The methane concentration profile from -1.5m depth in soil to 32m height in air was measured in alpine steppe lo-cated in the permafrost area. Methane concentrations showed widely variations both in air and in soil du...The methane concentration profile from -1.5m depth in soil to 32m height in air was measured in alpine steppe lo-cated in the permafrost area. Methane concentrations showed widely variations both in air and in soil during the study period. The mean concentrations in atmosphere were all higher than those in soil, and the highest methane concentration was found in air at the height of 16m with the lowest concentration occur-ring at the depth of 1.5m in soil. The variations of atmospheric methane concentrations did not show any clear pattern both temporally and spatially, although they exhibited a more steady-stable state than those in soil. During the seasonal variations, the methane concentrations at different depths in soil were sig-nificantly correlated (R2>0.6) with each other comparing to the weak correlations (R2<0.2) between the atmospheric concentra-tions at different heights. Mean methane concentrations in soil significantly decreased with depth. This was the compositive influence of the decreasing production rates and the increasing methane oxidation rates, which was caused by the descent soil moisture with depth. Although the methane concentrations at all depths varied widely during the growing season, they showed very distinct temporal variations in the non-growing season. It was indicated from the literatures that methane oxidation rates were positively correlated with soil temperature. The higher methane concentrations in soil during the winter were deter-mined by the lower methane oxidation rates with decreasing soil temperatures, whereas methane production rates had no reaction to the lower temperature. Relations between methane contribution and other environmental factors were not discussed in this paper for lacking of data, which impulse us to carry out further and more detailed studies in this unique area.展开更多
High-precision methane gas detection is of great importance in industrial safety, energy production and environmental protection, etc. However, in the existing measurement techniques, the methane gas concentration inf...High-precision methane gas detection is of great importance in industrial safety, energy production and environmental protection, etc. However, in the existing measurement techniques, the methane gas concentration information is susceptible to noise, which leads to its useful signal being drowned by noise. A fusion algorithm of variational modal decomposition(VMD) and improved wavelet threshold filtering is proposed, which is used in combination with tunable diode laser absorption spectroscopy(TDLAS) to implement a non-contact, high-resolution methane gas concentration detection. The fusion algorithm can perform noise reduction and further segmentation of the methane gas detection signal. And the simulation and experiment verify the effectiveness of the fusion algorithm, and the experimental results show that for the detection of air containing 10 ppm, 30 ppm, 60 ppm, 80 ppm, and 99 ppm methane, the errors are 12.75%, 8.18%, 3.37%, 2.46%, and 1.78%, respectively.展开更多
This study was conducted at three rivers of the Chaohu Lake watershed during the summer season of 2008,aiming to investigate the diurnal variations of dissolved CH4 concentrations and emissions,as well as the dynamics...This study was conducted at three rivers of the Chaohu Lake watershed during the summer season of 2008,aiming to investigate the diurnal variations of dissolved CH4 concentrations and emissions,as well as the dynamics of CH4 accumulation emission rates over consecutive 72 h.The results showed that CH4 concentrations in the Fengle,Hangbu,and Nanfei rivers ranged from 56.33-124.79,160.82-341.03,and 213.49-716.81 nmol L-1,respectively,over a daily cycle;while the saturation of CH4 ranged from 188.72-418.07,538.74-1 142.46,and 715.23-2 401.38%,respectively,which indicated that surface waters were in all cases oversaturated with respect to the atmosphere.An obvious diurnal variation pattern of the dissolved CH4 concentrations demonstrated a higher value during daytime but a lower value for night time.Additionally,the highest dissolved CH4 concentrations were detected in the Nanfei River which received substantial urban wastewater discharges.CH4 emissions measured with floating chambers ranged from 5.82-15.46,5.77-8.41,and 13.51-49.25 mg C m-2 h-1 for the Fengle,Hangbu,and Nanfei rivers,respectively,over a daily cycle.Significantly higher CH4 emissions were also observed from the Nanfei River.The accumulative CH4 emissions for each river increased with time,while a decline trend on the accumulation rates was investigated over the consecutive 72 h.展开更多
