Upgrading of Bio-oils from Biomass with Catalytic Hydrotreatment

Transcription

1 UGent Francqui Chair 2013 / 4th Lecture Upgrading of Bio-oils from Biomass with Catalytic Hydrotreatment Nikos Papayannakos, Professor National Technical University of Athens School of Chemical Engineering Unit of Hydrocarbons and Biofuels Processing

2 utline Introduction Ligocellulosic Biomass Conversion to Liquid Bio-ils Hydrotreatment of Bio-ils Pre-treatment Post-treatment Co-Processing Current trends in research Conclusions

3 UGent/FCh13/3L UGent/FCh13/4L Biomass Biomass : Sustainable Feedstock Can replace diminishing fossil Fuels to produce Energy Chemicals Three General Classes of feedstocks derived from Biomass ils Starchy Lignocellulosic

4 Starchy Feedstocks Polysaccharides with a-glycosidic bonds Structural Units : Glucose Solar Energy Store Amylopectin wt % Linkages α (1-6) Amylose wt % Linkages α (1-4) Easily hydrolyzed into the constituent sugar monomers BIETHANL 1 st Generation Biofuel Disadvantages of 1 st Gen. Biofuels The easily processed Sugars and Triglycerides are only a small part of the Biomass Poor Energy Yields

5 Lignocellulosic Biomass Lignocellulosic biomass is : Inexpensive and The most abundant class of Biomass Present in all plants contributing structural integrity Lignocellulosic Biomass is comprised of : Cellulose is a crystalline, strong and resistant to hydrolysis Polysaccharide with b (1-4) glycosidic linkages wt % Hemicellulose is a Polysaccharide with a random Structure and little strength. It is easily hydrolyzed by dilute acids, bases and enzymes wt % Lignin is an amorphous Polymer composed of methoxylated phenylpropane structures wt %

6 The goal of converting lignocellulosic biomass to hydrocarbon fuels Biomass Conversion Remove xygen Increase the energy density Control MW / formation C-C bonds 1 st Step / Conversion Convert the solid biomass into Gas or Liquid platforms Partial removal of xygen Thermochemical Whole Biomass Deconstruction Hydrolysis Sugar monomers/ Upgradable intermediates 2 nd Step / Upgrading Catalytic Upgrading to final Biofuel Removal of the remaining xygen C-C coupling controlled reactions Final BIFUEL

7 Hydrolysis Routes Pathways to convert sugars and polyols to biofuel through production of monofunctional intermediates 1,2 1 E. L. Kunkes, D. A. Simonetti, R. M. West, J. C. Serrano-Ruiz, C. A. Gartner and J. A. Dumesic, Science, 2008, 322, David Martin Alonso, Jesse Q. Bond and James A. Dumesic Green Chem., 2010, 12,

8 Hydrolysis Routes Hydrolysis Route through Sugar/Polyols Monomers Reaction pathways to upgrade HMF by aldol-condensation to liquid alkanes G.W. Huber, J.N. Chheda, C. J. Barrett and J. A.Dumesic, Science, 2005, 308,

9 Processes for Liquid Biofuels Most Important Technologies of thermo-chemical conversion for Liquid Biofuel production Gasification Production C/H 2 F-T Conversion Into linear CxHy Finishing - Isomerization BIFUEL Pyrolysis Slow Pyrolysis Fast Pyrolysis Char Production Bio-oil Production Bio-oil Hydrotreatment BIFUEL Hydrothermal Liquefaction Bio-oil Production In the presence of water Bio-oil Hydrotreatment BIFUEL

10 Thermochemical Processes Thermochemical Conversion of Biomass R.W. Nachenius, F. Ronsse, R.H. Venderbosch, W. Prins Advances in Chemical Engineering, Vol. 42, Burlington: Academic Press, 2013, pp

11 Composition of Bio-ils Composition of Pyrolysis Bio-ils The exact composition depends on the Biomass Soure and Process Conditions They contain : Acids, Alcohols, Ketons, Aldehydes, Phenol A Typical Composition of a Bio-il : Pyrolitic lignin and suspended solids : 22-36% ph : Water : 20-28% Density : g/cm 3 Hydroxyacetaldehyde : 8-12% xygen : % Levoglucosan : 3-8 % LHV : MJ/Kg Acetic Acid : 4-8% Cetane N. : 10 Formic acid : 3-6% Formaldehyde : 3-4% Acetone : 3-6% Cellobiosan : 1-2% Glyoxal : 1-2%

12 Monolignols The most common types of molecules in Bio-oils from Lignin derive from the building blocs of Lignin ( Monolignols )

