Research Of The MEMS Methane Catalytic Combustion Micro-sensor Based On Nano-catalyst

Nowadays, the gas sensor moves forward around low power consumption, micromation and intelligence. With the development of the micro-electro-mechanical system (MEMS), the methane catalytic combustion sensor based on MEMS technology has become an important research area. In this thesis methane catalytic combustion MEMS sensor based on rhodium oxide and ruthenium oxide catalyst were fabricated. Their sensing performances were also researched herein.1) Different mole ratio rhodium oxide/alumina hybrid (the mole ratio of Rh/Al=1:1,2:1,4:1, 8:1) have been prepared following a facile one-pot self-assembly approach using P123 as template. The materials have been characterized with TEM, XRD, EDS, XPS, BET analysis, which found that the materials all owned uniform mesoporous structure and displayed high dispersions of both the noble metal oxide and alumina. During the catalytic activity and stability tests, the 4:1 Rh2O3/γ-Al2O3 (Rh:Al=4:1) materal showed the highest catalytic activity and stability. The MEMS sensor made from it showed short response time, high sensitivity and good resistance to H2S.2) Ruthenium oxide/alumina and ruthenium oxide/cerium oxide hybrid have been fabricated by immersion method. From the TEM, XRD, EDS, XPS, BET analysis, it was found that ruthenium oxide evenly dispersed on cerium oxide and showed better catalytic performance than that of ruthenium oxide/ alumina hybrid. Using cerium oxide as supporter and ruthenium oxide as catalyst, MEMS gas sensor was fabricated by Spin-Coating method. The sensor performance tests showed good linear relation between output signal and concentration of lean methane. Long time test showed that this sensor has lower power consumption, short response time and good stability.3) For ruthenium oxide catalytic system, zinc aluminate supporter was also used in our MEMS sensor. Two methods (sol-gel method and micro-emulsion method) were used to synthesize zinc aluminate supporter in the thesis. After loaded with ruthenium oxide, the catalytic properties of materials were tested through fix-bed catalysis instrument. The ruthenium oxide/zinc aluminate hybrid synthesized by micro-emulsion method showed lower firing point than that from sol-gel method. MEMS sensor based on micro-emulsion method showed good stability and short response time. But the output signal was slightly lower compared with other supporter.