Hierarchical MnO_x/Co₃O₄ Nanoarrays on Ni Foam for Catalytic Oxidation of Volatile Organic Compounds

Abstract

Hierarchical Co 3 O 4 /MnO x and MnO x /Co 3 O 4 nanoarrays were successfully prepared by primary and secondary hydrothermal process on the Ni foam (NF), and the synthesized monolithic catalyst was used for catalytic combustion of toluene. Similarly, the monolithic Co 3 O 4 /NF, and MnO x /NF nanoarray catalysts were also prepared with the same method. Notably, toluene catalytic oxidation test proved that the catalytic performance of these monolithic catalysts followed this order: MnO x / Co 3 O 4 /NF > Co 3 O 4 /MnO x /NF > Co 3 O 4 /NF > MnO x /NF and the monolithic MnO x /Co 3 O 4 /NF catalyst showed the excellent toluene oxidation performance (T 90 = 238 °C). Interestingly, the monolithic MnO x /Co 3 O 4 /NF catalyst also showed good stability for the toluene oxidation, which makes it a possible candidate to replace noble-metal catalysts. Through XPS and H 2 -TPR analysis, we are proved that the monolithic MnO x /Co 3 O 4 /NF catalyst has more active species (Co 3+ , Mn 3+ and Mn 4+ ), rich lattice oxygen, better interaction between Cobalt and Manganese, and excellent reducibility, which jointly promoted the conversion of toluene. In situ DRIFTs result over the monolithic MnO x /Co 3 O 4 /NF catalyst verified that the benzoate and anhydride species were the key intermediates of toluene catalytic combustion and the possible reaction path was likely as followed: toluene → benzoate → benzoquinone → maleate or maleic anhydride → formaldehyde or acrolein →••• → CO 2 and H 2 O.

Spatially Separated Redox Cocatalysts on Ferroelectric Nanoplates for Improved Piezophotocatalytic CO2 Reduction and H2O Oxidation

“…The high-resolution O 1s spectrum can be deconvoluted into three peaks corresponding to O–Ti of PbTiO 3 , O–H of adsorbed OH groups, and O–Mn of deposited MnO x (Figure d). According to the Mn 2p spectrum, Mn 4+ , Mn 3+ , and Mn 2+ chemical states are involved in MnO x , which is in accordance with a previous report (Figure e) . The binding energies of Au 4f 5/2 and Au 4f 7/2 in the Au 4f spectrum are in good agreement with zero valence Au (Figure f), while the Cu 2p spectrum in Figure g indicates the coexistence of dominant Cu(0) and a trace amount of Cu­(II), suggesting the partial oxidation of surface Cu atoms in the loaded AuCu.…”

Metal–Organic Framework-Derived Hollow CoMn2O4 Nanocube Catalysts for Deep Toluene Oxidation

“…Introduction of Co into Mn-based catalysts can not only enhance the specific surface area but also regulate the lattice defects and oxygen migration rate, resulting in higher catalytic activity. 7,8 Metal−organic frameworks (MOFs) have been proven to be a potential new material in catalysis by many researchers on account of the structural tunability, high porosity, and specific surface area. 9−13 An effective strategy to prepare porous hollow Mn−Co oxides via pyrolysis of MOFs has shown high catalytic efficiency for VOCs oxidation.…”

“…It has been proven that Mn–Co bimetallic oxides possess higher activity than single Co or Mn oxides during the catalytic degradation of toluene. Introduction of Co into Mn-based catalysts can not only enhance the specific surface area but also regulate the lattice defects and oxygen migration rate, resulting in higher catalytic activity. , …”

Nickel Nanoparticles for Liquid Phase Toluene Oxidation – Phenomenon, Opportunities and Challenges

“…In recent years, the catalytic applications of 3d transition metal nanoparticles, composites and foams were rapidly growing in popularity because of their advantages such as low cost, abundant accessible redox active sites and really good mass transfer ability. [1][2][3][4][5][6] These properties and their suitable catalytic activities made them viable candidates to replace the expensive platinum group metals used as conventional catalysts in many organic transformations. [7][8][9][10] Among these, supported and unsupported nickel catalysts have one of the most versatile catalytic potentials, covering not only cross-coupling reactions but also redox transformations in liquid or gas phase.…”

“…In recent years, the catalytic applications of 3d transition metal nanoparticles, composites and foams were rapidly growing in popularity because of their advantages such as low cost, abundant accessible redox active sites and really good mass transfer ability [1–6] . These properties and their suitable catalytic activities made them viable candidates to replace the expensive platinum group metals used as conventional catalysts in many organic transformations [7–10] .…”