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Impact of Co‐Components on the State of Pd and the Performance of Supported Pd/TiO 2 Catalysts in the Gas‐Phase Acetoxylation of Toluene
Author(s) -
Gatla Suresh,
Madaan Neetika,
Radnik Jörg,
Kalevaru Venkata Narayana,
Lücke Bernhard,
Martin Andreas,
Bentrup Ursula,
Brückner Angelika
Publication year - 2011
Publication title -
chemcatchem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.497
H-Index - 106
eISSN - 1867-3899
pISSN - 1867-3880
DOI - 10.1002/cctc.201100225
Subject(s) - catalysis , toluene , metal , transition metal , palladium , chemistry , carbon fibers , phase (matter) , carbon monoxide , inorganic chemistry , materials science , nuclear chemistry , organic chemistry , composite number , composite material
The effect of the co‐components Mn, Co, Au, and Sb with a wide range of standard reduction potentials (Mn 2+ /Mn: E °=−1.18 V; Co 2+ /Co: E °=−0.28 V; Sb 3+ /Sb: E °=+0.2 V; Au 3+ /Au: E °=+1.52 V) on the catalytic performance of 10 wt % Pd, 8 wt % M/TiO 2 (M=Mn, Co, Sb, Au) catalysts in the gas‐phase acetoxylation of toluene to benzyl acetate has been studied. Co‐components with low E ° are more active, but less selective than those with high E °. Co‐components with low E ° (Mn, Co) stabilize Pd in its oxidized form, whereas those with high E ° (Sb, Au) support the formation of metallic Pd. Sb and Au are incorporated into the Pd lattice, whereas Mn and Co are enriched at the surface during time on stream. Carbon is deposited on all catalysts during the reaction. However, for Mn‐ and Co‐containing catalysts, carbon is incorporated into the metal particles, whereas it is deposited on top of Pd particles modified with Sb and Au, which leads to faster deactivation.