The structure and catalytic properties of PtSn catalysts supported on SUZ-4 and ZSM-5 zeolite have been studied by using various experimental techniques including XRD,nitrogen adsorption,NH3-TPD,TG,H2-TPR and TPO tech...The structure and catalytic properties of PtSn catalysts supported on SUZ-4 and ZSM-5 zeolite have been studied by using various experimental techniques including XRD,nitrogen adsorption,NH3-TPD,TG,H2-TPR and TPO techniques combined with propane dehydrogenation tests.It has been shown that SUZ-4-supported PtSnNa(PtSnNa/SUZ-4) was determined to be a better catalyst for propane dehydrogenation than conventional catalysts supported on ZSM-5,owing to its higher catalytic activity and stability.Dibenzothiophene poisoning experiments were performed to investigate the detailed structures of the two supported catalysts.The characterization of the two catalysts indicates that the distribution of Pt on the porous support affects the activity.In contrast to ZSM-5-supported catalysts,Pt particles on the PtSnNa/SUZ-4 are primarily dispersed over the external surface and are not as readily deactivated by carbon deposition.This is because that the strong acid sites of the SUZ-4 zeolite evidently prevented the impregnation of the Pt precursor H_2PtCl_6 into the zeolite.In contrast,the weak acid sites of the ZSM-5 zeolite led to more of the precursor entering the zeolite tunnels,followed by transformation to highly dispersed Pt clusters during calcination.In the case of the PtSnNa/ZSM-5,the interactions between Sn oxides and the support were lessened,owing to the weaker acidity of the ZSM-5 zeolite.The dispersed Sn oxides were therefore easier to reduce to the metallic state,thus decreasing the catalytic activity for hydrocarbon dehydrogenation.展开更多
The combustion characteristics of NaOH treated and untreated Xilihaote lignite was investigated by thermogravimetric analysis.The relationship between physico-chemical properties,including the ash content,oxygen-conta...The combustion characteristics of NaOH treated and untreated Xilihaote lignite was investigated by thermogravimetric analysis.The relationship between physico-chemical properties,including the ash content,oxygen-containing functional groups,mean pore diameter and specific surface area and combustion performance,was also studied in this paper.Combustion kinetic parameters were calculated through Coasts Redfern Method.The results show that ignition of treated samples takes place at higher temperature compared to raw lignite,and peak temperature also occurs at higher temperature.The maximum combustion rate of the sample,which was treated by 0.01 mol/L NaOH lignite,was the biggest.Reaction orders of 0.6,2.0,and 0.8 were found to be effective mechanism for definite three temperature regions.Average activation energies of these three temperature regions of XLHTR,XLHT0.01,XLHT0.50 and XLTH1.00 are 19.17,23.87,10.77,and 10.93 kJ/mol,respectively.Treatment of lignite with NaOH can reduce the reactivity of lignite at proper concentration.展开更多
基金supported by the Jiangsu Planned Projects for Postdoctoral Research Funds(1301080C)NNSFC(21202141,21173182)+1 种基金Key Science&Technology Specific Projects of Yangzhou(YZ20122029)the Innovation Foundation of Yangzhou University(2015CXJ009)~~
文摘The structure and catalytic properties of PtSn catalysts supported on SUZ-4 and ZSM-5 zeolite have been studied by using various experimental techniques including XRD,nitrogen adsorption,NH3-TPD,TG,H2-TPR and TPO techniques combined with propane dehydrogenation tests.It has been shown that SUZ-4-supported PtSnNa(PtSnNa/SUZ-4) was determined to be a better catalyst for propane dehydrogenation than conventional catalysts supported on ZSM-5,owing to its higher catalytic activity and stability.Dibenzothiophene poisoning experiments were performed to investigate the detailed structures of the two supported catalysts.The characterization of the two catalysts indicates that the distribution of Pt on the porous support affects the activity.In contrast to ZSM-5-supported catalysts,Pt particles on the PtSnNa/SUZ-4 are primarily dispersed over the external surface and are not as readily deactivated by carbon deposition.This is because that the strong acid sites of the SUZ-4 zeolite evidently prevented the impregnation of the Pt precursor H_2PtCl_6 into the zeolite.In contrast,the weak acid sites of the ZSM-5 zeolite led to more of the precursor entering the zeolite tunnels,followed by transformation to highly dispersed Pt clusters during calcination.In the case of the PtSnNa/ZSM-5,the interactions between Sn oxides and the support were lessened,owing to the weaker acidity of the ZSM-5 zeolite.The dispersed Sn oxides were therefore easier to reduce to the metallic state,thus decreasing the catalytic activity for hydrocarbon dehydrogenation.
基金the National Basic Research Program of China (No.2012CB214901)the National Natural Science Foundation of China (No.51274197)the Fundamental Research Funds for the Central Universities (No.2010LKHX07) for the financial support
文摘The combustion characteristics of NaOH treated and untreated Xilihaote lignite was investigated by thermogravimetric analysis.The relationship between physico-chemical properties,including the ash content,oxygen-containing functional groups,mean pore diameter and specific surface area and combustion performance,was also studied in this paper.Combustion kinetic parameters were calculated through Coasts Redfern Method.The results show that ignition of treated samples takes place at higher temperature compared to raw lignite,and peak temperature also occurs at higher temperature.The maximum combustion rate of the sample,which was treated by 0.01 mol/L NaOH lignite,was the biggest.Reaction orders of 0.6,2.0,and 0.8 were found to be effective mechanism for definite three temperature regions.Average activation energies of these three temperature regions of XLHTR,XLHT0.01,XLHT0.50 and XLTH1.00 are 19.17,23.87,10.77,and 10.93 kJ/mol,respectively.Treatment of lignite with NaOH can reduce the reactivity of lignite at proper concentration.