Ni-Cu/ZrO2-CeO2-Al2O3 catalysts were prepared by co-precipitation method at pH=9 and using Na2CO3 as the precipitant. The Ni loading （mass fraction） of the catalysts was 10%. The catalysts were characterized by X-ra...Ni-Cu/ZrO2-CeO2-Al2O3 catalysts were prepared by co-precipitation method at pH=9 and using Na2CO3 as the precipitant. The Ni loading （mass fraction） of the catalysts was 10%. The catalysts were characterized by X-ray diffraction, temperature-programmed oxidation （TPO）, scanning electron microscope （SEM）, and X-ray photoelectron spectroscopy （XPS）. The effects of calcined temperature of support on coke deposition were studied. TPO, SEM and XPS results indicated there was no peak of higher temperature oxygen consumption on Ni-Cu/ZrO2-CeO2-Al2O3 catalyst （support was calcined at 800 ℃）, which could lead to the deactivation of the catalyst. The carbon species were carbonate and inactive carbon （filamentous carbon species） on the surface of catalyst reacting for 40 h which perhaps led to the deactivation of the catalyst.展开更多
Ni catalysts supported on various mixed oxides of Al2O3 with rare earth oxide and transitional metal oxides were synthesized. The studies focused on the measurement of the autothermal reforming of methane to hydrogen ...Ni catalysts supported on various mixed oxides of Al2O3 with rare earth oxide and transitional metal oxides were synthesized. The studies focused on the measurement of the autothermal reforming of methane to hydrogen over Ni catalysts supported on the mixed oxide ZrxCe30-xAl70Oδ （x-=5, 10, 15）. The catalytic performance of Ni/Zr10Ce20Al70Oδ was better than that of other catalysts. XRD results showed that the addition of Zr to Ni/Ce30Al70Oδ prevented the formation of NiAl2O4 and facilitated the dispersion of NiO. Effects of CuO addition to Zr10Ce20Al70Oδ were also investigated. The activity of Ni catalyst supported on CuO-ZrO2-CeO2-Al2O3 was somewhat affected and the Ni/Cu5Zr10Ce20Al65Oδ showed the best catalytic performance with the highest CH4 conversion, yield of H2, selectivity for H2 and H2/CO production ratio in operation temperatures ranging from 650 to 750 ℃.展开更多
The transition metals （Cu, Co, and Fe） were applied to modify Ni/Ce0.2Zr0.1Al0.7Oδ catalyst. The effects of transition metals on the catalytic properties of Ni/Ce0.2Zr0.1Al0.7Oδ autothermal reforming of methane we...The transition metals （Cu, Co, and Fe） were applied to modify Ni/Ce0.2Zr0.1Al0.7Oδ catalyst. The effects of transition metals on the catalytic properties of Ni/Ce0.2Zr0.1Al0.7Oδ autothermal reforming of methane were investigated. The Ni-supported catalysts were characterized by XRD, TPR and XPS. Tests in autothermal reforming of methane to hydrogen showed that the addition of transition metals （Cu and Co） significantly increased the activity of catalyst under the conditions of lower reaction temperature, and Ni/Cu0.05Ce0.2Zr0.1Al0.65Oδ was found to have the highest conversion of CH4 among all catalysts in the operation temperatures ranging from 923 K to 1023 K. TPR, XRD and XPS measurements indicated that the cubic phases of CexZr1-xO2 solid solution were formed in the preparation process of catalysts. Strong interaction was found to exist between NiO and CexZr1-xO2 solid solution. The addition of Cu improved the dispersion of NiO, inhibited the formation of NiAl2O4, and thus significantly promoted the activity of the catalyst Ni/Cu0.05Ce0.2Zr0.1Al0.65Oδ展开更多
Ni catalysts supported on Al2O3, ZrO2-Al2O3, CeO2-Al2O3 and ZrO2-CeO2-Al2O3 were prepared by coprecipitation method, and their catalytic performances for autothermal reforming of methane to hydrogen were investigated....Ni catalysts supported on Al2O3, ZrO2-Al2O3, CeO2-Al2O3 and ZrO2-CeO2-Al2O3 were prepared by coprecipitation method, and their catalytic performances for autothermal reforming of methane to hydrogen were investigated. The Ni-supported catalysts were characterized by XRD, TPR and XPS. The relationship between the structures and catalytic activities of the catalysts was discussed. The results showed that the catalytic activity and stability of the Ni/ZrO2-CeO2-Al2O3 catalyst was better than those of other catalysts with the highest CH4 conversion, H2/CO and H2/COx ratio at 750 ℃. The catalyst showed a little deactivation along the reaction time during its 72 h on stream with the mean deactivation rate of 0.08%/h. The catalytic performance of the Ni/ZrO2-CeO2-Al2O3 catalyst was also affected by reaction temperature, no2 ： nCH4 molar ratio and nH2O ： nCH4 molar ratio. TPR, XRD and XPS measurements indicated that the formation of ZrO2-CeO2 solid solution could improve the dispersion of NiO, and inhibit the formation of NiAl2O3, and thus significantly promoted the catalytic activity of the Ni/ZrO2-CeO2-Al2O3 catalyst.展开更多
The effect of promoter Ce on the catalytic performance of Ni/Al2O3 catalyst for autothermal reforming of methane to hydrogen was investigated. The catalysts were characterized by X-ray diffraction （XRD）, temperature...The effect of promoter Ce on the catalytic performance of Ni/Al2O3 catalyst for autothermal reforming of methane to hydrogen was investigated. The catalysts were characterized by X-ray diffraction （XRD）, temperature-programmed reduction （TPR）, and X-ray photoelectron spectroscopy （XPS）. The results indicated that the catalytic performance of the catalysts was improved with the addition of Ce. Ni/Ce30Al70Oδ showed the highest CH4 conversion in operation temperatures ranging from 650 ℃ to 850 ℃. At the same time, the decrease in H2/CO ratio with increasing reaction temperature was consistent with the fact that water-gas shift reaction was thermodynamically unfavorable at higher temperatures. The XRD result indicated that adding Ce to Ni/Al2O3 catalyst prevented the formation of NiAl2O4 and facilitated the formation of NiO. The formation of NiO increased the number of active sites, resulting in higher activity. Comparing the TPR profiles of Ni/Ce30Al70Oδ with Ni/Al2O3, it could be clearly observed that with the addition of Ce, the total reduction peak areas in the middle and low temperatures increased. It was most probably that the addition of Ce inhibited the stronger interaction between Ni and Al2O3 to form the phase of NiAl2O4, and favored the formation of the strong interaction between NiO species and CeO2. Therefore, the addition of Ce to the Ni/Al2O3 catalyst increased the active surface that promoted the activity of the catalyst.展开更多
