2009 Percy Julian Award Lecture
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Catalytic Applications for Enhanced Production of Transportation Fuels Soni O. Oyekan Reforming & Isom Technologist Marathon Oil 2009 NOBCChE Percy L. Julian Lecture April 14, 2009 Lecture Outline • Introduction and Acknowledgement • Overview of Oil Refining Processes • Hydroprocessing and Hydrogen • Catalytic Reforming Process • Staged Platinum/Rhenium Catalysts • Two Stage Reduction of Platinum Catalysts • Summary Introduction & Acknowledgements • Dr. Percy L. Julian’s pioneering work led to foam, paint, hormones and cortisone • ExxonMobil and George Swan for work leading to US Patent 4,436,612 and 8 other patents in late 1970s in Baton Rouge, LA • Engelhard for oil refining catalyst work in the 1980s in Edison, NJ • Marathon for opportunities to apply my expertise to oil refining processes in the past 10 years and support of my professional organization activities • Catalytic studies were conducted between 1977 and 1984 and the ideas have been incorporated into hundreds of catalytic reformers Overview of Oil Refining Processes Oil Refiners 6-3-2-1 Crack Spread ▪ 6-3-2-1 Crude Oil Crack Spread = {(Revenue from 3 barrels of gasoline + 2 barrels of diesel + 1 barrel of asphalt) – (Cost of 6 barrels of crude oil)}/6 ▪ 3-2-1 Crude Oil Crack Spreads are based on gasoline & diesel only ! ! GASOLINE DIESEL ASPHALT CRUDE OIL A Simplified Refinery Flow Diagram Sulfur Gas Sulfur Recovery Plant LPG, C3= Catalytic Hydrogen Atm NHT Reformer Crude Unit Gasoline Oil Blending Gasoline FCCU Distillate DHT Vac Fuels Unit H/C Diesel Fuels Coker Unit Coke Asphalt Marathon Garyville CCR Platformer Hydroprocessing and Hydrogen A Typical Hydrotreater Flow Diagram Hydroprocessing Reactions ✓ Sulfur, Nitrogen and Oxygenates Removal – Hydrodesulfurization is the major reaction in hydroprocessing – Hydrodenitrogenation is essential in FCC and Hydrocracker feed pre-treatment – Hydrodeoxygenation is not common, except in the processing of synthetic (coal, shale) oils and with rerun streams (MTBE, EtOH) ✓ Olefins and Aromatics Saturation – Olefin saturation for product stability and color – Aromatic saturation for solvents, transportation fuels production and FCC feed pretreatment. ✓ Hydrocracking like FCC is used for conversion of gas oils to gasoline, diesel, heating oil and jet fuel ✓ Hydroprocessing reactions consume significant amounts of hydrogen Refinery Process H2 Consumption H2 consumption is a function of: ▪ Process type ▪ Feed boiling range LSR H/T ▪ Composition NHT ▪ Sulfur DHT LP GO H/T ▪ Nitrogen DHT HP ▪ Metals H/C ▪ Oxygenates ▪ Unit pressure ▪ Unit temperature ! Avg. H2 price ~ $4/MSCF H2 consumption for a 70 MBPD Hydrocracker ~ $220 MM/yr Catalytic Reforming Processes Catalytic Naphtha Reforming Basics • Upgrade the octane of a naphtha feed to produce – High octane gasoline blending component – Hydrogen – Aromatics • Platinum reforming catalysts – Dual functionality • Hydrogenation/dehydrogenation • Acidic/isomerization • Pt/Al2O3/Cl, Pt/Re/Al2O3/Cl, Pt/Sn/Al2O3/Cl Catalytic Naphtha Reforming Basics • Hydrotreated Naphtha Feed – Sulfur < 0.3 wppm – Nitrogen < 0.2 wppm – Metals < 10 ppb – Paraffins, naphthenes and aromatics – Carbon range of C6 to C11 • Typical Process Conditions – 35 to 300 psig, 900 to 1000 F, LHSV 1.0 to 4.0, – H2/HC molar ratio of 1.5 to 6 • Principal Reactions – Naphthenes