Integrated Hydropyrolysis and Hydroconversion Process for Production of Gasoline and Diesel Fuel from Biomass Extended Abstract 2009 AICHE

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1 Integrated Hydropyrolysis and Hydroconversion Process for Production of Gasoline and Diesel Fuel from Biomass Extended Abstract 2009 AICHE 2009 Gas Technology Institute All rights reserved. Terry Marker, Larry Felix, and Martin Linck - Gas Technology Institute INTRODUCTION There is considerable worldwide interest in developing technologies for converting lignocellulosic biomass into transportation fuels as a way to reduce dependence on foreign oil and reduce fossil green house gas emissions. The DOE has estimated that 1 Billion tons per year of biomass (1) is available for conversion in the United States. If all of that U.S. biomass was converted to liquid fuels, a large portion of imported crude used to make transportation fuels could be eliminated, as shown in Figure 1. MMBPD Transportation Fuels Potential from Vegetable Oil Potential from LignoCellulosic domestic foreign Figure 1. Potential for US Fuel Production from Lignocellulosic Biomass. Fast pyrolysis (2)(3)(4) has long been advocated as a method for converting lignocellulosic biomass to liquids which could then be burned to make electricity or be transported to oil refineries for processing into fungible fuels. However, fast pyrolysis oil possesses many undesirable properties including a high total acid number (TAN ~200), low heating value (~6560 BTU/lb), high oxygen content (~40%), chemical instability, high water content (20%) and incompatibility with petroleum fractions. Inherent low energy density makes pyrolysis oil expensive to transport and the high TAN makes it metallurgically incompatible with conventional transport vessels and refinery hydroconversion equipment, both designed for feeds with TAN s less than 2. In addition to these undesirable properties, pyrolysis oil is not miscible with petroleum fractions and if added into existing refinery equipment (hydrotreaters or hydrocrackers) will require a separate pyrolysis-oil feed system. Thus, pyrolysis oil is chemically far from a crude oil replacement. 1

2 Upgrading pyrolysis oil (5)(6)(7) through hydroconversion has been demonstrated in pilot testing but is carried out at low space velocities ( LHSV), high pressures ( psig) with short run times. Finally, pyrolysis oils upgraded to remove oxygen and make gasoline and diesel typically requires an additional 3-4 wt.% hydrogen, on a pyrolysis oil feed basis. Indeed, the conditions required for upgrading pyrolysis oil make it similar in cost to upgrading petroleum resid. When pyrolysis oil is upgraded to remove the oxygen, the finished hydrocarbon yield is 26-30% of the starting biomass (7) A better approach for biomass conversion is the integrated hydropyrolysis and hydroconversion (IH 2 ) of biomass to directly produce fungible gasoline and diesel fuel or blending components. IH 2 is carried out in two integrated stages, as shown in Figure 2. The first stage is a medium pressure, catalytically-assisted, fast hydropyrolysis step completed in a fluid bed under moderate hydrogen pressure. Vapors from the first stage pass directly to a second stage hydroconversion step where a hydrodeoxygenation catalyst removes all remaining oxygen and produces gasoline and diesel boiling range material. All the process steps are completed at essentially the same pressure (except for pressure drop across the equipment) so that compression costs are minimized. A unique feature of this process is that all the hydrogen required for the IH 2 process is produced by reforming the C 1 -C 3 hydrocarbons so no additional hydrogen is required. Initial economic analysis suggests that the IH 2 process reduces handling, transportation, processing, and has about the same capital costs as pyrolysis alone, making it a much more attractive approach. Figure 2. IH 2 system schematic, showing overall process flow. The IH 2 process builds on GTI s knowledge base of fluidized bed design, feeding biomass into high pressure fluid bed reactors, glass ceramic catalysts (8)(9) and GTI biomass hydropyrolysis work carried out in the early 1980 s (10)(11) The design basis for the IH 2 process is based on new R&D, described below, which has recently been completed at GTI using modern catalysts. 2

