• 한국대기환경학회지
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• 제26권6호
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• pp.683-689
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• 2010

Reforming of methane with carbon dioxide has been carried out using a bipolar pulse driven elongated arc reactor operating at atmospheric pressure and non-equilibrium regime. This plasma reactor is driven by two kinds of power supply, characterized by different voltage-current characteristics under the same operating power and frequency. Varying the $CO_2/CH_4$ ratio and the discharge power, the conversion rate, yield, and reforming efficiency for the two power supplies are investigated in conjunction with the static and dynamic behaviors of voltage and current. It is found that not only the values of voltage and current but also their shapes give an influence on the reforming performances. Finally, a better electrical operation regime for the efficient plasma reforming is proposed based on the relationship between the voltage-current characteristics and the reforming performance.

• 에너지공학
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• 제19권4호
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• pp.240-245
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• 2010

화석연료는 사용 후 재생이 불가능하고 매장량이 한정되어 있으며, 연소 시 발생되는 각종 공해물질로 인해 환경문제를 야기하고 있다. 이러한 맥락에서 차세대 청정대체에너지로서 주목을 받고 있는 것이 바로 수소에너지이다. 현재 가장 경제성이 있는 수소제조방법으로 알려진 천연가스 Steam Reformig(SRM)은 천연가스의 매장량 한계성으로 인해 그 제조비용이 높아지고 있어, 바이오매스 및 유기성 폐기물의 가스화를 통한 수소생산방법이 자원의 재순환, 페기물 처리, 열원의 이용, 직접적인 $CO_2$ 삭감 등의 부수적인 효과가 높아 경제성 있는 수소제조법으로 많은 연구가 진행되고 있다. 이에 본 연구에서는 잠재적으로 고갈 염려가 있는 화석연료를 대체하고, 화석연료의 연소 시 발생되는 환경문제를 해결하고자 열분해로와 고온개질기로 구성된 Pilot-scale Two Stage Gasifier를 개발하고, 본 장치 내에서의 biomass의 가스화 특성을 평가하고자 한다. 열분 해로에서의 가스화 실험 결과, 열분해로의 전환율은 약 70%로 나타났으며, $H_2$, $CH_4$, CO, $CO_2$의 평균 생성량은 각각 16.7, 11.3, 37.2, 26.6 L/mim의 결과를 보였다. 고온개질기로부터의 생성가스 수율의 결과로부터, 고온개질기에 적용된 $1100^{\circ}C$의 초고온에서의 개질 반응에 의해 $CH_4$의 대부분이 환원됨을 확인할 수 있었다. 본 연구로부터 개발된 장치의 냉가스 효율은 53.2%로 비교적 높은 결과가 얻어졌으며, 수소에 대한 평균 생성량은 55.4 L/min의 결과를 보였다.

• 한국태양에너지학회:학술대회논문집
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• 한국태양에너지학회 2011년도 춘계학술발표대회 논문집
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• pp.275-281
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• 2011

Solar reforming of methane with $CO_2$ was successfully tested with a direct irradiated absorber on a parabolic dish capable of $5kW_{th}$ solar power. The new type of catalytically activated metallic foam absorber was prepared, and its activity was tested. Ni was applied as the active metal on the gamma - alumina coated Ni metal foam for the preparation of the catalytically-activated metal foam layer. Compared to conventional direct irradiation of the catalytically-activated ceramic foam absorber, this new metallic foam absorber is found to exhibit a superior reaction performance at the relatively low insolation or at low temperatures. In addition, unlike direct irradiation of the catalytically-activated ceramic foam absorber, metallic foam absorber has better thermal resistance, which prevents the emergence of cracks caused by mechanical or thermal shock. The total solar power absorbed reached up to 2.1kW and the maximum $CH_4$ conversion was almost 40%.

• 신재생에너지
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• 제20권1호
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• pp.126-134
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• 2024

Biogas, composed mainly of methane (CH₄) and carbon dioxide (CO₂), is a renewable gas that can serve as an alternative energy source. In this study, we developed a new microwave reformer and analyzed its reforming characteristics. We observed that higher temperatures of the microwave receptor led to increased reforming efficiency. By supplying appropriate amounts of methane and steam, we could prevent carbon generated from the thermal decomposition reaction of carbon dioxide from depositing on the catalytic active layer, thus avoiding the inhibition of catalytic activity. Hydrogen generation was enhanced when maintaining the biogas ratio and steam supply at adequate levels. Increasing the SiC ratio in the receptor improved the uniformity of temperature distribution and growth rate, resulting in higher conversion rates of the reforming process.

