F Gasoline Treating Using atalytic Distillation Texas Technology Showcase March 2003, Houston, Texas Dr. Mitchell E. Loescher
Gasoline of the Future Lead is out Olefins reduced Aromatics reduced Benzene reduced Sulfur reduced
Gasoline Desulfurization Requirements Pool sulfur specification Europe European Union 50 ppm max - 2005 10 ppm max - available 2005 - standard 2008 US, anada 30 ppm avg - 2002 to 2008 Future 15-10 -5 ppm? - 2005+
Sulfur Sources F Naphtha 200 to 3000 ppm 25 to 40% of refinery pool volume 85 to 99% of refinery pool sulfur
F Gasoline Feed omposition Sulfur, ppm 12000 10000 8000 6000 4000 2000 0 40 30 20 10 0 50 100 150 200 250 Temperature, Olefins, % Sulfur Olefins
Optimized HDS Process LN Mild HDS F 5+ GASOLINE MN Medium HDS MN/HN HN Severe HDS
onventional LN Treating 5+ ASOLINE LN FRESH AUSTI Mercaptan Removal Selective Hydrogenation Hydrogen ompression SPENT AUSTI MN/HN TREATED LN HYDROGEN Fractionate LN from F Gasoline austic wash for mercaptan removal ~90% effective Selective hydrogenation of dienes for alky/ethers ompression of makeup hydrogen
Hydrogenation / Distillation Replace trays with structured distillation packing containing catalyst Add Hydrogen Feed Vent excess Hydrogen DHydro Process Hydrogen Hydrocarbon Feed W Steam Vent Gas Treated Distillate Bottoms
DHydro Reactions Thioetherification + SH S Selective Hydrogenation + H H
DHydro Reactions Isomerization RON 118
DHydro Reactions Isomerization RON 118 150 +0.5 Hydroisomerization boosts full range F naphtha by 0.5 RON
atalytic Distillation H2 Reflux atalyst Section Drawing Vapor Wire Mesh atalyst
Optimized F Naphtha HDS LN Hydrogen DHydro F 5+ GASOLINE MN/HN HDS
onventional MN/HN HDS Make-up Hydrogen Reactors Recycle Hydrogen Light Ends Stripper W Light Ends LP Steam F Gasoline Low Sul F Gasoline
onventional Reactor Design Severity of reactor conditions set by most refractory species Temperature H 2 partial pressure Lighter sulfur species react to very high conversions All olefins exposed to the most severe conditions Reactors
onventional Fixed Bed HDS 100 onversion (%) 80 60 40 20 Total S Light S Heavy S Olefin 1 Olefin 2 0 0 0.2 0.4 0.6 0.8 1 Reactor Length Olefin 1 - with recombinant mercaptan in product Olefin 2 - w/o recombinant mercaptan
Recombinant Mercaptan Experience Mercaptan Levels fixed bed RSH RSH Level, ppm 0 2 4 6 8 10 Octane Loss (R+M)/2
Optimized F Gasoline HDS LN Mild HDS F 5+ GASOLINE MN Medium HDS MN/HN HN Severe HDS
F Gasoline Octane Distribution 92 Octane No., (R+M)/2 90 88 86 84 82 80 50 100 150 200 250 Boiling Point,
MN/HN with DHDS onditions milder than conventional fixed bed (17 barg vs 28+) > 99% HDS Heavy sulfur to bottom Light olefins to top Min octane loss(<1@ 90% HDS) F 7+ Gasoline DHDS W Off Gas Low H2 consumption Low sulfur bottoms product good for gasoline No yield loss due to cracking No makeup compressor No mid-cycle shutdown for catalyst regen No feed storage required Hydrogen
Selectivity urve onversion, Fraction 1 0.8 0.6 0.4 0.2 0 200 250 300 350 400 450 500 Temperature, F Sulfur reduction Olefin reduction Olefin saturation is higher for heavy olefins
Octane vs. arbon Number RON Linear Olefin - Linear Saturate 120 100 80 RON 60 40 20 0 5 6 7 8 9 10 11 arbon Number
Why is DTEH s octane loss lower? onventional fixed bed hydrotreaters Saturate primarily light olefins Light olefin saturation causes high octane loss DHDS Higher saturation of heavy olefins Less octane to lose in heavy olefins Lower octane loss at a given olefin reduction
Fixed Bed HDS atalyst Life? F turnaround cycle Modern refineries target 5 year cycle onventional fixed bed hydrotreaters Olefins form oligomers Oligomers form coke that fouls catalyst atalyst activity reduced Regenerate or replace catalyst Must shutdown before end of F cycle Fixed bed catalyst life insufficient
ommercial atalyst Activity for F Gasoline HDS Relative Activity 0.000 365.000 730.000 Fixed Bed HDS Days on Oil
atalyst Activity History for ommercial DHDS Units 1.6 1.4 Observed Rate onst. 1.2 1 0.8 0.6 0.4 0.2 0 0 100 200 300 400 500 600 700 800 900 1000 Days Since Start-up Irving Oil Motiva hevrontexaco
onventional Fixed Bed Unit Shutdown F unit x Sulfur Reduction Unit Untreated F Gasoline storage
onventional Unit Restart F unit x Sulfur Reduction Unit Extra apacity Required Untreated F Gasoline storage
onclusions DHydro Lowest sulfur and diolefins in LN Eliminates separate mercaptan and diolefin removal units DHDS Lowest F cycle olefin loss via HDS No cracking yield loss No diene pretreatment required No regeneration/feed storage required DHydro/DHDS Lowest overall octane loss ommercially proven Most cost effective HDS in FR F N Long catalyst life via catalytic distillation Low capital cost
Recommendations Plan for 10 ppm sulfur Evaluate full F cycle performance Include shutdown related capital cost Thank you to DOE for 1980 funding for R&L