Autothermal reforming (ATR) is one of the leading methods for hydrogen production from hydrocar- bons. Liquefied petroleum gas, with propane as the main component, is a promising fuel for on-board hydrogen producing s...Autothermal reforming (ATR) is one of the leading methods for hydrogen production from hydrocar- bons. Liquefied petroleum gas, with propane as the main component, is a promising fuel for on-board hydrogen producing systems in fuel cell vehicles and for domestic fuel cell power generation devices. In this article, propane ATR process is studied and operation conditions are optimized with PRO/Ⅱ? from SIMSCI for proton exchange membrane fuel cell application. In the ATR system including water gas shift and preferential oxidation, heat in the hot streams and cold streams is controlled to be in balance. Different operation conditions are studied and drawn in contour plots. The region for ATR reforming with the highest efficiency can thus be identified. One operation point was chosen with the following process parameters: feed temperature for the ATR reactor is 425℃, steam to carbon ratio S/C is 2.08, air stoichiometry is 0.256. Thermal efficiency for the integrated system is calculated to be as high as 84.0 % with 38.27 % H2 and 3.2μl·L-1 CO in the product gas.展开更多
Biodegradation parameters and kinetic characteristics for pre-treating waste strains of Klebsiella pneu-moniae were studied in laboratory scale with an insulated reactor by an innovative technique,autothermal thermo-p...Biodegradation parameters and kinetic characteristics for pre-treating waste strains of Klebsiella pneu-moniae were studied in laboratory scale with an insulated reactor by an innovative technique,autothermal thermo-philic aerobic digestion(ATAD) . Based on an Arrhenius-type equation,an empirical model was developed to corre-late the removal of total suspended solid(TSS) with the initial TSS concentration,influent reaction temperature,aeration rate and stirring rate. The reaction temperatures of the ATAD system could be raised from the ambient temperatures of 25 °C to a maximum temperature of 65 °C. The exponentials for the initial TSS concentration,aeration rate and stirring rate were 1.579,-0.8175 and-0.6549,respectively,and the apparent activation energy was 6.8774 kJ·mol-1. The correlation coefficient for the pre-exponential factor was 0.9223. The TSS removal effi-ciency predicted by the model was validated with an actual test,showing a maximum relative deviation of 10.79%. The new model has a good practicability.展开更多
Hydrogen was produced over noble metal（Ir, Ru, Rh, Pd） catalysts supported on various oxides, including γ-Al2O3, CeO2, ZrO2 and La2O3, via the autothermal reforming reaction of ethanol （ATRE） and oxidative reform...Hydrogen was produced over noble metal（Ir, Ru, Rh, Pd） catalysts supported on various oxides, including γ-Al2O3, CeO2, ZrO2 and La2O3, via the autothermal reforming reaction of ethanol （ATRE） and oxidative reforming reaction of ethanol （OSRE）. The conversion of ethanol and selectivites for hydrogen and byproducts such as methane, ethylene and acetaldehyde were studied. It was found that lanthana alone possessed considerable activity for the ATRE reaction, which could be used as a functional support for ATRE catalysts. It was demonstrated that Ir/La2O3 prevented the formation of methane, and Rh/La2O3 encumbered the production of ethylene and acetaldehyde. ATRE reaction was carried out over La2O3-supported catalysts （Ir/La2O3） with good stability on stream, high conversion, and excellent hydrogen selectivity approaching thermodynamic limit under autothermal condition. Typically, 3.4H2 molecules can be extracted from a pair of ethanol and water molecules over Ir（5wt%）/La2O3. The results presented in this paper indicate that Ir/La2O3 can be used as a promising catalyst for hydrogen production via ATRE reaction from renewable ethanol.展开更多
The effects of Ce-ZrOx, Ce-LaOx, Ce-SmOx and Ce-GdOx additions to Rh/Al2O3 catalysts on methane autothermal re-forming were investigated. Activity tests showed that the addition of Ce-ZrOx could significantly reduce t...The effects of Ce-ZrOx, Ce-LaOx, Ce-SmOx and Ce-GdOx additions to Rh/Al2O3 catalysts on methane autothermal re-forming were investigated. Activity tests showed that the addition of Ce-ZrOx could significantly reduce the concentration of CO in reformats. When Ce/Zr atomic ratio was 1：1, C%.5Zr0.5O2 solid solution with high thermal stability was obtained, which could effec- tively improve the catalytic performance effectively. The additives of alkaline-earth metals （Mg, K and Ca） on the catalytic properties were also studied. The results of experiments showed that the addition of MgO to Rh/Ce0.5Zr0.5O2/Al2O3 improved the stable per- formance and the carbon resistance of the catalyst. The optimized catalyst was 0.1%Rh/2.0%MgO/40%Ce0.5Zr0.5O2/Al2O3, which showed a highly stable performance for methane autothermal reforming.展开更多
Autothermal steam reforming （ATR） of bio-oil, which couples the endothermic steam reform- ing reaction with the exothermic partial oxidation, offers many advantages from a technical and economic point of view. Effec...Autothermal steam reforming （ATR） of bio-oil, which couples the endothermic steam reform- ing reaction with the exothermic partial oxidation, offers many advantages from a technical and economic point of view. Effective production of hydrogen through ATR of bio-oil was performed at lower temperature with NiCuZnAl catalyst. The highest hydrogen yield from bio-oil reached 64.3% with a nearly complete bio-oil conversion at 600℃, the ratio of steam to carbon fed （S/C） of 3 and the oxygen to carbon ratio （O/C） of 0.34. The reaction conditions in ATR including temperature, O/C, S/C and weight hourly space velocity can be used to control both hydrogen yield and products distribution. The comparison between the ATR and common steam reforming of bio-oil was studied. The mechanism of the ATR of bio-oil was also discussed.展开更多
