• Title, Summary, Keyword: Methane ($CH_4$)

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Partial Oxidation of Methane in Palladium-silver Alloy Membrane Reactor (팔라듐-은 막반응기를 이용한 메탄의 부분산화반응)

  • Choi, Tae-Ho;Kim, Kwang-Je;Moon, Sang-Jin;Suh, Jung-Chul;Baek, Young-Soon
    • Applied Chemistry for Engineering
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    • v.16 no.5
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    • pp.641-647
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    • 2005
  • The partial oxidation of methane is one of important processes for hydrogen production. As a membrane reactor, palladium-silver (Pd-Ag) alloy membrane prepared by electroless plating technique was employed for partial oxidation of methane. The experimental variables were reaction temperature, $O_2/CH_4$ mole ratio, $CH_4$ feed rate, and $N_2$ sweep gas flow rate. The methane conversions increased with the reaction temperatures in the range of 350 to $730^{\circ}C$. The highest methane conversion and CO selectivity were obtained at the condition of $O_2/CH_4$ mole ratio of 0.5 and $730^{\circ}C$ using commercially available nickel/alumina catalyst. The Pd-Ag membrane reactor showed higher methane conversions, 10~40% higher, compared to those in a traditional reactor.

Assessment of methane emission with application of rice straw in a paddy field

  • Choi, Eun Jung;Jeong, Hyun Cheol;Kim, Gun Yeob;Lee, Sun Il;Gwon, Hyo Suk;Lee, Jong Sik;Oh, Taek Keun
    • Korean Journal of Agricultural Science
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    • v.46 no.4
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    • pp.857-868
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    • 2019
  • A flooded rice field is one of the significant sources of anthropogenic methane (CH4) with the intensity of the emissions dependent on management practices. Incorporation of rice straw, which is one of the organic amendments, induces the increase of methane emissions during the flooding season. In this study, we measured of methane emission according to applications of rice straw in different soil textures during a cultivation period in 2017 and 2018. The fallow treatments were non application of rice straw (NA), spring plowing after spring spreading of rice straw (SPSA), spring plowing after previous autumn spreading of rice straw (SPAA), and autumn plowing after previous autumn spreading of rice straw (APAA). The SPSA treatment emitted the highest total methane from loam soil in both 2017 (596.7 CH4 kg ha-1) and 2018 (795.4 CH4 kg ha-1). The same trend was observed in silt clay loam soil; the SPSA treatment still emitted the highest amount of methane in both 2017 (845.9 CH4 kg ha-1) and 2018 (1,071.7 CH4 kg ha-1). The lowest emission among the rice straw incorporated plots came from the APAA treatment for both soil texture types in all the seasons. The conversion factors of the SPAA were 0.79 and 0.65 from the loam and silt clay loam soils, respectively. Relatedly, the conversion factors of the APAA were 0.71 and 0.43 from the loam and silt clay loam soils, respectively. The above observations mean therefore that incorporation of rice straw early in the fallow reduces methane emissions in the main rice growing season.

Partial Oxidation of Methane over Ni/SiO2

  • Roh, Hyun-Seog;Dong, Wen-Sheng;Jun, Ki-Won;Liu, Zhong-Wen;Park, Sang-Eon;Oh, Young-Sam
    • Bulletin of the Korean Chemical Society
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    • v.23 no.5
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    • pp.669-673
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    • 2002
  • Ni catalyst (Ni: 15 wt%) supported on precalcined SiO2 has been investigated in reforming reactions of methane to synthesis gas. The catalyst exhibited fairly good activity and stability in partial oxidation of methane (POM), whereas it deactivated in steam reforming of methane (SRM). Pulse reaction results of CH4, O2, and CH4/O2 revealed that Ni/SiO2 has high capability to dissociate methane. The results also revealed that both CH4 and O2 are activated on the surface of metallic Ni, and then surface carbon species react with adsorbed oxygen to produce CO and CO2 depending on the bond strength of the oxygen species on the catalyst surface.

Preponderant Occurrence of sl natural methane hydrates: Spectroscopic analysis of crystalline structure transition (sI 천연 메탄하이드레이드의 존재 : 결정구조 변화의 분광학적 분석)

  • Yeon, Sun-Hwa;Seol, Ji-Woong;Lee, Huen
    • 한국신재생에너지학회:학술대회논문집
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    • pp.387-390
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    • 2006
  • We report here that under strong attacksof external $CH_4$ guest molecules the sII and sH methane hydrates are structurally transformed to the crystalline me framework of sI, leading to favorable change of the lattice dimension of the host-guest networks. The High Power Decoupling $^{13}C$ NMR and Raman spectroscopies were used to identify structure transitions of the mixed $CH_4+C_2H_6$ hydrates (sIIl) and hydrocarbons (methylcyclohexane, isopentane) + $CH_4$ hydrates (sH). The resulting spectra indicate that most of the synthesized sII and sH hydrates were transformed to methane hydrate of sl under 110 bar and particularly the coexistence of sl with sII or sH appear according to the surrounding methane-rich gas conditions. The present findings might be expected to Provide rational evidences regarding the preponderant occurrence of naturally-occurring sI methane hydrates in marine sediments.

