介孔氧化铝制备方法对其载体及催化剂性能的影响

Influences of preparation methods of mesoporous alumina on its properties and performances of the catalysts

分别采用醇铝法和沉淀法制备氧化铝,借助N_2物理吸附-脱附、XRD和SEM等技术对试样进行了表征,并对制备的载体进行对比。表征结果显示,醇铝法制备的拟薄水铝石纯度及结晶度更高,杂质少;小孔氧化铝孔径分布峰集中且峰形尖锐,峰宽较窄;大孔氧化铝孔径分布峰更宽甚至消失;氧化铝由粒径均匀且完整度高的球形颗粒聚集而成;小孔氧化铝载体孔径分布集中,没有大孔;而大孔氧化铝载体除介孔外还含有许多大孔。将两种方法制得的大孔氧化铝载体制备成催化剂,以渣油和蜡油混合油为原料,在氢分压15.5 MPa、氢油体积比650∶1、反应温度390℃、液态空速0.5 h^(-1)的条件下对催化剂进行评价。评价结果显示,醇铝法制备的催化剂具有较为优异的加氢脱硫、加氢脱氮、加氢脱残炭及加氢脱金属活性。

Alumina samples were prepared by aluminium alkoxide method and precipitation method separately,and characterized by means of N3-TPD,XRD and SEM. The results showed that,the pseudo boehmite samples prepared by the aluminium alkoxide method had high purity,high crystallinity and low impurity content;the pore size distribution of alumina with micropore was narrow;and the pore size distribution of macroporous alumina was wider and even disappeared. The prepared alumina samples consisted of spherical particles with uniform particle size. The pore size distribution of the alumina supports with micropores was concentrated without macropores,and there were many macropores and mesopores in the macroporous alumina supports. Catalysts were prepared from the macroporous supports prepared by the two methods,and their activity were evaluated under the conditions of residual oil and wax oil as raw materials,hydrogen partial pressure 15.5 MPa,volume ratio of hydrogen to oil 650 ∶ 1,reaction temperature 390 ℃ and volume space velocity 0.5 h-1. The results showed that the catalyst prepared by the aluminium alkoxide method had much higher activity in hydrodesulfurization,hydrodenitrogenation,hydrode-carbon residue and HD（Ni＋V）.