Continuous Treatment of Phenol over an Fe2O3/γ-Al2O3 Catalyst in a Fixed-Bed Reactor

Abstract

Fe 2 O 3 /γ-Al 2 O 3 catalysts were prepared using the wet impregnation method and characterized by Xray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and nitrogen adsorption-desorption. The continuous catalytic wet hydrogen peroxide oxidation of an aqueous phenol solution over Fe 2 O 3 /γ-Al 2 O 3 was studied in a fixedbed reactor. The effects of several factors, such as the weight hourly space velocity (WHSV), particle size, reaction temperature, H 2 O 2 concentration, and initial pH, were studied to optimize the operation conditions for phenol mineralization. For a 1 g L −1 phenolic aqueous solution, the phenol was nearly completely removed and chemical oxygen demand (COD) removal was approximately 92 % at steady-state conditions with a WHSV of 2.4×10 −2 g PhOH h −1 g cat −1 at 80°C with 5.1 g L −1 H 2 O 2 . The long-term stability of the Fe 2 O 3 / γ-Al 2 O 3 catalyst was also investigated for the continuous treatment of phenolic water. The removal of phenol and COD exhibited a slowly decreasing trend, which was primarily due to the complexation of active sites with acid organic compounds and the adsorption of intermediate products. The deposition of organic carbon and Fe leached from the catalyst had a small role in the partial deactivation of the catalyst. The Fe leached from the catalyst partially contributed to the phenol removal during a short run. However, this contribution could be neglected after 36 h because the Fe leached from the catalyst decreased to approximately 5 mg L −1 .

Enhanced Stability of Abundant Amorphous Iron (III) oxide Grafted AlSBA‐15 as Highly Efficient Heterogeneous Fenton Catalyst for the Destruction of Phenol

“…To explore the location of grafted iron oxide over the support, whether iron is bonded with remaining silanols or alumina cluster in the mesoporous support, synthesized catalysts have been further characterized using 27 Al MAS NMR, XPS, TPR, and HR-TEM techniques. 27 Al MAS NMR is a suitable technique to reliably identify the presence of iron in the close vicinity of aluminium through the paramagnetic broadening of NMR signal. The aluminium nuclei peak get broadened if it is bonded and/or in the close vicinity of paramagnetic species like iron.…”

“…[17] This unique quality of alumina encouraged the researchers to engage iron oxide supported alumina catalysts for the degradation of phenol up to 5000 ppm. [18][19][20][21][22][23][24][25][26][27][28][29][30] Notably, Bautista et al studied the performance of Fe 2 O 3 /Al 2 O 3 powdered catalyst (4%Fe) in the CWPO of phenol up to 1500 ppm. However, the leached iron content in the water increased up to 10% with an increase in the initial phenol concentration, and a decrease in the mineralization levels (42%) was observed.…”

“…Herein, using SED technique, we grafted highly dispersed 24 wt% of iron over SBA-15, and 10 wt% alumina coated SBA-15 (AlSBA-15). The synthesized catalysts have been meticulously characterized using low and wide-angle XRD, N 2 adsorption-desorption studies, SEM-EDS, HR-TEM, XPS, 27 Al MAS NMR, and H 2 -TPR techniques to understand the state of grafted iron oxide and kind of interaction exist between the alumina support and grafted iron oxide species. The synthesized catalysts have been employed as heterogeneous Fenton catalyst towards the degradation of phenol in a batch reactor.…”

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24 wt% of iron has been successfully grafted as amorphous iron oxide over mesoporous channels of SBA-15 and 10 wt% alumina coated SBA-15 (AlSBA-15) using selective extraction deposition (SED) technique. The synthesized materials have been characterized using XRD, N 2 adsorption studies, SEM-EDS, 27 Al MAS NMR, XPS, H 2 -TPR, and HR-TEM techniques. 27 Al MAS NMR and XPS characterization results revealed that iron has been preferentially grafted over alumina.

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“…The synthesized materials have been characterized using XRD, N 2 adsorption studies, SEM-EDS, 27 Al MAS NMR, XPS, H 2 -TPR, and HR-TEM techniques. 27 Al MAS NMR and XPS characterization results revealed that iron has been preferentially grafted over alumina. The increased binding energy of the Fe2p electron (XPS) in the 24wt %Fe/ AlSBA-15 confirms the existence of strong donor-acceptor interaction between grafted iron oxide and an alumina support.In TPR studies, unlike silica support, AlSBA-15 tuned the reduction property of various grafted oxidic iron species, which is evidenced by shifting of iron reduction peak to a high temperature of 436°C.…”