Kinetics and Mechanisms of C-C Forming and C-O Cleavage Reactions of Interests in Bio-oil Upgrading

Meeting Program — September 2013

 
Daniel E. Resas­co
Uni­ver­si­ty of Okla­homa
Nor­man, OK

 
Abstract — Bio-oil pro­duced by fast pyrol­y­sis of lig­no­cel­lu­losic bio­mass has attract­ed con­sid­er­able atten­tion as an inter­me­di­ate liq­uid prod­uct towards the pro­duc­tion of fuels. How­ev­er its chem­i­cal insta­bil­i­ty, high vis­cos­i­ty, and cor­ro­sive­ness lim­it their process­abil­i­ty and stor­age. One of the great­est chal­lenges in the upgrad­ing of bio-oil is the accel­er­at­ed degra­da­tion that occurs when the con­densed liq­uid is sub­se­quent­ly heat­ed for frac­tion­a­tion or oth­er pro­cess­ing. Cat­alyt­ic upgrad­ing is an attrac­tive strat­e­gy that can be used to opti­mize car­bon effi­cien­cy and min­i­mize hydro­gen usage. Impor­tant reac­tions for this upgrad­ing include:

  • For­ma­tion of C-C bonds to extend the car­bon back­bone of short oxy­genates to the desired gasoline/diesel range via aldol con­den­sa­tion and ketoniza­tion in aque­ous phase
  • Incor­po­ra­tion of short car­bon frag­ments (C1-C3) into the aro­mat­ic ring of phe­no­lic com­pounds via alky­la­tion in bipha­sic sys­tems
  • Deoxy­gena­tion of the result­ing prod­ucts to mono­func­tion­al com­pounds or hydro­car­bons in the liq­uid phase.

We have inves­ti­gat­ed the kinet­ics and reac­tion mech­a­nisms of these reac­tions on dif­fer­ent cat­a­lysts, includ­ing met­als sup­port­ed on reducible oxides (e.g. Ru/TiO2); acidic cat­a­lysts (HY, H-beta zeo­lites), sup­port­ed met­al cat­a­lysts (Cu, Ni, Ru, Pd sup­port­ed on car­bon nan­otubes) and amphiphilic nanopar­ti­cle cat­a­lysts that are able sta­bi­lize water/oil emul­sions and to con­duct reac­tions at the liquid/liquid inter­face to ben­e­fit from the dif­fer­ences in sol­u­bil­i­ty exhib­it­ed by the reac­tants (bio-oil) and prod­ucts (bio-fuels) and achieve con­tin­u­ous reaction/separation.
 
Ref­er­ences

  1. Improv­ing car­bon reten­tion in bio­mass con­ver­sion by alky­la­tion …” Appl. Catal. A 447, 14, 2012.
  2. Aque­ous Phase Ketoniza­tion of Acetic Acid over Ru/TiO2/Carbon Cat­a­lysts” J. Catal. 295, 169, 2012.
  3. Hydropho­bic zeo­lites for bio­fu­el upgrad­ing at the liq­uid-liq­uid inter­face … JACS134, 8570, 2012.
  4. What Should We Demand from the Cat­a­lysts Respon­si­ble for Upgrad­ing Bio­mass?” J. Phys. Chem. Lett., 2, 2294, 2011.
  5. Selec­tive Con­ver­sion of Fur­fur­al to Methyl­fu­ran over Ni-Fe Cat­a­lysts,” J. Catal. 284, 90, 2011.
  6. Bifunc­tion­al transalky­la­tion and hydrodeoxy­gena­tion of anisole over Pt/HBeta,” J. Catal. 281, 21, 2011.
  7. Con­ver­sion of fur­fur­al and 2-methylpen­tanal on Pd–Cu cat­a­lysts” J. Catal. 280, 17, 2011.
  8. catalys isclubphi l ly​.org

  9. Kinet­ics and mech­a­nism of hydro­gena­tion of fur­fur­al on Cu cat­a­lysts,” J. Catal. 277, 1, 2011.
  10. Role of transalky­la­tion in the con­ver­sion of anisole over HZSM-5,” Appl. Catal. A, 379, 172, 2010.
  11. Sol­id Nanopar­ti­cles that Cat­alyze Bio­fu­el Upgrade at the Water-Oil Inter­face, ” Sci­ence, 327, 68, 2010.

