Synthesis of FeCoMnAPO-5 Molecular Sieve and Catalytic Activity in Cyclohexane Oxidation by Oxygen
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Catalysis Letters Vol. 99, Nos. 3–4, February 2005 (Ó 2005) DOI: 10.1007/s10562-005-2128-2
Synthesis of FeCoMnAPO-5 molecular sieve and catalytic activity in cyclohexane oxidation by oxygen Lipeng Zhou, Jie Xu*, Hong Miao, Xiaoqiang Li, and Feng Wang State Key Laboratory of Catalysis, Dalian Institute of Chemical Physics, Graduate School of the Chinese Academy of Sciences, Chinese Academy of Sciences, 457 Zhongshan Road, Dalian 116023, P.R. China
Received 21 July 2004; acccepted 1 October 2004
A new FeCoMnAPO-5 with AFI structure was synthesized under hydrothermal conditions and characterized by XRD, FT-IR, X-ray fluorescence, nitrogen adsorption and SEM. The oxidation of cyclohexane with molecular oxygen was studied over the catalyst at 403 K. It show d higher activity compared to FeAPO-5, CoAPO-5 and MnAPO-5. The FeCoMnAPO-5 catalyst was recycled twice without loss of activity or selectivity. KEY WORDS: molecular sieves; aluminophosphate; oxidation; cyclohexane.
1. Introduction
2. Experimental
Since 1986 when metal incorporated aluminophosphate molecular sieves were first reported, numerous metals, which include Ti, V, Cr, Mn, Co, Ni, Zn, Fe, Mg, etc., have been introduced into their framework in order to enhance their acid and redox properties [1–3]. FeAPO-5, CoAPO-5 and MnAPO-5 molecular sieves have been widely studied in many kinds of reactions and show remarkable catalytic performance. For example, they have been used as catalysts for the catalytic oxidation:of cyclohexane to cyclohexanol and cyclohexanone [4]; of p-xylene to terephthalic acid; and of p-cresol to p-hydroxyl-benzaldehyde in mathanolic sodium hydroxide [5]. Also, the activity of these materials has been found for the ammoximation of cyclohexanone with ammonia and H2 O2 to e-caprolactam [6]. To our knowledge, there is no report on simultaneously substituted the three metals (Fe, Co, Mn) into its framework and of the resulting catalytic behavior, although the substitution of a single metal into aluminophosphate molecular sieves is well recognized [1,7]. For the potential wide applications, it is interesting and necessary to study the preparation method of FeCoMnAPO-5 and its catalytic properties. This paper constitutes the first report of the synthesis, characterization and catalytic performance in cyclohexane oxidation of FeCoMnAPO-5, where there is incorporated of three metals into the AIPO-5 framework. It is found to be an active, recyclable heterogeneous catalyst for the partial oxidation of cyclohexane by molecular oxygen under mild conditions.
2.1. Sample preparation and characterization
*To whom correspondence should be addressed: E-mail: [email protected].
Pseudoboehmite (78.6 wt% Al2 O3 ), H3 PO4 (85 wt% sol in water), Co(CH3 COO)2 4H2 O, Mn(CH3 COO)2 4H2 O and Fe(NO3 )3 9H2 O were used as the sources of aluminium, phosphorus, cobalt, manganese and iron. FeCoMnAPO-5 was synthesized from the gel with following molar composition:0.02 Fe:0.02 Co:0.02 Mn:0.94 Al:1.0 P:0.75 Et3 N:20 H2 O. In a typical synthesis, the calculated amou
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