A Raman and ultraviolet diffuse reflectance spectroscopic investigation of silica-supported molybdenum oxide

Solid-Acid Catalyzed Continuous-Flow Aminolysis of Epoxides

We report a solid-acid catalyzed aminolysis of epoxides under continuous-flow conditions. A titania-zirconia supported molybdenum oxide catalyst demonstrated exceptional substrate compatibility, enabling the synthesis of β-amino alcohols in excellent yields with high catalyst durability. Characterization of the catalyst revealed the crucial role of the titania-zirconia ratio in optimizing its performance. Furthermore, this method was applied to the efficient, sequential-flow synthesis of a rivaroxaban intermediate (an oral anticoagulant and the first direct factor Xa inhibitor), combining a hydrogenation step with the aminolysis reaction without the need for intermediate isolation.

Using molybdenum carbiding to induce digestion of carbon in H2O2: A sustainable approach to eliminate radioactivity for hazardous graphite waste inherited from nuclear enterprise

To properly manage nuclear wastes is critical to sustainable utilization of nuclear power and environment health. Here, we show an innovative carbiding strategy for sustainable management of radioactive graphite through digestion of carbon in H₂O₂. The combined action of intermolecular oxidation of graphite by MoO₃ and molybdenum carbiding demonstrates success in gasifying graphite and sequestrating uranium for a simulated uranium-contaminated graphite waste. The carbiding process plays a triple role: (1) converting graphite into atomic carbon digestible in H₂O₂, (2) generating oxalic ligands in the presence of H₂O₂ to favor U-precipitation, and (3) delivering oxalic ligands to coordinate to Mo^VI-oxo anionic species to improve sample batching capacity. We demonstrate > 99% of uranium to be sequestrated for the simulated waste with graphite matrix completely gasifying while no detectable U-migration occurred during operation. This method has further been extended to removal of surface carbon layers for graphite monolith and thus can be used to decontaminate monolithic graphite waste with emission of a minimal amount of secondary waste. We believe this work not only provides a sustainable approach to tackle the managing issue of heavily metal contaminated graphite waste, but also indicates a promising methodology toward surface decontamination for irradiated graphite in general.

Probing Molybdenum Active Sites during In Situ Photoreduction of the Mo6+/SiO2 Catalyst

The photoreduction of the Mo⁶⁺/SiO₂ system with CO was investigated in situ, employing a recently developed experimental setup allowing for the acquisition of transmission FT-IR spectra under simultaneous UV irradiation. Carbon monoxide, besides acting as a reducing agent in such processes, is also a useful probe molecule able to detect coordinatively unsaturated sites exposed on the surface. The unprecedented quality of the spectroscopic data, obtained as a function of the reduction time, allowed us to better rationalize the different mechanisms previously proposed for the photoreduction process. These results, coupled with UV-Vis spectroscopic data, shed light on the oxidation state and surface structure of supported molybdenum species, which are key active sites for several important reactions, such as selective oxidation, polymerization, hydrodesulfurization, epoxidation and olefin metathesis.

Study on the selective oxidation of methane over highly dispersed molybdenum-incorporated KIT-6 catalysts

The isolated MoO_x species contribute to the highly selective formation of formaldehyde.

Propylene synthesis via isomerization–metathesis of 1-hexene and FCC olefins

Highly efficient conversion of 1-hexene and FCC mixture to propylene via isomerization–metathesis (ISOMET) catalyzed by a HBEA–MoOx/Al2O3 system.

A chemical titration method for quantification of carbenes in Mo- or W-containing catalysts for metathesis of ethylene with 2-butenes: verification and application potential

We introduce and experimentally validate a simple titration method for quantifying the number of carbenes acting as active sites in the metathesis of ethylene with 2-butenes over Mo- or W-containing catalysts.

Silica-supported isolated molybdenum di-oxo species: formation and activation with organosilicon agent for olefin metathesis

A well-defined silica-supported molybdenum dioxo species, (SiO)₂Mo(O)₂, prepared via Surface Organometallic Chemistry, is highly active in metathesis upon reaction with organosilicon reducing agent.

Effect of 2,6-Bis-(1-hydroxy-1,1-diphenyl-methyl) Pyridine as Organic Additive in Sulfide NiMoP/γ-Al₂O₃ Catalyst for Hydrodesulfurization of Straight-Run Gas Oil

The effect of 2,6-bis-(1-hydroxy-1,1-diphenyl-methyl) pyridine (BDPHP) in the preparation of NiMoP/γ-Al₂O₃ catalysts have been investigated in the hydrodesulfurization (HDS) of straight-run gas oil. The γ-Al₂O₃ support was modified by surface impregnation of a solution of BDPHP to afford BDPHP/Ni molar ratios (0.5 and 1.0) in the final composition. The highest activity for NiMoP materials was found when the molar ratio of BDPHP/Ni was of 0.5. X-ray diffraction (XRD) results revealed that NiMoP (0.5) showed better dispersion of MoO₃ than the NiMoP (1.0). Fourier transform infrared spectroscopy (FT-IR) results indicated that the organic additive interacts with the γ-Al₂O₃ surface and therefore discards the presence of Mo or Ni complexes. Raman spectroscopy suggested a high Raman ratio for the NiMoP (0.5) sample. The increment of the Mo=O species is related to a major availability of Mo species in the formation of MoS₂. The temperature programmed reduction (TPR) results showed that the NiMoP (0.5) displayed moderate metal–support interaction. Likewise, X-ray photoelectron spectroscopy (XPS) exhibited higher sulfurization degree for NiMoP (0.5) compared with NiMoP (1.0). The increment of the MoO₃ dispersion, the moderate metal–support interaction, the increase of sulfurization degree and the increment of Mo=O species provoked by the BDPHP incorporation resulted in a higher gas oil HDS activity.

MoOx–pyridine organic–inorganic hybrid wires as a reusable and highly selective catalyst for the oxidation of alcohols: a comparison study between reaction-controlled phase-transfer catalysis and heterogeneous catalysis

The different catalytic behaviors of Mo₃O₁₀(C₅H₆N)₂·H₂O wires (MoO_x–pyridine) in the selective oxidation of alcohols by means of molecular oxygen (O₂) and hydrogen peroxide (H₂O₂) as green oxidants were investigated.

Nickel and molybdenum containing mesoporous catalysts for ethylene oligomerization and metathesis

Ethylene is converted into propylene by one-pot cascade reactions over catalysts prepared using a commercial mesoporous non-ordered silica as a support.

Synthesis of aluminum-modified 3D mesoporous TUD-1 materials and their hydrotreating performance of FCC diesel

In this paper, alumina modified TUD-1 were synthesized. The related catalysts exhibited higher HDS and HDN activities than the catalyst over Al₂O₃. Therefore, TUD-1 is a promising candidate of catalyst additives for the industrial application.

Molybdenum oxide/γ-alumina: an efficient solid acid catalyst for the synthesis of nopol by Prins reaction

Prins condensation of β-pinene with paraformaldehyde was carried out over MoO_x/γ-Al₂O₃ catalyst in liquid phase.