HWAHAK KONGHAK, Vol.26, No.5, 526-534, October, 1988
Zeolite 촉매를 이용한 Methyl tert-Butyl Ether의 합성
Methyl tert-Butyl Ether Synthesis on Zeolite Catalysts
초록
HZSM-5, HZSM-11, H-Mordenite 및 HY형 zeolite를 촉매로 사용하여 기상 MTBE 합성실험을 수행하였으며, zeolite 촉매의 종류 및 반응조건에 따른 MTBE 생성관계를 연구하였다. 각 촉매들은 pyridine을 흡착시켜 TPD 및 IR법으로 산점의 세기와 종류를 측정하였으며, 촉매의 산성도 및 세공구조적 특성에 연관지어 MTBE에 대한 선택성을 검토하였다.
HZSM-5상에서는 methanol의 탈수에 따른 DME의 생성이 관찰되기는 하였으나, MTBE에 대하여 92 %에 가까운 선택도를 보였다. H-Mordenite에 있어서도 DME와 MTBE가 생성되었지만 MTBE에 대한 전환율과 선택도는 ZSM-5 계열보다 현저하게 낮았으며, 반응시간이 길어짐에 따라 심한 활성감퇴가 일어났다. HY의 경우에는 i-C4H8의 중합에 따른 C8-olefin의 생성률이 높았으며, H-Mordenite와 마찬가지로 반응시간이 길어짐에 따라 촉매의 비활성화가 관찰되었다.
MTBE에 대한 전환율과 선택도는 i-C4H8/CH3OH의 몰비가 커짐에 따라 증가되었으며, i-C4H8의 HZSM-5 세공내부로의 확산이 상대적으로 큰 저항을 받음을 알 수 있었다. 온도가 상승됨에 따라 MTBE의 분해반응이 앙진되었으며, 모든 경우에 80 ℃의 반응온도가 합성에 적합하였다.
HZSM-5상에서는 methanol의 탈수에 따른 DME의 생성이 관찰되기는 하였으나, MTBE에 대하여 92 %에 가까운 선택도를 보였다. H-Mordenite에 있어서도 DME와 MTBE가 생성되었지만 MTBE에 대한 전환율과 선택도는 ZSM-5 계열보다 현저하게 낮았으며, 반응시간이 길어짐에 따라 심한 활성감퇴가 일어났다. HY의 경우에는 i-C4H8의 중합에 따른 C8-olefin의 생성률이 높았으며, H-Mordenite와 마찬가지로 반응시간이 길어짐에 따라 촉매의 비활성화가 관찰되었다.
MTBE에 대한 전환율과 선택도는 i-C4H8/CH3OH의 몰비가 커짐에 따라 증가되었으며, i-C4H8의 HZSM-5 세공내부로의 확산이 상대적으로 큰 저항을 받음을 알 수 있었다. 온도가 상승됨에 따라 MTBE의 분해반응이 앙진되었으며, 모든 경우에 80 ℃의 반응온도가 합성에 적합하였다.
Vapor phase reaction of methanol with iso-butylene to form methyl tert-butyl ether（MTBE） han been conducted using HZSM-5, HZSM-11, H-Mordenite and HY catalysts. The effects of catalyst typers and reaction conditions on the products distribution have been examined.
Determination of acid type and strength of each catalyst used in this experiment were carried out by means of temperature programmed desorption （TPD） of pyridine adsorbed catalysts and IR analysis.
The relation of the MTBE selectivities to the acidities and pore characteristics of the zeolite catalysts were studied.
On HZSM-5, a small amount of dimethylether （DME） was formed via methanol dehydration, but selectivity to MTBE was close to 92 %. DME and MTBE were also formed over H-Mordenite, but selectivity to the latter was considerably lower than HZSM-5. In addition, its severe deactivation occurred upon prolonged use.
Significant amount of C8-olefin was formed in addition to MTBE with HY which also deactivated quickly.
As iso-butylene/methanol ratio increased, the conversion and selectivity to MTBE have been greatly enhanced indicating the restricted access of iso-butylene to the HZSM-5 pore structure.
The decomposition of MTBE becomes important as the reaction temperature is raised, and shows adequate temperature for the MTBE synthesis to be about 80 ℃.
Determination of acid type and strength of each catalyst used in this experiment were carried out by means of temperature programmed desorption （TPD） of pyridine adsorbed catalysts and IR analysis.
The relation of the MTBE selectivities to the acidities and pore characteristics of the zeolite catalysts were studied.
On HZSM-5, a small amount of dimethylether （DME） was formed via methanol dehydration, but selectivity to MTBE was close to 92 %. DME and MTBE were also formed over H-Mordenite, but selectivity to the latter was considerably lower than HZSM-5. In addition, its severe deactivation occurred upon prolonged use.
Significant amount of C8-olefin was formed in addition to MTBE with HY which also deactivated quickly.
As iso-butylene/methanol ratio increased, the conversion and selectivity to MTBE have been greatly enhanced indicating the restricted access of iso-butylene to the HZSM-5 pore structure.
The decomposition of MTBE becomes important as the reaction temperature is raised, and shows adequate temperature for the MTBE synthesis to be about 80 ℃.