Simple and Green Adipic Acid Synthesis from Cyclohexanone And/Or Cyclohexanol Oxidation with Efficient (NH4)Xhymzpmo12o40 (M: Fe, Co, Ni) Catalysts
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Available online at BCREC Website: https://bcrec.undip.ac.id Bulletin of Chemical Reaction Engineering & Catalysis, 13 (2) 2018, 386-391 Research Article Simple and Green Adipic Acid Synthesis from Cyclohexanone and/or Cyclohexanol Oxidation with Efficient (NH4)xHyMzPMo12O40 (M: Fe, Co, Ni) Catalysts Sihem Mouanni1, Tassadit Mazari1,2*, Sihem Benadji1, Leila Dermeche1,2, Catherine Marchal-Roch3, Cherifa Rabia1 1Laboratoire de Chimie du Gaz Naturel, Faculté de Chimie, Université des Sciences et de la Technologie Houari Boumediene (USTHB), BP 32, El-Alia, 16111 Bab-Ezzouar, Alger, Algeria 2Département de Chimie, Faculté des Sciences, Université Mouloud Mammeri (UMMTO), 15000 Tizi Ouzou, Algeria 3ILV-UMR 8180 CNRS, Université de Versailles -St Quent -en-Yvelines, Bâtiment Lavoisier, 45 avenue des Etats-Unis, 78035 Versailles Cedex, France Received: 12nd November 2017; Revised: 18th February 2018; Accepted: 19th February 2018; Available online: 11st June 2018; Published regularly: 1st August 2018 Abstract The oxidation of cyclohexanone and/or cyclohexanol to adipic acid (AA) was performed at 90 °C with a reaction time of 20 h, in the presence of H2O2 as oxidant and transition metal substituted ammonia polyoxometalates of formula, (NH4)xHyMzPMo12O40 (M: Fe, Co, or Ni, and x = 2.5 or 2.28) as catalysts. The catalytic results showed that the AA yield is sensitive to the transition metal nature and to the reaction conditions (sample weight and substrate amount). The (NH4)2.29H0.39Co0.16PMo12O40 was found to be the better catalytic system toward AA synthesis from cyclohexanone oxidation, with 40% of AA yield Copyright © 2018 BCREC Group. All rights reserved Keywords: Keggin mixed salts; Oxidation; Hydrogen peroxide; Cyclohexanone; cyclohexanol; Adipic acid How to Cite: Mouanni, S., Mazari, T., Benadji, S., Dermeche, L., Marchal-Roch, C., Rabia, C. (2018). Simple and Green Adipic Acid Synthesis from Cyclohexanone and/or Cyclohexanol Oxidation with Effi- cient (NH4)xHyMzPMo12O40 (M: Fe, Co, Ni) Catalysts. Bulletin of Chemical Reaction Engineering & Ca- talysis, 13 (2): 386-392 (doi:10.9767/bcrec.13.2.1749.386-392) Permalink/DOI: https://doi.org/10.9767/bcrec.13.2.1749.386-392 1. Introduction lar oxygen [2,3], or hydrogen peroxide [4-6] that can reduce the use of toxic and hazardous subs- The worldwide demand for clean chemical tances is the sought aim. It was noted that with processes for adipic acid synthesis has ex- these oxidants, the active oxygen species con- panded greatly in recent decades. So, the devel- tent is high with 100% for molecular oxygen and opment of catalytic oxidation systems with envi- 47% for hydrogen peroxide. Hydrogen peroxide ronmentally benign oxidants as air [1], molecu- is the oxidant that has received much attention because it is safer in storage and operation, with water as the sole by product. * Corresponding Author. E-mail: [email protected] / Adipic acid (AA) is of a great interest, in the [email protected] (T. Mazari) manufacture of nylon-6,6 polyamide [7]. Its in- bcrec_1749_2017 Copyright © 2018, BCREC, ISSN 1978-2993 Bulletin of Chemical Reaction Engineering & Catalysis, 13 (2), 2018, 387 dustrial production takes place on two steps, method described by Mizuno et al. [23]. It con- cyclohexane oxidation to a mixture of cyclohex- sists to adding, in stoichiometric ratios, an anol and cyclohexanone (noted KA oil) in pres- aqueous solution of M(NO3)2 (0.16 M) with Mn+: ence of air (first step) then the KA oil is oxi- Co2+ or Ni2+ or Fe(NO3)3 (0.24 M) to aqueous so- dized to AA by nitric acid (second step). The ni- lution of H3PMo12O40 (0.06 M) followed by a so- tric acid used is the source of NOx emission lution of NH4Cl (0.08 M). The precipitate was whose most harmful is the N2O [8-10]. dried at 50 °C under vacuum with a rotary eva- Polyoxometalates (POMs), large family of porator and recovered. anionic metal-oxygen clusters, having chemical properties such as strong oxidative powers and 2.2 Polyoxometalates Characterization strong Brönsted and Lewis acidities have espe- POMs elemental analysis was performed on cially received much attention in the area of an atomic emission spectrometer (AES) type the oxidation catalysis [11-14]. The POMs Perkin Elmer, Optima 2000 D.VS. Porosity based on molybdenum, particularly, can act as measurements were carried out with liquid N2 effective catalysts for the H2O2- and O2-based on a Micromeritics ASAP 2010 instrument. IR green oxidations [15-17]. Furthermore, they are analysis was performed on a Nicolet 550 Fou- oxidatively stable and can undergo stepwise rier transform spectrometer. UV-Vis spectra multi electron redox process without any struc- were recorded on a UV-Vis Near IR spectrome- tural modification. With transition-metal- ter, of model Perkin Elmer, Lambda 19. The X- substituted POMs, it was reported that their ray diffractograms were carried out on a Sie- remarkable catalytic