3 EXPERIMENTAL The wood feed used for the IH 2 proof of principle experiments has the analysis shown in Table 1. Table 1- Wood Feedstock Analysis Component Proximate Analysis Ultimate Analysis( dry basis) Moisture % 3.89 Ash % %C %H 5.82 %S 0.03 %N 0.11 %Oxygen (by difference) The IH 2 proof-of-concept testing was carried out in a 2 in. (5 cm) diameter pressurized fluid bed hydropyrolysis first stage that incorporated an internal char filter (2 micron pore size) followed by a fixed bed integrated hydroconversion second stage. An existing small scale GTI gasifier was reconfigured for use in the hydropyrolysis R&D effort. A key modification was the addition of a hydroconversion reactor used as a fixed catalyst bed located directly downstream of the hydropyrolysis unit and process filter. Figure 3 shows the IH 2 pilot scale system. The catalyst used in the 2 nd stage fixed bed hydroconversion reactor was a sulfided CRI/Criterion Inc. CoMo catalyst. The CRI/Criterion Inc. catalyst worked well to remove the oxygen from hydropyrolysis vapors and the finished product was determined to be primarily in the gasoline boiling range. Data resulting from the IH 2 process development work are presented in Table 2. These data reveal that good yields of negligibly low oxygen content, light hydrocarbon product is produced from the IH 2 process and the proper amount of C 1 -C 3 light ends is produced which can be reformed to produce all the H 2 required by the process to complete hydrogenation. GTI has intellectual property related to the IH 2 process. Figure 3. The GTI IH 2 proof-of-concept unit. 3

4 Table 2- GTI IH 2 Process Experimental Results Component/Compound Test 1 Feedstock Wood HC liquid yield, % % Oxygen in liquid <1 % Gasoline boiling range in liquid 92 % Diesel boiling range in liquid 8 % Char 10 % CO x 14 % C 1 -C 3 14 % Water 33 % C in water phase 0.2 One of the important aspects of the IH 2 process is the use of proper catalyst and conditions so the deoxygenation reactions, which remove oxygen from the structure, are balanced between hydrodeoxygenation (where hydrogen reacts with oxygen to make water) and decarbonylation (where oxygen is removed as CO) + decarboxylation (where oxygen is removed as CO 2 ). If all the oxygen was removed by making water, all the carbon would be retained and liquid yields would be maximized but a great excess of hydrogen would be needed. The use of large amounts of imported hydrogen is expensive and undesirable from a LCA standpoint as hydrogen is typically made from natural gas and hydrogen production is energy intensive. In the other extreme, if all the oxygen is removed by decarboxylation (CO 2 removal) or decarbonylation (CO removal) liquid yields would be significantly reduced since carbon is removed with the CO or CO 2. In the IH 2 process, the goal is to balance the CO 2 /H 2 O so roughly the same amount of each component is made after the CO has been water gas shifted. When balanced levels of CO 2 and H 2 O are made, then all hydrogen required for the process can be produced from reforming the C 1 -C 3 gas. Our proof of principle experiments have shown that balancing the CO 2 and H 2 O is an attainable goal as shown in Table 3. Table 3- Test 1, Wt.% CO-CO 2 and H 2 O Component Test 1-before water gas shift Test 1 after water gas shift CO CO H 2 O H Wt.% (H 2 O/CO 2 ) 1.1 In separate experiments we have also shown that the hydroconversion catalyst performs the water gas shift to generate in-situ H 2 while also carrying out the deoxygenation reaction, when the H 2 velocity is adjusted. This is shown in Table 4. Table 4 - Effect of Water-Gas Shift Reactions in Pyrolysis and the IH 2 Process Component Pyrolysis IH 2 Wt% (CO 2 /CO) Although the GTI IH 2 Process is unique, it is derived from a logical approach, built upon several well established principles: In pyrolytic processes, rapid heating of biomass maximizes liquid yield, Hydroconversion reduces the oxygen content in liquid biomass products resulting from hydropyrolysis or pyrolysis, Hydrocracking of polynuclear aromatic components (formed during standard pyrolysis) is expensive and if possible, should be avoided. 4

