Improved Cyclohexane Oxidation Catalyzed by a Heterogenized Iron (II) Complex on Hierarchical Y Zeolite through Surfactant Mediated Technology

Abstract

The hydrotris (pyrazol-1-yl) methane iron (II) complex [FeCl 2 (Tpm)] [Tpm = HC(C 3 N 2 H 3 ) 3 ] was successfully immobilized, by the incipient wetness impregnation method, in parent and hierarchical Y zeolite modified through surfactant mediated methodology using different bases (NH 4 OH, NaOH or TPAOH). The catalytic performance and recyclability of supported Fe complex was evaluated in the oxidation of cyclohexane with hydrogen peroxide to cyclohexanol and cyclohexanone under mild conditions and two distinct behaviors were observed: using commercial Y and modified Y with NaOH the complex is anchored mainly at the outer surface of the zeolite supports, resulting in high lixiviation after the first catalytic cycle. When NH 4 OH and TPAOH are used during the zeolite treatments the particular textural parameters exhibited by these two supports are able to effectively retain the complex molecules, resulting in a high recyclability observed after three consecutive cycles, especially when NH 4 OH treated zeolite was used as support.[a] V.

State of the Art and Perspectives of Hierarchical Zeolites: Practical Overview of Synthesis Methods and Use in Catalysis

“…The effect of different bases was seen in terms of the Fe-complex immobilization characteristics, which could possibly show important consequences on the catalytic behavior and recycling. [302] Like in previous work from Van-Dúnem et al, where different bases were tested, different mesoporogens can also influence the outcome of hierachical Y zeolites. [302] Van-Dúnem et al and Al-Ani et al both used CTAB to assist in their desilication approach.…”

“…[302] Like in previous work from Van-Dúnem et al, where different bases were tested, different mesoporogens can also influence the outcome of hierachical Y zeolites. [302] Van-Dúnem et al and Al-Ani et al both used CTAB to assist in their desilication approach. [302][303][304] Al-Ani et al suggested that 12-MR zeolites (FAU, *BEA, MOR, LTL), which are accessible by the surfactant, facilitate the formation of regular mesopores during the desilication.…”

Sustainability in Catalytic Cyclohexane Oxidation: The Contribution of Porous Support Materials

“…Later, in 2018, Van-Dúnem et al accomplished the immobilization of the complex [FeCl 2 (Tpm)] in the parent and hierarchical zeolite Y [61]. The authors used the incipient wetness impregnation method and also a modification treatment through a surfactant intermediated methodology using various bases (NH 4 OH, NaOH, or TPAOH).…”

“…Table 4. Textural parameters for the studied materials [61]. The catalytic performance and recyclability of the immobilized Fe complex was evaluated towards the oxidation of cyclohexane with hydrogen peroxide.…”

“…Effects of the recycling of FeCl2Tpm@Y_B on the products' yield of cyclohexane oxidation. Reproduced with permission of[61], copyright 2018 Wiley-VCH.…”