates, met­al oxides and phos­pho­rous mod­i­fied zeo­lites, were screened for the dehy­dra-decy­cliza­tion step. A new class of cat­alyt­ic mate­ri­als, all sil­i­con
phos­pho­rous con­tain­ing zeo­lites, were found to be the most selec­tive (70% iso­prene and 20% pen­ta­di­enes), where the major side reac­tion involved is a retro-prins con­den­sa­tion of 3-MTHF to butane and formalde­hyde. Through kinet­ic stud­ies, an inves­ti­ga­tion into the effect of Brøn­st­ed acid strength, pore size and oper­at­ing con­di­tions on the selec­tiv­i­ty to iso­prene are dis­cussed. The prospect of apply­ing this dehy­dra-decy­cliza­tion strat­e­gy to oth­er sat­u­rat­ed cyclic ethers will also be dis­cussed, which enables the pro­duc­tion of oth­er diolefin mol­e­cules of inter­est such as buta­di­ene and lin­ear pen­ta­di­enes.

Ref­er­ences:
[1] Abdel­rah­man, O. A.; Park, D. S.; Vin­ter, K. P.; Span­jers, C. S.; Ren, L.; Cho, H. J.; Zhang, K.; Fan, W.; Tsap­at­sis, M.; Dauen­hauer, P. J. ACS Catal. 2017, 7, 1428–1431.

Using Water as a Co-catalyst in Heterogeneous Catalysis to Improve Activity and Selectivity

2018 Spring Symposium

Lars C. Grabow, Depart­ment of Chem­i­cal and Bio­mol­e­c­u­lar Engi­neer­ing, Uni­ver­si­ty of Hous­ton, Hous­ton, TX 77204–4004, USA

Abstract — “What hap­pens when you add water?” is pos­si­bly the most fre­quent­ly asked ques­tion after pre­sen­ta­tions in het­ero­ge­neous catal­y­sis. In this talk, I will demon­strate that this ques­tion is indeed para­mount and that the pres­ence of even minute amounts of water can dras­ti­cal­ly change reac­tion rates and prod­uct selec­tiv­i­ties. Exam­ples include water-medi­at­ed pro­ton hop­ping across a met­al-oxide sur­face, oxi­da­tion of car­bon monox­ide at the gold/titania inter­face, and hydrodeoxy­gena­tion of phe­no­lic com­pounds over tita­nia sup­port­ed ruthe­ni­um cat­a­lysts. Togeth­er, these exam­ples demon­strate that water can act as co-cat­a­lyst in a vari­ety of cat­alyt­ic reac­tions and by vary­ing the amount of water it may be pos­si­ble to tune reac­tion rates and prod­uct selec­tiv­i­ty.