催化剂PPT

单击此处编辑母版标题样式,单击此处编辑母版文本样式,第二级,第三级,第四级,第五级,2017/12/8,#,单击此处编辑母版文本样式,第二级,第三级,第四级,第五级,2017/12/8,#,单击此处编辑母版标题样式,Design of Highly Efficient Pt-SnO,2,Hydrogenation Nanocatalysts using PtSn CoreShell Nanoparticles,Characterization,synthesis,1.,2.,Characterization,XRD,01,TEM,02,XPS,03,TPO,04,DRIFT-IR,05,XRD patterns showing (a) Pt NPs, (b) PtSn NPs, and (c),Pt-SnO,2,NPs obtained by calcination of PtSn NPs at 500,for 3 h.,As shown in Figure 1b, nearly pure Pt diffractions were observed and Sn diffractions were invisible for PtSn NPs,.,The clear Pt and SnO2 diffractions for Pt-SnO2 NPs in Figure 1c are consistent with the presence of Sn in the PtSn NPs, although the Sn diffractions were not observed in Figure 1b.,XRD patterns of individual Pt, assynthesized PtSn, and Pt-SnO2 NPs obtained by calcination of PtSn NPs,TEM studies of Pt NPs, PtSn NPs, Pt/Al,2,O,3, and PtSnO,2,/Al,2,O,3,Small,percentages of Sn,+,and Pt,2+,are observed for PtSn NPs and Pt,2+,、,Pt,4+,are observed for Pt-SnO,2,NPs presumably due to the,exposure of NPs to,air,.,The,binding energies at 486.6/494.9 eV,in Figure b,can be assigned to,3d5/2/3d3/2,of Sn,4+, which is consistent with the XPS database of SnO,2,and their XRD,patterns,.,XPS spectra,showing (a) as-synthesized PtSn and (b) Pt-SnO2,The higher Sn/Pt ratio for PtSn by XPS is consistent with,PtSn coreshell,structures,The,Pt/oxidized Pt ratio of 27.68/72.32 for Pt-SnO2 indicates that more surface Pt atoms are oxidized by,calcination,Sn/Pt,ratio of 2.79/ 1.00 by XPS suggests heteroaggregate nanostructures with a distribution of,SnO2 on Pt surfaces.,TPO study,of PtSn/Al2O3,further c,onrms,the complete oxidation of Sn of PtSn below,300,DRIFT-IR spectra with CO probes,Only CO bands,on Pt are observed, since CO is not adsorbed on tin,linear CO on Pt step and kink sites,the surfaces mainly consist of Sn and the majority of Pt is in the cores,linear CO on Pt step and kink sites,linear CO on Pt terrace sites,Catalytic Performance,Pt-SnO,2,/Al,2,O,3,with a Pt/Sn ratio of 1/1 has the,highest catalytic activity,and excellent,catalytic selectivity,Catalytic Performance,Pt-SnO,2,/Al,2,O,3,nanocatalysts had,higher activity and selectivity,than,Pt/Al,2,O,3,nanocatalysts, with the exception that the selectivity of catalytic m-CNB,hydrogenation,over Pt-SnO,2,/Al,2,O,3,is lower than that over Pt/Al,2,O,3,.,Catalytic Performance,Pt-SnO2/Al2O3,nanocatalysts had,higher activity,than,Pt/Al2O3,nanocatalysts, while the selectivities over Pt-SnO2/ Al2O3 and Pt/Al2O3 are the same (100%),Catalytic Performance,the,catalytic activities and selectivities for hydrogenation of nitrobenzaldehyde and nitroacetophenone over Pt-SnO2/Al2O3 are higher than those over Pt/Al2O3 except that the catalytic activities for p-NAP hydrogenation over Pt-SnO2/Al2O3 and Pt/Al2O3 are the same (100%).,Catalytic,Stability of Pt-SnO2/Al2O3,Within,the rst ve cycles, the catalytic activity of Pt-SnO2/Al2O3 was stable, and the catalytic selectivity slightly increased, suggesting a,good structural stability,of Pt-SnO2 heteroaggregate nanocatalysts,theoretical,calculations(using DET),the,partial coverage of Pt (111) surfaces with SnO2 slightly promotes the H adsorption on Pt (111),surfaces.,the Pt-SnO2 nanostructures can slightly facilitate the adsorption of,o-CNB.,the cooperative PtSnO2 interaction can desorpt products easier, resulting in more catalytic surface being available and a fast reaction,rate,the,enhanced catalytic performance of Pt-SnO2/Al2O3 nanocatalysts originates from the cooperative interaction between Pt and SnO2 inside the heteroaggregate nanostructures,Conclusion,1,、,DRIFT-IR,with CO probes, HRTEM, and XPS studies conrmed Pt-SnO2 heteroaggregate nanostructures, where SnO2 partially covered the Pt nanoparticle,surface.,2,、,In,comparison to the control Pt nanocatalysts, the Pt-SnO2 nanocatalysts exhibited higher catalytic activity and selectivity,.,3,、,the,enhanced catalytic performance of Pt-SnO2/Al2O3 originates from the cooperative PtSnO2 interaction inside the heteroaggregate,nanostructures.,Thanks for your listening!,