Showing papers by "Asunción Quintanilla published in 2022"
TL;DR: In this article, the chemical kinetics of phenol hydroxylation by hydrogen peroxide (H2O2) to produce dihydroxybenzenes was studied using a 3D printed monolithic reactor.
16 citations
TL;DR: In this article , a kinetic model for formic acid (FA) decomposition over a commercial 10 wt% Pd/AC catalyst has been developed to describe the hydrogen production and to understand the deactivation mechanism.
Abstract: A kinetic model for formic acid (FA) decomposition over a commercial 10 wt% Pd/AC catalyst has been developed to describe the hydrogen production and to understand the deactivation mechanism. The kinetic data were obtained in a batch slurry reactor in absence of mass transfer limitation at: CFA,0 = 0.25–2 M, CCAT = 1 g L−1, T = 25–85 ºC and P = 1 atm. The catalyst stability was studied in successive cycles at different temperatures. Fresh, used and regenerated Pd/AC catalysts were deeply characterized to gain insight into the activity, selectivity and stability. H2 and CO2 were the only reaction products detected. The reaction follows a first order kinetic for FA while the activity shows exponential decay with the initial FA concentration and reaction temperature. This paper represents a step forward in the on-site hydrogen production technology by using FA as liquid organic hydrogen carrier.
6 citations
TL;DR: In this article, the feasibility of Fenton oxidation and Catalytic Wet Peroxide Oxidation (CWPO) at high temperature for the treatment of a complex cork-boiling wastewater (CBW) characterized by a high organic load (COD) and substantial content of phenolics.
5 citations
TL;DR: In this article , the performance of a stirring 3D Fe/Al2O3 monolithic reactor in batch operation applied to the liquid-phase hydroxylation of phenol by hydrogen peroxide (H2O2) was evaluated.
Abstract: The aim of this work is to evaluate the performance of the stirring 3D Fe/Al2O3 monolithic reactor in batch operation applied to the liquid-phase hydroxylation of phenol by hydrogen peroxide (H2O2). An experimental and numerical investigation was carried out at the following operating conditions: CPHENOL,0 = 0.33 M, CH2O2,0 = 0.33 M, T = 75–95 °C, P = 1 atm, ω = 200–500 rpm and WCAT ~ 1.1 g. The kinetic model described the consumption of the H2O2 by a zero-order power-law equation, while the phenol hydroxylation and catechol and hydroquinone production by Eley–Rideal model; the rate determining step was the reaction between the adsorbed H2O2, phenol in solution with two active sites involved. The 3D CFD model, coupling the conservation of mass, momentum and species together with the reaction kinetic equations, was experimentally validated. It demonstrated a laminar flow characterized by the presence of an annular zone located inside and surrounding the monoliths (u = 40–80 mm s−1) and a central vortex with very low velocities (u = 3.5–8 mm s−1). The simulation study showed the increasing phenol selectivity to dihydroxybenzenes by the reaction temperature, while the initial H2O2 concentration mainly affects the phenol conversion.
3 citations
TL;DR: In this article , two 3D Fe/SiC catalysts with a square cell geometry have been manufactured by Robocasting and studied in the catalytic phenol oxidation by hydrogen peroxide (H2O2) for the sustainable production of dihydroxybenzenes (DHBZ).
Abstract: The application of structured reactors provides a number of advantages in chemical processes. In this paper, two different three-dimensional (3D) Fe/SiC catalysts with a square cell geometry have been manufactured by Robocasting: monoliths (D = 14 and H = 15 mm) and meshes (D = 24 and H = 2 mm) and studied in the catalytic phenol oxidation by hydrogen peroxide (H2O2) for the sustainable production of dihydroxybenzenes (DHBZ). The fluid dynamics, catalytic performance, reaction rates, external mass transport limitation, and catalyst stability have been compared in three different reactors, monolithic fixed-bed reactor, multimesh fixed-bed reactor, and monolithic stirrer reactor, at selected operating conditions. The results show that the mechanical stirring of the 3D Fe/SiC monoliths avoids the external mass transfer limitation caused by the presence of oxygen bubbles in the channels (produced from the HOx· species in autoscavenging radical reactions). In addition, the backmixing has a positive effect on the efficient consumption of H2O2 but an adverse effect on the phenol selectivity to DHBZ since they are overoxidized to tar products at longer contact times. On the other hand, the wall porosity, and not the backmixing, affects the susceptibility of the 3D Fe/SiC catalyst to the Fe leaching, as occurs in the mesh structures. In conclusion, the monoliths operating under plug-flow and external mass transfer limitation in the monolithic fixed-bed reactor (MFB) provide an outstanding phenol selectivity to DHBZ and catalyst stability.