| 학회 | 한국화학공학회 |
| 학술대회 | 1998년 봄 (04/24 ~ 04/25, KOEX) |
| 권호 | 4권 1호, p.177 |
| 발표분야 | 촉매/반응공학 |
| 제목 | MFI 구조를 갖는 ferrisilicate의 제조와 시클로헥산 산화반응에서 촉매로서의 반응성 |
| 초록 | Ferrisilicate can be directly synthesized and iron cation can be located in the tetrahedral framework sites of a molecular sieve structure. Four samples of MFI typeferrisilicates (Si/Fe = 300) molecular sieves were synthesized hydrothermally atautogeneous pressure. The final pH used in this synthesis varied from 8 to 11. The pHof the gel mixture during the synthesis affects the reaction kinetics, the yield and thesize, morphology and chemical composition of the crystals. We observed that thecatalysts with the same Si/Fe ratio in the synthesis did not always display identicalcatalytic activity in the cyclohexane oxidation reaction. This was due to structuraldifferences in the crystalline solids resulting from the different synthesis conditionsemployed.The EPR spectra of FeMFI samples were examined. The individual signals are due tothe following species: framework Fe3+ in tetrahedral site for g = 4.3, ion exchange siteFe3+ for g = 2.0, and precipitated Fe3+ species on the surface and the channel for g =2.1, respectively. In addition, we consider around g = 2.3 signal as the extraframeworkclustered ferric ions. The relative intensity of the spectra at g = 4.3 increased withdecreasing the pH of gel mixture. Accordingly, the relative intensity of the g = 2.0compared to the g = 4.3 is smaller in the high pH samples.FeMFI samples were used as catalysts for the oxidation of cyclohexane under mildconditions. FeMFI-1 sample with the higher amount of tetrahedral site of Fe3+ showshigher conversion of cyclohexane oxidation. The concentration of the framework Fe3+in the FeMFI-1 and FeMFI-2 is much higher than the remaining two samples thus thetetrahedral Fe3+ of the framework is responsible for the active species in thecyclohexane oxidation. This interpretation is good agrement with the result of EPRsignal. |
| 저자 | 염영훈, 남상성, 김성보, 이규완 |
| 소속 | 한국화학(연) |
| 키워드 | molecular seive; iron; ferrisilicate; cyclohexane; catalyst; EPR |
| 원문파일 | 초록 보기 |
