Au]Cel_xZrxO2 catalysts （x = 0-0.8） were prepared by a deposition-precipitation method using Cel_xZrxO2 nanoparticles as supports with variable Ce and Zr contents. Their structures were characterized by complimentar...Au]Cel_xZrxO2 catalysts （x = 0-0.8） were prepared by a deposition-precipitation method using Cel_xZrxO2 nanoparticles as supports with variable Ce and Zr contents. Their structures were characterized by complimentary means such as X-ray diffraction, Raman, scanning trans- mission electron microscopy and X-ray photoelectron spectroscopy （XPS）. These Au catalysts possessed similar sizes and crystalline phases of Cel_xZrzO2 supports as well as similar sizes and oxidation states of Au nanoparticles. The oxidation state of Au nanoparticles was dominated by Au~ especially in CO oxidation. Their activities were examined in CO oxidation at different temperatures in the range of 303-333 K. The CO oxidation rates normalized per Au atoms increased with the increasing Ce contents, and reached the maximum value over Au/CeO2. Such change was in parallel with the change in the oxygen storage capacity values, i.e. the amounts of active oxygen species on Au/Cel_zZrzO2 catalysts. The excellent correlation between the two properties of the catalysts suggests that the intrinsic support effects on the CO oxidation rates is related to the effects on the adsorption and activation of O2 on Au/Cel_xZrxO2 catalysts. Such understanding on the support effects may be useful for designing more active Au catalysts, for example, by tuning the redox properties of oxide supports.展开更多
The valorization of eggshell waste as bio-calcium oxide is crucial for pollution prevention and supporting sustainable development.There are several reports on the thermal conversion of eggshell waste to calcium oxide...The valorization of eggshell waste as bio-calcium oxide is crucial for pollution prevention and supporting sustainable development.There are several reports on the thermal conversion of eggshell waste to calcium oxide for the partial or complete substitution of natural lime applications.However,this paper reports the thermal decomposition of large amounts of hatchery eggshell waste on an industrial-scale car bottom furnace for the first time.The hatchery eggshell waste was sundried and placed into five stacked trays in the car bottom furnace.The calcination of the eggshell waste was conducted at 900℃ for 3 and 4 h under an atmosphere of air.Both the physical and chemical properties of the eggshell samples and the bio-quicklime products were carefully examined by TGA,SEM,XRD,FTIR,and XRF.The results demonstrate that the purity of calcium oxide in the quicklime products increased from 79%to 87%upon increasing the calcination time from 3 to 4 h.However,the color of the calcined eggshell samples at the surface of the pile was white while the color of the product beneath the surface was black or dark gray.The purity of the calcium oxide of both the black and white calcined samples was 76.4%and 91.5%,respectively.These results indicate the limited efficacy of the car bottom furnace for thermal decomposition of the large amount of eggshell waste to calcium oxide.Additionally,the production cost of bio-calcium oxide is approximately twice the cost of industrial grade lime.For further industrial applications,the furnace should contain the mixing equipment for improving the thermal decomposition of the large pile of eggshell waste.Furthermore,the oil burner system may be used in order to reduce fuel costs.展开更多
The effect of CeO2 and CaO promoters on the ignition performance over Ni/MgO-Al2O3 catalyst for the partial oxidation of methane （POM） to synthesis gas was investigated. It was found that the POM reaction could not ...The effect of CeO2 and CaO promoters on the ignition performance over Ni/MgO-Al2O3 catalyst for the partial oxidation of methane （POM） to synthesis gas was investigated. It was found that the POM reaction could not be ignited over lwt%Ni/MgO-Al2O3 catalyst without the promoters in the temperature range from 773 K to 1073 K. CeO2 and CaO promoters enhanced the ignition performance and the POM reactivity of lwt%Ni/MgO-Al2O3 catalyst remarkably. Moreover, the improving effect became greater with the increase of the promoter content under the investigated reactiorrconditions. The modification effects of CeO2 and CaO promoters were closely related to the concentration and reducibility of the surface and bulk oxygen species.展开更多
