• Title, Summary, Keyword: Co catalyst

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Reaction Characteristics of WGS Catalyst with Fraction of Catalyst in a Batch Type Fluidized Bed Reactor (회분식 유동층 반응기에서 촉매함량 변화에 따른 WGS 촉매의 반응특성)

  • Ryu, Ho-Jung;Hyun, Ju-Soo;Kim, Ha-Na;Hwang, Taek-Sung
    • Transactions of the Korean hydrogen and new energy society
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    • v.22 no.4
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    • pp.465-473
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    • 2011
  • To find the optimum mixing ratio of WGS catalyst with $CO_2$ absorbent for SEWGS process, water gas shift reaction tests were carried out in a fluidized bed reactor using ShiftMax210 catalyst and sand (as a substitute for $CO_2$ absorbent). WGS catalyst content, gas velocity, and steam/CO ratio were considered as experimental variables. CO conversion increased as the catalyst content increased during water gas shift reaction. Variations of the CO conversion with the catalyst content were small at low gas velocity. However, those variations increased at higher gas velocity. Within experimental range of this study, the optimum operating condition(steam/CO ratio=3, gas velocity = 0.03 m/s, catalyst content=10 wt.%) to get high CO conversion and $CO_2$ capture efficiency was confirmed. Moreover, long time water gas shift reaction tests up to 20 hours were carried out for two cases (catalyst content = 10 and 20 wt.%) and we could conclude that the WGS reactivity at those conditions was maintained up to 20 hours.

Characterization of Enhanced CO Oxidation Activity by Alumina Supported Platinum Catalyst

  • Jo, Myung-Chan
    • Journal of Environmental Science International
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    • v.18 no.10
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    • pp.1071-1077
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    • 2009
  • A novel pretreatment technique was applied to the conventional Pt/alumina catalyst to prepare for the highly efficient catalyst for the preferential oxidation of carbon monoxide in hydrogen-rich condition. Their performance was investigated by selective CO oxidation reaction. CO conversion with the oxygen-treated Pt/Alumina catalyst increased remarkably especially at the low temperature below $100^{\circ}C$. This result is promising for the normal operation of the proton exchange membrane fuel cell (PEMFC) without CO poisoning of the anode catalyst. XRD analysis results showed that metallic Pt peaks were not observed for the oxygen-treated catalyst. This implies that well dispersed small Pt particles exist on the catalyst. This result was continued by high resolution transmission electron microscopy (HRTEM) analysis. Consequently, it can be concluded that highly dispersed Pt nanoparticles could be prepared by the novel pretreatment technique and thus, CO conversion could be increased considerably especially at the low temperatures below $100^{\circ}C$.

Effect of Pre-treatment Method on Reactivity of WGS Catalyst for SEWGS System (SEWGS 시스템을 위한 WGS 촉매의 반응성에 미치는 수소 전 처리 방법의 영향)

  • Ryu, Hojung;Park, Jihye;Lee, Dongho;Shun, Dowon;Rhee, Youngwoo
    • Transactions of the Korean hydrogen and new energy society
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    • v.25 no.4
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    • pp.355-363
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    • 2014
  • Thermal shock or overheating of WGS catalyst for SEWGS system during hydrogen pre-treatment can cause reactivity decay of the catalyst. To select appropriate pre-treatment condition, temperature profiles of catalyst bed (or outside fluidized particle bed of bed insert) during pre-treatment were measured and then CO conversions of those catalysts during WGS reaction were also measured and compared. Drastic overheating of catalyst took place when we reduce catalyst at fixed bed condition and these catalysts showed low CO conversion during WGS reaction. On the contrary, there was no overheating of catalyst at fluidized bed condition not only physical mixing case but also bed insert case. Spring type bed insert showed acceptable CO conversion even at low WGS content. Consequently, feasibility of high CO conversion without decay of reactivity of catalyst and holding the WGS catalyst inside the SEWGS reactor as tablet shape were confirmed using spring type bed insert.

CO Conversion Characteristics of WGS Catalysts for SEWGS System (SEWGS 시스템을 위한 WGS 촉매들의 CO 전환 특성)

  • Ryu, Hojung;Park, Jihye;Lee, Dongho;Park, Jaehyeon;Bae, Dalhee
    • Transactions of the Korean hydrogen and new energy society
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    • v.26 no.2
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    • pp.96-104
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    • 2015
  • Reactivity of commercial WGS catalyst(MDC-7) and four new catalysts(RMC-3, PC-73, PC-67SU, PC-59) manufactured with various compositions by Korea Electric Power Research Institute(KEPCO RI) were compared to select suitable WGS catalyst for SEWGS system. Steam/CO ratio, gas velocity, flow rates of syngas, and temperature were considered as operating variables. As a result, MDC-7 catalyst showed the highest CO conversion and RMC-3 catalyst showed also high CO conversion. Therefore, MDC-7 and RMC-3 catalysts were selected as applicable catalysts. However, PC-73 catalyst showed low CO conversion at low temperature($200^{\circ}C$) but showed good reactivity at high temperature($225{\sim}250^{\circ}C$), and therefore, PC-73 catalyst was selected as applicable catalyst for high temperature operation. Continuous operations up to 24 hours for those three catalysts(MDC-7, RMC-3, PC-73) were conducted to check reactivity decay of catalysts. All three catalysts maintained their original reactivity.

