A Novel Radioisotope Method for Studying Catalytic Transformations over Alumina, H-ZSM-5 and H-Beta Zeolite Catalysts: Investigation of Conversion of ¹¹C-Labeled Methanol to ¹¹C-Labeled Dimethyl Ether and Hydrocarbons

Abstract

A novel radiochemical method for investigating the catalytic transformations of the ¹¹C-radioisotope labeled methanol over H-ZSM-5 and H-Beta zeolite catalysts has been introduced. The catalysis process was monitored by gamma detectors and the ¹¹C-labeled products were analyzed by radio-gas chromatography. The medium pore H-ZSM-5 and H-Beta zeolite catalysts were synthesized and characterized using X-ray powder diffraction, scanning electron microscope, nitrogen adsorption, X-ray fluorescency and FTIR spectroscopy. The investigations of ¹¹C-labeled product distributions and reaction mechanism of the conversion of [¹¹C]methanol over H-ZSM-5 and H-Beta zeolite catalysts have been elaborated in terms of structure and acidity of the catalysts. In microreactors the effect of natural carbon compounds from environment can be a disturbing effect for the detection of inactive carbon products. Applied radio detection method eliminates these disturbing effects and detects only ¹¹C-labeled compounds during the whole catalytic process. In the study of the transformations of carbon compounds, besides the well known ¹⁴C tracer technique and ¹³C MAS NMR spectroscopy investigation, the ¹¹C-method is a new, more sensitive and simple one to monitor the transformation of the starting ¹¹C-labeled compound by radio detectors (gamma detector) and for analyzing the ¹¹C-labeled products by radio-gas chromatography.