The catalysts Ni/Al2O3, Ni/ZrO2-CeO2-Al2O3 and Ni/CuO-ZrO2-CeO2-Al2O3 were prepared by the co-precipitation method at a pH of 9 using Na2CO3 as the precipitant. The Ni loading(mass fraction) of the catalysts was 10%. ...The catalysts Ni/Al2O3, Ni/ZrO2-CeO2-Al2O3 and Ni/CuO-ZrO2-CeO2-Al2O3 were prepared by the co-precipitation method at a pH of 9 using Na2CO3 as the precipitant. The Ni loading(mass fraction) of the catalysts was 10%. The ignition process on the catalysts for the autothermal reforming of methane to hydrogen was investigated and the surface properties of the catalysts were characterized by XPS. The results showed that the Ni/Al2O3 catalyst could not ignite the process of autothermal reforming of methane to hydrogen. However, the Ni/CuO-ZrO2-CeO2-Al2O3 catalyst could ignite the process of autothermal reforming of methane to hydrogen at lower reaction temperature(650 ℃) with the conversion of methane reaching 76%. The result of XPS analysis indicated that the promoters could change the binding energy(BE) of Ni2p3/2 obviously. The species of Cu in the Ni/CuO-ZrO2-CeO2-Al2O3 catalyst comprised Cu2 O and Cu2+. The formation of ZrO2-CeO2 solid solution and a large amount of Cu2 O might be the reason leading to good oxygen storage capacity and mobility of lattice oxygen of the Ni/CuO-ZrO2-CeO2-Al2O3 catalyst, which could ignite the process of autothermal reforming of methane to hydrogen at lower reaction temperature.展开更多
This study focused on measurement of the autothermal reforming of biogas over a Ni based monolithic catalyst. The effects of the steam/CH4 （S/C） ratio, O2/CH4 （O2/C） ratio and temperature were investigated. The CH...This study focused on measurement of the autothermal reforming of biogas over a Ni based monolithic catalyst. The effects of the steam/CH4 （S/C） ratio, O2/CH4 （O2/C） ratio and temperature were investigated. The CH4 conversions were higher under all examined temperatures than the equilibrium conversion calculated using the blank outlet temperature, because the catalyst layer was heated by the exothermic catalytic partial oxidation reaction. The CH 4conversion increased with increasing O2/C ratio. Moreover, the CH4 conversion was higher than the equilibrium conversion calculated using the blank outlet temperature for O2/C〉0.42 and reached about 100% at O2/C=0.55. However, the hydrogen concentration decreased for O2/C〉0.45 because hydrogen was combusted to steam in the presence of excess oxygen. On the other hand, the hydrogen and CO2 concentrations increased and the CO concentration decreased with increasing SIC ratio. As a result, it was found that the highest hydrogen concentrations and CH4 conversions were attained at the O2/C ratios of 0.45-0.55 and the SIC ratios of 1.5-2.5. Moreover, the H2/CO ratio could also be controlled in the range from about 2 to 3.5 to give at least 90% CH4 conversion, by regulating the O2/C or S/C ratios.展开更多
NaBH4 sodalites were obtained by two new modified methods of crystallization: (1) autothermal synthesis and (2) crystallization with crossover from gel to melt flow in NaOH flux. Syntheses results were presented accor...NaBH4 sodalites were obtained by two new modified methods of crystallization: (1) autothermal synthesis and (2) crystallization with crossover from gel to melt flow in NaOH flux. Syntheses results were presented according to XRD, SEM and FTIR. Besides important features of both synthesis procedures product properties like crystal size and morphology were investigated. Spherical agglomerates of microcrystalline sodalite of composition Na7[AlSiO4]6BH4(H2O)2 were already observed after 4 h without any external heating by the autothermal procedure. Sodalites of the same average composition but in form of agglomerated nanoparticles are crystallized after very short times (2 h 30’) by the crossover reaction from gel to melt flow. Hydrogen release by heating was further studied for two selected samples with comparable composition from each synthesis procedure. Total hydrogen release by hydrolysis reaction with the internal cage water was found during heating of the autothermal product in synthetic air up to 550°C. In contrast hydrogen release from the nanocrystalline sample of crossover synthesis was not completed when heated under the same conditions. These differences were discussed in terms of crystal size and an earlier loss of the internal water from the nanocrystals of the crossover展开更多
<span style="font-family:Verdana;">A unique laboratory scale auto-thermal moving bed gasifier was designed for studyin</span><span style="font-family:Verdana;">g the thermochemica...<span style="font-family:Verdana;">A unique laboratory scale auto-thermal moving bed gasifier was designed for studyin</span><span style="font-family:Verdana;">g the thermochemical conversion of coal-biomass blends. </span><span style="font-family:Verdana;">For th</span><span style="font-family:Verdana;">is purpose, two coals (lignite and sub-bituminous), two biomass materials (corn stover and switchgrass)</span><span style="font-family:Verdana;">,</span><span style="font-family:Verdana;"> and their respective blends were used. Gasification characteristics of the fuels were evaluated with an emphasis on improving the producer gas composition. The efficiency and product gas compositions reveal that utilizing </span><span style="font-family:Verdana;">the</span><span style="font-family:Verdana;"> inner stainless-steel tubing better promotes heat transfer upwards in the axial direction when compared to utilizing quartz insulation. The H<sub>2</sub>/CO ratio at </span><span style="font-family:Verdana;">the </span><span style="font-family:Verdana;">same operating conditions is much higher due to the increase in bed temperature and heat transfer upwards in the axial direction. This improved the overall efficiency by at least 20%. Using pure oxygen and steam, efficiency greater than 50% was obtained for blends with corn stover at steam to oxygen ratio of 2:1. Also, using air as the gasifying agent greatly improved the H<sub>2</sub>/CO ratios and overall efficiency in blends with corn stover. In contrast, blends with switchgrass were not very effective with respect to the overall gasification characteristics. Blending switchgrass with coal may not be viable option from the viewpoint of generating high quality producer gas for downstream operations.</span>展开更多
This paper explored the feasibility and benefit of CO2 utilization as gasifying agent in the autothermal gasification process. The effects of CO2 injection on reaction temperature and producer gas composition were exa...This paper explored the feasibility and benefit of CO2 utilization as gasifying agent in the autothermal gasification process. The effects of CO2 injection on reaction temperature and producer gas composition were examined in a pilot scale downdraft gasifier by varying the CO2/C ratio from 0.6 to 1.6. O2 was injected at an equivalence ratio of approximately 0.33-0.38 for supply- ing heat through partial combustion. The results were also compared with those of air gasification. In general, the increase in CO2 injection resulted in the shift of combustion zone to the downstream of the gasifier. However, compared with that of air gasification, the long and distributed high temperature zones were obtained in CO2-O2 gasification with a CO2/C ratio of 0.6-1.2. The progress of the expected CO2 to CO conversion can be implied from the relatively insignificant decrease in CO fraction as the CO2/C ratio increased. The producer gas heating value of CO2-O2 gasification was consistently higher than that of air gasification. These results show the potential of CO2-O2 gasification for producing high qualityproducer gas in an efficient manner, and the necessity for more work to deeply imply the observation.展开更多