5 The water analysis is shown in Table 2. The water produced by the IH 2 Process varies with conditions but generally exhibits low hydrocarbon contamination as indicated by the low level of carbon in the water phase (0.2%). Although further testing is required, it is expected that after cleanup, the water from the process can be recycled, making the process completely self sufficient in water as well as hydrogen. Several encouraging experimental observations should also be noted. No increase in pressure drop was noted across the filter as the test progressed, whereas earlier fluid-bed fast pyrolysis tests showed a significant increase in filter pressure drop during similar test periods. This shows the stability of hydropyrolysis product compared to pyrolysis products. The char and catalyst recovered after the experiment remained finely divided and no big agglomerates were found. Also, water and hydrocarbon form separate phases and the hydrocarbon liquids formed by the IH 2 process are miscible with petroleum-based fuels. Note that at present, only proof of principle experiments have been completed, so further optimization of the process is expected. RESULTS AND DISCUSSION Proof of principle work has shown that the IH 2 process concept represents a major technological advance from the current state of the art in pyrolysis or pyrolysis followed by upgrading as shown by a comparison of these technologies in Table 5. Table 5- Overall Technology/Process comparison Fast Pyrolysis Fast Pyrolysis IH 2 + Hydroconversion + Reforming Product properties Poor Excellent Excellent External H 2 required None 3% None Capital costs Medium High Medium Transportation costs Medium High Low A more detailed comparison of pyrolysis with IH 2 is presented in Table 6. IH 2 is similar in cost to a typical pyrolysis unit. In the IH 2 process an extra reactor and integrated steam reformer are added but the fluid bed combustor and quench system, which are typically present in pyrolysis systems, are eliminated. Because of the stability of the intermediate product, integrated hydropyrolysis plus hydroconversion has no problem with hot filtering to remove metals and char and protect second stage catalyst. The viability of hot filtering was demonstrated in our proof of principle experiments which showed no filter pressure drop build up or filter fouling. Table 6- Detailed Technology/Process Comparison Fast Pyrolysis IH 2 Heat of reaction Endothermic +300J/g Exothermic J/g Quench Required No Hot filtering Difficult Straightforward Pressure 25psia psia Integration with upgrading none Yes H 2 requirements for upgrading 3% None 5

6 One of the advantages of the IH 2 process is the direct production of high-valued, high energy content fungible hydrocarbon products with negligible oxygen content. Measured product properties are presented in Table 7. Table 7 Product Property Comparison Fast Pyrolysis Oil IH 2 Product % Oxygen 50 < 1.0 % Water 20 < 0.1 Total acid number (TAN) 200 < 2 Stability Poor Excellent C F Non-distillable F Non-distillable F+ Non-distillable < 1.0 Compatibility with crude oil or refinery products None Excellent Heating value BTU/lb Relative transportation cost From a standpoint of process chemistry, the IH 2 process for conversion of biorenewables to fungible fuels is a fundamentally superior approach, especially when compared to fast pyrolysis plus upgrading. Pyrolysis, including fast pyrolysis, is an uncontrolled thermal reaction which produces a highly oxygenated oil containing condensed polynuclear aromatics, high molecular weight polymers, unstable free radicals and olefins which were not present in the original biomass. Once these compounds are formed, they are expensive and difficult to upgrade, with the upgrading process requiring high H 2 addition, high pressures and low space velocities. Because of the multi-ring aromatics, pyrolysis oil hydroconversion becomes similar in cost and complexity to the hydroconversion of petroleum resid. The high acid number of fast pyrolysis oils (TAN ~200) makes their processing in standard oil refinery hydroconversion reactors nearly impossible because these reactors are designed for feeds with acids numbers of less than 2. Furthermore, mild hydroprocessing of fast pyrolysis oil to reduce the TAN is not realistic until the oxygen is almost totally removed from the product oil, otherwise significant hydrocarbon product is lost to the water phase, and the water produced requires extensive cleanup. With IH 2, no undesirable polynuclear aromatics, olefins, or reactive free radicals are formed because high partial pressures of hydrogen and catalyst are available during the first stage of processing. In this stage, biomass is fed into the fluid bed reactor where it liquefies, vaporizes and reacts to partially remove oxygen and sever molecules where oxygen is removed. Then, hot vapors from the first stage of hydropyrolysis are directly conveyed to the hydroconversion reactor where the remaining oxygen is removed. The molecules are thereby converted into fungible low boiling gasoline and diesel range liquids. Hydropyrolysis plus hydroconverson is not hydrocracking because few carbon to carbon bonds are broken. It is properly described as hydrotreating where heteroatoms are removed. Because we carry out hydrotreating to remove oxygen atoms, the reactions can be completed at moderate pressures of psia, instead of the high pressures which are required in hydrocracking of VGO, resid or fast pyrolysis oils. Because of the stable molecules produced in the first stage, high temperature char filtration, located between the first and second stage, can be employed to remove char and metals from the vapors without fear of introducing coking or experiencing irreversible pressure drop, a common problem in attempts at hot filtration in conventional fast pyrolysis. In proof of principle 6

