Enabling Extended Catalyst Lifetime in Fixed Bed Hydrotreating of Bio-Oil Alan Zacher, Mariefel Olarte, Doug Elliott Pacific Northwest National Laboratory Richland, WA, USA 6 September 2013 PNNL-SA-97972
Renewable, but Thermally unstable Corrosive Low heating value High water content Immiscible w/ HC Bio-Oil to Fuel
Challenge of bio-oil upgrading Catalyst Lifetime Catalyst/ Conditions Bio-Oil Reactor Cellulosic biomass FLUIDIZED BED REACTOR Fast Pyrolysis char gas Bio-oil H 2 HT HC Hydrotreatment Gas recycle/ reforming aqueous Diesel Jet Fuel Gasoline The strategic goal is to develop commercially viable technologies for converting biomass feedstocks into energy dense, fungible liquid fuels, such as renewable gasoline, jet fuel, and diesel, bioproducts and chemical intermediates, and bioenergy. -- Biomass Multi-Year Program Plan, DOE Bioenergy Technology Office, November 2012
Trickle Bed Reactor Bench scale hydrotreater H 2 N 2 Mass Flow Controllers Exhaust Bio-oil Pumps Wet Test Meter Knockout Pot Bio-oil Feed Sample Receivers 150 C -- 450 C 0.1 -- 1.5 LHSV 75 -- 150 atm 1-10 m 3 H 2 /L bio-oil
Back in 2011 Bio-oil hydrotreating, CoMoS, 250 C-410 C Pre-hydrotreated bio-oils (but unoptimized) catalyst fouled during upgrading ~10% Remove plug and replace with fresh catalyst extended bed life Performance decayed even with replacement
IR Techniques ATR/FTIR: fast technique for gross monitoring of functional group changes Very difficult to quantify Stabilization A no apparent changes Stabilization B changes primarily in the carbonyl (decrease) and OH (increase) regions Hydrogenation: Ru/C (1) (2)
13 C NMR analysis Loss of some functional groups typically associated with polymerization Hydrogenation: Ru/C (1) (2) Carbonyl region: Alcohol/ether region: (1) (2) Region typically associated with anomeric C in carbohydrates:
Impact of stabilization Raw Stable C Stable D Sample time (hr) 48 75 141 WHSV 0.24 0.27 0.27 Stablize none Ru Ru 1 st catalyst (RuS) Commercial Lab prep 2 nd catalyst Same in all tests Temp 170/402 171/406 170/429 Fuel density 0.85 0.84 0.84 Oil Yield 0.42 0.40 0.40 H used (g/g dry) 0.060 0.066 0.049 Oil C yield 60.7% 58.3% 59.6% Aq C yield 0.1% 0.1% 0.4% Outcome PLUG clear clear Empirical performance vs. key components Verified improvements by reactor performance Reduced bed fouling Enabled testing >200h
Trickle Bed Reactor Trickle Bed Reactor Catalyst lifetime testing Exhaust Exhaust H 2 H 2 90-170 C Ru/C 1200psi H 2 Bio-oil Pump Bio-oil Feed Sample Receivers Wet Test Meter Knockout Pot +200ppm S Bio-oil Pump Bio-oil Feed Sample Receivers Wet Test Meter Knockout Pot Hydrotreating 170-200 C RuS/C 2000psi H 2 Hydrocracking 380-420 C catalyst 2000psi H 2 Stabilization performed separately from hydrotreating/hydrocracking Stabilized oil ideally a single phase 200ppm sulfur added to stabilized oil
Performance over 700h Relatively stable yields from hydrocracking HDO activity changes over time Expected relationship of hydrogen use and oxygen content
Product composition Gasoline and diesel and fuel oil Distillate split relatively consistent ~29% constitutes Jet A cut (overlap)
Product Analysis: GC-MS Process condition: LHSV = 0.03-0.05 L/hr T = 400-410 C Oil density = 0.80 Oil density = 0.85 Methyl (not shown) and ethylphenols are early recalcitrant oxygenates.
Product Analysis: GC-MS Process condition: LHSV = 0.05-0.1 L/hr T = 400-410 C Oil density = 0.84; O wt% = 1.3%, HOS = 379h Oil density = 0.87; O wt% = 2.5%, HOS = 600h Heavier (>C 3 ) recalcitrant phenols formed later Possibly due catalyst activity loss (cracking and HDO)
Performance over 1440h Extended lifetime testing complete Expanded operating conditions evaluated Higher yield and lower oxygen content in cases Long-term catalyst defunctionalization present
Functional group analysis of bio-oil used to optimize stabilization protocols Bio-oil hydrocracking catalyst demonstrated to 60 days on stream Multiple elements needed to enable longer catalyst life Summary
Acknowledgements Department of Energy Bioenergy Technologies Office VTT Technical Research Centre of Finland Gary Neuenschwander, LJ Rotness, Sarah Burton, Teresa Lemmon, Marie Swita Questions?