Research On The Controllable Preparation And Performance Of Coal Tar-based Foamed Carbon

Carbon foams as a novel kind of high-quality of carbon materials,have excellent electrical,magnetic,thermal,and mechanical properties due to its unique pore structures,which colud be widely used in potential application to the filed of of chemical industry,metallurgy,building,and aerospace.In this paper,based on rich resources of coal in China and on account of the composition of the precursors significantly affect the foaming process,carbon foams with different pore structures were prepared from tailored coal tar pitches via self-foaming and template methods.The mechanical,thermal insulation and oxidation resitance of carbon foams were investigated.The present work focuses on the controllable preparation of carbon foams derived from taiolerd the chemical compositions of coal tar pitches via heat treatment of low temperature coal tar.This research conclusion has certain directive significance for high-performance carbon foams prepared from CTP with low cost.The main research contents can be summarized as follows.1.Carbon foams with spherical and pentagonal dodecahedral pore were produced using coal tar pitches obtained from low-temperature coal tar,after thermo-treatment combined with selective solvents and gradient separation via self-foaming and carbonization.Experiment results showed that the composition of the precursors can be tailored by solvent,polymerization temperature,and removal of fractions.The contronallable preparation of carbon foams structure and properties can be achieved by the change of group component in coal tar pitches.The performance of carbon foam depends on the cell structure.The carbon foams with pentagonal dodecahedral pore structure show excellent thermal insulation performance(0.028 W?m^-1?K^-1).The compressive strength of carbon foams with spherical pore is as high as 6.580 MPa.The carbon foams also show good oxidation resistance performance at 1000?in air,owing to the lack of the transitional pore system of its pentagonal dodecahedron structures for oxidizing gas diffusion and then the oxidation pits and carbon sheath formed on the surface of carbon foams.2.The investigation of the relation between the formation mechanism of spherical and pentagonal dodecahedral pore of carbon foams and the pyrolysis and rheological behaviors,and release of gaseous products indicate,that the light component with aromatic C-H/alkane C-H/CO/CO₂ were form a core and then aggregated grow up and finally became stable pores in the influence of P_s and P_f.Meanwhile,Rates of change in viscosity were accounted for and found to have effect on both the growth and spherical and pentagonal dodecahedral behavior of the bubble during the foaming process.The aromatic C-H/alkane C-H and CO₂ could be formed spherical pore in molten coal tar pitch.3.Based on the pore structure depends on the chemical composition of coal tar pitch,carbon foams with honeycomb-type,pentagonal dodecahedral pore structures made of coal tar pitches have been successfully fabricated by using oxi-bamboo leaves as template and thermonuclear.The controllable preparation of carbon foams structure and properties can be achieved by the change of the addition of oxi-bamboo leaves.Honeycomb-type,open-cell structures and orderly lamellar ligaments exist in the carbon foams generated,which led to an increase in the thermal insulation coefficient.The lowest density(0.146 g·cm^-3)and thermal conductivity(0.059 w·m^-1·k^-1)were obtained in carbon foams containing 10.0 wt.%bamboo leaves.Comparison of other coal tar pitches-based foams,the carbon foams with pentagonal dodecahedral pore structures showed excellent thermal insulation.4.Three-dimensional micro/mesoporous C/N/O-droped carbon foams with slice structure were prepared from low temperature via template-salt gas method using nano-magnesium oxide as template,urea and ammonium citrate as auxiliary agents,KOH as activator.The contronallable preparation of carbon foams structure and properties can be achieved by adjusting the addition of auxiliary agents,carbonization hold time and activation temperature.The specific surface area of MCF_AC-CM-2-1000 was 671.1 m²?g^-1,and the specific surface area of micropores was 119.4 m²?g^-1,the total pore volume was0.56 cm³?g^-1,the micropore volume is 0.050 cm³?g^-1,and the mesoporous volume was0.50 cm³?g^-1,which was prepared by using urea and ammonium citrate as additives at carbonization for 2 h and then activated at 1000°C.The experimental results of different temperatures and different initial concentrations were simulated by the adsorption isotherm model in order to explore the adsorption mechanism.Results showed that MCF_AC-CM-2-1000 obtained a high adsorption apacity of Cd????151.73 mg/g?at 318 K.The adsorption isotherms and the kinetics were in agreement with the Langmuir isotherm model and the pseudo-second-order kinetic model.The process was both endothermic and spontaneous.Cd???-loading MCF_AC-CM-2-1000 could be successfully regenerated by the HCl and NaOH treatment.The MCF_AC-CM-2-1000 showed good potential for purifying wastewater.