수소생산 공정에서의 CO2 배출처 및 유효포집기술 분석

우경택,김봉규,소영석,백문석,박승수,정혜진 한국가스학회 2023 한국가스학회지 Vol.27 No.3

Energy consumption is increased by rapid industrialization. As a result, climate change is accelerating due to the increase in CO2 concentration in the atmosphere. Therefore, a shift in the energy paradigm is required. Hydrogen is in the spotlight as a part of that. Currently 95% of hydrogen is fossil fuel-based reforming hydrogen which is accompanied by CO2 emissions. This is called gray hydrogen, if the CO2 is captured and emission of CO2 is reduced, it can be converted into blue hydrogen. There are 3 technologies to capture CO2: absorption, adsorption and membrane technology. In order to select CO2 capture technology, the analysis of the exhaust gas should be carried out. The concentration of CO2 in the flue gas from the hydrogen production process is higher than 20%if water is removed as well as the emission scale is classified as small and medium. So, the application of the membrane technology is more advantageous than the absorption. In addition, if LNG cold energy can be used for low temperature CO2 capture system, the CO2/N2 selectivity of the membrane is higher than room temperature CO2 capture and enabling an efficient CO2 capture process. In this study, we will analyze the flue gas from hydrogen production process and discuss suitable CO2 capture technology for it.

Highly CO₂ selective membranes by potassium cations as carriers for facilitated transport with Ag₂O particles and free ions in ionic liquid

Park, Young Sung,Kang, Yong Soo,Kang, Sang Wook Elsevier 2017 CHEMICAL ENGINEERING JOURNAL -LAUSANNE- Vol.320 No.-

<P><B>Abstract</B></P> <P>The highly selective composite membranes consisting of ionic liquid 1-butyl-3-methyl imidazolium tetrafluoroborate (BMIM<SUP>+</SUP>BF<SUB>4</SUB> <SUP>−</SUP>)/Ag<SUB>2</SUB>O/KF were prepared for CO<SUB>2</SUB> separation. When Ag<SUB>2</SUB>O and KF were incorporated into BMIM<SUP>+</SUP>BF<SUB>4</SUB> <SUP>−</SUP>, the ideal selectivities of CO<SUB>2</SUB>/N<SUB>2</SUB> and CO<SUB>2</SUB>/CH<SUB>4</SUB> reached 105 and 52, respectively, with a CO<SUB>2</SUB> gas permeance of 31 GPU. These enhanced separation performance were attributable to synergistic effect of (1) K<SUP>+</SUP> cations in KF as CO<SUB>2</SUB> carriers for facilitated transport and (2) the oxide layer of the well-dispersed Ag<SUB>2</SUB>O and free ions in ionic liquid for improvement in CO<SUB>2</SUB> solubility. The coordinative interactions in the BMIM<SUP>+</SUP>BF<SUB>4</SUB> <SUP>−</SUP>/Ag<SUB>2</SUB>O/KF membrane were characterized by TGA, XPS, and FT-Raman spectroscopy.</P> <P><B>Highlights</B></P> <P> <UL> <LI> CO<SUB>2</SUB> separation membranes consisting of ionic liquid BMIMBF<SUB>4</SUB>/Ag<SUB>2</SUB>O/KF composite. </LI> <LI> Potassium cations as CO<SUB>2</SUB> carriers for facilitated transport. </LI> <LI> Enhanced solubility of CO<SUB>2</SUB> molecules by both Ag<SUB>2</SUB>O particles and free ions in ionic liquid. </LI> </UL> </P>

Effective CO₂ and CO Separation Using [M₂(DOBDC)] (M = Mg, Co, Ni) with Unsaturated Metal Sites and Excavation of Their Adsorption Sites

Kim, Hyunuk,Sohail, Muhammad,Yim, Kanghoon,Park, Young Cheol,Chun, Dong Hyuk,Kim, Hak Joo,Han, Seong Ok,Moon, Jong-Ho American Chemical Society 2019 ACS APPLIED MATERIALS & INTERFACES Vol.11 No.7

