Report No. 7 CAPROLACTAM PART I by HAROLD C. RIES ROBERT G. MULLER September 1965 A private report by the PROCESS ECONOMICS PROGRAM STANFORD RESEARCH INSTITUTE MENLO PARK. CALIFORNIA CONTENTS PART I I INTRODUCTION ......................... 1 II SUMMARY ........................... 3 Orientation ........................ 3 General Aspects ...................... 6 Technical Aspects ..................... 8 III INDUSTRY STATUS ....................... 15 IV CAPROLACTAM VIA HEXAHYDROBENZOIC ACID ............ 29 Chemistry .......................... 29 Oxidation of Toluene to Benzoic Acid ........... 29 Introduction ....................... 29 With Metallic Salt Catalysts ............... 29 With Bromine Modified Catalysts ............. 31 Hydrogenation of Benzoic Acid ............... 33 Nitrosation of Hexahydrobenzoic Acid ............ 36 Review of Processes ..................... 38 Benzoic Acid ........................ 38 Catalysts ........................ 39 Reaction Conditions ................... 40 Reaction Media ...................... 41 Reactors ......................... 42 Other Processes ..................... 43 Hexahydrobenzoic Acid ................... 45 Other Processes .................... 46 Caprolactam from Hexahydrobenzoic Acid ........... 46 Reactors ........................ 51 Process Description ..................... 51 Oxidation of Toluene to Benzoic Acid ............ 51 Hydrogenation of Benzoic Acid ............... 52 Nitrosyl Sulfuric Acid Preparation ............. 53 Nitrosation of Hexahydrobenzoic Acid ............ 54 Ammonium Sulfate Recovery ................. 54 Raw Materials ....................... 55 Materials of Construction ................. 55 Process Discussion ..................... 56 Costs ............................ 75 Capital Investment ..................... 75 Production Costs ...................... 80 iii CONTENTS -- V CAPROLACTAM BY THE PHOTONITROSATION OF CYCLOHEXANE ....... 85 Chemistry ........................... 85 Photonitrosation of Cyclohexane (PNC Process) ........ 85 Rearrangement of Cyclohexanone Oxime Hydrochloride ...... 91 Preparation of Nitrosyl Chloride ............... 92 Preparation of Nitric Oxide ................. 94 Review of Processes ...................... 96 Photonitrosation of Cyclohexane ............... 97 Photochemical Lamps and Reactor .............. 98 Rearrangement of Cyclohexanone Oxime ............. 101 Caprolactam Purification ................... 102 Nitrosyl Chloride Preparation ................ 103 Nitric Oxide Preparation ................... 104 Process Description ...................... 105 Preparation of Nitrosyl Chloride ............... 106 Photonitrosation of Cyclohexane ............... 107 Rearrangement of Oxime .................... 107 Ammonium Sulfate Recovery .................. 108 Caprolactam Recovery & Purification ............. 108 Raw Materials ........................ 109 Materials of Construction .................. 109 costs ............................. 121 Capital Investment ...................... 121 Production Costs ....................... 121 Variations Affecting Costs ................. 129 VI CAPROLACTAM FROM NITROCYCLOHEXANE ............... 133 Chemistry ........................... 133 Nitration of Cyclohexane ................... 133 Reduction of Nitrocyclohexane to Cyclohexanone Oxime ..... 137 Nitrocyclohexane Directly to Caprolactam ........... 140 Rearrangement of Cyclohexanone Oxime ............. 141 Review of Processes ...................... 141 Nitration of Cyclohexane ................... 143 Liquid Phase Nitration ................... 144 Vapor Phase Nitration ................... 145 Recovery of Nitrogen Oxides from Off-Gas ........... 148 Purification of Nitrocyclohexane ............... 149 Reduction of Nitrocyclohexane to Cyclohexanone Oxime ..... 149 iv CONTENTS Process Description ..................... 