Catalytic Combustion of Lean Methane Assisted by an Electric Field over Mn_xCo_y Catalysts at Low Temperature

Abstract

An electric field was introduced into the catalytic oxidation of lean methane at low temperature over Mn x Co y catalysts. Mn1Co5 exhibited the best catalytic performance with the light off temperature (T 50) as low as 271 °C in the electric field, nearly 60 °C lower than that in a conventional reaction system. The electric field promoted the formation of octahedrally coordinated Mn3+ with active oxygen species released from the reduction of octahedrally coordinated Co3+ in Co3O4 spinel. Also, octahedrally coordinated Mn3+ sites were proven to be the main active sites for methane catalytic oxidation. With an in situ FTIR technique, it was found that the oxygen species from the catalyst bulk instead of gaseous oxygen will adsorb on the octahedrally coordinated Mn3+ sites in the electric field, promoting the activation of CH4 at low temperature. The dehydroxylation process will be accelerated through the formation of CoO­(OH) species that will quickly convert due to the enhanced reducibility of Co3+ in the electric field, weakening the inhibition of produced hydroxyl species on active sites. Based on the experimental results, the mechanism of catalytic oxidation of CH4 over Mn x Co y catalysts in an electric field was proposed.

Sr-Doped Cubic In2O3/Rhombohedral In2O3 Homojunction Nanowires for Highly Sensitive and Selective Breath Ethanol Sensing: Experiment and DFT Simulation Studies

“…It should be further noticed that the gas sensing performance of 8 wt % Sr-doped In 2 O 3 outperforms the 10 wt % one, inferring the effective homojunction between c-In 2 O 3 and rh-In 2 O 3 . The optical band gap of c-In 2 O 3 was reported to be 3.7 eV, higher than that of rh-In 2 O 3 (3.0 eV), and there would be Fermi level difference of ∼0.1 eV, leading to the formation of electron depletion and building-in voltage as shown in Figure S8. ,, The potential would further activate the chemisorbed oxygen, enhancing the surface reaction of eq , which is similar to the recently published enhanced catalyst reaction by electric field . Therefore, all the enhanced ethanol adsorption, rh-phase stabilization, rh(104) facet exposure, and enhanced surface reaction by Sr doping contribute to the high ethanol sensing performance of the homojunction c-In 2 O 3 /rh-In 2 O 3 NWs.…”

Low-Temperature Methane Oxidation Triggered by Peroxide Radicals over Noble-Metal-Free MgO Catalyst

“…The bands at 2342 and 2359 cm –1 are attributable to the carbon dioxide (CO 2 ) gas phase , and the ones at 2175 and 2025 cm –1 to gaseous carbon monoxide (CO) adsorbed on the terrace of MgO, , and the linearly bonded CO gas phase, , respectively. Herein, the bands at 1435, 1508, and 1520 cm –1 can be attributed to carbonate signals while the ones at 1610 and 1340 cm –1 to formate intermediates according to the reported studies. , …”

“…Herein, the bands at 1435, 1508, and 1520 cm −1 can be attributed to carbonate signals 61 while the ones at 1610 and 1340 cm −1 to formate intermediates according to the reported studies. 61,62 Figure 6 also indicates that the signals arising from the formate weaken in terms of intensity under air atmosphere, due to the further transfer reaction from formate to carbon oxides with an increase in the evaluated temperature. 12 Therefore, it can be inferred that methane can be partially oxidized to formate or carbon oxides over the M3 sample at low temperature, even in the absence of air.…”

A prototype for catalytic removal of formaldehyde and CO in a compact air cleaner powered by portable electricity

“…S3), which is in agreement with the reported findings that the activated energies of lean methane oxidation were lowered by assisting electric field. 15,16 In comparison with the works employing carbon materials as supports, [7][8][9] the electric current passed through the catalyst itself and the actions of the electricity on the reactions were beyond the Joule heating from the support in this work. Therefore, the prototype of the air cleaner powered by portable electricity can exhibit higher performance for the removals of the pollutants than the traditional thermal heating way.…”