<P>Isostructural [M<SUB>2</SUB>(DOBDC)(EG)<SUB>2</SUB>] (M = Mg, Co, Ni) frameworks are first synthesized by controlling the pH* in the reaction medium. Coordinated ethylene glycols form a hexagonal OH cluster, which works as a template to grow single crystals with high crystallinity. After the liberation of solvated molecules, [M<SUB>2</SUB>(DOBDC)] shows notably higher surface areas than the reported values and completely different CO<SUB>2</SUB> and CO separation properties depending on the kinds of unsaturated metal. Therefore, breakthrough experiments using a CO<SUB>2</SUB>/CO mixed gas show that Mg-MOF has a longer breakthrough time for CO<SUB>2</SUB> than for CO, whereas Co/Ni-MOFs have longer breakthrough times for CO than for CO<SUB>2</SUB>. Apart from CO<SUB>2</SUB> and CO, other gases such as CH<SUB>4</SUB>, H<SUB>2</SUB>, and N<SUB>2</SUB> were almost not adsorbed at all in these materials at 298 K. To reveal the role of unsaturated metal sites, CO<SUB>2</SUB> and CO adsorption sites are unequivocally determined by single-crystal X-ray diffraction analysis. One of very interesting discoveries is that there are two CO<SUB>2</SUB> and CO adsorption positions (sites <B>A</B> and <B>B</B>) in the hexagonal channels. Site <B>A</B> is the unsaturated metal center working as Lewis acidic sites, and site <B>B</B> is the secondary adsorption site located between two <B>A</B> sites. A close inspection of crystal structures reveals that unsaturated Co(II) and Ni(II) sites adsorb both CO<SUB>2</SUB> and CO, whereas the unsaturated Mg(II) sites strongly capture only CO<SUB>2</SUB>, not CO. Density functional theory calculations elucidate the discrepancy in CO affinity: Co(II) and Ni(II) form strong π-back-donating bonds with CO via electron transfer from the d orbitals of the transition metals to the antibonding molecular orbitals of CO, whereas Mg(II) does not participate in electron transfer or orbital overlap with CO. This observation provides new insight into the synthesis of novel functional materials with high CO<SUB>2</SUB>/CO separation performance.</P> [FIG OMISSION]</BR>

2P-642 Modulation of bench-scale graphene oxide/polymer thin-film composite membrane for CO₂ separation and its CO₂ separation properties

유명진,유승연,이준혁,오지연,박호범 한국공업화학회 2017 한국공업화학회 연구논문 초록집 Vol.2017 No.1

Membrane technology for CO₂ separation has been intensively developed to reduce capture cost compared with amine-sorption technology in post combustion CO₂ capture of conventional power plants. However, the previous researches have been focused on the material development and lab-scale level experiments, so that the large scale production and operation of thin-film composite membranes under real gas condition have hardly been verified worldwide. In this study, we will propose several approaches to prepare large-scale (22cm x 34cm) CO₂ separation membranes using graphene oxide(GO) and highly CO₂-selectively permeable polymer composite material as well as their gas transport properties. In addition, the membranes were fabricated into the bench-scale plate-and-frame membrane module, which has membrane area about 15,000 ㎠, and the CO₂ separation properties of the membrane module will be discussed in this study.

CH4/CO2 separation from biogas stream using porous hydrophobic ceramic hollow fiber membrane contactors

이홍주,김민광,이승환,박정훈 한국화학공학회 2020 Korean Journal of Chemical Engineering Vol.37 No.6

Experiments were performed to separate CO2 from biogas using a ceramic hollow fiber membrane contactor (HFMC). CH4/CO2 mixed gas (34.5% CO2, CH4 balance) and monoethanolamine (MEA) were used. The influence of operating conditions, such as the gas flow rate, liquid flow rate, L/G ratio, CO2 partial pressure, and module type, on the CO2 removal efficiency and CO2 absorption flux was evaluated. As the gas flow rate increased, the CO2 removal efficiency decreased, while the CO2 absorption flux increased. The maximum CO2 removal efficiency was 96% at a gas flow rate of 0.1Nm3 h1 while the maximum CO2 absorption flux was 7.5×103 mol·m2·s1 at a gas flow rate of 1Nm3 h1. Moreover, the CO2 absorption flux and CO2 removal efficiency could be increased by more than 20% using the high-flux module.

