Synthesis of Fe‐MCM‐41 from silatrane and FeCl₃ via sol–gel process and its epoxidation acivity

Abstract

An iron-containing mesoporous molecular sieve, or Fe-MCM-41, was successfully synthesized the via sol-gel technique using silatrane and FeCl 3 as the silicon and iron sources, and was characterized using various techniques. Many factors were investigated, namely, reaction temperature and time, calcination rate, and iron amount in the reaction mixture. It was found that the optimum conditions in which to synthesize Fe-MCM-41 was to carry out the reaction at 60• C for 7 h using a 1 • C min −1 calcination rate and a 550• C calcination temperature. The catalytic activity and selectivity of styrene epoxidation using hydrogen peroxide showed that the selectivity of the styrene oxide reached 65% at a styrene conversion of 22% over the 1%wt catalyst.

Highly Loaded Fe-MCM-41 Materials: Synthesis and Reducibility Studies

“…The as-synthesized material [Figure 3 (a)] shows the existence of at least three signals corresponding to different environments, characterized by different values of the Lande g -factor. The dominant iron environments are represented by ESR signals at g = 4.3 and g = 2.0, which are respectively assigned to Fe 3+ in tetrahedral framework sites and in octahedral (cation exchange or interstitial) sites [38,39]. Similar observations have also been reported on other iron-containing MCM-41 materials [32,40].…”

Enhanced adsorption of acetylsalicylic acid over hydrothermally synthesized iron oxide-mesoporous silica MCM-41 composites

“…As shown in Fig. 1 B ( For samples prepared by the hydrothermal synthesis, one absorption band at 274 nm was detected for isolated octahedral Fe(III) species, which absorption band can be assigned to the charge transfer band from the non-bonding orbital of O 2 − to the t 2g and e g orbital of Fe(III) [27,28] . The intensity increased significantly with the increase of the Fe/Si molar percentage from 5 to 25 mol%, however, it remained constant or decreased after 35 mol%.…”

“…3 B, the intensity of the absorption bands of the composites prepared by the impregnation method also increased with the increase of Fe/Si ratio from 5 to 35 mol%. There were two charge transfer bands detected for tetrahedral and octahedral co- orbitals of Fe(III) [27,28] . The isolated tetrahedral Fe(III) ion was observed in the samples prepared by the impregnation method, probably due to more Fe(III) ion from the iron precursor can directly incorporate inside the pore of the MCM-41 [32] when the composites were prepared by the impregnation method.…”

A Comparative Characterization of the HPA‐MCM‐48 Type Catalysts Produced by the Direct Hydrothermal and Room Temperature Synthesis Methods

“…The sample was heated from ambient temperature to 823 K with a heating rate of 1 • C/min and kept at this temperature for 6 more hours under constant flow of dry air. It is known that the crystallinity of the product increases as the heating rate (calcination rate) decreases or the calcination duration increases [24]. Hence a low heating rate (1 • C/min) was employed and a long total calcination time of 15 hours was achieved.…”