Thermal Stabilities of MCM-41-Modified Pd/Al₂O₃ for Ethanol Adsorption and Oxidation

Abstract

The thermal stabilities of palladium (Pd) catalysts supported on MCM-41-modified Pd/Al2O3 calcination at 1000 °C were investigated for the adsorption and catalytic combustion of ethanol. MCM-41 (0, 30, 50, 70, and 100 wt %)-modified Al2O3 materials were prepared by the in situ coprecipitation method. The catalysts were characterized by N2 adsorption–desorption, X-ray diffraction, and scanning electron microscopy–energy dispersive spectrometry. It was found that MCM-41 less than 50 wt % was conductive to the increase in specific surface area and pore volume of the catalysts even after 1000 °C calcination which had a positive relationship with the adsorption performance of ethanol. Pd/Al2O3, prepared in this study, presented a sheet-like morphology which could attach on the surface of MCM-41. Meanwhile, the introduction of MCM-41 into Al2O3 could hinder the phase transition of γ-Al2O3 to δ-Al2O3 and prevent the collapse of the pore structure in MCM-41, thus avoiding the aggregation of Pd particles effectively at 1000 °C. Cat-50% (50 wt % MCM-41 into Pd/Al2O3) showed the best ethanol adsorption performance with the longest breakthrough time and highest adsorption capacity at 40, 60, and 80 °C because of its good textual properties, while Cat-70% presented the highest activity with higher CO2 yield at 200 °C, reaching 90% ethanol conversion at 220 °C, owing to its good dispersion of Pd particles. In addition, the introduction of MCM-41 could inhibit the production of acetaldehyde to some extent. The long-term stability test demonstrated that MCM-41-modified Pd/Al2O3 had good stability for catalytic oxidation of ethanol for the stable conversion for 500 h at 300 °C and gas hourly space velocity of 10,000 h–1.

Sorption and Reaction of Biomass Derived HC Blends and Their Constituents on a Commercial Pt–Pd/Al2O3 Oxidation Catalyst

“…10). In the literature, LO-temperatures of 423-523 K for the conversion of ethanol have been observed for Pd/Al 2 O 3 catalysts by Liu et al [41]. The decrease in ethanol conversion is already apparent at 383 K. The analysis of blend 1 shows that the conversion of ethanol to acetaldehyde and acetic acid is significantly lower (average conversion of 45%) than the measurement with pure ethanol (average conversion of 64%).…”

“…On the left side the HC is shown in the composition of blend 1 and on the right side of blend 2, filtered by a Savitzky-Golay-Function of 3rd polynomial order and a window size of 90, T = 383 K and GHSV = 60,000 h −1 , gas composition: 8% H 2 O, 8% O 2 , 0% CO 2 , HC: see legend, balance: N 2 also lead to the formation of acetaldehyde and acetic acid [38][39][40]. It is known that Al 2 O 3 has a poor adsorption behavior for ethanol because of its low specific surface area [41]. It is therefore assumed that the storage assigned to ethanol is mainly caused by adsorbed reaction products.…”

Pd/SiO2 Catalysts Prepared via a Dielectric Barrier Discharge Hydrogen Plasma with Improved Performance for Low-Temperature Catalytic Combustion of Toluene

“…The 0.5% Pd/SiO 2 catalyst without H 2 reduction exhibited a characteristic peak (2 theta = 33.4°) associated with PdO. 49,50 After the H 2 -reduction process at 300 °C, the 0.5% Pd/SiO 2 -R catalyst exhibited a characteristic peak (2 theta = 39.8°) with Pd instead of PdO. 20 Notably, the characteristic peak of Pd vanished on the 0.5% Pd/SiO 2 -P catalyst from the result of XRD pattern.…”

Optimization of Mn‐Mg‐Al Mixed Oxides Composition on their Activity towards the Total Oxidation of Aromatic and Oxygenated VOCs

“…[5] Noble metals are widely used for VOC oxidation due to their catalytic performance despite their high cost and low resistance to sintering and poisoning. They are generally used as active phases supported on porous materials (silica-based, [6][7][8] aluminabased, [9][10][11] zeolite-based, [12,13] etc.) ensuring their dispersion on the surface and inside the pores.…”