Search results for "PARTIAL OXIDATION"

Photocatalytic and photoelectrocatalytic H2 evolution combined with valuable furfural production

2023

In this work the photocatalytic (PC) and photoelectrocatalytic (PEC) reforming of furfuryl alcohol (FA) under environmental friendly conditions was investigated. Both H2 evolution and partial oxidation to furfuraldehyde were followed. For the first time TiO2 based photocatalysts were studied and the photocatalytic activity of home prepared photocatalysts was compared with that of commercial ones under both UVA and simulated solar irradiation. PEC tests were performed by using home prepared TiO2 nanotubes (TiO2 NTs) as photoanode and Pt free Ni foam as cathode to improve the Hydrogen Evolution Reaction (HER). Both the partial FA oxidation reaction rate and H2 evolution rate were normalized f…

A facile way to synthesize noble metal free TiO2 based catalysts for glycerol photoreforming

2023

In this work anaerobic heterogeneous photocatalytic solar/UV light reforming of glycerol in aqueous media was performed with Pt-photodeposition and noble metal free modified TiO2 photocatalysts prepared through ball milling, a very simple and cheap coupled catalyst preparation method. Different amounts of Cu2O or 3% CuO were loaded on TiO2 using ball milling and during each run glycerol conversion, hydrogen and CO2 formed in the gas phase and 1,3-dihydroxyacetone (DHA) and glyceraldehyde (GA) in the liquid phase were determined. The results were compared with the aim to verify the effectiveness of Cu2O in replacing Pt. Using noble metal free photocatalysts, 33% glycerol conversion, 10.3% an…

Mo-W-containing tetragonal tungsten bronzes through isomorphic substitution of molybdenum by tungsten

2010

Mixed metal oxides based in Mo(W)–Nb–V–Te with tetragonal tungsten bronze (TTB) structure have been synthesized by a hydrothermal method from aqueous solutions of the corresponding Keggin-type heteropolyacids and further heat-treatment in N2 at 700 ◦ C. The materials have been characterized by several physico-chemical techniques, i.e. XRD, Raman, FTIR, SEM-EDS, and TEM. This procedure allows controlling the chemical species to be distributed in the different interstices of the TTB skeleton, which is a key factor to regulate the catalytic properties of the final solid. In this sense, the isomorphic replacement of Mo by W results in lattice parameter and crystal morphology variation, although…

Cobalt in strontium titanate based perovskites: preparation, characterization and role in the photocatalytic propene partial oxidation

2016

Strontium titanate perovskite (SrTiO3) and analogous materials in which Y partially substitutes Sr have been prepared as basis to integrate Co in the structure. The Co inserrtion has been performed by wet impregnation or coprecipitation methods. The obtained powders have been physico-chemically characterized and tested as photocatalysts in the propene partial oxidation by using a solar simulating reactor. Correlation between photocatalytic performance and physicochemical characteristics of the different catalysts allows to assess a key role of local nanostructuring of CoOx sites on the selectivity and distribution of products.

Room Temperature Home Prepared TiO2 Rutile Used for Selective Photocatalytic Oxidation of Aromatic Alcohols to Aldehydes in Aqueous Medium

2009

Synthesis of vanillin in water by TiO2 photocatalysis

2012

Abstract The photoproduction of vanillin is studied in aqueous medium starting from trans-ferulic acid, isoeugenol, eugenol or vanillyl alcohol by using both commercial and home prepared TiO2 samples as photocatalysts and batch Pyrex photoreactors. The photo-oxidation at room temperature of these compounds produces vanillin with a selectivity ranging from 1.4 to 21 mol% with respect to the converted substrate. An investigation on the intermediates was performed in the case of trans-ferulic acid; for this substrate the most important intermediates were homovanillic acid, vanillyl mandelic acid, trans-caffeic acid, formic acid, acetic acid, and oxalic acid. The carbon mass balance, including …

Theoretical ab initio study of the vinylcarbene-CuO complex: application to last step of the propylene partial oxidation mechanism on Cu2O

1988

Abstract Using non-empirical pseudopotentials, we have performed a theoretical study on the last step of the propylene partial oxidation mechanism, the acrolein desorption from the catalyst surface. To represent the catalyst we have used a simplified model of a catalyst active site. We have study the C 3 H 4 CuO complex, analysing the dissociation process of the oxygenated complex from a metallic centre. The results indicate that this complex dissociates into cis - and trans -acrolein and a metal site, in a process without energetic barrier.

Anatase photocatalyst with supported low crystalline TiO2: The influence of amorphous phase on the activity

2018

Abstract In a previous study on commercial TiO2 nanoparticles (J. Soria et al.) we had shown that the superficial disordered layers influence their textural and reactivity features. In the present work we used well crystallized anatase particles (commercial TiO2, BDH) as support of different amounts of titania powders, prepared by TiCl4 hydrolysis and constituted by nanocrystals diluted into an amorphous matrix. The reactivity of these photocatalysts has been tested for the selective oxidation of 4-methoxybenzyl alcohol to aldehyde in aqueous suspension. The catalyst characteristics have been studied using adsorption-desorption isotherms, TEM, HRTEM, TGA, PL, DRIFT-IR, and 1H MAS-NMR spectr…

Selective oxidation of aromatic alcohols in the presence of C3N4 photocatalysts derived from the polycondensation of melamine, cyanuric and barbituri…

2021

AbstractA set of C3N4 samples has been prepared by using melamine, cyanuric acid and barbituric acid as the precursors. The materials were subjected both to physical and chemical characterization and were used as photocatalysts for the selective oxidation of aromatic alcohols in water suspension under UV and visible irradiation. The photoactivity of the materials versus the partial oxidation of four substituted benzyl alcohols was investigated. The type and position of the substituents in the aromatic molecule influenced conversion and selectivity to the corresponding aldehyde. The presence of barbituric and cyanuric acids in the preparation method has changed the graphitic-C3N4 structure, …

Partial oxidation of aromatic alcohols via TiO2 photocatalysis: the influence of substituent groups on the activity and selectivity

2012

Aromatic alcohols with substituent groups in different positions have been partially oxidised to the corresponding aldehydes in a photocatalytic system in order to investigate the influence of the substituents on reactivity and selectivity to aldehyde. To this aim benzyl alcohol, 2-methoxybenzyl alcohol, 3-methoxybenzyl alcohol, 4-methoxybenzyl alcohol, 2,4-dimethoxybenzyl alcohol, 4-hydroxybenzyl alcohol and 4-hydroxy-3-methoxybenzyl alcohol have been photocatalytically oxidised to their corresponding aldehydes in aqueous TiO2 suspensions under near-UV irradiation. Home-made and commercial rutile TiO2 samples were used as photocatalysts. The catalysts were characterized by XRD, BET, SEM, T…