To improve the precision and reliability in predicting methane hazard in working face of coal mine, we have proposed a forecasting and forewarning model for methane hazard based on the least square support vector (LS-...To improve the precision and reliability in predicting methane hazard in working face of coal mine, we have proposed a forecasting and forewarning model for methane hazard based on the least square support vector (LS-SVM) multi-classifier and regression machine. For the forecasting model, the methane concentration can be considered as a nonlinear time series and the time series analysis method is adopted to predict the change in methane concentration using LS-SVM regression. For the forewarning model, which is based on the forecasting results, by the multi-classification method of LS-SVM, the methane hazard was identified to four grades: normal, attention, warning and danger. According to the forewarning results, corresponding measures are taken. The model was used to forecast and forewarn the K9 working face. The results obtained by LS-SVM regression show that the forecast- ing have a high precision and forewarning results based on a LS-SVM multi-classifier are credible. Therefore, it is an effective model building method for continuous prediction of methane concentration and hazard forewarning in working face.展开更多
The chemical looping reforming of methane through the nonstoichiometric ceria redox cycle(CeO2/CeO2-δ) has been experimentally investigated in a directly irradiated solar reactor to convert both solar energy and meth...The chemical looping reforming of methane through the nonstoichiometric ceria redox cycle(CeO2/CeO2-δ) has been experimentally investigated in a directly irradiated solar reactor to convert both solar energy and methane to syngas in the temperature range 900–1050 °C. Experiments were carried out with different ceria shapes via two-step redox cycling composed of endothermic partial reduction of ceria with methane and complete exothermic re-oxidation of reduced ceria with H2 O/CO2 at the same operating temperature, thereby demonstrating the capability to operate the cycle isothermally. A parametric study considering different ceria macrostructure variants(ceria packed powder, ceria packed powder mixed with inert Al2 O3 particles, and ceria reticulated porous foam) and operating parameters(methane flow-rate, reduction temperature, or sintering temperature) was conducted in order to unravel their impact on the bed-averaged oxygen non-stoichiometry(δ), syngas yield, methane conversion, and solar reactor performance. The ceria cycling stability was also experimentally investigated to demonstrate repeatable syngas production by alternating the flow between CH4 and H2 O(or CO2). A decrease in sintering temperature of the ceria foam was beneficial for increasing syngas selectivity, methane conversion,and reactor performance. Increasing both CH4 concentration and reduction temperature enhanced δ with the maximum value up to 0.41 but concomitantly favored CH4 cracking reaction. The ceria reticulated porous foam showed better performance in terms of effective heat transfer, due to volumetric absorption of concentrated solar radiation and uniform heating with lower solar power consumption, thereby promoting the solar-to-fuel energy conversion efficiency that reached up to 5.60%. The energy upgrade factor achieved during cycle was up to 1.19. Stable patterns in the δ and syngas yield for consecutive cycles with the ceria foam validated material performance stability.展开更多
To exploit an effective adsorbent to separate hydrogen and methane, microporous titanium silicate molecular sieve NaETS-4 was synthesized and modified by strontium. The adsorption characteristics and diffusion behavio...To exploit an effective adsorbent to separate hydrogen and methane, microporous titanium silicate molecular sieve NaETS-4 was synthesized and modified by strontium. The adsorption characteristics and diffusion behaviors of the prepared titanosilicate molecular sieve were studied by concentration pulse chromatography. And the effects of ion-exchange and dehydration temperature on adsorbent structure and gas diffusion were also discussed. The results showed that the thermal stability and Henry＇s Law constants were enhanced and micropore diffusivity decreased after exchanging Na＋ with Sr2＋. With the increase of dehydration temperature, Henry＇s Law constant and micropore diffusivity of CI-I4 decreased in both NaETS-4 and SrETS-4. While for 1-12 in SrETS-4, the increase of Henry＇s Law constant and the decrease of diffusion rate can be attributed to the shrinks of pore diameter resulting from the relocation of Sr2＋. Correspondingly, the kinetic selectivity of H2/CH4 reached 8.91 indicating its potentiality in separating H2 and CH4.展开更多