지환족 다이안하이드라이드를 이용한 용해성 폴리이미드 공중합체 합성 및 메탄/이산화탄소 분리특성

박채영,이용택,김정훈 한국막학회 2014 멤브레인 Vol.24 No.1

지환족 다이안하이드라이드인 5-(2,5-dioxotetrahydrofuryl)-3-methyl-3-cyclohexene-1,2-dicarboxylic anhydride (DOCDA)와 4,4'-diaminodiphenyl ether (ODA)에서 합성된 폴리이미드는 유기용매에 잘 용해되는 폴리이미드로 알려져 있다.이러한 DOCDA-ODA 폴리이미드의 기체 투과특성을 평가하고 투과선택도를 개선시키기 위해서 DOCDA-ODA 반응물에 세가지 dianhydride 단량체((4,4'-(hexafluoroisoproplidene)diphthalic anhydride (6FDA), 4,4'-biphthalic anhydride (BPDA), 3,3’,4,4’-benzophenone tetracarboxylic dianhydride (BTDA))를 각각 20 mol% 첨가하여 순수중합체 및 공중합체를 합성하였다. 폴리이미드 합성이 성공적으로 이루어졌음을 FT-IR을 통해 확인하였고, 그들의 열적특성은 DSC를 통해 알아보았다. 제조된폴리이미드들의 CO2/CH4에 대한 기체투과도와 선택도는 time-lag법을 이용하여 측정하였다. 그 결과 순수고분자인 DOCDA-ODA의 경우 CO2 투과도는 1.71 barrer, CO2/CH4 선택도는 74.35의 우수한 투과특성을 보였다. 세 가지 공중합체의 경우 DOCDA-ODA에 비해 CO2 투과도는 높게 나타난 반면에 CO2/CH4 선택도는 감소하였다. 특히, 6FDA를 첨가한 경우 CO2/ CH4 선택도는 DOCDA-ODA보다 다소 낮은 결과를 나타내었지만 CO2 투과도가 크게 증가하였음을 확인할 수 있었다. In this study, four soluble homo- and co-polyimides using 5-(2,5-dioxotetrahydrofuryl)-3-methyl-3-cyclo-hexene-1,2-dicarboxylic anhydride (DOCDA) and 4,4'-diaminodiphenyl ether (ODA) monomers were synthesized to develop the gas separation membrane with good CO2/CH4 separation properties. To prepare the copolyimides, 20 mol% of three dia-nhydrides - (4,4'-(hexafluoroisoproplidene)diphthalic anhydride (6FDA), 4,4'-biphthalic anhydride (BPDA), 3,3’,4,4’-benzo-phenone tetracarboxylic dianhydride (BTDA) - were added in DOCDA-ODA monomer mixture, respectively. All the synthe-sized homo- and co-polyimides were characterized by FT-IR. Their thermal properties were analyzed with differential scan-ning calorimeter (DSC). Dense membranes were prepared from these copolyimides to check their gas permeation properties for CO2 and CH4 gases using a time-lag method. The permeation testing results are as follows; DOCDA/ODA homopolymer showed 1.71 barrer of CO2 permeability and 74.35 of CO2/CH4 selectivity. The three polyimide copolymers (DOCDA/ 6FDA-ODA, DOCDA/BPDA-ODA, DOCDA/BTDA-ODA) showed lower CO2/CH4 selectivities and higher CO2 per-meabilities than the homopolymer (DOCDA-ODA). DOCDA/6FDA-ODA showed twice times higher CO2 permeabilities without severe CO2/CH4 selectivity loss than the DOCDA-ODA.

