Synergetic effect between phases in MoVTe(Sb)NbO catalysts used for the oxidation of propane into acrylic acid

Results are reported concerning the synergetic effect obsd. in the oxidn. of propane to acrylic acid over the orthorhombic M1 and hexagonal M2 phases present in the most active and selective MoVTe(Sb)NbO catalysts. The pure phases and phase mixts. contg. either tellurium or antimony have been prepd. and individually tested as catalysts. The results obtained confirm that the phase responsible for the catalytic properties of the efficient catalysts is phase M1, and that M2 is poorly active. Mech. mixts. of the pure phases have also been prepd. and tested. All of the catalysts have been characterized before and after the catalytic reaction by X-ray diffraction, XPS, and high-resoln. electron microscopy with EDS analyses. Although the synergetic effect previously described (bifunctional catalysis with the oxidative dehydrogenation of propane mols. on the orthorhombic M1 phase and the subsequent oxidn. of propene on the hexagonal M2 phase) was obsd., another cause related to migration of tellurium from the M2 phase to the surface of the M1 phase was indicated. This migration should balance a loss of tellurium in the active phase occurring under the conditions of a catalytic test, but may also create new dehydrogenation sites for propene and/or anneal total oxidn. sites. The hexagonal M2 phase would thus play a role of tellurium reservoir for the active M1 phase. This effect was not reversible and concerned only the tellurium. Antimony, which is less volatile, should not be lost by the active phase. Furthermore, it was shown not to diffuse at the surface of the phases

Fourier transform infrared spectroscopic study of surface acidity by pyridine adsorption on the M1 active phase of the MoVTe(Sb)NbO catalysts used in propane oxidation

The adsorption of pyridine on the surface of the M1 active phase of the MoVTe(Sb)O catalysts was studied for the detn. of the Bronsted and Lewis acid sites. The results obtained showed medium Lewis and Bronsted acidity for antimony contg. phases and low Lewis and Bronsted acidity for tellurium ones. The incorporation of niobium in the M1 phases resulted in a decrease of both acidities. The samples characterized were tested as catalysts in the oxidn. of propane to acrylic acid. The results obtained allowed to propose correlations between the acidic properties and the catalytic selectivity

Study of new catalysts based on vanadium oxide supported on mesoporous silica for the partial oxidation of methane to formaldehyde: Catalytic properties and reaction mechanism

Vanadium oxide supported on mesoporous silica has been synthesized by a novel method and the resulting species tested as catalysts for the partial oxidation of methane to formaldehyde at atmospheric pressure. These catalysts appear to be very active and selective toward formaldehyde. Space–time yields superior to those of all known catalysts of the same type have been obtained. Kinetic parameters all tend to show that the same mechanism postulated for supported vanadium catalyst is taking place. The positive effect of water is also seen. The high performance has been attributed to the wide dispersion of vanadium-isolated species, which are known to be very active and selective, and to greatly superior silanol surface content than in other catalysts. The novel preparation method favors the formation of given isolated species that will be the most active and selective

Characteristics, treatment strategies, and outcome in cardiogenic shock complicating acute myocardial infarction: a contemporary Dutch cohort

Cardiogenic shock (CS) complicating acute myocardial infarction (AMI) is associated with high morbidity and mortality. Our study aimed to gain insights into patient characteristics, outcomes and treatment strategies in CS patients. Patients with CS who underwent percutaneous coronary intervention (PCI) between 2017 and 2021 were identified in a nationwide registry. Data on medical history, laboratory values, angiographic features and outcomes were retrospectively assessed. A total of 2328 patients with a mean age of 66 years and of whom 73% were male, were included. Mortality at 30 days was 39% for the entire cohort. Non-survivors presented with a lower mean blood pressure and increased heart rate, blood lactate and blood glucose levels (p-value for all Cardiolog