dehydrogenation – Naphthenes isomerization – Paraffin dehydrocyclization – Paraffin hydrocracking – Hydrodealkylation of aromatics – Paraffin hydogenolysis Catalytic Reforming Reactions Reference: UOP Platforming Paraffin Dehydrocyclization C2H5 M/A C2H5 C-C-C-C-C-C-C M/A Heptane, 0 RON C2H5 M Coke A M metal sites A A acid site CH3 CH3 + 4H2 M Toluene, 120 RON Adapted from G. A Mills, H. Heinemann, T. H. Milliken and A. G. Oblad, Ind. Eng. Chem. 45, 134 (1953) Semi Regen & CCR Reformers Staged Platinum/Rhenium Catalysts Platinum/Rhenium Catalysis • First assignment in Exxon was to determine the mode of promotion of Rhenium in Pt/Re catalysts • Fundamental Pt/Re catalysis and naphtha reforming process • Cleaned a 4 reactor Hydrotreating catalyst sulfiding unit for “clean sulfur” platinum/rhenium naphtha reforming studies • Isopropyl alcohol used in cleaning the unit in 8 weeks! • 4 reactors shared a common heater • Developed close working relationship with other Exxon researchers and surface characterization specialists Catalyst Test Program • Assess rhenium effects at various rhenium concentrations • Catalysts with varying rhenium content on a constant Pt catalyst – 0.3 %Pt/0.3 %Re, O.3 % Pt/0.6 % Re, relative Re/Pt ratios – 0.3 % Pt/Al2O3, 0.3 % Re/Al2O3, • Activate catalysts and characterize for start of run (SOR) coke, chloride and sulfur • Conduct test runs in a common sand bath heater with four separate reactor and product separation systems • Use the same operating conditions and naphtha feed – 935 F, 200 psig, 5000 SCF/B H2/HC • Obtain C5+, H2 and light gases (C1 – C4) yields • Characterize spent catalysts for coke, chloride and sulfur • Conduct model compound reforming studies with Heptane and methyl cyclopentane. Isothermal Unit Data for Pt/Re Catalysts Feed: P, 69.1 vol. %; N + A, 30.9, vol. % Rel C5+, Catalyst EOR EOR ! Re vol. % Activity Coke Sulfur Process Conditions; 935 F, 200 psig, H2 rate of 5000 SCF/B 1.0 70.8 85.0 8.4 0.03 ! Rel. Re = wt % Re/wt % Pt in catalyst 1.5 71.2 83.0 9.2 0.05 Test Summary 2.0 70.7 81.0 8.5 0.07 ▪ Lower coke make with higher Rhenium ▪ Lower C5+ and H2 yields 2.7 70.3 95.0 7.3 0.12 ▪ Higher sulfur retention ▪ Higher activities with Rhenium content 3.9 69.9 109.0 7.3 0.14 ▪ Different H/C ratios for the coke ▪ Shift in aromatics to BTX ! ! Commercial Simulation Unit Data Cat A 0.3 % Pt/0.3 % Re Catalyst Cat A Cat B Delta Cat B 0.3 % Pt/0.6 % Re Activity No. 72.0 96.0 +24 ! Cat B = Rel 2 ! C5+, vol. 72.0 69.3 -2.7 Feed: Light Arabian Naphtha % ! Process Conditions: 950 F, 175 psig, 3000 SCF/B, 102 RON ! Test Summary • 2.7 vol. % lower C5+ for B • Lower H2 yield • Higher C1 to C4 gas • Lower coke make Combination/Staged Catalyst Data Catalyst Catalyst A Catalyst A & Delta 0.3 Pt/0.3 Re (A) Catalyst B Activity 77.0 92.0 +15 H 2.26 2.31 +0.05 C1 – C4, wt. % 18.82 17.86 -0.96 C5+ yield, vol. % 74.30 75.50 +1.2 • Production gains for C5+ (gasoline) and H2 • $5+ MM dollars a year for a 40 MBPD Platformer • Introduced staged Pt/Re catalyst systems based on Rel. Re • Combination Pt/Re catalyst systems are now used worldwide • Determined that rhenium promoted platinum catalysis via minimization of steric hindrance for intermediate compounds • Studies led to KX-160, US Patent 4,436,612 and 8 other patents Paraffin Dehydrocyclization C H C H M/A 4 9 M 4 9 C-C-C-C-C-C-C-C-C C4H9 M M metal sites COKE A acid site A A X C3H7 , Where X is