HWAHAK KONGHAK, Vol.26, No.3, 261-271, June, 1988
ZSM-5 및 Silicalite-I의 합성(I)
Synthesis of ZSM-5 and Silicalite-I(I)
초록
Zeosil77과 sodium silicate 溶液을 silica源으로 사용하여 ZSM-5 및 Silicalite-I을 水熱合成하였으며, 反應基質의 組成, 熟成時間, 反應溫度 및 反應時間 등이 結晶生成에 미치는 영향을 검토하였다.
ZSM-5는 反應基質의 組成이 酸化物의 몰比로서 Na2O/ SiO2=0.05∼0.2, SiO2/Al2O3=30∼∞, H2O/Na2O=200∼600 및 TPA+/SiO2=0.12인 領域에서 高純度로 生成되었다. ZSM-5型 zeolite의 合成에 있어서는 室溫熟成時間이 2일까지 길어짐에 따라 誘導期間 및 結晶化時間이 단축되고, 生成된 結晶의 크기도 작아짐을 알 수 있었다.
Silica源으로서 微粉末인 Zeosil만을 사용한 경우보다 sodium silicate solution에 Zeosil을 보충한 때가 더욱 빠른 結晶化速度를 나타내었다.
Sodium silicate와 Zeosil을 混用하여 ZSM-5（SiO2/Al2O3=68）를 合成하였을 때와 Silicalite-I을 合成할 때의 核生成過程 및 結晶化過程에서 요하는 活性化에너지는 각각 54, 22 KJ/mole(ZSM-5) 및 40, 15 KJ/mole(Silicalite-I)이었으며, Zeosil만을 silica源으로 사용했을 경우의 活性化에너지는 각각 60, 38 KJ/mole(ZSM-5) 및 40, 26 KJ/mole(Silicalite-I) 이었다.
ZSM-5는 反應基質의 組成이 酸化物의 몰比로서 Na2O/ SiO2=0.05∼0.2, SiO2/Al2O3=30∼∞, H2O/Na2O=200∼600 및 TPA+/SiO2=0.12인 領域에서 高純度로 生成되었다. ZSM-5型 zeolite의 合成에 있어서는 室溫熟成時間이 2일까지 길어짐에 따라 誘導期間 및 結晶化時間이 단축되고, 生成된 結晶의 크기도 작아짐을 알 수 있었다.
Silica源으로서 微粉末인 Zeosil만을 사용한 경우보다 sodium silicate solution에 Zeosil을 보충한 때가 더욱 빠른 結晶化速度를 나타내었다.
Sodium silicate와 Zeosil을 混用하여 ZSM-5（SiO2/Al2O3=68）를 合成하였을 때와 Silicalite-I을 合成할 때의 核生成過程 및 結晶化過程에서 요하는 活性化에너지는 각각 54, 22 KJ/mole(ZSM-5) 및 40, 15 KJ/mole(Silicalite-I)이었으며, Zeosil만을 silica源으로 사용했을 경우의 活性化에너지는 각각 60, 38 KJ/mole(ZSM-5) 및 40, 26 KJ/mole(Silicalite-I) 이었다.
ZSM-5 and Silicalite-I were synthesized hydrothermally using Zeosil 77 and sodium silicate solution as silica sources, and the effects of reactants composition, aging time, reaction temperature and reaction time on the zeolite crystallization were investigated.
It was established that the oxides molar ratio of substrates resulting ZSM-5 type zeolite in high purity were as follows;
Na2O/SiO2=0.5-0.2, SiO2/Al2O3=30-∞, H2O/Na2O=200-600, TPA+ /SiO2=0.12.
For the ZSM-5 type zeolites, the induction period, and reaction time and the obtained crystal size were found to decrease progressively as the aging time is increased up to 2 days. At the same time, the higher rates of crystallization were obtained when sodium silicate solution in conjunction with Zeosil was used as the silica source than Zeosil alone.
The activation energies for the nucleation and those for the crystal growth step of ZSM-5 and Silicalite-I were 54.22 KJ/mole（for ZSM-5） and 40, 15 KJ/mole (for Silicalite-I) when sodium silicate solution blended with Zeosil was used as the silica source. On the other hand, the activation energies using Zeosil as the silica source were 60, 38 KJ/mole(for ZSM-5) and 40, 26 KJ/mole (for Silicalite-I), respectively.
It was established that the oxides molar ratio of substrates resulting ZSM-5 type zeolite in high purity were as follows;
Na2O/SiO2=0.5-0.2, SiO2/Al2O3=30-∞, H2O/Na2O=200-600, TPA+ /SiO2=0.12.
For the ZSM-5 type zeolites, the induction period, and reaction time and the obtained crystal size were found to decrease progressively as the aging time is increased up to 2 days. At the same time, the higher rates of crystallization were obtained when sodium silicate solution in conjunction with Zeosil was used as the silica source than Zeosil alone.
The activation energies for the nucleation and those for the crystal growth step of ZSM-5 and Silicalite-I were 54.22 KJ/mole（for ZSM-5） and 40, 15 KJ/mole (for Silicalite-I) when sodium silicate solution blended with Zeosil was used as the silica source. On the other hand, the activation energies using Zeosil as the silica source were 60, 38 KJ/mole(for ZSM-5) and 40, 26 KJ/mole (for Silicalite-I), respectively.