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Preparation of Ti/SiO2 catalysts by chemical vapor deposition method for olefin epoxidation with cumene hydroperoxide

Paper ID Volume ID Publish Year Pages File Format Full-Text
43953 45997 2006 7 PDF Available
Title
Preparation of Ti/SiO2 catalysts by chemical vapor deposition method for olefin epoxidation with cumene hydroperoxide
Abstract

Ti/SiO2 epoxidation catalysts with titanium concentration ≤1.12 μmol/m2 were prepared by chemical deposition of TiCl4 vapor on silica gel at 900 °C for 0.5–3 h. A zero-order rate law was able to satisfactorily describe the deposition process in the range of Ti ≤1 μmol/m2. The CVD-prepared Ti/SiO2 catalysts were used to catalyze the epoxidation of propylene and 1-octene to the corresponding epoxides (propylene oxide and 1,2-epoxyoctane) with cumene hydroperoxide (CHP) and tert-butyl hydroperoxide (TBHP) as the oxidants. The epoxide selectivity increased rapidly with Ti concentration. For the catalyst containing the maximum Ti concentration, the epoxide selectivities were insensitive to the oxidant type, and had 97% 1,2-epoxyoctane yield and 93% propylene oxide yield. For the catalysts containing the lower Ti concentration (i.e., with residual SiOH groups), CHP exhibited significant higher epoxide selectivity than TBHP. The results suggest that the oxidant type had a stronger effect on the hydroperoxide decomposition rate (that occurred on the Si–O–H Bronsted acid site) than on the epoxidation rate (that occurred on the Si–O–Ti site), and that CHP had a significantly lower decomposition rate than TBHP. This is opposite to the results reported before for the hydroperoxide stability in the presence of liquid acid. When CHP was used as the oxidant, the rate of propylene epoxidation was found to be first-order with respect to the CHP concentration; the kinetic parameters were determined.

Keywords
Ti/SiO2 epoxidation catalysts; Propylene oxide; Chemical vapor deposition; Cumene hydroperoxide; tert-Butyl hydroperoxide; 1,2-Epoxyoctane
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Preparation of Ti/SiO2 catalysts by chemical vapor deposition method for olefin epoxidation with cumene hydroperoxide
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Publisher
Database: Elsevier - ScienceDirect
Journal: Applied Catalysis A: General - Volume 301, Issue 1, 10 February 2006, Pages 59–65
Authors
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Subjects
Physical Sciences and Engineering Chemical Engineering Catalysis
Get Full-Text Now
Don't Miss Today's Special Offer
Price was $35.95
You save - $31
Price after discount Only $4.95
100% Money Back Guarantee
Full-text PDF Download
Online Support
Any Questions? feel free to contact us