Sn-Ce-O binary catalysts with different Sn/Ce molar ratios were prepared with co-precipitation method and applied for CO and CH4 oxidation. The catalysts were characterized by means of Nz-BET, XRD and H2-TPR technique...Sn-Ce-O binary catalysts with different Sn/Ce molar ratios were prepared with co-precipitation method and applied for CO and CH4 oxidation. The catalysts were characterized by means of Nz-BET, XRD and H2-TPR techniques. It was found that for those Sn rich sam- pies such as SnCe91 and SnCe73, Ce cations were doped into the matrix of tetragonal rutile SnO2 to form SnO2-based solid solution. As a consequence, the oxidation activity as well as the thermal stability was significantly improved compared with pure SnO2. In contrast, for Ce rich samples such as SnCel9, SnCe37 and SnCe55, though the thermal stability was improved, the activity was worse than SnO2, due to the presence of much less amount of active oxygen species. Co-precipitation was found to be the best method to prepare Sn-Ce binary catalysts among all of the methods tried in this study.展开更多
In this paper,a series of Rh/CeO_(2) catalysts with three-dimensional porous nanorod frameworks and large specific surface area were prepared by chemical dealloying Al–Ce–Rh precursor alloys and then calcining in pu...In this paper,a series of Rh/CeO_(2) catalysts with three-dimensional porous nanorod frameworks and large specific surface area were prepared by chemical dealloying Al–Ce–Rh precursor alloys and then calcining in pure O_(2).The effects of the Rh content and calcination temperature on CO oxidation and CH_(4) combustion were studied,and the results reveal that the Rh/CeO_(2) catalysts produced by dealloying melt-spun Al_(91.3)Ce_(8)Rh_(0.7) alloy ribbons and then calcining at 500℃ exhibit the best catalytic activity,the reaction temperatures for the complete conversion of CO and CH_(4) are as low as 90 and 400℃,respectively.Furthermore,after 150 h of continuous testing at high concentrations of H2O and CO_(2),the nature of the catalyst is not irreversibly destroyed and can still return to its initial level of activity.This excellent catalytic activity is attributed to a portion of Rh being uniformly distributed on the CeO_(2) nanorod surface in the form of nanoparticles,forming strong Rh–CeO_(2) interfacial synergy.Another portion of Rh permeated into the CeO_(2) lattice,which results in a significant increase in the number of oxygen vacancies in CeO_(2),thus allowing more surface active oxygen to be adsorbed and converted from the gas phase.Moreover,the catalytic reaction can proceed even in an oxygen-free environment due to the excellent oxygen storage performance of the Rh/CeO_(2) catalyst.展开更多
With the development of reaction kinetics and transfer science, the modeling of NOx formation plays more and more important roles in the protection of environment and the design of combustion reactors; in this case,tu...With the development of reaction kinetics and transfer science, the modeling of NOx formation plays more and more important roles in the protection of environment and the design of combustion reactors; in this case,turbulence-chemistry model and NOx formation model are the two most important aspects. For thermal NOx mechanism, this article studied the CH4/air system and applied a set of latest NO formation rate constants published at the Leed University which replaced the original model code in FLUENT to increase its precision on prediction of NO concentration. The realizable k-ε model, Reynold Stress model and standard k-ε model were also investigated to predict the turbulent combustion reaction, which indicated that the simulation results of velocities, temperatures and concentrations of combustion productions by the standard k-ε model were in good accordance with the experimental data. With the application of the simulation results to the experimental data to fit some important kinetic parameters in the equation of O atom model and revision of the equation later, this article obtained a new NO formation rate model. It has been proved that the prediction of the developed model coincides well with the measurements.展开更多
With the development of reaction kinetics and transfer science, the modeling of NOx formation plays more and more important roles in the protection of environment and the design of combustion reactors; in this case, t...With the development of reaction kinetics and transfer science, the modeling of NOx formation plays more and more important roles in the protection of environment and the design of combustion reactors; in this case, turbulence-chemistry model and NOx formation model are the two most important aspects. For thermal NOx mechanism, this article studied the CH4/air system and applied a set of latest NO formation rate constants published at the Leed University which replaced the original model code in FLUENT to increase its precision on prediction of NO concentration. The realizable k-ε model, Reynold Stress model and standard k-ε model were also investigated to predict the turbulent combustion reaction, which indicated that the simulation results of velocities, temperatures and concentrations of combustion productions by the standard k-ε model were in good accordance with the experi- mental data. With the application of the simulation results to the experimental data to fit some important kinetic pa- rameters in the equation of O atom model and revision of the equation later, this article obtained a new NO forma- tion rate model. It has been proved that the prediction of the developed model coincides well with the measure- ments.展开更多
文摘Sn-Ce-O binary catalysts with different Sn/Ce molar ratios were prepared with co-precipitation method and applied for CO and CH4 oxidation. The catalysts were characterized by means of Nz-BET, XRD and H2-TPR techniques. It was found that for those Sn rich sam- pies such as SnCe91 and SnCe73, Ce cations were doped into the matrix of tetragonal rutile SnO2 to form SnO2-based solid solution. As a consequence, the oxidation activity as well as the thermal stability was significantly improved compared with pure SnO2. In contrast, for Ce rich samples such as SnCel9, SnCe37 and SnCe55, though the thermal stability was improved, the activity was worse than SnO2, due to the presence of much less amount of active oxygen species. Co-precipitation was found to be the best method to prepare Sn-Ce binary catalysts among all of the methods tried in this study.