 
Daniel_ResascoBiog­ra­phy — Daniel E. Resas­co is a Pro­fes­sor of Chem­i­cal, Bio­log­i­cal, and Mate­ri­als Engi­neer­ing at the Uni­ver­si­ty of Okla­homa. He holds the D. Bourne endowed Chair. He received his PhD from Yale Uni­ver­si­ty in 1983. He is author of more than 200 pub­li­ca­tions and 35 indus­tri­al patents in the areas of het­ero­ge­neous catal­y­sis and car­bon nan­otubes and has received more than 8,000 cita­tions. He has been a Pres­i­den­tial Pro­fes­sor, S. Wil­son Pro­fes­sor, and in the last few years he was award­ed the Okla­homa Chemist of the Year award by the Amer­i­can Chem­i­cal Soci­ety, the Yale Sci­ence and Engi­neer­ing Asso­ci­a­tion award, and the Regents Award for Supe­ri­or Research. He is the founder of South­West Nan­otech­nolo­gies, a com­mer­cial car­bon nan­otube pro­duc­er that oper­ates in Nor­man, OK. He has been Edi­tor of the Jour­nal of Catal­y­sis, and has been a mem­ber of the edi­to­r­i­al board of Applied Catal­y­sis and Jour­nal of Catal­y­sis.

In Situ Spectroscopic Studies of Metal Oxide Electrodes During Water Oxidation

Meeting Program — April 2013

 
John Kitchin
Depart­ment of Chem­i­cal Engi­neer­ing,
Carnegie Mel­lon Uni­ver­si­ty

 
Abstract — Elec­tro­chem­i­cal water split­ting may be in inte­gral part of future ener­gy stor­age strate­gies by enabling ener­gy stor­age in chem­i­cal bonds. One of the pri­ma­ry sources of inef­fi­cien­cy in the water split­ting reac­tion is the oxy­gen evo­lu­tion reac­tion, which has high reac­tion bar­ri­ers that require addi­tion­al applied elec­tric poten­tial to dri­ve the reac­tions at prac­ti­cal rates. The most active elec­trode mate­ri­als in acid elec­trolytes include ruthe­ni­um and irid­i­um oxides, which are expen­sive but nec­es­sary for sta­bil­i­ty. In alka­line envi­ron­ments, many base met­al oxides become sta­ble, although they are still less active than Ru and Ir oxides. It has been known that small amounts of Fe can pro­mote the elec­tro­chem­i­cal activ­i­ty of nick­el oxides, mak­ing it almost as active as cobalt oxide. We have inves­ti­gat­ed the mech­a­nisms behind the pro­mo­tion using in situ Raman and syn­chro­tron spec­tro­scopies as well as ex situ char­ac­ter­i­za­tion tech­niques. Inter­est­ing­ly, we found the elec­trode changes under oxy­gen evo­lu­tion con­di­tions, turn­ing from an oxide to an oxy­hy­drox­ide phase. Fur­ther­more, the com­po­si­tion of the elec­trolyte has a sig­nif­i­cant effect on the oxy­gen evo­lu­tion activ­i­ty. We will dis­cuss these results and their impli­ca­tions in find­ing bet­ter oxy­gen evo­lu­tion elec­tro­cat­a­lysts.
 

