排序方式: 共有8条查询结果,搜索用时 0 毫秒
1
1.
混合稀土的添加对PtSnNa/ZSM-5催化剂丙烷脱氢性能的影响 总被引:1,自引:0,他引:1
The influence of mischmetal addition on physicochemical properties of PtSnNa/ZSM-5 catalyst was studied by means of XRF,H 2 chemisorption,XRD,TPR,NH 3-TPD and TPO techniques.The results showed that the presence of mischmetal had an obvious impact on the catalytic performance of the PtSnNa/ZSM-5 catalyst.A suitable content of mischmetal not only could enhance the interactions between Pt species and the support,but also inhibit the formation of coke during the reaction,thus improving the catalytic activity and stability.In our experiments,when the content of mischmetal was 3m%,the catalyst exhibited best catalytic performance.However,the continuous addition of mischmetal could promote the reduction of Sn species to metallic tin,which was disadvantageous to the reaction. 相似文献
2.
3.
Solid-state grinding is a simple and effective method to introduce guest species into the channels of microporous materials through filling.The structure and the surface acidity of the materials were obtained from BET isotherms and NH3-TPD, respectively.XRD, UV-vis, UV diffuse-reflectance, and TEM were used to characterize the phases, and the morphology, respectively.The clustered layers of MgO-Al2O3phases were formed in the internal pore surface and were highly dispersed inside the channels of the ZSM-5 host.So the volume of MgO-Al2O3/ZSM-5 composite was larger than the ZSM-5 zeolite itself and some mesoporous channels appeared when Mg/Al species entered the channels.Meanwhile, new acid sites emerged in MgO-Al2O3/ZSM-5 composite and the acid amount of the sample changed.The improved Pt dispersion and the increased acid content would cause the increase of propane conversion and the modification of selectivity during the reaction. 相似文献
4.
用于烷基化C9芳烃分离制备均三甲苯的磷钨酸/高岭土催化剂的研究 总被引:1,自引:0,他引:1
用浸渍法制备了磷钨酸/高岭土催化剂,用XRD、NH3-TPD等方法对其进行了表征,并考察其催化C9混合芳烃(C9)烷基化反应的性能。结果表明,磷钨酸和高岭土之间存在三种不同的作用形式,当磷钨酸负载量小于10%时形成饱和的磷钨酸盐;中等负载量(20%~40%)时形成酸性较强的不饱和磷钨酸盐;负载量大于40%时,在不饱和磷钨酸盐表面形成磷钨酸晶体。随着磷钨酸负载量的增加,三甲苯的转化率和均三甲苯与甲乙苯的比值逐渐增大,催化剂的烷基化能力增强,当磷钨酸负载量大于40%后,烷基化能力下降。当催化剂磷钨酸的负载量为40%时,反应60min分离后可得到纯度为99.2%的均三甲苯,均三甲苯收率为87.3%。 相似文献
5.
6.
镓对PtSnNa/ZSM-5催化剂丙烷脱氢反应性能的影响 总被引:1,自引:0,他引:1
PtSnNaGa/ZSM-5 catalysts with different contents of Ga were prepared and characterized by X-ray diffraction (XRD), nitrogen adsorption, hydrogen chemisorption, ammonia temperature-programmed desorption (NH3-TPD), hydrogen temperature-programmed reduction (H2-TPR), and temperature-programmed oxidation (TPO) techniques. The performances of these catalysts for propane dehydrogenation were investigated. The test results indicated that the addition of Ga not only could improve the catalytic stability and propene selectivity, but also could effectively prevent the catalysts from coking. It was found that the PtSnNaGa(0.5 m%)/ZSM-5 catalyst exhibited the best performance in terms of propene selectivity and propane conversion. The high catalytic performance was most probably attributed to the presence of Ga that could strength- en the interaction between metals and the support to stabilize the catalytic active sites. 相似文献
7.
通过对HZSM-5分子筛的碱液处理,制得具有微-介孔结构的ATZ多孔材料。由XRD、N2吸附脱附和NH3-TPD等表征手段的结果可知,碱处理后HZSM-5的物理化学性质变化明显,ATZ具有较高的外比表面积和较低的酸量。相比PtSn/HZSM-5催化剂,PtSn/ATZ显示了较高的丙烷脱氢性能,这可能是由于ATZ具有相对降低的酸量所致。此外,ATZ上介孔的存在有利于Pt金属颗粒的分散,减少了脱氢反应过程中Pt金属颗粒表面积碳的产生,从而提高了催化剂的脱氢性能。 相似文献
8.
The effects of the sequence for impregnation of metal precursors on the performance of PtSnNa/ZSM-5 catalyst for propane dehydrogenation to propene were studied in this paper. Some methods such as XRD, TPDA, BET, H2-TPR, XPS, ICP, TEM and hydrogen chemisorption were used to characterize the catalysts. The structure of ZSM-5 zeolite was not destroyed by the introduction of metal components. Meanwhile the different impregnation sequence of metal precursors could affect the behavior of Sn4+ species entering the ZSM-5 channel, and the interaction between platinum and tin species, as well as the degree for reduction of Pt and Sn components. As a result, the prepared catalysts exhibited different reac- tion activity and selectivity. Compared with the co-impregnation treated catalyst, the catalysts prepared by the sequential impregnation method showed better catalytic activity in propane dehydrogenation, especially the one prepared through impregnation with tin precursor at first. Finally, a model for the effect of impregnation sequence on the distribution of Pt and Sn species in PtSnNa/ZSM-5 catalyst was proposed. 相似文献
1