• 한국수소및신에너지학회논문집
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• 제33권4호
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• pp.451-461
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• 2022

CFD analysis including optimization process was conducted to design shell and tube CO₂ methanation reactor cooling system. The high-pressure saturated water flowed into the cooling system and was evaporated by heat flux from reacting tubes. The optimization process decided the gap between tubes and reactor diameter to satisfy objective functions related to temperature. The results showed that the gap and diameter reduced about 30% and 3.6% respectively. Averaged surface temperature satisfied the target value and the min-max deviation was minimized.

• 한국수소및신에너지학회논문집
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• 제34권3호
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• pp.316-326
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• 2023

Development of carbon-neutral fuel production technologies to solve climate change issues is progressing worldwide. Among them, methane can be produced through the synthesis of hydrogen produced by renewable energy and carbon dioxide captured through a CO₂ methanation reaction, and the fuel produced in this way is called synthetic methane or e-methane. The CO₂ methanation reaction can be conducted via biological or thermochemical methods. In this study, a 30 Nm³/h thermochemical CO₂ methanation process consisting of an isothermal reactor and an adiabatic reactor was used. The CO₂ conversion rate and methane concentration according to the temperature measurement results at the center and outside of the adiabatic reactor were analyzed. The gas flow into the adiabatic reactor was found to reach equilibrium after about 1.10 seconds or more by evaluating the residence time. Furthermore, experimental and analysis results were compared to evaluate performance of the reactor.

• 청정기술
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• 제19권2호
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• pp.156-164
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• 2013

본 연구에서는 등온반응기와 단열반응기로 구성된 0.25 MW 메탄합성 파일롯 공정 실험을 통한 운전 특성을 분석하였다. 등온반응기는 메탄합성 반응을 통해 발생하는 열을 포화수의 유량과 압력을 통해 강제적으로 제어할 수 있는 반응기로 등온반응기와 단열반응기를 조합할 경우 기존 단열반응기만으로 구성된 메탄합성 공정에 비해 반응기 개수를 줄일 수 있다. 또한 합성가스 재순환이 불필요하기 때문에 단열반응기 조합으로 구성된 메탄합성 공정에서 비용의 약 15~20%를 차지하는 재순환 압축기를 제거할 수 있다. 등온반응기로 유입되는 합성가스의 $H_2$/CO 비가 3보다 낮은 경우에는 튜브에 충진된 촉매에 탄소 침적 현상이 일어나 반응기의 차압이 증가하였으며, $H_2$/CO 비가 3으로 공급되는 경우에는 탄소 침적 현상이 일어나지 않고 메탄합성 반응이 안정적으로 유지되어 CO 전환율 99% 이상, $CH_4$선택도 97% 이상, $CH_4$생산성 최대 $695ml/h{\cdot}-cat$를 얻을 수 있었다.

• 공업화학
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• 제31권3호
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• pp.323-327
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• 2020

이산화탄소 메탄화 공정 적용을 위해 저온에서 우수한 활성을 나타내는 Ni/CeO_2-X의 반응 특성을 조사하였다. 지지체인 CeO_2-X는 Ce(NO₃)₃를 400 ℃에서 열처리하여 획득하였으며, 촉매는 함침법으로 제조되었다. 실험의 운전 변수로써 반응기 내부 압력, 유입가스 중 산소, 메탄, 황화수소의 조성 및 반응 온도에 대하여 수행하였다. Ni/CeO_2-X를 이용한 이산화탄소 메탄화 반응에서 압력이 1 bar에서 3 bar로 증가함에 따라 CO₂ 전환율은 25% 이상 증가하였으며, 낮은 반응 온도에서 증가폭이 크게 나타났다. 유입가스 중 산소와 메탄은 촉매의 CO₂ 전환율을 최대 16, 4%씩 감소시켰으며, 산소와 메탄의 농도가 높아질수록 CO₂ 전환율의 감소율이 증가하는 경향을 나타내었다. 또한 황화수소는 촉매의 CO₂ 전환율을 최대 7% 감소시켰으며 촉매의 비활성화를 야기하였다. 본 연구의 결과들은 이산화탄소의 메탄화 공정 기초 자료로 유용하게 사용될 수 있을 것이다.

• 한국수소및신에너지학회논문집
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• 제30권1호
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• pp.14-20
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• 2019

The power to gas (P2G) is one of the energy storage technologies that can increase the storage period and storage capacity compared to the existing battery type. One of P2G technologies produces hydrogen by decomposing water from renewable energy (electricity) and the other produces $CH_4$ by reacting hydrogen with $CO_2$. The objective of this study is the reaction of $CO_2$ methanation which synthesized methane by reacting carbon dioxide and hydrogen. The effect of $CO_2$ conversion and $CH_4$ selectivity on reaction temperature, pressure, and methane contents over 40% Ni catalyst was mainly investigated throughout this study. As a result, the activity of this catalyst appeared to be the highest in $CH_4$ yield at around $400^{\circ}C$ and the selectivity of $CH_4$ increased with increasing reaction pressure. The methane content was not significantly influenced below 3% of all componets. As the space velocity increases from 10,000 to 30,000/hr, the $CO_2$ conversion rate tends to decrease.