DME 플랜트 CO2흡수탑 대체용 고분자 분리막 모듈

정종태,이충섭,고형철,하성용,남상용,조원준,백영순 한국막학회 2012 멤브레인 Vol.22 No.2

DME 제조공정에서 발생하는 혼합가스 중 CO2를 제거하기 위해서 H2 투과도보다 CO2투과도가 우수한 고무상 고분자를 분리소재로 선정하여 복합막을 제조하고 CO2/H2의 분리성능을 검증하여 보았다. 지지체 중공사막 소재로 PEI를 이용하여 지지체 중공사막을 제조하였으며, 제조된 지지체 중공사막의 기체투과도를 각 가스별로 측정하여 PDMS의 경우는 CO2 투과도 300 GPU 이상, CO2/H2의 선택도가 4.3 이상, PEBAX를 사용한 경우 CO2 투과도 120 GPU 이상 CO2/H2의 선택도가 5 이상인 복합 중공사를 제조하였다. In order to remove CO2 from the DME plant process, we investigated the composite membrane with rubbery polymers as the separation layer and its separation performance of CO2 and H2. Hollow fiber membranes for supporting layer were prepared by solution spinning method. In case of using PDMS as a separation layer, the composite membranes showed the permeation rates of CO2 were over 300 GPU and minimum CO2/H2 selectivitties were 4.3 and in case of using PEBAX as a separation layer, the composite membranes showed the permeation rates of CO2 were over 120 GPU and minimum CO2/H2 selectivities were 5.

CO2-염수 상대 투과도 측정에서 고압 2상 분리기를 이용한 포화도 측정

정구선,허대기,이재형 한국자원공학회 2012 한국자원공학회지 Vol.49 No.2

CO2 geological storage has been recognized as one of the most effective CO2 mitigation method due to its significant amount of storage capacity and high efficiency in the field application. CO2-brine relative permeability data is necessary to understand the fluid flow, displacement characteristics and storage mechanism of injected CO2 into deep saline aquifer. Most of the previous studies did not consider CO2 solubility and only few CO2-brine relative permeability data shows quantitative saturation measurement at aquifer condition. In this study we developed a high pressure 2-phase separator to quantitatively measure fluid saturation of CO2-brine relative permeability and introduced a closed circulation system to consider CO2 solubility. The relative permeability results measured using high pressure 2-phase separator are similar to the experimental results measured using CT sacn. CO2 지중저장은 막대한 양의 CO2 처분이 가능하고 현장 적용성이 높아 국제사회에서 효과적인 CO2 감축 방안 중 하나로 인정받고 있다. CO2 지중저장 시 대수층으로 주입된 CO2의 유동 및 축출 특성, 저장 메커니즘을 이해하기 위해서는 염수와 CO2의 상대 투과도 자료가 필요하다. 기존의 염수와 CO2의 상대 투과도 측정연구에서는 염수에 용해되는 CO2의 양을 고려하지 않았고 대기압 조건에서 포화도를 결정하였기 때문에 불확실성을 내포하고 있다. 이러한 문제를 해결하기 위해 본 연구에서는 밀폐 순환형의 시스템을 도입하여 염수에 용해되는 CO2의 양을 일정하게 유지시켰으며 고압 2상 분리기를 설계, 제작하여 실험 조건에서 암석 시료 내 포화되어 있는 유체의 양을 정량적으로 측정하였다. 고압 2상 분리기를 사용하여 측정된 염수와 CO2의 상대투과도 실험 결과는 CT scan을 사용하여 측정된 실험 결과와 상당히 유사한 양상을 보였다.

