Metals modified Diatomite (Me-D) and Zeolite (Me-Z), prepared by impregnation method, and Metals-doped Carbon Xerogel (Me-CX), synthetized by sol-gel method followed by an ion exchange stage, were tested as catalysts in Catalytic Wet Air Oxidation (CWAO) of phenol in aqueous solution. The catalysts were characterized by SEM-EDX, TEM, FTIR and XRD methods. CWAO process was conducted in thermostated batch (Me-CX, Figure 1a) and fixed bed (Me-D and Me-Z, Figure 1b) reactors. Based on the maximum efficiency values the following series were depicted: (1) Fe-D &gt; Zn-D &gt; Cu(a)-D ≈ Ni-D &gt; D &gt; Mn-D &gt; Ce-D &gt; Cu(b)-D &gt; Co-D; (2) Cu(b)-Z &gt; Ce-Z &gt; Zn-Z &gt; Ni-Z ≈ Cu(a)-Z &gt; Co-Z &gt; Fe-Z ≈ Mn-Z &gt; Na-Z; (3) Co-CX &gt; Ce-CX &gt; Fe-CX &gt; Ni-CX &gt; Zn-CX &gt; K-CX. The influence of temperature, air flow and phenol initial concentration over the process efficiency was also studied. The optimal reaction conditions were: 1 g catalyst, 1000 mg/L phenol initial concentration, 60°C, 30 L/h air flow and 360 min, in case of Cu(b)-Z catalyst and 0.15 g catalyst, 100 mg/L phenol initial concentration, 60°C, 40 L/h air flow and 180 min, in case of Co-CX catalyst. Reaction pathway and kinetics for the CWAO of phenol were studied for the first catalyst in each series. The results disclosed a pseudo first-order process and a decreasing of catalysts’ efficiency, as kobs, Co-CX &gt;&gt; Fe-D &gt; Cu-Z. In agreement with literature data, the proposed oxidation pathway was divided, into two major directions, “Ortho (or Para)-oxidation pathway” based on the oxidation organic products effectively identified by HPLC (oxalic, formic, fumaric, and acetic acids), Figure 2.

Metals modified diatomite, zeolite and carbon xerogel as catalysts for catalytic wet air oxidation of phenol: Characterization, oxidation efficiency and reaction pathway

254th National Meeting (2017)

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