Integrated Caprolactam and Hydrogen Production from Post-Consumer Nylon 6 Carpet

1. Integrated Caprolactam and Hydrogen Production from Post-Consumer Nylon 6 Carpet Robert J. Evans, John Scahill, Michael Looker, Carolyn Elam , Thomas Bash and Stefan Czernik National Renewable Energy Laboratory The 7th Annual Conference on Recycling of Fibrous Textile and Carpet Waste May 13-14, 2002

2. Background Small-Scale Approach: Integration of depolymerization and energy recovery Twin Screw Reactor Concept Proof of Concept Results Process Economics H2 by Steam Reforming Distributed Energy Generation Outline

3. Sustainability Product Stewardship Niche Opportunities Competitive Advantage Fear of Regulation Fear of Increasing Disposal Costs Collection Costs Value of Products Uncertainties in Feedstock Supply and Market for Products Permitting Issues Technical Performance Partnership Sustainability Drivers Barriers

4. Feedstocks Post manufacturing Post consumer Mixed Waste streams Coprocessing Conversion Pyrolysis Thermal Depoly Catalytic Cracking Gasification Hydrotreating Products Chemicals Gaseous fuels Refinery feedstocks Liquid fuels

5. NREL Fluid Bed Technology • Previous Concept: • Fluidized catalyst • Backing sinks to bottom and removed with catalyst • Catalyst Regeneration +process energy • Concerns: • Yield: 85% demonstrated is too low • Catalyst Recovery expense • Impurity • Capital costs

6. Industrial Ecology • Web of Materials and Energy Exchanges Among Companies and the Community • Economy of Networks versus Economy of Scale • small, complex versus large, simple • Eco-Industrial Parks • Companies Act Upon Opportunities Brought by Neighbors that Utilize Their Core Business if it Makes Economic Sense • Kalundborg Industrial Symbiosis • City in Denmark • Refinery, Power Station, High-Value Chemical Co, Fish Farm, Gypsum Board Co, City

7. Approach Challenge the Economy of Scale with the Economy of Networks Distributed Systems: -Small Units at the Point of Consumption -Shifts Economy of Scale to Number of Plants -Manufactured, Turn-Key Plants -Handle and Store Smaller Volumes of Material Process Intensification: -Combine Unit Operations -Reducing Plant Size -Improve Safety -Improve Yield/Selectivity -Innovative Equipment Integrated Polymer Recovery: Polymers and fiber via Mechanical Chemicals via Pyrolysis or Hydrolysis Energy via Gasification Carpet: N6, N66 Textiles: PET/Cotton Automotive: Urethanes, composites Blocked Processing: -Shared Equipment -Blocked Operation on Feedstocks -Timing Based on Supply and Demand -Increase the Scale of Operation Without Creating Feedstock Supply Problems

8. Concept Selectively convert one component of a mixed polymer stream to a high value product and use the rest for energy Nylon 6 Carpet: -50% N6 Face Fiber -10% Polypropylene backing -10% Styrene/butadiene latex -30% Calcium Carbonate Conditions: -Counter-Rotating, Noninter- meshing, Twin Screw Reactor -320-330 C for 1-5 minutes -K2CO3 as catalyst (1-5wt.%) -Vacuum Distillation of CPL -Extrusion of residue Over 1 billion lbs of N6 carpet thrown away each year Caprolactam sell for $0.65-.90/lb

9. Nylon 6 Carpet Recovery CO + H2 N6 Carpet Catalyst Fluid Bed Electricity Generation Twin Screw Reactor Caprolactam CaCO3 Air

10. Nylon 6 Carpet Recovery hydrocarbons N6 Carpet Catalyst Ni/Al2O3 Steam Reforming Fluid Bed Pyrolysis Twin Screw Reactor Caprolactam CaCO3 H2 + CO2 steam

16. Nylon 6 Carpet Project • NREL/ United Recycling Inc / Kemestrie Inc Cooperative Research and Development Agreement (CRADA) • Integrate Caprolactam Recovery From N6 Carpet with Recovery of Fiber From N66 Carpet • Use NFM Welding Engineers Inc. Counter-Rotating, Non-Intermeshing Twin-Screw Reactor for Depolymerization Reaction • Residues From Whole Process Feed a 5 MW Atmospheric Pressure Gasifier

17. Twin Screw Results • 8 Runs performed between January 6 and June 23, 1999 • Two Successful • Run 3: demonstrated steady state operation with synthetic feed • Run 8: demonstrated steady state operation with post consumer carpet • Problems in other runs due to instability in reactor and collection system

18. Twin Screw Reactor Non-Linear Rate Effects Independent Variables: Temperature Pressure Screw speed Feed Rate Catalyst Concentration 4 Reaction Regimes: I. No Conversion II. Low Conversion III. Stable Conversion IV. Unstable Conversion IV Dependent Variable: Melt Viscosity: Affects Catalyst Mobility Product Further Reduces Viscosity Can Result in Physical Problems III I II