基金Project supported by the National Natural Science Foundation of China (51771141,51671155)。
文摘In this paper,a series of Rh/CeO_(2) catalysts with three-dimensional porous nanorod frameworks and large specific surface area were prepared by chemical dealloying Al–Ce–Rh precursor alloys and then calcining in pure O_(2).The effects of the Rh content and calcination temperature on CO oxidation and CH_(4) combustion were studied,and the results reveal that the Rh/CeO_(2) catalysts produced by dealloying melt-spun Al_(91.3)Ce_(8)Rh_(0.7) alloy ribbons and then calcining at 500℃ exhibit the best catalytic activity,the reaction temperatures for the complete conversion of CO and CH_(4) are as low as 90 and 400℃,respectively.Furthermore,after 150 h of continuous testing at high concentrations of H2O and CO_(2),the nature of the catalyst is not irreversibly destroyed and can still return to its initial level of activity.This excellent catalytic activity is attributed to a portion of Rh being uniformly distributed on the CeO_(2) nanorod surface in the form of nanoparticles,forming strong Rh–CeO_(2) interfacial synergy.Another portion of Rh permeated into the CeO_(2) lattice,which results in a significant increase in the number of oxygen vacancies in CeO_(2),thus allowing more surface active oxygen to be adsorbed and converted from the gas phase.Moreover,the catalytic reaction can proceed even in an oxygen-free environment due to the excellent oxygen storage performance of the Rh/CeO_(2) catalyst.
文摘With the development of reaction kinetics and transfer science, the modeling of NOx formation plays more and more important roles in the protection of environment and the design of combustion reactors; in this case,turbulence-chemistry model and NOx formation model are the two most important aspects. For thermal NOx mechanism, this article studied the CH4/air system and applied a set of latest NO formation rate constants published at the Leed University which replaced the original model code in FLUENT to increase its precision on prediction of NO concentration. The realizable k-ε model, Reynold Stress model and standard k-ε model were also investigated to predict the turbulent combustion reaction, which indicated that the simulation results of velocities, temperatures and concentrations of combustion productions by the standard k-ε model were in good accordance with the experimental data. With the application of the simulation results to the experimental data to fit some important kinetic parameters in the equation of O atom model and revision of the equation later, this article obtained a new NO formation rate model. It has been proved that the prediction of the developed model coincides well with the measurements.
文摘With the development of reaction kinetics and transfer science, the modeling of NOx formation plays more and more important roles in the protection of environment and the design of combustion reactors; in this case, turbulence-chemistry model and NOx formation model are the two most important aspects. For thermal NOx mechanism, this article studied the CH4/air system and applied a set of latest NO formation rate constants published at the Leed University which replaced the original model code in FLUENT to increase its precision on prediction of NO concentration. The realizable k-ε model, Reynold Stress model and standard k-ε model were also investigated to predict the turbulent combustion reaction, which indicated that the simulation results of velocities, temperatures and concentrations of combustion productions by the standard k-ε model were in good accordance with the experi- mental data. With the application of the simulation results to the experimental data to fit some important kinetic pa- rameters in the equation of O atom model and revision of the equation later, this article obtained a new NO forma- tion rate model. It has been proved that the prediction of the developed model coincides well with the measure- ments.
