Artificial sunlight and ultraviolet light induced photo-epoxidation of propylene over V-Ti/MCM-41 photocatalyst.

Van-Huy Nguyen,Hsunling Bai,Shawn D Lin,Jeffrey Chi-Sheng Wu

doi:10.3762/bjnano.5.67

Van-Huy Nguyen, Hsunling Bai + Show 2 more

Open Access

https://doi.org/10.3762/bjnano.5.67

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Abstract

The light irradiation parameters, including the wavelength spectrum and intensity of light source, can significantly influence a photocatalytic reaction. This study examines the propylene photo-epoxidation over V-Ti/MCM-41 photocatalyst by using artificial sunlight (Xe lamp with/without an Air Mass 1.5 Global Filter at 1.6/18.5 mW·cm−2) and ultraviolet light (Mercury Arc lamp with different filters in the range of 0.1–0.8 mW·cm−2). This is the first report of using artificial sunlight to drive the photo-epoxidation of propylene. Over V-Ti/MCM-41 photocatalyst, the propylene oxide (PO) formation rate is 193.0 and 112.1 µmol·gcat−1·h−1 with a PO selectivity of 35.0 and 53.7% under UV light and artificial sunlight, respectively. A normalized light utilization (NLU) index is defined and found to correlate well with the rate of both PO formation and C3H6 consumption in log–log scale. The light utilization with a mercury arc lamp is better than with a xenon lamp. The selectivity to PO remains practically unchanged with respect to NLU, suggesting that the photo-epoxidation occurs through the same mechanism under the conditions tested in this study.

Highlights

It is agreed that light, especially its wavelength spectrum and intensity, is a crucial factor for efficient photocatalysis
How the light energy can be effectively utilized in a heterogeneous photocatalysis process is under debate, and both the intensity and the exposure time to light irradiation need to be considered [4,10]
We previously proposed that the titanium in V-Ti/MCM-41 should be Ti4+ with a tetrahedral coordination [17]

Summary

Introduction

It is agreed that light, especially its wavelength spectrum and intensity, is a crucial factor for efficient photocatalysis. We compared the photo-epoxidation over V-Ti/ MCM-41 photocatalyst with different wavelengths (365, 320–500 and 250–400 nm) and different light intensities in the range of 0.1–0.8 mW·cm−2.

Results

Conclusion