19. Variables (I) • Feedstock: carpet strips • Problem: lab scale reactor and limited time • Catalyst (6 wt.% K2CO3) • Added as aqueous stream • Optimization experiment: K2CO3 better than KOH. Levels of 3 to 11% no impact on rate or purity (not true for KOH) • Time at Temperature • Bench Tests: complete conversion in 3 minutes at 350 C • TSR time = f(length, screw speed, screw design) • Due to Budget, only screw speed could be studied (not ideal) • Only could achieve 2 minutes residence time • N6 pellets – 330; Carpet – 345 C

20. Variables (II) • Screw Speed • Impacts mixing, volatile escape, melt stability, throughput, residence time • N6 pellets: 200 – 600 rpm OK • Carpet: 150 rpm; higher speeds led to foaming • Screw speed and feed rate must be decoupled • Vacuum level • Three separate vacuum lines • Influences product removal, foaming, and aerosol formation • Optimum found at 5 in Hg vacuum • Screw Design • Time permitted only one change: important for Run 8

21. Summary of Run 8 • Major problem with carpet: foaming of melt into the vent stacks • Changed reactor and screw design • Consultant present • Controlled, steady-state operation achieved (feed dependent) • 67% yield • (due to 2 minute residence time; need 3 min)

22. Purification • NREL purification process 1. CO2 precipitation of AI 2. Toluene Extraction 3. Crystallization • Just steps 2 and 3, repeated 12 times– purity from 90% to 99% in 70% yield. • Permanganate number of 300 - should be 9000. • Step 1 tried after but did not improve PN.

23. Economic Screening • Scale of Operation - 60 million lbs/year • 6000 hours of operation a year (dependent on feedstock supply and markets for Fiber products from N66 • Feedstock costs - $0.05/ lb. • Capital Costs - $20 M • Yield of Caprolactam 72% After Purification • (value = $.65/lb.) • Operating costs - $0.11/lb of product (including purification) • Internal Rate of Return - 25% Payback - 3.4 yr • Sensitivity Analysis: Scale of Operation is most critical

28. Why Hydrogen from Polymers? • H2 is a clean fuel and important chemical • Combined Heat and Power • Distributed Generation • Fuel Cells

29. Thermochemical Routes • Gasification/Water-Gas Shift • Plastics + O2  CO + H2 + Energy • CO + H2O  CO2 + H2 • Ready to commercialization • H2 Economics not competitive • Pyrolysis/Steam Reforming

30. Pyrolysis/ Reforming • Plastics+Energy  Oil + Char+ Gas • Steam Reforming of Oil • Oil + H2O  CO + H2 • CO + H2O  CO2 + H2 • Pyrolysis Conditions • Inert atmosphere • Temperature 450-550ºC • High heating rate (>1000ºC/s) • Short vapor residence time (<1 s)

31. Pyrolysis vs. Gasification • Oil is easy to transport • Locations of pyrolysis and reforming can be optimized to minimize costs of feedstock and H2 transportation • Co-products of higher value can be recovered to improve economics

32. Approach Gas & Vapors H2 CO2 Fluid Bed Pyrolysis or POX Catalytic Fluid Bed Reforming Gas Cleanup Organic solids Steam Steam

33. Steam Reformer Process Flow Vapor Cracker Reformer Char Cyclones Pyrolysis Fluid Bed Preheater

34. Yield of Hydrogen

35. Distributed Energy Resources • New energy approach adaptable to the opportunity • Simple: ON-sight generator producing emergency backup or supplementary electricity • Complex: Contain many components and systems • Generation in vicinity • Incorporate energy storage • Energy management • Combined heat and power (CHP) • Integrated with the electric grid

36. Distributed Energy Resources • Benefits • Clean energy • Lower cost electricity • Reduced price volatility • Greater, reliability and power quality • Energy and load management • Combined heat and power • Power Quality • Remote Power • Sell to Grid

37. Energy Conversion Technologies Source Reciprocating Engine Gas Turbine Microturbine Fuel Cell

38. Hydrogen and DER • CHP! • Buildings applications too • H2 can be produced and used on site for DER or transportation • Opens Markets for renewable energy • Storage to compensate for intermittency • The Hydrogen Economy

39. Summary • Successful proof of concept for twin screw reactor • Larger scale tests necessary for complete evaluation • Impurity level an issue • Economics of catalyst recovery • Market Pull vs Technology Push? • Deployment concept: Hydrogen Integration

40. Acknowledgement • Funding from NREL’s Director’s Discretionary Funding • NFM Welding Engineers Inc • Tom Bash, twin screw consultant • Merwin Brown of NREL for DER and H2 slides