Currently,CO_(2) conversion and utilization have become a key to mitigate the global warming.In this study,a novel separate-type autothermal dry reforming of methane(S-ATDRM)system is proposed and simulated,in which t...Currently,CO_(2) conversion and utilization have become a key to mitigate the global warming.In this study,a novel separate-type autothermal dry reforming of methane(S-ATDRM)system is proposed and simulated,in which the methane dry reforming combined with methane partial oxidation is performed in a circulating fluidized bed with exergy recuperation to eliminate the negative effect of the products of CH_(4) partial oxidation on the DRM reaction and further improve the CO_(2) conversion efficiency.The results demonstrate that this S-ATDRM system can achieve an exergy efficiency of 84.7%,and about 1055.7 kW of exergy can be recuperated from the process for crude syngas cooling and reapplied for pre-heating of feedstocks of CO_(2),O2 and CH_(4).It is found that the largest exergy destruction in this system occurs in the partial oxidation reactor,which occupies ca.45.6%of the whole exergy loss.Comparing with the conventional ATDRM system,although the exergy of S-ATDRM system is decreased by approximately 0.3%,the CO_(2) conversion is substantially increased by about 11.3%.展开更多
Partial oxidation gasification in supercritical water could produce fuel gases(such as H2, CO and CH4) and significantly reduce the energy consumption. In this work, an energetic model was developed to analyze the par...Partial oxidation gasification in supercritical water could produce fuel gases(such as H2, CO and CH4) and significantly reduce the energy consumption. In this work, an energetic model was developed to analyze the partial oxidative gasification of biomass(glucose and lignin) in supercritical water and the related key factors on which gasification under autothermal condition depended upon. The results indicated that the oxidant equivalent ratio(ER) should be over 0.3 as the concern about energy balance but less than 0.6 as the concern about fuel gas production. Feedstocks such as glucose and lignin also had different energy recovery efficiency. For materials which can be efficiently gasified, the partial oxidation might be a way for energy based on the combustion of fuel gases. Aromatic materials such as lignin and coal are more potential since partial oxidation could produce similar amount of fuel gases as direct gasification and offer additional energy. Energy recovered pays a key role to achieve an autothermal process. Keeping heat exchanger efficiency above 80% and heat transfer coefficient below15 k J·s-1is necessary to maintain the autothermal status. The results also indicated that the biomass loading should be above 15% but under 20% for an autothermal gasification, since the increase of biomass loading could improve the energy supplied but decrease the efficiency of gasification and gaseous yields. In general,some specific conditions exist among different materials.展开更多
A mathematical model for the catalytic autothermal reforming(ATR)reaction of synthetic crude glycerol to hydrogen in a fixed bed tubular reactor(FBTR)and over an in-house developed metal oxide catalyst is presented in...A mathematical model for the catalytic autothermal reforming(ATR)reaction of synthetic crude glycerol to hydrogen in a fixed bed tubular reactor(FBTR)and over an in-house developed metal oxide catalyst is presented in this work.The heterogeneous model equations account for a two-phase system of solid catalyst and bulk feed gas.Also,the ATR of crude glycerol reaction scheme and intrinsic kinetic rate model over an active,selective,and stable nickel-based catalyst were integrated in the developed model.Also,the model was validated using experimental data generated in our labs for the ATR of synthetic crude glycerol.The modelling results adequately described the detailed gas product composition and distribution,temperature profiles,and conversion propagation in the axial direction of the fixed bed reactor over a wide range of reaction temperature(773–923 K)and mass-time(12.71–158.23 g cat·min·(mol C)^(-1)).The crude glycerol conversion predicted with the model showing a close resemblance to those obtained experimentally with an average absolute deviation(AAD)of less than 8%.The maximum crude glycerol conversion and hydrogen yield were found to be 92%and 3 mol hydrogen/mol crude glycerol,respectively.Also,the gas product concentration profile in the reactor was adequately described(90%)accuracy with a hydrogen concentration of 39%(volume).展开更多
The effects of CO2 on the partial oxidation of heptane for hydrogen generation have been studied. Based on the experimental results and thermodynamic equilibrium calculations, the validity of CO2 addition to weaken t...The effects of CO2 on the partial oxidation of heptane for hydrogen generation have been studied. Based on the experimental results and thermodynamic equilibrium calculations, the validity of CO2 addition to weaken the hot spots, and the feasibility of the autothermal operation are discussed.展开更多
文摘Ni-Cu/ZrO2-CeO2-Al2O3 catalysts were prepared by co-precipitation method at pH=9 and using Na2CO3 as the precipitant. The Ni loading （mass fraction） of the catalysts was 10%. The catalysts were characterized by X-ray diffraction, temperature-programmed oxidation （TPO）, scanning electron microscope （SEM）, and X-ray photoelectron spectroscopy （XPS）. The effects of calcined temperature of support on coke deposition were studied. TPO, SEM and XPS results indicated there was no peak of higher temperature oxygen consumption on Ni-Cu/ZrO2-CeO2-Al2O3 catalyst （support was calcined at 800 ℃）, which could lead to the deactivation of the catalyst. The carbon species were carbonate and inactive carbon （filamentous carbon species） on the surface of catalyst reacting for 40 h which perhaps led to the deactivation of the catalyst.
