Cu and Co modified beta zeolite catalysts for the trichloroethylene oxidation

Abstract

In this work we have studied for the first time the catalytic activity for the oxidation of trichloroethylene (TCE) of Cu and Co beta zeolites. The results show that they are active and selective towards CO 2, obtaining a better selectivity than that reached with conventional H-zeolites. The copper and cobalt zeolites have been prepared by different methods. It was found that their activity depend on the metal and on the preparation procedure. The most active catalyst was the Cu-BEA prepared by ion exchange (T 50% = 310°C and T 90% = 360°C). This catalyst has the highest ammonia adsorption capacity (as a measurement of the acidity) and it was the only tested material in which the Me 2+ was completely reduced in a standard H 2-TPR experiment (indicative of its important redox properties). Thus, the enhanced activity of the Cu-exchanged zeolite was associated to the presence of strong acid sites in the zeolite and to the redox properties of the copper ion exchanged. The catalyst was stable at 300°C for almost 70 hours without any important deactivation. This was related to the oxidative properties of the copper that avoid the formation of coke on the strong acid sites of the zeolite. On the other hand, zeolites with the transition metal incorporated into the zeolite framework by hydrothermal synthesis showed lower catalytic activity, probably because the formation of small oxide particles with much less interaction with the silicate framework, that results in a lower redox activity of the transition metals. It has been shown that a proper combination of acidity, redox properties and metal-zeolite interaction is necessary in order to prepare an active and selective zeolite catalyst for the TCE oxidation.

Bifunctional Mg−Cu‐Loaded β‐Zeolite: High Selectivity for the Conversion of Furfural into Monoaromatic Compounds

“…Thusly, it can be considered that the formation of extra porous structure on the zeolite framework from the loading of metal species should be the main reason for increasing catalyst surface area. [28] Figures S3 and S4 show the SEM-EDX mapping images of Cu and Mg loaded b-zeolite after calcination in air. However, it should be noted that the surface area was decreased to some extent in the case of overloading of metal species amount, such as 10wt%Cu and 3 wt%Mg loadings, which should be resulted from the covering by excessive metal species or from the sintering of metal particles on the surface of b-zeolite.…”

Fabrication of mesoporous Co3O4 oxides by acid treatment and their catalytic performances for toluene oxidation

“…However, the disadvantages of these catalysts, such as high cost, easypoisoning tendency and limited resources, hinder their wide industrial application. Alternatively, various transition metal oxides have been extensively studied over the past several years as oxidation catalysts because of their advantages including a lower price and adequate catalytic activities at relatively low temperature [3][4][5][6][7][8][9][10]. Among these metal oxides, Co 3 O 4 has attracted much attention due to its excellent catalytic performance in numerous reactions, e.g., the catalytic oxidation of CO, NO or VOCs as well as soot combustion [11][12][13][14][15][16][17][18].…”

“…Li and his coworkers introduced this technique for the treatment of three-dimensionally ordered macroporous LaMnO 3 perovskite with dilute HNO 3 , acquiring a novel γ-MnO 2 -like material after the selective removal of La cations [34]. This novel sample showed a significantly higher catalytic activity for CO oxidation than the initial precursor LaMnO 3 and ordinary γ-MnO 2 oxide, which was predominantly attributed to its large specific surface area and high degree of mesoporosity.…”

A high-performance CeO2 @Pt-Beta yolk-shell catalyst used in low-temperature ethanol steam reforming for high-purity hydrogen production

“…For CeO 2 @Pt‐Beta, the peaks located at 2 θ = 28.8°, 33.3°, 47.6°, and 56.4° correspond to the planes (111), (200), (220), and (311) of the cubic fluorite structured CeO 2 (JCPDS 34–0394), respectively . On the other hand, two diffraction peaks at 2 θ = 7.9° and 22.6° found in this sample correspond to the planes (101) and (302) of the zeolite Beta, which showed lower intensity compared with Pt‐Beta . This kind of phenomenon suggests that the zeolitic phase should exist as small crystallites in the CeO 2 @Pt‐Beta.…”