초록 ▼

1. 반응장치 제작2. 촉매의 제조 및 실험 1) 메탄의 이산화탄소 개질용 니켈 담지촉매 제조 2) 프로판용 이산화탄소 환원 촉매 제조. 3) 메틸포메이트 합성촉매의 제조(K-Fe/L Zeolite) 4) 메탄에 의한 이산화탄소 개질반응의 반응활성 조사 5) 프로판에 의한 이산화탄소 환원 반응 활성조사3. 촉매의 특성분석 1) 개질촉매의 EXAFS 분석 2) 메틸포메이트 합성촉매의 in-situ FT-IR 분석 3) SEM/TEM에 의한 개질촉매 분석 6) 개질촉매의 XPS 표면분석4. 이산화탄소 수소화에 의한 탄화

1. 반응장치 제작2. 촉매의 제조 및 실험 1) 메탄의 이산화탄소 개질용 니켈 담지촉매 제조 2) 프로판용 이산화탄소 환원 촉매 제조. 3) 메틸포메이트 합성촉매의 제조(K-Fe/L Zeolite) 4) 메탄에 의한 이산화탄소 개질반응의 반응활성 조사 5) 프로판에 의한 이산화탄소 환원 반응 활성조사3. 촉매의 특성분석 1) 개질촉매의 EXAFS 분석 2) 메틸포메이트 합성촉매의 in-situ FT-IR 분석 3) SEM/TEM에 의한 개질촉매 분석 6) 개질촉매의 XPS 표면분석4. 이산화탄소 수소화에 의한 탄화수소의 합성 1) Fischer-Tropsch 촉매로서 철촉매와 Mn, Co, Ni 성분의 합금(Bimetal) 형성에 의한 반응성 및 촉매 상태변화 관찰 2) 철촉매와 제올라이트 촉매의 물리적 혼성촉매의 적용에 의한 제올라이트측성에 따른 생성물 분포 및 특징 조사 3) K 첨가된 철촉매의 적용에 의한 표면 염기성도의 영향 관찰

Abstract ▼

Utilization of CO₂ as a carbon source might be one of the best way of diminishing the greenhouse effect induced via CO₂. There has been an increasing interest in the catalytic transformation of carbon dioxide into more usable or valuable compounds. Methanol route via hydrogenation of carbon dioxide