基金The project is supported by Guangdong Provincial Natural Science Foundation of China(030514)Science and Technology Plan of Guangdong Province(2004B33401006)
文摘Ni catalysts supported on various mixed oxides of Al2O3 with rare earth oxide and transitional metal oxides were synthesized. The studies focused on the measurement of the autothermal reforming of methane to hydrogen over Ni catalysts supported on the mixed oxide ZrxCe30-xAl70Oδ （x-=5, 10, 15）. The catalytic performance of Ni/Zr10Ce20Al70Oδ was better than that of other catalysts. XRD results showed that the addition of Zr to Ni/Ce30Al70Oδ prevented the formation of NiAl2O4 and facilitated the dispersion of NiO. Effects of CuO addition to Zr10Ce20Al70Oδ were also investigated. The activity of Ni catalyst supported on CuO-ZrO2-CeO2-Al2O3 was somewhat affected and the Ni/Cu5Zr10Ce20Al65Oδ showed the best catalytic performance with the highest CH4 conversion, yield of H2, selectivity for H2 and H2/CO production ratio in operation temperatures ranging from 650 to 750 ℃.
基金This work was supported by Guangdong Natural Science Foundation of China (030514)Science and Technology Programs of Guangdong Province of China (2004B33401006)
文摘The transition metals （Cu, Co, and Fe） were applied to modify Ni/Ce0.2Zr0.1Al0.7Oδ catalyst. The effects of transition metals on the catalytic properties of Ni/Ce0.2Zr0.1Al0.7Oδ autothermal reforming of methane were investigated. The Ni-supported catalysts were characterized by XRD, TPR and XPS. Tests in autothermal reforming of methane to hydrogen showed that the addition of transition metals （Cu and Co） significantly increased the activity of catalyst under the conditions of lower reaction temperature, and Ni/Cu0.05Ce0.2Zr0.1Al0.65Oδ was found to have the highest conversion of CH4 among all catalysts in the operation temperatures ranging from 923 K to 1023 K. TPR, XRD and XPS measurements indicated that the cubic phases of CexZr1-xO2 solid solution were formed in the preparation process of catalysts. Strong interaction was found to exist between NiO and CexZr1-xO2 solid solution. The addition of Cu improved the dispersion of NiO, inhibited the formation of NiAl2O4, and thus significantly promoted the activity of the catalyst Ni/Cu0.05Ce0.2Zr0.1Al0.65Oδ
基金supported by Guangdong Provincial Natural Science Foundation of China(030514)Science and Technology Plan of Guangdong Province of China(2004B33401006)Doctoral Startup Foundation of Guang Dong Pharmaceutical University.
文摘Ni catalysts supported on Al2O3, ZrO2-Al2O3, CeO2-Al2O3 and ZrO2-CeO2-Al2O3 were prepared by coprecipitation method, and their catalytic performances for autothermal reforming of methane to hydrogen were investigated. The Ni-supported catalysts were characterized by XRD, TPR and XPS. The relationship between the structures and catalytic activities of the catalysts was discussed. The results showed that the catalytic activity and stability of the Ni/ZrO2-CeO2-Al2O3 catalyst was better than those of other catalysts with the highest CH4 conversion, H2/CO and H2/COx ratio at 750 ℃. The catalyst showed a little deactivation along the reaction time during its 72 h on stream with the mean deactivation rate of 0.08%/h. The catalytic performance of the Ni/ZrO2-CeO2-Al2O3 catalyst was also affected by reaction temperature, no2 ： nCH4 molar ratio and nH2O ： nCH4 molar ratio. TPR, XRD and XPS measurements indicated that the formation of ZrO2-CeO2 solid solution could improve the dispersion of NiO, and inhibit the formation of NiAl2O3, and thus significantly promoted the catalytic activity of the Ni/ZrO2-CeO2-Al2O3 catalyst.
基金supported by the Natural Science Foundation of Guangdong Province(030514)the Science and Technology Plan of Guangdong Province(2004B33401006).
