Experiments on thiophene pyrolysis using gas-phase Raman spectroscopy

Recent studies have demonstrated the capability of floating catalyst chemical vapor deposition (FC-CVD) synthesis to continuously produce direct-spun carbon nanotube (CNT) fibers with useful properties. Insufficient knowledge of chemical processes underpinning CNT growth via FC-CVD, due to lack of in situ measurements, remains a major limitation in understanding how to intensify the production of high-quality material. Thiophene is a key precursor to the formation of CNTs in H2 gas environments. A pulsed, gas phase laser Raman spectroscopy system was implemented to perform measurements of thiophene concentrations and mixture temperatures during the CNT synthesis process via FC-CVD in a cross flow reactor. From these measurements, it was possible to evaluate thiophene thermal decomposition at reactor temperatures between 20 and 1100 °C, as well as Raman signatures of the main products of thiophene decomposition. These measurements represent the first in situ Raman measurements performed in a FC-CVD CNT synthesis reactor.