《催化剂PPT》由会员分享，可在线阅读，更多相关《催化剂PPT（18页珍藏版）》请在金锄头文库上搜索。
1、Design of Highly Efficient Pt-SnO2 Hydrogenation Nanocatalysts using PtSn CoreShell NanoparticlesCharacterizationsynthesis 1.2.CharacterizationXRD 01TEM 02XPS 03TPO 04DRIFT-IR 05XRD patterns showing (a) Pt NPs, (b) PtSn NPs, and (c) Pt-SnO2 NPs obtained by calcination of PtSn NPs at 500 for 3 h.As s
2、hown 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 pattern
3、s of individual Pt, assynthesized PtSn, and Pt-SnO2 NPs obtained by calcination of PtSn NPsTEM studies of Pt NPs, PtSn NPs, Pt/Al2O3, and PtSnO2/Al2O3 Small percentages of Sn+ and Pt2+ are observed for PtSn NPs and Pt2+、Pt4+ are observed for Pt-SnO2 NPs presumably due to the exposure of NPs to air.T
4、he binding energies at 486.6/494.9 eV in Figure b can be assigned to 3d5/2/3d3/2 of Sn4+, which is consistent with the XPS database of SnO2 and their XRD patterns.XPS spectra showing (a) as-synthesized PtSn and (b) Pt-SnO2The higher Sn/Pt ratio for PtSn by XPS is consistent with PtSn coreshell struc
5、turesThe Pt/oxidized Pt ratio of 27.68/72.32 for Pt-SnO2 indicates that more surface Pt atoms are oxidized by calcinationSn/Pt ratio of 2.79/ 1.00 by XPS suggests heteroaggregate nanostructures with a distribution of SnO2 on Pt surfaces. TPO study of PtSn/Al2O3further confirms the complete oxidation
6、 of Sn of PtSn below 300DRIFT-IR spectra with CO probes Only CO bands on Pt are observed, since CO is not adsorbed on tinlinear CO on Pt step and kink sitesthe surfaces mainly consist of Sn and the majority of Pt is in the coreslinear CO on Pt step and kink siteslinear CO on Pt terrace sitesCatalyti
7、c Performance Pt-SnO2/Al2O3 with a Pt/Sn ratio of 1/1 has the highest catalytic activity and excellent catalytic selectivity Catalytic Performance Pt-SnO2/Al2O3 nanocatalysts had higher activity and selectivity than Pt/Al2O3 nanocatalysts, with the exception that the selectivity of catalytic m-CNB h
8、ydrogenation over Pt-SnO2/Al2O3 is lower than that over Pt/Al2O3. 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 selecti
9、vities 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 first five cycl
10、es, the catalytic activity of Pt-SnO2/Al2O3 was stable, and the catalytic selectivity slightly increased, suggesting a good structural stability of Pt-SnO2 heteroaggregate nanocatalyststheoretical calculations(using DET)the partial coverage of Pt (111) surfaces with SnO2 slightly promotes the H adso
11、rption 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 ratethe enhanced catalytic performance of Pt-SnO2/Al2O3 nanoc
12、atalysts originates from the cooperative interaction between Pt and SnO2 inside the heteroaggregate nanostructuresConclusion1、 DRIFT-IR with CO probes, HRTEM, and XPS studies confirmed 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!
