Studies on ultrafine particle catalyst have attracted many researchers' attention by its large surface area,higher activity and selectivity.Based on the mechanism of α-Fe and Fe_xC_y as the catalytical active spe...Studies on ultrafine particle catalyst have attracted many researchers' attention by its large surface area,higher activity and selectivity.Based on the mechanism of α-Fe and Fe_xC_y as the catalytical active species this paper reports for the first time the preparation method of Fe_3C ultrafine parti- cle catalyst,from highly dispersed amorphous Fe powder and free carbon.The Fe powder and free car- bon,prepared by laser pyrolysis technique,was then treated by washing and heating at high tempera- ture protected with N_2.The catalyst prepared under different experimental conditions was characterazed by means of XRD,electronic diffraction and TEM.It shows that the crystlline grain size is in a range of 1-4nm and composed of Fe_3C and α-Fe.It has been found that the ultrafine particle iron-carbonide catalyst exhibited much higher activity and selectivity to light olefins.At the standard atmosphere and 380℃ reaction temperature,the conversion of CO reached a maximum of 80%.展开更多
The gasification industries make use of biomass residue as feedstock to produce synthesis gas,but the gasification of this waste biomass generates tons of ash everyday.Performance properties and agglomeration behavior...The gasification industries make use of biomass residue as feedstock to produce synthesis gas,but the gasification of this waste biomass generates tons of ash everyday.Performance properties and agglomeration behavior of corncob ash(CCA) collected from the gasification of corncobs in a pilot-scale gasification station were investigated by using some experimental methods.Based on the chemical composition results,the agglomeration tendency of CCA from combustion and gasification process was also analyzed.Chemical analysis shows that the fly ash is mainly composed of inorganic matters formed by K,Mg,Ca,Na,Fe,Al,S,etc.The agglomeration characteristics indicate that the slagging degree increases with the increase of ashing temperature,and the slagging tendency of these CCA samples from gasification or combustion is different with various slagging indices.All CCA samples from combustion or gasification can cause slagging/fouling problems in thermal conversion systems.The applications of CCA are closely related to its performances,and CCA has the potential to be used in various fields,for example,as a material for ceramic products and activated carbon,as an adsorbent,as a crude fertilizer,and as a structural material.展开更多
A series of x （Fe,Ni）/Al2O3 catalysts （x = 2-12 wt%） were prepared using incipient wetness method and studied for the conversion of synthesis gas to light olefins.6 wt%（Fe,Ni）/Al2O3 catalyst was found to be the ...A series of x （Fe,Ni）/Al2O3 catalysts （x = 2-12 wt%） were prepared using incipient wetness method and studied for the conversion of synthesis gas to light olefins.6 wt%（Fe,Ni）/Al2O3 catalyst was found to be the optimal catalyst for the production of C2-C4 olefins.The effects of calcination behaviors and operational conditions on the catalytic performance of the optimal catalyst were investigated.The best operational conditions were molar feed ratio H2/CO = 2/1,T = 260 ℃,gas hourly space velocity （GHSV） = 2600 h^-1 and the pressure of 3 bar.Character-izations of both precursors and catalysts were carried out using X-ray diffraction （XRD）,temperature-programmed reduction （TPR）,scanning electron microscopy （SEM）,N2-adsorption-desorption measurement,thermal gravimetric analysis （TGA） and differential scanning calorimetry （DSC）.展开更多
The three-parameter Petal-Teja equation of state coupled with a characterization proceduref0r C<sub>7+</sub>-fraction based on gamma distribution function was employed to predict the phase behaviorof eight...The three-parameter Petal-Teja equation of state coupled with a characterization proceduref0r C<sub>7+</sub>-fraction based on gamma distribution function was employed to predict the phase behaviorof eight gas condensates.The lumping of the subdivided single carbon number（SCN）hydrocarbons inthe plus-fraction and the choice of empirical correlations for calculating the critical properties andacentric factor of SCN hydrocarbons were discussed.展开更多
By introducing a vibrating force field into the extrusion process of polymer melt, an experimental equipment of constant velocity type dynamic rheometer of capillary (CVDRC) was designed. A set of experimental procedu...By introducing a vibrating force field into the extrusion process of polymer melt, an experimental equipment of constant velocity type dynamic rheometer of capillary (CVDRC) was designed. A set of experimental procedures was established, by which the dynamic rheological parameters of polymer can be acquired, and a set of data management methods to undergo time-domain or frequency-domain analysis was set up for dynamic rheological data of polymer melt. Meantime, the characterization formula of polymer melt's rheological behavior in a vibrating force field was set up. The instantaneous value of capillary entry pressure, capillary volume flow rate and their phase difference were measured and analyzed, and the melt apparent viscosity, which describes the rheological behavior of polymer melt in a vibrating force field, was obtained.展开更多