Work face 3312 of coal mining in a colliery was taken as an example in which methane data in a series of locations was analyzed.For the purpose of data analysis, work face 3312 was divided into sections with 20 powere...Work face 3312 of coal mining in a colliery was taken as an example in which methane data in a series of locations was analyzed.For the purpose of data analysis, work face 3312 was divided into sections with 20 powered supports and some measur- ing-points in a section.Through analysis based on the sectional control volume model,the following points are concluded: (1) the location of gob air flow begins flow into coal face in 70 m away from the haulage gallery;(2) in the control volumes No.10 and No.30,the ra- tios of methane intensity from coal face into gob to the methane intensity in the corre- sponding control volume are 30% and 22%;(3) in the control volume No.50 to No.110,the ratios of methane intensity from gob into coal face to the methane intensity in the corre- sponding control volume are 4%,17%,22% and 53%,respectively.展开更多
It is important to study the methane transport phenomenon in a longwall panel under descensional ventilation conditions. In this paper the gob area is divided into a number of nodes to represent the rectangular percol...It is important to study the methane transport phenomenon in a longwall panel under descensional ventilation conditions. In this paper the gob area is divided into a number of nodes to represent the rectangular percolating elements. The connections between nodes (elements) become branches,so that a network can be formed. Using the mechanics of porous media fluid flow, the mathematical model of air and gas flows has been established. Based on the existing ground pressure theories,the porosity of the inhomogeneous porous media in the gob can be given. In computer simulation it is considered that air pressure and temperature are functions of position ; air density, viscosity, and natural ventilation pressure are functions of temperature,pressure and methane concentration,and the resistance varies with air density and viscosity. Finally,the calculation results are given to show the differences between ascensional and descensional ventilation methods.展开更多
Methane,a potent greenhouse gas with a global warming potential significantly higher than carbon dioxide,plays a critical role in climate change.Accurate predictions of its future concentrations are vital for understa...Methane,a potent greenhouse gas with a global warming potential significantly higher than carbon dioxide,plays a critical role in climate change.Accurate predictions of its future concentrations are vital for understanding and mitigating its environmental impact.For this reason,this paper presents a comparative analysis of deep learning models—Long Short-Term Memory(LSTM),Gated Recurrent Unit(GRU),CNN(Convolutional Neural Network)-GRU,and CNN-LSTM—for forecasting atmospheric methane concentrations through 2050.Leveraging historical data,each model's performance was evaluated using key metrics,including Mean Absolute Error(MAE)and Nash-Sutcliffe Efficiency(NSE).The results reveal that the CNNLSTM model achieved the highest accuracy,with the lowest MAE of 0.6567 and the highest NSE score of 0.933,indicating its superior capability in capturing the complexities of methane concentration trends.In contrast,the GRU model exhibited the poorest performance,with an MAE of 0.9667 and an NSE score of 0.844.Projections for 2050 indicate significant increases in methane levels,with maximum yearly concentrations expected to reach up to 2199.76 ppb,particularly under the CNN-LSTM model.These findings underscore the potential risks associated with rising methane concentrations,which could exacerbate global warming and its associated impacts.The study highlights the importance of employing advanced predictive models like CNN-LSTM to inform and enhance global climate change mitigation strategies.展开更多