Utilization of CO₂ as a carbon source might be one of the best way of diminishing the greenhouse effect induced via CO₂. There has been an increasing interest in the catalytic transformation of carbon dioxide into more usable or valuable compounds. Methanol route via hydrogenation of carbon dioxide as well as the carbon dioxide reforming with methane into synthesis gas have been greatly interested as promising ways of CO₂ recycling chemistry due to their commercial availability and large treating capability. The growing importance of natural gas as feedstock, the demand of syngas having H₂/CO ratio of one, and the combination with steam reforming have stimulated the studies on the CO₂ reforming of methane. Group Ⅷ metal catalysts have been known to give high catalytic activities on this reforming reaction and give less carbon formation than nickel. However, nickel has been focused with special attention, because nickel is generally preferred as active component of the catalysts, which have been used for steam reforming with economic reasons. The diminution of the selectivity for CO, formed by reverse water-gas shift reaction has been considered as one of the challenging points in the methanol synthesis from CO₂ and H. One of the expected coproducts by application of this catalyst combination could be methylformate. In this sense, the activation of carbon monoxide together with carbon dioxide in the same reactor might help to increase the conversion of carbon dioxide, which would be limited in the case of methanol formation only. Catalytic fixation of carbon dioxide has been tried through the catalytic reduction with methane as well as hydrogen in order to convert into useful chemicals such as synthesis gas, hydrocarbons and oxygenates, respectively. Multifunctioning techniques were adopted by supporting nickel species with zeolite in the CO₂ reforming via solid-state reaction and by mixing K doped L type zeolite with the methanol synthesis catalyst, Cu/ZnO/Al₂O₃. It was shown that the incorporation of metallic components into zeolites via solid-state ion exchange exhibited excellent performance in catalytic reactions. Combination of methanol synthesis catalysts with solid acid or Fischer-Tropsch catalysts was proved to form dimethyl ether and hydrocarbons with improved conversion of CO₂ due to the consecutive conversions of methanol and CO. As a kind of such trial, we introduced K-Fe/L zeolite together with Cu/ZnO/Al₂O₃ catalyst in order to reduce the CO selectivity with the improved CO₂ conversion. A series of supported Ni and K-Ni-CaOx catalysts which were used in carbon dioxide reforming of methane (CDR) were prepared by solid-state reaction to make the efficient mixing of metal precursors and support and were calcined in air at 650℃ for 4hrs.. The main supports which have been used were ZSI(ZSM-5 having a boemite binder), ZSM-5, a-Al₂O₃, r-Al₂O₃, and boemite. ZSM-5 support having boehmite (ZSI) as a binder showed excellent activity as well as stability in the CO₂ reforming of methane when Ni was loaded together with alkaline promoters such as K and Ca. Deactivation and poor activity of supported nickel catalysts were resulted from sintering, phase transformation due to the solid-state reaction and coke formation depending on the supporting materials and promoters. Not only the dispersion of metallic nickel but also the reducibility of nickel oxide was strongly affected on the activity and stability. The highly interacted nickel species on calcium aluminate phase, which was supposed to be formed via solid-state reaction between boehmite and calcium promoter in ZSM-5 support, was ascribed to the high activity and stability in carbon dioxide reforming of methane. And this stable ZSI-supported K-Ni-CaOx catalyst was proved to be highly active and stable in carbon dioxide reduction by methane (CO₂ reforming of methane). Additionally, we suggested a method for CO₂ reduction by propane as an another hydrocarbon reductant, concurrently or separately producing more valuable products such as syngas and olefins. In addition, the hydrogenation of carbon dioxide to hydrocarbons over various catalysts was studied. As a base catalyst, iron catalysts prepared by impregnation and coprecipitation methods were adopted in the present study. Prepared iron catalyst was mixed with Mn, Ni, or Co and zeolites such as Y, Ferrierite, or ZSM-5 were used as the second components of hybrid system. Finally, potassium was added to iron catalyst to increase surface basicity. These catalysts were characterized by XRD, EDAX, Mossbauer, and Chemisorption methods, respectively. Catalytic investigations were carried out in a continuous fixed bed flow reactor. The mole ratio of used CO₂/H₂ mixed gas was 1:3. From the results on these, it was believed that hydrocarbons were synthesized from the carbon monoxide formed by the reverse water gas shift reaction (RWGS). On the other hand, combined metal catalysts ehanced the reducibility of iron and zeolite mixed catalysts not only promoted the conversion of CO₂ but also affected the hydrocarbon distributions. In the case of potassium added iron catalysts, activity of this reaction was singnificantly increased, but fastly deactivated. Therefore, it is a promising application to introduce Fischer-Tropsch reaction to our experimental systems and the product distribution can be controlled by these combinations. As an trial for the alleviation of chemical equilibrium limit in the hydrogenation of CO₂, K-doped Fe/L zeolite catalysts were mixed with methanol synthesis catalyst (Cu/ZnO/Al₂O₃) during the reaction of carbon dioxide with hydrogen. Formation of methylformate was confirmed. The K-Fe/L zeolite catalyst gave an role on the secondary activation of primary products, CO and methanol. This resulted not only in the enhancements of CO₂ conversion but also in the decrease of CO selectivity with the formation of methylformate. IR measurements made confirmation on the possibility of the methylformate formation from CO and methanol over K-Fe/L zeolite catalyst. The route for the formation of methylformate would be plausible via carbonylation of methanol. And both the activation of methanol and CO via potassium would play an important role on the carbonylation of methanol.

목차 Contents

• 제 1장 서 론...23
• 제 2장 이산화탄소 활용 연구현황...27
• 제 3장 실험...39
• 제 1절 촉매 제조...39
• 제 2절 반응활성조사...40
• 제 3절 개질 촉매 특성 조사...41
• 제 4절 흡착상태의 'in-situ'FT-IR 분석...43
• 제 4장 메탄에 의한 이산화탄소 환원 연구...45
• 제 1절 메탄의 개질 반응 고찰...45
• 1. 수증기 개질 반응...45
• 2. 산소 개질 반응...46
• 3. 메탄에 의한 이산화탄소 개질 반응...49
• 4. 메탄 개질촉매의 특성...50
• 제 2절 개질 촉매에 의한 이산화탄소 환원 고찰...53
• 1. 귀금속 개질 촉매...55
• 2. 니켈 담지촉매...61
• 3. 개질 반응기구...64
• 제 3절 니켈 촉매에 의한 이산화탄소 환원 반응...70
• 제 4절 니켈 담지촉매의 특성분석...88
• 1. X-선 회절 분석...88
• 2. 전자 현미경분석...95
• 3. 표면적 및 세공분석...98
• 4. TPR 분석...109
• 5. 니켈 담지촉매의 표면분석...110
• 6. EXAFS 분석...115
• 7. 니켈 촉매상에서의 반응 Scheme...129
• 제 5장 저급 탄화수소에 의한 이산화탄소 환원 연구...133
• 제 1절 저급 탄화수소에 의한 이산화탄소 환원 고찰...133
• 제 2절 프로판에 의한 이산화탄소 환원...135
• 제 6장 메틸 포메이트의 합성 연구...141
• 제 1절 메틸 포메이트 합성 고찰...141
• 제 2절 '메틸포메이트 합성촉매의 in-situ'FT-IR 분석...145
• 제 7장 결 론...157
• 참고문헌...160