Study on the characteristics and mechanism of fast co-pyrolysis of coal tar asphaltene and biomass

Co-pyrolysis of coal tar asphaltene (CTA) and biomass is one of the effective ways to realize the utilization of its resource. In this study, corn cob (CB), CTA and CB + CTA were heated to 700 ℃ at 600 ℃/min by TG and Py-GC/MS, respectively. In addition, the functional groups, the apparent morphology, the metal elements distributions and the phase changes were characterized by FTIR, SEM-EDS and Micro Melting Point Apparatus. The results showed that CB + CTA pyrolysis has a synergistic effect, which affected the pyrolysis process and changed the product distribution. In addition, the reaction temperature range and the reaction type of new products were determined by the tar composition distributions during multi-step pyrolysis. The kinetic results of reaction order 1, 2, 3 and 4 showed that the reaction was promoted at low temperatures and inhibited at high temperatures. During the co-pyrolysis process, CTA softened CB by heating, which affected the mass transfer and inhibited the escape of light volatiles from CB, therefore, the reaction temperature and the peak temperature of the maximum weight loss rate move to the high temperature region. Coal tar asphaltene (CTA), corn cob (CB) and CB + CTA were fast pyrolyzed by TG and Py-GC/MS, and single-step and multi-step pyrolysis products distribution and pyrolysis kinetics of CB, CTA, CB + CTA were studied. FTIR were used to characterize the functional groups of three raw materials and their char products, SEM-EDS were used to characterize the apparent morphology and the metal element distribution. Micro melting point apparatus was used to characterize the phase changes of the samples. Based on the results above, a mechanism of "bubble pyrolysis" for CB + CTA co-pyrolysis was proposed. [Display omitted] •The co-pyrolysis of CB and CTA was fast pyrolyzed by TG and Py-GC/MS, respectively.•The products distribution of CB + CTA by single-step and multi-step pyrolysis were studied.•The phase analysis of CB + CTA was studied by Micro Melting Point Apparatus during the heating.•The existence of synergism was proved by pyrolysis product distribution, kinetic, etc.•The co-pyrolysis mechanism of asphaltenes involved is the “bubble pyrolysis”.