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Conversions of alcohols to the valued chemicals over metallo ZSM-5 catalysts
모용환,최영주,최혜정,박상언 한국공업화학회 2016 한국공업화학회 연구논문 초록집 Vol.2016 No.0
The Bio-Alcohols were converted into value added products such as BTX and C9 Aromatics over Metallo ZSM-5 catalysts. The mechanism of aromatization includes dehydration, oligomerization, dehydrogenation, cyclization, and cycloaromatization according to the literatures. Among these complicated multi-steps, dehydrogenation step seems to be the biggest hurdle, in which CO2 is expected to be consumed by removing hydrogen and helps to form aromatic chemicals via Reverse Water Gas Shift Reaction (RWGS) of intruded CO2 and by-produced hydrogen. Aromatization reaction was run over various metallo ZSM-5 catalysts which include Ga and Zn under CO2 stream and the enhancements in aromatics yields were observed when CO2 was flowed in the catalysts. More CO was formed when olefin/paraffin ratio increased as CO2 consumes H2 in between, and it was also confirmed in RWGS reaction.
Role of CO2 in Aromatization of Isobutanol/Isopropanol over Metal/ZSM-5
모용환,최영주,박상언 한국공업화학회 2015 한국공업화학회 연구논문 초록집 Vol.2015 No.0
The value added aromatics from low alkane and bioalcohol are evoking much interests as well as the demand of aromatics due to the configuration change on petrochemistry induced by the shake or natural gas. The industrial developed the Cyclar process has been suffered because of the problem of serious coke formation whereas the Ga-ZSM-5 catalyst has high activity for aromatization from low alkanes. When CO2 was co-fed with alcohols, the decreased deactivation rates within higher aromatics yield were maintained because of the role of the CO2 as a scavenger of hydrogen formed during dehydrocyclization after dehydration of alcohols. These phenomena seems to be mainly due to the role of CO2 by removing hydrogen and reducing the coke formation and sustaining of metallic oxidation states during the aromatization. The Zn or Ga species on ZSM-5 could be enhanced the aromatic yield and to decrease the coke formation by CO2. The isobutanol could be one of the useful sources which convert into aromatics over metal/ZSM-5. We calculated energy states of CO2 and bioalcohols adsorbed on surface of metal/ZSM-5.
Dehydrogenation of methanol over basic oxides supported silica catalysts
최혜정,모용환,서동우,박상언 한국공업화학회 2016 한국공업화학회 연구논문 초록집 Vol.2016 No.0
Methanol dehydrogenation was investigated over silica supported basic oxides such as Cs2O, BaO and MgO as basic catalyst. The support for the base oxide catalysts were platelet mesoporous silica, INC-2, having short 2D hexagonal diffusion channel for the impregnation of alkali and alkali earth metal precursors. Dehydrogenation of methanol with CO2 was studied in the process of transforming methanol to formaldehyde, as a result, the selectivity to formaldehyde was enhanced under CO2 atmosphere compared to under inert gas. CO2 played a role as a selectivity tuner for higher formaldehyde selectivity but passivator to sacrifice the conversion of methanol by partial poisoning of basic sites. On the other hand, CO2 could remove hydrogen species formed from methanol, which attributed to the enhanced formaldehyde selectivity and it was demonstrated by the Reverse Water-Gas Shift reaction activity.
Aromatization of light alkane over Metallo-HZSM-5 under CO₂
최영주,모용환,박상언 한국공업화학회 2015 한국공업화학회 연구논문 초록집 Vol.2015 No.0
The transformation of lower alkanes to aromatic hydrocarbons evoke a great interest in petrochemical industries in the view points of value addition to aromatics. Even though UOP/BP already commercialized so-called Cyclar Process from LPG fraction to aromatics, still it suffers from the large amount of coke formation and poor catalyst stability. Gaand Zn-ZSM-5 have been proved to show good aromatization activity as Lewis and Bronsted catalyst having MFI pore structure. However,active sites and mechanism are not well illustrated yet. Aromatization of alkane should accompany with dehydrogenation step not only at the initial stage but also cyclization into aromatics. Here, we are challenging to use CO2 as a vector gas to expect to reduce the coke formation through the reverse Boudouard reaction (C+CO2→2CO) and enhance the dehydrogenation activity through reverse water gas shift reaction (CO2+H2→CO+H2O).
