Research

Desigining a novel microreactor cell to allow in-situ IR spectroscopy under microwave heated reaction conditions Slide 1
Structure of talk *Background *Cell design *Testing (Heating of CO) * Reaction results (Platinum catalysed CO oxidation) *Other work Slide 2
Background *Microwaves are elctromagnetic waves * *Wavelength 1cm to 1m *Frequency 30Ghz to 300MHz *Used for communication. RADAR, heating Slide 3
*Microwave heating can cause large rate enhancement *Well understood for liquid samples *Not for solids Slide 4
Microwave heating can cause *Unconventional temperature profiles *Thermal runaway *Electrical discharge *possible microwave effect Slide 5
Aim to develop a system that allows interrogation of catalyst samples by infrared spectroscopy under reaction conditions when heated by microwave radiation Slide 6
Design uses parallel plate applicator Slide 7
Applying oscillating voltage of correct frequency between plates creates a microwave field Slide 8
Use brass plates 30 by 50 mm and 13mm diameter pressed disk sample Slide 9
Use creamic sample holder with gas connections outside field Slide 10
Picture of ceramic sample holder Slide 11
Seal with high purity kalrez o rings Slide 12
Place calcium fluoride windows in the applicator plates Slide 13
Cover windows with fine Ni gauze Slide 14
View of applicator plate showing calcium fluoride windows covered with gauze Slide 15
View of assembled microwave reaction cell Slide 16
Carbon dioxide spectrum shows P and R baranches according to the rotational energy distribution Slide 17
Simulated spectra show change in population of rotational energy levels upon heating Slide 18
Small change in rotational energy levels not immediately clear Slide 19
Use one spectrum as background for another Slide 20
Using similar background accentuates spectral differences Slide 21
Similar peak broadening effects are seen under microwave and conventional heating due to population of higher rotational energy levels Slide 22
Time resolved spectra obtained under oscillating microwave power to gain possible kinetic information and eliminate microwave switching problems Slide 23
Time resolved infrared spectra showing thermal peak broadening and demonstrating rapid heating and cooling of carbon monoxide under microwave heating regime Slide 24
Time resolved IR and MS showing the carbon monoxide oxidation reaction oscillating under microwave heating Slide 25
Mass spectrometry showing CO oxidation occurs similarly under microwave and conventional heating Slide 26
*Cell performs as expected *Reaction can be followed by MS and IR *No microwave enhacement for CO oxidation Slide 27
View of microwave heated diffuse reflectance cell and emission IR set up Slide 28