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Y-제올라이트 촉매상에서의 톨루엔과 메탄올로부터 자일렌 합성에 관한 연구
A Study on the Formation of Xylene from Toluene and Methanol over Y-zeolite Catalysts
HWAHAK KONGHAK, August 1984, 22(4), 173-180(8), NONE
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Abstract
Y-제올라이트 촉매상에서 p-자일렌을 생성키 위하여 톨루엔을 메탄올로 알킬화 반응을 시켰다. 실험은 상압하에서 고정상 촉매를 이용하여 수행하였고, 자일렌 이성체의 선택성은 반응온도, 공간속도, 반응물의 비율 등 실험조건에 따라 현저한 차이를 나타내었다. 반응 최적온도인 350 ℃에서 열역학적 평형상태는 약 20 %의 p-자이렌을 혼합 자일렌 속에 함유하고 있는데 반하여, 본 실험의 경우, p-자일렌은 47 %의 조성을 이루었다. HX촉매는 높은 선택성을, HY촉매는 높은 활성을 나타내었고, HM촉매와 Si-Al 촉매는 낮은 활성을 나타내었다. 최적 반응조건은, 반응온도는 350 ℃, 톨루엔/메탄올의 몰비는 2, 공간속도는 0.48 l/g-cat/hr이었다. 상대적으로 높은 반응온도에서는 Y-제올라이트 촉매상에서 열역학적 평형치와 유사한 자이렌 혼합물을 생성하였다. 주 생성물은 자일렌, 트리메틸벤젠 및 벤젠이었으며, 기체크로마토그래피에 의하여 분석하였다. 자일렌 생성에 미치는 조촉매의 영향을 알아보기 위하여 BF2와 WO3를 주촉매에 첨가시켰다. HY촉매에 담지된 BF3의 양이 2 wt%일 때 p-자일렌의 수율은 8.6 %에서 13.7 %로 증가하였으며, WO3의 경우, WO3의 함량이 5 wt%일 때 8.6 %에서 13.8 %로 증가하였다. 또 p-자일렌의 생성에 Brönsted 산이 미치는 영향을 알아보기 위하여 HCl을 HFeY 촉매에 첨가시켰다. HCl의 함량이 메탄올 양의 6 wt%일 때, p-자일렌의 수율은 15.7 %에서 19.7 %로 증가하였다.
Toluene has been alkylated with methanol over Y-zeolite catalysts to produce p-xylene. The experiment was carried out continuously over fixed bed catalysts under atmospheric pressure. The selectivity for a specific xylene isomer was demonstrated to undergo a remarkable change depending on the experimental conditions such as temperature, space velocity, and reactant ratio in the feed. At thermodynamic equilibrium at 350 ℃ of optimum reaction temperature, the xylene mixture contains about 20 % of p-xylene, while in this study the product mixture consisted of 47 % of p-xylene. It has been found that HX-zeolite has a high selectivity and HY-zeolite a high activity, whereas both HM-zeolite and silica-alumina have low activities The optimum reaction conditions were as follows ; reaction temperature of 350 ℃, toluene/methanol mole ratio of 2, and space velocity of 0.48 l/gr-cat/hr. At relatively high reaction temperatures, Y-zeolite catalysts produced the mixture of xylene which composition corresponds closely to thermodynamic equilibrium values. The main products were xylene, trimethylbenzene, and benzene. The products were analyzed by gas chromatography. As a promoter, BF3 and WO3 were added to the main catalysts in order to understand the effect of supports on the formation of xylene. When the content of BF3 supported on HY-zeolite was 2 wt%, the yield of p-xylene was increased from 8.6 % to 13.7 %. For WO3, with 5 wt% of WO3 the yield of p-xylene was increased from 8.6 % to 13.8 %. In order to know the effect of Brönsted acid on the yield of p-xylene, HCl was added to HFeY catalyst. As the content of p-xylene was 6 wt% with respect to methanol, the yield of p-xylene was increased from 15.7 % to 19.7 %.