분말의 Zr(OH)4를 (NH4)2CrO4수용액에 함침시킨 후 공기 중에 소성하여 지르코니아에 담지된 산호크롬 촉매를 제조하였다. 제조된 CrOx/ZrO2 촉매상에 n-hexane을 반응시켜 촉매성질을 연구한 결과 크롬의 산화상태가 +6인 chromate 형태로 지르코니아 표면에 존재할 때는 강한 산점이 생성되어 n-hexane의 cracking 반응에 촉매활성을 나타내었다. 그러나 많은 양의 Cr+6 종은 반응중에 n-hexane에 의하여 환원되어 Cr3+종으로 변화되었으며 Cr3+종은 n-hexane을 탈수소 고리화시켜 benzene을 생성하는 반응에 활성점으로 작용하였다. 환원된 Cr3+종은 O2로 처리하면 다시 Cr6+종으로 되고 따라서 산회된 촉매는 cracking반응에 활성을 나타내었다.
Chromium oxide/zirconia catalysts were prepared by dry impregnation of powdered Zr(OH)4 with aqueous solution of (NH4)2CrO4 followed by calcining in air. The catalytic properties of prepared catalysts were investigated by reacting n-hexane as test material over catalysts. As a consequence it was found that Cr6+ species(as chromate) existing on the surface of catalyst was responsible for the formation of strong acid site and the cracking catalytic activity of n-hexane. However, the Cr6+ species was reduced to Cr3+ species during the catalytic reaction of n-hexane and the reduced Cr3+ species was acitive for the benzene formation due to the dehydrocylization of n-hexane. The reduced Cr3+ species was reoxidized by treatment with O2 and consequently the reoxidized catlyst exhibited catalytic activity for the cracking reaction of n-hexane.
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