The activity and thermal stability of Pd/Al2O3 and Pd/（Al2O3＋MOx） （M=Ca, La, Ce） palladium catalysts in the reaction of complete oxidation of methane are presented in this study. The catalyst supports were prepar...The activity and thermal stability of Pd/Al2O3 and Pd/（Al2O3＋MOx） （M=Ca, La, Ce） palladium catalysts in the reaction of complete oxidation of methane are presented in this study. The catalyst supports were prepared by sol-gel method and they were dried either conventionally or with supercritical carbon dioxide. Then they were impregnated with palladium nitrate solution. The catalysts with unmodified alumina had a high surface area. The activity and thermal stability of the aluminasupported catalyst was also very high. The introduction of calcium, lanthanum, or cerium oxide into alumina support caused a decrease of the surface area in the way dependent on the support precursor drying method. These modifiers decreased the activity of palladium catalysts, and they required higher temperatures for the complete oxidation of methane than unmodified Pd/Al2O3. The improvement of the palladium activity by lanthanum and cerium support modifier was observed only at low temperatures of the reaction.展开更多
Mesoporous silica-zirconia supported phosphotungstic acid was synthesized by evaporation induced self-assembly method and used as oxidative desulfurization catalysts. The structural properties of as-prepared catalysts...Mesoporous silica-zirconia supported phosphotungstic acid was synthesized by evaporation induced self-assembly method and used as oxidative desulfurization catalysts. The structural properties of as-prepared catalysts were characterized using various analytical techniques including X-ray diffraction, transmission electron microscopy, Fourier transform infrared spectroscopy, and nitrogen adsorption desorption. The experimental results showed that HPW was highly dispersed on mesoporous framework. The surface acidity of catalysts was analyzed by FTIR measurement of adsorbed pyridine.The surface Lewis acidity was improved with increasing the content of zirconium in the samples. The mesoporous composites were used as catalysts with H2O2 as oxidant for oxidative desulfurization of model fuel. The catalytic activity results showed that the surface Lewis acid sites acted as selective adsorption active sites for dibenzothiophene, which facilitated the sulfur removal from model fuel in the presence of arene. A slight decrease in activity of the recovered catalyst used in the proceeding rounds indicated the reusability of the catalyst.展开更多
Tars and alkali ashes from biomass gasification processes currently constitute one of the major problems in biomass valorisation, generating clogging of filters and issues related with the purity of syngas production....Tars and alkali ashes from biomass gasification processes currently constitute one of the major problems in biomass valorisation, generating clogging of filters and issues related with the purity of syngas production. To date, these waste residues find no useful applications and they are generally disposed upon generation in the gasification process. A detailed analysis of these residues pointed out the presence of high quantities of Ca （〉30 wt%）. TG experiments indicated that a treatment under air at moderate temperatures （400-800 ~C） decomposed the majority of carbon species, while XRD indicated the presence of a crystalline CaO phase. CaO enriched valorized materials turned out to be good heterogeneous catalysts for biodiesel production from vegetable oils, providing moderate to good activities （50%-70% after 12 h） to fatty acid methyl esters in the transesterification of sunflower oil with methanol.展开更多
Auto-thermal reforming of methane, combining partial oxidation and reforming of methane with CO2 or steam, was carried out with Pt/Al2O3, Pt/ZrO2 and Pt/CeO2 catalysts, in a temperature range of 300-900℃. The auto-th...Auto-thermal reforming of methane, combining partial oxidation and reforming of methane with CO2 or steam, was carried out with Pt/Al2O3, Pt/ZrO2 and Pt/CeO2 catalysts, in a temperature range of 300-900℃. The auto-thermal reforming occurs in two simultaneous stages, namely, total combustion of methane and reforming of the unconverted methane with steam and CO2, with the O2 conversion of 100% starting from 450℃. For combination with CO2 reforming, the Pt/CeO2 catalyst showed the lowest initial activity at 800℃, and the highest stability over 40 h on-stream. This catalyst also presented the best performance for the reaction with steam at 800℃. The higher resistance to coke formation of the catalyst supported on ceria is due to the metal-support interactions and the higher mobility of oxygen in the oxide lattice.展开更多