13 Linkages in Lignin derived molecules The most common types of linkages in bio-oils from Lignin 1) Aryl ether β--4 linkage between one aromatic ring and an oxygen atom that is bounded to a carbon atom of an alkyl substitute of another aromatic ring 2) Phenylcoumaran β-5 linkage between one aromatic ring and the carbon atom of the coumaran ring. CH 3 H H CH 3 H β--4 linkage β - 5 linkage

14 Linkages in Lignin derived molecules 3) Biphenyl 5-5 linkage between two different aromatic rings 4) Pinoresinol β-β linkage between two tetrahydrofurans which are bonded together but also to an aromatic ring each HC CH 3 H 3 C H H H H 3 C CH 5-5 linkage H β-β linkage CH 3

15 Linkages in Lignin derived molecules 5) Dibenzodioxocin linkage between two aromatic rings but also between an aromatic ring and a carbon atom of a methoxy group attached to another ring. CH CH H CH 3 CH 3 H 3 C CH 2 H linkage

16 Pyrolysis Gas Composition Typical Gas Composition at various pyrolysis temperatures Wang X., Kersten SRA., Prins W., van Swaaij WPM. Ind. Eng. Chem. Res., 2005, 44(23),

17 Characteristics of Bio-ils Properties of the Pyrolysis Bio-ils After Fast Pyrolysis the bio-oil shows some intrinsic disadvantages for its use as a neat biofuel or in blends with other petroleum fractions These drawbacks are strongly related to the Pyrolitic Lignin molecules and the functional groups of the existing compounds Basic Characteristics : Bio-oil tends to polymerize during long storage periods It has poor heating value It has poor thermal stability It is non-volatile It has high viscosity It is highly corrosive due to the presence of carboxylic acids It is immiscible with fossil fuels (diesel)

18 Alternative pretreatments Bio-il Pretreatment Aging is accelerated with temparature because polymerization reactions are promoted For the effective HDT and storage of the Bio-oils stabilization is attempted Catalytic treatment during pyrolysis Catalytic Post-treatment after Pyrolysis Advantages Disadvantages ne step Process The catalyst operates NLY at Pyrolysis conditions The catalyst can operate at Different conditions Another reactor is needed After Pyrolysis The composition and the properties of the final Bio-il Depend on the biomass feed material, the pyrolysis conditions and the stabilization treatment

19 Hydrotreater simulation Hydrotreatment of Bio-ils Efficient Design and peration of Hydrotreaters A good knowledge of the chemical composition of Bio-oils Raw material, catalyst and reaction conditions of pyrolysis stabilization Processes Before Hydrotreatment the pre-treatment process must be controlled What are the compounds (group) or the functional groups/structures that control aging and instability? How can we eliminate them or their action? How can we minimize the xygen amount in the final Bio-il?

20 Hydrotreating Alternatives in Hydrotreating Mild Hydrotreatment Stabilization Production of oxygenated compounds Chemicals Fuels HDT Hydrodeoxygenation - Remove xygen - Hydrogenate Aromatics HDT Hydrocracking - Reduce molecular size Co-Process with Petroleum Fractions Bio-Fuels

21 HTD - HC Typical Flow Diagram of Bio-il Hydrotreatment Elliott D. C. WIREs Energy Environ doi: /wene.74

22 HDT-Feed and Product Composition Composition of Feeds and hydrotreated products ( 1, 2 and 3) Component group Feed 1 (%) 1 (%) Feed 2 (%) 2 (%) 3 (%) Unsaturated ketones/aldehydes Carbonyls (hydroxyketones, aldehydes) Total alkanes Saturated guaiacols (diol,ones) Phenol and alkyl phenols Alcohols and diols HD aromatics Total saturated ketones Total acids and esters Total furans and furanones Total tetrahydrofurans Complex guaiacols Guaiacol and alkyl guaiacols Unknowns Total Douglas C. Elliott *, Todd R. Hart, Gary G. Neuenschwander, Leslie J. Rotness, Alan H. Zache Environmental Progress & Sustainable Energy, 2009, 28(3)

23 And otred HC Feed and Product Composition Composition of Feed1 products ( 1, 2, 3 and 4) after hydrocracking Component groups 1 (%) 2 (%) 3 (%) 4 (%) Feed 1 (%) Unsaturated ketones Carbonyls (hydroxyketones) Naphthenes Saturated guaiacols (diol,ones) Phenol and alkyl phenols Alcohols and diols HD aromatics Total saturated ketones Total acids and esters Total furans and furanones Total tetrahydrofurans Complex guaiacols Guaiacols/syringols Straightchain/branched alkanes Unknowns Total

24 Co-Processing Co-Processing Strategy : Mild hydrotreating (where moderate levels of deoxygenation take place) coupled with co-processing in a petroleum refinery Blending strategies for bio-oil in the petroleum refinery Dist Col Richard J. French, Jim Stunkel, and Robert M. Baldwin Energy Fuels 2011, 25,

