Catalysis for Biorenewables Conversion to Transportation Fuels and Bioproducts

Transcription

1 Catalysis for Biorenewables Conversion to Transportation Fuels and Bioproducts Michael R. Ladisch Laboratory of Renewable Resources Engineering Department of Agricultural and Biological Engineering Weldon School of Biomedical Engineering Purdue University National Science Foundation Workshop on Design of Catalyst Systems for Biorenewables June 23, 24, 2005

2 Acknowledgements National Science Foundation Brent Shanks, Iowa State University Jon Stewart, University of Florida Dennis Miller, Michigan State James Jackson, Michigan State

3 Opportunities and Challenges for Biorenewable Resource Engineering Production Agriculture (the source of the feedstock) Sustainable Practices Designer crops (food, fiber, industrial bioproducts and feed) Bioprocess engineering (research, design, modeling, operations) Discovery in biological/ chemical catalysis and separation sciences for design of processing facilities and hybrid biological / chemical. New modeling approaches, bottoms up design based on fundamental principles. Water, the environment and Sustainable Practices Key element of productivity, and public acceptance Communications and education Help students learn and understand the nature of energy, and the role of engineering and science in the development of the biorenewables industry

4 Biorenewables are Different Petroleum substrates High thermal stability, high volatility, low functionality; Biorenewable species, Poor thermal stability, low volatility, excess functionality. Key themes for catalysts for biorenewables selectively alter or remove functionality from biomolecules; function without degradation in water and other liquid phases at a variety of ph conditions; high activity at low temperature (where selectivity, thermal degradation are less problematic). Quoted from Miller and Jackson, Catalysis for Biorenewables Conversion,National Science Foundation, Arlington, Va., 2004

5 Technical Hurdles Designing catalysts with hydrothermal stability at high and moderate temperatures High (120 to 200 C): inorganic/organic, thermostable biomimetics Moderate (80 to 120C): thermophilic catalytic proteins or organics and/ or with acceptable activity at a low temperature (< 80 C): immobilized enzymes, Lewis acids and resistant to fouling by biological molecules Proteins, p hospholipids, oils, phenols, nucleic and organic acids Defining optimal combination of activity, selectivity, hydrothermal stability, environmental stewardship, and cost Integrating catalytic systems that combine biological (living or non-living cells), biochemical and chemical mechanisms in industrial processes Mathematically modeling bio-catalysis and processes that use it

6 Strategic Directions Use biology as a template for Catalysts: structure and function of proteins, nucleic acids, reactive intermediates generated biologically Catalytic Systems: Combinations of enzymes for biosynthesis in cells Reaction Engineering: Integration of activity, robustness, and packaging in self contained reactors Sustainability: Built in lifetime with biodegradation to environmentally compatible or recyclable components; ability of catalyst to turn on self-dis-assembly (SDA? catalytic apoptosis?) Rapid prototyping: Apply nanotechnology and microfluidics to accelerate discovery processes

7 Rapid Prototyping Initially target low temperature catalysis. Benefits: Rapid assembly of microfluidic devices Small amounts of catalysts Small amounts of substrates Reactions in diffusion limited regime Microfluidic systems and theory Impacts: Rapid screening of new catalysts Couples nanotechnology with biotechnology

8 Questions Can catalytic media be selected or developed using nanoliter sample volumes? Can nanoliter scale systems be rapidly prototyped (in minutes to hours) if only simple channels are needed? Can microfluidic flow effects be related to macroscale dispersion and mass transfer behavior encountered in larger fixed bed catalytic reactors?

9 Momentum/Mass Diffusivity Reduced velocity 2Rvε b ReSc = < 1 D m R = average radius of stationary phase v = interstitial fluid velocity ε b = void fraction between particles (extra-particulate) D m = solute diffusivity in unbounded solution (Ladisch, 2001)

10 Diffusivity (in free solution) D m = T µ R o T = temperature, K R g = radius µ o = viscosity of water at 20 C = cp = 0.01 g cm sec (based on 86 random-coil proteins, Tyn and Gusek, 1990)

11 Viscosity (between 20 to 100 C) µ = exp T T = temperature, K as T, µ (Dean, 1973)

12 C18 Surface Coating O H O H O H O H O SiO 2 Si H O H O H O H O H Cl Hydrophilic surface with a contact angle of <15 º for DI water Si Cl Cl Hydrophobic surface with a contact angle of ~ 118 º for DI water Si Si Si Si O O OO O OO O OO O O SiO 2 Si Huang et al., Biotechnology & Bioengineering

13 Hydrophobic Surface Effects Two mechanisms for understanding microfiber-directed flow 1. Corner wetting 2. Wall wetting PDMS PDMS surface (Hydrophobic) OTS OTS 1 2 Glass fiber (Hydrophilic) OTS surface (Hydrophobic)

14 Hydrophobic (θ b =75 ) Hydrophilic (θ b =5 ) Hydrophobic (θ b =150 ) Hydrophobic (θ b =150 ) Hydrophilic (θ b =5 ) Hydrophilic (θ b =5 ) Hydrophobic (θ b =75 ) Wall wetting simulation Initial patch Hydrophobic (θ b =150 ) Huang, 2004

15 2.8 micron Streptavidin beads on biotinylated BSA adsorbed onto C18 surface ~14 nm Biotinylated antibody ~2 µm Streptavidin coated microbeads (2.8 µm) Biotinylated BSA ~4 nm Hydrophobic silica surface modified with C18 Drawing not to scale.

