The structure sensitivity of n-heptane dehydrocyclization and hydrogenolysis catalyzed by platinum single crystals at atmospheric pressure

Gillespie, Walter D.; Herz, Richard K.; Petersen, Eugene E.; Somorjai, Gábor A.

doi:10.1016/0021-9517(81)90324-9

Cited by 62 publications

(15 citation statements)

References 6 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…On the other hand, the variety of the available ultrahigh vacuum (UHV) techniques, capable of studying mechanisms and intermediates of different reactions, often require single crystal surfaces as model catalysts. Platinum in the form of a single crystal has been extensively studied as a catalyst for the dehydrocyclization reaction. − Although these preliminary studies provided some insight into reactivity of platinum toward the C−C and C−H bond activation, results related to the aromatization reaction were complicated due to existence of other competing reactions (isomerization, hydrogenolysis, etc.) on a platinum surface.…”

Section: Introductionmentioning

confidence: 99%

Mechanism of Dehydrocyclization of 1-Hexene to Benzene on Cu₃Pt(111): Identification of 1,3,5-Hexatriene as Reaction Intermediate

et al. 1998

View full text Add to dashboard Cite

We report here ultrahigh vacuum studies of the dehydrocyclization reaction of submonolayer coverages of 1-hexene to benzene on a Cu3Pt(111) single crystal surface, using reflection-absorption infrared spectroscopy (RAIRS), near edge X-ray absorption fine structure (NEXAFS) studies, and temperatureprogrammed reaction/desorption (TPR/D) spectrometry. As discussed in a previous TPR/D paper, at surface coverages up to 13% of monolayer saturation, 1-hexene forms benzene on a Cu3Pt(111) surface. Selectivity to benzene formation is 70 ( 10%, with the remaining 30 ( 10% of the adsorbed 1-hexene dehydrogenating irreversibly to surface carbon and H2. For higher coverages, molecular desorption commences. Spectroscopic identification of the intermediates of the reaction of 1-hexene and other model compounds, such as a 1,3,5-hexatriene, with a Cu3Pt(111) surface suggests that 1-hexene and 1,3,5-hexatriene have a common intermediate, and this intermediate has been identified as a rehybridized hexatriene species. Other model compounds, such as trans-3-hexene, have also been used to provide further understanding of the mechanism of the aromatization reaction.

show abstract

Section: Introductionmentioning

confidence: 99%

Mechanism of Dehydrocyclization of 1-Hexene to Benzene on Cu₃Pt(111): Identification of 1,3,5-Hexatriene as Reaction Intermediate

et al. 1998

View full text Add to dashboard Cite

show abstract

“…The interest was based on the unusual reactivity of this noble metal toward reactions with hydrocarbons and their fragments. Pure platinum proved to be a poor catalyst for aromatization reactions if the cyclization was one of the steps of this process, because of complications related to isomerization and hydrogenolysis − competing with dehydrocyclization reaction. However, when aromatization was achieved by dehydrogenation of C 6 cyclic hydrocarbons, platinum showed excellent activity in this reaction. − The only complication to this reaction was the complete decomposition pathway leaving carbonaceous deposits on platinum surfaces even after benzene was formed.…”

Section: Introductionmentioning

confidence: 99%

Mechanism of Dehydrocyclization of 1-Hexene to Benzene on Cu₃Pt(111)