고투과성 세라믹 중공사 개발과 접촉막 공정의 CH4/CO2 분리 특성 평가

이승환,김민광,정병준,장학룡,박정훈 한국막학회 2020 멤브레인 Vol.30 No.4

In this study, CO2 separation experiment was performed on a CH4/CO2 mixed gas using a ceramic hollow fiber membrane contactor (HFMC). In order to fabricate high-performance HFMC, experiments were conducted to manufacture high-permeability hollow fiber membranes, and the prepared hollow fiber membranes were evaluated through N2 gas permeation experiments. HFMC for CH4/CO2 mixed gas separation was manufactured using the manufactured high-permeability hollow fiber membrane. In the experiment, mixed gas of CH4/CO2 (34.5% CO2, CH4 balance) and monoetanolamine (MEA) was used, and the effect of CO2 removal efficiency on the flow rate of the absorbent was evaluated. The CO2 removal efficiency increased as the liquid flow rate increased, and the CO2 absorption flux also increased with the liquid flow rate. 본 연구에서는 세라믹 중공사 접촉막 모듈을 이용하여 CH4/CO2 혼합가스에서 CO2 분리 실험을 수행하였다. 높은성능의 접촉막 모듈을 제작하기 위해 고투과성 중공사막의 제조 실험을 진행하였으며, 제조한 중공사막은 N2 기체투과실험을통해 투과 성능을 평가하였다. 최종적으로 고투과도 중공사막을 이용하여 CH4/CO2 혼합 기체 분리를 위한 Hollow fiber membrane contactor (HFMC)를 제작하였다. 실험에는 CH4/CO2 혼합 기체(34.5% CO2, CH4 balance)와 monoethanolamine (MEA) 를 사용하였으며, CO2 제거 효율이 흡수제의 유량에 따라 어떠한 영향을 받는지 평가하였다. CO2 제거 효율은 액체유량이증가함에 따라 같이 상승하였으며, CO2 흡수 flux 또한 액체유량과 함께 증가하는 결과를 보였다.

Na형 Faujasite 제올라이트 분리막 형성 및 CO2/N2 분리

Churl Hee Cho,Jeong Gu Yeo,Young Soo Ahn,Moon Hee Han,Yong Ha Kim,Sang Hoon Hyun 한국막학회 2007 멤브레인 Vol.17 No.3

다양한 재료특성(Si/Al 몰비, 두께, 구조적 불완전성)을 갖는 Na형 faujasite 제올라이트 분리층을 다공성 α-알루미나 튜브 표면에 수열조건에서 이차성장 시키고 CO2/N2 분리거동을 CO2/N2 몰비가 1인 혼합기체에 대하여 30℃에서 평가하였다. 수열조건 중에서 수열용액 내의 SiO2 양은 형성된 제올라이트 분리층의 재료특성에 가장 큰 영향을 주는 변수임을 확인하였다. 즉, 수열용액 내의 SiO2 양이 증가함에 따라서 형성된 제올라이트 분리층의 Si/Al 몰비, 두께, 구조적 불완전성(discontinuity)은 동시에 증가하였다. 본 논문에서는 불완전한 치밀화에 의해 잔존하는 결정립간 공극(void), GIS Na-P1 상에 의해 형성된 균열(crack) 등 구조적 불완전성이 CO2/N2 분리에 가장 큰 영향을 주는 재료특성이며, 투과부에서의 CO2 탈착이 전체 CO2 투과의 율속단계(rate-determining step)임을 확인하였다. Sodium type faujasite(FAU) zeolite layers with diverse materials characteristics(Si/Al ratio, thickness, and structural discontinuity) were hydrothermally grown on a porous α-Al2O3 tube, and then the CO2/N2 separation was evaluated at 30℃ for an equimolar mixture of CO2 and N2. Among hydrothermal conditions, SiO2 content in hydrothermal solution seriously affected materials characteristics: with an increment in the SiO2 content, Si/Al ratio, thickness, and structural discontinuity of grown FAU zeolite layer simultaneously increased. The present study reveals that structural discontinuity(intercrystalline voids due to an incomplete densification and cracks induced by GIS Na-P1 phase) is the most important variable affecting the CO2/N2 separation. Also, it was suggested that the CO2 desorption in permeate side be the rate-determining(slowest) step in the overall CO2 permeation.