A pretreatment process for hydrogen peroxide （H2O2） was optimized to enhance the biodegradation performance of rice straw and increase biogas yield. A determination experiment was conducted under predicted optimal c...A pretreatment process for hydrogen peroxide （H2O2） was optimized to enhance the biodegradation performance of rice straw and increase biogas yield. A determination experiment was conducted under predicted optimal conditions. Optimization was implemented using response surface methodology. The effects of biodegradation and the interactive effects of pretreatment time （PT）, H2O2 concentration （HC）, and substrate to inoculum ratio （S/I） on methane yield were investigated. The lignin, cellulose, and hemicellulose of rice straw were significantly degraded with increasing HC. The optimal conditions for the use of pretreated rice straw in anaerobic digestion were a 6.18-d PT, 2.68% HC （w/w total solid）, and 1.08 S/I; these conditions result in a methane yield of 288 mL g-1 volatile solids （VS）. A determination coefficient of 95.2% was obtained, indicating that the model used to predict the anabolic digestion process has a favorable fit with the experimental parameters. The determination experiment resulted in a methane yield of 290 mL g-1 VS, 88.0% higher than that of untreated rice straw. Thus, H2O2 pretreatment of rice straw can be used to improve methane yields during biogas production.展开更多
Coke oven gas(COG)is one of the most important by-products in steel industry,and the conversion of COG to value-added products has attracted much attention from both economic and environmental views.In this work,we us...Coke oven gas(COG)is one of the most important by-products in steel industry,and the conversion of COG to value-added products has attracted much attention from both economic and environmental views.In this work,we use the chemical looping reforming technology to produce pure H_(2)from COG.A series of La1-xSrxFeO_(3)(x?0,0.2,0.3,0.4,0.5,0.6)perovskite oxides were prepared as oxygen carriers for this purpose.The reduction behaviors of La1-xSrxFeO_(3)perovskite by different reducing gases(H_(2),CO,CH4 and the mixed gases)are investigated to discuss the competition effect of different components in COG for reacting with the oxygen carriers.The results show that reduction temperatures of H_(2)and CO are much lower than that of CH4,and high temperatures(>800℃)are requested for selective oxidation of methane to syngas.The co-existence of CO and H_(2)shows weak effect on the equilibrium of methane conversion at high temperatures,but the oxidation of methane to syngas can inhibit the consumption of CO and H_(2).The doping of suitable amounts of Sr in LaFeO_(3)perovskite(e.g.,La0.5Sr0.5FeO_(3))significantly promotes the activity for selective oxidation of methane to syngas and inhibits the formation of carbon deposition,obtaining both high methane conversion in the COG oxidation step and high hydrogen yield in the water splitting step.The La0.5Sr0.5FeO_(3)shows the highest methane conversion(67.82%),hydrogen yield(3.34 mmol g^(-1))and hydrogen purity(99.85%).The hydrogen yield in water splitting step is treble as high as the hydrogen consumption in reduction step.These results reveal that chemical looping reforming of COG to produce pure H_(2)is feasible,and an O_(2)-assistant chemical looping reforming process can further improves the redox stability of oxygen carrier.展开更多
The effects of initial substrate (5-60 g /L) and biomass concentration (0.5-3 g /L) on fermentative hydrogen production by mixed cultures were investigated in batch tests using glucose as substrate.The experimental re...The effects of initial substrate (5-60 g /L) and biomass concentration (0.5-3 g /L) on fermentative hydrogen production by mixed cultures were investigated in batch tests using glucose as substrate.The experimental results showed that the hydrogen production increases as the initial substrate concentration increases from 0 to 25 g /L.It indicated that the shift in the metabolic pathway or in the composition of the bacterial flora occurs.The maximum hydrogen yield of 1.78 mol /mol-glucose is obtained at the substrate concentration of 15 g /L.This study also shows that initial biomass concentration affects the hydrogen yield as the cumulative hydrogen production has been increased with the increase of initial cell concentration up to 1.5 g /L and reached the highest level.The maximum hydrogen yield is obtained at the cell concentration of 1.5 g /L.It indicated that the optimum biomass /substrate ratio,maximizing the hydrogen yield and the hydrogen production rate,is determined to be 0.1 g biomass /g glucose.展开更多