文摘The effect of promoter Ce on the catalytic performance of Ni/Al2O3 catalyst for autothermal reforming of methane to hydrogen was investigated. The catalysts were characterized by X-ray diffraction （XRD）, temperature-programmed reduction （TPR）, and X-ray photoelectron spectroscopy （XPS）. The results indicated that the catalytic performance of the catalysts was improved with the addition of Ce. Ni/Ce30Al70Oδ showed the highest CH4 conversion in operation temperatures ranging from 650 ℃ to 850 ℃. At the same time, the decrease in H2/CO ratio with increasing reaction temperature was consistent with the fact that water-gas shift reaction was thermodynamically unfavorable at higher temperatures. The XRD result indicated that adding Ce to Ni/Al2O3 catalyst prevented the formation of NiAl2O4 and facilitated the formation of NiO. The formation of NiO increased the number of active sites, resulting in higher activity. Comparing the TPR profiles of Ni/Ce30Al70Oδ with Ni/Al2O3, it could be clearly observed that with the addition of Ce, the total reduction peak areas in the middle and low temperatures increased. It was most probably that the addition of Ce inhibited the stronger interaction between Ni and Al2O3 to form the phase of NiAl2O4, and favored the formation of the strong interaction between NiO species and CeO2. Therefore, the addition of Ce to the Ni/Al2O3 catalyst increased the active surface that promoted the activity of the catalyst.
基金Supported by the National 973 Program of China on Hydrogen Energy (TG2000026410) and International Cooperation Projecton Hydrogen Energy (2001AA515080).
文摘Autothermal reforming (ATR) is one of the leading methods for hydrogen production from hydrocar- bons. Liquefied petroleum gas, with propane as the main component, is a promising fuel for on-board hydrogen producing systems in fuel cell vehicles and for domestic fuel cell power generation devices. In this article, propane ATR process is studied and operation conditions are optimized with PRO/Ⅱ? from SIMSCI for proton exchange membrane fuel cell application. In the ATR system including water gas shift and preferential oxidation, heat in the hot streams and cold streams is controlled to be in balance. Different operation conditions are studied and drawn in contour plots. The region for ATR reforming with the highest efficiency can thus be identified. One operation point was chosen with the following process parameters: feed temperature for the ATR reactor is 425℃, steam to carbon ratio S/C is 2.08, air stoichiometry is 0.256. Thermal efficiency for the integrated system is calculated to be as high as 84.0 % with 38.27 % H2 and 3.2μl·L-1 CO in the product gas.
基金Supported by the Doctoral Foundation of Northeast Dianli University (BSJXM-200814)Foundations of Bureau of Jilin Province (2008424)
文摘Biodegradation parameters and kinetic characteristics for pre-treating waste strains of Klebsiella pneu-moniae were studied in laboratory scale with an insulated reactor by an innovative technique,autothermal thermo-philic aerobic digestion(ATAD) . Based on an Arrhenius-type equation,an empirical model was developed to corre-late the removal of total suspended solid(TSS) with the initial TSS concentration,influent reaction temperature,aeration rate and stirring rate. The reaction temperatures of the ATAD system could be raised from the ambient temperatures of 25 °C to a maximum temperature of 65 °C. The exponentials for the initial TSS concentration,aeration rate and stirring rate were 1.579,-0.8175 and-0.6549,respectively,and the apparent activation energy was 6.8774 kJ·mol-1. The correlation coefficient for the pre-exponential factor was 0.9223. The TSS removal effi-ciency predicted by the model was validated with an actual test,showing a maximum relative deviation of 10.79%. The new model has a good practicability.
基金supported by the National Natural Science Foundation of China (No. 50675070)
文摘Hydrogen was produced over noble metal（Ir, Ru, Rh, Pd） catalysts supported on various oxides, including γ-Al2O3, CeO2, ZrO2 and La2O3, via the autothermal reforming reaction of ethanol （ATRE） and oxidative reforming reaction of ethanol （OSRE）. The conversion of ethanol and selectivites for hydrogen and byproducts such as methane, ethylene and acetaldehyde were studied. It was found that lanthana alone possessed considerable activity for the ATRE reaction, which could be used as a functional support for ATRE catalysts. It was demonstrated that Ir/La2O3 prevented the formation of methane, and Rh/La2O3 encumbered the production of ethylene and acetaldehyde. ATRE reaction was carried out over La2O3-supported catalysts （Ir/La2O3） with good stability on stream, high conversion, and excellent hydrogen selectivity approaching thermodynamic limit under autothermal condition. Typically, 3.4H2 molecules can be extracted from a pair of ethanol and water molecules over Ir（5wt%）/La2O3. The results presented in this paper indicate that Ir/La2O3 can be used as a promising catalyst for hydrogen production via ATRE reaction from renewable ethanol.
基金supported by National Natural Science Foundation of China(21076206,21376237)National Key Foundational Research Project(973) of China(2010CB732302)National High Technology Research and Development Program(863) of China(2011AA050706)
文摘The effects of Ce-ZrOx, Ce-LaOx, Ce-SmOx and Ce-GdOx additions to Rh/Al2O3 catalysts on methane autothermal re-forming were investigated. Activity tests showed that the addition of Ce-ZrOx could significantly reduce the concentration of CO in reformats. When Ce/Zr atomic ratio was 1：1, C%.5Zr0.5O2 solid solution with high thermal stability was obtained, which could effec- tively improve the catalytic performance effectively. The additives of alkaline-earth metals （Mg, K and Ca） on the catalytic properties were also studied. The results of experiments showed that the addition of MgO to Rh/Ce0.5Zr0.5O2/Al2O3 improved the stable per- formance and the carbon resistance of the catalyst. The optimized catalyst was 0.1%Rh/2.0%MgO/40%Ce0.5Zr0.5O2/Al2O3, which showed a highly stable performance for methane autothermal reforming.