John Kitchin

John Kitchin

Biog­ra­phy — John Kitchin com­plet­ed his B.S. in Chem­istry at North Car­oli­na State Uni­ver­si­ty. He com­plet­ed a M.S. in Mate­ri­als Sci­ence and a PhD in Chem­i­cal Engi­neer­ing at the Uni­ver­si­ty of Delaware in 2004 under the advise­ment of Dr. Jing­guang Chen and Dr. Mark Barteau. He received an Alexan­der von Hum­boldt post­doc­tor­al fel­low­ship and lived in Berlin, Ger­many for 1 ½ years study­ing alloy seg­re­ga­tion with Karsten Reuter and Matthias Schef­fler in the The­o­ry Depart­ment at the Fritz Haber Insti­tut. Pro­fes­sor Kitchin began a tenure-track fac­ul­ty posi­tion in the Chem­i­cal Engi­neer­ing Depart­ment at Carnegie Mel­lon Uni­ver­si­ty in Jan­u­ary of 2006. He is cur­rent­ly an Asso­ciate Pro­fes­sor. At CMU, Pro­fes­sor Kitchin is active in a major research effort with­in the Nation­al Ener­gy Tech­nol­o­gy Lab­o­ra­to­ry Region­al Uni­ver­si­ty Alliance in CO2 cap­ture, chem­i­cal loop­ing and super­al­loy oxi­da­tion. Pro­fes­sor Kitchin also uses com­pu­ta­tion­al meth­ods to study adsor­bate-adsor­bate inter­ac­tions on tran­si­tion met­al sur­faces for appli­ca­tions in catal­y­sis. He was award­ed a DOE Ear­ly Career award in 2010 to inves­ti­gate mul­ti­func­tion­al oxide elec­tro­cat­a­lysts for the oxy­gen evo­lu­tion reac­tion in water split­ting using exper­i­men­tal and com­pu­ta­tion­al meth­ods. He received a Pres­i­den­tial Ear­ly Career Award for Sci­en­tists and Engi­neers in 2011.
 
Recent Pub­li­ca­tions
  1. Sne­ha A. Akhade and John R. Kitchin*, “Effects of strain, d-band fill­ing and oxi­da­tion state on the sur­face elec­tron­ic struc­ture and reac­tiv­i­ty of 3d per­ovskite sur­face”, J. Chem. Phys. 137, 084703 (2012).
  2. James Lan­don, Ethan Deme­ter, Nilay İnoğlu, Chris Ketu­rakis, Israel E. Wachs, Rel­ja Vasić, Ana­toly I. Frenkel, John R. Kitchin, “Spec­tro­scop­ic char­ac­ter­i­za­tion of mixed Fe-Ni oxide elec­tro­cat­a­lysts for the oxy­gen evo­lu­tion reac­tion in alka­line elec­trolytes”, ACS Catal­y­sis, 2, 1793–1801 (2012).
  3. Sne­ha A. Akhade and John R. Kitchin*, Effects of strain, d-band fill­ing and oxi­da­tion state on the bulk elec­tron­ic struc­ture of cubic 3d per­ovskites, J. Chem. Phys. 135, 104702 (2011).
  4. N. Inoglu, and J.R. Kitchin, Iden­ti­fi­ca­tion of sul­fur tol­er­ant bimetal­lic sur­faces using DFT para­me­ter­ized mod­els and atom­istic ther­mo­dy­nam­ics, ACS Catal­y­sis, 1, 399–407 (2011).
  5. Isabela C. Man, Hai-Yan Su, Fed­eri­co Calle-Valle­jo, Heine A. Hansen, José I. Martínez, Nilay G. Inoglu, John Kitchin, Thomas F. Jaramil­lo, Jens K. Nørskov, Jan Ross­meisl, Uni­ver­sal­i­ty in Oxy­gen Evo­lu­tion Elec­tro-Catal­y­sis on Oxide Sur­faces, Chem­CatChem, 3, (2011).
  6. Spencer D. Miller, Nilay İnoğlu, and John R. Kitchin, Con­fig­u­ra­tional cor­re­la­tions in the cov­er­age depen­dent adsorp­tion ener­gies of oxy­gen atoms on late tran­si­tion met­al fcc (111) sur­faces, J. Chem­i­cal Physics, 134, 104709 (2011).
  7. R. Chao, J. R. Kitchin, K. Gerdes, E. M. Sabol­sky, and P. A. Sal­vador, Prepa­ra­tion of Meso­porous La0.8Sr0.2MnO3 Infil­trat­ed Coat­ings in Porous SOFC Cath­odes Using Evap­o­ra­tion-Induced Self-Assem­bly Meth­ods, ECS Trans­ac­tions, 35 (1) 2387–2399 (2011).
  8. W. Richard Ale­si Jr., McMa­han Gray, John R. Kitchin, CO2 Adsorp­tion on Sup­port­ed Mol­e­c­u­lar Ami­dine Sys­tems on Acti­vat­ed Car­bon, Chem­SusChem, 3(8), 948–956 (2010) Spe­cial issue on CO2 cap­ture and Seques­tra­tion.
  9. Nilay Inoglu, John R. Kitchin, Sim­ple mod­el explain­ing and pre­dict­ing cov­er­age-depen­dent atom­ic adsorp­tion ener­gies on tran­si­tion met­al sur­faces, Phys­i­cal Review B, 82, 045414 (2010).

