Radioisotopic tracing of methanol transformation using 11C-labelled methanol over copper ion-exchanged H-ZSM-5, H-Beta and H-MCM-41

摘要

Short half-life 11C-radioisotope tracer in methanol form was used to study the transformation of methanol over copper ion-exchanged H-ZSM-5, H-Beta and H-MCM-41 catalysts. The progresses of adsorption and desorption as well as methanol transformation were followed by radiodetection. The reaction products were analyzed by radio-gas chromatography. The GC analysis was completed with a radiodetector that could distinguish the radiolabelled derivates from other non-radioactive compounds, reagents or impurities. The radiodetector can be more sensitive to detect smaller amount of compound than the thermal conductivity detector or flame ionization detector since the intensity of a radio-signal is independent on thermal conductivity or ionization energy of compounds. The copper introduction into the catalysts had an inhibitory effect on the reaction to proceed further from the equilibration with the methanol and dimethyl ether resulting in hydrocarbons C3–C6. Presence of copper also allowed a possible reaction route for methanol to give formaldehyde and methyl formate.