Honeycomb monolithic design to enhance the performance of Ni-based catalysts for dry reforming of methane

Supported Ni catalysts (4,5% wt%) using a Ce-Zr oxide (18/82 molar ratio and a ceria rich surface) depicting advanced redox properties, were deposited by washcoating over cordierite honeycombs (230 and 400 cpsi). FIB-STEM unveiled nanostructure details otherwise undistinguishable by conventional techniques. The catalytic performance was evaluated in the dry reforming of methane al 700-900 degree C, using a CH4:CO2 1:1 feddstock, and exploring high Weight Hourly Space Velocity (115-346 L.g-1.h-1). The structured catalyts exhibited better performance than the corresponding powers, reaching values close to rhermodynamics limits for booth reactants conversion and H2/CO ratio, from 750 dgree C, and no deactivation was observed in prolongued experiments (24-48 h). This was related to both the high catalytic efficiency after being deposited with low loading on the cordierite and the intrinsic advantages of the monolithic reactor, like preventing from the kinetic control that operates in powdered samples under high WHSV or limiting the deactivation.Comment: 10 pages, 8 figures, 3 tables, 61 reference

Ultrathin Washcoat and Very Low Loading Monolithic Catalyst with Outstanding Activity and Stability in Dry Reforming of Methane

A Ni/CeO2/ZrO2 catalyst with improved redox properties has been washcoated onto a honeycomb cordierite monolith in the form of a nonconventional alumina-catalyst layer, just a few nanometers thick. In spite of the very low active phase loading, the monolith depicts outstanding performance in dry reforming of methane, both in terms of activity, with values reaching the thermodynamic limit already at 750 degrees C, even under extreme Weight Hourly Space Velocities (WHSV 115-346 Lg(F -1)h(-1)), as well as in terms of stability during prolonged Time on Stream (TOS 24-48 h)

Honeycomb monolithic design to enhance the performance of Ni-based catalysts for dry reforming of methane

Supported Ni catalysts (4.5 wt%) using a Ce-Zr oxide (18/82 molar ratio and a ceria-rich surface) depicting advanced redox properties, were deposited by washcoating over cordierite honeycombs (230 and 400 cpsi). FIB-STEM unveiled nanostructure details otherwise undistinguishable by conventional techniques. The catalytic performance was evaluated in the dry reforming of methane at 700-900 ºC, using a CH4:CO2 1:1 feedstock, and exploring high Weight Hourly Space Velocity (115-346 L g-1 h-1). The structured catalysts exhibited better performance than the corresponding powders, reaching values close to thermodynamic limits for both reactants conversion and H2/CO ratio, from 750 ºC, and no deactivation was observed in prolonged experiments (24-48 hours). This was related to both the high catalyst efficiency after being deposited with low loading on the cordierite and the intrinsic advantages of the monolithic reactor, like preventing from the kinetic control that operates in powdered samples under high WHSV or limiting the deactivation.The authors thank the financial support by the Ministry of Economy and Competitiveness of Spain/FEDER Program of the EU (Project MAT2017-87579-R), and the Junta de Andalucía (Groups FQM-110 and FQM-334). We also acknowledge the Cadiz University SC-ICyT for using its facilities for the ICP-AES, XRD, XRF and SEM-EDX measurements, and the Seville University CITIUS for the FIB-(S)TEM studies.Artículo científico de 10 pgs. Publicado el 1 de enero de 2022 y cumplidos dos años desde dicha fecha, se puede incluir el fichero con la versión remitida a publicar en el repositorio institucional RODIN

3D-printing of metallic honeycomb monoliths as a doorway to a new generation of catalytic devices: the Ni-based catalysts in methane dry reforming showcase