CH3, or C2H5 + 4H2 M Rhenium modifies sterically hindered intermediate compounds Two Stage Reduction of Platinum Catalysts Reforming Catalyst Reactivation • Burn coke off spent catalyst – CXHy + (x+y/4) O2 xCO2 + (y/2)H20 ! • Re-disperse agglomerated platinum and promoter metal sites • Reduce platinum and promoter – Manage water evolution – Manage reactions with hydrocarbons – Optimize reduction of platinum and promoter – Manage catalyst chloride loss • Sulfide Pt/Re catalysts to temper hyperactive sites Platinum & Rhenium Reduction PtO2 + 2H2 Pt + 2H2O ! Re2O7 + 7H2 2Re + 7H2O Past work had shown the following: ! • Platinum is reduced at 600 F • Rhenium reduction is not facile and requires temperatures > 1100 F ! Scelza et. al: TPR work shown here ! Hypothesis: Use reduced Platinum to catalyze the reduction of rhenium oxide or a promoter metal oxide Two Stage Reduction Enhances Gasoline and H2 Yields Novel activation Procedure US Patent 4,539,307 Standard 2 Stage Delta ! Red. Red. (1) Reduction at a temp between 600 F and 750 F H2, wt. % 2.44 2.52 +0.08 (2) Nitrogen purge to remove water (3) Another reduction at temp C1, wt. % 1.27 1.18 -0.09 between 900 F and 1000 F ! C2, wt. % 1.81 1.65 -0.16 ! Feed: P/N/A 46.9/37.0/16.1 Process conditions: WHSV 4 C3+C4, wt. 6.87 5.63 -1.24 200 psig, H2/HC 3, 98 % RON C5+, vol. % 82.54 83.77 +1.23 Summary • Pt/Re catalysis work by Soni Oyekan and George Swan led to increased production of hydrogen and gasoline blending components for oil refiners • The Pt/Re studies led to use of terms such as equi-molar, balanced, unbalanced and skewed by technology providers and oil refiners • Two stage reduction of platinum containing catalysts is now used worldwide in over 120 high performance catalytic reformers • Platinum catalyst inventions have enhanced economic benefits for oil refiners due to increased production of hydrogen, gasoline, diesel and jet fuel • My catalytic reforming process contributions have improved understanding of the impact of feed sulfur in naphtha reforming over platinum containing catalysts ! Thank You For Your Time 2005 Marathon Garyville Refinery Sulfur Studies of Platinum Catalysts Bimetallic Catalysts Are Sulfur Sensitive • Gasoline blending component and H2 yields are reduced drastically • Catalyst activity is significantly lowered • Process cycles are shortened for feed sulfur > 0.5 wppm • Sulfur negatively impacts productivity over Pt/Sn catalysts in CCR reformers • Worse for High rhenium Pt/Re catalysts in semi-regenerative reformers • Liquid and vapor phase sulfur guard technologies Platformer Feed Sulfur History Semi Regen & Cyclic: 1948 Pt Catalysts 10 to 20 wppm SR and CCR: 1967 Pt/Re 1970 Pt/Sn < 0.5 wppm Feed 1984 Skewed Pt/Re Sulfur, wppm < 0.2 wppm 1998: CCR & Cyclic Reduce NH4 0.1 wppm Salting Rates Platforming Technology Progression, years Low Feed Sulfur Correlation ▪ Establish a better understanding of feed sulfur in Reformers ! ! • A 4-year pilot plant studies led to feed sulfur correlations for the refining industry ! • Correlations developed for balanced and skewed Pt/Re catalysts ! ! ! ! ! ! ! ! AXENS OCTANIZER REFORMER Marathon Garyville Refinery in 2005 Marathon Garyville Hydrocracker in 2009 Coker Drums for Increased Profitability Marathon Garyville Refinery in 2009 Catalytic Reforming Reactor ! ! ! Radial Reactor with Scallops and center pipe or center screen Oil Sands Processing for Energy .