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Language: korean

Conflict of Interest: In relation to this article, we declare that there is no conflict of interest.

Publication history: Received October 21, 2003
Accepted December 15, 2003

This is an Open-Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/bync/3.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

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Pd/titania 촉매에 의한 아세틸렌 Cyclotrimerization

Cyclotrimerization of Acetylene on Pd/titania Catalyst

정용화 이태진 김기석^†

Yong-Hwa Jung Tae-Jin Lee Ki-Seok Kim^†

영남대학교 응용화학공학부, 712-749 경북 경산시 대동 214-1

School of Chemical Engineering and Technology, Yeungnam University, 214-1, Dae-dong, Gyeongsan, Gyeongbuk 712-749, Korea

Korean Chemical Engineering Research, February 2004, 42(1), 33-37(5), NONE Epub 21 April 2004

Abstract

Pd/titania 촉매에 의한 아세틸렌 cyclotrimerization의 반응성과 생성물 분포의 변화를 상압조건하의 373 K에서 flow reaction 실험에 의해서 연구하였다. 주요 생성물로서 에틸렌과 벤젠이 얻어졌으나 시간이 경과함에 따라서 촉매의 피독으로 인하여 아세틸렌 전화율이 급격히 감소하였다. 일정한 반응기체 유속(공간속도 4,000 hr^-1)에서 아세틸렌 농도를 50, 25, 12.5 vol%로 감소시켰을 경우 벤젠 생성량은 감소하였으나 촉매의 피독은 완화되었다. 이세틸렌 농도 변화에 대한 벤젠 생성량의 비교에 의해서 벤젠 생성반응이 아세틸렌 농도에 대해 1차 반응임을 확인하였다. 또한 일정한 아세틸렌 농도(25 vol%)에 대하여 공간속도를 4,000 hr^-1에서 6,000 hr^-1로 증가시켰을 경우 촉매의 피독이 완화되었으며 벤젠 생성량도 증가하였다. Flow reaction에 의한 아세틸렌 cyclotrimerization에 있어서 촉매 피독을 완화시키고 벤젠 수율을 증대시키기 위해서는 반응기체 흐름의 아세틸렌 농도와 유속의 최적화가 필요해 보인다. 본 연구에 있어서 palladium-titania 계면의 oxygen anion vacancies와 환원된 titania 표면이 종전의 연구자들 보다 100 K낮은 온도에서의 벤젠 생성에 기여한 것으로 추정된다.

Cyclotrimerization of acetylene was studied by means of atmospheric flow reaction at 373 K on Pd/titania catalyst to investigate variations of catalytic reactivity and product distribution. While ethylene and benzene were obtained as the major products, rapid decrease in acetylene conversion resulted from catalyst poisoning with the lapse of reaction time. For a fixed flow rate (space velocity 4,000 hr^-1), as acetylene concentrations decreased from 50 to 25, to 12.5 vol%, benzene yields decreased, whereas catalyst poisoning was attenuated. Comparison of benzene evolution signals from the variation of acetylene concentrations showed that the rate of benzene formation is first-order in acetylene pressure. In addition, for a fixed concentration (25 vol%) of acetylene, as space velocity increased from 4,000 to 6,000 hr^-1, benzene yields also increased and catalyst poisoning was attenuated. Optimization of acetylene concentration and flow rate may be necessary to accomplish the attenuation of catalyst poisoning as well as enhancement of benzene yield from acetylene cyclotrimerization by flow reaction. It can be deduced from this study that oxygen anion vacancies at palladium-titania interface and reduced titania made contributions toward catalytic activity for benzene formation at the temperature 100 K lower than those reported by previous researchers.

Keywords

Cyclotrimerization of Acetylene Pd/titania Catalyst Oxygen Anion Vacancies Benzene Yield

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