Proton NMR thermal scanning methods for the study of oil shale pyrolysis

Dynamic experimental techniques by which non-equilibrium states of a system can be observed during thermally induced transformations allow the kinetics of pyrolysis mechanisms to be directly studied. This paper reports on the novel use of simple low resolution Proton nuclear magnetic resonance (/sup 1/HNMR) measurements as a reaction time probe to monitor the state of oil shales during heating from room temperature to about870K. The method involves the observation of the /sup 1/HNMR transverse relaxation transient at regular intervals during heating. Similar studies of coal pyrolysis and a description of the apparatus used have been previously reported. In these reports, the ability to obtain non-equilibrium data during fossil fuel pyrolysis despite the limited scope for signal averaging and the deterioration of signal-to-noise of the /sup 1/HNMR signal with rise in temperature was demonstrated. The experiments reported here involved measurements of the /sup 1/HNMR during pyrolysis of shale specimens contained in open tubes and flushed with dry nitrogen gas so that volatile pyrolysis products were quickly removed. A number of different parameters extracted from the data are investigated for their usefulness in monitoring changes that occur in the properties of the specimen. These parameters relate to the loss of hydrogen frommore » the specimen and changes that occur in the molecular structure and mobility as a consequence of chemical and physical transformations. The results presented are not part of a systematic study of oil shale pyrolysis but rather those of various experiments selected to demonstrate the utility and potential of the method.« less