Your SlideShare is downloading. ×

Ammonia Synthesis Catalyst Chemistry and Operator Training

2,240

Published on

Published in: Technology, Business
0 Comments
2 Likes
Statistics
Notes
  • Be the first to comment

No Downloads
Views
Total Views
2,240
On Slideshare
0
From Embeds
0
Number of Embeds
0
Actions
Shares
0
Downloads
354
Comments
0
Likes
2
Embeds 0
No embeds

Report content
Flagged as inappropriate Flag as inappropriate
Flag as inappropriate

Select your reason for flagging this presentation as inappropriate.

Cancel
No notes for slide

Transcript

  • 1. Refinery Process Stream Purification Refinery Process Catalysts Troubleshooting Refinery Process Catalyst Start-Up / Shutdown Activation Reduction In-situ Ex-situ Sulfiding Specializing in Refinery Process Catalyst Performance Evaluation Heat & Mass Balance Analysis Catalyst Remaining Life Determination Catalyst Deactivation Assessment Catalyst Performance Characterization Refining & Gas Processing & Petrochemical Industries Catalysts / Process Technology - Hydrogen Catalysts / Process Technology - Ammonia Catalyst / Process Technology - Methanol Catalysts / process Technology – Petrochemicals Specializing in the Development & Commercialization of New Technology in the Refining & Petrochemical Industries Web Site: www.GBHEnterprises.com Ammonia Synthesis Catalyst (VSG-A101) Chemistry and Operator Training by: Gerard B. Hawkins Managing Director, CEO
  • 2. Refinery Process Stream Purification Refinery Process Catalysts Troubleshooting Refinery Process Catalyst Start-Up / Shutdown Activation Reduction In-situ Ex-situ Sulfiding Specializing in Refinery Process Catalyst Performance Evaluation Heat & Mass Balance Analysis Catalyst Remaining Life Determination Catalyst Deactivation Assessment Catalyst Performance Characterization Refining & Gas Processing & Petrochemical Industries Catalysts / Process Technology - Hydrogen Catalysts / Process Technology - Ammonia Catalyst / Process Technology - Methanol Catalysts / process Technology – Petrochemicals Specializing in the Development & Commercialization of New Technology in the Refining & Petrochemical Industries Web Site: www.GBHEnterprises.com VSG-A101 Ammonia Synthesis Chemistry and Catalysis Reaction stoichiometry and thermodynamics Ammonia synthesis catalyst fundamentals Molecular mechanism and kinetics Activation and deactivation Alternative catalyst technologies Reaction stoichiometry and thermodynamics NH3 synthesis reaction N2 + 3 H2  2 NH3 DH700°K = - 52 kJ/mol Equilibrium position favors NH3 synthesis at • High pressure • Low temperature Pressure depends on capital and operating cost Temperature depends on the balance of kinetics/equilibrium P & T also depend on available catalyst activity
  • 3. Refinery Process Stream Purification Refinery Process Catalysts Troubleshooting Refinery Process Catalyst Start-Up / Shutdown Activation Reduction In-situ Ex-situ Sulfiding Specializing in Refinery Process Catalyst Performance Evaluation Heat & Mass Balance Analysis Catalyst Remaining Life Determination Catalyst Deactivation Assessment Catalyst Performance Characterization Refining & Gas Processing & Petrochemical Industries Catalysts / Process Technology - Hydrogen Catalysts / Process Technology - Ammonia Catalyst / Process Technology - Methanol Catalysts / process Technology – Petrochemicals Specializing in the Development & Commercialization of New Technology in the Refining & Petrochemical Industries Web Site: www.GBHEnterprises.com 0 5 10 15 20 25 30 35 40 50 75 100 125 150 Pressure bara NH3concentration% 380 C 400 C 420 C
  • 4. Refinery Process Stream Purification Refinery Process Catalysts Troubleshooting Refinery Process Catalyst Start-Up / Shutdown Activation Reduction In-situ Ex-situ Sulfiding Specializing in Refinery Process Catalyst Performance Evaluation Heat & Mass Balance Analysis Catalyst Remaining Life Determination Catalyst Deactivation Assessment Catalyst Performance Characterization Refining & Gas Processing & Petrochemical Industries Catalysts / Process Technology - Hydrogen Catalysts / Process Technology - Ammonia Catalyst / Process Technology - Methanol Catalysts / process Technology – Petrochemicals Specializing in the Development & Commercialization of New Technology in the Refining & Petrochemical Industries Web Site: www.GBHEnterprises.com VSG-A101 Ammonia synthesis catalyst fundamentals VSG-A101 Ammonia Synthesis Catalyst - Formulation Based on magnetite (Fe3O4) precursor Defined form and crystal structure Magnetite requires controlled reduction Pre-reduction or in situ reduction Oxygen is removed from the crystal lattice without shrinkage Produces extremely porous metallic iron structure Key in achieving a high activity catalyst Promoters boost catalyst performance VSG-A101 Ammonia Synthesis Catalyst - Requirements High catalyst activity Low sensitivity to catalyst poisons High thermal resistance Reasonable reduction time High mechanical strength and abrasion resistance