Teplyakov

Bent

1997

J. Phys. Chem. B

View full text Add to dashboard Cite

Even though dehydrocyclization is widely practiced in heterogeneous catalysis for the conversion of straight chain hydrocarbons into aromatic compounds, knowledge of the mechanism of this process remains limited, largely because it has not previously been possible to carry out the reaction under conditions amenable to detailed mechanistic studies. We report here ultrahigh vacuum studies of the dehydrocyclization of submonolayer coverages of 1-hexene to benzene on a Cu3Pt(111) single-crystal surface. On the basis of temperature-programmed reaction/desorption (TPR/D) studies of dehydrocyclization of 1-hexene as compared to the reactions of cyclohexene, 1,3-cyclohexadiene, 1,4-cyclohexadiene, benzene, 1,3-hexadiene, and 1,3,5-hexatriene with a Cu3Pt(111) surface, it is found that a rate-determining step in the overall reaction is cyclization. The obtained results show that at low coverages of mono- and bi-unsaturated cyclic compounds, benzene is the only gas-phase hydrocarbon product of reaction of these compounds with a Cu3Pt(111) surface, while after a certain threshold in coverage, molecular desorption of these compounds commences. The temperature of benzene evolution for all the cyclic compounds studied is between 200 and 300 K, whereas for linear chain hydrocarbons this temperature is ∼400 K. TPR/D studies of product hydrogen evolution show that all cyclic compounds evolve hydrogen upon reaction with the surface at the temperatures close to that of hydrogen recombination−desorption reaction, 220−290 K. On the other hand, 1-hexene evolves hydrogen upon reaction with this surface at two different temperatures: ∼270 and ∼405 K. Combining these results with the studies of hydrogen evolution from 1,3,5-hexatriene, which occurs at 400 K, we suggest that cyclization is a rate-determining step and that mono- and bi-unsaturated C6 cyclic compounds are not the reaction intermediates for the dehydrocyclization of 1-hexene to benzene.

show abstract

“…[11] The only experimental study on kink defects as active sites to date is a non-local study on the reactions of nheptane catalyzed by platinum single-crystal surfaces. [30] Two kinds of kink sites, which we name I and II, may exist at a step edge, in analogy to different enantiomers of chiral objects (Figure 3 these experiments are of type kink I (around 95 %), while only about 5 % are of kink II type, which we attribute to a slight misorientation of the surface during sample cutting, and therefore our analysis focuses on type I kink sites. At room temperature we expect kinks on the Au(10,7,7) surface to be mobile along the step edge, in analogy to vicinal Cu(111) surfaces.…”

mentioning

confidence: 99%

Polymerization on Stepped Surfaces: Alignment of Polymers and Identification of Catalytic Sites

et al. 2012

View full text Add to dashboard Cite

Kinky catalysis: Surface defects, such as step edges and kinks, are thought to be the ‘active sites’ that induce site‐specific chemical reactions on catalytic materials. The catalytic dissociation of a bromine atom from an organic molecule is shown to occur at kink sites on the stepped Au(10,7,7) surface (see scheme; Br=red). The anisotropic surface also facilitates the production of highly aligned polymers, formed by on‐surface covalent coupling of monomer units.

show abstract

The structure sensitivity of n-heptane dehydrocyclization and hydrogenolysis catalyzed by platinum single crystals at atmospheric pressure

Cited by 62 publications

References 6 publications

Mechanism of Dehydrocyclization of 1-Hexene to Benzene on Cu₃Pt(111): Identification of 1,3,5-Hexatriene as Reaction Intermediate

Mechanism of Dehydrocyclization of 1-Hexene to Benzene on Cu₃Pt(111): Identification of 1,3,5-Hexatriene as Reaction Intermediate

Mechanism of Dehydrocyclization of 1-Hexene to Benzene on Cu₃Pt(111)

Polymerization on Stepped Surfaces: Alignment of Polymers and Identification of Catalytic Sites

Contact Info

Product

Resources

About

The structure sensitivity of n-heptane dehydrocyclization and hydrogenolysis catalyzed by platinum single crystals at atmospheric pressure

Cited by 62 publications

References 6 publications

Mechanism of Dehydrocyclization of 1-Hexene to Benzene on Cu3Pt(111): Identification of 1,3,5-Hexatriene as Reaction Intermediate

Mechanism of Dehydrocyclization of 1-Hexene to Benzene on Cu3Pt(111): Identification of 1,3,5-Hexatriene as Reaction Intermediate

Mechanism of Dehydrocyclization of 1-Hexene to Benzene on Cu3Pt(111)

Polymerization on Stepped Surfaces: Alignment of Polymers and Identification of Catalytic Sites

Contact Info

Product

Resources

About

Mechanism of Dehydrocyclization of 1-Hexene to Benzene on Cu₃Pt(111): Identification of 1,3,5-Hexatriene as Reaction Intermediate

Mechanism of Dehydrocyclization of 1-Hexene to Benzene on Cu₃Pt(111): Identification of 1,3,5-Hexatriene as Reaction Intermediate

Mechanism of Dehydrocyclization of 1-Hexene to Benzene on Cu₃Pt(111)