• Carbon letters
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• 제9권4호
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• pp.289-293
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• 2008

Naphtha Cracking Bottom (NCB) oil was heat reformed at various reforming temperature and time, and the volatile extracts were characterized including yields, molecular weight distributions, and representative compounds. The yield of extract increased as the increase of reforming temperature ($360{\sim}420^{\circ}C)$ and time (1~4 hr). Molecular weight of the as-received NCB oil was under 200, and those of extracts were distributed in the range of 100-250, and far smaller than those of precursor pitches of 380-550. Naphtalene-based compounds were more than 70% in the as-received NCB oil, and most of them were isomers of compounds bonding functional groups, such as methyl ($CH_{3^-}$) and ethyl ($C_2H_{5^-}$). When the as-received NCB oil was reformed at $360^{\circ}C$ for 1 hr, the most prominent compound was 1,2-Butadien, 3-phenyl- (24.57%), while naphthalene became main component again as increasing the reforming temperature.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2010년도 춘계학술대회 초록집
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• pp.226.1-226.1
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• 2010

본연구에서는 GTL(gas to liquids)공정의 합성가스 생산을 위해 수증기-이산화탄소 복합개질반응(Combined Steam and Carbon dioxide Reforming of Methane, CSCRM)을 수행하였다. CSCRM은 수증기와 이산화탄소의 공급비 조절을 통해 $H_2$/CO비를 2로 맞추기 용이한 장점을 지니고 있어 다른 단일 개질 반응과 달리 합성가스 생산 시 $H_2$/CO 비율을 조절하기 위한 부가적인 공정이 필요하지 않아 경제적인 공정이다. 일반적으로 사용되는 Ni개질촉매는 가격대비 우수한 성능을 보이지만 S/C비가 낮은 CSCRM의 경우 촉매표면의 탄소침적에 의한 비활성화가 야기되는 문제점이 있다. 따라서 본 연구에서는 산소저장능력과 산소전달능력이 우수한 $CeO_2$를 조촉매로 첨가하여 표면에 형성된 코크 제거가 용이하도록 하였다. Ni-Ce/$MgAl_2O_4$촉매는 동시함침법(co-impregnation)으로 제조하였으며, Ni의 함량을 10wt%로 고정한 상태에서 Ce의 함량을 조절하여 Ce/Ni 최적비를 찾고자 하였다. XRD, TPR, BET, $H_2$-Chemisorption과 같은 촉매의 특성분석을 통해 촉매의 비표면적, 환원특성과 Ni입자의 분산도 등을 확인하였다. Ce를 첨가함에 따라 Ce2.5wt%까지는 비표면적이 증가하다가 이후 점차 줄어드는 경향성을 보였다. 또한, $H_2$-Chemisorption 결과 역시 비표면적과 유사한 경향성을 보였는데, Ce5.0wt%까지 Ni 분산도가 증가 하다가 다시 감소하는 것을 확인할 수 있었다. 반응실험은 $H_2O:CO_2:CH_4:N_2$ = 0.8:0.4:1:1의 공급조건에서 수행하였으며, 질소와 수소 환원분위기로 $700^{\circ}C$에서 1시간 환원 후 $650^{\circ}C$에서 $550^{\circ}C$범위로 온도를 떨어뜨려가면서 반응을 수행하였다. Ce를 첨가함에 따라 $CH_4$ 전환율이 증가를 하다가 Ce2.5wt% 이후 감소하는 것을 확인할 수 있었다. 이러한 높은 촉매 활성은 Ce 첨가로 인해 환원특성이 좋아지고 Ni분산도가 증가하여 담체와 강한 상호작용(SMSI)을 형성함으로 탄소침적 저항성 강화에 기인한 것이다.

• 청정기술
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• 제20권2호
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• pp.189-201
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• 2014

합성가스를 생산하기 위한 부분산화, 이산화탄소 리포밍, 메탄에 의한 산화$CO_2$ 리포밍 공정들은 니켈 하이드로탈사이트($Ni_{0.5}Ca_{2.5}Al$) 촉매를 이용하여 수행되었고 안정한 이중층 구조를 형성시키기 위한 금속지지체(Mg, Ca)의 영향에 대해서도 다양한 연구가 진행되었다. 지지체전구물질(Mg, Ca)에 따라 메탄 리포밍의 안정성은 활성니켈이온과 지지체금속이온 사이의 결합강도차이에 의해 영향을 받는다. Ni-Mg-Al 구성체는 가장 안정한 하이드로탈사이트 이중층 구조이지만 Ni-Ca-Al 구성체는 그렇지 않다. 이산화탄소 리포밍 장기테스트에서 Ni-Mg-Al 촉매는 약 100시간 동안 80%의 효율을 유지하면서 탁월한 안정성을 보였지만 Ni-Ca-Al 촉매는 반응초기에 불활성화됨을 확인할 수 있었다. 활성금속 Ni과 지지체 Mg-Al 사이의 결합강도를 확인하기 위해 승온 환원(temperature-programmed reduction, TPR) 분석을 시행하였다. 이를 통해 Ni-Mg-Al 촉매가 Ni-Ca-Al 촉매보다 Ni의 환원온도가 더 높음을 확인할 수 있었다. $Ni_{0.5}Ca_{2.5}Al$ 촉매는 가장 높은 초기반응성을 보였지만 코크형성으로 인해 반응성이 빠르게 감소하였다. 결론적으로 $Ni_{0.5}Ca_{2.5}Al$ 촉매가 코크형성에 대한 강한 저항성을 갖고 있기 때문에 다른 촉매들보다 높은 반응성과 안정성을 갖는 것으로 보여진다.