基金the National Natural Science Foundation of China(20825310,20973011)the National Basic Research Program of China(973 Program,2011CB201400,2011CB808700)
文摘Au]Cel_xZrxO2 catalysts （x = 0-0.8） were prepared by a deposition-precipitation method using Cel_xZrxO2 nanoparticles as supports with variable Ce and Zr contents. Their structures were characterized by complimentary means such as X-ray diffraction, Raman, scanning trans- mission electron microscopy and X-ray photoelectron spectroscopy （XPS）. These Au catalysts possessed similar sizes and crystalline phases of Cel_xZrzO2 supports as well as similar sizes and oxidation states of Au nanoparticles. The oxidation state of Au nanoparticles was dominated by Au~ especially in CO oxidation. Their activities were examined in CO oxidation at different temperatures in the range of 303-333 K. The CO oxidation rates normalized per Au atoms increased with the increasing Ce contents, and reached the maximum value over Au/CeO2. Such change was in parallel with the change in the oxygen storage capacity values, i.e. the amounts of active oxygen species on Au/Cel_zZrzO2 catalysts. The excellent correlation between the two properties of the catalysts suggests that the intrinsic support effects on the CO oxidation rates is related to the effects on the adsorption and activation of O2 on Au/Cel_xZrxO2 catalysts. Such understanding on the support effects may be useful for designing more active Au catalysts, for example, by tuning the redox properties of oxide supports.
文摘The valorization of eggshell waste as bio-calcium oxide is crucial for pollution prevention and supporting sustainable development.There are several reports on the thermal conversion of eggshell waste to calcium oxide for the partial or complete substitution of natural lime applications.However,this paper reports the thermal decomposition of large amounts of hatchery eggshell waste on an industrial-scale car bottom furnace for the first time.The hatchery eggshell waste was sundried and placed into five stacked trays in the car bottom furnace.The calcination of the eggshell waste was conducted at 900℃ for 3 and 4 h under an atmosphere of air.Both the physical and chemical properties of the eggshell samples and the bio-quicklime products were carefully examined by TGA,SEM,XRD,FTIR,and XRF.The results demonstrate that the purity of calcium oxide in the quicklime products increased from 79%to 87%upon increasing the calcination time from 3 to 4 h.However,the color of the calcined eggshell samples at the surface of the pile was white while the color of the product beneath the surface was black or dark gray.The purity of the calcium oxide of both the black and white calcined samples was 76.4%and 91.5%,respectively.These results indicate the limited efficacy of the car bottom furnace for thermal decomposition of the large amount of eggshell waste to calcium oxide.Additionally,the production cost of bio-calcium oxide is approximately twice the cost of industrial grade lime.For further industrial applications,the furnace should contain the mixing equipment for improving the thermal decomposition of the large pile of eggshell waste.Furthermore,the oil burner system may be used in order to reduce fuel costs.
文摘The effect of CeO2 and CaO promoters on the ignition performance over Ni/MgO-Al2O3 catalyst for the partial oxidation of methane （POM） to synthesis gas was investigated. It was found that the POM reaction could not be ignited over lwt%Ni/MgO-Al2O3 catalyst without the promoters in the temperature range from 773 K to 1073 K. CeO2 and CaO promoters enhanced the ignition performance and the POM reactivity of lwt%Ni/MgO-Al2O3 catalyst remarkably. Moreover, the improving effect became greater with the increase of the promoter content under the investigated reactiorrconditions. The modification effects of CeO2 and CaO promoters were closely related to the concentration and reducibility of the surface and bulk oxygen species.
