A spectroscopic study on the detection of carbon monoxide for solar fuel production

Abstract

The synthesis of value-added hydrocarbons from CO2 shows great potential for storing energy from intermittent renewable energy sources, while also being CO2 neutral. The process limiting step is the conversion of CO2 to CO. Non-equilibrium plasma discharges like the TALIF or microwave discharges have been proposed to achieve efficient dissociation, while keeping investment costs low. To measure conversion efficiency, a detection method is required for CO, which can be achieved using TALIF. In contrast to absorption spectroscopy methods, TALIF can yield spatially and temporally resolved CO measurements. A setup has been realized to excite ground-state CO to the electronically excited state. This is done using a frequency tripled Nd:YAG laser (355 nm) to pump a tunable dye laser containing a Coumarin 460 solution with subsequent frequency doubling to generate 230 nm. A gated ICCD camera is used to detect emission (450 nm-750 nm) in the Ångström band ( ). Measurements in a reference cell filled with pure CO show an optimal excitation wavelength of 230.015 nm, while good signal-to-noise ratio spectra can be obtained at pressures between 10 mbar and 1000 mbar. Quenching effects however influence fluorescence yields significantly, especially at pressures above 250 mbar. Measurements in the exhaust of a DBD performed at different pressures show similar CO production trends found by absorption spectroscopy at 200 mbar. At higher pressures the trends start to deviate from absorption measurements as a result of an increase in quenching rates due to high CO self-quenching.

Date of Award	30 Nov 2015
Original language	English
Supervisor	Richard A.H. Engeln (Supervisor 1) & P.D. Machura (Coach)