Production mechanism of high-quality carbon black from high-temperature pyrolysis of waste tire.

High-temperature pyrolysis of waste tires is a promising method to produce high-quality carbon black. In this study, carbon black formation characteristics were investigated during tire pyrolysis at 1000-1300 °C with residence times of < 1 s, 1-2 s, and 2-4 s. It is shown that with temperature increasing from 1000 °C to 1300 °C carbon black yield was increased from 10% to 27% with residence times of 2-4 s. Carbon black exhibited a core-shell nanostructure over 1100 °C and the graphitization degree was promoted with the temperature and residence time. While the mean particle diameter decreased with the temperature to 69 nm at 1300 °C and further increased by residence time. The molecular-level evolution from tire to initial carbon black was further revealed by reactive force field molecular dynamics simulations. Light oil, gas, and radicals were transformed to initial cyclic molecules and long carbon chains via carbon-addition-hydrogen-migration, H-abstraction-C2H2-addition, and radical-chain reactions, subsequently forming PAHs. The coupling of PAHs aliphatic side chains formed large graphene layers that gradually bent to fullerene-like cores and generated incipient carbon black. The process mechanism from volatiles evolution to carbon black was proposed, which may be helpful for obtaining high-quality carbon black from high-temperature pyrolysis of waste tires.

Characteristics, kinetics, infrared analysis and process optimization of co-pyrolysis of waste tires and oily sludge.

The ecology was severely harmed by waste tires (WT) and oily sludge (OS). The OS and WT combinations' co-pyrolysis features, synergistic effects, and gas products were studied using thermogravimetric-infrared spectroscopy (TG-FTIR). To study kinetics and optimize pyrolysis, the Coats-Redfern and response surface methods were used. The results revealed that the OS and WT co-pyrolysis has synergistic effects. The major pyrolysis temperature range and the pyrolysis residual rate increased as the heating rate increased, and the E of the reaction increased. The strength of small-molecular-gases precipitation was modified by increasing the ratio of WT to OS, which increased OS pyrolysis. CH4, CO2, CO, and H2O are the most common gas products. The minimum estimated E and residual amount were 40.599 kJ/mol and 39.33%, respectively, when the WT mixture ratio was 58.7% and the heating rate was 10 °C/min. All the study contributes basic data to the development of the treatment of OS and WT in collaboration.

Influence of physicochemical properties of metal modified ZSM-5 catalyst on benzene, toluene and xylene production from biomass catalytic pyrolysis.

Biomass catalytic pyrolysis with various metals (Zn, Fe, Ca, Ce and La) modified ZSM-5 catalysts were analyzed, in order to investigate the relationship between the physicochemical properties of catalysts and the benzene, toluene and xylene (BTX) products. Results revealed that the BTX products were positively correlated with the strong acid site contents of the catalysts. Appropriate amount (0.5-4 wt%) of loaded Zn species increased the strong acid site contents of the catalysts as well as BTX yields, and the highest yield of BTX was observed under Zn loading amount of 2 wt%. While excessive metal loading amount (10 wt%) decreased both the acidity and the physical properties of the catalyst, resulting in poor diffusion of reactants and products in the channel and decreased the BTX yield. It is recommended that ZSM-5 catalyst with higher strong acid site content and pore volume should be used for BTX production.