Patricia Haure

Catalytic wet peroxide oxidation of phenol solutions over CuO/CeO2 systems.

Three 5% CuO/CeO(2) catalysts were synthesized by sol-gel, precipitation and combustion methods, followed by incipient wetness impregnation with copper nitrate. The samples were characterized by XRD, TPR, BET and tested for the catalytic wet peroxide oxidation of a phenol solution (5 g/L). The reaction took place in a batch reactor at atmospheric pressure, in a temperature range of 60-80°C, during 4h. Phenol conversion, H(2)O(2) consumption, pH and chemical oxygen demand were determined. The reaction temperature and the catalyst loading did improve the phenol and the H(2)O(2) conversions. The effect on the selectivity towards complete mineralization was less marked, with levels among 60-70%. Stepwise addition of H(2)O(2) was also tested.

Thermal waves in the periodic operation of a trickle-bed reactor

Abstract Periodic operation of a trickle-bed reactor with on-off liquid flow using SO2 oxidation over activated carbon at 26°C as a test reaction yields a large increase in the oxidation rate. A portion of this increase is due to a higher bed temperature. The on-off liquid flow causes a rising temperature front which is followed by a falling front in the direction of the liquid flow. These moving waves have been observed and are predicted by a dynamic trickle-bed reactor model which allows for gas-liquid mass transfer, product inhibition of reaction and evaporation. This model was used without fitted constants, but gave nevertheless a satisfactory representation of the experimental data.

Prussian Blue onto Activated Carbon as a Catalyst for Heterogeneous Fenton-Like Processes

The main goal of this contribution is the development of a new heterogeneous Fenton-like oxidation system based on Prussian Blue supported over a commercially available granular activated carbon (GAC). The catalysts were prepared following basically three different approaches: (i) Prussian Blue (Fe3(Fe(CN)6)2) particles adsorbed onto the GAC by impregnation, (ii) Prussian Blue nanoparticles (PBNP) prepared ex-situ and adsorbed onto the GAC; and (iii) PBNP prepared in-situ onto the GAC. The catalysts were characterized by SEM, EDS, BET surface area and Fe content. Their performance in the catalytic wet peroxide oxidation of a model azo dye, Orange G, was tested in a batch lab-scale stirred reactor. Activity and stability runs were carried out and analyzed in terms of dye discoloration, Total Organic Carbon removal, UV-vis spectra and degree of iron leaching.

Effect of variables on the periodic operation of a trickle bed reactor

Publisher Summary Periodic operation of Trickle Bed Reactor (TBR) deliberately modifies the wetting condition of the catalytic bed, allowing creating dry areas. If properly controlled, it can benefit reactor performance, especially in gas-limited-liquid volatile reactions with important heat effects. In the dry cycles, reaction proceeds between the liquid holdup (internal and external) and the flowing gas. The liquid holdup diminishes with time, until is fully depleted. Gas flow rate and composition and liquid feed composition and temperature have an important effect on reactor performance during cycling.

“Soluble” vs. “insoluble” Prussian blue based catalysts: influence on Fenton-type treatment

The influence of the synthesis procedure of supported Prussian blue nanoparticles (PBNP) on their activity and stability as a Fenton-type catalyst is studied. Hence, two catalysts are synthesized by adsorbing onto a support of PBNP formed ex situ through the reaction between FeCl3 and K3Fe(CN)6 using H2O2 as reducing agent, and following different washing protocols. A third catalyst is prepared through a two-step impregnation process with FeCl3 and K4[Fe(CN)6] aqueous solutions. The catalysts are tested in the orange G Fenton-type oxidation. The fresh and used catalysts are characterized by BET surface area, SEM, EDS, TEM, Mossbauer spectroscopy, total iron content and UV-vis spectrophotometry. It is demonstrated that under the synthesis conditions employed, the “insoluble” form of Prussian blue is promoted in the ex situ procedure, whereas the two-step impregnation process leads to the “soluble” Prussian blue formation. The washing of the just-prepared catalysts at the reaction temperature helps in eliminating the unreacted species. Those catalysts based on “insoluble” Prussian blue nanoparticles exhibit better behaviour in terms of stability. Significant removals are attained (100% azo dye, 60% TOC), at pH = 3, 343 K after thirteen successive cycles of 300 min. The best catalyst displays the smallest amount of total “free” Fe leached without releasing PBNP, ferrocyanide or ferricyanide ions into the reaction media. Reversible adsorption–desorption of organic intermediates avoids the loss of activity due to blockage of sites and/or pores.