Diffusion Controlled Alkylation of Aromatic Compounds in Cation-Exchanged ZSM-5 Zeolites

Chon, Hak-Ze,Lee, Kyung-Yul,Park, Dong-Ho,Ahn, Byoung-Joon Korean Chemical Society 1991 Bulletin of the Korean Chemical Society Vol.12 No.6

Using uniform flat plate-like samples of ZSM-5 zeolites, diffusion coefficients were measured volumetrically for the diffusion of xylene, ethyltoluene and diethylbenzene by direct measurement of sorption rate. Toluene disproportionation over H(100)-, K(72)-and Cs(82)-ZSM-5 at 773 K and toluene methylation, toluene ethylation and ethylbenzene ethylation over Cs(75)-ZSM-5 at 623 K were carried out. The selective formation of para xylene during the toluene disproportionation, presumably due to the increased tortuosity over Cs-ZSM-5, could be explained by smaller diffusion coefficient in Cs-ZSM-5 than in K-and H-ZSM-5. The para selectivity increased in the order; toluene methylation < toluene ethylation < ethylbenzene ethylation. As the chain length of the alkyl substituent in dialkylbenzenes is increased, the para selectivity of the products was improved. It may be attributed to the differences in the ratios of diffusion coefficient of para products to that of ortho ones. Diffusion coefficient of m-xylene was about 1 order of magnitude smaller than that of o-xylene.

산화아연에서의 $C_3H_6$의 산화반응

전학제,한종수,Hak Ze Chon,Chong Soo Han 대한화학회 1981 대한화학회지 Vol.25 No.2

산화아연에서 흡착산소종과 프로필렌의 상호작용을 EPR과 TPD를 사용 연구했다. 흡착산소종 $O_2^-$는 $25^{\circ}C$에서 프로필렌과 작용, g=1.96의 반응중간체를 생성했는데 이는 $200^{\circ}C$이상에서 $H_2$, CO와 $CO_2$, $CH_4$등으로 분해되었다. 흡착산소종 $O^-$는 프로필렌과 상호작용, g=2.008의 중간체 및 완전산화물인 $CO_2$, $H_2O$ 등을 생성했다. The reactions of adsorbed oxygen species, $O_2^-$ and $O^-$, with propylene on ZnO were studied by EPR spectroscopy and temperature programmed desorption technique. Propylene interacts with adsorbed $O_2^-$ at $25^{\circ}C$ and the surface intermediate was decomposed to CO, $H_2$, $CO_2$ and $CH_4$ by raising the temperature above $200^{\circ}C$, while $O^-$ gave the products of complete oxidation, $CO_2$ and $H_2O$ above $300^{\circ}C$.

Structural Transition of A-Type Zeolite: Molecular Dynamics Study

Song, Mee-Kyung,Chon, Hak-Ze Korean Chemical Society 1993 Bulletin of the Korean Chemical Society Vol.14 No.2

Molecular dynamics (MD) calculations were carried out in order to investigate the effect of MD cell size to predict the melting phenomena of A-type zeolite. We studied two model systems: a pseudocell of $(T_2O_4Na)_n$, (L= 12.264 $^{\AA}$, N= 84) and a true-cell of (SiAlO$_4Na)_n$. (L= 24.528 $^{\AA}$, N= 672), where T is Si or Al. The radial and bond angle distribution functions of T(Si, Al)-O-T(Si, Al) and diffusion coefficients of T and O were reported at various temperatures. For the true-cell model, the melting temperature is below 1500 K and probably around 1000 K, which is about 600-700 K lower than the pseudocell model. Although it took more time (about 30 times longer) to obtain the molecular trajectories of the true-cell model than those of the pseudocell model, the true-cell model gave more realistic structural transition for the A-type zeolite, which agrees with experiment.

