Experimental study on co-pyrolysis of petroleum coke and coals: Synergy effects and co-gasification reactivity

In this work, the co-gasification reactions of petroleum coke and three Chinese coals were carried out using a thermogravimetric analyzer (TGA) to investigate the influences of blend ratio, coal rank, coal ash and coal char types (in situ formed char and preprepared char) on the synergy effects and co-gasification reactivities during co gasification. Due to the difference of particle size distribution, petroleum coke particles were filtered from blended chars and tested using a Raman spectrometer and a scanning electron microscopy combined with energy-dispersive X-ray spectroscopy (SEM-EDX). The results indicated that the gasification reaction rate of unreactive petroleum coke was enhanced through co-processing with low rank coals. For preprepared coal char, the catalytic effect of alkaline and alkaline earth metals (AAEMs) of coal ash was the main synergy effect. The in situ formed coal char presented a more significant synergy effect on the enhancement of reaction rate of petroleum coke, which was caused by the carbon structural changes of unreactive petroleum coke particles in co-pyrolysis process, such as less ordered carbon structure, lower graphitization degree, more amorphous carbon structure and more carbon active sites. Moreover, the SEM-EDX results also indicated that significant interactions existed during co-pyrolysis of petroleum coke char and in situ formed coal char.