The stress–strain behavior and strain rate sensitivity of pre-strained Ni80Cr20（Ni20Cr） were studied at strain rates from 4.8×10^（–4）s^（–1） to 1.1×10^（–1）s^（–1）. Specimens were prepared throug...The stress–strain behavior and strain rate sensitivity of pre-strained Ni80Cr20（Ni20Cr） were studied at strain rates from 4.8×10^（–4）s^（–1） to 1.1×10^（–1）s^（–1）. Specimens were prepared through cold drawing with abnormal plastic deformation. The texture of the specimen was characterized using electron backscatter diffraction. Results revealed that the ultimate tensile strength and ductility of the pre-strained Ni20Cr microwires simultaneously increased with increasing strain rate. Twinning-induced negative strain rate sensitivity was discovered. Positive strain rate sensitivity was present in fracture flow stress, whereas negative strain rate sensitivity was detected in flow stress values of σ_（0.5%） and σ_（1%）. Tensile test of the pre-strained Ni20Cr showed that twinning deformation predominated, whereas dislocation slip deformation dominated when twinning deformation reached saturation. The trends observed in the fractions of 2°-5°, 5°-15°, and 15°-180° grain boundaries confirmed that twinning deformation dominated the first stage.展开更多
A novel method for controlled synthesis of crystalline molybdenum dioxides nanowhiskers （whisker-MoO2） by using moderate reductive and precursor ion under hydrothermal conditions is reported. The result shows that t...A novel method for controlled synthesis of crystalline molybdenum dioxides nanowhiskers （whisker-MoO2） by using moderate reductive and precursor ion under hydrothermal conditions is reported. The result shows that the as-obtained samples have a monoclinic structure, and the whisker-MoO2 is composed of nanowires with diameters of ca. 20 nm. Formation of whisker-MoO2 was through a typical precursor-reduction process, in which cetyltrimethylammonium bromide （CTAB） served as a cationic surfactant and acetone as a reductant. The electrochemical behavior of whisker-MoO2 was studied.展开更多
基金The project was supported by the National Natural Science Foundation of China.
文摘Studies on ultrafine particle catalyst have attracted many researchers' attention by its large surface area,higher activity and selectivity.Based on the mechanism of α-Fe and Fe_xC_y as the catalytical active species this paper reports for the first time the preparation method of Fe_3C ultrafine parti- cle catalyst,from highly dispersed amorphous Fe powder and free carbon.The Fe powder and free car- bon,prepared by laser pyrolysis technique,was then treated by washing and heating at high tempera- ture protected with N_2.The catalyst prepared under different experimental conditions was characterazed by means of XRD,electronic diffraction and TEM.It shows that the crystlline grain size is in a range of 1-4nm and composed of Fe_3C and α-Fe.It has been found that the ultrafine particle iron-carbonide catalyst exhibited much higher activity and selectivity to light olefins.At the standard atmosphere and 380℃ reaction temperature,the conversion of CO reached a maximum of 80%.
基金Project(2013020137)supported by the Natural Science Foundation of Liaoning Province,ChinaProject(2015-36)supported by Rural Energy Comprehensive Construction Foundation of the Ministry of Agriculture,China
文摘The gasification industries make use of biomass residue as feedstock to produce synthesis gas,but the gasification of this waste biomass generates tons of ash everyday.Performance properties and agglomeration behavior of corncob ash(CCA) collected from the gasification of corncobs in a pilot-scale gasification station were investigated by using some experimental methods.Based on the chemical composition results,the agglomeration tendency of CCA from combustion and gasification process was also analyzed.Chemical analysis shows that the fly ash is mainly composed of inorganic matters formed by K,Mg,Ca,Na,Fe,Al,S,etc.The agglomeration characteristics indicate that the slagging degree increases with the increase of ashing temperature,and the slagging tendency of these CCA samples from gasification or combustion is different with various slagging indices.All CCA samples from combustion or gasification can cause slagging/fouling problems in thermal conversion systems.The applications of CCA are closely related to its performances,and CCA has the potential to be used in various fields,for example,as a material for ceramic products and activated carbon,as an adsorbent,as a crude fertilizer,and as a structural material.