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Establishment of Baseline Emission Factor of Methane in Korean Rice Paddy Soil (국내 벼 논에서 메탄 기본배출계수 개발)

  • Kim, Gun-Yeob;Jeong, Hyun-Cheol;Ju, Ok-Jung;Kim, Hee-Kwon;Park, Jun-Hong;Gwon, Hyo-Suk;Kim, Pil-Joo
    • Korean Journal of Environmental Agriculture
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    • v.32 no.4
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    • pp.359-365
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    • 2013
  • BACKGROUND: Methane ($CH_4$) emission is calculated using the default $CH_4$ emission factor as recommended by the International Panel on Climate Change(IPCC guidelines). However, the default emission factor has been derived using including the data from other countries having different soil and environmental conditions and may not reflect the real $CH_4$ emission rates in Korea. The objective of this study was to estimate the baseline emission factor of $CH_4$ in Korean paddy soils during rice cultivation. METHODS AND RESULTS: Methane emission patterns were characterized in four different paddy soils across country for a consecutive 3 years during the rice cultivation period. Rice plants were cultivated under continuous flooding and fertilized using the recommended chemical fertilization in Korea ($N-P_2O_5-K_2O$=90-45-57kg/ha). The mean $CH_4$ emission rate was 2.32 kg $CH_4$/ha/day and the uncertainty of the investigated data was 21.7%, with a valuable error range at 1.82-2.82 kg $CH_4$/ha/day with a 95% confidence interval. CONCLUSION(S): Conclusively, the Korean paddy soils' baseline emission factor of $CH_4$ is approximately 2.32 kg $CH_4$/ha/day and can be used to estimate the $CH_4$ emissions more exactly.

Influence of Different Rice Varieties on Emission of Methane in Soil and Exudation of Carbohydrates in Rhizosphere (벼 품종별 Methane 배출과 뿌리의 탄수화물 분비 특성)

  • Lee, Kyeong-Bo;Lee, Deog-Bae;Uhm, Taik-Yong;Kim, Jong-Gu;Yoo, Chul-Hyun;Kim, Yong-Woong
    • Korean Journal of Soil Science and Fertilizer
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    • v.30 no.3
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    • pp.257-264
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    • 1997
  • To find out the influence of different rice varieties on the emission of methane in the soil and the exudation of carbohydrates from root, the experiment was conducted on a fine silty, mesic family of Aeric Fluventinc Haplaquepts (Jeonbug series). The varities of rise involved one early maturing variety of Japonica type(namweon) and three mid-to-late maturing varieties of Japonica type and one mid-to-late variety of Indica${\times}$Japonica crossed. The methane flux over the rice canopy was measured according to the closed chamber method modified by Shin and the methane concentration in the soil was measured using porous cup installed in the soil. The carbohydrate exudates from root were measured under nutrient solution culture. It was found that the methane flux tended to be lower in early maturing varieties than in the mid-to-late maturing varieties, lower in indica${\times}$Japonica crossed variety than in Japonica type varieties. There was positive correlation between the number of tillers and the weight of roots of rice plant and methane flux. The correlation, however, tended to be greater between the weight of roots and methane flux. There was no significant difference in the concentration of methane in the soil under different varieties of rice, excepting one variety, Kehwa under which methane concentration was highest. In case of carbohydrate exudation, early maturing variety tended to be higher than other varieties, although the opposite was the case in methane flux.

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Autothermal Reforming of Methane using Metallic Monolith Catalyst Coated Ni/CeO2-ZrO2 (금속모노리스에 부착된 Ni/CeO2-ZrO2를 이용한 메탄의 자열개질반응)

  • Lee, Tae Jun;Cho, Kyung Tae;Lee, Jong Dae
    • Korean Chemical Engineering Research
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    • v.45 no.6
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    • pp.663-668
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    • 2007
  • The autothermal reforming reaction of methane was investigated to produce hydrogen with $Ni/CeO_2-ZrO_2$ catalysts. Alumina-coated honeycomb monolith was applied in order to obtain high catalytic activity and stability in autothermal reforming of methane. Metallic monolithic catalyst showed better methane conversion than that of powder type at high reaction temperature. It was confirmed that $H_2O/CH_4/O_2$ ratio was important factor in autothermal reforming reaction. $H_2$ yield was increased as $H_2O/CH_4$ ratio increased. Methane conversion was improved as $O_2/CH_4$ ratio was increased, whereas, the yield of $H_2$ was decreased. The catalytic activity for $Ni/CeO_2-ZrO_2$ catalyst with 0.5 wt% Ru loading was improved at low reaction temperature.

