Phenylacetylene hydrogenation coupled with benzyl alcohol dehydrogenation over Cu/CeO2: A consideration of Cu oxidation state

Active Sites and Interfacial Reducibility of CuxO/CeO2 Catalysts Induced by Reducing Media and O2/H2 Activation

“…The average crystallite sizes of CeO 2 were estimated using Scherrerʼs equation via the (111) crystal face of CeO 2 (Table ). The increase of average crystallite sizes is apparent by decreasing the molar ratio of Cu/N 2 H 4 ·H 2 O in the preparation of Cu x O, combined with XPS characterization, revealing that the reduction degree of copper species has an impact on the crystallinity of CeO 2 . , In contrast with the CeO 2 support, the cell parameter and d -spacing of CeO 2 for all the CuCe-1, CuCe-2, and CuCe-3 decrease via the Cu ion diffusion into the CeO 2 surface lattice to substitute Ce sites. The redistribution of electrons occurs between Cu and the surface oxygen, which might weaken the adjacent Ce–O bond strength to distort the configuration of the surface CeO 2 (Figure D,B), forming the Cu–O–Ce bonds at the surface. , In addition, the N 2 adsorption–desorption analysis (Figure C) shows that the physisorption isotherms are type IV ones, suggesting that the catalysts have a mesoporous structure (Figure D). , The Brunauer–Emmett–Teller (BET) surface areas of the as-synthesized samples are in the range 66–101 m 2 g –1 (Table ).…”

“…The increase of average crystallite sizes is apparent by decreasing the molar ratio of Cu/N 2 H 4 •H 2 O in the preparation of Cu x O, combined with XPS characterization, revealing that the reduction degree of copper species has an impact on the crystallinity of CeO 2 . 47,53 In contrast with the CeO 2 support, the cell parameter and d-spacing of CeO 2 for all the CuCe-1, CuCe-2, and CuCe-3 decrease via the Cu ion diffusion into the CeO 2 surface lattice to substitute Ce sites. The redistribution of electrons occurs between Cu and the surface oxygen, which might weaken the adjacent Ce−O bond strength to distort the configuration of the surface CeO 2 (Figure 3D,B), forming the Cu−O−Ce bonds at the surface.…”

“…25,41 The width and intensity of the main diffraction peaks are sensitive to the nanoparticle size. 47 The average crystallite sizes of CeO 2 were estimated using Scherrerʼs equation via the (111) crystal face of CeO 2 (Table 2). The increase of average crystallite sizes is apparent by decreasing the molar ratio of Cu/N 2 H 4 •H 2 O in the preparation of Cu x O, combined with XPS characterization, revealing that the reduction degree of copper species has an impact on the crystallinity of CeO 2 .…”

“…The elemental composition and surface chemistry of the as-prepared catalysts were examined by XPS and Cu LMM Auger characterization. As shown in Figure A, the Cu 2p core-level spectra comprise the Cu 2p 1/2 and Cu 2p 3/2 peaks along with a broad satellite peak in the range of 938.0 – 950.0 eV. ,− The peaks centered at 934.3 eV and the corresponding satellite peaks are assigned to Cu 2+ , and the peaks located at 932.6 eV are attributed to the reduced copper species (Cu 0 or Cu + ). Combined with Cu LMM Auger spectra (Figure B), the percentages of Cu 0 , Cu + , and Cu 2+ on the surface of the catalysts were determined, as shown in Table and Figure C.…”

“…Figure B displays the (111) crystal plane of face-centered cubic Cu as well as the (111) and (200) facets of cubic-fluorite CeO 2 . For the other three samples, no diffraction peak characteristic of copper species is observed, suggesting that the copper species may exist in a highly dispersed state or an amorphous form on the surface of CeO 2 supports. , The width and intensity of the main diffraction peaks are sensitive to the nanoparticle size . The average crystallite sizes of CeO 2 were estimated using Scherrerʼs equation via the (111) crystal face of CeO 2 (Table ).…”