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本文研究了烃类蒸汽转化催化剂Ni/α-Al_2O_3 经高温水热处理(987K,H_2O/H_2 为7.5)后,平均镍晶粒度的变化及其对催化剂抗结碳性能的影响规律。实验证明,镍晶粒随水热处理时间的增加先是熔结长大,当水热处理足够长时间后,镍晶粒产生再分散。其积碳速率与镍晶粒大小的变化完全相适应。将La_2O_3 加入催化剂后可以显著提高镍在载体表面上的分散度,从而提高催化剂的抗碳性能。将La_2O_3和BaO同时加入Ni/α-Al_2O_3 催化剂时,在水热处理条件下所产生的 LaAlO_3和尖晶石结构的BaAl_2O_4,能促进金属颗粒在载体表面上的铺展,并阻止晶粒的熔结长大,使镍晶粒的再分散作用更为明显。
In this paper, the change of average grain size of Ni / α-Al_2O_3 after hydrothermal treatment (987K, H_2O / H_2 = 7.5) at high temperature was studied, and its effect on the anti-caking property of the catalyst was studied. Experiments show that, with the increase of hydrothermal treatment time, the nickel grains grow and melt first. When the hydrothermal treatment is long enough, the nickel grains are redispersed. The carbon deposition rate is completely compatible with the change of nickel grain size. La 2 O 3 added to the catalyst can significantly improve the dispersion of nickel on the surface of the carrier, thereby enhancing the carbon resistance of the catalyst. When both La 2 O 3 and BaO are added to Ni / α-Al 2 O 3 catalyst, LaAlO 3 and spinel-structured BaAl 2 O 4 generated under the hydrothermal treatment can promote the spreading of the metal particles on the surface of the support and prevent the fusion of the grains Large, so that the redispersion of nickel grains more obvious.