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HWAHAK KONGHAK,
Vol.40, No.2, 139-145, 2002
Vol.40, No.2, 139-145, 2002
티타늄 함유 ZSM-5 촉매의 에탄올에 의한 톨루엔 알킬화 반응 특성
Alkylation of Toluene with Ethanol over a Ti-ZSM-5 Catalyst
티타늄 함유 ZSM-5(Ti-ZSM-5) 촉매 상에서 톨루엔의 알킬화 반응을 수행하여 촉매의 활성 및 생성물 분포를 이온교환 H-ZSM-5 및 Mg 함침 촉매의 성능과 비교하였고, 촉매 반응에 미치는 제반 인자들의 영향을 살펴보았다. 톨루엔의 에탄올에 의한 알킬화 반응은 약 350 ℃의 반응온도에서 ethyltoluene, 그리고 이성체 중에서 p-ethyltoluene의 선택도가 가장 높게 나타났으며, 부반응을 억제하기 위해서는 높은 톨루엔/에탄올 몰비와 짧은 접촉시간이 필요하였다. Ludox 실리카를 이용하여 제조한 Ti-ZSM-5(Ti=1%) 촉매는 순수한 ZSM-5 촉매에 비하여 높은 para 선택도를 나타내었으며, 반응이 진행되는 동안 탄소누적에 의한 비활성화가 느리게 진행되었다. NH3-TPD 분석결과 Ti-ZSM-5 촉매는 산점의 세기와 수가 순수한 ZSM-5에 비하여 현저히 감소하였고, p-ethyltoluene의 선택도 향상에 기여하였다고 판단된다.
Performances of Ti-ZSM-5 catalysts for toluene alkylation using ethanol were evaluated and compared with those of H-ZSM-5 or Mg-modified ZSM-5. Investigation on the influences of reaction parameters on the alkylation reaction was also conducted. The highest ethyltoluene and p-ethyltoluene, among the isomers, selectivities were obtained ca 350 ℃, and higher
toluene/ethanol molar ratio and shorter contact time were necessary in order to suppress the side reactions. Ti-ZSM-5(1% Ti) prepared using Ludox silica showed enhanced para-selectivity compared to pure ZSM-5 and more resistant toward deactivation caused by carbonaceous deposit. According to the NH3-TPD analysis, acid strength and amounts of acid sites of ZSM-5
were significantly reduced by the incorporation of titanium into the zeolite framework, which were responsible for the improved p-ethyltoluene yield.
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