Hydrolysis Reaction of NaBH4 Using Activated Cabon Supported Co-B/C, Co-P-B/C Catalyst (활성탄 담지 Co-B/C, Co-P-B/C 촉매를 이용한 NaBH4 가수분해 반응)

  • Oh, Sohyeong;Kim, Youkyum;Bae, Hyojune;Kim, Dongho;Byun, Younghwan;Ahn, Ho-Geun;Park, Kwon-Pil
    • Korean Chemical Engineering Research
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    • v.56 no.5
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    • pp.641-646
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    • 2018
  • Sodium borohydride, $NaBH_4$, shows a number of advantages as hydrogen source for portable proton exchange membrane fuel cells (PEMFCs). Properties of $NaBH_4$ hydrolysis reaction using activated carbon supported Co-B/C, Co-P-B/C catalyst were studied. BET surface area of catalyst, yield of hydrogen, effect of $NaBH_4$ concentration and durability of catalyst were measured. The BET surface area of carbon supported catalyst was over $500m^2/g$ and this value was 2~3 times higher than that of unsupported catalyst. Hydrogen generation of activated carbon supported catalyst was more stable than that of unsupported catalyst. The activation energy of Co-P-B/C catalyst was 59.4 kJ/mol in 20 wt% $NaBH_4$ and 14% lower than that of Co-P-B/FeCrAlloy catalyst. Catalyst loss on activated carbon supported catalyst was reduced to about 1/3~1/2 compared with unsupported catalyst, therefore durability was improved by supporting catalyst on activated carbon.

The Influence of a Second Metal on the Ni/SiC Catalyst for the Methanation of Syngas

  • Song, Lanlan;Yu, Yue;Wang, Xiaoxiao;Jin, Guoqiang;Wang, Yingyong;Guo, XiangYun
    • Korean Chemical Engineering Research
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    • v.52 no.5
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    • pp.678-687
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    • 2014
  • The catalytic performance of silicon carbide supported nickel catalysts modified with or without second metal (Co, Cu and Zn) for the methanation of CO has been investigated in a fixed-bed reactor using a feed consisting of 25% CO and 75% $H_2$ without any diluent gas. It has been found that the introduction of Co species can clearly improve the catalytic activity of Ni/SiC catalyst, whereas the addition of Cu or Zn can result in a significant decrease in the catalytic activity. The characterizations by means of XRD, TEM, XPS, CO-TPD and $H_2$-TPR indicate that the addition of Co could decrease the particle size of active metal, increase active sites on the surface of methanation catalyst, improve the chemisorption of CO and enhance the reducibility of methanation catalysts. Additionally, the special interaction between Co species and Ni species is likely favorable for the dissociation of adsorbed CO on the surface of catalyst, and this may also contribute to the high activity of 5Co-Ni/SiC catalyst for CO methanation reaction. For 5Cu-Ni/SiC catalyst and 5Zn-Ni/SiC catalyst, Cu and Zn species could cover partial nickel particles and decrease the chemisorption amount of CO. These could be responsible for the low methanation activity. In addition, a 150h stability test under 2 MPa and $300^{\circ}C$ showed that 5Co-Ni/SiC catalyst was very stable for CO methanation reaction.

The Effect of K Promoter on Ni-Co (Bimetallic) Catalyst for Dry Methane Reforming

  • Dharmasaroja, Nichthima;Phongaksorn, Monrudee;Tungkamani, Sabaithip;Ratana, Tanakorn;Sornchammi, Thana
    • International Journal of Advanced Culture Technology
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    • v.3 no.2
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    • pp.110-117
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    • 2015
  • 10 wt% (Ni-Co) catalysts with different Ni and Co content : 10%Ni, 9%Ni1%Co, 7%Ni3%Co, 5%Ni5%Co, 3%Ni7%Co, and 10%Co; were prepared using sol-gel method followed by incipient wetness impregnation method. To investigate the catalytic activity including the stability, dry methane reforming were demonstrated over the pelletized catalysts at $620^{\circ}C$ under atmospheric pressure in a $CH_4:CO_2:N_2$ feedstock for 360 min. The results showed that bimetallic catalysts with the Co content equal to or greater than 3% were more stable than monometallic catalysts (10%Ni and 10%Co). The temperature programmed hydrogenation interpreted that the additional of Co into Ni catalyst improved the carbon resistance from methane cracking. Promoted this type of bimetallic catalyst using 1wt% K (trimetallic catalyst) prevented the carbon formation on the catalyst. The temperature programmed desorption of $CO_2$ indicated that this trimetallic catalyst has a greater number of strong basic sites. Moreover, the appearance of K lowered the number of weak basic sites and decreased the conversion of methane by 12 %.