The activities of 25%(mass fraction,w)Mo O3/Al2O3 and 5%(w)Co O-25%Mo O3/Al2O3 catalysts in a sulfur-resistant methanation process were examined as the concentration of H2 S was varied from 0 to 12 m L·L^-1(volum...The activities of 25%(mass fraction,w)Mo O3/Al2O3 and 5%(w)Co O-25%Mo O3/Al2O3 catalysts in a sulfur-resistant methanation process were examined as the concentration of H2 S was varied from 0 to 12 m L·L^-1(volume fractionφ=0.00%-1.20%).The results showed that the catalytic activity of 5%Co O-25%Mo O3/Al2O3 catalyst increased steadily as the concentration of H2 S increased.However,the catalytic performance of the25%Mo O3/Al2O3 catalyst was insensitive to the H2 S concentration.Co was found to benefit the 25%Mo O3/Al2O3 catalyst when H2 S concentration was greater than 0.40%(φ).Below this threshold,addition of Co to the catalyst matrix inhibited the activity of the 25%Mo O3/Al2O3 catalyst.N2-physisorption(BET)and X-ray diffraction(XRD)analyses were used to characterize the fresh and used catalysts.The results indicated that exposure to H2 S at various concentrations did not significantly affect the physical structure of the catalysts,but it will affect the active phase through metal sulfides.The results provide the appropriate range of H2 S concentration to add Co as promoter for 25%Mo O3/Al2O3 catalyst,which is likely to be useful for industrial catalyst selection.展开更多
In coal mines in such countries as China and Russia,most of the coal mine methane(CMM) generated during mining is emitted to the atmosphere without any effective usage,because the methane concentration of CMM is relat...In coal mines in such countries as China and Russia,most of the coal mine methane(CMM) generated during mining is emitted to the atmosphere without any effective usage,because the methane concentration of CMM is relatively low and not allowed to be used as fuel for safety reasons.Methane is one of the greenhouse gases.Therefore,if it becomes possible to concentrate CMM to an acceptable level for use as fuel,this will greatly contribute to reduction of greenhouse gas emissions.With the aim of gaining approval as a greenhouse gas emission reduction of the clean development mechanism(CDM) or joint implementation(JI) project,we developed a CMM concentration system to apply the vacuum pressure swing adsorption(VPSA) technology using a high methane-selective adsorbent by Osaka Gas Co.,Ltd.The pilot-scale plant of a CMM concentration system was installed in a coal mine in Fuxin City in the northeastern China and a demonstration test was commenced in December 2008.As the result,the pilot-scale plant successfully concentrated the raw material gas with a methane concentration of 21% and a flow rate of 1000 Nm3/h to 48%,which exceeded the target of the methane concentration performance(a 25% increase).The methane recovery rate reached 93%.展开更多
基金funded by The National Basic Research Program (Grant No. G1998040800)Pre-studies project of National Basic Research Program (Grant No. 2005CCA05500)
文摘The methane concentration profile from -1.5m depth in soil to 32m height in air was measured in alpine steppe lo-cated in the permafrost area. Methane concentrations showed widely variations both in air and in soil during the study period. The mean concentrations in atmosphere were all higher than those in soil, and the highest methane concentration was found in air at the height of 16m with the lowest concentration occur-ring at the depth of 1.5m in soil. The variations of atmospheric methane concentrations did not show any clear pattern both temporally and spatially, although they exhibited a more steady-stable state than those in soil. During the seasonal variations, the methane concentrations at different depths in soil were sig-nificantly correlated (R2>0.6) with each other comparing to the weak correlations (R2<0.2) between the atmospheric concentra-tions at different heights. Mean methane concentrations in soil significantly decreased with depth. This was the compositive influence of the decreasing production rates and the increasing methane oxidation rates, which was caused by the descent soil moisture with depth. Although the methane concentrations at all depths varied widely during the growing season, they showed very distinct temporal variations in the non-growing season. It was indicated from the literatures that methane oxidation rates were positively correlated with soil temperature. The higher methane concentrations in soil during the winter were deter-mined by the lower methane oxidation rates with decreasing soil temperatures, whereas methane production rates had no reaction to the lower temperature. Relations between methane contribution and other environmental factors were not discussed in this paper for lacking of data, which impulse us to carry out further and more detailed studies in this unique area.
