Catalytic hydrodechlorination of chlorocarbons. 2: Ternary oxide supports for catalytic conversions of 1,2-dichlorobenzene
- Univ. of Iowa, Iowa City, IA (United States). Dept. of Chemistry
Ternary oxides of Ti-Zr-Al and Ti-Zr-Si were prepared by coating commercial Al{sub 2}O{sub 3} and SiO{sub 2} with a THF solution of Ti(OPr{sup i}){sub 4} and Zr(OPr{sup 1}){sub 4} under controlled conditions. Nitrogen adsorption and X-ray powder diffraction indicate that the structure of the base supports, Al{sub 2}O{sub 3} and SiO{sub 2}, were not significantly altered upon coating and that TiO{sub 2} and ZrO{sub 2} were quite uniformly spread on them. The acid resistance of alumina was found to be increased upon coating. Palladium supported catalysts, Pd/TiZrAlO{sub x}, Pd/TiZrSiO{sub x}, Pd/TiO{sub 2}, Pd/ZrO{sub 2}, Pd/SiO{sub 2}, and Pd/Al{sub 2}O{sub 3} were prepared to evaluate the ternary oxides relative to the component single oxide supports. Palladium dispersion was determined using hydrogen chemisorption and the catalysts were evaluated for hydrodechlorination of 1,2-dichlorobenzene. The experimental runs were carried out in a microflow reactor system at atmospheric pressure, in the gas phase. The catalysts were oxidized and then reduced, prior to reaction. The kinetic studies showed that the ternary oxide-based catalyst, Pd/TiZrAlO{sub x} exhibited an improved stability and activity much higher than the arithmetic sum of the activities of the component single oxide based palladium catalysts. Comparison of the specific activities of the catalysts expressed as TOF, indicate that the observed differences in activity may be related to the chemical nature of the supports. The best catalyst had an initial specific activity of 16.6 s{sup {minus}1}. The authors observed that the pretreatment of the catalyst has a profound effect on its stability and activity. Also, the experimental results indicated that the major factors of the catalyst deactivation are agglomeration of palladium particles and HCl poisoning. Prospects for optimization of these catalysts are discussed in light of the results of this work.
- Sponsoring Organization:
- USDOE, Washington, DC (United States)
- OSTI ID:
- 672474
- Journal Information:
- Journal of Catalysis, Journal Name: Journal of Catalysis Journal Issue: 1 Vol. 179; ISSN 0021-9517; ISSN JCTLA5
- Country of Publication:
- United States
- Language:
- English
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