Abstract
Mesoporous CeO2:Mn3O4 materials (3:7 and 7:3 molar ratio) were prepared by co-precipitation and deposited as porous thick films over alumina (Al2O3) planar substrate provided with Pt meander. The aim was oriented towards detecting low levels methane (CH4) at moderate operating temperatures. Herein we demonstrated that the sensitivity of catalytic micro-converters (CMCs) towards a given peak of CH4 concentration corresponds to specific gas-surface interaction phenomena. More precisely, a transition from thermal conductivity to combustion rate is likely to occur when CMCs are operated under real atmospheric conditions (normal pressure, presence of relative humidity, and constant operating temperature). The response to CH4 was analyzed over different gas flows and different gas concentrations under the same operating regime. The materials were fully characterized by adsorption-desorption isotherms, H2-Temperature Programmed Reduction (H2-TPR), X-ray Diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Scanning Electron Microscopy (SEM), and Raman spectroscopies. Thus, the applicative aspect of using CeO2:Mn3O4 as moderate temperature CMC for CH4 detection is brought to the fore.
Highlights
The working principle of a pellistor gas sensor is based on “burning” phenomena
Continuing in this research line, we developed a novel interpretation of the gas sensing effects based on the CeO2 :Mn3 O4 catalytic micro-convertors envisaging the CH4 detection
We can depending on the molar ratio used in the synthesis, the CeO2 :Mn3 O4 materials to possess different expect that, depending on the molar ratio used in the synthesis, the CeO2:Mn3O4 materials to possess active sites that influence the overall catalytic activity
Summary
The working principle of a pellistor gas sensor is based on “burning” phenomena. Another issue encountered with classical pellistor sensors was related to the sensitive element poisoning, which shortens the sensors’ life [1]. P. Krebs et al reports pellistor manufacturing onto silicon involving thin film deposition and micromachining techniques [2] which achieve a sensitivity to methane in air of about 13 mV/% CH4 when operated at 400 ◦ C. Aigner et al proposed to operate the pellistor under pulsed temperature modulation (PTM) mode as an alternative to the classic approach [3]. Li et al presented a pellistor system with low energy consumption of up to 30% and a sensitivity of 2.4 mV/% CH4
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