European Network on New Sensing Technologies for Air Pollution Control and Environmental Sustainability - EuNetAir COST Action TD1105 Microwave synthesis of nanooxides and their applications in microwave gas sensing J Rossignol, B. De Fonseca , Pr D. Stuerga , Pr P Pribetich COST is supported by the EU Framework Programme ESF provides the COST Office through a European Commission contract Overview Synthesis of nanopowders Microwave gas sensing 2 Bourgogne 3 GERM Modeling Design of microwave reactors Microwave transduction Microwave field distribution Microwave synthesis Liquid and gas sensing SnO2, TiO2, ZrO2, Fe2O3… Microwaves? Frequency: 300MHz to 300GHz Wave length1mm and 1m (er=1) Our Microwave synthesis The RAMO System Resonant cavity Core heating Circulator Pressure control Milliwattmeter In situ measurements Temperature control Atmosphere control RATES : temperature 5 to 15°C.s-1 pressure 1.2 MPa.min-1 2 kW Generator Waveguide Synthesis of nanopowders The RAMO System Resonant cavity Oxide precursor, hydrochloric acid Circulator Milliwattmeter Initial power 1 kW Microwave heating duration ≤60 s Reaction TiO2 SnO2 µm nm Size BET confirmed by DRX 2 kW Generator SnO2 Tin oxide (IV) by microwave thermohydrolysis (RAMO) : SnCl4 (Aldrich, 99,995%) + HCl (Prolabo, RP NormapurTM) DRX  Cassiterit (Fiche JCPDS 41-1445) Microsonde XDE  Any trace of Cl SnH O   4 2 6  4Cl  One Step  SnO2  4 H 3O   4Cl  TEM SEM 1 μm HRTEM 10 nm 5 nm WIPO: WO/2009/050344, Method for preparing nanoparticles of complex metal oxide), with exclusive exploited licence to the society Naxagoras Technology. TiO2 Rutile Anatase TiH 2O6 4   4Cl  One Step  TiO2  4 H 3O  4Cl  Difference of surface acidity Effect of adsorption Microwave gas sensing Pollutant gas Incident wave Reflected wave Reflected wave Γ 𝑓 = Incident wave Γ 𝑓 = Re + j Im 1 frequency 1600 frequencies 2 informations a Signature SnO2 , pollutant NH3 Re () 10-4 Variation de la partie imaginaire x 10000 𝝴  25 Im () 10-4 TiO2, pollutant NH3 𝝴  85 2,5 2 300 ppm Variation de la partie imaginaire x 10000 Im () 1,5 1,0 10-4 500 ppm 200 ppm 400 ppm 100 ppm 0,5 -0 0 ppm -0,5 -1,0 -1,5 -3 -2 -1 0 1 2 Re ()Variation de la partie réelle x 10000 -4 10 3 4 5 6 Conclusions and challenges An innovative approach to gas sensing:  Microwave synthesis of nano metal oxide  Microwave gas sensing Future investigation:  Impact of the size, the porosity and the specific surface area of the metal oxide on the reflected coefficient   Effect of the temperature and humidity on the sensor’s response  Knowledge of the interaction phenomena and modeling of the sensor ‘s response.