• 한국수소및신에너지학회논문집
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• 제22권2호
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• pp.249-256
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• 2011

In this study, the Ni-based catalysts for the production of synthetic natural gas were prepared by various preparation methods such as the co-precipitation, precipitation, impregnation and physical mixing methods. The ranges of the reaction conditions were the temperatures of 250~$350^{\circ}C$, $H_2$/CO mole ratio of 3.0, the pressures of 1 atm and the space velocity of 20000 $ml/g_{-cat{\cdot}}{\cdot}h$. It was found that the catalyst prepared by precipitation method had higher CO conversion than the catalyst prepared by co-precipitation method. While the catalyst prepared by precipitation method had the formation of NiO structure, the catalyst prepared by co-precipitation method had the formation of $NiAl_2O_4$ structure. It was confirmed that Ni-based catalyst prepared by the physical mixing method had the lowest CO conversion because it was deactivated by the production of $Ni_3C$ during the methanation. As a result, it was shown clearly that Ni-based catalysts prepared by impregnation method expressed the highest catalytic activity in CO methanation.

• 한국수소및신에너지학회논문집
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• 제31권5호
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• pp.419-428
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• 2020

The kinetics of direct methanation over activated charcoal-supported molybdenum catalyst at 30 bar was studied in a cylindrical fixed-bed reactor. When the temperature was not higher than 400℃, the CO conversion increased with increasing temperature according to the Arrhenius law of reaction kinetics. While XRD and Raman analysis showed that Mo was present as Mo oxides after reduction or methanation, TEM and XPS analysis showed that Mo₂C was formed after methanation depending on the loading of Mo precursor. When the temperature was as high as 500℃, the CO conversion was dependent not only on the Arrhenius law but also on the catalyzed reaction by nanoparticles, which came off from the reactor and thermocouple by metal dusting. These nanoparticles were made of Ni, Fe, Cr and alloy, and attributed to the formation of carbon deposit on the wall of the reactor and on the surface of the thermocouple. The carbon deposit consisted of amorphous and disordered carbon filaments.

• 청정기술
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• 제24권2호
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• pp.99-104
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• 2018

본 연구에서는 합성천연가스(synthetic natural gas, SNG)를 생산하기 위한 공정 개발을 위해 RIST-IAE에서 제안한 공정의 4차 반응기에 대하여 합성가스($H_2/CO_2$)를 이용하여 메탄화 반응을 수행하였다. 실험의 조건은 온도, 압력, 공간속도 등을 변화시켰으며, 이때 $CO_2$ 전환율, $CH_4$ 선택도, 반응 후 $H_2$의 농도에 대해 고찰하였다. 그 결과 $CO_2$ 메탄화반응에 의한 $CH_4$의 선택도는 공간속도가 낮을수록, 그리고 압력이 높을수록 증가하였다. 한편, 온도의 경우에는 $320^{\circ}C$에서 최대 값을 보였다. 이러한 결과로부터 SNG 공정에 적합한 4차반응기의 최적 조건을 얻을 수 있었다.

• 공업화학
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• 제4권2호
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• pp.365-372
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• 1993

양이온이 교환된 Y형 제올라이트에 담지된 니켈촉매상에서 이산화탄소의 메탄화반응을 상압과 $200{\sim}550^{\circ}C$의 온도범위, 수소와 이산화탄소의 몰비가 4인 조건에서 수행하였다. Y형 제올라이트에 이온교환된 양이온에 따라 이산화탄소와 니켈간의 결합력의 차이를 보였으며, TPD(Temperature-programmed desorption) 결과 Ni/NaY>Ni/MgY>Ni/HY 순으로 결합력이 작아지는 것으로 나타났고, TPSR(Temperature-programmed surface reaction)의 결과로부터 이산화탄소와 니켈의 결합력이 강할 때 반응의 활성이 좋음을 알 수 있었다. 니켈의 환원온도가 높을수록 반응활성이 증가하는 것으로 보아 이산화탄소의 메탄화반응은 환원된 니켈금속입자가 커질수록 유리한 것으로 나타났고, 니켈의 담지량이 3.3wt%일 때 최대의 활성을 나타내었다. 반응온도 조건의 전범위에서 일산화탄소가 부생성물로 생성되었으며, 반응물과 촉매의 접촉시간이 길어질수록 생성물질중의 일산화탄소가 감소하는 것으로 미루어 이산화탄소가 일산화탄소를 경유하여 메탄으로 전환됨을 알 수 있었다. $410{\sim}450^{\circ}C$의 온도범위에서 메탄의 생성속도는 이산화탄소의 분압에 대하여 3.3에서 -0.5 지수승에 비례하고 수소의 분압에 대하여 1.4에서 3.6 지수승에 비례하며, 이산화탄소와 수소가 경쟁적으로 니켈에 흡착함을 알 수 있었다.

• 한국수소및신에너지학회논문집
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• 제32권5호
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• pp.388-400
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• 2021

Power to gas (P2G) is one of the energy storage technologies that can increase the storage period and storage capacity compared to the existing battery type. One of P2G technology produces hydrogen by decomposing water from renewable energy (electricity) and the other produces CH4 by reacting hydrogen with CO2. This study is an experimental study to produce CH4 by reacting CO2 of biogas with hydrogen using a 40 wt% Ni-Mg-Al catalyst and a commercial catalyst. Catalyst characteristics were analyzed through H2-TPR, XRD, and XPS instruments of 40% Ni catalyst and commercial catalyst. The effect on the CO2 conversion rate and CH4 selectivity was analyzed, and the activities of a 40% Ni catalyst and a commercial catalyst were compared. As a result of experiment, In the case of a 40 wt% catalyst, the maximum CO2 conversion rate showed 77% at the reaction temperature of 400℃. Meanwhile, the commercial catalyst showed a maximum CO2 conversion rate of 60% at 450℃. When 50% of CO was added to the CO2 methanation reaction, the CO2 conversion rate was increased by about 5%. This is considered to be due to the atmosphere in which the CO reaction can occur without the process of converting to CH4 after forming carbon and CO as intermediates in terms of the CO2 mechanism on the catalyst surface.