Stainless-steel honeycomb monoliths (square cell-shape/230 cpsi cylinders) were 3D-printed and used as support of a Ni/CeO2-ZrO2 powder deposited by washcoating. The resulting catalysts were characterized by XRF, SEM-EDX and H-2-TPR, and tested in the dry reforming of methane reaction. In the 750-900 degrees C range, they showed competitive conversions (45-95%) and H-2/CO ratio (0.84-0.94) compared to cordierite honeycombs with same catalyst loading and geometric characteristics, but did not require activation time thanks to better heat transfer. Both structured catalysts were stable in prolonged TOS experiments. The bare metallic monoliths exhibited significant activity at 900 degrees C due to their intrinsic nickel content

Removal of tiemonium methylsulfate, from aqueous solutions using activated carbon prepared from date stones

International audienceThe retention of a pharmaceutical compound, tiemonium methylsulfate (TIM), from aqueous solutions by adsorption onto activated carbon prepared from date stones (AC–DS) was investigated. Physical and chemical characteristics of this material were also determined. Results showed that pH 8 was optimal for TIM adsorption. Among the kinetic models considered, the pseudo-second-order model was the most appropriate to describe experimental data. Regarding adsorption isotherms, it was shown that the Sips model accurately describe the sorption of TIM onto AC–DS with a correlation factor R2 > 0.98. The adsorption capacity of AC–DS was found to be 42.2 mg g−1 at 10°C and 60.5 mg g−1 at 25°C, confirming its efficiency for the removal of this compound from aqueous solutions. The values of ΔG0 and ΔH0 confirmed that the adsorption of TIM onto AC–DS was spontaneous and endothermic in nature and hence more effective at high temperatures. An irregular increase in the randomness was suggested at the AC–DS solution interface during the adsorption process for positive values of ΔS0

Impact of -Cation Exchange Resin Composite on the Removal of Ethyl Violet

International audienceAdsorption capacity and photocatalytic performance of a mixture of and a cation exchange resin were assessed by measuring the removal of the cationic dye ethyl violet (EV) from water. Highest adsorption of EV was achieved at pH 3 due to the increase in number of positive charges of the EV molecule. However, adsorption decreased at higher pH. The adsorption kinetics at pH 3 could be accurately described by means of a pseudo-second order kinetic model. Experimental adsorption equilibrium data at pH 3 fitted the Langmuir model more accurately than the Sips and Freundlich models. Photocatalysis experiments indicated that the EV elimination was higher with the mixture of cation exchange resin and than with pure . The description of experimental photocatalysis data by means of the Langmuir-Hinshelwood model was improved by introducing a power parameter in the original model. From the modified Langmuir-Hinshelwood model, it could be derived that the addition of increasing resin concentrations to a constant concentration enhanced the photocatalytic rate constant; however, UV light penetration in the solution was impeded beyond a given resin amount. Pseudo-first-order kinetics showed poor fit of experimental photocatalysis data except for low EV concentration ( mg/L) at high resin dosage. A synergistic effect between adsorption and photocatalysis was seen upon combining the . This composite was more efficient for the removal of the dye than the use of alone

Removal of tiemonium methylsulfate, from aqueous solutions using activated carbon prepared from date stones

International audienceThe retention of a pharmaceutical compound, tiemonium methylsulfate (TIM), from aqueous solutions by adsorption onto activated carbon prepared from date stones (AC–DS) was investigated. Physical and chemical characteristics of this material were also determined. Results showed that pH 8 was optimal for TIM adsorption. Among the kinetic models considered, the pseudo-second-order model was the most appropriate to describe experimental data. Regarding adsorption isotherms, it was shown that the Sips model accurately describe the sorption of TIM onto AC–DS with a correlation factor R2 > 0.98. The adsorption capacity of AC–DS was found to be 42.2 mg g−1 at 10°C and 60.5 mg g−1 at 25°C, confirming its efficiency for the removal of this compound from aqueous solutions. The values of ΔG0 and ΔH0 confirmed that the adsorption of TIM onto AC–DS was spontaneous and endothermic in nature and hence more effective at high temperatures. An irregular increase in the randomness was suggested at the AC–DS solution interface during the adsorption process for positive values of ΔS0