Characterization of a Novel Laminar-Flow Oxidation Reactor for Simulating Atmospheric Multiple-Day Oxidation
TOBIAS REINECKE, Markus Leiminger, Andreas Klinger, Todd Rogers, Martin Graus, Markus Mueller, IONICON Analytik GmbH., Innsbruck, Austria
Abstract Number: 160
Working Group: Instrumentation and Methods
Abstract
Rapid photochemical oxidation in small volume reactors is a useful tool to mimic atmospheric processes of days within minutes. The new automatable Laminar-flow Oxidation Reactor (ILOx) consists of a 110 cm long Quartz glass tube with a total internal volume of 8 l that is irradiated by 480 W UVA LEDs. Based on the total reactor flow, typical residence times range from 2 to 16 min. Oxidants can be introduced through multiple customizable inlet ports. To achieve laminar flow conditions, sample injection is CFD optimized to suppress any formation of injection jets. The outlet of the ILOx Reactor allows for sampling both particles and VOCs simultaneously, with VOC core-sampling to reduce wall interactions and potential formation of artifacts. All wetted materials are optimized for purest experiments.
To experimentally confirm the oxidation potential of the reactor, air containing ~2 ppbV of toluene is sampled through ILOx and VOCs were monitored by FUSION PTR-TOF. Just 2 minutes after starting the UVA irradiation, 50% of toluene is oxidized, while atmospheric lifetimes are in the range of 2 days. In addition known toluene oxidation products like methyl glyoxal, cresols or dihydroxymethyl benzene are increasing. MCM 3.3.1 simulations of this experiment result in average OH concentrations of 3x108 cm-3, which equals to an OH exposure OHexp of 1011 cm-3s.
To characterize particle transmission, polydisperse ammonium sulfate particles were injected into the ILOx. The particle distribution at the inlet and outlet of the ILOx was measured by an SMPS system (SMPS+C, Grimm Aerosol Technik, Germany) to assess potential particle losses. Even with maximum UVA irradiation, no significant change in the particle distribution and intensity of ammonium sulfate aerosol is measurable, proving highly efficient particle transmission of the system.
We will present a comprehensive characterization of the ILOx reactor, highlighting benefits and limitations.