Surface Cobalt Silicate and CoOx Cluster Anchored to SBA-15: Highly Efficient for Cyclohexane Partial Oxidation

Abstract

The present investigation showed that the surface cobalt silicate and CoO x cluster anchored to SBA-15 are highly efficient heterogeneous catalysts for the cyclohexane partial oxidation with air-like O 2 (20%)-N 2 (80%) mixture as oxidant in the continuously stirred tank reactor at 413 K and 1.0 MPa. Typically, selectivity of 84.6% at cyclohexane conversion of 14.5% can be achieved in a period of 2 h reaction. The performance of Co-catalyst is affected by the nature of Co species introduced to SBA-15. The surface cobalt silicate with higher proportion of ''isolated'' Co 2? sites shows better result than the well dispersed CoO x clusters mainly on the internal surface of SBA-15. Furthermore, different preparation method also influences the porosity of SBA-15 and accessibility to Co sites, which may in turn affect on the reaction performance.

Shape, Morphology, and Phase Transitions during Co Oxide Growth on Au(111)

“…Recently, interest has emerged in the catalytic properties of cobalt and cobalt-containing oxides. − Cobalt oxides have shown activity for a wide range of reactions, including oxygen reduction in fuel cells and solar cells, , NO reduction, methane combustion, partial oxidation of hydrocarbons, low temperature, selective CO oxidation, ethanol steam reforming, and the water gas shift reaction . Many of these reactions typically require precious metals, making Co oxides attractive even if they may not be the optimal catalyst.…”

One-Pot Synthesis and Characterization of Cu-SBA-16 Mesoporous Molecular Sieves as an Excellent Catalyst for Phenol Hydroxylation

“…Many efforts have been devoted to synthesis of metal loaded mesoporous molecular sieves by direct synthesis and impregnation methods [3][4][5]. However, it is very difficult to introduce metal ions into SBA-16 by direct hydrothermal synthesis due to the difficulty in the formation of metal-O-Si bonds under the strong acidic conditions [6].…”

“…The problem may be that a different pH range was expected for the formation of ordered structure (pH ( 1) and for the introduction of metal species (pH [ 1) in one-pot hydrothermal synthesis [2]. Evaporation induced self-assembly (EISA) strategy has been successfully applied to the synthesis of ordered mesoporous silica materials (SBA-15, SBA-16) and various mesoporous metal oxides (TiO 2 , ZrO 2 , Al 2 O 3 , WO 3 and SnO 2 ) utilizing triblock copolymer as the template [9][10][11][12].…”

Cobalt molybdenum oxide catalysts for selective oxidation of cyclohexane

“…Overall selectivity to KA oil was 95% in a solvent free environment at 160°C and 1.0 MPa O 2 pressure in 6 h . Li et al also reported on Co/SBA‐15 where cobalt silicate was seen on the surface and cobalt oxide was anchored in the pores of SBA‐15. Collective effect of cobalt forms resulted in 14% conversion with 85% selectivity.…”