activities were due to the mens D-5000 diffractometer. multifunctional character of multimetallic ac- tive sites as simultaneous activation of oxi- 2.3 Catalytic test dants and substrates, reaction intermediates stabilization, oxygen-transfer and multielec- The adopted experimental method is based tron transfer [15-17]. In previous studies, we on that described in the literature [6]. An have underlined the efficiency of transition- amount of substrate (cyclohexanone or/and metal-substituted POMs [18-21] as catalysts in cyclohexanol) and a given mass of catalyst the clean oxidation of cyclohexanone and mix- were introduced into a necked flask fitted with ture of cyclohexanone/cyclohexanol to adipic a condenser and placed in an oil bath heated at acid in the presence of hydrogen peroxide with- 90 °C. The mixture (substrate and catalyst) out solvent, phase-transfer agents and adding stirred at 800 rpm, of light yellow or green, acid. color of oxidized POM (POMox), was turned In this study, a series of substituted POMs blue, color of reduced POM (POMred). The of formula, (NH4)xMzHyPMo12O40 (M: Fe, Co, or H2O2 (~ 30%) was then added in portions of 1 Ni, and x = 2.5 or 2.28) were synthesized and mL under stirring until the mixture returns its characterized by elementary analysis, Fourier initial color (yellow or green) that corresponds Transform Infrared (FT-IR) and UV-Visible to the catalyst reoxidation (POMox). POMox spectroscopies, Nitrogen physisorption and X- oxidizes a second time the substrate and the ray Diffraction (XRD) analysis. Their catalytic cycle was repeated until the disappearance of activity was examined through cyclohexanone the solution bluing (total consumption of the and/or cyclohexanol oxidation to AA with 30% reagent). The reaction time is ~ 20 h for all re- of H2O2 in free solvent conditions. The effects of actions. The reaction mixture was then placed the POM composition and the reaction condi- in cold (4 °C) for ~ 4 days. Adipic acid, one of tions were examined. the reaction products was recuperated in the form of white crystals, washed with saturated 2. Materials and Methods AA solution and dried. 2.1 Heteropolysalts preparation 3. Results and Discussion H3PMo12O40.nH2O acid was prepared by the 3.1 Heteropolysalt characterization conventional method of Tsigdinos [22]. The am- monium salt, (NH4)3PMo12O40 was prepared Elemental analysis of the salts was per- from a mixture of 2.4 mmol of H3PMo12O40 acid formed after heat treatment at 300 °C under and 3.6 mmol of urea, previously ground finely. air for 24 h to remove residual nitrates. Table 1 The powder undergoes heat treatment for 18 h shows analysis results. The stoichiometric coef- under N2 flow (7 mL/min) [20]. Mixed ammo- ficients were calculated on the basis of 12 Mo nium salts (NH4)xHyMzPMo12O40 (noted atoms per Keggin unit. The atoms numbers of MPMo12) were prepared according to the phosphorus (1 per Keggin unit), transition Copyright © 2018, BCREC, ISSN 1978-2993 Bulletin of Chemical Reaction Engineering & Catalysis, 13 (2), 2018, 388 metal and nitrogen per mole of salt, deduced IR spectra (Figure 1) of MPMo12 salts have from the analysis are in agreement with those the characteristic vibration bands of the Keg- introduced experimentally. Exception for FeP- gin anion in the 1100-300 cm-1 spectral range Mo12 salt, where the number of analyzed nitro- [24], corresponding to nas(P–Oa), nas(Mo=Od), gen atom (1.64) is lower than corresponding nas(Mo–Ob–Mo) and nas(Mo–Oc–Mo) located at theoretical value (2.28). This difference can be 1060-1064, 960-965; 866-880 and 776-799 cm-1, explained by the loss of NH4+ ions during the respectively. In addition, another vibration heat treatment prior to analysis. band associated to ammonium ions was ob- Table 2 shows that the different structural served around 1400 cm-1. All spectra of parameters depend on the nature of the metal MPMo12 are similar to that of (NH4)3PMo12O40 element in the polyoxometalate. Thus, the spe- (spectrum not shown) suggesting the conserva- cific and the micropore surfaces and the pore tion of [PMo12O40]3-, Keggin unit. and the micropores volumes of CoPMo12 salt In UV-Visible spectroscopy, a broad absorp- are largely superior to those of NiPMo12 and tion band of oxygen–molybdenum(VI) charge FePMo12 salts. The observed difference in the transfer was observed in the 250-500 nm re- structural parameters between CoPMo12 and gion for all MPMo12 salts (Figure 2) [25]. In ad- the two others salts can be related to the exis- dition to this band, another of lower intensity tence of both Co(II) and Co(III) based ammonia was observed in the 620-720 nm region in the salts as seen in UV analysis. FePMo12 has the presence of CoPMo12 salt, attributed either to highest average pore diameter. Nitrogen ad- the d-d transition of d1 Mo(V) species in octahe- sorption-desorption isotherms of different salts dral coordination and/or to d6 Co(III) species (figures not shown) are of Type II and their also in octahedral coordination, suggesting that hysteresis of Type B showing that salts are the CoPMo12 salt is partially reduced.