25 Current Research Current Process development Efforts focus on Catalytic Hydroprocessing FEEDS - Studies with Model Compounds More fundamental Chemistry questions - Studies with real Bio ils Estimation of process characteristics Scaleup Data Feasibility - Sustainability CATALYSTS - Traditional sulphided Catalysts - Non- traditional precious metal catalysts Much, but not all, of the required hydrogen can be produced from reforming of the gas by-products

26 Model Compounds As real feeds are difficult to handle, model compounds representing the bio-oils most common or refractory molecules are examined. MDEL CMPUNDS Aliphatic H/C Aromatic H/C Carboxylic acids Low MW aldehydes Benzaldehydes Benzoketones Low MW ketones Phenols (substituted or not) Primary Concern : Activity, Selectivity, Reaction Mechanism HD of Functional Groups with Low MW molecules

27 Studies Model Compounds Dexygenation Step Catalyst Selectivity Phenolic C bond Is the most difficult to rupture Direct hydrogenolysis should be avoided - Aromatics Hydrogenation route produces saturated HC Weiyan Wang, Yunquan Tang, Hean Luo, Wenying Liu Reac Kinet Mech Cat, 2010, 101,

28 Model Compound Guaiasol General reaction scheme for GUA conversion with transition metal sulfide catalysts DME, demethylation; DM, demethoxylation; GUA, guaiacol; CAT, catechol; PHE, phenol; Me-CAT, methyl-catechol; Me-PHE, methyl-phenol. V. N. Bui, D. Laurenti, P. Afanasiev, C. Geantet Applied Catalysis B: Environmental, 2011, 101,

29 Model Compound Benzofuran Tentative mechanism for HD of Benzofuran (BF) BF M.C. Edelman, M.K. Maholland, R.M. Baldwin, S.W. Cowley, J. Catal. 111 (1988) 243.

30 Model Compound : Furfural Selectivity of products from Furan Decarbonylation and ring opening (R) (BAL+BL+Butane) reactions Possible reaction pathways for furfural conversion over Cu, Pd and Ni catalysts Catalysts : 1% Pd/Si 4 5% Ni/Si 4 Furfural (FAL) N. Joshin, A. Lawal Chemical Engineering Science, 2012, 84,

31 HDT Reactions 1 Most Common Reactions during Hydrotreatment DEMETHYLATIN REACTIN CH 3 +H 2 + CH 4 METHYLATIN REACTIN H H + CH 3 - Me DEHYDRXYLATIN REACTIN CH 3 CH 3 H H + H 2

32 HDT Reactions 2 HYDRGENLYSIS REACTIN + H 2 H CH 3 + H 2 + CH 3 -CH 3 DEMETHXYLATIN REACTIN H H CH 3 + CH 4 + H 2 H + H 2 H + CH 3 H

33 HTD Reactions 3 DECARBNYLATIN REACTIN H + H 2 + C ARMATIC RING PENING REACTIN + H 2 H KET-ENL TAUTMERISM REACTIN H

34 HDT Reactions 4 CNDENSATIN REACTIN H H + CH 3 CH 3 + CH 3 H CH 3 HYDRGENATIN REACTIN + H 2

35 HDT Catalysts CATALYTIC MATERIALS TESTED SUPPRTS Si 2 γ-al 2 3 ZSM-5(mesoporous/microporous) HBEA C HZSM-5 Zr 2 Ce 2 -Zr 2 Si 2 -Zr 2 -La 2 3 Amorphous borohydrites. ACTIVE METALS Monometallic Fe Cu Pd Ni Ga Pt Rh Bimetallic CoMo NiMo RhPt RhPd PtPd NiCu

36 HDT Experiments Model Compounds Furfural Phenol Benzaldehyde Acetophenone Guaiacol o-m-p-cresol Dibenzofuran Anisole Cyclohexanone Cyclohexanol Experimental Conditions Reactor Type - Batch - Tubural - Continous LHSV : h -1 Reaction Time : 1 20 h Pressure : MPa Temperature : C Catalyst amount used: mg

37 Conclusions Most of the research on Bio-ils concerns the HDT of model compounds with one or more -containing functional groups The most difficult to D compounds are Phenols Catalysts with various selectivities have been tested and a spectrum of different molecules are produced from the various functional groups The design of the Bio-oil hydrotreaters and the strategy to reach the final biofuel strongly depend on Pyrolysis conditions and Biomass type The viable operation of an industrial process for biofuels production from biomass is strictly related to prediction of the performance of the Pyrolysis Pretreatment system using various lignocellulosic raw materials Stabilization of the Bio-ils after Pyrolysis is crucial for storage and further hydro-processing Co-feeding Bio-ils and petroleum fractions is a promising way to reach the target of viably and sustainably produce biofuels from lignocellulosic mass in the short term