微型流化床中萘裂解生成小分子气体的反应动力学研究

Gasification is one of the effective ways for the high-value utilization of coal, biomass and other carbon-containing fuels. In order to investigate the reaction conversion characteristics of tar during the gasification process, naphthalene was selected as a tar model compound, and the fluid catalytic cracking (FCC) catalyst and lignite pyrolysis coke were used as the contact cracking carriers. The law of naphthalene catalytic cracking reaction under fluidization conditions was investigated by using a micro-fluidized bed, and the kinetic parameters of typical gas components such as CH_4 and H2 generated by naphthalene cracking were calculated by the Friedman method and the integral method. The results show that both the FCC catalyst and the lignite coke have obvious catalytic effects on naphthalene cracking, and the overall value of the reaction activation energy for naphthalene cracking by the lignite coke is lower than that of the FCC catalyst. The generation of H2 from naphthalene cracking by the FCC catalyst conforms to the three-dimensional diffusion (spherical symmetry) model, and the generation of CH_4 conforms to the nucleation and growth (n = 2/3) model. Correspondingly, the generation of H2 and CH_4 from the reaction of naphthalene cracking by the lignite coke has a better fitting degree when the shrinking geometry (cylindrical symmetry) and three-dimensional diffusion (cylindrical symmetry) are adopted respectively.

气化是煤、生物质以及其他含碳燃料高值化利用的有效途径之一。为了考察气化过程中焦油的反应转化特性,选取萘作为焦油模型化合物,以流化催化裂化(fluid catalytic cracking,FCC)催化剂及褐煤热解焦作为接触裂解载体,利用微型流化床考察流化条件下萘催化裂解反应规律,并采用Friedman法和积分法计算萘裂解生成CH_4和H2等典型气体组分的动力学参数。结果表明,FCC催化剂与褐煤焦均对萘裂解有明显的催化效果,褐煤焦用于萘裂解的反应活化能整体数值低于FCC催化剂。FCC催化剂裂解萘生成H2符合三维扩散(球形对称)模型,生成CH_4符合成核与生长(n=2/3)模型。相应地,褐煤焦裂解萘反应生成H2和CH_4分别采用收缩几何形状(圆柱形对称)和三维扩散(圆柱形对称)具有较好的拟合度。