Silica supported amorphous molybdenum catalysts prepared via sol–gel method and its catalytic activity

Adam, Farook; Iqbal, Anwar

doi:10.1016/j.micromeso.2010.10.037

Cited by 43 publications

(26 citation statements)

References 31 publications

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“…The band at approximately

\overset{ν}{true}

=1637 cm −1 is due to the bending vibration of trapped water molecules. The broad band around

\overset{ν}{true}

=3442–3456 cm −1 is due to the HO−H vibration of water molecules adsorbed on the silica surface and the stretching vibration of SiO−H bonds . The FTIR spectra of bulk H 3 PMo 12 O 40 × x H 2 O shows bands at

\overset{ν}{true}

=1065, 962, 871, and 784 cm −1 which can be assigned to stretching vibrations ν as (P−O d ), ν as (Mo−O t ), ν as (Mo‐O b ‐Mo), and ν as (Mo‐O c ‐Mo), respectively.…”

Section: Resultssupporting

confidence: 91%

Catalyst Development for the Synthesis of Ozonides and Tetraoxanes Under Heterogeneous Conditions: Disclosure of an Unprecedented Class of Fungicides for Agricultural Application

Yaremenko

Radulov

Belyakova

et al. 2020

Chemistry A European J

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The catalyst H3+xPMo12−x+6Mox+5O40 supported on SiO2 was developed for peroxidation of 1,3‐ and 1,5‐diketones with hydrogen peroxide with the formation of bridged 1,2,4,5‐tetraoxanes and bridged 1,2,4‐trioxolanes (ozonides) with high yield based on isolated products (up to 86 and 90 %, respectively) under heterogeneous conditions. Synthesis of peroxides under heterogeneous conditions is a rare process and represents a challenge for this field of chemistry, because peroxides tend to decompose on the surface of a catalyst . A new class of antifungal agents for crop protection, that is, cyclic peroxides: bridged 1,2,4,5‐tetraoxanes and bridged ozonides, was discovered. Some ozonides and tetraoxanes exhibit a very high antifungal activity and are superior to commercial fungicides, such as Triadimefon and Kresoxim‐methyl. It is important to note that none of the fungicides used in agricultural chemistry contains a peroxide fragment.

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“…The band at approximately

\overset{ν}{true}

=1637 cm −1 is due to the bending vibration of trapped water molecules. The broad band around

\overset{ν}{true}

\overset{ν}{true}

=1065, 962, 871, and 784 cm −1 which can be assigned to stretching vibrations ν as (P−O d ), ν as (Mo−O t ), ν as (Mo‐O b ‐Mo), and ν as (Mo‐O c ‐Mo), respectively.…”

Section: Resultssupporting

confidence: 91%

Catalyst Development for the Synthesis of Ozonides and Tetraoxanes Under Heterogeneous Conditions: Disclosure of an Unprecedented Class of Fungicides for Agricultural Application

Yaremenko

Radulov

Belyakova

et al. 2020

Chemistry A European J

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“…[30] However, after the incorporation of silica particles in the carbon framework, the graphitic nature of the carbon diminished and the peak at approximately 258 shifted to approximately 238 as a result of the formation of amorphous carbon, [38] along with some contribution in the peak from amorphous silica ( Figures 5 b to f). [39] The diffraction pattern does not show any evidence for the formation of the crystalline silica phase in the support, which is consistent with earlier reports. [26] The catalysts also showed peaks at approximately 2 q = 36.6, 42.5, and 61.78 corresponding to the (111), (2 0 0), and (2 2 0) diffraction planes of the CoO cubic phase, respectively (Figures 5 a to f).…”