文摘The activity and thermal stability of Pd/Al2O3 and Pd/（Al2O3＋MOx） （M=Ca, La, Ce） palladium catalysts in the reaction of complete oxidation of methane are presented in this study. The catalyst supports were prepared by sol-gel method and they were dried either conventionally or with supercritical carbon dioxide. Then they were impregnated with palladium nitrate solution. The catalysts with unmodified alumina had a high surface area. The activity and thermal stability of the aluminasupported catalyst was also very high. The introduction of calcium, lanthanum, or cerium oxide into alumina support caused a decrease of the surface area in the way dependent on the support precursor drying method. These modifiers decreased the activity of palladium catalysts, and they required higher temperatures for the complete oxidation of methane than unmodified Pd/Al2O3. The improvement of the palladium activity by lanthanum and cerium support modifier was observed only at low temperatures of the reaction.
基金Funded by the National Natural Science Foundation of China(No.21106008)the Petro China Innovation Foundation(No.2013D-5006-0405)
文摘Mesoporous silica-zirconia supported phosphotungstic acid was synthesized by evaporation induced self-assembly method and used as oxidative desulfurization catalysts. The structural properties of as-prepared catalysts were characterized using various analytical techniques including X-ray diffraction, transmission electron microscopy, Fourier transform infrared spectroscopy, and nitrogen adsorption desorption. The experimental results showed that HPW was highly dispersed on mesoporous framework. The surface acidity of catalysts was analyzed by FTIR measurement of adsorbed pyridine.The surface Lewis acidity was improved with increasing the content of zirconium in the samples. The mesoporous composites were used as catalysts with H2O2 as oxidant for oxidative desulfurization of model fuel. The catalytic activity results showed that the surface Lewis acid sites acted as selective adsorption active sites for dibenzothiophene, which facilitated the sulfur removal from model fuel in the presence of arene. A slight decrease in activity of the recovered catalyst used in the proceeding rounds indicated the reusability of the catalyst.
基金the Gobierno de Espaa for the Provision of a Ramon y Cajal Contract (ref. RYC-2009-04199).supported by the Projects CTQ2010-18126 and CTQ2011 28954-C02-02 (MICINN) as well as P10-FQM-6711 (Consejeria de Ciencia e Innovacion,Junta de Andalucia)
文摘Tars and alkali ashes from biomass gasification processes currently constitute one of the major problems in biomass valorisation, generating clogging of filters and issues related with the purity of syngas production. To date, these waste residues find no useful applications and they are generally disposed upon generation in the gasification process. A detailed analysis of these residues pointed out the presence of high quantities of Ca （〉30 wt%）. TG experiments indicated that a treatment under air at moderate temperatures （400-800 ~C） decomposed the majority of carbon species, while XRD indicated the presence of a crystalline CaO phase. CaO enriched valorized materials turned out to be good heterogeneous catalysts for biodiesel production from vegetable oils, providing moderate to good activities （50%-70% after 12 h） to fatty acid methyl esters in the transesterification of sunflower oil with methanol.
文摘Auto-thermal reforming of methane, combining partial oxidation and reforming of methane with CO2 or steam, was carried out with Pt/Al2O3, Pt/ZrO2 and Pt/CeO2 catalysts, in a temperature range of 300-900℃. The auto-thermal reforming occurs in two simultaneous stages, namely, total combustion of methane and reforming of the unconverted methane with steam and CO2, with the O2 conversion of 100% starting from 450℃. For combination with CO2 reforming, the Pt/CeO2 catalyst showed the lowest initial activity at 800℃, and the highest stability over 40 h on-stream. This catalyst also presented the best performance for the reaction with steam at 800℃. The higher resistance to coke formation of the catalyst supported on ceria is due to the metal-support interactions and the higher mobility of oxygen in the oxide lattice.
