The Enhancing Effect of Brønsted Acidity of Supported MoOx Species on their Activity and Selectivity in Ethylene/trans‐2‐Butene Metathesis. Issue 6 (8th April 2014)

• Record Type: Journal Article
• Authors: Hahn, Tobias; Bentrup, Ursula; Armbrüster, Marc; Kondratenko, Evgenii V.; Linke, David
• Is Part Of: ChemCatChem. Volume 6:Issue 6(2014:Jun.)
• Page Start: 1664
• Page End: 1672
• Publication Date: 2014-04-08
• Subjects: Catalysis -- Periodicals; 541.39505
• DOI: 10.1002/cctc.201400040
• Languages: English
• ISSNs: 1867-3880

Abstract

<abstract abstract-type="main" xml:lang="en"> <title>Abstract</title> <p>Supported catalysts with a nominal Mo surface density of 0.15 and 1.5 Mo atoms nm⁻² were synthesized by impregnation of alumina, silica, and alumina–silica supports with silica content between 1 and 70 wt %. They were tested for their activity and selectivity in the metathesis of ethylene and <italic>trans</italic>‐2‐butene to propene between 343 and 603 K at 125 kPa. The catalysts were characterized by UV/Vis, Raman, and IR spectroscopy, XRD and H₂ temperature‐programmed reduction for elucidating the distribution, degree of polymerization, reducibility, and acidity of MoO_{<italic>x</italic>} species. We established that Brønsted acidity of highly dispersed tetrahedral and polymerized octahedral MoO_{<italic>x</italic>} species is required to ensure high metathesis activity. The acidic character of these species is influenced by their structure and support. Tetrahedral MoO_{<italic>x</italic>} species with Brønsted acidic character are only formed on supports possessing such acidity, whereas Brønsted acidic octahedral MoO_{<italic>x</italic>} is also created on supports without such acidic sites.</p> </abstract>