Experimental and DFT Studies of Initiation Processes for Butane Isomerization over Sulfated-Zirconia Catalysts

Hong, Zhe; Fogash, K.B.; Watwe, Ramchandra M.; Kim, B.; Masqueda-Jiménez, B.I.; Natal-Santiago, M.A.; Hill, Josephine M.; Dumesic, James A.

doi:10.1006/jcat.1998.2163

Cited by 50 publications

(33 citation statements)

References 63 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…There are several potential reasons for this behavior, (i) assuming only a monomolecular mechanism, the actual turnover rate per site is higher, (ii) a higher site density favors the bimolecular mechanism with its lower activation energy [40] over the monomolecular mechanism, or (iii) there is another route to "active sites" (carbenium ions) without the formation of water, e.g. via protonation and cleavage of H 2 , which, however, has only been demonstrated for unpromoted sulfated zirconia [41].…”

Section: Catalyst Start-up and Performancementioning

confidence: 99%

In situ spectroscopic investigation of activation, start-up and deactivation of promoted sulfated zirconia catalysts

et al. 2006

View full text Add to dashboard Cite

Sulfated zirconia (SZ), unpromoted and promoted with 0.5-2.0 wt% Mn or Fe, was investigated by in situ IR and UV-vis spectroscopy during activation at 723-773 K and interaction with n-butane at 298-323 K. During start-up of the catalysts, the isomerization rate increases with the amount of water that is being formed, consistent with an activation of n-butane via oxidative dehydrogenation. Sulfate is the most likely oxidizing agent because activity is also observed for unpromoted SZ and without reduction of Mn. Isomerized species were also found on the surface of Fepromoted SZ after exposure to n-butane without water formation indicating other yet unknown initiation pathways. During isomerization, Lewis acid sites on Fe-promoted SZ are blocked by water; the valence of Mn decreases only if the catalyst was previously activated in O 2 . Stable species absorbing at 2820-2840 cm -1 detected on the surface of SZ and Fe-promoted SZ after contact with n-butane at 298 K are tentatively ascribed to alkoxides, which may be side-products or intermediates. These species differ slightly for the two catalysts, reflecting the different structural and electronic properties of the materials.

show abstract

Section: Catalyst Start-up and Performancementioning

confidence: 99%

In situ spectroscopic investigation of activation, start-up and deactivation of promoted sulfated zirconia catalysts

et al. 2006

View full text Add to dashboard Cite

show abstract

“…Nonetheless, contradiction on which is the adequate mechanism appears since the catalyst was formulated [3,7]. In recent studies on the isomerization mechanism [24][25][26]29,30], the authors indicated that, in the presence of hydrogen in the feed, the rate of butane isomerization decreases and the reaction pathway is apparently monomolecular. At high hydrogen pressure the reaction mechanism shifts towards a bimolecular pathway and hydrogenolysis.…”

Section: Discussionmentioning

confidence: 96%

“…At high hydrogen pressure the reaction mechanism shifts towards a bimolecular pathway and hydrogenolysis. Apparently, other promotional effect of platinum is the olefin formation, as the in-situ reactive intermediate of the surface chain isomerization reaction, leading the reaction by a bimolecular pathway [30]. Moreover, platinum promotes the olefin formation leading the reaction by a bimolecular pathway.…”

Section: Discussionmentioning

confidence: 98%

Effect of Pt Incorporation into Ni/ZrO2–SO4=/Al2O3 Catalyst for n-Butane Isomerization

et al. 2006

View full text Add to dashboard Cite

Three Ni/ZrO 2 -SO 4 = /Al 2 O 3 catalysts with different concentrations of platinum (0.2, 0.3 and 0.4 wt%) were prepare and tested for n-butane isomerization reaction at 338 K, in absence and in presence of hydrogen. The results shown that, at low temperature, platinum contributes to the olefin or butyl ion formation and the reaction follows a bimolecular pathway. However, when the reaction occurs in the presence of hydrogen, the formation of butyl ions is inhibited. The main feature of platinum addition is the stabilization of the catalytic activity, which is indicated by the slow deactivation constants compared to that of the unpromoted catalyst.KEY WORDS: n-butane isomerization; Pt catalyst; Ni/ZrO 2 -SO 4 = /Al 2 O 3 catalyst.

show abstract

“…Butane isomerization over WZ can be viewed as a surface chain reaction comprising initiation, propagation, and termination steps [25]. In this paper, we are interested in the initiation process, which may be promoted by metals.…”

Section: Possible Reaction Pathways and Effect Of Promoters In N-butamentioning

confidence: 99%

Platinum- and iron-doubly promoted tungstated zirconia catalyst for n-butane isomerization reaction

Wong

Cheng

et al. 2005

Applied Catalysis A: General

View full text Add to dashboard Cite

Experimental and DFT Studies of Initiation Processes for Butane Isomerization over Sulfated-Zirconia Catalysts

Cited by 50 publications

References 63 publications

In situ spectroscopic investigation of activation, start-up and deactivation of promoted sulfated zirconia catalysts

In situ spectroscopic investigation of activation, start-up and deactivation of promoted sulfated zirconia catalysts

Effect of Pt Incorporation into Ni/ZrO2–SO4=/Al2O3 Catalyst for n-Butane Isomerization

Platinum- and iron-doubly promoted tungstated zirconia catalyst for n-butane isomerization reaction

Contact Info

Product

Resources

About