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  • In Situ DDR-UV-Vis and Raman spectroscopic study of titania promoting effect on silica supported tungsten catalysts for enhanced propylene metathesis

This content will become publicly available on March 1, 2026

Title: In Situ DDR-UV-Vis and Raman spectroscopic study of titania promoting effect on silica supported tungsten catalysts for enhanced propylene metathesis
Tungsten based catalysts supported on silica (zWOX/SiO2) and silica promoted by titania (zWOX/yTiOX/SiO2) were studied for their catalytic activity towards propylene metathesis. The catalysts were prepared by a simple incipient wetness impregnation method using a large pore SiO2 of intermediate surface area (∼50 m2/g). Catalytic activity studies carried out in a fixed-bed reactor (723 K, 101 kPa propylene) indicated that propylene conversion increased with increasing W loading in zWOx/SiO2 catalysts (z = 0.5−6 W/nm2). It was shown that the catalytic activity of a poorly WOX dispersed 6WOX/SiO2 catalyst could be enhanced and maximized by an optimum titania promotion of 2 wt% TiO2 (∼3 Ti/nm2). In situ differential diffuse reflectance (DDR) UV-Vis spectroscopy at reaction conditions showed that TiOX domain size increased with increases in titania loading from isolated TiOX to TiOX clusters to TiO2 nanocrystals. The UV-Vis results also evidenced the existence of highly dispersed isolated WOX species, WOX clusters, and WO3 nanoparticles in the 6WOX/yTiOX/SiO2 (y = 0.5−6 wt% TiO2 or ∼0.7–9 Ti/nm2) catalysts. In situ DDR-UV-Vis, Raman, and mass spectrometry during propylene metathesis, and catalyst oxidation and reduction revealed the reasons for an optimum amount of titania promoter in 6WOX/2TiOX/SiO2. They were the result of a balanced interplay between two factors: (1) enhanced WOx species dispersion due to the presence of a trimeric TiOX cluster and (2) absence of catalyst deactivation (present at high TiO2 loadings) due to the trimeric TiOX cluster poor reactivity towards coke formation.  more » « less
Award ID(s):
1847655
PAR ID:
10650418
Author(s) / Creator(s):
; ; ; ;
Publisher / Repository:
Elsevier
Date Published:
Journal Name:
Catalysis Today
Volume:
447
Issue:
C
ISSN:
0920-5861
Page Range / eLocation ID:
115138
Subject(s) / Keyword(s):
Tungsten oxide Titania promoter Olefin metathesis In situ Raman spectroscopy In situ UV-Visible spectroscopy Differential diffuse reflectance In situ band gap energy
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
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