24
Zhang et al. [72] prepared NiMo HDS catalysts with different crystal forms of
alumina using AlCl 3 ·6H 2 O and Al (NO 3 )·9H 2 O as alumina sources and studied their
catalytic performance for FCC diesel hydrodesulfurization. They reported the HDS
efficiencies to be of the order: NiMo/δ-Al 2 O 3 > NiMo/γ-Al 2 O 3 > NiMo/θ-Al 2 O 3 .
The higher HDS and HDN activities for FCC diesel in the case of NiMo/δ-Al 2 O 3
were attributed to the concentrated pore size distribution, moderate MSI, and the
highest sulfidation degree.
Gao et al. [73] synthesized γ-alumina-supported MoS 3 nanoparticles (MoS 3 /
Al 2 O 3 ) by a chemical deposition method and later prepared pre-sulfided bimetallic
HDS catalysts through Ni promotion. Use of MoS 3 as a precursor enabled better
nickel promoter decoration onto the edges of MoS 2 nanoslabs forming Type II sites
and higher sulfidation degree that resulted in higher HDS activity.
CoMoS catalysts supported on mesostructured titania were studied for HDS of
4,6-DMDBT by Naboulsi et al. [74], and results were compared with conventional
alumina-supported catalysts. The mesostructured titania-supported catalyst was
found to favor the DDS pathway, which was attributed to the intrinsic acidic properties (both Lewis and Brönsted acidities) of the supports retained even after the
impregnation of Co and Mo, arising from the coexistence of both phases.
Asadi et al. [75] reported a novel method for synthesis of nano pseudoboehmite
powders with varying textural properties based on CO 2 -assisted neutralization of
NaAlO 2 aqueous solution in a semi-batch membrane microreactor. Later, the
nanopowders were utilized to prepare a number of nano γ-Al 2 O 3 supports as well as
supported NiMo catalysts with varied average pore sizes and investigated the effect
of catalyst pore size on HDS performance using straight-run gas oil and its blend
with cracked gas oil. The highest HDS was obtained using catalysts with the average pore size of 8.0 (5.9) and 9.1 (7.2) nm, respectively, for both feedstocks. The
study highlighted the significance of the pore size on the HDS activity of the catalyst and the novel synthesis of mesoporous γ-Al 2 O 3 supports with a controlled average pore size of up to 20 nm.
Xie et al. [76] reported the synthesis of novel composites made from monodispersed porous Al-glycolate spheres (NiMo/Al-SP) through alcoholysis or hydrolysis treatments as HDT catalysts and tested their performance for HDS of DBT and
HYD of naphthalene. The novel catalyst showed 71.22% DBT and 88.28% naphthalene conversion at 270 °C temperature, 5 MPa initial H 2 pressure, and 10 h reaction time.
Valles et al. [77] reported iridium-based catalysts as alternatives for conventional
CoMo/Al 2 O 3 or NiMo/Al 2 O 3 catalysts for HDT application. They studied the HDS,
HDN, and hydrogenation activities of iridium catalysts supported on different zirconium-modified SBA-15 supports using model compounds. The sol-gel method was
used to synthesize zirconium-modified SBA-15 supports using two sources of zirconium, zirconyl chloride, and zirconium (IV) propoxide with lactic acid as the
coordinating ligand. Zirconium is mainly present as tetrahedral Zr4+ species and
provides better dispersion and reducibility of iridium active species apart from providing higher acidity to the catalyst. The catalyst synthesized using zirconium propoxide and lactic acid was found to be the most active catalyst for HYD of tetralin,
G. Valavarasu and B. Ramachandrarao
Zhang et al. [72] prepared NiMo HDS catalysts with different crystal forms of
alumina using AlCl 3 ·6H 2 O and Al (NO 3 )·9H 2 O as alumina sources and studied their
catalytic performance for FCC diesel hydrodesulfurization. They reported the HDS
efficiencies to be of the order: NiMo/δ-Al 2 O 3 > NiMo/γ-Al 2 O 3 > NiMo/θ-Al 2 O 3 .
The higher HDS and HDN activities for FCC diesel in the case of NiMo/δ-Al 2 O 3
were attributed to the concentrated pore size distribution, moderate MSI, and the
highest sulfidation degree.
Gao et al. [73] synthesized γ-alumina-supported MoS 3 nanoparticles (MoS 3 /
Al 2 O 3 ) by a chemical deposition method and later prepared pre-sulfided bimetallic
HDS catalysts through Ni promotion. Use of MoS 3 as a precursor enabled better
nickel promoter decoration onto the edges of MoS 2 nanoslabs forming Type II sites
and higher sulfidation degree that resulted in higher HDS activity.
CoMoS catalysts supported on mesostructured titania were studied for HDS of
4,6-DMDBT by Naboulsi et al. [74], and results were compared with conventional
alumina-supported catalysts. The mesostructured titania-supported catalyst was
found to favor the DDS pathway, which was attributed to the intrinsic acidic properties (both Lewis and Brönsted acidities) of the supports retained even after the
impregnation of Co and Mo, arising from the coexistence of both phases.
Asadi et al. [75] reported a novel method for synthesis of nano pseudoboehmite
powders with varying textural properties based on CO 2 -assisted neutralization of
NaAlO 2 aqueous solution in a semi-batch membrane microreactor. Later, the
nanopowders were utilized to prepare a number of nano γ-Al 2 O 3 supports as well as
supported NiMo catalysts with varied average pore sizes and investigated the effect
of catalyst pore size on HDS performance using straight-run gas oil and its blend
with cracked gas oil. The highest HDS was obtained using catalysts with the average pore size of 8.0 (5.9) and 9.1 (7.2) nm, respectively, for both feedstocks. The
study highlighted the significance of the pore size on the HDS activity of the catalyst and the novel synthesis of mesoporous γ-Al 2 O 3 supports with a controlled average pore size of up to 20 nm.
Xie et al. [76] reported the synthesis of novel composites made from monodispersed porous Al-glycolate spheres (NiMo/Al-SP) through alcoholysis or hydrolysis treatments as HDT catalysts and tested their performance for HDS of DBT and
HYD of naphthalene. The novel catalyst showed 71.22% DBT and 88.28% naphthalene conversion at 270 °C temperature, 5 MPa initial H 2 pressure, and 10 h reaction time.
Valles et al. [77] reported iridium-based catalysts as alternatives for conventional
CoMo/Al 2 O 3 or NiMo/Al 2 O 3 catalysts for HDT application. They studied the HDS,
HDN, and hydrogenation activities of iridium catalysts supported on different zirconium-modified SBA-15 supports using model compounds. The sol-gel method was
used to synthesize zirconium-modified SBA-15 supports using two sources of zirconium, zirconyl chloride, and zirconium (IV) propoxide with lactic acid as the
coordinating ligand. Zirconium is mainly present as tetrahedral Zr4+ species and
provides better dispersion and reducibility of iridium active species apart from providing higher acidity to the catalyst. The catalyst synthesized using zirconium propoxide and lactic acid was found to be the most active catalyst for HYD of tetralin,
G. Valavarasu and B. Ramachandrarao