Sulfided Pt Catalysts: Monitoring surface chemical state and catalytic properties in n-hexane reactions

Research output: Contribution to journalArticle

14 Citations (Scopus)

Abstract

The amount and valence state of sulfur in sulfided Pt catalysts was monitored, together with parallel studies of the catalytic properties of these catalysts in order to clarify the catalytic effect of S in different chemical states on reactions of low-temperature n-hexane reforming. Pt black and 6% Pt/SiO2 (EUROPT-1) were sulfided by H2/H2S. X-ray photoelectron spectroscopy (XPS) detected both sulfate and sulfide. The chemical state of Pt corresponded to metallic Pt with low amounts of S containing surface adlayer and/or PtS present. This could be observed with Pt black and also with EUROPT. With S present, both catalysts lost ca 95% of their activity in n-hexane transformation at 603 K, n-hexenes being the predominant products. Prolonged runs with n-hexane as well as regenerations using O2 and H2 removed most sulfidic S from Pt black and about half of the original activity came back. Isomers and methylcyclopentane were produced in this state with high selectivities. Some reactivation of EUROPT (where no sulfate could be detected) occurred within one single run. A uniform scheme is proposed to describe the effects of sulfate and sulfide. Accordingly, sulfate acts as a structural modifier occupying a fraction of the active surface. Sulfide in small amounts, in turn, has a bonding modifier effect and poisons selectively benzene and fragmentation, enhancing (within the reduced activity) the selectivity of C5-cyclization and, possibly, also that of isomerization.

Original languageEnglish
Pages (from-to)245-251
Number of pages7
JournalJournal of Catalysis
Volume175
Issue number2
Publication statusPublished - 1998

Fingerprint

Hexane
Sulfates
sulfates
Sulfides
sulfides
catalysts
Catalysts
Monitoring
selectivity
poisons
hexenes
Poisons
Cyclization
Reforming reactions
Isomerization
Benzene
regeneration
Sulfur
Isomers
isomerization

ASJC Scopus subject areas

  • Catalysis
  • Process Chemistry and Technology

Cite this

Sulfided Pt Catalysts : Monitoring surface chemical state and catalytic properties in n-hexane reactions. / Paál, Zoltán; Muhler, Martin; Matusek, Károly.

In: Journal of Catalysis, Vol. 175, No. 2, 1998, p. 245-251.

Research output: Contribution to journalArticle

@article{0379960079be4308a9e75e29f4e0cf50,
title = "Sulfided Pt Catalysts: Monitoring surface chemical state and catalytic properties in n-hexane reactions",
abstract = "The amount and valence state of sulfur in sulfided Pt catalysts was monitored, together with parallel studies of the catalytic properties of these catalysts in order to clarify the catalytic effect of S in different chemical states on reactions of low-temperature n-hexane reforming. Pt black and 6{\%} Pt/SiO2 (EUROPT-1) were sulfided by H2/H2S. X-ray photoelectron spectroscopy (XPS) detected both sulfate and sulfide. The chemical state of Pt corresponded to metallic Pt with low amounts of S containing surface adlayer and/or PtS present. This could be observed with Pt black and also with EUROPT. With S present, both catalysts lost ca 95{\%} of their activity in n-hexane transformation at 603 K, n-hexenes being the predominant products. Prolonged runs with n-hexane as well as regenerations using O2 and H2 removed most sulfidic S from Pt black and about half of the original activity came back. Isomers and methylcyclopentane were produced in this state with high selectivities. Some reactivation of EUROPT (where no sulfate could be detected) occurred within one single run. A uniform scheme is proposed to describe the effects of sulfate and sulfide. Accordingly, sulfate acts as a structural modifier occupying a fraction of the active surface. Sulfide in small amounts, in turn, has a bonding modifier effect and poisons selectively benzene and fragmentation, enhancing (within the reduced activity) the selectivity of C5-cyclization and, possibly, also that of isomerization.",
author = "Zolt{\'a}n Pa{\'a}l and Martin Muhler and K{\'a}roly Matusek",
year = "1998",
language = "English",
volume = "175",
pages = "245--251",
journal = "Journal of Catalysis",
issn = "0021-9517",
publisher = "Academic Press Inc.",
number = "2",

}

TY - JOUR

T1 - Sulfided Pt Catalysts

T2 - Monitoring surface chemical state and catalytic properties in n-hexane reactions

AU - Paál, Zoltán

AU - Muhler, Martin

AU - Matusek, Károly

PY - 1998

Y1 - 1998

N2 - The amount and valence state of sulfur in sulfided Pt catalysts was monitored, together with parallel studies of the catalytic properties of these catalysts in order to clarify the catalytic effect of S in different chemical states on reactions of low-temperature n-hexane reforming. Pt black and 6% Pt/SiO2 (EUROPT-1) were sulfided by H2/H2S. X-ray photoelectron spectroscopy (XPS) detected both sulfate and sulfide. The chemical state of Pt corresponded to metallic Pt with low amounts of S containing surface adlayer and/or PtS present. This could be observed with Pt black and also with EUROPT. With S present, both catalysts lost ca 95% of their activity in n-hexane transformation at 603 K, n-hexenes being the predominant products. Prolonged runs with n-hexane as well as regenerations using O2 and H2 removed most sulfidic S from Pt black and about half of the original activity came back. Isomers and methylcyclopentane were produced in this state with high selectivities. Some reactivation of EUROPT (where no sulfate could be detected) occurred within one single run. A uniform scheme is proposed to describe the effects of sulfate and sulfide. Accordingly, sulfate acts as a structural modifier occupying a fraction of the active surface. Sulfide in small amounts, in turn, has a bonding modifier effect and poisons selectively benzene and fragmentation, enhancing (within the reduced activity) the selectivity of C5-cyclization and, possibly, also that of isomerization.

AB - The amount and valence state of sulfur in sulfided Pt catalysts was monitored, together with parallel studies of the catalytic properties of these catalysts in order to clarify the catalytic effect of S in different chemical states on reactions of low-temperature n-hexane reforming. Pt black and 6% Pt/SiO2 (EUROPT-1) were sulfided by H2/H2S. X-ray photoelectron spectroscopy (XPS) detected both sulfate and sulfide. The chemical state of Pt corresponded to metallic Pt with low amounts of S containing surface adlayer and/or PtS present. This could be observed with Pt black and also with EUROPT. With S present, both catalysts lost ca 95% of their activity in n-hexane transformation at 603 K, n-hexenes being the predominant products. Prolonged runs with n-hexane as well as regenerations using O2 and H2 removed most sulfidic S from Pt black and about half of the original activity came back. Isomers and methylcyclopentane were produced in this state with high selectivities. Some reactivation of EUROPT (where no sulfate could be detected) occurred within one single run. A uniform scheme is proposed to describe the effects of sulfate and sulfide. Accordingly, sulfate acts as a structural modifier occupying a fraction of the active surface. Sulfide in small amounts, in turn, has a bonding modifier effect and poisons selectively benzene and fragmentation, enhancing (within the reduced activity) the selectivity of C5-cyclization and, possibly, also that of isomerization.

UR - http://www.scopus.com/inward/record.url?scp=0011764386&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0011764386&partnerID=8YFLogxK

M3 - Article

AN - SCOPUS:0011764386

VL - 175

SP - 245

EP - 251

JO - Journal of Catalysis

JF - Journal of Catalysis

SN - 0021-9517

IS - 2

ER -