基金supported by the Project Grant from Heilongjiang Bayi Agricultural Reclamation University,Heilongjiang,China (No.XDB201813)。
文摘High-precision methane gas detection is of great importance in industrial safety, energy production and environmental protection, etc. However, in the existing measurement techniques, the methane gas concentration information is susceptible to noise, which leads to its useful signal being drowned by noise. A fusion algorithm of variational modal decomposition(VMD) and improved wavelet threshold filtering is proposed, which is used in combination with tunable diode laser absorption spectroscopy(TDLAS) to implement a non-contact, high-resolution methane gas concentration detection. The fusion algorithm can perform noise reduction and further segmentation of the methane gas detection signal. And the simulation and experiment verify the effectiveness of the fusion algorithm, and the experimental results show that for the detection of air containing 10 ppm, 30 ppm, 60 ppm, 80 ppm, and 99 ppm methane, the errors are 12.75%, 8.18%, 3.37%, 2.46%, and 1.78%, respectively.
基金supported by the National Natural Science Foundation of China(20777073)
文摘This study was conducted at three rivers of the Chaohu Lake watershed during the summer season of 2008,aiming to investigate the diurnal variations of dissolved CH4 concentrations and emissions,as well as the dynamics of CH4 accumulation emission rates over consecutive 72 h.The results showed that CH4 concentrations in the Fengle,Hangbu,and Nanfei rivers ranged from 56.33-124.79,160.82-341.03,and 213.49-716.81 nmol L-1,respectively,over a daily cycle;while the saturation of CH4 ranged from 188.72-418.07,538.74-1 142.46,and 715.23-2 401.38%,respectively,which indicated that surface waters were in all cases oversaturated with respect to the atmosphere.An obvious diurnal variation pattern of the dissolved CH4 concentrations demonstrated a higher value during daytime but a lower value for night time.Additionally,the highest dissolved CH4 concentrations were detected in the Nanfei River which received substantial urban wastewater discharges.CH4 emissions measured with floating chambers ranged from 5.82-15.46,5.77-8.41,and 13.51-49.25 mg C m-2 h-1 for the Fengle,Hangbu,and Nanfei rivers,respectively,over a daily cycle.Significantly higher CH4 emissions were also observed from the Nanfei River.The accumulative CH4 emissions for each river increased with time,while a decline trend on the accumulation rates was investigated over the consecutive 72 h.
基金Project 50674111 supported by the National Natural Science Foundation of China
文摘To improve the precision and reliability in predicting methane hazard in working face of coal mine, we have proposed a forecasting and forewarning model for methane hazard based on the least square support vector (LS-SVM) multi-classifier and regression machine. For the forecasting model, the methane concentration can be considered as a nonlinear time series and the time series analysis method is adopted to predict the change in methane concentration using LS-SVM regression. For the forewarning model, which is based on the forecasting results, by the multi-classification method of LS-SVM, the methane hazard was identified to four grades: normal, attention, warning and danger. According to the forewarning results, corresponding measures are taken. The model was used to forecast and forewarn the K9 working face. The results obtained by LS-SVM regression show that the forecast- ing have a high precision and forewarning results based on a LS-SVM multi-classifier are credible. Therefore, it is an effective model building method for continuous prediction of methane concentration and hazard forewarning in working face.
