PROCESS ECONOMICS PROGRAM SRI INTERNATIONAL Menlo Park, California Abstract Process Economics Program Report No. 129 REFORMING FOR BTX (June 1980) This report reviews the reforming of naphtha to produce benzene, toluene, and xylenes. The fundamentals of the reforming operations are discussed in detail. The economics were developed for reforming of two naphthas; a paraffinic and a naphthenic. Also, the effect of reforming severity on the economics is studied. LAC SF PEP'77 WS Fw Report No. 129 REFORMING FOR BTX by FRANK B. WEST Contributions by LESLIE A. CARMICHAEL STANFORD FIELD KOON LING RING WALTER SEDRIKS May 1980 A private report by the PROCESS ECONOMICS PROGRAM Menlo Park, California 94025 For detailed marketing data and information, the reader is referred to one of the SRI programs specializing-in marketing research. The CHEMICAL ECONOMICS UANDROOK Program covers most major chemicals and chemical products produced in the United States and the WORLD PETROCHEMICALS Program covers major hydrocarbons and their derivatives on a worldwide basis. In addition, the SRI DIRECTCRY OF CHEMICAL PRODUCERS services provide detailed lists of chemical producers by company, prod- uct, and plant for the United States and Western Europe. ii CONTENTS 1 INTRODUCTION . 1 2 SUMMARY . 3 3 INDUSTRY STATUS . : .................... 9 Production Capacity .................... 9 4 GENERAL PROCESS CONSIDERATIONS ............... 17 Introduction. ....................... 17 Chemistry ......................... 18 General ......................... 18 Feed Pretreating Reactions ................ 20 Reforming Reactions ................... 21 Isomerization and Dehydrogenation of Naphthenes ..... 22 Isomerization and Dehydrocyclization of Paraffins .... 23 Isomerization, Dealkylation, and Disproportionation of Aromatics ...................... 27 Isomerization ...................... 27 0 Dealkylation ....................... 27 Disproportionation and Transalkylation .......... 28 Hydrocracking of Paraffins and Naphthenes ........ 29 Coke Formation on the Catalyst .............. 30 Relative Reaction Rates and Computer Programs ...... 32 Yields ........................... 34 Reforming Severity .................... 35 UOP Bimetallic Catalyst Yield Estimates ......... 35 Analysis of Paraffin Conversions and Selectivities .... 40 Catalysts ......................... 43 General ......................... 43 Catalyst Supports .................... 45 Catalyst Dehydrogenation Activity ............ 46 Catalyst Acidity ..................... 52 0 Mass Transfer Effects and Catalyst Size ......... 54 Potential Catalyst Improvements ............. 58 Catalyst Regeneration .................. 60 Feedstocks ......................... 62 Corrosion ........................ 64 0 Start-Ups ......................... 65 Royalties ......................... 65 a ix CONTENTS 5 COMMERCIAL PROCESSES .................... 67 Feed Pretreating ...................... 67 Semiregenerative Reforming in General ........... 69 Cyclic and Continuous Reforming in General ......... 71 Licensed Reforming Processes ................ 73 Purification of Net Hydrogen Make ............. 79 Crude Reformate Stabilization ............... 80 6 PROCESS EVALUATIONS .................... 83 Introduction ........................ 83 Process Description .................... 90 Case 1 Feed Pretreatment (Section 100) .......... 92 Case 1 Reforming (Section 200, Part 1) .......... 93 Case 1 Stabilization (Section 200, Part 2) ........ 95 Case 1 Extraction of Mixed Aromatics (Section 300) .... 96 Case 1 BTX Distillation (Section 400) .......... 96 Other Cases ....................... 97 Process Discussion ..................... 111 Feedstocks and Physical Properties ............ 111 Section lOO--Hydrotreating ................ 113 Section 200 Part l--Reforming .............. 114 Section 200, Part 2--Stabilization ............ 120 Section 300 and 400--Aromatics Extraction and Distillation .................... 125 Utility Estimates for Section 200 ............ 127 Cost Estimates. ...................... 128 Capital Costs ...................... 128 Production Costs ..................... 134 Product Value ...................... 135 Optimum Conversion Level ................. 136 Optimum Feedstock .................... 137 Continuous vs. Semiregenerative Reforming ........ 138 Value of Hypothetical Improved Catalyst ......... 138 7 AROMATICS OUTLOOK ..................... 161 Introduction ........................ 161 World Crude Oil ...................... 162 U.S. Economic Acitivty and Energy Use ........... 168 NaturalGas ....................... 171 Coal.. ......................... 171 Nuclear Power ...................... 171 X CONTENTS Petroleum . 173 Synthetic Fuels . 173 Petroleum Use and Price in the United States . l . 