The effects of chloride salts(NaCl,MgCl2and NH4Cl)on the hydrolysis kinetics of MgH2prepared by hydridingcombustion synthesis and mechanical milling(HCS+MM)were discussed.X-ray diffraction(XRD)analyses show that high-...The effects of chloride salts(NaCl,MgCl2and NH4Cl)on the hydrolysis kinetics of MgH2prepared by hydridingcombustion synthesis and mechanical milling(HCS+MM)were discussed.X-ray diffraction(XRD)analyses show that high-purityMgH2was successfully prepared by HCS.Hydrolysis performance test results indicate that the chloride salt added during the millingprocess is favorable to the initial reaction rate and hydrogen generation yield within60min.A MgH2?10%NH4Cl composite exhibitsthe best performance with the hydrogen generation yield of1311mL/g and a conversion rate of85.69%in60min at roomtemperature.It is suggested that the chloride salts not only play as grinding aids in the milling process,but also create fresh surface ofreactive materials,favoring the hydrolysis reaction.展开更多
Pyrolysis of bagasse followed by thermal cracking of tar was carded out at atmospheric pressure using a dual bed reactor. The first bed was used for the pyrolysis and the second bed was used for thermal cracking of ta...Pyrolysis of bagasse followed by thermal cracking of tar was carded out at atmospheric pressure using a dual bed reactor. The first bed was used for the pyrolysis and the second bed was used for thermal cracking of tar. Iron fillings were used as the packed bed material in the second bed. The effects of reaction time （20 to 40 rain）, reactor temperature （600 to 900 ℃） and packed bed height （40-100 mm） on the product （char, tar and gas） yield and gas （H2, CO, CO2, CH4, CnHm） composition were studied. Over the ranges of the experimental conditions used, the operating conditions were optimized for pyrolysis temperature around 850 ℃, a reaction time of 30 min and packed bed height of 100 mm, thus we could obtain a gas richer in hydrogen and carbon monoxide and poorer in carbon dioxide and hydrocarbons. It was observed that compared with single bed process, dual bed process increased the gas yield from 0.397 to 0.750 m3/kg and decreased the tar yield from 0.445 to 0.268 g/g while the heating value of the product gas remained almost constant （10-11 M J/m3）.展开更多
基金financially supported by the Key Technologies R&D Program of China during the 11th Five-Year Plan period (2011BAD15B03)the Basic Scientific Fund of Northwest A&F University of China (QM2012002)
文摘A pretreatment process for hydrogen peroxide （H2O2） was optimized to enhance the biodegradation performance of rice straw and increase biogas yield. A determination experiment was conducted under predicted optimal conditions. Optimization was implemented using response surface methodology. The effects of biodegradation and the interactive effects of pretreatment time （PT）, H2O2 concentration （HC）, and substrate to inoculum ratio （S/I） on methane yield were investigated. The lignin, cellulose, and hemicellulose of rice straw were significantly degraded with increasing HC. The optimal conditions for the use of pretreated rice straw in anaerobic digestion were a 6.18-d PT, 2.68% HC （w/w total solid）, and 1.08 S/I; these conditions result in a methane yield of 288 mL g-1 volatile solids （VS）. A determination coefficient of 95.2% was obtained, indicating that the model used to predict the anabolic digestion process has a favorable fit with the experimental parameters. The determination experiment resulted in a methane yield of 290 mL g-1 VS, 88.0% higher than that of untreated rice straw. Thus, H2O2 pretreatment of rice straw can be used to improve methane yields during biogas production.
基金supported by the National Key R&D Program of China(2018YFB0605401)National Natural Science Foundation of China(Nos.51774159 and 51604137)the Qinglan Project of Kunming University of Science and Technology.
