Structuration of Pd(2 wt %)/Fe−Al Oxide Catalysts on Ceramic and Metallic Monoliths: Physicochemical Characterization, Effect of the Nature of the Slurry, and Comparison with LaMnO₃Catalysts

Abstract

The main objective of this study has been twofold: (i) to investigate the effect of the nature of the slurry used to structurate a catalyst on monoliths; (ii) to study the influence of the nature of the monoliths on the physicochemical properties and on the catalytic activities in the combustion of methane. The slurry used in this work was made with an acidified solution of Pd(2 wt %)/Fe−Al oxide catalyst. This catalyst was prepared by the citrate method and deposited on ceramic and metallic monoliths according to a dip coating or an orbital stirring procedure. Both types of structured catalysts were studied using the following physicochemical techniques: specific surface area measurements (BET), scanning electron microscopy (SEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). The Pd(2 wt %)/Fe−Al oxide catalyst used for monolith coating does not undergo any textural or crystallinity modification during the deposition procedure. Catalytic activities obtained for powder and monolithic catalysts are compared. The surface of the support plays an important role in the structuration of catalysts. The amount of deposited catalyst has an influence on the catalytic activity. The amount of deposited catalysts depends on the nature of the monolith, on the coating technique, and on the nature of the slurry. Comparisons between structured Pd(2 wt %)/Fe−Al oxide and structured LaMnO3 on ceramic and metallic monoliths (previous work) were made to clarify the influence of the nature of the slurry on the amount of deposited catalysts. The amount of deposited catalysts on ceramic monolith using Pd(2 wt %)/Fe−Al oxide catalyst is lower than that deposited using LaMnO3. In the case of metallic monoliths, the difference is less significant. The influence of a diffusion limitation of the reaction rate in structured catalysts with Pd(2 wt %)/Fe−Al oxide seems to be less important than with LaMnO3. Higher catalytic activities were observed for Pd(2 wt %)/Fe−Al oxide on the ceramic monoliths at high temperature. Coating on the metallic monoliths led to a better activity at low temperature compared to the corresponding powder catalyst.

Complete Oxidation of Methane on NiO Nanoclusters Supported on CeO2 Nanorods through Synergistic Effect

“…Unlike gasoline-fueled engines, the engines of vehicles using natural gas or liquefied petroleum gas perform combustions of light hydrocarbons at relatively low temperatures, typically <600 °C. A catalyst that is highly active at temperatures below 600 °C for the complete transformation of methane into carbon dioxide is needed to remove the unburned methane in the exhaust line prior to release into the environment because CH 4 is a much stronger greenhouse gas than CO 2 . − The activation of methane and complete oxidation to CO 2 and H 2 O at temperatures lower than 600 °C require a highly active catalyst because CH 4 has the strongest C–H bond among hydrocarbons. ,− Supported Pt and Pd are active for complete oxidation of methane to CO 2 and H 2 O at a relatively low temperature. ,,− Due to the prohibitive price of Pt and Pd, it is necessary to find an alternative made of earth-abundant elements.…”

Metal–Support Interactions within a Dual-Site Pd/YMn2O5 Catalyst during CH4 Combustion

“…CH 4 is a cleaner alternative to other fossil fuels for delivering reliable and affordable energy and decreasing the emissions of noxious and/or greenhouse gases (GHGs) into the atmosphere. 1 According to the International Association of Natural Gas Vehicles, 2 there were >28.5 million natural gas vehicles (NGVs) and >33 000 natural gas fueling stations worldwide at the end of 2019. The NOx emissions of lean-burn (air/fuel equivalence ratio λ > 1) NGVs are equivalent to 90% of the United States Environmental Protection Agency standard, with 21% fewer GHGs than those emitted by comparable gasoline/ diesel vehicles.…”

“…CH 4 is a cleaner alternative to other fossil fuels for delivering reliable and affordable energy and decreasing the emissions of noxious and/or greenhouse gases (GHGs) into the atmosphere . According to the International Association of Natural Gas Vehicles, there were >28.5 million natural gas vehicles (NGVs) and >33 000 natural gas fueling stations worldwide at the end of 2019.…”

High catalytic efficiency of Pd nanoparticles immobilized on TiO2 nanorods‐coated ceramic membranes

“…However, direct application of Pd nanoparticles encounters a main challenge against the rapid agglomeration due to their high surface energies, which dramatically lowers their catalytic activities. A constructive approach is to immobilize them on some solid supports, such as carbon, membrane, silica, zeolites, polymers, ceramics, etc. The supports can be categorized into two groups: powders, and monolithic materials like membranes .…”