Heterogeneous photocatalytic oxidation of trichloroethylene and toluene mixtures in air: Kinetic promotion and inhibition, time-dependent catalyst activity

Journal Article · Sun Sep 15 04:00:00 EDT 1996 · Journal of Catalysis

DOI:https://doi.org/10.1006/jcat.1996.0299· OSTI ID:508453

Luo, Yang; Ollis, D F ^[1]

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1. North Carolina State Univ., Raleigh, NC (United States)

Photocatalyzed degradation of grace level trichloroethylene (TCE) and toluene in air were carried out over near-UV-illuminated titanium dioxide (anatase) powder in a flow reactor using a residence time of about 5-6 ms. Concentration ranges for TCE and toluene were 0-800 mg/m{sup 3}. TCE photooxidation was very rapid under there experimental conditions, and {approximately} 100% conversion was achieved for TCE concentration examined up to 753 mg/m{sup 3} as a single air contaminant. Initial photodegradation rates for toluene in humidified air were fitted by a Langmuir-Hinshelwood rate form. Toluene photooxidation sole contaminant rates were of the same order of magnitude as reported previously for m-xylene and acetone. No significant intermediates were detected by GC/FID during TCE or toluene photooxidation reactions. Humidification had significant influence: Toluene photooxidation rate increases with the water concentration up to about 1650 mg/m{sup 3} 20% relative humidity and decreases thereafter. The presence of sufficient TCE (225-753 mg/m{sup 3}) promoted the toluene photooxidation reaction rate to achieve 90-100% toluene conversion in 5.6 ms. When feed toluene levels measured below {approximately} 90 mg/m{sup 3}. Higher toluene feed levels {open_quotes}quenched{close_quotes} this TCE promotion effect and also depressed TCE conversion very strongly, but the toluene conversion fell just to the toluene-only levels observed in single contaminant experiments. Photooxidation kinetics of TCE and toluene mixtures in air are thus shown to exhibit strong promotion and inhibition behavior vs that expected from the single-species kinetic degradation data. 42 refs. 9 figs., 2 tabs.

• OSTI ID: 508453
• Journal Information: Journal of Catalysis, Journal Name: Journal of Catalysis Journal Issue: 1 Vol. 163; ISSN 0021-9517; ISSN JCTLA5
• Country of Publication: United States
• Language: English

Related Subjects

40 CHEMISTRY
54 ENVIRONMENTAL SCIENCES
CATALYSTS
CATALYTIC EFFECTS
CHEMICAL REACTION KINETICS
CHLORINATED ALIPHATIC HYDROCARBONS
HETEROGENEOUS CATALYSIS
OXIDATION
PHOTOCHEMICAL REACTIONS
TITANIUM OXIDES
TOLUENE