The PTFE and PFA tubes with an outer diameter of 1/4 inch are both cut to a length of 30 cm and the ends reinforced with tubing inserts (Swagelok) to allow gas tight ferrule fittings. The upstream end of the reactor is capped with a tee-piece with an 1/16 inch sealed tube containing a moveable K-type thermocouple, passing through the whole length of the tube and the gas-inlet. The reactor tube is heated with an aluminum jacked with four heating cartridges placed in it, one of which is equipped with an internal K-type thermocouple to control the temperature. A second thermocouple is placed in a 1 mm kerf in the heating jacked as to be in contact with the outer tube wall. The third K-type thermocouple is placed in the 1/16 inch sealed tube at the height of the catalyst bed to be able to measure the inner reactor temperature. A sketch of the setup is shown in Figure ). From bottom (downstream) to top the tube is first filled with 400 mg of quartz beads in the size fraction of 0.5-0.75 mm framed with silica wool to stabilize the catalyst bed and distribute the gas flow.