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

• Published in: Industrial & engineering chemistry research Vol. 59; no. 13; pp. 5474 - 5481
• Main Authors: Liu, Jianying, Li, Junjie, Hou, Xiaoxiao, Xu, Chenghua, Zhang, Xueqiao, Luo, Lanni
• Format: Journal Article
• Language: English
• Published: American Chemical Society 01.04.2020
• ISSN: 0888-5885; 1520-5045
• DOI: 10.1021/acs.iecr.9b06258

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.