沥青质在渣油加氢催化剂中的扩散研究

发布时间：2019-07-04 12:08

【摘要】：沥青质的吸附和沉积是造成加氢催化剂结焦最主要的原因,故其在催化剂中扩散方面的研究日益受到重视。本文以塔河常压渣油的沥青质为原料,甲苯为溶剂进行了扩散实验。扩散实验在不同实验条件下进行,并使用MATLAB软件编写程序,将实验数据和扩散模型拟合得到各个参数值,考察不同反应条件对沥青质聚集体在加氢催化剂中有效扩散系数的影响。将实验数据和已知参数结合扩散受阻有关方程计算扩散受阻因子,以考察不同实验条件下的扩散受阻因子和沥青质在不同催化剂中的扩散受阻程度。不同实验条件下,沥青质在加氢催化剂中的有效扩散系数受到不同程度的影响。有效扩散系数随溶液初始浓度的增加而减小,而且减小的幅度明显降低;延长操作时间,有效扩散系数逐渐减小,并且减小的速度越来越快;当催化剂孔径减小时,有效扩散系数减小,而且,由于沥青质聚集体在催化剂中的扩散受催化剂孔径的影响较大,使得有效扩散系数随孔径变化的幅度较大。随着操作时间的增加,催化剂孔道堵塞越来越严重,阻碍了沥青质聚集体的进一步扩散,使有效扩散系数逐渐减小,在相同扩散时间内,沥青质渗透深度增加的速度逐渐减小。沥青质在加氢催化剂中的扩散受阻因子受到不同实验条件的影响。随着溶液初始浓度的增加,沥青质在加氢催化剂孔道中扩散时的受阻程度增加,结合扩散实验数据和相应数学模型计算出的扩散受阻因子减小。延长扩散时间,沥青质聚集体在催化剂表面和孔道中的吸附和沉积越来越严重,则催化剂孔径和孔隙率减小,导致沥青质聚集体在催化剂中的扩散受阻因子减小。催化剂孔径越小,沥青质聚集体在催化剂中的扩散受阻程度越大,则扩散受阻因子越小。沥青质聚集体在平均孔半径为4.7nm的催化剂中的扩散受到严重阻碍,其扩散受阻因子F(λ)值非常小。
文内图片：

图片说明：沥青质单元结构
[Abstract]:The adsorption and deposition of asphaltene are the most important reasons for coking of hydrogenation catalysts, so more and more attention has been paid to the diffusion of asphaltenes in catalysts. In this paper, the asphaltene of Tahe atmospheric residue was used as raw material and toluene as solvent. The diffusion experiment was carried out under different experimental conditions, and the experimental data and diffusion model were fitted with MATLAB software to obtain each parameter value, and the effect of different reaction conditions on the effective diffusion coefficient of asphalt aggregates in hydrogenation catalyst was investigated. The diffusion blocking factor was calculated by combining the experimental data with known parameters with the equation of diffusion hindrance in order to investigate the diffusion blocking factor and asphaltene diffusion blocking degree in different catalysts under different experimental conditions. Under different experimental conditions, the effective diffusion coefficient of asphaltene in hydrogenation catalyst is affected to varying degrees. The effective diffusion coefficient decreases with the increase of the initial concentration of the solution, and the effective diffusion coefficient decreases with the increase of the initial concentration of the solution. When the pore size of the catalyst decreases, the effective diffusion coefficient decreases. Moreover, the effective diffusion coefficient varies greatly with the pore size of the catalyst because the diffusion of asphalt aggregates in the catalyst is greatly affected by the pore size of the catalyst. With the increase of operation time, the pore blockage of catalyst becomes more and more serious, which hinders the further diffusion of asphaltene aggregates, and the effective diffusion coefficient decreases gradually, and the rate of increase of asphaltene penetration depth decreases gradually in the same diffusion time. The diffusion blocking factor of asphaltene in hydrogenation catalyst is affected by different experimental conditions. With the increase of the initial concentration of the solution, the degree of hindrance of asphaltene diffusion in the pore of hydrogenation catalyst increases, and the diffusion hindrance factor calculated by combining the diffusion experimental data and the corresponding mathematical model decreases. When the diffusion time is prolonged, the adsorption and deposition of asphaltene aggregates on the surface and pores of the catalyst become more and more serious, and the pore size and porosity of the catalyst decrease, which leads to the decrease of the diffusion hindrance factor of the asphaltene aggregates in the catalyst. The smaller the pore size of the catalyst is, the greater the degree of diffusion hindrance of asphaltene aggregates in the catalyst is, the smaller the diffusion blocking factor is. The diffusion of asphalt aggregates in catalysts with average pore radius of 4.7nm is seriously hindered, and the diffusion blocking factor F (位) is very small.
【学位授予单位】：中国石油大学(华东)
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TE624.9

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