Highly Dispersed PdNPs/α-Al2O3 Catalyst for the Selective Hydrogenation of Acetylene Prepared with Monodispersed Pd Nanoparticles

Abstract

Pd nanoparticles (PdNPs) stabilized by methyl cellulose (MC) were synthesized in an aqueous solution, which are monodispersed nanoparticles. PdNPs/α-Al 2 O 3 catalyst was prepared with monodispersed PdNPs and showed better catalytic performance than Pd/α-Al 2 O 3 catalyst prepared by the incipient wetness impregnation method using Pd(NO 3) 2 as a precursor. The catalysts were characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), X-ray powder diffraction (XRD) and inductively coupled plasma mass spectrometry (ICP-MS). It was found that monodispersed PdNPs were spherical or elliptical nanoparticles with exposed (111) and (100) facets, and the PdNPs/α-Al 2 O 3 catalyst showed a more concentrated distribution of Pd particles on the surface of α-Al 2 O 3 support than the Pd/α-Al 2 O 3 catalyst. The preparation method achieved the highly dispersed PdNPs/α-Al 2 O 3 catalyst with smaller Pd particle size and decreased the aggregation of Pd active sites, which was responsible for higher acetylene conversion and ethylene selectivity.

Photoinduced Strong Metal–Support Interaction for Enhanced Catalysis

“…UV irradiation exhibited no significant change in morphology, and a slightly decreased surface area was detected (Figures S5–S7 and SC-2). High-resolution transmission electron microscopy (HR-TEM) images of Pd/TiO 2 showed bare Pd NPs located at the edge and the middle area of the TiO 2 support (Figure A), with lattice fringes of 0.36 nm for (101) TiO 2 and 0.23 nm for (111) Pd NPs. ,− For Pd/TiO 2 –SMSI-30 min obtained after UV irradiation (Figures B and S8), the TiO 2 overlayer was formed surrounding the Pd NPs at the edge of the support, together with a partially covered (101) TiO 2 layer with lattice fringes of 0.36 nm on the edge sites of Pd NPs. In addition, the Pd NPs in the middle area of the support were covered by a (101) TiO 2 layer with lattice fringes of 0.36 nm (partially). ,− The lattice fringes of the Pd NPs were blurred, completely different from those in Pd/TiO 2 precursor.…”

“…High-resolution transmission electron microscopy (HR-TEM) images of Pd/TiO 2 showed bare Pd NPs located at the edge and the middle area of the TiO 2 support (Figure A), with lattice fringes of 0.36 nm for (101) TiO 2 and 0.23 nm for (111) Pd NPs. ,− For Pd/TiO 2 –SMSI-30 min obtained after UV irradiation (Figures B and S8), the TiO 2 overlayer was formed surrounding the Pd NPs at the edge of the support, together with a partially covered (101) TiO 2 layer with lattice fringes of 0.36 nm on the edge sites of Pd NPs. In addition, the Pd NPs in the middle area of the support were covered by a (101) TiO 2 layer with lattice fringes of 0.36 nm (partially). ,− The lattice fringes of the Pd NPs were blurred, completely different from those in Pd/TiO 2 precursor. The electron energy loss spectroscopy (EELS) intensity and composition mapping of Pd, O, and Ti further demonstrated the formation of the TiO x overlayer, with slightly reduced Ti being detected on the top of the Pd NPs in the EELS spectrum of Pd/TiO 2 –SMSI-30 min but absent in Pd/TiO 2 precursor (Figures C,D, S9, and S10).…”

Base‐free synthesis of bio‐derived 2,5‐furandicarboxylic acid using SBA‐15 supported heteropoly acids in ionic liquids

“…Figure 2 shows the XRD spectra of supported HPM catalysts. There are generally two kinds of crystals of Al 2 O 3 , while several peaks at 2θ of 35∼45° and 50∼60° disappeared and only α‐ Al 2 O 3 remained and increased [16] . In addition, new peaks presented at 2θ of 8.0°, 9.1° and 15.9°, which could be attributed to MoO 3 [17] .…”

“…There are generally two kinds of crystals of Al 2 O 3 , while several peaks at 2θ of 35 ∼ 45°and 50 ∼ 60°disappeared and only α-Al 2 O 3 remained and increased. [16] In addition, new peaks presented at 2θ of 8.0°, 9.1°and 15.9°, which could be attributed to MoO 3 . [17] This reveals that the supported HPM was unstable, and that MoO 3 was leached.…”

Improvement Effect of Ni to Pd-Ni/SBA-15 Catalyst for Selective Hydrogenation of Cinnamaldehyde to Hydrocinnamaldehyde

“…As illustrated in Figure 5A, the XPS in the range of 333-345 eV was ascribed to the Pd3d region. The Pd3d5/2 and Pd3d3/2 peaks at higher binding energies (337.6 and 342.7 eV) were described to the Pd 2+ species and the Pd3d5/2 and Pd3d3/2 peaks at lower binding energies (335.0 and 340.6 eV) were attributed to the Pd 0 (metallic palladium) [30,42]. However, there was a shift of 0.1-0.5 eV towards high binding energy for three 0.2%Pd-x%Ni/SBA-15 (b-d) In order to prove the role of Ni, the TEM images of the 0.9%Pd/SBA-15 and 0.9%Pd-1.2%Ni/SBA-15 catalysts with high Pd content were also measured ( Figure S3).…”