  • 5. Refinery Process Stream Purification Refinery Process Catalysts Troubleshooting Refinery Process Catalyst Start-Up / Shutdown Activation Reduction In-situ Ex-situ Sulfiding Specializing in Refinery Process Catalyst Performance Evaluation Heat & Mass Balance Analysis Catalyst Remaining Life Determination Catalyst Deactivation Assessment Catalyst Performance Characterization Refining & Gas Processing & Petrochemical Industries Catalysts / Process Technology - Hydrogen Catalysts / Process Technology - Ammonia Catalyst / Process Technology - Methanol Catalysts / process Technology – Petrochemicals Specializing in the Development & Commercialization of New Technology in the Refining & Petrochemical Industries Web Site: www.GBHEnterprises.com VSG-A101 Ammonia Synthesis Catalyst - Production Unique manufacturing process Catalyst is not made via pelleting or extrusion Components are mixed including promoters Feed is melted in an electric arc furnace Solidified melt is milled to give required shape and size distribution Melt conditions are key to produce required Fe3O4 precursor phases and morphology
  • 6. Refinery Process Stream Purification Refinery Process Catalysts Troubleshooting Refinery Process Catalyst Start-Up / Shutdown Activation Reduction In-situ Ex-situ Sulfiding Specializing in Refinery Process Catalyst Performance Evaluation Heat & Mass Balance Analysis Catalyst Remaining Life Determination Catalyst Deactivation Assessment Catalyst Performance Characterization Refining & Gas Processing & Petrochemical Industries Catalysts / Process Technology - Hydrogen Catalysts / Process Technology - Ammonia Catalyst / Process Technology - Methanol Catalysts / process Technology – Petrochemicals Specializing in the Development & Commercialization of New Technology in the Refining & Petrochemical Industries Web Site: www.GBHEnterprises.com Catalyst Type Vulcan VSG-A101 Comp J Comp J Comp H Comp H Fe 0.5 - 0.6 - 80 - 80 Fe3O4 67 - 69.5 95 12 - 13 94.5 ~10 Al2O3 2.2 - 2.6 2.5 3.3 2.1 2.8 CaO 1.4 1.8 2 2.5 1.5 2 K2O 0.6 - 0.8 0.8 1 0.6 0.8 SiO2 < 0.5 0.25 0.3 <0.2 <0.2 MgO - 0.25 0.3 - - Co - - 1 1.3 Cl <0.0001 <0.001 <0.001 <0.001 <0.001 S <0.0001 <0.001 <0.001 <0.001 <0.001 VSG-A101 Ammonia Synthesis Catalyst - Incorporation of Promoters Certain metal oxides promote activity and improve stability Small and controlled amounts Alumina and potash are the most important Al2O3 is a ‘structural’ promoter Restricts growth of iron crystallites during reduction and operation Increases thermal stability Alkali metals are ‘electronic promoters’ Greatly increase activity of the iron particles K particularly effective Other promoters include CaO, SiO2
  • 7. Refinery Process Stream Purification Refinery Process Catalysts Troubleshooting Refinery Process Catalyst Start-Up / Shutdown Activation Reduction In-situ Ex-situ Sulfiding Specializing in Refinery Process Catalyst Performance Evaluation Heat & Mass Balance Analysis Catalyst Remaining Life Determination Catalyst Deactivation Assessment Catalyst Performance Characterization Refining & Gas Processing & Petrochemical Industries Catalysts / Process Technology - Hydrogen Catalysts / Process Technology - Ammonia Catalyst / Process Technology - Methanol Catalysts / process Technology – Petrochemicals Specializing in the Development & Commercialization of New Technology in the Refining & Petrochemical Industries Web Site: www.GBHEnterprises.com Contaminants in the magnetite raw material Must be considered and controlled during manufacture Ensures optimum concentration of promoters Ammonia Synthesis Catalyst - Effect of Promoters and Stabilizers Al2O3 - stabilizes the internal surface SiO2 - stabilizes activity in presence of oxygen compounds during normal operation and reduction K2O - increases intrinsic activity of Fe particles CaO - protects the K promoter against neutralization and increases the stability against poisoning by sulfur Typical Operating Conditions Temperature 360 - 530°C (680 – 986°F) Pressure 100 - 600 bara Space velocity 1000 - 5000 hr-1 Poisons limits Oxygen and oxygen compounds normally 3 ppmv
