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Volumn 5, Issue 6, 2015, Pages 3342-3353

Unintuitive inverse dependence of the apparent turnover frequency on precatalyst concentration: A quantitative explanation in the case of ziegler-type nanoparticle catalysts made from [(1,5-COD)Ir(μ-O2C8H15)]2 and AlEt3

Author keywords

hydrogenation catalysis; inverse dependence of turnover frequency on catalyst concentration; kinetics and mechanism; turnover frequency; Ziegler type nanoclusters

Indexed keywords

ALUMINUM COMPOUNDS; DIMERS; DISSOCIATION; HYDROGENATION; KINETICS; NANOCLUSTERS; NANOPARTICLES; OLEFINS;

EID: 84930633355     PISSN: None     EISSN: 21555435     Source Type: Journal    
DOI: 10.1021/acscatal.5b00347     Document Type: Article
Times cited : (28)

References (53)
  • 8
    • 84855930381 scopus 로고    scopus 로고
    • Crabtree, R. H. Chem. Rev. 2012, 112, 1536-1554 10.1021/cr2002905
    • (2012) Chem. Rev. , vol.112 , pp. 1536-1554
    • Crabtree, R.H.1
  • 13
    • 84930652880 scopus 로고    scopus 로고
    • 3 has been shown to be.(10b).
    • 3 has been shown to be.(10b).
  • 16
    • 84930662297 scopus 로고    scopus 로고
    • As noted by Bartholomew(12a) (see also Boudart's original work(39)), "The turnover frequency (TOF) is a specific reaction rate based on the number of active sites." The authors further specify that the "specific reaction rate" = 1/(vQ) × d[ n ]/d t where v is the stoichiometric coefficient in the reaction; n is the number of moles of the species; t is time; and Q is the volume, weight, or surface area of the catalyst. Units are molecules/site-second or 1/s.
    • As noted by Bartholomew(12a) (see also Boudart's original work(39)), "The turnover frequency (TOF) is a specific reaction rate based on the number of active sites." The authors further specify that the "specific reaction rate" = 1/(vQ) × d[ n ]/d t where v is the stoichiometric coefficient in the reaction; n is the number of moles of the species; t is time; and Q is the volume, weight, or surface area of the catalyst. Units are molecules/site-second or 1/s.
  • 29
    • 84930667829 scopus 로고    scopus 로고
    • When the Finke-Watzky (F-W) two step (A → B, A + B → 2B) slow, continuous nucleation and autocatalytic surface-growth mechanism of nanoparticle formation(23) is followed, then a size vs time relationship can be derived for transition metal nanoparticles, as done in the above cited publication.(24) However, lower concentrations often yield fewer nuclei, and that tends to make larger, not smaller, particles.
    • When the Finke-Watzky (F-W) two step (A → B, A + B → 2B) slow, continuous nucleation and autocatalytic surface-growth mechanism of nanoparticle formation(23) is followed, then a size vs time relationship can be derived for transition metal nanoparticles, as done in the above cited publication.(24) However, lower concentrations often yield fewer nuclei, and that tends to make larger, not smaller, particles.
  • 30
    • 84930645833 scopus 로고    scopus 로고
    • n nanocluster hydrogenation catalysts, the larger particles typically being more active.(25b, 25c)
    • n nanocluster hydrogenation catalysts, the larger particles typically being more active.(25b, 25c)
  • 34
    • 1942467986 scopus 로고    scopus 로고
    • For a lead reference, see the following and references therein
    • For a lead reference, see the following and references therein: Doll, K. M.; Finke, R. G. Inorg. Chem. 2004, 43, 2611-2623 10.1021/ic030141c
    • (2004) Inorg. Chem. , vol.43 , pp. 2611-2623
    • Doll, K.M.1    Finke, R.G.2
  • 35
    • 84930647432 scopus 로고
    • See also the discussion of trace impurities, as well as the other valuable hints for performing kinetic studies, in; Bernasconi, Wiley: New York, Vol.
    • See also the discussion of trace impurities, as well as the other valuable hints for performing kinetic studies, in Investigations of Rates and Mechanisms of Reactions; Bernasconi, Ed.; Wiley: New York, 1986; Vol. VI, p 238.
    • (1986) Investigations of Rates and Mechanisms of Reactions , vol.6 , pp. 238
  • 39
    • 84930647346 scopus 로고    scopus 로고
    • The DFT calculations performed by Pawluk et. al(32a) on naked, unligated Ir particles are also consistent with the constant particle sizes observed. Specifically, Pawluk and co-workers find that (naked; unligated) Ir particles prefer a simple cubic structure until a 48 atom particle (5.91 eV per Ir atom binding energy) is reached, at which point the transition to face-centered cubic occurs. This 48 atom (about 1.1 nm diameter) limit restricts coalescence of at least naked, smaller nanoparticles because energetically unfavorable surface rearrangements would be required, again with the caveat here that these calculations refer strictly to only naked, unligated Ir nanoparticles.
    • The DFT calculations performed by Pawluk et. al(32a) on naked, unligated Ir particles are also consistent with the constant particle sizes observed. Specifically, Pawluk and co-workers find that (naked; unligated) Ir particles prefer a simple cubic structure until a 48 atom particle (5.91 eV per Ir atom binding energy) is reached, at which point the transition to face-centered cubic occurs. This 48 atom (about 1.1 nm diameter) limit restricts coalescence of at least naked, smaller nanoparticles because energetically unfavorable surface rearrangements would be required, again with the caveat here that these calculations refer strictly to only naked, unligated Ir nanoparticles.
  • 42
    • 84930655818 scopus 로고    scopus 로고
    • x equilibrium as a function of the specific L, bidendate L-L, and temperature. ". This statement is still true in.
    • x equilibrium as a function of the specific L, bidendate L-L, and temperature... ". This statement is still true in 2015.
    • (2015)
  • 43
    • 85073174281 scopus 로고    scopus 로고
    • app values -makes sense only when the rate law for each system being compared is known.
    • app values makes sense only when the rate law for each system being compared is known.
    • Kozuch1
  • 45
    • 84874584250 scopus 로고    scopus 로고
    • Lente, G. ACS Catal. 2013, 3, 381-382 10.1021/cs300846b
    • (2013) ACS Catal. , vol.3 , pp. 381-382
    • Lente, G.1
  • 46
    • 0000074194 scopus 로고
    • For a classic contribution on the definition and proper use of TOF in catalysis, see
    • For a classic contribution on the definition and proper use of TOF in catalysis, see: Boudart, M. Chem. Rev. 1995, 95, 661-666 10.1021/cr00035a009
    • (1995) Chem. Rev. , vol.95 , pp. 661-666
    • Boudart, M.1
  • 51
    • 84930640702 scopus 로고    scopus 로고
    • See also the concept of a "Hydrogen Reservoir", as discussed in the two Ph.D. theses listed as references 8 and 9 in this 1994 paper.(43)
    • See also the concept of a "Hydrogen Reservoir", as discussed in the two Ph.D. theses listed as references 8 and 9 in this 1994 paper.(43)


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