Transformation of a model FCC gasoline olefin over transition monometallic sulfide catalysts

The selective HDS of FCC gasoline is a sensible option for reducing sulfur content in commercial gasoline. For such application, a minimum activity of the catalyst toward olefin hydrogenation is required to preserve the high octane number of the feedstock. The conversion of a model FCC olefin (2,3-dimethylbut-2-ene:23DMB2N) under close HDS conditions was investigated over a series of unsupported transition monometallic sulfides (FeS, Ni3S2, PdS, Co9S8, Rh2S3, RuS2, PtS, and MoS2). The results reveal for the first time that a volcano curve relationship exists between the ab initio calculated sulfur–metal bond energy, image, descriptor of bulk TMS, and their activities in olefin hydrogenation under the conditions of HDS of FCC gasoline. In particular, Rh2S3, with an intermediate metal sulfide bond energy of 119 kJ/mol, was the most active catalyst in hydrogenation of the model olefin. In a similar spirit as volcano curves obtained for the HDS of dibenzothiophene and hydrogenation of toluene and recently reported in the literature, a microkinetic model furnished a rational interpretation of this trend.