Browsing by Author "Dafinov, Anton"

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Development and optimization of catalytic membrane reactors for wastewater treatments
(Universitat Rovira I Virgili, 2016-02-26) Pinos Vélez, Verónica Patricia; Dafinov, Anton; Medina Cabello, Francisco
Different catalytic membrane reactors (CMRs) were obtained from hollow fiber membranes corundum and palladium nanoparticles obtained by different methods: Incipient wetness impregnation , sputtering , microemulsion and copper alloy by the method of the polyol. The CMRs were tested in aqueous medium, ambient pressure and ambient temperature or 60C for the in situ generation of hydrogen peroxide, oxidation and hydrogenation of phenol and ibuprofen and reduction of Cr(VI). The catalytic CMR acted as interface for the reactions between hydrogen with oxygen or organic or inorganic compound. Only the CMRs with palladium by impregnation were actives and stabilites during the tests. This behavior occurred thanks to the presence of clusters and single atoms of palladium. The lack of activity of the other kind of palladium catalysts were due to the formation of palladium hydride in the reaction conditions.
Insights into palladium deactivation during advanced oxidation processes
(2022) Medina Cabello, Francesc; Dafinov, Anton; Pinos Vélez, Verónica Patricia; Osegueda Chicas, Oscar; Crivoi, Dana Georgiana; Llorca, Jordi; García García, Francisco Javier; García Álvarez, Mayra
A key step in creating efficient and long-lasting catalysts is understanding their deactivation mechanism(s). On this basis, the behavior of a series of Pd/corundum materials during several hydrogen adsorption/desorption cycles was studied using temperature-programmed desorption coupled with mass spectrometry and aberration-corrected transmission electron microscopy. The materials, prepared by impregnation and by sputtering, presented uniform well-dispersed Pd nanoparticles. In addition, single atoms and small clusters of Pd were only detected in the materials prepared by impregnation. Upon exposure to hydrogen, the Pd nanoparticles smaller than 2 nm and the single atoms did not present any change, while the larger ones presented a core-shell morphology, where the core was Pd and the shell was PdHx. The results suggest that the long-term activity of the materials prepared by impregnation can be attributed solely to the presence of small clusters and single atoms of Pd.
Preparation and characterization of catalytic membrane reactors
(Universidad de Cuenca, 2018) Pinos, Verónica; Medina, Francesc; Dafinov, Anton
Catalytic Membrane Reactors, CMR, are well known because of their versatility to develop various industrial processes. This versatility lies in CMR’s ability to run many functions in a single device. These functions can be filtration, dosage and catalysis. This work proposes four ways to prepare CMRs in interface mode to be tested in environmental remediation. For the preparation of Catalytic Membrane Reactors, commercial Hollow Fiber Membranes made of corundum were used. Palladium, as the main active phase, was synthesized by different methods such as impregnation, sputtering and microemulsion. Moreover, copper palladium alloy nanoparticles were obtained by the polyol route. The reactors obtained were tested in aqueous medium, at atmospheric pressure and low reaction temperatures (< 60°C) in the following reactions: in situ generation of hydrogen peroxide and phenol oxidation. The best results were achieved with the CMR with palladium prepared by impregnation. The others CMRs showed fast deactivation in all tests.
Preparation and characterization of catalytic membrane reactors
(2018) Pinos Vélez, Verónica Patricia; Medina, Francesc; Dafinov, Anton
Catalytic Membrane Reactors, CMR, are well known because of their versatility to develop various industrial processes. This versatility lies in CMR’s ability to run many functions in a single device. These functions can be filtration, dosage and catalysis. This work proposes four ways to prepare CMRs in interface mode to be tested in environmental remediation. For the preparation of Catalytic Membrane Reactors, commercial Hollow Fiber Membranes made of corundum were used. Palladium, as the main active phase, was synthesized by different methods such as impregnation, sputtering and microemulsion. Moreover, copper palladium alloy nanoparticles were obtained by the polyol route. The reactors obtained were tested in aqueous medium, at atmospheric pressure and low reaction temperatures (< 60°C) in the following reactions: in situ generation of hydrogen peroxide and phenol oxidation. The best results were achieved with the CMR with palladium prepared by impregnation. The others CMRs showed fast deactivation in all tests.