The Effect of Oxygen Adsorption on the Depth of Space Charge Region on ZnO $(10{\bar{1}}0)$

Han, Chong-Soo,Jun, Jin,Chon, Hak-Ze Korean Chemical Society 1992 Bulletin of the Korean Chemical Society Vol.13 No.1

The apparent depth of space charge region on the ZnO $(10{\bar{1}}0)$ surface in chemisorption of oxygen has been estimated from the capacitance of two contacting faces. When the sample (donor concentration: $2.4{\times}10^{22}\;m^{-3}$) was evacuated at 773 K for 1 hr the depth reached to 40-100 ${\AA}$ depending on sample assembly. Admission of oxygen to the sample resulted in an increase of the depth to 3600 ${\AA}$ where the increment was greater at higher oxygen pressure between 6.6-1600 $N/m^2$. Admission of CO to the sample previously exposed to oxygen yields a decrease in the depth. The results of the measurement support that oxygen is adsorbed as an acceptor on ZnO $(10{\bar{1}}0)$.

연구발표논문초록 ( 촉매 / 반응공학 (1) ) : 광음향분광법 ( PAS ) 을 이용한 CoAPO - 5 와 CoZSM - 5 분자체의 분광학적 연구

이경열 (학),전학제 (정),( Kyoung Yul Lee,HaK ze Chon ) 한국화학공학회 1989 추계학술발표회 Vol.- No.-

ZSM-5 제올라이트 촉매상에서의 메탄올로부터 탄화수소 합성반응

박상언,전학제,Sang Eon Park,Hak Ze Chon 대한화학회 1981 대한화학회지 Vol.25 No.2

$SiO_2$/$Al_2O_3$ 비가 높은 제올라이트 ZSM-5를 합성하여 메탄올의 탄화수소로의 전환반응을 조사하였다. 메탄올이 전환되어 올레핀, 파라핀, 시클로파라핀 및 방향족화합물이 생성되었으며 특히 방향족 화합물에 대한 큰 선택성을 보여 주었고 1,3,5-trimethylbenzene의 크기정도에 제한된 형상선택성 촉매작용임을 알 수 있었다. 수소형태(HZSM-5)가 활성이 커, 메탄올이 탈수되어 일어나는 잇단 복잡한 반응들이 산촉매반응이 주임을 보여 주었다. ZSM-5와 구조가 유사한 mordenite와 3차원구조를 지닌 faujasite 촉매에서의 메탄올의 반응으로 구조적 영향과 TPD실험에 의한 산점분포를 비교한 결과 메탄올로부터 방향족화합물에 이르기까지의 탄화수소 합성에서의 ZSM-5 제올라이트의 촉매작용은 높은 실리카함량에 기인한 강한 산성과 교차하는 세공관 구조에 의한 분자체 효과에 의한 것으로 볼 수 있다. The conversion of methanol to hydrocarbons has been studied over synthetic ZSM-5 zeolite catalyst having high silica to alumina ratio. The conversion products were olefins, paraffins, cycloparaffins, and aromatics, and the catalyst showed especially high selectivity toward the formation of aromatics. The catalyst showed the shape-selectivity and the size of molecules in the product was limited approximately to the size of 1,3,5-trimethylbenzene. Hydrogen form(HZSM-5) was more active, indicating reactions following the dehydration of methanol seemed to be mainly catalyzed by acid sites. Comparison of the reaction characteristics and acid site distribution of the ZSM-5 catalyst with those of mordenite and faujasite type catalysts suggests that cross-linked pore channel structure and the strong acidity of the ZSM-5 catalyst are primarily responsible for the selective formation of aromatics over this catalyst.