7 experiments, no pressure drop problems or coking has been found on the interstage filter. The filter therefore protects the second stage catalyst from ash and catalyst poisons. The IH 2 process approach reduces transportation costs to less than one third of that required in the pyrolysis plus upgrading approach because all the water and oxygen are removed within the process and stable, high energy density fungible hydrocarbons are created that can be immediately transported to refineries for blending. In GTI research to date, it has been found the IH 2 process proceeds by removing oxygen from the biomass structure, causing molecules to break where the oxygen is removed. The effect of the oxygen removal is shown for a typical lignin structure shown in Figure 4. The result is light gasoline and diesel boiling range product with less than 2% oxygen which is not miscible with the separate water phase. The IH 2 process incorporates a number of novel process features that are enumerated in Table 8. Figure 4. Coniferous lignin structure showing typical oxygen bond breaking points for the IH 2 process. Table 8 Novel Features of the Overall IH 2 Process 1 Two-stage integrated fast hydropyrolysis + hydroconversion 2 Balanced CO x and H 2 O production with integrated steam reforming 3 Conversion of first stage CO + H 2 O to H 2 + CO 2 by the second stage catalyst 4 Unique, attrition resistant first stage hydropyrolysis catalyst to produce uncontaminated char-ash 5 Self-contained system with no requirements for external hydrogen or methane 7

8 As Poured Cerammed Crushed ~150µm Reduced Another unique aspect of the IH 2 process is the potential use of an attrition-resistant glass ceramic catalyst in the hydropyrolysis stage of the process. Glass ceramic catalysts were originally developed for the decomposition of tar in biomass gasification applications under US DOE Cooperative Agreement DE-FG36- (amorphous glass) (microcrystalline ceramic) Crushed 04GO This catalyst is being adapted for use in the first stage Figure 5. A glass-ceramic catalyst containing 30 wt.% NiO of the hydropyrolysis process and because of its attrition resistance it is expected to effectively grind char and ash into a fine dust which is conveyed out of the hydropyrolysis reactor. Figure 5 shows examples of the glass ceramic catalysts produced at GTI. LIFE CYCLE ANALYSIS A life-cycle analysis (LCA) of the integrated hydropyrolysis and hydroconversion process was completed by Professor Shonnard based on the proof of principle results (10). Professor Shonnard is Deputy Director of Sustainable Futures Institute, and author of a widely used LCA text book, Green Engineering: Environmentally Conscious Design of Chemical Processes, (11) and expert in LCA analysis. This analysis reveals the IH 2 process has the potential to reduce greenhouse gas emissions by over 90%, for fuels made by this process, as shown in Figure 6. Figure 6 compares the IH 2 technology to other published LCA (12) from other technology approaches. Hydropyrolysis +Hydroconversion Butanol Pyrolysis plus Upgrading Gasification +FT max min Gasification +MTG Figure 6. Comparison of % Greenhouse Gas Reduction for different production strategies (with gasoline from petroleum as a basis). 8

9 ECONOMICS The conversion of biomass to fungible gasoline and diesel fuels through the technology we propose, balanced IH 2, will be a disruptive, or game-changing technology as it circumvents the barriers which have limited conventional fast pyrolysis-based and biological approaches to the conversion of biomass to fungible transportation fuels. Commercialization of this technology provides a path for significantly reducing our dependence on foreign sources of oil. Compared to other processes that employ biomass to create fungible fuels, for example, fast pyrolysis plus upgrading, IH 2 offers three key technical and economic advantages: 1. No external source of hydrogen or methane is required for upgrading, 2. IH 2 offers a way of directly producing high quality, fungible hydrocarbon products, with negligible TAN and low oxygen content, 3. Lower capital and operating costs, compared to other biomass-to-fuel technologies. The first two advantages translate directly into the third advantage, better economics. An economic study has been completed of the IH 2 process based on the results of initial GTI testing. Key assumptions are presented in Table 9. Table 9. Economic Assumptions Biomass $/ton 46 Gasoline and diesel $/bbl 100 Crude oil $/bbl 80 Char $/ton (carbon credit) 46 Return on investment or ROI 10% Because of the variety of sizes and feedstocks which could be utilized for this technology, economic analyses were carried out for commercial process units of several sizes and feeds. These are presented in Table 10. Table 10 - Integrated Hydropyrolysis + Hydroconversion + Reformer Economics Feed rate 500t/d 1000t/d 2000t/d 1000t/d 2000t/d Feedstock wood wood wood corn stover corn stover Capital Cost, ISBL (inside battery limits), $MM EEC (estimated erected cost), $MM Total Capital Employed, $MM Full Cost of Production (FCOP)$/gal Full cost of production+roi, $/gal Payout period, yr NPV(Net present Value), $MM These economic projections show that the IH 2 process is economically viable in the range of 500t/d to 2000t/day for $46/ton biomass and $80/bbl crude oil. If crude oil prices increase further, or if biomass is available at lower prices (which may be the case for forest clearing operations aimed at reducing forest fires), even smaller scale IH 2 units could demonstrate economically viability. If CO 2 credits are included or alternative fuels credits are included the economics will become even better. 9