Preparation of CuO-CeO2 mixed oxide catalyst by sol-gel method and its application to preferential oxidation of CO (졸-겔법에 의한 CuO-CeO2 복합 산화물 촉매의 제조 및 CO의 선택적 산화반응에 응용)

  • Hwang, Jae-Young;Hahm, Hyun-Sik
    • Journal of the Korean Applied Science and Technology
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    • v.34 no.4
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    • pp.883-891
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    • 2017
  • For the preferential oxidation of CO contained in the fuel of polymer electrolyte membrane fuel cell (PEMFC), CuO-$CeO_2$ mixed oxide catalysts were prepared by the sol-gel and co-precipitation methods to replace noble metal catalysts. In the catalyst preparation by the sol-gel method, Cu/Ce ratio and hydrolysis ratio were changed. The catalytic activity of the prepared catalysts was compared with the catalytic activity of the noble metal catalyst($Pt/{\gamma}-Al_2O_3$). Among the catalysts prepared with different Cu/Ce ratios, the catalyst whose Cu/Ce ratio was 4:16 showed the highest CO conversion (90%) and selectivity (60%) at $150^{\circ}C$. As the hydrolysis ratio was increased in the catalyst preparation, surface area increased, and catalytic activity also increased. The highest CO conversions with the CuO-$CeO_2$ mixed oxide catalyst prepared by the co-precipitation method and the noble metal catalyst (1wt% $Pt/{\gamma}-Al_2O_3$) were 82 and 81% at $150^{\circ}C$, respectively, whereas the highest CO conversion with the CuO-$CeO_2$ mixed oxide catalyst prepared by the sol-gel method was 90% at the same temperature. This indicates that the catalyst prepared by the sol-gel method shows higher catalytic activity than the catalysts prepared by the co-precipitation method and the noble metal catalyst. From the CO-TPD experiment, it was found that the catalyst having CO desorption peak at a lower temperature ($140^{\circ}C$) revealed higher catalytic activity.

Characteristics of Hydrolysis Reaction Using Unsupported Catalyst at High Concentration of NaBH4 Solutions (고농도 NaBH4 수용액에서 비담지 촉매의 가수분해 반응 특성)

  • Lee, Hye-Ri;Na, Il-Chai;Park, Kwon-Pil
    • Korean Chemical Engineering Research
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    • v.54 no.5
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    • pp.587-592
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    • 2016
  • Sodium borohydride, $NaBH_4$, shows a number of advantages as hydrogen source for portable proton exchange membrane fuel cells (PEMFCs). Properties of $NaBH_4$ hydrolysis reaction using unsupported Co-P-B Co-B, catalyst at high concentration $NaBH_4$ solution were studied. In order to enhance the hydrogen generation yield at high concentration of $NaBH_4$, the effect of catalyst type, $NaBH_4$ concentration and recovery of condensing water on the hydrogen yield were measured. The yield of hydrogen evolution increased as the boron ratio increased in preparation process of Co-P-B catalyst. The hydrogen yield decreased as the concentration increased from 20 wt% to 25 wt% in $NaBH_4$ solution during hydrolysis reaction using 1:5 Co-P-B catalyst. Maximum hydrogen yield of 96.4% obtained by recovery of condensing water and thinning of catalyst pack thickness in reactor using Co-P-B with Co-B catalyst and 25 wt% $NaBH_4$ solution.

Cycloaddition of carbon dioxide with propylene oxide using zeolitic imidazolate framework ZIF-23 as a catalyst

  • Ryu, Hyeongseok;Roshan, Roshith;Kim, Moon-Il;Kim, Dong-Woo;Selvaraj, Manickam;Park, Dae-Won
    • Korean Journal of Chemical Engineering
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    • v.34 no.3
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    • pp.928-934
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    • 2017
  • Zeolitic imidazolate framework ZIF-23 was prepared and used as catalyst for the solventless synthesis of cyclic carbonate from $CO_2$ and propylene oxide with or without TBAB co-catalyst. ZIF-23 catalysts were prepared by a solvothermal or microwave method and they were characterized by various physicochemical techniques such as XRD, FT-IR, BET, TGA, and FE-SEM. The effects of reaction parameters such as temperature, reaction time, $CO_2$ pressure, and co-catalyst on the reactivity of catalyst were investigated. ZIF-23 was recyclable up to four times without any considerable loss of its initial activity. Reaction mechanism containing the role of ZIF-23 with TBAB co-catalyst was also proposed.