Nature of Catalytic Active Surface Sites on Semiconductor Photocatalysts for Splitting of Water

Meeting Program — March 2013

 
Som­phonh Peter Phivi­lay
Operan­do Mol­e­c­u­lar Spec­troscopy & Catal­y­sis Lab­o­ra­to­ry
Depart­ment of Chem­i­cal Engi­neer­ing
Lehigh Uni­ver­si­ty
Beth­le­hem, PA 18015 USA
Stu­dent Speak­er

 
Abstract — One of society’s great chal­lenges for the 21st cen­tu­ry is the devel­op­ment of alter­na­tive ener­gy resources. Hydro­gen is con­sid­ered to be one of the poten­tial can­di­dates espe­cial­ly if it can be gen­er­at­ed from the pho­to­cat­alyt­ic con­ver­sion of cheap abun­dant H2O into clean non-car­bon H2 from solar ener­gy resources. Devel­op­ment of this clean, renew­able form of ener­gy will help to address our reliance on deplet­ed fos­sil fuel sup­plies and the envi­ron­men­tal prob­lems accom­pa­ny­ing its use.

Pho­to­cat­alyt­ic split­ting of waters pro­ceeds via gen­er­a­tion of excit­ed elec­trons and holes in the semi­con­duc­tor cat­a­lyst bulk lat­tice, the dif­fu­sion of the exci­tons through the semi­con­duc­tor lat­tice to the sur­face, and sur­face reac­tions of the exci­tons with water to split H2O to H2 and O2. The pho­to­catal­y­sis lit­er­a­ture, how­ev­er, has almost com­plete­ly neglect­ed the sur­face nature of pho­to­cat­a­lysts and focused on the semi­con­duc­tor cat­a­lyst bulk lat­tice that is only respon­si­ble for gen­er­a­tion of the excit­ed holes and elec­trons.

This pre­sen­ta­tion will exam­ine the anato­my of the sup­port­ed (Rh2-yCryO3)/(Ga1-xZnx)(N1-xOx) pho­to­cat­a­lysts that are able to split water with vis­i­ble light exci­ta­tion by deter­min­ing the nature of the bulk lat­tice (mm), sur­face region (~1–3 nm) and out­er­most sur­face lat­er (~0.3 nm) with unique cut­ting edge char­ac­ter­i­za­tion tech­niques.

Sulfur-Resistant Pd-Alloy Membranes for H2 Purification

Meeting Program — March 2013

 
James B. Miller
Depart­ment of Chem­i­cal Engi­neer­ing
Carnegie Mel­lon Uni­ver­si­ty

 
Abstract — Sep­a­ra­tion of hydro­gen from mixed gas streams is a key unit oper­a­tion in the gen­er­a­tion of car­bon-neu­tral fuels and elec­tric­i­ty from fos­sil- and bio-derived feed­stocks. Dense Pd mem­branes have received sig­nif­i­cant atten­tion for the sep­a­ra­tion appli­ca­tion in advanced gasi­fi­ca­tion process­es. Pd’s near-per­fect selec­tiv­i­ty reflects its unique inter­ac­tions with H2: mol­e­c­u­lar H2 dis­so­ci­ates on the cat­alyt­ic Pd sur­face to cre­ate H-atoms, which dis­solve into and dif­fuse through the Pd bulk, to even­tu­al­ly recom­bine on the down­stream side of the mem­brane. In prac­tice, Pd suf­fers from sev­er­al lim­i­ta­tions, includ­ing high cost, struc­tur­al insta­bil­i­ty, and deac­ti­va­tion by minor com­po­nents of the mixed gas, most notably H2S. Alloy­ing with minor com­po­nents, such as Cu, can be an effec­tive strat­e­gy for improv­ing mem­brane per­for­mance.