10 Table 11 presents a comparison of economics of pyrolysis plus upgrading versus the IH 2 process and reveals that the IH 2 process possesses a clear advantage because there is no H 2 cost (as it is made in the integrated reformer) and the hydroconversion step is also much lower in capital cost. Table 11. Economic Comparison- 2000t/d wood feed IH 2 Process Pyrolysis plus Upgrading ISBL, Capital Cost $MM EEC,$MM H 2 Costs, $/gal -.45 Full Cost of Production DOE 2007 BC State of technology DOE 2012 BC target (FCOP)$/gal FCOP + ROI, $/gal $/gallon ethanol equivalent (13) DOE Tech Sheet Thermochemical Conversion of Biomass to Transportation Fuels: Pyrolysis Oil to Gasoline, May 2009 The IH 2 technology is more economically attractive than fast pyrolysis plus upgrading or ethanol production through fermentation. It is the optimal technology choice for biomass conversion. CONCLUSIONS GTI has completed proof of principle work which identifies a significant, new, economically attractive approach for converting biomass directly to gasoline and diesel fuel or blending components. Additional work is needed to fully demonstrate and commercialize the process. ACKNOWLEDGEMENT GTI would like to acknowledge the help of CRI/Criterion Inc. in providing much of the catalyst used in these studies. REFERENCES (1) Perlack,R,.D., Wright,L.L., Turhollow,A.F., Graham,R.L. Stokes,B.J., Erbach,D.C. Biomass as Feedstock for a Bioenergy and Bioproducts Industry: The Technical feasibility of a Billion-Ton Annual Supply DOE-GO (2) Hulet, Craig, Briens,C., Berruti, F., Chan E.W. A Review of Short Residence Time Cracking Processes International Journal of Chemical Reactor Engineering, Vol 3 (2005) (3) Bridgwater,A.V., Meier D.,Radlein D. An overview of Fast Pyrolysis of Biomass. Organic Geochemistry 30, ,1999 (4) Bridgwater A,V.,Peacoke G.V.C. Fast Pyrolysis processes for biomass Renewable and Sustainable Energy Reviews 4,1-73,2000 (5) Qi,Z.,,Jie, C. Tiejun,W.,Ying, X., Review of Biomass Pyrolysis Oil Properties and Upgrading Research Energy Conversion and management 48 (2007) (6) Elliott,D.C., Neuenschwander, D.G. Liquid fuel by low severity hydrotreating of biocrude. Developments in thermochemical biomass conversion. London: Blackie Academic and Professional 1996 p (7) Brown, R., Holmgren J, Fast Pyrolysis Oil and Bio-Oil Upgrading, Oct 4,2006 presentation 10

11 (8) Bodle W.W., Wright, K.A, Hydropyrolysis of Biomass and Related Materials for the Production of Liquids, Symposium Papers Energy from Biomass and Wastes VI, Sponsored by the Institute of Gas Technology Lake Buena Vista Fla., Jan 25-29, 1982, (9) Fujita,R.K. W.W.Bodle,Yuen, P.C., Hydropyrolysis of Biomass to Produce Liquid Hydrocarbon Fuels. Final Report. Biomass Alternative Fuels Program DE Springfield Va, National Technical Information Service, 1982 (10) Felix,L. G., Rue,David M.,Slimane,Rachid,B.,US Patent 7,449,424 Method of Producing Catalytically Attractive Materials, Assigned to Gas Technology institute, Nov 11,2008 (11) Kuhn, J. N., Zhao, Z., Ozkan, U. M., Felix, L. G., Slimane, R. B., Ni-Olivine Catalysts for Tar Removal in Hydrogen-Rich Streams, Catalysts for Biorenewable Energy Applications, Catalysis & Surface Science Secretariat, Paper 10, Presented at the 233 rd National Meeting and Exposition of the American Chemical Society, March 25-29, 2007, Chicago (12) Shonnard, D, LCA Analysis of Integrated Hydropyrolsis and Hydroconversion Process, Private communication to T.Marker June 2009 (13) Allen, D.T. and Shonnard, D.R., Green Engineering: Environmentally Conscious Design of Chemical Processes, published by Prentice-Hall, 2002 (14) Hsu,D., Biofuels Beyond Ethanol, NREL Public meeting of the Biomass Research and Development Technical Advisory committee, Sept 9,