QUAREC: description and transnational access
The Physical Chemistry Department of the University of Wuppertal has several indoor chambers of various volumes for the investigation of the photooxidation of volatile organic compounds (VOCs) at ppb and ppm concentration levels. The kinetic and product data produced by investigations in the reactors can be used to elucidate atmospheric oxidation mechanism and access the fate of chemicals in the atmosphere. QUAREC is the largest and most versatile of the reactors and is part of the Transnational Access of Euochamp-2.
2. Description of the research facility
The physical chemistry department of the Bergische University of Wuppertal was headed by Prof. K. H. Becker up to 2001 and is now under the supervision of Prof. Th. Benter. The department has over 30 years specialist experience in the investigation of atmospheric gas phase photo-oxidation processes. Recently the activities of the department have been considerably extended to include the investigation of atmospherically relevant heterogeneous reactions, aerosols, modeling and field measurements. The appointment of Prof. Benter as department head has also added specialist knowledge on atmospheric pressure mass spectrometric analysis techniques to the group. Apart from national atmospheric science projects the senior members of the department have been involved in and also co-ordinated many European framework projects on atmospheric science. The organization was heavily involved in the building of the EUPHORE photoreactor in Valencia, Spain and presently, with other chamber-owning groups, provides advice on the running of the facility. The department has co-ordinated the German tropospheric ozone research program TFS-LT3 and was instrumental in the organization of the BERLIOZ field campaign in Berlin in the summer of 1999.
2.1. Technical data
The QUAREC reactor consists of two quartz glass cylinders connected by a central enamel flange ring and silicon rubber seals and is closed at both ends by aluminum flanges. It has a total length of 6.2 m and an inner diameter of 0.47 m. A schematic representation of the reaction chamber experimental setup is shown in section 2.2 Images. The reactor can be evacuated by a turbo molecular pump (Leybold-Heraeus PT 450) backed by a Leybold D65B double stage rotary vacuum pump to a pressure of less than 10-3 mbar. To ensure homogeneous mixing of the reactants three fans with Teflon blades are mounted inside the chamber. Both end flanges contain inlet systems for reactants and bath gases and ports for mounting pressure and temperature measurement instruments. A gas flow controller can be used for the compensation of total pressure within the reactor when using analytical instrumentation that requires high volume gas samples.
The chamber is equipped with 32 super actinic fluorescent lamps (Philips TL 05/40 W: 320<λ<480 nm, λmax=360 nm) and 32 low-pressure mercury lamps (Philips TUV40W, λmax=254 nm) which are spaced evenly around the reaction vessel. The lamps are wired in parallel and can be switched individually, which allows a variation of the light intensity, and thus also the photolysis frequency/radical production rate, within the chamber. A White type multi- reflection mirror system with a base length of (5.91▒0.01) m for sensitive in situ long path absorption monitoring of both reactants and products in the IR spectral range is mounted on the flanges. The White system is operated at 82 traverses, giving a total optical path length of (484.7▒0.8) m. IR spectra are generally recorded with a spectral resolution of 1 cm-1 using a NICOLET NEXUS FTIR spectrometer equipped with a liquid nitrogen cooled (77 K) mercury-cadmium- telluride (MCT) detector.
The reactor can be temperature regulated within the range 283-313 K with a precision of ▒1 K.
Aerosol measurements can be made in the reactor using a scanning mobility particle sizer (SMPS) system. The Model 3934 SMPS system consists of an electrostatic classifier and two independent condensation particle counters (CPC) (TSI 3022 A connected to the classifier and a stand-alone TSI 3025 ultra-fine condensation particle counter UCPC).
Outlet ports are located on the end flanges to which monitoring instrumentation can be attached. An outlet port for particle sampling is located on the central flange of the reactor.
The following publications serve to demonstrate the types of investigations which can be performed in the reactor:
Temperature dependence of the gas-phase reactions of Cl atom with propene and 1-butene between 285 < T < 313 K Ceacero-Vega, B. Ballesteros, J. Albaladejo, I. Bejan, I. Barnes Chemical Physics Letters 484 (2009) 10-13.
FTIR relative kinetic study of the reactions of (CH3CH2)2S and CH3CH2SCH3 with OH radicals and Cl atoms at atmospheric pressure G. Oksdath-Mansilla, A. B. Pe˝Ú˝ory, M. Albu, I. Barnes, P. Wiesen, M. A. Teruel Chemical Physics Letters 477 (2009) 22-27 (doi:10.1016/j.cplett.2009.06.035).
OH-Initiated degradation of unsaturated esters in the atmosphere: Kinetics in the temperature Range of 287-313 K M. B. Blanco, I. Bejan, I. Barnes, P. Wiesen, M. A. Teruel Journal of Physical Chemistry A 113 (2009) 5958-5965 (DOI: 10.1021/jp901755x).
Primary product distribution from the Cl-atom initiated atmospheric degradation of furan: Environmental implications Villanuev, F., Barnes, I., Monedero, E., Salgado, S., Gomez, M. V. and Martin, P. Atmospheric Environment 41 (2007) 8796-8810.
Investigations on the gas-phase photolysis and OH Radical kinetics of methyl-2-nitrophenols I Bejan, I Barnes, R Olariu, S Zhou, P Wiesen, Th Benter Physical Chemistry Chemical Physics 9 (2007) 5686-5692 (DOI: 10.1039/b709464g).
Reactions of NO3 radicals with limonene and ?-pinene: product and SOA formation M. Spittler, I. Barnes, I. Bejan, K. J. Brockmann, K. Wirtz Atmospheric Environment 40 Supplement 1, (2006) 116-127.
2.4. Access to the chamber under Eurochamp TA
Access to QUAREC is provided through Eurochamp-2 Transnational Access (TA) as outlined on the Eurochamp web site http://www.eurochamp.org/. The reactor can generally be made available for use at quite short notice. User own instrumentation can be attached to the reactor if found experimentally viable after consultation with the research facility responsible persons.
3. Institution in charge of the laboratory facility
3.1. Contact Information
Prof. Dr. Peter Wiesen, phone: +49 202 439 2515
Dr. Ian Barnes, phone: +49 202 439 2510University of Wuppertal
FB C - Department of Physical Chemistry
Gauss Strasse 20
D- 42119 Wuppertal, Germany
4. Additional Information