Metal-Loaded Mesoporous MCM-41 for the Catalytic Wet Peroxide Oxidation (CWPO) of Acetaminophen

Abstract

MCM-41 based catalysts (molar ratio Si/Al = 40) were prepared by a hydrothermal route, modified by ionic exchange with different metals (Cu, Cr, Fe and Zn) and finally calcined at 550 °C. The catalysts were fully characterized by different techniques that confirmed the formation of oxides of the different metals on the surfaces of all materials. Low-angle X-ray diffraction (XRD) analyses showed that calcination resulted in the incorporation of metallic Zn, Fe and Cr in the framework of MCM-41, while in the case of Cu, thin layers of CuO were formed on the surface of MCM-41. The solids obtained were tested in the catalytic wet peroxide oxidation (CWPO) of acetaminophen at different temperatures (25–55 °C). The activity followed the order: Cr/MCM-41 ≥ Fe/MCM-41 > Cu/MCM-41 > Zn/MCM-41. The increase of the reaction temperature improved the performance and activity of Cr/MCM-41 and Fe/MCM-41 catalysts, which achieved complete conversion of acetaminophen in short reaction times (15 min in the case of Cr/MCM-41). Fe/MCM-41 and Cr/MCM-41 were submitted to long-term experiments, being the Fe/MCM-41 catalyst the most stable with a very low metal leaching. The leaching results were better than those previously reported in the literature, confirming the high stability of Fe/MCM-41 catalysts synthesized in this study.

Tuning the basicity of the Ni@MCM-41 catalyst via alkaline earth metal oxide promoters for CO2 reforming of CH4

“…41 In addition, the enhancement of the pore diameter of promoted and unpromoted samples compared to that of the parent material was a result of the integration of the nanoparticles into the support structure throughout the heat treatment. 42 It should be noted that among all the samples, the pore volume of Ba(5%)/Ni(15%)@MCM-41 was the smallest (0.31 cm 3 g −1 ), which indicated that a significantly larger amount of metal atoms were anchored in the hexagonal mesopores of MCM-41. 39 The surface properties and morphology of the prepared samples were explored via SEM analysis (Fig.…”

Reactivity of Group 5 and 6 Single-Site Photocatalysts for Partial Oxidation of Methane: Comparison of Chromium, Niobium, and Tungsten-Doped Mesoporous Amorphous Silica

“…Adsorption rate constants were determined using collision theory as k normala = 1000 A N normalA 4 [ g a s ] ( 8 R T π M ) 1 / 2 where R is the gas constant, T is the temperature, M is the molar mass, A is the area of the active site (1.27 × 10 –18 m 2 ), and [gas] is the concentration of the adsorbing methane or methanol molecules. The rate of photoactive MO x species activation is calculated by k normala normalc normalt = normalΦ w I 2 h c ( λ f 2 − λ i 2 ) ( w t % ) where Φ is the quantum yield, I is the photon intensity, w is the weighting factor for the percentage of the incident photons irradiating the photocatalyst that are in a specific wavelength range, h is Planck’s constant, c is the speed of light, (λ f 2 – λ i 2 ) gives the range of photon wavelengths that will activate the photocatalyst, and the wt % factor is the experimental weight percent of metal loading for each of the transition metals doped into the MCM-41 amorphous SiO 2 (1.91% for Cr, 3.5% for Nb, 20.0% for W). ,, The Cr, Nb, and W MO 4 /MCM-41 materials activate under UV light giving w = 0.05 to account for the 5% of total solar irradiation in the UV range λ f = 400 nm and λ i = 100 nm. I is measured as 1370 W m –2 for solar irradiance, , while Φ is set as a stochastic array of activation percentages to observe the changes to the POM mechanism on the MO 4 /MCM-41 materials during the MKM simulations.…”

“…In this article, we elucidate the photoexcitation manifolds and properties along with the POM mechanisms of single-site photocatalysts based on CrO 4 , NbO 4 , and WO 4 embedded on the surface of MCM-41 amorphous SiO 2 micropores. − These three metals were chosen because they are close to vanadium to allow a comparison in the properties, have been synthesized previously, are in groups 5 and 6 where a number of oxidation states are possible, and cover the first three periods of the transition metal series. We first describe the computational methodology used in this study.…”

A review on the degradation of acetaminophen by advanced oxidation process: pathway, by-products, biotoxicity, and density functional theory calculation

“…In addition, oxalic acid, formic acid, and acetic acid were the main transformation products when metal-loaded mesoporous for the catalytic wet peroxide oxidation of ACT. 35 Fenton oxidation applied by De Luna et al 75 to degrade ACT. The by-products were hydroquinone, benzoic acid, benzaldehydes and some non-aromatic products like carboxylic acid, alcohols, ketones, and aldehydes.…”