Dehydrogenation of Alcohols over supported Basic Catalysts with CO₂
최혜정,모용환,서동우,박상언 한국공업화학회 2015 한국공업화학회 연구논문 초록집 Vol.2015 No.0
There has been an observation that CO2 could play roles as soft oxidant,promoter and enhancer. In those experiences, the hydrogen scavenger activity of CO2 over specific catalysts were proven and to be utilized in the aromatization from alcohols and lower hydrocarbons. This report will deal CO2 as another example of an enhancer for the dehydrogenation of alcohols over bimetallic catalysts. The designed catalysts were prepared on a platelet mesoporous silica, which has 2D hexagonal short channel, with basic oxide and/or metallic components like Ag, Cu, and Pd etc.. The catalytic behavior of alcohols with CO2 was studied over oxidation of various alcohols into corresponding aldehydes. And the selectivity on dehydrogenated products rather than dehydration products as well as CO2 effects were dependent on acid-basic properties of catalysts. CO2 played a role as an enhancer in the dehydrogenation activity of alcohols by removal of formed H2.
Role of CO2 on the propane to aromatics under the CO2 stream over Ga-Pd(Pt) HZSM-5 catalysts
최영주,박상언,모용환 한국공업화학회 2016 한국공업화학회 연구논문 초록집 Vol.2016 No.0
The conversion of light hydrocarbons into value added aromatic is one of the major challenges in the chemical industry. The key steps in this process are considered as the selective activation of C-H bond and the formation of C-C bonds through the dehydrogenation as an initial step. Such dehydrogenation step requires high temperature due to strong endothermic reaction, which subsequently gives serious coke problems. Thus, various metallo-zeolites such as Ga-ZSM-5 and Zn-ZSM-5 have been used for propane aromatization. In this work, Ga incorporated ZSM-5 was synthesized directly by one-pot synthesis method using microwave. And then, noble metals such as Pd or Pt were loaded by the impregnation. These synthesized catalysts were tested for propane aromatization under CO2 as a carrier gas. And it was observed CO2 participated in the RWGS reaction, which allowed to remove the formed hydrogen and attributed to higher activity and played a role as the hydrogen scavenger.
( Abhishek Burri ),모용환,박상언 한국공업화학회 2015 한국공업화학회 연구논문 초록집 Vol.2015 No.0
Oxidative dehydrogenation of propane was studied intensively over Cr and Vanadium based catalysts under CO2. In the dehydrogenation of propane with CO2, different oxide materials were investigated as catalysts. Cr promoted catalysts with different loadings of Cr has been synthesized using MW and applied in the oxidative dehydrogenation of propane to propylene using CO2 as soft oxidant. Loading of chromium ranged from 1 to 5 wt % showing very high surface area. The present catalysts showed high activity (20%) and stability even after 8 hours of reaction. The ratio of Cr6+ and Cr3+ are the main reasons for the high activity. Alkali and alkaline earth metal are proved to activate CO2. The basic nature of these promoters activate COx and enhance the stability of the catalysts. The present study is based on the promotional effect of alkali and alkaline earth metals. Alkali promotion has improved the CO2 conversion by altering the acid base properties of the catalyst and stabilizing the redox nature.
CO2 as promoter in the liquid-phase oxidation of aromatics
( Ranjit Kulkarni ),박상언,모용환,서동우 한국공업화학회 2016 한국공업화학회 연구논문 초록집 Vol.2016 No.0
In this study liquid phase solvent free catalytic oxidation of toluene was investigated over transition metal doped mesoporous carbon nitride (MCN) using O2 as a terminal oxidant. A series of metal-doped graphitic carbon nitride catalyst (Co-, Fe-, Mn-, (Co/Mn)-, and Ni-UF-MCN) were successfully synthesized by wet incipient impregnation method. It was found that the Fe (III)-doped graphitic UF-MCN catalyst was the most efficient catalytic system and exhibited a highest conversion of 6% with selectivity`s of (45%) Benzaldehyde and (45%) Benzoic acid. The Co-Presence of CO2 under analogous conditions showed enhancement in conversions (12%) and elevated selectivity`s (87%) towards Benzoic acid with minor product as Benzaldehyde. The quantification of the promotional effect of the synergism in the co-presence of CO2 was found to be 18-47 %. In situ FT-IR and GC studies revealed the CO formation of surface and the existence of CO in the gaseous mixture.