文摘Autothermal steam reforming （ATR） of bio-oil, which couples the endothermic steam reform- ing reaction with the exothermic partial oxidation, offers many advantages from a technical and economic point of view. Effective production of hydrogen through ATR of bio-oil was performed at lower temperature with NiCuZnAl catalyst. The highest hydrogen yield from bio-oil reached 64.3% with a nearly complete bio-oil conversion at 600℃, the ratio of steam to carbon fed （S/C） of 3 and the oxygen to carbon ratio （O/C） of 0.34. The reaction conditions in ATR including temperature, O/C, S/C and weight hourly space velocity can be used to control both hydrogen yield and products distribution. The comparison between the ATR and common steam reforming of bio-oil was studied. The mechanism of the ATR of bio-oil was also discussed.
基金supported by the Guangdong Provincial Natural Science Foundation (030514)the Science and Technology Plan of Guangdong Province of China (2004B33401006)the Doctoral Startup Foundation of Guangdong Pharmaceutical University
文摘The catalysts Ni/Al2O3, Ni/ZrO2-CeO2-Al2O3 and Ni/CuO-ZrO2-CeO2-Al2O3 were prepared by the co-precipitation method at a pH of 9 using Na2CO3 as the precipitant. The Ni loading(mass fraction) of the catalysts was 10%. The ignition process on the catalysts for the autothermal reforming of methane to hydrogen was investigated and the surface properties of the catalysts were characterized by XPS. The results showed that the Ni/Al2O3 catalyst could not ignite the process of autothermal reforming of methane to hydrogen. However, the Ni/CuO-ZrO2-CeO2-Al2O3 catalyst could ignite the process of autothermal reforming of methane to hydrogen at lower reaction temperature(650 ℃) with the conversion of methane reaching 76%. The result of XPS analysis indicated that the promoters could change the binding energy(BE) of Ni2p3/2 obviously. The species of Cu in the Ni/CuO-ZrO2-CeO2-Al2O3 catalyst comprised Cu2 O and Cu2+. The formation of ZrO2-CeO2 solid solution and a large amount of Cu2 O might be the reason leading to good oxygen storage capacity and mobility of lattice oxygen of the Ni/CuO-ZrO2-CeO2-Al2O3 catalyst, which could ignite the process of autothermal reforming of methane to hydrogen at lower reaction temperature.
基金supported by the greenhouse gas mitigation technology development program"Technology Developments on Hydrogen Production from Biomass and Waste"organized by the National Institute for Environmental Studies(NIES)for 2002~2008 in trust from the Ministry of the Environment(MOE)
文摘This study focused on measurement of the autothermal reforming of biogas over a Ni based monolithic catalyst. The effects of the steam/CH4 （S/C） ratio, O2/CH4 （O2/C） ratio and temperature were investigated. The CH4 conversions were higher under all examined temperatures than the equilibrium conversion calculated using the blank outlet temperature, because the catalyst layer was heated by the exothermic catalytic partial oxidation reaction. The CH 4conversion increased with increasing O2/C ratio. Moreover, the CH4 conversion was higher than the equilibrium conversion calculated using the blank outlet temperature for O2/C〉0.42 and reached about 100% at O2/C=0.55. However, the hydrogen concentration decreased for O2/C〉0.45 because hydrogen was combusted to steam in the presence of excess oxygen. On the other hand, the hydrogen and CO2 concentrations increased and the CO concentration decreased with increasing SIC ratio. As a result, it was found that the highest hydrogen concentrations and CH4 conversions were attained at the O2/C ratios of 0.45-0.55 and the SIC ratios of 1.5-2.5. Moreover, the H2/CO ratio could also be controlled in the range from about 2 to 3.5 to give at least 90% CH4 conversion, by regulating the O2/C or S/C ratios.
文摘NaBH4 sodalites were obtained by two new modified methods of crystallization: (1) autothermal synthesis and (2) crystallization with crossover from gel to melt flow in NaOH flux. Syntheses results were presented according to XRD, SEM and FTIR. Besides important features of both synthesis procedures product properties like crystal size and morphology were investigated. Spherical agglomerates of microcrystalline sodalite of composition Na7[AlSiO4]6BH4(H2O)2 were already observed after 4 h without any external heating by the autothermal procedure. Sodalites of the same average composition but in form of agglomerated nanoparticles are crystallized after very short times (2 h 30’) by the crossover reaction from gel to melt flow. Hydrogen release by heating was further studied for two selected samples with comparable composition from each synthesis procedure. Total hydrogen release by hydrolysis reaction with the internal cage water was found during heating of the autothermal product in synthetic air up to 550°C. In contrast hydrogen release from the nanocrystalline sample of crossover synthesis was not completed when heated under the same conditions. These differences were discussed in terms of crystal size and an earlier loss of the internal water from the nanocrystals of the crossover
文摘<span style="font-family:Verdana;">A unique laboratory scale auto-thermal moving bed gasifier was designed for studyin</span><span style="font-family:Verdana;">g the thermochemical conversion of coal-biomass blends. </span><span style="font-family:Verdana;">For th</span><span style="font-family:Verdana;">is purpose, two coals (lignite and sub-bituminous), two biomass materials (corn stover and switchgrass)</span><span style="font-family:Verdana;">,</span><span style="font-family:Verdana;"> and their respective blends were used. Gasification characteristics of the fuels were evaluated with an emphasis on improving the producer gas composition. The efficiency and product gas compositions reveal that utilizing </span><span style="font-family:Verdana;">the</span><span style="font-family:Verdana;"> inner stainless-steel tubing better promotes heat transfer upwards in the axial direction when compared to utilizing quartz insulation. The H<sub>2</sub>/CO ratio at </span><span style="font-family:Verdana;">the </span><span style="font-family:Verdana;">same operating conditions is much higher due to the increase in bed temperature and heat transfer upwards in the axial direction. This improved the overall efficiency by at least 20%. Using pure oxygen and steam, efficiency greater than 50% was obtained for blends with corn stover at steam to oxygen ratio of 2:1. Also, using air as the gasifying agent greatly improved the H<sub>2</sub>/CO ratios and overall efficiency in blends with corn stover. In contrast, blends with switchgrass were not very effective with respect to the overall gasification characteristics. Blending switchgrass with coal may not be viable option from the viewpoint of generating high quality producer gas for downstream operations.</span>
基金This work was supported by the National Natural Science Foundation of China （Grant No. 51406182） and Talented Young Scientists Program （No. INA-14-003）.