文摘Coke oven gas(COG)is one of the most important by-products in steel industry,and the conversion of COG to value-added products has attracted much attention from both economic and environmental views.In this work,we use the chemical looping reforming technology to produce pure H_(2)from COG.A series of La1-xSrxFeO_(3)(x?0,0.2,0.3,0.4,0.5,0.6)perovskite oxides were prepared as oxygen carriers for this purpose.The reduction behaviors of La1-xSrxFeO_(3)perovskite by different reducing gases(H_(2),CO,CH4 and the mixed gases)are investigated to discuss the competition effect of different components in COG for reacting with the oxygen carriers.The results show that reduction temperatures of H_(2)and CO are much lower than that of CH4,and high temperatures(>800℃)are requested for selective oxidation of methane to syngas.The co-existence of CO and H_(2)shows weak effect on the equilibrium of methane conversion at high temperatures,but the oxidation of methane to syngas can inhibit the consumption of CO and H_(2).The doping of suitable amounts of Sr in LaFeO_(3)perovskite(e.g.,La0.5Sr0.5FeO_(3))significantly promotes the activity for selective oxidation of methane to syngas and inhibits the formation of carbon deposition,obtaining both high methane conversion in the COG oxidation step and high hydrogen yield in the water splitting step.The La0.5Sr0.5FeO_(3)shows the highest methane conversion(67.82%),hydrogen yield(3.34 mmol g^(-1))and hydrogen purity(99.85%).The hydrogen yield in water splitting step is treble as high as the hydrogen consumption in reduction step.These results reveal that chemical looping reforming of COG to produce pure H_(2)is feasible,and an O_(2)-assistant chemical looping reforming process can further improves the redox stability of oxygen carrier.
基金Sponsored by the State Key Laboratory of Urban Water Resource and Environment of Harbin Institute of Technology(Grant No.2010DX06)the National High Technology Research and Development Program of China(Grant No.2006AA05Z109)the Harbin Science and Technology Bureau(Grant No.2009RFXXS004)
文摘The effects of initial substrate (5-60 g /L) and biomass concentration (0.5-3 g /L) on fermentative hydrogen production by mixed cultures were investigated in batch tests using glucose as substrate.The experimental results showed that the hydrogen production increases as the initial substrate concentration increases from 0 to 25 g /L.It indicated that the shift in the metabolic pathway or in the composition of the bacterial flora occurs.The maximum hydrogen yield of 1.78 mol /mol-glucose is obtained at the substrate concentration of 15 g /L.This study also shows that initial biomass concentration affects the hydrogen yield as the cumulative hydrogen production has been increased with the increase of initial cell concentration up to 1.5 g /L and reached the highest level.The maximum hydrogen yield is obtained at the cell concentration of 1.5 g /L.It indicated that the optimum biomass /substrate ratio,maximizing the hydrogen yield and the hydrogen production rate,is determined to be 0.1 g biomass /g glucose.
基金Projects(51571112,51171079,51471087) supported by the National Natural Science Foundation of ChinaProject(13KJA430003) supported by Jiangsu Higher Education Institutions of China+1 种基金Project supported by Qing Lan Project,ChinaProject supported by the Priority Academic Program Development(PAPD) of Jiangsu Higher Education Institutions,China
文摘The effects of chloride salts(NaCl,MgCl2and NH4Cl)on the hydrolysis kinetics of MgH2prepared by hydridingcombustion synthesis and mechanical milling(HCS+MM)were discussed.X-ray diffraction(XRD)analyses show that high-purityMgH2was successfully prepared by HCS.Hydrolysis performance test results indicate that the chloride salt added during the millingprocess is favorable to the initial reaction rate and hydrogen generation yield within60min.A MgH2?10%NH4Cl composite exhibitsthe best performance with the hydrogen generation yield of1311mL/g and a conversion rate of85.69%in60min at roomtemperature.It is suggested that the chloride salts not only play as grinding aids in the milling process,but also create fresh surface ofreactive materials,favoring the hydrolysis reaction.
文摘Pyrolysis of bagasse followed by thermal cracking of tar was carded out at atmospheric pressure using a dual bed reactor. The first bed was used for the pyrolysis and the second bed was used for thermal cracking of tar. Iron fillings were used as the packed bed material in the second bed. The effects of reaction time （20 to 40 rain）, reactor temperature （600 to 900 ℃） and packed bed height （40-100 mm） on the product （char, tar and gas） yield and gas （H2, CO, CO2, CH4, CnHm） composition were studied. Over the ranges of the experimental conditions used, the operating conditions were optimized for pyrolysis temperature around 850 ℃, a reaction time of 30 min and packed bed height of 100 mm, thus we could obtain a gas richer in hydrogen and carbon monoxide and poorer in carbon dioxide and hydrocarbons. It was observed that compared with single bed process, dual bed process increased the gas yield from 0.397 to 0.750 m3/kg and decreased the tar yield from 0.445 to 0.268 g/g while the heating value of the product gas remained almost constant （10-11 M J/m3）.
