Cobalt(II) acetylacetonate complex immobilized on aminosilane‐modified SBA‐15 as an efficient catalyst for epoxidation of trans‐stilbene with molecular oxygen

Abstract

From environmental and economic points of view, it is highly desirable to develop a clean and efficient catalytic process to produce epoxides. An attractive approach is to use a solid, recyclable catalyst and molecular oxygen as the oxidant without any sacrificial reductant or other additives. Nonetheless, the catalysts reported up to now still cannot balance catalytic activity with epoxide selectivity. It is of great importance to explore novel catalysts with both high activity and selectivity for the epoxidation of olefins. In this work, cobalt(II) acetylacetonate (Co(acac)2) was covalently bonded to the silica surface of SBA‐15 molecular sieve by multi‐step grafting using 3‐aminopropytrimethoxysilane (APTS) as coupling agent. Characterizations with nitrogen physisorption, X‐ray diffraction, transmission electron microscopy, Fourier transform infrared spectroscopy and thermogravimetric analysis suggested that the metal complex was successfully immobilized on the aminosilane‐modified SBA‐15 surface and the channel structure remained intact. The synthesized Co(acac)2APTS@SBA‐15 catalyst was used in the epoxidation of trans‐stilbene (TS) with molecular oxygen. Compared to the sample prepared by the impregnation method as well as Co(acac)2 solutions under the same reaction conditions, the Co(acac)2 immobilized catalyst exhibited remarkably higher TS conversion and trans‐stilbene oxide (TSO) selectivity. An increase in TS conversion with Co content was observed when the Co loading was lower than 0.70% and the 0.70Co(acac)2APTS@SBA‐15 sample exhibited the best catalytic performance. Up to 50.1% of TS conversion could be achieved within 6 h, affording TSO selectivity as high as 96.7%. The superior catalytic performance of this particular catalyst is attributed to the high activity of the immobilized Co(acac)2 species on SBA‐15. Copyright © 2016 John Wiley & Sons, Ltd.

Excellent alkene epoxidation catalytic activity of macrocyclic‐based complex of dioxo‐Mo(VI) on supermagnetic separable nanocatalyst

“…[15][16][17][18] A main idea for supporting of metal complexes is to anchor the metal complexes onto large-surface-area inorganic materials such as zeolites and metal oxides. [16,[19][20][21][22][23][24][25] Nowadays, magnetite nanoparticles are of particular interest because of their unique properties including high surface area, low toxicity, ability to be separated and biocompatibility. [16,[26][27][28][29][30] Magnetic separation renders the recycling of catalysts from solution using external magnetic fields much easier than filtration and centrifugation.…”

Epoxidation of cyclohexene with H2O2 over efficient water‐tolerant heterogeneous catalysts composed of mono‐substituted phosphotungstic acid on co‐functionalized SBA‐15

“…The small‐angle XRD patterns of silylated SBA‐15 and hybrid catalysts were exhibited in Figure (c). Silylated SBA‐15 displayed an intense peak that corresponded to (100) reflection, and two relative weak peaks attributed to (110) and (200) reflections, which were indexed to highly ordered hexagonal lattice as reported . Immobilization of heteropolyanions on mesochannels of silylated SBA‐15 resulted in slightly reduced intensities of these three reflection peaks with slight shifts to higher 2 θ values compared with silylated SBA‐15.…”

Developing Eco-Friendly and Cost-Effective Porous Adsorbent for Carbon Dioxide Capture

“…Some of the most remarkable strategies are CO 2 capturing and conversion technologies, such as chemical, photocatalytic [ 4 , 5 ], and electrocatalytic reduction [ 6 , 7 , 8 ], for which the first step is efficient CO 2 capture. In many of these technologies, heterogenous conversion catalysts, function [ 9 , 10 , 11 ], in the first step as, solid adsorbents and some of these entail materials such as silica [ 12 , 13 , 14 ], metal-organic frame (MOFs) [ 3 ], and carbon-based materials [ 14 , 15 , 16 , 17 ]. Some commonly researched carbon-based adsorbent materials entail activated carbon [ 18 ], ordered mesoporous polymer/carbon (OMP/OMC) [ 14 , 19 , 20 ], activated carbon fibers [ 21 , 22 ], graphene [ 2 , 17 ], and graphene oxide [ 23 , 24 , 25 ].…”