40
in the support. Based on the testing of prepared catalysts for VGO HDT application,
it was observed that B introduction into the impregnation solution decreased the
activity due to the formation of bulk BO 3 particles and small decline in the amount
of Mo on the catalyst surface in the form of Mo4+ while the addition of phosphorous increased the catalytic activity. Simultaneous introduction of both phosphoric
and boric acids into the impregnating solution increased the catalyst activity through
an increase in the number of MoS 2 layers in the slab.
Li et al. [14] showed higher HDS and HYD activity for NiMo-Al 2 O 3 catalysts
prepared using citric acid due to an increase in active NiMoS phase and morphology
control of MoS 2 phase. Higher catalytic activity was observed when Ni was complexed with CA preferentially before Mo in the impregnation solution. Also, CA has
not shown any promotional effect within the monometallic Mo/Al 2 O 3 catalyst.
Xia et al. [15] prepared CoMo/γ-Al 2 O 3 catalysts with different loadings of additives (Ce and/or P) to investigate the effect of Ce and P modifications on the catalyst
for the HDS of FCC gasoline. Phosphorous addition could slightly increase the
stacking number of MoS 2 by reducing MSI. Addition of cerium to the small amount
of 1.75 wt% could increase average slab length and stacking number apart from
providing Brønsted acidity to the support with the net effect of increasing the catalytic activity for HDS of thiophene and isomerization of olefins. They showed the
highest thiophene HDS and olefin isomerization conversions of 98.58% and 19.51%,
respectively, for the catalyst modified with both cerium and phosphorus exhibiting
the synergistic effect of Ce and P for the HDS of FCC gasoline with minimum
octane loss. The octane loss is minimized due to high olefin isomerization activity
of the catalyst, which is beneficial for removal of sulfur from FCC gasoline by
retaining the octane number.
Saleh et al. [16] investigated the effect of boron addition on the HDS activity of
CoMo/γ-Al 2 O 3 catalyst with varied boron contents and reported optimum boron
concentration of about 5 wt% for higher activity for the HDS of DBT.
Mendoza-Nieto et al. [17] studied the effect of CA addition on trimetallic
NiMoW catalysts prepared using different supports such as conventional γ-Al 2 O 3
and mesoporous SBA-15 for the HDS of DBT and 4,6-DMDBT. Their study showed
higher dispersion of active metals and better HDS activity using CA for SBA-15based trimetallic catalysts compared to conventional alumina-based catalysts, highlighting the dependence of support on the additive effect of CA during the preparation
of trimetallic hydrotreating catalysts. The citric acid effect is less when the metal–
support interaction is strong as in the case of γ-Al 2 O 3 -based NiMoW catalysts,
while the improved catalytic performance was obtained for the SBA-15-based catalyst due to lower MSI.
Vatutina et al. [18] studied different ways of addition of P to the CoMo-based
HDT catalyst during the synthesis and found that the addition of the precursor of P
into the impregnation solution resulted in an increase in HDS activity of DBT compared to other methods of P addition due to change in the active phase structure,
increase in the stacking number of active species, and decrease in MSI. Other methods of P addition such as the addition of P into the kneading paste or by
G. Valavarasu and B. Ramachandrarao
in the support. Based on the testing of prepared catalysts for VGO HDT application,
it was observed that B introduction into the impregnation solution decreased the
activity due to the formation of bulk BO 3 particles and small decline in the amount
of Mo on the catalyst surface in the form of Mo4+ while the addition of phosphorous increased the catalytic activity. Simultaneous introduction of both phosphoric
and boric acids into the impregnating solution increased the catalyst activity through
an increase in the number of MoS 2 layers in the slab.
Li et al. [14] showed higher HDS and HYD activity for NiMo-Al 2 O 3 catalysts
prepared using citric acid due to an increase in active NiMoS phase and morphology
control of MoS 2 phase. Higher catalytic activity was observed when Ni was complexed with CA preferentially before Mo in the impregnation solution. Also, CA has
not shown any promotional effect within the monometallic Mo/Al 2 O 3 catalyst.
Xia et al. [15] prepared CoMo/γ-Al 2 O 3 catalysts with different loadings of additives (Ce and/or P) to investigate the effect of Ce and P modifications on the catalyst
for the HDS of FCC gasoline. Phosphorous addition could slightly increase the
stacking number of MoS 2 by reducing MSI. Addition of cerium to the small amount
of 1.75 wt% could increase average slab length and stacking number apart from
providing Brønsted acidity to the support with the net effect of increasing the catalytic activity for HDS of thiophene and isomerization of olefins. They showed the
highest thiophene HDS and olefin isomerization conversions of 98.58% and 19.51%,
respectively, for the catalyst modified with both cerium and phosphorus exhibiting
the synergistic effect of Ce and P for the HDS of FCC gasoline with minimum
octane loss. The octane loss is minimized due to high olefin isomerization activity
of the catalyst, which is beneficial for removal of sulfur from FCC gasoline by
retaining the octane number.
Saleh et al. [16] investigated the effect of boron addition on the HDS activity of
CoMo/γ-Al 2 O 3 catalyst with varied boron contents and reported optimum boron
concentration of about 5 wt% for higher activity for the HDS of DBT.
Mendoza-Nieto et al. [17] studied the effect of CA addition on trimetallic
NiMoW catalysts prepared using different supports such as conventional γ-Al 2 O 3
and mesoporous SBA-15 for the HDS of DBT and 4,6-DMDBT. Their study showed
higher dispersion of active metals and better HDS activity using CA for SBA-15based trimetallic catalysts compared to conventional alumina-based catalysts, highlighting the dependence of support on the additive effect of CA during the preparation
of trimetallic hydrotreating catalysts. The citric acid effect is less when the metal–
support interaction is strong as in the case of γ-Al 2 O 3 -based NiMoW catalysts,
while the improved catalytic performance was obtained for the SBA-15-based catalyst due to lower MSI.
Vatutina et al. [18] studied different ways of addition of P to the CoMo-based
HDT catalyst during the synthesis and found that the addition of the precursor of P
into the impregnation solution resulted in an increase in HDS activity of DBT compared to other methods of P addition due to change in the active phase structure,
increase in the stacking number of active species, and decrease in MSI. Other methods of P addition such as the addition of P into the kneading paste or by
G. Valavarasu and B. Ramachandrarao