16 Dip-coating Microfibers with Protein or Glass fiber Derivatized Particles EtOH Ultra-sonic cleaning in EtOH for 5 min Dip-coat in protein or particle slurry Glass fiber coated with particles

17 Glass Fiber Coated with Streptavidin Beads (biotin anchors beads) Streptavidin microbeads, 800 nm Biotin + Streptavidin Glass fiber pre-coated with biotin-bsa

18 Separation of avidin from BSA on Biotinylated fiber Labeled avidin (green; 10 µg/ml) and BSA (red; 10 µg/ml) liquid mixture; t=0 PDMS Glass substrate Glass fiber coated with biotinylated BSA (b) t= 5 minutes Huang et al., AICHE J.

19 Rationale Small devices rapidly fabricated with micron-sized particles having defined chemistry Provides platform for immobilizing enzymes or other biocatalytic ligands. Coupling with chromophoes and fluorescnce microscopy gives rapid assesment of molecular phenomena. Image anlysis needed for quantifying interactions / reactions. Diffusion is limiting for most interactions between target species and surfaces of media (particles, gels, pores) and diffusivity of solutes in fluid within pores is less than diffusivity in an unbounded solution Solute / adsorbent interactions in boundary layers may approximate local equilibrium (simplified Langmuir kinetics).

20 Example: Fuel Ethanol (current driver of biorenewables as an industrial feedstock) Annual U.S. ethanol production capacity from corn will reach 4 billion gallons in 2005 (RFA,2005) 1 Lignocellulosics are potential source of ethanol Estimated production cost from cellulose to be from $1.15 to $ 1.43/ gal (Wooley et al, 1999) 2 Enzyme cost contributes / gal to the production cost of ethanol (Williams and Bryan, 2005) 3 1. RFA, Ethanol report: Issue #218, Wooley, R; Ruth, M.; Glassner, D; Sheehan, J. Biotechnology Progress, Vol. 15, pp , Williams, J., and Bryan, T., Ethanol Producer Magazine, April 2005, pp

21 Pretreatment Forms Oligosaccharides Corn Fiber Pretreatment Water Liquid with Dissolved Oligosaccharides (Glucan, Xylan) Solids Kim, Mosier et al 2005

22 Composition of Corn Fiber Component % of dry weight Glucan (Cellulose) 14.3 Glucan (Starch) 23.7 Xylan/Galactan 16.8 Arabinan 10.8 Protein 11.8 Lignin 8.4 Acetyl NA Ash 0.4

23 Composition of Liquid from Corn Fiber Pretreated at 160 o C, 20 min 9.6 g of Corn Fiber ml of DI water -16% Solids in Liquid (160 g/l) Stainless steel tube reactor - total vol. : 35 ml Oligosaccahrides (Glucan,Xylan,Arabinan) Dissolved in de-ionized water (g/l) 42.4 Monosaccahrides 7.5 Proteins 4.9 HMF, Furfural 0.2

24 Catalyst Gel Type Å (Dorfner,1972) 4-10 % Crosslinked ( Macroreticular Type Å A35 (Harmer and Sun, 2001) Harmer, M.A., and Sun,Q., Applied Catalysis A: General, Vol. 221, pp.45-62, 2001 Dorfner, K., Ion exchangers : properties and applications, Ann Arbor Science, 1972, p. 34

25 Liquid from Pretreated Corn Fiber before and after Hydrolysis (Catalyst : Dowex 50WX2) HPLC chromatogram using HPX-87H column 1 1. Oligosaccharides (DP >2) 2. Cellobiose 3. Xylobiose 4 4. Glucose 5. Xylose 6. Arabinose Before Hydrolysis After Hydrolysis Retention Time (min)

26 Deactivation of Resins - Desulfonation : Irreversible deactivation of resin through loss of sulfonic groups occurring at above 120 C 7 Ion exchange capacity (meq/g catalsyt) τ A = A e c c τ 150 =213 hr t Ladisch et al, Time (hr) - Half life of 50WX2 at 150 C : 150 hrs - Fouling : by irreversible adsorption of degradation products or unremoved proteins Ladisch et al, Industrial & Engineering Chemistry Process Design and Development, Vol. 16, pp ,1977