Biochemical Methane Potential and Biodegradability of Animal Manure and Cultivated Forage Crops at the Reclaimed Tideland (가축분뇨와 간척지 사료작물의 메탄발생량과 생분해도)

  • Heo, Nam-Hyo;Lee, Seung-Heon;Kim, Byeong-Ki
    • New & Renewable Energy
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    • v.4 no.4
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    • pp.56-64
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    • 2008
  • Anaerobic biodegradability (AB), which can be determined with the ultimate methane yield by the decomposition of organic materials, is one of the important parameters for the design and the operation of anaerobic digestion plant. In this study, Biochemical methane potential (BMP) test has been carried out to evaluate the methane yields of animal manures such as pig and cattle slurries, and different forage crops cultivated at the reclaimed tideland such as maize, sorghum, barley, rye, Italian ryegrass (IRG), rape, rush, and waste sludge produced from slaughterhouse wastewater treatment plant (SSWTP). In the ultimate methane yield and biodegradability of animal manure, those of pig slurry were 345 $mlCH_4/gVS_{fed}$ and 44.7% higher than 247 $mlCH_4/gVS_{fed}$ and 46.4% of cattle slurry (Cat. 2). The ultimate methane yield and biodegradability of spike-crop rye (Rye 1) were 442.36 $mlCH_4/gVS_{fed}$ and 86.5% the highest among different forage crops, those of the other forage crops ranged from 306.6 to 379 $mlCH_4/gVS_{fed}$ of methane yield with the AB having the range of about 60 to 77%. Therefore the forage crops could be used as a good substrate to increase the methane production and to improve the biodegradability in anaerobic co-digestion together with animal manure.

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Low Temperature Methane Steam Reforming for Hydrogen Production for Fuel Cells

  • Roh, Hyun-Seog;Jun, Ki-Won
    • Bulletin of the Korean Chemical Society
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    • v.30 no.1
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    • pp.153-156
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    • 2009
  • Low temperature methane steam reforming to produce $H_2$ for fuel cells has been calculated thermodynamically considering both heat loss of the reformer and unreacted $H_2$ in fuel cell stack. According to the thermodynamic equilibrium analysis, it is possible to operate methane steam reforming at low temperatures. A scheme for the low temperature methane steam reforming to produce $H_2$ for fuel cells by burning both unconverted $CH_4$ and $H_2$ to supply the heat for steam methane reforming has been proposed. The calculated value of the heat balance temperature is strongly dependent upon the amount of unreacted $H_2$ and heat loss of the reformer. If unreacted $H_2$ increases, less methane is required because unreacted $H_2$ can be burned to supply the heat. As a consequence, it is suitable to increase the reaction temperature for getting higher $CH_4$ conversion and more $H_2$ for fuel cell stack. If heat loss increases from the reformer, it is necessary to supply more heat for the endothermic methane steam reforming reaction from burning unconverted $CH_4$, resulting in decreasing the reforming temperature. Experimentally, it has been confirmed that low temperature methane steam reforming is possible with stable activity.

Analysis of Methane from Screened Soil of Closed Landfill and Application of Landfarming for the Reduction of the Methane (사용종료 매립지 선별토양의 메탄 발생 분석 및 토양경작기술 적용 효과 연구)

  • Kim, Kyung;Yang, Jae-Kyu;Chang, Yoon-Young
    • Journal of Soil and Groundwater Environment
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    • v.15 no.5
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    • pp.40-45
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    • 2010
  • In this study, methane production by reuse of screened soil of landfill was estimated and the effect of application of landfarming for the reduction of methane was investigated. The study soil sampled from S closed landfill contains VS 9.8~12.8% and its BOD/COD is 0.31~0.33 which is more than three times over 0.1, the BOD/COD stabilization criteria of Ministry of Environment. The effective remediation technology for the reduction of organics of soil, landfarming was applied to the screened soil for 60 days. VS and TPH removal showed 5.2~8.3% and 67~74% respectively, and the reduction of VS until 30 day charged 70% of the total reduction. BMP test showed 27.77~30.46 mL $CH_4$/g VS and total methane production from total screened soil for remediation is expected about 260.4 $CH_4$ ton. Expected amount of methane production of the screened soil by landfarming application is 12.9 $CH_4$ ton, which shows 95% gas reduction effect and landfarming is effective for the reduction of methane production from screened soil of landfill.