A comparative study of manganese–cerium doped metal–organic frameworks prepared via impregnation and in situ methods in the selective catalytic reduction of NO

Abstract

aMn and Ce were loaded on metal-organic frameworks (MOFs) via impregnation and in situ doping methods. The catalytic capacities of the obtained composite materials were evaluated in the selective catalytic reduction (SCR) of NO. The existing form of Mn-Ce in the MOF originates from different doping methods and its effect on the catalytic performance was investigated. Mn-Ce introduced by impregnation was deposited on the surface of the MOF and exhibited high catalytic efficiency of more than 98% from 200 C to 300 C. According to the results of BET, XRD, XPS, and ICP analyses, it was concluded that Mn-Ce introduced via the in situ doping method was inserted in the crystal lattice structure of the MOF, which resulted in an enlarged surface area, low Mn concentration, and poor redox property as compared to that introduced via the impregnated method. By exploring these factors, it was proven that the limited redox ability was the direct reason that resulted in the low activity of the MnCeMOF. Using thermal decomposition, the in situ doped Mn-Ce was liberated from the MnCeMOF crystal lattice and subsequently, exhibited recovered redox properties and catalytic activity. In this study, we proved that different doping methods lead to different forms of Mn-Ce in the MOF, which exhibit different redox properties and thus directly lead to different catalytic performance.

Spatially Nanoconfined Architectures: A Promising Design for Selective Catalytic Reduction of NOx

“…The introduction of Mn and Ce to UiO-67 by impregnation method enabled the great redox property of MnCe@MOF catalyst, which exhibited better NH 3 À SCR activity than MnCe-MOF catalyst prepared by in-situ doping method. [106] Shi et al reported that the introduction of Cu + species into the framework of MIL-100(Fe) via a hydrothermal method. could further boost the NH 3 À SCR activity of MIL-100(Fe).The newly formed activity sites and the interaction between Cu + species and Fe sites were the main reasons for the improved activity.…”

“…The loading method also has a significant effect on the MOFs supported catalyst for NH 3 −SCR. The introduction of Mn and Ce to UiO‐67 by impregnation method enabled the great redox property of MnCe@MOF catalyst, which exhibited better NH 3 −SCR activity than MnCeMOF catalyst prepared by in‐situ doping method [106] . Shi et al.…”

Improving the photocatalytic hydrogen evolution of UiO-67 by incorporating Ce4+-coordinated bipyridinedicarboxylate ligands

“…So far as we know, only a few studies have examined the interaction between different linkers in MOFs and energy transfer between them leading to photocatalytic activities [25,32,[34][35][36]. It is known that Ce can promote energy transfer due to its low-lying empty 4f orbitals and act as active sites for H 2 evolution [37][38][39][40][41][42]. In this work, we introduced Ce 4+ into UiO-67 to form UiO-67-Ce by replacing some bpdc of UiO-67 with bpydc-Ce (namely, a complex formed by bpydc coordinated with Ce 4+ ) and demonstrated that the photocatalytic H 2 evolution rate is greatly enhanced over UiO-67-Ce than UiO-67.…”

Catalytic oxidation of NO over MnOx–CoOx/TiO2 in the presence of a low ratio of O3/NO: activity and mechanism

“…High specic surface area is helpful for the adsorption performance of the catalyst. 22,35 However, as shown in Fig. 8(a) and (c), NO oxidation efficiencies increased with the total loading from 7% to 15%, which demonstrated that the loading amount or the content of active component was the main factor inuencing the catalytic activity when compared to the specic surface area.…”