Report No. 25A XYLENES SEPARATION SUPPLEMENT A by HAROLD C. RIES July 1970 A private report by the PROCESS ECONOMICS PROGRAM STANFORD RESEARCH INSTITUTE I I MENLO PARK, CALIFORNIA
CONTENTS INTRODUCTION,..,.................... 1 SUMMARY...,... 3 INDUSTRYSTATUS,.,..,....,............ 13 RECOVERY OF ORTHO-XYLENE AND ETHYLBENZENE... 19 Ortho-Xylene Recovery... 19 Ethylbenzene Recovery... 22 5 PARA-XYLENE CRYSTALLIZATION................. 23 Theory....... Review of Processes. Chevron Process... Process Description Process Discussion Cost Estimates.. Krupp Process.... Process Description Process Discussion Cost Estimates. Rhone-Poulenc Process Process Description Cost Estimates..... 23... 25... 41 43... 50... 51... 54... 54... 57... 58... 62... 62.................... 65 6 7 JAPAN GAS-CHEMICAL COMPANY PROCESS... 69 Theory... 69 Process Description... 73 Process Discussion... 89 Materials of Construction... 91 Cost Estimates... 95 ISOMERIZATION... 105 Chemistry... 105 Review of Processes... 107 Vapor Phase... 107 Liquid Phase... 123 8 COMPLETEPLANTS... 125 V
CONTENTS 9 MISCELLANEOUS PROCESSES... 129 Adsorption 129 Chromatography... 130 Fundamentals... 130 Cost Estimates... 144 Complex Formation... 151 Extractive Distillation... 153 Meta-xylene Recovery (Ccl, process)... 154 Permeation... 154 Processes Based on Reactions... 154 Alkylation-Dealkylation... 154 Chlorination-Dechlorination... 155 Hydrogenation-Dehydrogenation... 156 Sulfonation-Desulfonation... 156 Synthesis of p-xylene... 157 APPENDIX A DESIGN AND COST BASIS...,..,........ 161 APPENDIX B PHYSICAL DATA........,..,....... 167 CITED REFERENCES........................ 181 SUPPLEMENTARY REFERENCES.................... 207 PATENT REFERENCES BY COMPANY....,............. 211 vi
ILLUSTRATIONS 4.1 5.1 5.2 5.3 5.4 5.5 5.6 6.1 6.2 6.3 6.4 7.1 7.2 7.3 8:l 9.1 9.2 9.3 9.4 9.5 9.6 9.7 9.8 Effect of o-xylene Recovery on Distillation Requirements. 20 IFP p-xylene Process... 27 Phillips p-xylene Crystallization Process... 35 Crystallization Apparatus... 40... 45... 55 Rhone-Poulenc p-xylene Purification Process... 64 Equilibrium Solubility of m-xylene, BF3, and RF... 71 Effect of Temperature on Operating Conditions... 72 Japan Gas-Chemical Company Process... 81 Corrosion of Metals in Xylene, RF, and BFa Mixture... 92 Effect of Crystallization Efficiency on Octafining... 117 Effect of Product Mix on Octafining... 118 Capital Costs for Isomerization Plants... 120 Xylene9 Plant... 126 Idealized Chromatogram... 134 Comparison of Two Chromatograms... 134 Chromatogram on Bentone 34... 134 Variation of Relative Retention Volumes with Temperature in Chromatography... 142 Variation of Relative Retention Volumes at 80 C with Change of Proportion of Modifying Solvent in Chromatography... 143 Separation of Meta- and Para-xylenes by Gas Chromatography... 146 Separation of Meta- and Para-xylenes by Liquid Chromatography... 148 Effect of Separation Factor on Costs of Chromatographic Processes... 150 vii
ILLUSTRATIONS B.l Effect of Dissolved CO, on Freezing Point of Xylene9......................... 169 B.2 Vapor Pressure of HI?-BF, Mixtures at O C,......., 173 B.3 Constant Boiling Mixtures of HF-H,O-BF,........., 174 B.4 Vapor Pressure of HF'-BF,-Aromatic Systems at O C..... 175 B.5 Effect of Temperature on Decomposition of BF, Complexes.. 176 B.6 Diagram of Crystallization in the Ternary System p-xylene - m-xylene - Ccl,................ 178 viii
TABLES 3.1 3.2 3.3 3.4 5.1 5.2-5.3 5.4 5.5 5.6 5.7 5.8 5.9 5.10 5.11 6.1 6.2 The Americas....................... 15 Europe.,...,........ 16 Asia........................... 17 Soviet Bloc..,.,.,........,........ 18 Major Process Equipment and Utilities Summary....... 45 Stream Flows.................... a.. 49 Total Capital Investment.,...,.....,..... 52 Production Costs,.....,........,..... 53 Major Process Equipment and Utilities Summary....... 55 Simplified Material Balance.,.....,..,..... 55 Fixed Capital Investment................. 60 Production Costs..................... 61 Rhone-Poulenc p-xylene Purification Process Major Process Equipment List....,.......... 63 Rhone-Poulenc p-xylene Purification Process Fixed Capital Investment................. 66 Rhone-Poulenc p-xylene Purification Process Operating Costs...................... 67 Major Process Equipment and Utilities Summary....,.. 77 Major Process Equipment and Utilities Summary....... 79 ix
TABLES 6.3 6.4 6.5 6.6 6.7 6.8 6.9 6.10 7.1 7.2 9.1 9.2 9.3 9.4 Stream Flows....,.................. 85 Stream Flows.,.,,,,.,,,...,........ 87 Corrosion of Alloys in Xylene, HF, and BF, Mixture.... 93 Composition of Alloys for Corrosion Tests......... 93 Total Capital Investment............,.... 97 Total Capital Investment,..,............. 99 Production Costs..................... 101 Production Costs..................... 103 Catalyst for Vapor Phase Isomerization.......,.. 109 Molecular Sieve Catalysts for Isomerization.,..,... 113 Separation Factors for Chromatography of C, Aromatics... 137 Costs for Separation of Xylenes by Gas Chromatography... 147 Costs for Separation of Xylenes by Liquid Chromatography. 149 Dehydrocyclization of Hydrocarbons to p-xylene,..,.. 159 X