In col­lab­o­ra­tion with sci­en­tists at the Nation­al Ener­gy Tech­nol­o­gy Lab­o­ra­to­ry, we have com­bined mem­brane per­for­mance test­ing, com­pu­ta­tion­al mod­el­ing, and H2 dis­so­ci­a­tion activ­i­ty char­ac­ter­i­za­tion to pro­vide fun­da­men­tal under­stand­ing of the inter­ac­tions of H2 and H2S with Pd and PdCu alloys. We have shown that H2S influ­ences mem­brane per­for­mance by two dis­tinct mech­a­nisms: sur­face deac­ti­va­tion, which inhibits the dis­so­cia­tive adsorp­tion of H2, and reac­tion with the met­al to form a low-per­me­abil­i­ty sul­fide scale. The mech­a­nism that dom­i­nates depends on both alloy com­po­si­tion and oper­at­ing con­di­tions. Sig­nif­i­cant­ly, the sur­face of the sul­fide scale is itself active for H2 dis­so­ci­a­tion. Atom­istic mod­el­ing of the dis­so­ci­a­tion process pro­vides con­text for this obser­va­tion, show­ing that while the ener­getic bar­ri­er for H2 dis­so­ci­a­tion is high­er on Pd4S than on Pd, there exist reac­tion tra­jec­to­ries with rel­a­tive­ly low bar­ri­ers that can sus­tain the sep­a­ra­tion sequence at accept­able rates. Microkinec­tic analy­sis of H2-D2 exchange con­duct­ed over Pd and a series of PdCu alloys, both in the pres­ence and absence if H2S, con­firms this find­ing and pro­vides insight into the role of the Cu minor com­po­nent in impart­ing S-tol­er­ance to the alloy.

Final­ly, we have devel­oped a high through­put capa­bil­i­ty to explore alloy prop­er­ties over broad, con­tin­u­ous com­po­si­tion space, based on Com­po­si­tion Spread Alloy Film (CSAF) libraries of mod­el sep­a­ra­tion alloys. CSAFs are thin (~100 nm) films with com­po­si­tions that vary con­tin­u­ous­ly across the sur­face of a com­pact (~1cm2) sub­strate. Using a unique mul­ti­chan­nel microre­ac­tor for spa­tial­ly resolved mea­sure­ment of reac­tion kinet­ics across CSAF sur­faces, we have char­ac­ter­ized the kinet­ics of H2-D2 exchange across con­tin­u­ous Pd1-xCux and Pd1-x-yCuxAuy com­po­si­tion space.
 

James B. Miller

James B. Miller

Biog­ra­phy — Jim Miller is Asso­ciate Research Pro­fes­sor of Chem­i­cal Engi­neer­ing at Carnegie Mel­lon Uni­ver­si­ty, where he stud­ies advanced mate­ri­als for ener­gy-relat­ed appli­ca­tions in sep­a­ra­tions, catal­y­sis and chem­i­cal sens­ing. Jim earned BS, MS and PhD degrees at Carnegie Mel­lon and an MS at the Uni­ver­si­ty of Pitts­burgh. Before join­ing the fac­ul­ty in 2006, he worked in indus­try as a devel­op­er of cat­a­lysts, cat­alyt­ic process­es and chem­i­cal sen­sors for over 25 years. Jim is a two-time past pres­i­dent of the Pitts­burgh-Cleve­land Catal­y­sis Soci­ety; he recent­ly led the Society’s suc­cess­ful efforts to obtain tax exempt sta­tus in antic­i­pa­tion of NAM 2015. He is a win­ner of AIChE’s 2010 “Shin­ing Star” in recog­ni­tion of his vol­un­teer work in the Pitts­burgh Local Sec­tion.

Oxidative Dehydrogenation of Ethane to Ethylene

Meeting Program — February 2013

 
Anne M. Gaffney
AMG Catal­y­sis and Chem­istry Con­sult­ing, LLC
 
Abstract — This sem­i­nar will dis­cuss a new­ly patent­ed cat­alyt­ic process and cat­a­lyst for the selec­tive, oxida­tive dehy­dro­gena­tion (ODH) of ethane to eth­yl­ene. Recent advances in shale gas tech­nol­o­gy, espe­cial­ly as prac­ticed in the Unit­ed States, has sig­nif­i­cant­ly improved the eco­nom­ics around pro­duc­ing eth­yl­ene and has rev­o­lu­tion­ized man­u­fac­tur­ing approach­es to basic chem­i­cals, poly­mers and mate­ri­als. Ethane is sec­ond to methane as a major hydro­car­bon com­po­nent of shale gas, serv­ing as the pre­cur­sor to eth­yl­ene. Eth­yl­ene is used to pro­duce a wide vari­ety of con­sumer goods, includ­ing pack­ag­ing, build­ing & auto­mo­tive mate­ri­als, fibers, tires and bot­tles. In 2012, a num­ber of U.S. chem­i­cal com­pa­nies announced plans to invest in new plant capac­i­ty, expand exist­ing facil­i­ties, or re-open plants near shale gas sup­plies, pri­mar­i­ly based on the assump­tion that the U.S. is enter­ing a peri­od of sus­tained low nat­ur­al gas prices and grow­ing sup­ply.

