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A study was conducted on the chemisorbed carbon monoxide to examine the electronic and structural properties of highly disperse platinum-copper alloys supported on zeolite HZSM-5. X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy and transmission electron microscopy were used to examine the ion exchange between the zeolite and alloys. Results showed that the Fourier transform infrared spectroscopy of CO adsorption was the best tool for detecting alloy formation. Moreover, the absence of dipole-dipole interaction between the chemisorbed CO molecules allows for the determination of the dilution of the Pt surface with Cu.

The kinetics of the reduction of zeolite-hosted mononuclear Ti(VI)Ox species followed by ultraviolet/vis diffuse reflection spectroscopy were investigated. Results showed that the reduction kinetics can be fitted if a Ti site exists at the surface of the zeolite NaY crystals and two sites in the void structure. The reduction rates for various Ti(VI)Ox species were found to increase with an increase in the excitation energy of the O to Ti charge transfer and decreases with an increase in the nuclearity of TiO clusters.

The X-ray photoelectron spectroscopy (XPS) and ion scattering spectroscopy (IEE) are used to investigate the in situ calcinations and dehydration of supported vanadia catalysts. The XPS and ion scattering spectroscopy (ISS) surface studies confirms that the supported vanadium oxide catalysts consists of close-packed monolayers of surface vanadia species.

Here, we report the structures and properties of biocatalysts based on glucose oxidase (GOx) macromolecules immobilized on the mesoporous zirconia surface with or without magnetic iron oxide nanoparticles (IONPs) in zirconia pores. Properties of these biocatalysts were studied in oxidation of d-glucose to d-gluconic acid at a wide range of pH and temperatures. We demonstrate that the calcination temperature (300, 400, or 600 °C) of zirconia determines its structure, with crystalline materials obtained at 400 and 600 °C. This, in turn, influences the catalytic behavior of immobilized GOx, which was tentatively assigned to the preservation of GOx conformation on the crystalline support surface. IONPs significantly enhance the biocatalyst activity due to synergy with the enzyme. At the same time, neither support porosity nor acidity/basicity shows correlations with the properties of this biocatalyst. The highest relative activity of 98% (of native GOx) at a pH 6-7 and temperature of 40-45 °C was achieved for the biocatalyst based on ZrO 2 calcined at 600 °C and containing IONPs. This process is green as it is characterized by a high atom economy due to the formation of a single product with high selectivity and conversion and minimization of waste due to magnetic separation of the catalyst from an aqueous solution. These and an exceptional stability of this catalyst in 10 consecutive reactions (7% relative activity loss) make it favorable for practical applications., Competing Interests: The authors declare no competing financial interest., (Copyright © 2020 American Chemical Society.)

Here, we report on the development of novel Zn-, Zn-Cr-, and Zn-Cu-containing catalysts using magnetic silica (Fe 3 O 4 -SiO 2 ) as the support. Transmission electron microscopy, powder X-ray diffraction, and X-ray photoelectron spectroscopy (XPS) showed that the iron oxide nanoparticles are located in mesoporous silica pores and the magnetite (spinel) structure remains virtually unchanged despite the incorporation of Zn and Cr. According to XPS data, the Zn and Cr species are intermixed within the magnetite structure. In the case of the Zn-Cu-containing catalysts, a separate Cu 2 O phase was also observed along with the spinel structure. The catalytic activity of these catalysts was tested in methanol synthesis from syngas (CO + H 2 ). The catalytic experiments showed an improved catalytic performance of Zn- and Zn-Cr-containing magnetic silicas compared to that of the ZnO-SiO 2 catalyst. The best catalytic activity was obtained for the Zn-Cr-containing magnetic catalyst prepared with 1 wt % Zn and Cr each. X-ray absorption spectroscopy demonstrated the presence of oxygen vacancies near Fe and Zn in Zn-containing, and even more in Zn-Cr-containing, magnetic silica (including oxygen vacancies near Cr ions), revealing a correlation between the catalytic properties and oxygen vacancies. The easy magnetic recovery, robust synthetic procedure, and high catalytic activity make these catalysts promising for practical applications.