Formation mechanism of solid product produced from co-pyrolysis of Pingdingshan lean coal with organic matter in Huadian oil shale

A mixture of Pingdingshan lean coal and acid-treated Huadian oil shale was co-pyrolyzed in a drop-tube fixed-bed reactor in the temperature range of 300℃–450℃.To reveal the formation mechanism of the solid co-pyrolysis product,changes in some physicochemical properties were investigated,using analysis by X-ray diffraction,X-ray photoelectron spectroscopy,scanning electron microscopy,pore analysis,thermogravimetry,and electron spin resonance.X-ray diffraction showed that the lattice plane spacing for the co-pyrolyzed mixture decreased from 0.357 nm to 0.346 nm and the average stacking height increased from 1.509 nm to 1.980 nm in the temperature range of 300°C–450°C,suggesting that pyrolysis treatment increased its degree of metamorphism.The amount of oxygen-containing functional groups and pore volume decreased with increasing temperature.Thermogravimetry and electron spin resonance results showed that synergistic effects occurred during the co-pyrolysis process.A formation mechanism for the solid product was proposed.Hydrogen-rich radicals generated from the pyrolysis of the oil shale were trapped by hydrogen-poor macromolecular radicals of the intermediate metaplast produced from coal pyrolysis,thereby increasing the yield of solid product.

A review on co-pyrolysis of coal and oil shale to produce coke

It has become the top priority for coking industry to rationally use and enlarge coking coal resources because of the shortage of the resources.This review focuses on the potential utilization of oil shale(OS)as a feedstock for coal-blending coking,in which the initial and basic step is pyrolysis.However,OS has a high ash content.If such OS is directly used for coal-blending coking,the coke product will not meet market demand.Therefore,this review firstly summarizes separation and beneficiation techniques for organic matter in OS,and provides an overview on coal and OS pyrolysis through several viewpoints(e.g.,pyrolysis process,phenomena,and products).Then the exploratory studies on co-pyrolysis of coal with OS,including co-pyrolysis phenom-ena and process mechanism,are discussed.Finally,co-pyrolysis of different ranks of coals with OS in terms of coal-blending coking,where further research deserves to be performed,is suggested.

Synthesis of coal tar pitch-derived heteroatom-doped porous carbon materials for aqueous zinc-ion hybrid supercapacitors

Zinc-ion hybrid supercapacitors (ZHSs), which combine the superiority of batteries and supercapacitors, will become a new development direction in the field of energy storage. The development of ZHSs with high capacity and high stability can be further promoted by heteroatom doping or structural modification of cathode materials. Herein, N,O,P co-doped porous carbon materials were synthesized by a facile method using coal tar pitch as precursor, aluminum phosphate as template, and sodium hydroxide as activator. Due to the high specific surface area and abundant micropores, the heteroatom-doped porous carbon materials were employed as cathode for aqueous ZHSs to study the electrochemical performance. Benefitted from the rich micropores and heteroatom doping, the porous carbon electrodes exhibit an outstanding electrochemical performance and deliver a large specific capacitance of 113.3 mA h g􀀀 1 at 0.1 A g􀀀 1. In addition, the porous carbon electrode shows a high energy density of 64.9 Wh kg􀀀 1 and a high power density of 1.23 kW kg􀀀 1, which outperforms most aqueous ZHS energy storage systems previously reported. Interestingly, after 5000 cycles at 1 A g􀀀 1, the specific capacity is about 36% higher than the original capacity and the coulomb efficiency still remains nearly 100%. The article may provide a new insight into exploring cathode materials for high-performance aqueous rechargeable zinc-ion energy storage devices.