Section: Characterization Of Catalystssupporting

confidence: 91%

Fischer–Tropsch Synthesis Over Cobalt Supported On Silica‐Incorporated Mesoporous Carbon

et al. 2013

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The influence of carbon–silica hybrid supports on cobalt catalysts in Fischer–Tropsch synthesishas been investigated. Mesoporous carbon–silica hybrid supports were synthesized through a hydrogen‐bonding‐assisted self‐assembly route by loading different amounts of silica (0 to 45 %) as a framework composition with mesoporous carbon. These carbon and hybrid supports were then impregnated with 15 wt. % cobalt and the resulting catalysts were characterized by various physicochemical, gravimetric, and spectroscopic methods. The dispersion of silica in the framework of mesoporous carbon modified the surface chemistry and enhanced the wetting properties of the support. Hence, the dispersion and reducibility of cobalt over the hybrid supports increased compared to those of the carbon‐supported catalyst. However, above the optimum silica incorporation of 34 %, the possibility of phase separation and structural transformation of silica at the high carbonization temperature decreased the dispersion and reducibility of the supported Co catalysts. The carbon‐supported catalyst showed a quick drop in the activity during the initial stages of the reaction due to the migration of cobalt particles over the hydrophobic and inert support surface. On the contrary, carbon–silica hybrid supports inhibited the mobility of cobalt particles and produced a higher density of active Co0 sites, leading to a higher initial activity. Carbon–silica‐supported catalysts with a silica content of up to 34 % were found to exhibit excellent steady state Fischer–Tropsch synthesis activity and C5+ selectivity compared to only carbon and carbon–silica‐supported catalyst with >34 % silica incorporation.

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“…For samples S3 and S4, the signal located at 260 nm is related to the presence of the aromatic ring existing in the AMP structure. Finally, the molybdenum catalyst (sample S4) shows three additional signals (as compared to sample S3) located at 220, 310 and 700 nm, which can be attributed to Mo-O bonding of isolated molybdenum species in pseudo-octahedral coordination [23], octahedral molybdenum sites of dense phase MoO3 [12] and electronic transition between Mo(V) and Mo(VI) species [24], respectively. Low intensity of the signal positioned at 700 nm involves low amount of Mo(V) species in the synthesized catalyst.…”

Section: Characterization Of Functionalized Sba-15 Materials and Mo(vmentioning

confidence: 95%

Mo(VI) Complexes Immobilized on SBA-15 as an Efficient Catalyst for 1-Octene Epoxidation

2017

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SBA-15 materials were functionalized through a post-synthetic methodology with molybdenum-Schiff bases to provide catalytic activity in epoxidation reactions. Thus, glycidoxypropyl functionalities were first attached to the surface of the mesostructured silica, followed by the reaction of the immobilized oxirane groups with 2-amino propyl pyridine. This reaction allowed the obtaining of (hydroxypropyl)-2-aminomethyl pyridine ligands, directly tethered to the surface of the mesoporous silica-based SBA-15, which resulted in excellent chelating ligands to immobilize dioxo molydenum species by a reaction with MoO 2 (acac) 2. This investigation comprises a thorough characterization of the process for building the immobilized molybdenum-Schiff base complexes, as well as the use of the obtained materials in 1-octene oxidation in the presence of organic hydroperoxides. These materials displayed high intrinsic catalytic activity in the epoxidation of 1-octene with organic hydroperoxides under a wide variety of conditions, although both the reaction solvent as well as the nature of the organic hydroperoxide, exerted a dramatic influence on the catalytic activity of these heterogeneous oxidation catalysts. Thus, whereas nonpolar solvents provided good epoxide yields with high efficiency in the use of the oxidant, polar solvents depressed the catalytic activity of the supported Mo-Schiff bases. These results have been ascribed to the competition with the solvent, when polar, for binding to the metal sites, thus avoiding the formation of the hydroperoxo-metal cycle and the epoxidation of the olefin. The catalysts presented here show good reusability with low catalytic activity decay after the first reuse.

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Silica supported amorphous molybdenum catalysts prepared via sol–gel method and its catalytic activity

Cited by 43 publications

References 31 publications

Catalyst Development for the Synthesis of Ozonides and Tetraoxanes Under Heterogeneous Conditions: Disclosure of an Unprecedented Class of Fungicides for Agricultural Application

Catalyst Development for the Synthesis of Ozonides and Tetraoxanes Under Heterogeneous Conditions: Disclosure of an Unprecedented Class of Fungicides for Agricultural Application

Fischer–Tropsch Synthesis Over Cobalt Supported On Silica‐Incorporated Mesoporous Carbon

Mo(VI) Complexes Immobilized on SBA-15 as an Efficient Catalyst for 1-Octene Epoxidation

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