This selec­tive ODH process pro­vides an alter­na­tive to eth­yl­ene pro­duc­tion via naph­tha or ethane crack­ing. In addi­tion to replac­ing these crack­ers and recy­cle crack­ers, the eth­yl­ene prod­uct efflu­ent from the ODH process may be used to feed eth­yl benzene/styrene monomer and eth­yl­ene oxide plants. The syn­the­sis, char­ac­ter­i­za­tion and cat­alyt­ic appli­ca­tions of the new, M1 struc­tured, mixed met­al oxide cat­a­lyst will be reviewed.
 

Anne M.  Gaffney

Anne M. Gaffney

Biog­ra­phy — Dr. Anne M. Gaffney joined INVISTA™ in 2011 as Direc­tor of R&D, Spe­cial­ty Mate­ri­als and is cur­rent­ly Pro­gram Leader for C11/C12™ R&D. She was pre­vi­ous­ly VP of Tech­nol­o­gy at Lum­mus Tech­nol­o­gy. Oth­er pri­or indus­tri­al roles include Senior Research Fel­low at Rohm and Haas, Senior Research Asso­ciate at DuPont and Man­ag­er of Catal­y­sis at ARCO Chem­i­cal Com­pa­ny. Anne is the inven­tor/­co-inven­tor of over 100 patents and author/­co-author of over 80 pub­li­ca­tions. She was select­ed as an ACS Fel­low in 2010 and holds sev­er­al oth­er awards, includ­ing the 2013 ACS award in Indus­tri­al Chem­istry and the 1999 Philadel­phia Catal­y­sis Club Award. Anne received her Ph.D. in Phys­i­cal Organ­ic Chem­istry from the Uni­ver­si­ty of Delaware and her B.A. in Chem­istry and Math­e­mat­ics from Mount Holyoke Col­lege. Anne’s endeav­ors and inter­ests include R&D Lead­er­ship, break -through tech­nolo­gies, het­ero­ge­neous catal­y­sis, selec­tive oxi­da­tion, cat­a­lyst syn­the­sis and char­ac­ter­i­za­tion. He is the recip­i­ent of the New York Catal­y­sis Soci­ety Excel­lence in Catal­y­sis Award, the North Amer­i­can Catal­y­sis Soci­ety Frank Cia­pet­ta Lec­ture­ship Award, the ACS Heroes in Chem­istry Award, and the Her­man Pines in Catal­y­sis.

Supported Metal Catalysts – Issues and Opportunities

Meeting Program — Janiary 2013

 
Stu­art Soled
Exxon­Mo­bil Research and Engi­neer­ing Co
Rt. 22 East
Annan­dale, NJ

 
Abstract — Sup­port­ed met­al oxides, met­als and sul­fides form a large frac­tion of indus­tri­al­ly impor­tant cat­a­lysts. Prepa­ra­tion of sup­port­ed cat­a­lysts can involve a rich chem­istry. We will detail dif­fer­ent prepa­ra­tion approach­es all aimed at con­trol­ling active site num­ber and site loca­tion. Issues involv­ing activ­i­ty, trans­port, and deac­ti­va­tion come into play. Site loca­tions are opti­mized on both mm and nm scale. Approach­es involv­ing elec­tro­sta­t­ic inter­ac­tions and sur­face com­plex for­ma­tion will be illus­trat­ed. We will describe approach­es to mak­ing sup­port­ed noble met­al cat­a­lysts on sil­i­ca as well as cat­a­lysts used in Fis­ch­er-Trop­sch chem­istry. The impor­tance of nanoscale homo­gene­ity on cat­a­lyst sta­bil­i­ty will be illus­trat­ed in sev­er­al exam­ples.
 
