Fe- and Mn-modified SO42−/ZrO2 conjoined O2–Ac2O as a composite catalytic system for highly selective nitration of 1-nitronaphthalene with NO2 to valuable 1,5-dinitronaphthalene

NO2 as benign nitrating agent and Fe–Mn bimetallic modified SZ as catalyst replaced traditional nitric–sulfuric mixed acid systems for 1-NN nitration. The synergism of Fe1.5Mn0.5–SZ and O2–Ac2O significantly improved the selectivity to 1,5-DNN.

Glucose Oxidase Immobilized on Magnetic Zirconia: Controlling Catalytic Performance and Stability

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 ZrO₂ 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.

Nano-sized mesoporous phosphated tin oxide as an efficient solid acid catalyst

Herein, we prepared a mesoporous tin oxide catalyst (mSnO₂) activated with phosphate species by the adsorption of phosphate ions from a phosphoric acid solution onto tin oxyhydroxide (Sn(OH)₄) surface.

Controlling the redox properties of nickel in NiO/ZrO2 catalysts synthesized by sol–gel

NiO–ZrO₂ interaction affects the electronic properties and activity of NiO.

One-Pot Isomerization of n-Alkanes by Super Acidic Solids: Sulfated Aluminum-Zirconium Binary Oxides

Super acidic nanostructured sulfated aluminum-zirconium binary oxides in mole ratios of Zr4+: Al3+ as 2:1 (SAZ-1), 1:1 (SAZ-2), 1:2(SAZ-3) and the reference catalyst super acidic sulfated zirconia (SZ) were synthesized by a precipitation method. Firstly, the catalytic performance of these four catalysts was evaluated during the isomerization of n-hexane to 2-methyl pentane and 3-methyl pentane, n-heptane and n-octane to their corresponding branched chain isomers at low temperature and pressure conditions (40°C and 1 atm). SAZ-1 performed the highest active and selective isomerization of n-hexane, n-heptane, and n-octane into their corresponding branched chain isomers. The catalytic activity of the reference catalyst SZ was the lowest among the four synthesized catalysts. TEM analysis applied to SAZ-1 and SZ indicated the presence of particle-bulks having average size of 20 nm; moreover, these materials presented an amorphous nature, having no particular surface morphology. XRD confirmed the amorphous structure of SAZ-1 and SZ as well as indicated their internal phase structure. FTIR generated ideas about different linkages and bond connectivities between atoms and groups in SAZ-1 and SZ. Ammonia-TPD of these two materials confirmed the higher super acidic nature of SAZ-1 and lower super acidic nature of SZ. Catalyst evaluation and characterization allowed to propose a reaction mechanism, elucidating a possible role of Brønsted and Lewis acid sites on the studied reaction-catalyst, being the former active sites the main factor leading to isomerization reaction. AFM and SEM pictures indicated the nature of the surface of the catalysts. Nevertheless, SEM analysis before and after the reaction displayed that catalyst morphology was modified and could influence the activity of the catalyst. The use of SAZ-1 is cost saving as well as energy saving.

One-step preparation of efficient and reusable SO4(2-)/ZrO(2)-based hybrid solid catalysts functionalized by alkyl-bridged organosilica moieties for biodiesel production

A series of mesoporous sulfated zirconia materials functionalized by alkyl-bridged organosilica moieties (SO(4)(2-)/ZrO(2)-SiO(2)(R) with various S/Si or Zr/Si molar ratios and R=CH(2)CH(2) or C(6)H(4)) were developed by a one-step co-condensation technique combined with hydrothermal treatment with the aid of a triblock copolymer surfactant (P123). The structures, morphologies, porosities, and acid properties of the materials were well characterized. Subsequently, the catalytic performances (activity and stability) of SO(4)(2-)/ZrO(2)-SiO(2)(R) were evaluated by the transesterification of both pure triglyceride (tripalmitin) and low-cost virgin plant oil (Eruca sativa Gars. oil) with methanol for biodiesel production under mild conditions (atmospheric pressure, 65 °C), and the enhanced catalytic activity with respect to alkyl-free sulfated zirconia was obtained. This excellent catalytic activity was explained in terms of the inherent Brønsted acidity, well-defined mesoporosity, and increased hydrophobicity of the as-prepared, hybrid, solid acid catalyst.