  • 8. Refinery Process Stream Purification Refinery Process Catalysts Troubleshooting Refinery Process Catalyst Start-Up / Shutdown Activation Reduction In-situ Ex-situ Sulfiding Specializing in Refinery Process Catalyst Performance Evaluation Heat & Mass Balance Analysis Catalyst Remaining Life Determination Catalyst Deactivation Assessment Catalyst Performance Characterization Refining & Gas Processing & Petrochemical Industries Catalysts / Process Technology - Hydrogen Catalysts / Process Technology - Ammonia Catalyst / Process Technology - Methanol Catalysts / process Technology – Petrochemicals Specializing in the Development & Commercialization of New Technology in the Refining & Petrochemical Industries Web Site: www.GBHEnterprises.com Typical Converter Temperatures Converter Heat Recovery Heat recovered is that available from synthesis exotherm across synthesis beds Catalyst bed temperatures usually similar Bed 1 410 – 520°C ΔT = 110 °C Bed 2 415 – 480°C ΔT = 65 °C Bed 3 410 – 450°C ΔT = 40 °C Total Bed ΔT = Converter ΔT = 215 °C
  • 9. Refinery Process Stream Purification Refinery Process Catalysts Troubleshooting Refinery Process Catalyst Start-Up / Shutdown Activation Reduction In-situ Ex-situ Sulfiding Specializing in Refinery Process Catalyst Performance Evaluation Heat & Mass Balance Analysis Catalyst Remaining Life Determination Catalyst Deactivation Assessment Catalyst Performance Characterization Refining & Gas Processing & Petrochemical Industries Catalysts / Process Technology - Hydrogen Catalysts / Process Technology - Ammonia Catalyst / Process Technology - Methanol Catalysts / process Technology – Petrochemicals Specializing in the Development & Commercialization of New Technology in the Refining & Petrochemical Industries Web Site: www.GBHEnterprises.com VSG-A101 Ammonia Synthesis Chemistry Reaction Progress across Beds VSG-A101 Ammonia Synthesis Catalyst - Effect of Size on Activity Smaller pellets have higher activity Reaction is subject to diffusion limitations Film diffusion and pore diffusion effects Thus, smaller means higher production (closer ATE) or lower catalyst volume But higher pressure drop use either axial-radial or radial flow beds to minimize Basis of many converter internal retrofits
  • 10. Refinery Process Stream Purification Refinery Process Catalysts Troubleshooting Refinery Process Catalyst Start-Up / Shutdown Activation Reduction In-situ Ex-situ Sulfiding Specializing in Refinery Process Catalyst Performance Evaluation Heat & Mass Balance Analysis Catalyst Remaining Life Determination Catalyst Deactivation Assessment Catalyst Performance Characterization Refining & Gas Processing & Petrochemical Industries Catalysts / Process Technology - Hydrogen Catalysts / Process Technology - Ammonia Catalyst / Process Technology - Methanol Catalysts / process Technology – Petrochemicals Specializing in the Development & Commercialization of New Technology in the Refining & Petrochemical Industries Web Site: www.GBHEnterprises.com VSG-A101 Ammonia Synthesis Catalyst - Effect of Size on Activity Ammonia Synthesis Catalyst - Catalyst Size Options Size Grade Size A 1.5 - 3.0 mm B 3.0 - 4.5 mm C 3.0 - 6.0 mm D 6.0 - 10.0 mm G 14.0 - 20.0 mm
  • 11. Refinery Process Stream Purification Refinery Process Catalysts Troubleshooting Refinery Process Catalyst Start-Up / Shutdown Activation Reduction In-situ Ex-situ Sulfiding Specializing in Refinery Process Catalyst Performance Evaluation Heat & Mass Balance Analysis Catalyst Remaining Life Determination Catalyst Deactivation Assessment Catalyst Performance Characterization Refining & Gas Processing & Petrochemical Industries Catalysts / Process Technology - Hydrogen Catalysts / Process Technology - Ammonia Catalyst / Process Technology - Methanol Catalysts / process Technology – Petrochemicals Specializing in the Development & Commercialization of New Technology in the Refining & Petrochemical Industries Web Site: www.GBHEnterprises.com Molecular mechanism and kinetics Ammonia Synthesis Mechanism Dissociative adsorption of H2 Dissociative adsorption of N2 - believed to be the Rate Determining Step (RDS) Multi-step hydrogenation of adsorbed N2 Desorption of NH3
