Methyl Group Modified MCM-41 Supported Schiff-Base Cobalt Complex and Its Catalytic Performance in Cyclohexane Oxidation

Abstract

The mesoporous molecular sieve MCM-41 was amino-functionalized using c-aminopropyltriethoxysilane. The obtained NH 2 -MCM-41 was then hydrophobic modified by methyltriethoxysilane, dimethyldiethoxysilane and trimethylethoxysilane, respectively. N,N 0 -Bis (salicylidene) ethylenediiminocobalt (Cosalen) was grafting into the modified MCM-41 through the complex effect of NH 2 group. The prepared Cosalen/(CH 3 ) n -NH 2 -MCM-41 (n = 0, 1, 2, 3) were characterized by the technique of FT-IR, XRD, N 2 adsorption-desorption, TG and so on. The catalytic performance of the Cosalen/(CH 3 ) n -NH 2 -MCM-41 (n = 0, 1, 2, 3) for the cyclohexane liquid-phase oxidation by oxygen were compared. The results showed the selectivity of the polar product cyclohexanol and cyclohexanone significantly improved with the introduction of methyl groups into the surface of the MCM-41 carrier. Using Cosalen/CH 3 -NH 2 -MCM-41 as catalyst, the conversion of cyclohexane is 8.3 % under mild conditions with oxygen in absence of solvent, only 0.1 % cyclohexyl hydroperoxide was among the products, the total selectivity of the cyclohexanone and cyclohexanol is up to 93.6 %. Graphical Abstract Methyltriethoxysilane, dimethyldiethoxysilane and trimethylethoxysilane were used to modify the hydrophobic performance of the mesoporous molecular sieve MCM-41, the active component Cosalen was immobilized on the carrier through NH 2 group after amino-functionalized using c-aminopropyltriethoxysilane. In the solvent-free cyclohexane oxidation with molecular oxygen, the obtained Cosalen/CH 3 -NH 2 -MCM-41 as catalyst, the conversion of cyclohexane is 8.3 %, only 0.1 % cyclohexyl hydroperoxide was among the products, the total selectivity of the cyclohexanone and cyclohexanol is up to 93.6 %.

Ionic Liquid-Modified Co/ZSM-5 Catalyzed the Aerobic Oxidation of Cyclohexane: Toward Improving the Activity and Selectivity

“…Therefore, developing new highly efficient and robust heterogeneous catalysts for industrial-scale selective aerobic oxidation of cyclohexane is of great importance. In the last several years, various heterogeneous catalysts have been widely exploited for cyclohexane catalytic aerobic oxidation. − For example, supported metalloporphyrins, − transition metals with Schiff base ligands, , cobalt compounds, − copper complexes, − and metal nanoparticles − have been developed to promote the cyclohexane conversion and the selectivity of KA oil under relatively mild and environmentally friendly reaction conditions. However, most of these catalyst systems either required high temperature/pressure or suffered from poor selectivity to KA oil.…”

MCM‐41 Immobilized Acidic Functional Ionic Liquid and Chromium(III) Complexes Catalyzed Conversion of Hexose into 5‐Hydroxymethylfurfural

“…Most likely some pores were blocked by the aminopropyl and acid ionic liquid. [41] But the average pore diameters decreased in the samples, which suggested that acid ionic liquids and the Cr-salphen/ salten complexes may be well confined in the pores of mesoporous silica.…”

“…In the XRD pattern ( Figure 3) of pure MCM-41, a very strong reflection at 2θ＝1.89° for d100 and also two other weaker reflections at 2θ＝3.79° and 4.35° for d110 and d200, respectively, can be indexed to well-ordered mesoporous material of a hexagonal symmetry. [41] After immobilization of Cr complex, the intensity of the peak at (100) decreased largely, the higher angle peaks in the parent sample no longer appeared. It is mainly due to a loss of the mesoporous order.…”

Study on the relationship of catalytic activities and o‐Ps annihilation properties of supported palladium species chelated by different functional groups

“…After completion, the amino group functionalized MCM‐41 (M41@N) was separated by centrifugation, washed with ethanol, and dried at 333 K for 8.0 h under reduced pressure (Scheme 1a). [ 23–25 ]…”

“…After completion, the amino group functionalized MCM-41 (M41@N) was separated by centrifugation, washed with ethanol, and dried at 333 K for 8.0 h under reduced pressure (Scheme 1a). [23][24][25] The substituted benzaldehydes (12.0 mmol) and M41@N (1.0 g) were added to a bottle containing 40-mL ethanol. The mixture was magnetically stirred at 358 K for 24 h under the atmosphere.…”