煤焦油重油馏分加氢裂化反应动力学

Kinetics of hydrocracking for heavy coal tar oil

为考察煤焦油重油馏分加氢裂化反应动力学规律,在100 m L快速升温高压釜反应器内,采用高效分散铁系加氢裂化催化剂,在氢初压10 MPa、搅拌转速350 r/min、反应温度430~460℃时,进行了不同反应时间下新疆热解焦油>325℃重油馏分的加氢催化裂化反应试验。结果表明,焦油重油加氢裂化反应具有明显的连串反应特征,随转化率增加,氢耗、气产率、油产率逐渐增加,最大值分别为2.7%、8.3%和87.0%。随转化率增加,气产率选择性持续增加,油产率选择性先增加后降低,转化率57.2%时达到最大91.5%,说明连串反应后期,部分油产物继续裂解生成了气体产物,因此要控制反应深度。使用一级反应动力学模型很好地描述了焦油重油的催化加氢裂化反应特性,计算得到Ea=434.7 k J/mol,高于渣油的加氢裂化活化能。分散型的铁系催化剂起到了提供活化氢原子,稳定自由基进行的作用,焦油重油反应更多属于热活化过程。

To study the kinetics of hydrocracking for heavy coal tar oil, the experiments were carried out in a 100 mL high heating rate auto- clave reactor. Heavy Xinjiang coal tar oil was hydrocracked with highly dispersed Fe series catalyst in condition of hydrogen pressure 10 MPa, stirring speed 350 r/min, temperature 430-460℃, in different reaction time. Hydrocracking of heavy coal tar oil shows strong char- acter of sequential reaction. With the increase of tar oil conversion,hydrogen consumption and gas yield increase to 2.7% and 8.3% re- spectively, at the same time,oil yield increases to 87.0%. However, the gas selectivity increases constantly. In contrast, the oil selectivity reaches to the maximum 91.5% when the conversion is 57.2% ,and then decreases. It is thought that in later stage of sequential reaction, some oil product convertes into gas product. Thus, the proper reaction temperature and time are very important. The first order kinetics can fit the results of hydrocracking reaction for heavy coal tar oil well with Ea-- 434.7 kJ/mol, which is higher than many residuum hydrocrac- king reactions. The dispersed Fe catalyst can provide active H and stabilize radicals, and the hydrocracking of heavy coal tar oil is essen- tially thermal activation reaction.