  • 12. Refinery Process Stream Purification Refinery Process Catalysts Troubleshooting Refinery Process Catalyst Start-Up / Shutdown Activation Reduction In-situ Ex-situ Sulfiding Specializing in Refinery Process Catalyst Performance Evaluation Heat & Mass Balance Analysis Catalyst Remaining Life Determination Catalyst Deactivation Assessment Catalyst Performance Characterization Refining & Gas Processing & Petrochemical Industries Catalysts / Process Technology - Hydrogen Catalysts / Process Technology - Ammonia Catalyst / Process Technology - Methanol Catalysts / process Technology – Petrochemicals Specializing in the Development & Commercialization of New Technology in the Refining & Petrochemical Industries Web Site: www.GBHEnterprises.com Ammonia Synthesis Kinetics Detailed studies on intrinsic reaction rate Influential work by Temkin et al. Actual rate subject to diffusion limitations Film diffusion and pore diffusion effects Activation and deactivation Catalyst Reduction Depends on catalyst type E.g. pre-reduced or oxide form E.g. VSG-A101, Comp H, Comp J Raise T in first bed to 350°C* (300°C # ), then slowly upwards @ 10°C/h Control exit H2O level Maintain downstream beds at 350°C* (300°C# ) NH3 synthesis initiates as the catalyst reduces Once H2O falls, heat 2nd bed and repeat
  • 13. Refinery Process Stream Purification Refinery Process Catalysts Troubleshooting Refinery Process Catalyst Start-Up / Shutdown Activation Reduction In-situ Ex-situ Sulfiding Specializing in Refinery Process Catalyst Performance Evaluation Heat & Mass Balance Analysis Catalyst Remaining Life Determination Catalyst Deactivation Assessment Catalyst Performance Characterization Refining & Gas Processing & Petrochemical Industries Catalysts / Process Technology - Hydrogen Catalysts / Process Technology - Ammonia Catalyst / Process Technology - Methanol Catalysts / process Technology – Petrochemicals Specializing in the Development & Commercialization of New Technology in the Refining & Petrochemical Industries Web Site: www.GBHEnterprises.com VSG-A101 Deactivation – Background Temperature Re-crystallization of iron surface occurs slowly Thermal sintering process Minimize operating temperature Commensurate with maintenance of conversion
  • 14. Refinery Process Stream Purification Refinery Process Catalysts Troubleshooting Refinery Process Catalyst Start-Up / Shutdown Activation Reduction In-situ Ex-situ Sulfiding Specializing in Refinery Process Catalyst Performance Evaluation Heat & Mass Balance Analysis Catalyst Remaining Life Determination Catalyst Deactivation Assessment Catalyst Performance Characterization Refining & Gas Processing & Petrochemical Industries Catalysts / Process Technology - Hydrogen Catalysts / Process Technology - Ammonia Catalyst / Process Technology - Methanol Catalysts / process Technology – Petrochemicals Specializing in the Development & Commercialization of New Technology in the Refining & Petrochemical Industries Web Site: www.GBHEnterprises.com VSG-A101 Deactivation - Common Poisons Oxygenated species (H2O, CO, CO2) Converted to H2O Sintering/re-organization of catalyst surface Temporary Low level/short duration (days) Permanent High levels/weeks to months Sulfur Incorporation of Ca promoter enhances stability of catalyst Arsenic, Antimony and Phosphorus Chlorine Formation of volatile metal chlorides Lead to KCl formation and loss of K from catalyst Physical foulants (Fe scale, etc)
  • 15. Refinery Process Stream Purification Refinery Process Catalysts Troubleshooting Refinery Process Catalyst Start-Up / Shutdown Activation Reduction In-situ Ex-situ Sulfiding Specializing in Refinery Process Catalyst Performance Evaluation Heat & Mass Balance Analysis Catalyst Remaining Life Determination Catalyst Deactivation Assessment Catalyst Performance Characterization Refining & Gas Processing & Petrochemical Industries Catalysts / Process Technology - Hydrogen Catalysts / Process Technology - Ammonia Catalyst / Process Technology - Methanol Catalysts / process Technology – Petrochemicals Specializing in the Development & Commercialization of New Technology in the Refining & Petrochemical Industries Web Site: www.GBHEnterprises.com Summary Thermodynamics, kinetics and reaction mechanism considered Features of ammonia synthesis catalysts Activation and deactivation parameters discussed Brief consideration of non-Fe based commercial catalyst

×