27 Kinetic Expressions Oligosaccharides (P) k 1 k 2 Monomeric Sugars (G) Degradation Products (D) + m E 1 + n E 2 η K [ H ] k = η K [ H ] k 1 = 1 1 exp RT exp Saeman,1945, Levenspiel, 1972 k 1 /k 2 Sugar Yield RT η = rate with rate without diffusion diffusion resistance resistance = 3 φ 1 tanh φ 1 φ k= Apparent rate constant, cm 3 /g catalyst min Kim, 2005 φ = k D 1 R i eff

28 Factors affecting Sugar Yield If pore diffusion resistance is important, to increase sugar yield, k k 1 2 η 1 φ = k D 1 Ri eff R i (Resin Particle Size) D eff (Effective Diffusivity) = f (degree of cross-linking, pore size, pore tortuosity) Less Diffusion Resistance

29 Cellobiose Hydrolysis 50WX2 (2% Crosslinked Gel type) and A35 (Macroreticular( Macroreticular) G-G k 1 k 2 2 G R R HMF k 1 /k 2 =370 k 1 /k 2 =520 k 1 /k 2 =51

30 Hydrolysis of Pretreated Corn Fiber Liquid (Preconditioned using 2% A35, 50WX2, 150 o C) Remaining Oligosaccharide, Fermentable Sugars, and Sugar Loss to Degradation Products (%) Sugar Yield Degradation Products Remaining Oligosaccharides Space Time (g catalyst min/cm 3 )

31 Estimated Incremental Cost of Catalyst per Gal of EtOH Produced from Glucose - Feed Concentration : 50 g/l - Hydrolysis using 50WX2 at 150 o C, Space Time=0.85 g catalyst min/ cm 3 - Assume all fermentable sugars present as glucose Conversion :90% Sugar Yield : 80% No deactivation Deactivation Glucose Produced after 150 hr (lb glucose/ lb catalyst) Incremental Cost ( / gal Ethanol) For $2/lb catalyst For $5/lb catalyst

32 Heterogeneous Reaction: Cellulose Chain in red Cellulose Hydrolysis Nucleophile/Base Glutamic Acid Proton Donor/Acid Glutamic Acid

33 Maleic Acid pka s Succinic Acid pka s Mosier, 2005

34 Arrhenius Plot Kinetic Constants at 135, 145, 160, and 175 o C 50 mm Sulfuric Acid E a = 118 ± 37.5 KJ/gmol k o' = 1.80 x ± 1.11 x sec -1 ln(k) mm Maleic Acid E a = 72.6 ± 22.5 KJ/gmol k o' = 3.62 x 10-5 ± 1.28 x 10-5 sec Temperature -1 (K -1 )

35 Glucose from Avicel Hydrolysis mmmaleic Maleic Acid Acid: ph 1.7 Glucose Concentration (g/l) Sulfuric mm Sulfuric Acid Acid: ph % Avicel Hydrolysis Time (min.) Mosier, 2004

36 Cellobiose Hydrolysis k (min -1 ) mm Acetic Acid Control Kinetic Constants at 160 o C [H + ] Measured at 20 o C 50 mm Maleic Acid 100 mm Citric Acid 100 mm Succinic Acid R 2 = H + Concentration (mm) 50 mm Sulfuric Acid Mosier, NS; et al. Biotech. Bioeng. 79(6), , 2002;

37 Glucose Degradation Kinetic Constants at 160 o C [H + ] Measured at 20 o C Carboxyllic Acids Sulfuric Acid Control 100 mm k (min -1 ) mm 6.25 mm 25 mm 50 mm 50 mm 100 mm 200 mm H + Concentration (mm) Mosier, NS; et al. Biotech. Bioeng. 79(6), , 2002;

38 Technical Hurdles Define new catalysts for biomaterials (cost is the key driver) Heterogeneous (enzymes? Small molecules?) Homogeneous reaction systems (fixed bed catalysts?) Controlled morphologies that facilitate control of mass transfer and pore diffusion effects Synthesis, characterization of catalytic ligands based on proteins Processing of co-products into value added products (fiber, cellulosics, glycerol)

39 Technical Hurdles Designing catalysts with hydrothermal stability at high and moderate temperatures High (120 to 200 C): inorganic/organic, thermostable biomimetics Moderate (80 to 120C): thermophilic catalytic proteins or organics and/ or with acceptable activity at a low temperature (< 80 C): immobilized enzymes, Lewis acids and resistant to fouling by biological molecules Proteins, p hospholipids, oils, phenols, nucleic and organic acids Defining optimal combination of activity, selectivity, hydrothermal stability, environmental stewardship, and cost Integrating catalytic systems that combine biological (living or non-living cells), biochemical and chemical mechanisms in industrial processes Mathematically modeling bio-catalysis and processes that use it

40 Summary Biocatalysis presents opportunities for The biorenewables industry Research needed to address technical hurdles that are different from those in catalysis for petrochemicals New processes may integrate biocatalysis with catalysis.