Molybdate anion pillared Mg-Al hydrotalcite as precursors for HDS catalysts - II. Adsorption and catalytic activity of MoS2/Mg(Al)O

The dispersion state and energy property of MoS2/Mg(Al)O were characterized by determination of adsorption capacity of oxygen, adsorption heat of thio phene and reaction dynamics parameters. It was testified that, the same as MoO3, MoS2 also dispersed as unimolecular layer on the surface of Mg (Al) O , and the threshold value is equal to 4.77 mu mol/m(2). It means that, afte r sulfidization of MoO3, the dispersion state of MoS2 kept unchanged as tha t of MoO3. The adsorption heat of thiophene on MoS2/Mg(Al)O varied with MoO 3 content as follows: Q(1)=23.2 similar to2.8kJ/mol (w(MoO3) = 6.02%similar to9.34%), Q(2)=15.5 similar to 16.1 kJ/mol (w(MoO3) = 11.89%similar to 15. 83%), and Q(3)approximate to 30.0 kJ/mol (w(MoO3)>21.65%). The variation re gularity for activation energy of thiophene HDS is the same as that of adso rption heat on MoS2/Mg(Al)O. Otherwise, the HDS activity on the catalyst in creased with MoO3 content through a maximum and then decreased.