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니켈 담지 촉매에서 에틸벤젠의 수소화 알킬기 제거 반응

Hydrodealkylation Reacion of Ethylbenzene over Nickel-Supported Catalyst

HWAHAK KONGHAK, October 1986, 24(5), 343-349(7), NONE
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Abstract

니켈 또는 니켈-텅스텐 담지 촉매에서 에틸벤젠의 수소화 알킬기 제거반응을 유통식 반응기를 이용하여 조사하였다. 니켈만 담지된 촉매에서는 350 ℃에서 톨루엔만 주로 생성되었으며 반응온도가 높아지면 전화율과 벤젠의 선택도가 높아졌다. 450 ℃이상에서는 방향족 고리까지 수소화 분해되어 메탄만 생성되었으며 이러한 경향은 m-크실렌에서도 동일하였다. 니켈과 텅스텐을 같이 담지시킨 촉매에서는 550 ℃에서도 방향족 고리의 수소화 분해가 억제되어 벤젠의 선택도가 높아졌으나 텅스텐의 담지 몰비가 커지면 전화율은 크게 감소하였다. 담지된 니켈과 텅스텐의 Auger 스펙트럼에서 관찰된 전자에너지는 담지 몰비에 따라 달라졌으며, 100-190 ℃에서 측정한 벤젠의 가역 흡착열은 텡스텐의 함량이 많아지면 감소되는 현상을 보였다. 텅스텐 첨가에 따른 벤젠의 선택도향상은 니켈에 대한 텅스텐의 상호작용으로 벤젠고리의 흡착강도가 약해져 수소화 분해반응이 억제되는데 기인하는 것으로 생각되었다.
The hydrodealkylation reaction of ethylbenzene over nickel or nickel-tungsten supported catalysts was studied in a flow reactor system. Toluene was a major product at 350 ℃ over nickel supported catalyst and the conversion of ethylbenzene and the selectivity of benzene increased at higher temperature. Above 450 ℃, methane hydrocracked from aromatic ring was only produced. The product distributions of m-xylene with reaction temperature were similar to those of ethylbenzene. The hydrocracking of aromatic ring of ethylbenzene was restrained at 550 ℃ over nickel-tungsten supported catalyst. When tungsten was added to nickel supported catalyst, decrease of catalytic activity and increase of selectivity for benzene were observed. The electron energies of supported nickel and tungsten, observed in Auger electron spectra were varied with the composition of supported material. The reversible adsorption heat of benzene determined at the range of 100-190 ℃ decreased with increasing the content of tungsten. The increase in the selectivity for benzene due to the co-impregnation of tungsten might be explained in terms of the reduction of catalytic activity for hydrocracking reaction with decrease in the adsorption strength of benzene on the catalysts by the interaction between supported nickel and tungsten.

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