150 Nitration of Cyclohexane .................. 151 Nitrocyclohexane Recovery ................. 151 Reduction of Nitrocyclohexane ............... 152 Cyclohexanone Oxime Recovery ................ 153 Rearrangement of Oxime ................... 154 Caprolactam Purification and Sulfate Recovery ....... 154 Adipic Acid Recovery and Purification ........... 154 Nitric Acid Recovery .................... 156 Raw Materials ....................... 156 Materials of Construction ................. 169 costs ............................ 169 Capital Investment ..................... 169 Production Costs ...................... 169 By-Product Production and Credits ............ 174 Variations Affecting Costs ............... 178 VII FINAL PURIFICATION OF CAPROLACTAM . 183 APPENDIX A Design and Cost Basis . 189 APPENDIX B Physical Data . 193 APPENDIX C Raw Material and Product Specifications . 195 Cited References . 199 Supplementary References . 222 ILLUSTRATIONS 1 Caprolactam Processes ...................... 5 2 Caprolactam in Western Europe .................. 26 3 Caprolactam Plant Capacity ................... 26 4 Effect of Ionic Bromine on Oxygen Consumption .......... 32 35 5 Benzoic Acid Hydrogenation (Rylander --et al.). .......... 6 Caprolactam Via Hexahydrobenzoic Acid .............. 65 7 Proposed Reaction Mechanism by Ito for Photonitrosation of Cyclohexane Using Nitrosyl Chloride ............... 87 8 Caprolactam by PNC Process ................... 111 9 Caprolactam Purification and Sulfate Recovery from PNC Process. 113 10 Reaction Mechanism Proposed by Titov for the Nitration of Cyclohexane ........................... 135 11 Proposed Reaction Scheme for the Reduction of Nitrocyclohexane by Doumani and Coe ....................... 139 12 Effect of Temperature on the Liquid Phase Nitration of Cyclohexane Based on Data of Gut --et al. ............. 146 13 Caprolactam from Nitrocyclohexane ................ 159 14 Effect of Nitric Acid Consumption on Caprolactam Cost ...... 177 15 Effect. of Nitration Temperature on Adipic Acid By-Product and Caprolactam Cost ...................... 179 16 Effect of By-Product prices on Caprolactam Cost ......... 181 vii TABLES 1 Process Index . 4 2 Plant Capacities Americas . 17 3 Plant Capacities Europe . 19 4 Plant Capacities Middle and Far East . 21 5 Plant Capacities Soviet Bloc.................. 23 6 World Capacity for Caprolactam . , . , . , . 27 7 Hexahydrobenzoic Arid by Toluene Process--Sections 100 and 200 Major Process Equipment List . , . , . , . , . 59 8 Caprolactam from Hexahydrobenzoic Acid--Sections 300 and 400 Major Process Equipment List . , , . , . 63 9 Hexahydrobenzoic Acid from Toluene Stream Flows . 67 10 Caprolactam from Hexahydrobenzoic Acid Stream Flows . 69 11 Caprolactam from Hexahydrobenzoic Acid--Section 500 Major Process Equipment List . , . , , . 73 12 Caprolactam from Hexahydrobenzoic Acid Process Unit and Utilities Investment . , . 77 13 Caprolactam from Hexahydrobenzoic Acid Total Capital Investment . 79 14 Caprolactam from Hexahydrobenzoic Acid Production Costs . , . 81 15 Caprolactam by PNC Process--Sections 100 and 200 Major Process Equipment List . , . 111 ix TABLES 16 Caprolactam by PNC Process--Sections 300 and 400 Major Process Equipment List . 113 17 Caprolactam by PNC Process Stream Flows . 115 18 Caprolactam by PNC Process Process Unit and Utilities Investment . 123 19 Caprolactam by PNC Process Total Capital Investment . , . 125 20 Caprolactam by PNC Process Production Costs . , . 127 21 Caprolactam by Nitrocyclohexane Process Major Process Equipment List . 157 22 Caprolactam from Nitrocyclohexane Stream Flows . , . 161 23 Caprolactam from Nitrocyclohexane Process Unit and Utilities Investment . 171 24 Caprolactam from Nitrocyclohexane Total Capital Investment . 173 25 Caprolactam from Nitrocyclohexane Production Costs , . 175 X .