• Bulletin of the Korean Chemical Society
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• 제35권9호
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• pp.2615-2620
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• 2014

Ni/$La_2O_3$ with a high dispersion was prepared by reduction of $La_2O_3$ perovskite oxide to examine the catalytic activity for the $CO_2-CH_4$ reaction. The Ni/$La_2O_3$ catalyst was found to be highly active for the reaction. The ratios of $H_2$/CO were measured in a flow of the reaction mixture containing $CO_2/CH_4$/Ar using an on-line gas chromatography system operated at 1 atm and found to be varied with temperature between 0.66 and 1 in the temperature range of $500-800^{\circ}C$. A kinetic study of the catalytic reaction was performed in a static reactor at 40 Torr total pressure of $CO_2/CH_4/N_2$ by using a photoacoustic spectroscopy technique. The $CO_2$ photoacoustic signal varying with the concentration of $CO_2$ during the catalytic reaction was recorded as a function of time. Rates of $CO_2$ disappearance in the temperature range of $550-700^{\circ}C$ were obtained from the changes in the $CO_2$ photoacoustic signal at early reaction stage. The plot of ln rate vs. 1/T showed linear lines below and above $610^{\circ}C$. Apparent activation energies were determined to be 10.4 kcal/mol in the temperature range of $550-610^{\circ}C$ and 14.6 kcal/mol in the temperature range of $610-700^{\circ}C$. From the initial rates measured at $640^{\circ}C$ under various partial pressures of $CO_2$ and $CH_4$, the reaction orders were determined to be 0.43 with respect to $CO_2$ and 0.33 with respect to $CH_4$. The kinetic results were compared with those reported previously and used to infer a reaction mechanism for the Ni/$La_2O_3$-catalyzed $CO_2-CH_4$ reaction.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2008년도 춘계학술대회 논문집
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• pp.247-250
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• 2008

Biomass gasification is a promising technology for producing a fuel gas which is useful for power generation systems. In biomass gasification processes, tar formation often causes some problems such as pipeline plugging. Thus, proper tar treatment is necessary. So far, nickel (Ni)-based catalysts have been intensively studied for the catalytic tar removal. However, the deactivation of Ni-based catalysts takes place because of coke deposition and sintering of Ni metal particles. To overcome these problems, we have been using ruthenium (Ru)-based catalyst for tar removal. It is reported by Okada et al., that a Ru/$Al_2O_3$ catalyst is very effective for preventing the carbon deposition during the steam reforming of hydrocarbons. Also, this catalyst is more active than the Ni-based catalyst at a low steam to carbon ratio (S/C). Benzene was used for the tar model compound because it is the main constituent of biomass tar and also because it represents a stable aromatic structure apparent in tar formed in biomass gasification processes. The steam reforming process transforms hydrocarbons into gaseous mixtures constituted of carbon dioxide ($CO_2$), carbon monoxide (CO), methane ($CH_4$) and hydrogen ($H_2$).

• 대한기계학회논문집B
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• 제33권11호
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• pp.869-875
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• 2009

The purpose of this paper is to investigate the optimal condition of the syngas production by reforming of propane using Gliding arc plasma reformer. The gliding arc plasma reformer in 3 phases has been newly designed and developed with a quick starting and fast response time. It can be applicable to the various types of fuels (Hydrocarbons $C_xH_y$), and it has a high conversion rate of fuels and high production of hydrogen. The parametric screening studies were carried out according to the changes of a steam feed amount i.e., steam/carbon ratio, total gas flow rate and input electric power. The optimum operating conditions were S/C ratio 2.8, total gas flow rate of 14 L/min and input electric power of 2.4 kW. The result of optimum operating conditions showed the 55 % $H_2$, 14 % CO, 15 % $CO_2$, 10 % $C_3H_8$ and 4 % $CH_4$. Also, $C_3H_8$ conversion, $H_2$ yield and $H_2$ selectivity were 90 %, 42 %, 15 %, respectively. The energy efficiency and specific energy requirements were 37 % and 334 kJ/mol respectively.