173 Gasoline Demand and Quality in the United States . 179 Refinery Processing for Gasoline in the United States . 188 Benzene Supply and Demand Outlook in the United States . 194 CITED REFERENCES . 203 PATENT REFERENCES........................ 209 Xi ILLUSTRATIONS 4.1 Equilibrium Distribution for Systems n-Paraffin-Aromatic-Hydrogen. 26 4.2 Effect of Naphtha Composition and Desired Octane Number on the Required H2/HC No1 Ratio . 33 4.3 RON-Clear of Cg+ Reformate as a Function of %v Aromatics and Source of Feed . 36 4.4 Reformer Product Distribution . 39 4.5 Selectivity of Normal Hexane to Benzene as a Function of Temperature and Pressure . 41 4.6 Temperatures to Maintain 100 RON-Clear C5+ Reformate as a Function of Time on Stream, for Various Reforming Catalysts . 50 6.1 Naphtha Reforming for BTX l Flow Diagram . 211 6.2 Naphtha Reforming for BTX Section 200--Sheet 1 Reforming, Case 1 FlowDiagram . 213 6.3 Naphtha Reforming for BTX Section LOO--Sheet 2 H2 Purification and Stabilization, Case 1 FlowDiagram . 215 6.4 Naphtha Reforming for BTX Section 200--Sheet 1 Reforming, Case 2 a FlowDiagram . 217 6.5 Naphtha Reforming for BTX Section 200--Sheet 2 H2 Purification and Stabilization, Case 2 0 FlowDiagram . 219 6.6 Naphtha Reforming for BTX Section 200--Sheet 1 Reforming, Case 3 FlowMagram . 221 Xiii ILLUSTRATIONS 6.7 Naphtha Reforming for BTX Section 200--Sheet 2 H2 Purification and Stabilization, Case 3 FlowDiagram . 223 6.8 Effect of Plant Capacity on Total Fixed Capital . 148 6.9 Effect of Plant Capacity and Operating Level on Production Cost . 157 6.10 Effect of Conversion Level on Product Value . 159 6.11 Effect of Plant Capacity and Operating Level on Product Value . 160 7.1 Arabian Light Crude Oil Price as a Function of U.S. Inflation Rate . 167 7.2 Libyan/Arabian Light Crude Oil Price Ratio . 169 7.3 Estimated U.S. Payments for Very Low Sulfur Foreign Crude Oils . 177 7.4 U.S. Passenger Car Mileage . 181 7.5 U.S. Passenger Car Gasoline Consumption . 182 7.6 U.S. Gasoline Demand . 184 7.7 U.S. Gasoline Pool Octane Number and Lead Content . 186 7.8 Catalytic Reforming and Catalytic Cracking Capacities in the United States . 192 7.9 Catalytic Reforming, Catalytic Cracking and Gasoline Production Relative to U.S. Refining Capacity . 193 7.10 Estimated Chemical Benzene Production and Capacity in the United States . 200 7.11 Percentage of U.S. Benzene Production That Was Sold . 201 xiv TABLES a 2.1 1979 BTX Capacity and Demand ............... 3 2.2 High Severity Reforming of Naphtha Composition of Reactor Effluent .............. 6 2.3 Catalytic Reforming, High Severity Operation Summary of Economics ................... 7 3.1 Benzene Consumption Patterns--l978 ............ 10 3.2 Toluene Consumption Pattern--l978 ............. 10 3.3 Plant Capacities for Producing Benzene, Toluene, andxylenes ....................... 11 4.1 References for Reforming Reactions with Pure Components . 19 4.2 Reforming Yields from Case 1 Through 4 Material Balances Based on UOP Estimates .................. 38 4.3 Analysis of UOP Case 3 and Case 4 Mass Balances for Mol Percent Conversions of Paraffins to Aromatics and to Hydrocracking Products ................ 44 4.4 Effect of Catalyst Size, from Hettinger et al. ...... 56 6.1 Cases for Study--Reforming for BTX ............ 84 6.2 Reformer Feed Compositions ................ 85 6.3 Estimated Mid-Cycle Compositions of Net Reactor Product . 87 0 6.4 Principal Design Bases for Reactor Circuit ........ 88 6.5 Principal Design Bases for Columns ............ 91 6.6A Case Major Equipment .................. 99 0 6.6B Case MajorEquipment .................. 100 6.6C Case Major Equipment .................. 101 xv TABLES 6.7 Case 1 Severe Reforming of 20,000 bpsd of Highly Naphthenic Feed . 102 6.8 Case 2 Moderate Reforming of 20,000 bpsd of Highly Naphthenic Feed . 104 0- 6.9 Case 3 Severe Reforming of 20,870 bpsd of Highly Naphthenic Feed . 106 6.10 Case 4 Mass Balance for Moderate Reforming of 20,870 bpsd of Highly Paraffinic Feed . 108 6.11 Average Utilities Consumption for Section 200 . 110 6.12 Summary of Capital Investments--Reformingfor BTX . 140 6.13 Case 1 Capital Investment . 142 6.14 Case 2 Capital Investment . 144 aT 6.15 Case 3 Capital Investment . 146 6.16 Related Evaluations of Semiregenerative Reforming of Paraffinic Naphthas Adjusted to 20,870 bpsd Naphtha and Pep Cost Index of 290 . 149 6.17 Case 1 Detailed BTX Production Costs and Product Value . 150 6.18 Case 2 Detailed BTX Production Costs and Product Value . 152 6.19 Case 3 Detailed BTX Production Costs and Product Value . 154 6.20 Summary of Production Costs and Product Values-- 0 Reforming for BTX . 156 6.21 Effect of Scale on Capital, Production Cost, and Product Value--Reforming for BTX . 158 7.1 World Petroleum Production