High-yield synthesis of Ce modified Fe–Mn composite oxides benefitting from catalytic destruction of chlorobenzene

Abstract

Ce–Fe–Mn catalysts were prepared by an oxalic acid assisted co-precipitation method.

Research advances in chlorinated benzene-containing compound oxidation catalyzed by metal oxides: activity-enhanced strategies and reaction-facilitated mechanisms

“…Once again, the calcination temperature was confirmed to have a great influence on the CB activity of the Ce–Fe–Mn catalyst. 107 Ce–Fe–Mn calcined at 400 °C is about 99% at 250 °C, while the activity decreased with the increase in the calcination temperature, which may be related to the formation of the Mn 2 O 3 phase in 500 °C, leading to a decrease in the SSA and active oxygen.…”

“…36 As the temperature increases, the bond-breaking rate is higher than the adsorption rate; since the C-Cl bond has lower energy than C-H bond, it is more susceptible to nucleophile attack and breaking. 37,38 With the cleavage of C-Cl, phenolic esters are formed on the surface of the catalyst, which is further oxidized to quinones. CB can also be adsorbed on the surface of the catalyst first and then gradually break the C-Cl and C-H bonds under the action of reactive oxygen species.…”

“…Studies found that increasing the temperature can extrude Cl atoms from the oxygen vacancies to some extent (Ce-Fe-Mn, 250 °C), and it inferred that the removal of chloride ions is a slow step, which determines the rate of catalytic oxidation. 38 On the other hand, reactive oxygen species could promote the removal of Cl and desorb the Cl from the catalyst surface to form Cl 2 ; the higher the surface chemical oxygen uptake, the easier the removal of Cl on the catalyst surface. 93 For example, the smaller particle size of cerite Mn 8 Ce 2 /Al 2 O 3 can be dechlorinated at a lower temperature, while the CeO 2 /Al 2 O 3 is only above 500 °C.…”

“…The subsequently dissociating phenyl may react with hydroxyl radicals to form phenoxy groups or be directly oxidized to open the ring to form intermediate maleate or acetate, unsaturated hydrocarbons, or aldehydes, which are eventually oxidized by surface-reactive oxygen species. 38,44–49 The catalytic oxidation process can be concluded in Fig. 5, and the distinguished steps can be described by the following equations.CB → CB ad CB ad + [O] → C 6 H 5 * + MnCl y (MnO x Cl y )C 6 H 5 * + OH* → C 6 H 5 O* + H + C 6 H 5 O*/C 6 H 5 * + [O] → C x H y O z + O vac C x H y O z + [O] → CO 2 + H 2 O…”

Synthesis of Inexpensive Ternary Metal Oxides by a Co‐Precipitation Method for Catalytic Oxidation of Carbon Monoxide

“…[2] In recent years, iron(III) oxide (Fe 2 O 3 ) has attracted much attention from researchers due to its high activity as a substrate for redox catalytic materials. [6][7][8][9] In nature, iron oxide exists in both Fe 2 + and Fe 3 + oxidation states. The conversion ability between states of Fe 2 + and Fe 3 + becomes more flexible when they are in contact with the different chemical natures of other transition metal oxides, causing more oxygen vacancy formation and thus facilitating redox catalysis.…”