基金The King Mongkut’s Institute of Technology Ladkrabang(KMITL),Thailandthe Franco-Thai scholarship program。
文摘The chemical looping reforming of methane through the nonstoichiometric ceria redox cycle(CeO2/CeO2-δ) has been experimentally investigated in a directly irradiated solar reactor to convert both solar energy and methane to syngas in the temperature range 900–1050 °C. Experiments were carried out with different ceria shapes via two-step redox cycling composed of endothermic partial reduction of ceria with methane and complete exothermic re-oxidation of reduced ceria with H2 O/CO2 at the same operating temperature, thereby demonstrating the capability to operate the cycle isothermally. A parametric study considering different ceria macrostructure variants(ceria packed powder, ceria packed powder mixed with inert Al2 O3 particles, and ceria reticulated porous foam) and operating parameters(methane flow-rate, reduction temperature, or sintering temperature) was conducted in order to unravel their impact on the bed-averaged oxygen non-stoichiometry(δ), syngas yield, methane conversion, and solar reactor performance. The ceria cycling stability was also experimentally investigated to demonstrate repeatable syngas production by alternating the flow between CH4 and H2 O(or CO2). A decrease in sintering temperature of the ceria foam was beneficial for increasing syngas selectivity, methane conversion,and reactor performance. Increasing both CH4 concentration and reduction temperature enhanced δ with the maximum value up to 0.41 but concomitantly favored CH4 cracking reaction. The ceria reticulated porous foam showed better performance in terms of effective heat transfer, due to volumetric absorption of concentrated solar radiation and uniform heating with lower solar power consumption, thereby promoting the solar-to-fuel energy conversion efficiency that reached up to 5.60%. The energy upgrade factor achieved during cycle was up to 1.19. Stable patterns in the δ and syngas yield for consecutive cycles with the ceria foam validated material performance stability.
基金supported by Yunnan Natural Science Foundation(No.2010CD026)Kunming University of Science and Technology Science Foundation(No.kkz3201205022)+1 种基金Analysis and Testing Foundation of Kunming University of Science and Technology(20140805)the National Natural Science Foundation of China(No.21301079)
文摘To exploit an effective adsorbent to separate hydrogen and methane, microporous titanium silicate molecular sieve NaETS-4 was synthesized and modified by strontium. The adsorption characteristics and diffusion behaviors of the prepared titanosilicate molecular sieve were studied by concentration pulse chromatography. And the effects of ion-exchange and dehydration temperature on adsorbent structure and gas diffusion were also discussed. The results showed that the thermal stability and Henry＇s Law constants were enhanced and micropore diffusivity decreased after exchanging Na＋ with Sr2＋. With the increase of dehydration temperature, Henry＇s Law constant and micropore diffusivity of CI-I4 decreased in both NaETS-4 and SrETS-4. While for 1-12 in SrETS-4, the increase of Henry＇s Law constant and the decrease of diffusion rate can be attributed to the shrinks of pore diameter resulting from the relocation of Sr2＋. Correspondingly, the kinetic selectivity of H2/CH4 reached 8.91 indicating its potentiality in separating H2 and CH4.
文摘Work face 3312 of coal mining in a colliery was taken as an example in which methane data in a series of locations was analyzed.For the purpose of data analysis, work face 3312 was divided into sections with 20 powered supports and some measur- ing-points in a section.Through analysis based on the sectional control volume model,the following points are concluded: (1) the location of gob air flow begins flow into coal face in 70 m away from the haulage gallery;(2) in the control volumes No.10 and No.30,the ra- tios of methane intensity from coal face into gob to the methane intensity in the corre- sponding control volume are 30% and 22%;(3) in the control volume No.50 to No.110,the ratios of methane intensity from gob into coal face to the methane intensity in the corre- sponding control volume are 4%,17%,22% and 53%,respectively.
文摘It is important to study the methane transport phenomenon in a longwall panel under descensional ventilation conditions. In this paper the gob area is divided into a number of nodes to represent the rectangular percolating elements. The connections between nodes (elements) become branches,so that a network can be formed. Using the mechanics of porous media fluid flow, the mathematical model of air and gas flows has been established. Based on the existing ground pressure theories,the porosity of the inhomogeneous porous media in the gob can be given. In computer simulation it is considered that air pressure and temperature are functions of position ; air density, viscosity, and natural ventilation pressure are functions of temperature,pressure and methane concentration,and the resistance varies with air density and viscosity. Finally,the calculation results are given to show the differences between ascensional and descensional ventilation methods.