Biog­ra­phy — Stu­art Soled received his Ph.D in chem­istry from Brown Uni­ver­si­ty in 1973. He then did 4 year of post-doc­tor­al work in sol­id state chem­istry both at Brown Uni­ver­si­ty and in France, focus­ing on the syn­the­sis and char­ac­ter­i­za­tion of nov­el oxide and sul­fide mate­ri­als. He has been at Exxon’s Cor­po­rate Research Labs for more than 31 years. His research inter­ests lie in the syn­the­sis, char­ac­ter­i­za­tion and eval­u­a­tion of nov­el cat­alyt­ic mate­ri­als. He has worked exten­sive­ly on Fis­ch­er-Trop­sch chem­istry, sol­id acid and met­al catal­y­sis, and hydrotreat­ing. He is the coau­thor of more than 70 pub­li­ca­tions and over 100 U.S. patents. He worked on the team dis­cov­er­ing the Neb­u­la cat­a­lyst and has worked on a joint Exxon­Mo­bil-Albe­mar­le team to bring it to com­mer­cial real­i­ty. Neb­u­la has been pro­duc­ing low sul­fur diesel fuels in over 15 refin­ery units world­wide.

He is the recip­i­ent of the New York Catal­y­sis Soci­ety Excel­lence in Catal­y­sis Award, the North Amer­i­can Catal­y­sis Soci­ety Frank Cia­pet­ta Lec­ture­ship Award, the ACS Heroes in Chem­istry Award, and the Her­man Pines in Catal­y­sis.

A DFT study of the acid-catalyzed conversion of 2,5-dimethylfuran and ethylene to p-xylene

Meeting Program — November 2012

 
Nima Nikbin
Depart­ment of Chem­i­cal and Bio­mol­e­c­u­lar Engi­neer­ing
Uni­ver­si­ty of Delaware
Newark, DE
Stu­dent Pre­sen­ta­tion

 
Abstract — In this paper we present the detailed mech­a­nism for the con­ver­sion of DMF and eth­yl­ene to p-xylene. The mech­a­nism was cal­cu­lat­ed by gas-phase DFT (Den­si­ty-Func­tion­al The­o­ry) for the uncat­alyzed, the Brøn­st­ed acid-cat­alyzed and the Lewis acid-cat­alyzed reac­tion. The con­ver­sion con­sists of Diels-Alder cycload­di­tion and sub­se­quent dehy­dra­tion of the cycloadduct, an oxa-nor­bornene deriv­a­tive. Even though the DMF-eth­yl­ene cycload­di­tion is ther­mal­ly fea­si­ble, we find that Lewis acids can fur­ther low­er the acti­va­tion bar­ri­ers by decreas­ing the HOMO-LUMO gap of the addends. The cat­alyt­ic effect may be sig­nif­i­cant or neg­li­gi­ble depend­ing on whether the Diels-Alder reac­tion pro­ceeds in the nor­mal or the inverse elec­tron-demand direc­tion. We find that Brøn­st­ed acids are extreme­ly effec­tive at cat­alyz­ing the dehy­dra­tion of the oxa-nor­bornene deriv­a­tive, which, accord­ing to our cal­cu­la­tions, can­not pro­ceed uncat­alyzed. On the oth­er hand, we find that Brøn­st­ed acids do not cat­alyze the cycload­di­tion. Although strong Lewis acids like Li+ can cat­alyze the dehy­dra­tion, our cal­cu­la­tions indi­cate that rel­a­tive­ly ele­vat­ed tem­per­a­tures would be required as they are not as effec­tive as Brøn­st­ed acids. We argue that the spe­cif­ic syn­thet­ic route to p-xylene is kinet­i­cal­ly lim­it­ed by the Diels-Alder reac­tion when Brøn­st­ed acids are used and by the dehy­dra­tion when a Lewis acid is used, with the lat­ter being slow­er than the for­mer. Final­ly, we adduce exper­i­men­tal data that cor­rob­o­rate the the­o­ret­i­cal pre­dic­tions: we observe no activ­i­ty in the absence of a cat­a­lyst and a high­er turnover fre­quen­cy to p-xylene in the Brøn­st­ed acidic zeo­lite HY than in the Lewis acidic zeo­lite NaY.