文摘This paper explored the feasibility and benefit of CO2 utilization as gasifying agent in the autothermal gasification process. The effects of CO2 injection on reaction temperature and producer gas composition were examined in a pilot scale downdraft gasifier by varying the CO2/C ratio from 0.6 to 1.6. O2 was injected at an equivalence ratio of approximately 0.33-0.38 for supply- ing heat through partial combustion. The results were also compared with those of air gasification. In general, the increase in CO2 injection resulted in the shift of combustion zone to the downstream of the gasifier. However, compared with that of air gasification, the long and distributed high temperature zones were obtained in CO2-O2 gasification with a CO2/C ratio of 0.6-1.2. The progress of the expected CO2 to CO conversion can be implied from the relatively insignificant decrease in CO fraction as the CO2/C ratio increased. The producer gas heating value of CO2-O2 gasification was consistently higher than that of air gasification. These results show the potential of CO2-O2 gasification for producing high qualityproducer gas in an efficient manner, and the necessity for more work to deeply imply the observation.
基金JST Grant Number JPMJPF2104,Japan,and the National Natural Science Foundation of China(No.U1710101),P.R.China.Z.Zhao gratefully acknowledges China Scholarship Council(CSC)Y.Situmorang gratefully acknowledges the scholarship from Ministry of Education,Culture,Sport,Science and Technology(MEXT)of Japan.
文摘Currently,CO_(2) conversion and utilization have become a key to mitigate the global warming.In this study,a novel separate-type autothermal dry reforming of methane(S-ATDRM)system is proposed and simulated,in which the methane dry reforming combined with methane partial oxidation is performed in a circulating fluidized bed with exergy recuperation to eliminate the negative effect of the products of CH_(4) partial oxidation on the DRM reaction and further improve the CO_(2) conversion efficiency.The results demonstrate that this S-ATDRM system can achieve an exergy efficiency of 84.7%,and about 1055.7 kW of exergy can be recuperated from the process for crude syngas cooling and reapplied for pre-heating of feedstocks of CO_(2),O2 and CH_(4).It is found that the largest exergy destruction in this system occurs in the partial oxidation reactor,which occupies ca.45.6%of the whole exergy loss.Comparing with the conventional ATDRM system,although the exergy of S-ATDRM system is decreased by approximately 0.3%,the CO_(2) conversion is substantially increased by about 11.3%.
基金Supported by the National Natural Science Foundation of China(21037001,21076091,21307049)the National Key Project for Basic Research of China(2008BAC32B06-1)+2 种基金Yunnan Province High-tech Talent Introduction Project(2010CI110)the Important Yunnan Province's Science&Technology Specific Project(2012ZB002)the Yunnan Science Foundation(2013FZ032,14118583)
文摘Partial oxidation gasification in supercritical water could produce fuel gases(such as H2, CO and CH4) and significantly reduce the energy consumption. In this work, an energetic model was developed to analyze the partial oxidative gasification of biomass(glucose and lignin) in supercritical water and the related key factors on which gasification under autothermal condition depended upon. The results indicated that the oxidant equivalent ratio(ER) should be over 0.3 as the concern about energy balance but less than 0.6 as the concern about fuel gas production. Feedstocks such as glucose and lignin also had different energy recovery efficiency. For materials which can be efficiently gasified, the partial oxidation might be a way for energy based on the combustion of fuel gases. Aromatic materials such as lignin and coal are more potential since partial oxidation could produce similar amount of fuel gases as direct gasification and offer additional energy. Energy recovered pays a key role to achieve an autothermal process. Keeping heat exchanger efficiency above 80% and heat transfer coefficient below15 k J·s-1is necessary to maintain the autothermal status. The results also indicated that the biomass loading should be above 15% but under 20% for an autothermal gasification, since the increase of biomass loading could improve the energy supplied but decrease the efficiency of gasification and gaseous yields. In general,some specific conditions exist among different materials.
基金the financial support provided by the Natural Science and Engineering Research Council of Canada (NSERC)the Canada Foundation for Innovation (CFI)
文摘A mathematical model for the catalytic autothermal reforming(ATR)reaction of synthetic crude glycerol to hydrogen in a fixed bed tubular reactor(FBTR)and over an in-house developed metal oxide catalyst is presented in this work.The heterogeneous model equations account for a two-phase system of solid catalyst and bulk feed gas.Also,the ATR of crude glycerol reaction scheme and intrinsic kinetic rate model over an active,selective,and stable nickel-based catalyst were integrated in the developed model.Also,the model was validated using experimental data generated in our labs for the ATR of synthetic crude glycerol.The modelling results adequately described the detailed gas product composition and distribution,temperature profiles,and conversion propagation in the axial direction of the fixed bed reactor over a wide range of reaction temperature(773–923 K)and mass-time(12.71–158.23 g cat·min·(mol C)^(-1)).The crude glycerol conversion predicted with the model showing a close resemblance to those obtained experimentally with an average absolute deviation(AAD)of less than 8%.The maximum crude glycerol conversion and hydrogen yield were found to be 92%and 3 mol hydrogen/mol crude glycerol,respectively.Also,the gas product concentration profile in the reactor was adequately described(90%)accuracy with a hydrogen concentration of 39%(volume).
文摘The effects of CO2 on the partial oxidation of heptane for hydrogen generation have been studied. Based on the experimental results and thermodynamic equilibrium calculations, the validity of CO2 addition to weaken the hot spots, and the feasibility of the autothermal operation are discussed.
