Synergy between Mo/SiO₂and Co/SiO₂beds in HDS: a remote control effect?

EFFECT OF LIQUID SPATIAL VELOCITY ON M D [M D = Mn, Fe, Co, Ni, Cu AND Zn]//Mo SYNERGISM IN THE HYDRODESULPHURIZATION REACTION

“…From these studies it has been concluded that promotion via hydrogen spillover increases by decreasing reaction temperature 1,[4][5][6][7][8] ; decreasing the distance between D and A 5 ; decreasing the isoelectric point (IEP) of the material used as separator between both beds 5 ; avoiding discontinuity between D and A…”

“…In this model Co 9 S 8 and MoSx are called donor (D) and acceptor (A), respectively. Thus, the stacked [donor metal//separator//acceptor metal] bed is abbreviated as M D //M A and the [HDS (%) stacked bed/HDS (%) single bed] ratio was defined as the "spillover factor" and abbreviated Fso 1 . In that study Co/SiO 2 was located in the first bed; SiO 2 in the second bed (as separator), and Mo/SiO 2 in the third bed.…”

Tungsten and Rhenium as Hydrogenation Agents in the Hydrodenitrogenation of Pyridine Using Stacked Bed Catalyst Systems

“…Valdebenito et al 17 worked with stacked bed systems in the HDN of pyridine, proving that it is possible to achieve this process through the formation of hydrogen spillover (Hso), generating an effect similar to that observed for the HDS reaction [18][19][20][21][22][23] . This proposal is based on prior work by Ojeda et al 24 , who give direct proof of the hydrogen spillover effect, under conditions similar to those used in industry, and using gas oil as the feed source. This study reported the existence of synergism in the stacked bed systems of Co/SiO 2 //SiO 2 //Mo/SiO 2 (donor//separator//acceptor), where the donor and the acceptor were separated using the amount of SiO 2 needed to create a distance of 5 mm between the two beds.…”

EFFECT OF FLUORINE IN THE SYNERGISM Co-Mo VIA HYDROGEN SPILLOVER ON THE HYDRODESUL-PHURIZATION OF REFRACTORY MOLECULES

“…This effect has been explained principally through two models, the Co-Mo-S 2 and the Remote Control model 3 . In our research group, the synergisms has been studied in experimental conditions in which only operated the remote control model [4][5][6][7][8][9][10][11] , that postulates that synergism is caused by the formation of an activated hydrogen specie called "hydrogen spillover" (Hso) in the Co sulphide surface, which migrates to the MoS 2 , increasing the amount of its active sites, without formation of any mixed phases like Co-Mo-S 12 . To meet the environmental specifications are required new catalysts that offer better activity and selectivity for hydrodesulphurization of sulphur refractory compounds -known as deep HDS-, and have greater tolerance to sulphur.…”

“…The Co/γ-Al 2 O 3 and Mo/γ-Al 2 O 3 catalysts were prepared by impregnation in excess of solvent using a rotary evaporator as in previous studies [4][5][6][7][8][9][10][11] . Once impregnated the samples were dried at 373 K for 12 h and calcined at 823 K for 4.5 h. The nominal metal contents are close to 1.6 atoms nm -2 for Co and 2.9 atoms nm -2 for Mo.…”