X射线衍射测定焦炭微晶有序度的研究

Study on the degree of microcrystalline order of coke determined by XRD

由于焦炭是由微晶碳和无定型碳组成的炭材料,其微晶结构的排列有序度决定着焦炭的物理化学性质,因此焦炭微晶结构的排列有序度的正确计算有助于焦炭性质的研究。针对焦炭X射线衍射(XRD)图谱中衍射峰峰型产生不对称、宽化和峰位角偏移的情况,通过实验研究改进焦炭微晶有序度的计算方法。通过对不同热处理温度焦炭的XRD分析计算其微晶结构参数,修正了基于(002)晶面间距计算焦炭有序度公式中d max的数值,即将d max改为3.894以避免结果出现负值。提出1种基于(002)衍射峰半高宽计算的焦炭微晶有序度的方法,该方法较基于(002)晶面的相邻网状平面间距(d 002)计算的焦炭微晶有序度(P d002)的方法更为合理,且按照此方法分析的焦炭微晶有序度与其反应活性相关,能够表征焦炭的反应性指数。

Coke is a kind of carbon material mainly composed of microcrystalline carbon and amorphous carbon.The ordering degree of coke microcrystalline structure determines the physical and chemical properties of coke.Therefore,the correct calculation of the ordering degree of the coke microcrystal structure is helpful to research coke properties.Regarding to the problems in XRD spectrum such as diffraction peak shape asymmetry,broadening and peak angular shift,this paper improved the calculation method of microcrystalline order of coke through experimental research.XRD analysis of coke at different heat treatment temperatures was carried out to calculate its microcrystalline structure parameters,d max in the formula of coke order degree calculated based on(002)crystal plane spacing was modified to 3.894 to avoid negative results.A method was proposed for calculating the degree of ordering of coke crystallites based on the half-width value of(002)diffraction peak.This method is more reasonable than the method based on the degree of coke crystallinity calculated from the adjacent mesh plane spacing of the(002)crystal plane.The degree of order of the coke crystallites analyzed in accordance with this method correlates with its reactivity,which can characterize the reactivity index of the coke.