文摘A series of x （Fe,Ni）/Al2O3 catalysts （x = 2-12 wt%） were prepared using incipient wetness method and studied for the conversion of synthesis gas to light olefins.6 wt%（Fe,Ni）/Al2O3 catalyst was found to be the optimal catalyst for the production of C2-C4 olefins.The effects of calcination behaviors and operational conditions on the catalytic performance of the optimal catalyst were investigated.The best operational conditions were molar feed ratio H2/CO = 2/1,T = 260 ℃,gas hourly space velocity （GHSV） = 2600 h^-1 and the pressure of 3 bar.Character-izations of both precursors and catalysts were carried out using X-ray diffraction （XRD）,temperature-programmed reduction （TPR）,scanning electron microscopy （SEM）,N2-adsorption-desorption measurement,thermal gravimetric analysis （TGA） and differential scanning calorimetry （DSC）.
文摘The three-parameter Petal-Teja equation of state coupled with a characterization proceduref0r C<sub>7+</sub>-fraction based on gamma distribution function was employed to predict the phase behaviorof eight gas condensates.The lumping of the subdivided single carbon number（SCN）hydrocarbons inthe plus-fraction and the choice of empirical correlations for calculating the critical properties andacentric factor of SCN hydrocarbons were discussed.
文摘By introducing a vibrating force field into the extrusion process of polymer melt, an experimental equipment of constant velocity type dynamic rheometer of capillary (CVDRC) was designed. A set of experimental procedures was established, by which the dynamic rheological parameters of polymer can be acquired, and a set of data management methods to undergo time-domain or frequency-domain analysis was set up for dynamic rheological data of polymer melt. Meantime, the characterization formula of polymer melt's rheological behavior in a vibrating force field was set up. The instantaneous value of capillary entry pressure, capillary volume flow rate and their phase difference were measured and analyzed, and the melt apparent viscosity, which describes the rheological behavior of polymer melt in a vibrating force field, was obtained.
基金Funded by the National Natural Science Foundation of China(No.11135007)
文摘The stress–strain behavior and strain rate sensitivity of pre-strained Ni80Cr20（Ni20Cr） were studied at strain rates from 4.8×10^（–4）s^（–1） to 1.1×10^（–1）s^（–1）. Specimens were prepared through cold drawing with abnormal plastic deformation. The texture of the specimen was characterized using electron backscatter diffraction. Results revealed that the ultimate tensile strength and ductility of the pre-strained Ni20Cr microwires simultaneously increased with increasing strain rate. Twinning-induced negative strain rate sensitivity was discovered. Positive strain rate sensitivity was present in fracture flow stress, whereas negative strain rate sensitivity was detected in flow stress values of σ_（0.5%） and σ_（1%）. Tensile test of the pre-strained Ni20Cr showed that twinning deformation predominated, whereas dislocation slip deformation dominated when twinning deformation reached saturation. The trends observed in the fractions of 2°-5°, 5°-15°, and 15°-180° grain boundaries confirmed that twinning deformation dominated the first stage.
基金This work was financially supported by the National Natural Science Foundation of China （No.20271001）.
文摘A novel method for controlled synthesis of crystalline molybdenum dioxides nanowhiskers （whisker-MoO2） by using moderate reductive and precursor ion under hydrothermal conditions is reported. The result shows that the as-obtained samples have a monoclinic structure, and the whisker-MoO2 is composed of nanowires with diameters of ca. 20 nm. Formation of whisker-MoO2 was through a typical precursor-reduction process, in which cetyltrimethylammonium bromide （CTAB） served as a cationic surfactant and acetone as a reductant. The electrochemical behavior of whisker-MoO2 was studied.
