Performance of carbon foams based on heavy tar produced by tar-rich coal pyrolysis
[Objective]Preparing graphitized foam materials using heavy tar produced by the pyrolysis of tar-rich coals plays a significant role in the high-value utilization of tar-rich coal resources.[Methods]This study aims to prepare high-performance carbon foam materials by investigating the relationships between various reaction conditions and carbon foam performance.First,using mesophase asphalt prepared with heavy tar as the precursor,carbon foams were de-veloped via the high-temperature self-foaming method.Then,the effects of different reaction temperatures,heating rates,and reaction pressures on the performance of coal tar-based carbon foams were examined.Finally,quadratic multinomi-al regression equations were established using Box-Behnken response surface experiments,revealing the relationships of the porosity and thermal conductivity of the carbon foams with various reaction conditions.[Results and Conclusions]The experimental results indicate that the reaction temperature,heating rate,and reaction pressure significantly influ-ence the performance of coal tar-based carbon foams.The optimal porosity of the carbon foams was 72.8%,correspond-ing to a temperature of 559℃,a pressure of 0.48 MPa,and a heating rate of 9℃/min.In this case,the effects of these reaction conditions decreased in the order of temperature,pressure,and heating rate.The optimal thermal conductivity value of the carbon foams was 0.219 W/(m·K),corresponding to a temperature of 549℃,a pressure of 2 MPa,and a heating rate of 3.9℃/min.In such an instance,the effects of these factors decreased in the order of heating rate,pres-sure,and temperature.The process parameters optimized using the response surface model enable the preparation of car-bon foam materials with high porosity and thermal conductivity,providing a new solution for enhancing the pyrolysis ef-ficiency of tar-rich coals.
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