모더나이트 촉매상에서 트리메틸벤젠의 반응

안병준,전학제,Byoung Joon Ahn,Hak Ze Chon 대한화학회 1981 대한화학회지 Vol.25 No.3

알루미늄을 추출시킨뒤 양이온 교환에 의해 세공크기를 조절한 모더나이트 촉매상에서 트리메틸벤젠의 이성질화 반응에 대한 형상선택성을 조사했다. 반응온도가 높아짐에 따라 동종간 주고 받기 반응은 크게 증가했고 이성질화 반응에는 큰 변화가 없었다. 1,2,4-트리메틸벤젠의 반응에서 반응시간이 경과함에 따라 1,3,5-트리메틸벤젠과 동종간 주고 받기 생성물이 급격히 감소하였다. 반응생성물의 분포, 특히 이성질화 생성물의 분포로 미루어보아 Ba-모더나이트 촉매의 유효세공의 지름은 약 8.1과 8.6${\AA}$사이값을 갖는 것으로 생각되었다. The reactions of trimethylbenzenes were investigated over dealuminated, cation-exchanged mordenite catalysts. Higher reaction temperature favored the formation of disproportionation products. In the reaction of 1,2,4-trimethylbenzene, the formation of 1,3,5-trimethylbenzene and the disproportionation products decreased sharply with reaction time. The product distribution, especially the distribution of trimethylbenzenes, suggests that the effective pore diameter of Ba-exchanged dealuminated mordenite catalysts lies somewhere between 8.1 and 8.6${\AA}$.

ZSM-5 촉매상에서 메탄올의 전환반응, 반응특성과 안정성

박상언,전학제,Sang Eon Park,Hak Ze Chon 대한화학회 1981 대한화학회지 Vol.25 No.3

형상 선택성 ZSM-5 제올라이트 촉매상에서 메탄올로부터 $C_2-C_{10}4</TRX>의 탄화수소 형성을 조사하였다. 메탄올로 부터 dimethylether를 거쳐 생성되는 $C_2-C_5$의 올레핀들이 ZSM-5의 강한 산점에서 고리화 반응등에 의하여 방향족 화합물이 많이 포함된 탄화수소화합물로 전환된다고 생각된다. 메탄올의 전환반응에 대한 ZSM-5 촉매의 높은 활성과 활성저하에 대한 안정성은 특유의 교차되는 세공관구조와 소수성에 기인하는 것으로 보인다. The formation of $C_2-C_{10}$ hydrocarbons from methanol over shape-selective ZSM-5 zeolite catalysts is studied. It seems that $C_2-C_5$ olefins formed from methanol via dimethylether are transformed further to higher hydrocarbons containing higher concentration of aromatics by the acid sites of ZSM-5. Unique cross linked channel structure and its hydrophobicity seems to be mainly responsible for its high activity of ZSM-5 catalyst for the conversion of methanol.

Measurement of The Depth of Depletion Layer in Oxidation of $C_2H_4$ on ZnO

Jun, Jin,Han, Chong-Soo,Chon, Hak-Ze Korean Chemical Society 1994 Bulletin of the Korean Chemical Society Vol.15 No.7

펜타실 제올라이트의 합성에 관한 연구

안병준,전학제,Ahn, Byung-Joon,Chon, Hak-Ze 대한화학회 1988 대한화학회지 Vol.32 No.2

ZSM-5, ZSM-8, ZSM-11 및 실리카라이트를 포함하는 펜타실 제올라이트들을 여러가지 유기양이온과 실리카졸을 사용하여 합성하고 반응온도, 교반, 숙성시간 등 합성조건을 변화시키므로서 균일한 크기와 모양을 갖는 결정을 얻었다. TEA-OH(수산화 사에틸암모늄), TPA-OH, TBA-OH 및 Choline이 유기양이온으로 사용되었으며 콜로이달 실리카(Snowtex)를 실리카원으로 사용했다. 합성 실험은 $2{\ell}$ 압력 반응기 (parr제품)와 자체 제작된 자석식 반응기를 사용하였으며, 반응물 조성(실리카/알루미나 비), 반응온도 등이 펜타실 제올라이트 합성의 중요한 인자임을 알았다. Pentasil zeolites, including ZSM-5, ZSM-8, ZSM-11 and silicalites, were synthesized using various organic cations. Synthesis run was carried out in a Parr pressure reactor of $2{\ell}$ capacity and a self-constructed reactor with a magnetic stirring system. The reactant materials used are colloidal silica (Snowtex), sodium aluminate, sodium chloride, TEA, TPA, TBA, Choline and water. The composition of starting materials and the reaction temperature were found to be important factors for the synthesis of uniform pentasil zeolites.