ALMA MATER STUDIORUM – Università di Bologna FACOLTÀ DI CHIMICA INDUSTRIALE Dipartimento di Chimica Industriale e dei Materiali NEW CATALYTIC PROCESSES FOR THE SYNTHESIS OF ADIPIC ACID Tesi di dottorato di ricerca in CHIMICA INDUSTRIALE (Settore CHIM/04) Presentata da Ing. Katerina Raabova Relatore Coordinatore Prof. Dr. Fabrizio Cavani Prof. Dr. Fabrizio Cavani Correlatore Dr. Stefano Alini ciclo XXIII Anno 2010 1. Introduction ......................................................................................................1 2. Adipic acid .........................................................................................................5 2.1 Physical chemical properties .....................................................................5 2.2 Application of adipic acid ...........................................................................5 2.3 Production of AA ........................................................................................6 2.4 Current industrial processes ......................................................................7 2.4.1 First step: Oxidation of cyclohexane with air .....................................7 2.4.2 Alternative ways of production of KA oil ...........................................9 2.4.3 Second step: Oxidation of KA oil with nitric acid ............................. 10 2.5 Environmental impact of the second step ............................................... 13 2.6 Methods for N2O abatement ..................................................................... 14 2.6.1 Catalytic abatement .......................................................................... 14 2.6.2 Thermal decomposition .................................................................... 16 2.6.3 Using N2O as a reactant ..................................................................... 16 3. Alternative ways for synthesis of adipic acid ................................................. 19 3.1 First step of the synthesis: oxidation of cyclohexane .............................. 19 3.1.1 Homogeneous catalysis..................................................................... 19 3.1.2 Heterogeneous catalysis ................................................................... 20 3.1.2.1 O2/air .......................................................................................................................... 20 3.1.2.2 Tert-butyl hydroperoxide .................................................... 21 3.1.2.3 Hydrogen peroxide ........................................................................................... 23 3.2 Second step of the synthesis: ketone or/and alcohol oxidation .............. 24 3.2.1 Oxygen ............................................................................................... 24 3.2.2 Hydrogen peroxide ........................................................................... 25 3.3 One step oxidation of cyclohexane ........................................................... 25 3.4 Alternative starting materials .................................................................. 27 3.4.1 Cyclohexene as a starting material ................................................... 27 3.4.1.1 Cyclohexene oxidation by oxygen .......................................................... 28 3.4.1.2 Cyclohexene oxidation by HP, TBHP .................................................... 29 3.4.1.2.1 One-step oxidation ..................................................................... 29 3.4.1.2.2 Two-Step oxidation .................................................................... 30 3.4.1.2.3 Three step oxidation of cyclohexene ................................. 31 3.4.2 Butadiene as a starting material ....................................................... 32 3.4.3 N-hexane as a starting material ........................................................ 33 3.4.4 D-glucose as a starting material ....................................................... 34 - FIRST PART – .................................................................................................... 39 Oxidation of cyclohexanone with molecular oxygen catalyzed by Keggin-type polyoxometalates 4. Polyoxometalates (POMs) ............................................................................... 40 4.1 Structure ................................................................................................... 41 4.2 Salts of HPA ............................................................................................... 46 4.3 Physical chemical properties ................................................................... 46 4.3.1 Acid properties .................................................................................. 46 4.3.2 Thermal stability ............................................................................... 47 4.3.3 Redox properties ............................................................................... 47 4.4 Use of POM ................................................................................................ 48 4.4.1 Homogeneous catalysis..................................................................... 48 4.4.1.1 Acid catalysis ........................................................................................................ 48 4.4.1.2 Redox catalysis .................................................................................................... 49 4.4.2 Heterogeneous catalysis ................................................................... 50 4.4.2.1 Acid catalysis ........................................................................................................ 52 4.4.2.2 Redox catalysis .................................................................................................... 52 4.4.3 Commercialized process ................................................................... 53 4.4.4 Other application of POM .................................................................. 54 5. Experimental part ........................................................................................... 56 5.1 Catalytic measurement ............................................................................. 56 5.2 Treatment of the reaction mixture........................................................... 57 5.2.1 Evaporation of the solvent ................................................................ 57 5.2.2 Esterification of the reaction mixture .............................................. 57 5.2.3 Extraction of the product .................................................................. 57 5.3 Analysis of the product ............................................................................. 57 5.3.1 Analysis of the diacids ....................................................................... 57 5.3.2 Analysis of the gases ......................................................................... 58 5.4 Synthesis of the catalysts ......................................................................... 58 5.4.1 Heteropolyacids ................................................................................ 58 5.4.2 Cs salts of heteropolyacids................................................................ 59 5.5 Characterization of the catalysts .............................................................. 59 5.5.1 Characterization by FT-IR in ATR ..................................................... 59 6. Results and discussion .................................................................................... 61 6.1 Characterization ....................................................................................... 61 6.1.1 FT-IR in ATR – HPA and their salts ................................................... 61 6.1.2 FT-IR in ATR – Cs salts of HPA after the reaction ............................. 64 6.2 Oxidation of cyclohexanone with molecular oxygen – homogeneous catalysis .......................................................................................................... 66 6.2.1 Effect of the solvent ........................................................................... 66 6.2.2 Effect of the reaction time ................................................................. 67 6.2.3 Effect of the reaction temperature ................................................... 69 6.2.4 Effect of the pressure ........................................................................ 70 6.2.5 Effect of the amount of the catalyst .................................................. 71 6.2.6 Effect of the composition of the catalysts – acid vs. Cs salts ............ 74 6.2.7 Effect of the radical scavenger .......................................................... 78 6.2.8 Tests of leaching ................................................................................ 81 - SECOND PART - ................................................................................................. 84 Oxidation of cyclohexanone with hydrogen peroxide: Baeyer-Villiger oxidation 7. Baeyer – Villiger reaction ................................................................................ 85 7.1 Description of the reaction ....................................................................... 85 7.2 Caprolactone ............................................................................................. 87 7.2.1 Production and use of caprolactone ................................................. 87 7.2.2 Studied alternatives for the production of caprolactone ................. 88 8. Titanium silicalite (TS-1) ...............................................................................