NiMoS/γ-Al2O3上二苯并噻吩加氢脱硫和喹啉加氢脱氮反应的相互影响

Mutual Influence of Hydrodesulfurization of Dibenzothiophene and Hydrodenitrogenation of Quinoline over NiMoS/γ-Al_2O_3 Catalyst

在固定床高压微反装置上,考察了预硫化型NiMoS/γ-Al2O3催化剂上二苯并噻吩(DBT)加氢脱硫(HDS)反应和喹啉加氢脱氮(HDN)反应之间的相互影响.结果表明,喹啉对DBT的HDS反应具有强烈的抑制作用,其中对加氢路径比氢解路径的抑制作用更强,这是由喹啉及其HDN反应的中间产物与DBT在活性位上的竞争吸附造成的.在300和340℃时,喹啉对DBT的HDS反应中氢解路径的抑制程度与其HDN中间产物的相对含量紧密相关.而DBT能够提高喹啉的脱氮能力,这源于其HDS产物H2S.H2S促进了催化剂表面硫阴离子空穴向B酸位的转化,从而提高了喹啉HDN中间产物分子的C(sp3)-N键的断裂能力.HDN活性相的保持不需要过多的硫原子.

Both the influence of quinoline on hydrodesulfurization （HI）S） of dibenzothiophene （DBT） and the effect of DBT on hydrodenitrogenation （HDN） of quinoline were studied over a presulfided NiMoS/γ-Al2O3 catalyst in a fixed-bed high pressure microreactor. The results suggested that quinoline could strongly inhibit the HDS reaction of DBT, where the inhibitory effect on the hydrogenation route （HYD） was stronger than that on the direct desulfurization route （DDS）, which resulted from the competitive adsorption of quinoline and intermediate products of HDN reaction on active sites. The different inhibitory extent of quinoline on the DDS route at 300 and 340 ℃ was closely related to the relative amount of HDN intermediate products. DBT had a positive influence on hydrodenitrogenation ability, which was due to H2S released in the HDS reaction. H2S promoted the conversion of coordinatively unsaturated sites to Brcnsted acid sites on the catalyst surface, which in turn facilitated C（sp^3）-N bond cleavage of the HDN intermediate molecules. Although the formation of active sites for HDN must be in the presence of S, the maintenance of active sites does not need too much S.