Angewandte Chemie International Edition

Cover image for Vol. 56 Issue 36

Editor: Peter Gölitz, Deputy Editors: Neville Compton, Haymo Ross

Online ISSN: 1521-3773

Associated Title(s): Angewandte Chemie, Chemistry - A European Journal, Chemistry – An Asian Journal, ChemistryOpen, ChemPhotoChem, ChemPlusChem, Zeitschrift für Chemie

Press Release

Angew. Chem. Int. Ed. 2005, 44 (02), 271—273

No. 02/2005

One for all

A porous chromium oxide structure can adsorb volatile organic compounds and catalyze their decomposition to carbon dioxide

Volatile organic compounds (VOCs) like toluene or acetaldehyde are dangerous to the environment; they must thus be thoroughly removed from air discharged from industrial facilities. This is mostly done through adsorption, recovery, and subsequent catalytic combustion. Catalysts used for this are often oxygen compounds of the metals manganese, chromium, copper, or cobalt. For the first time, researchers in Japan have now developed a material that can do both: capture the VOCs and catalyze their oxidation to carbon dioxide.

A. K. Sinha and K. Suzuki have synthesized a three-dimensional cubic network of chromium oxide in which the chromium is in oxidation states ranging from +2 to +6 (Cr+6 ~ 4%). The average pore size is 7.9 nm, and the wall thickness is 13.3 nm; these lie in the range between micrometers (1 µm = one thousandth of a millimeter) and nanometers (1nm = one millionth of a millimeter). The material is thus designated mesoporous chromium oxide (mesos is the Greek word for middle, in between). The researchers produced this mesoporous structure by allowing chromium salts to slowly crystallize from a mixture of organic solvents in the presence of a special polymer, which acted as a template. Heating the material to temperatures above 400 °C then allowed them to completely remove the template.

Mesoporous chromium oxide is the first substance known which not only adsorbs VOCs at room temperature, but also catalyzes their decomposition under mild conditions. The amount of toluene was thus reduced by 52 % within 25 hours at room temperature, acetaldehyde by up to 94%. Raising the temperature to 85 °C destroyed 65 % of the toluene, above 280 °C 100 % of the toluene was removed. Heating to 350 °C leads to the oxidation of any residual VOCs and regeneration of the catalyst, which is then ready to be used again.

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