文摘Methane,a potent greenhouse gas with a global warming potential significantly higher than carbon dioxide,plays a critical role in climate change.Accurate predictions of its future concentrations are vital for understanding and mitigating its environmental impact.For this reason,this paper presents a comparative analysis of deep learning models—Long Short-Term Memory(LSTM),Gated Recurrent Unit(GRU),CNN(Convolutional Neural Network)-GRU,and CNN-LSTM—for forecasting atmospheric methane concentrations through 2050.Leveraging historical data,each model's performance was evaluated using key metrics,including Mean Absolute Error(MAE)and Nash-Sutcliffe Efficiency(NSE).The results reveal that the CNNLSTM model achieved the highest accuracy,with the lowest MAE of 0.6567 and the highest NSE score of 0.933,indicating its superior capability in capturing the complexities of methane concentration trends.In contrast,the GRU model exhibited the poorest performance,with an MAE of 0.9667 and an NSE score of 0.844.Projections for 2050 indicate significant increases in methane levels,with maximum yearly concentrations expected to reach up to 2199.76 ppb,particularly under the CNN-LSTM model.These findings underscore the potential risks associated with rising methane concentrations,which could exacerbate global warming and its associated impacts.The study highlights the importance of employing advanced predictive models like CNN-LSTM to inform and enhance global climate change mitigation strategies.
文摘The activities of 25%(mass fraction,w)Mo O3/Al2O3 and 5%(w)Co O-25%Mo O3/Al2O3 catalysts in a sulfur-resistant methanation process were examined as the concentration of H2 S was varied from 0 to 12 m L·L^-1(volume fractionφ=0.00%-1.20%).The results showed that the catalytic activity of 5%Co O-25%Mo O3/Al2O3 catalyst increased steadily as the concentration of H2 S increased.However,the catalytic performance of the25%Mo O3/Al2O3 catalyst was insensitive to the H2 S concentration.Co was found to benefit the 25%Mo O3/Al2O3 catalyst when H2 S concentration was greater than 0.40%(φ).Below this threshold,addition of Co to the catalyst matrix inhibited the activity of the 25%Mo O3/Al2O3 catalyst.N2-physisorption(BET)and X-ray diffraction(XRD)analyses were used to characterize the fresh and used catalysts.The results indicated that exposure to H2 S at various concentrations did not significantly affect the physical structure of the catalysts,but it will affect the active phase through metal sulfides.The results provide the appropriate range of H2 S concentration to add Co as promoter for 25%Mo O3/Al2O3 catalyst,which is likely to be useful for industrial catalyst selection.
基金supported by the Project of Development of Methane Concen-tration Technology Aimed at Effective Use of Low-concentration CMM (Coal Methane Gas)the International Research Cooperation Project Implemented by the New Energy and Industrial Technology Development Organizationthe Cooperative Research Project Subsidies from the Ministry of Economy,Trade and Industry
文摘In coal mines in such countries as China and Russia,most of the coal mine methane(CMM) generated during mining is emitted to the atmosphere without any effective usage,because the methane concentration of CMM is relatively low and not allowed to be used as fuel for safety reasons.Methane is one of the greenhouse gases.Therefore,if it becomes possible to concentrate CMM to an acceptable level for use as fuel,this will greatly contribute to reduction of greenhouse gas emissions.With the aim of gaining approval as a greenhouse gas emission reduction of the clean development mechanism(CDM) or joint implementation(JI) project,we developed a CMM concentration system to apply the vacuum pressure swing adsorption(VPSA) technology using a high methane-selective adsorbent by Osaka Gas Co.,Ltd.The pilot-scale plant of a CMM concentration system was installed in a coal mine in Fuxin City in the northeastern China and a demonstration test was commenced in December 2008.As the result,the pilot-scale plant successfully concentrated the raw material gas with a methane concentration of 21% and a flow rate of 1000 Nm3/h to 48%,which exceeded the target of the methane concentration performance(a 25% increase).The methane recovery rate reached 93%.
