无负载纳米催化剂的研究进展

无负载金属硫化物催化剂因其本身即为硫化态,使用时不需要加入有毒的含硫化合物对加氢催化剂进行预硫化,并且具有超高的加氢脱硫能力而被关注。本文综述了无负载纳米硫化钼催化剂的制备技术、表征方法、脱硫机理等内容,并提出了进一步的研究方向。

Identification of the structure of Ni active sites for ethylene oligomerization on an amorphous silica-alumina supported nickel catalyst

The structure of Ni active sites supported on amorphous silica-alumina supports with different contents of Al_(2)O_(3)loadings in relation to their activities in ethylene oligomerization were investigated.Two kinds of Ni sites were detected by in situ FTIR-CO and H_(2)-TPR experiments,that are Ni^(2+)cations as grafted on weak acidic silanols and Ni^(2+)cations at ion-exchange positions.The ethylene oligomerization activities of these Ni/ASA catalysts were found an ascending tendency as the Al_(2)O_(3)loading decreased,which could be attributed to the enriched concentration of Ni^(2+)species on acidic silanols with a weaker interaction with the amorphous silica-alumina support.These Ni^(2+)species were more easily to be evolved into Ni^(+)species,which has been identified to be the active sites of ethylene oligomerization.Thus,it seems reasonable to conclude that Ni^(2+)species grafted on acidic silanols were the precursors of active sites.