Biomasses for energy production Fred Meunier CenTACat, Queen’s University Belfast, UK

1. Biomasses for energy productionFred MeunierCenTACat, Queen’s University Belfast, UK Summer School in Energy and Environmental Catalysis University of Limerick, July 2005

2. 1. Gasification of bio-masses • 2. Fast pyrolysis of bio-masses • 3. “Bio-electricity” project • Steam Reforming of bio-oil for H2 production • 4. Steam reforming of model compounds / PGM • 5. Bio-oil steam reforming on powdered catalysts • and on monoliths Outline

3. 1. Biomass as Gasification Fuel Biomass: natural substance, storing solar energy as chemical energy by photosynthesis. Renewable and CO2-neutral Biomass chiefly contains cellulose, hemi-cellulose and lignin (av. composition C1H1.6O0.8) Examples: wood, crop residues, animal wastes, sewage, and waste from food processing. Total combustion: 1 kg biomass + 6 kg air  CO2 + H2O + ashes Gasification: 1 kg biomass + 1.5 kg air  CO + H2 + CO2 + tar + PM Most biomasses with moisture content of 5-30% can be gasified.

4. Gasification of biomass: where and why? Technology for providing affordable and competitive electricity supply and energy services to rural areas where agricultural and plantations wastes are available. Traditional ways of burning biomass: low efficiency, toxic emissions Typical gasification reactor: receives air and solid fuel and converts them into gas, followed by a cooling and washing train where the impurities can be removed. Final use of gas: Work: cleaned combustible gas used in diesel-generator sets in dual fuel mode Heat: producer gas-based engine generator (little or no purification needed) flame T up to 1200 C.

5. Performance of gasifier-engine system Efficiency in the production of producer gas: up to 70% at best. Efficiency of diesel and gasoline engines: 30% and 20% respectively. In practice, a power drop ranging from 25 % to 60 % can be expected when diesel or gasoline engine is run with producer gas C. Turare , University of Flensburg, Germany

6. Difference between diesel and gasoline engine Diesel + air: auto-ignition Producer gas- air mixture does not auto-ignite, need to be co-injected with diesel fuel.In gasoline engine, producer gas + air can be ignited by the spark. (more convenient in remote rural areas)

7. Gasification Process Gasification: conversion of solid carbon fuels into COx/H2 by a thermochemical process. Accomplished in a sealed chamber at ambient pressure. C. Turare , University of Flensburg, Germany

8. Inside the gasifier Gasification: very complex thermochemical process. Typical gasification stages occur at the same time in different parts of gasifier.  : 2-60 min °C

9. Drying: Biomass fuels consist of moisture ranging from 5 to 35%. At the temperature above 100°C, the water is removed and converted into steam. Pyrolysis: thermal decomposition of biomass fuels in the absence of O2 (not involving O2). Type of products (i.e. solid, liquid or gas) depends on biomass and operating conditions. The heating value of gas produced during the pyrolysis process is low (3- 9 MJ m-3). • Oxidation: Air introduced react in the oxidation zone: T = 700-2000°C • C + O2 = CO2rH(273 K) = - 400 kJ/mol H2 + ½ O2 = H2O rH(273 K) = - 242 kJ/mol

10. In the reduction zone (O2-free), a number of high temperature chemical reactions take place in the absence of O2: • rH(273 K) Boudouard reaction CO2 + C = 2 CO + 172 kJ/molWater-gas reactionC + H2O = CO + H2 + 131 kJ/mol • Water-gas shift reaction CO + H2O = CO2 + H2 - 41 kJ/molMethane production reactionC + 2 H2 = CH4 - 75 kJ/mol • Globally the reduction zone is endothermic (T decrease). • Some ash and char (unburned carbon) remain. • Various CO, CO2, H2 mixtures can be produced:

11. Gas produced by gasification "Producer-Gas“: made from coal and distributed in most cities until natural gas (methane) came in after 1930. Consists primarily of CO, H2, CH4, and N2: 20 % CO + 20 % H2 + 3 % CH4 + 12 % CO2 balance N2. The calorific value is about 5 MJ/kg "Wood-Gas“: similar gas made by partial oxidation of biomass (usually in a downdraft gasifier) and containing typically 50% N2, 8% CO2, 22% CO, 18% H2 and 2% CH4. Produced by wood gasifiers during WW II. (Also can contain up to 2,000 ppm tar) Note: "Synthesis gas“: specific name for a gas composed largely of H2 and CO (no N2) Used to make methanol (CO + 2 H2 over Cu-Zn catalyst); ammonia (shift CO to H2 and use iron catalyst); and many hydrocarbons (Fischer-Tropsch synthesis). "Biogas“: gas produced by the fermentation of organic materials in big wet tanks. It typically contains 60% CH4 and 40% CO2. Similar gas comes from landfills.

12. Suitability of some biomass fuels The quality of producer gas depends upon the several factors including type of fuel. Charcoal: product of wood carbonisation (no air). 5 tonnes of firewood  1 tonne of charcoal (costly) Has twice the heating power of wood, but more than 50% of energy is lost! Unlike firewood, it burns slowly and does not produce any smoke. Low tar content, hence appropriate for all kinds of gasifiers. Low mineral matter content. Compared to other biomass fuels, charcoal is costly.

13. Wood The main combustible components are cellulose and lignine (composition C1H1.6O0.8). Other minor combustible components in wood are resins and waxes. The major non-combustible component of wood is water which is present up to 50 % in freshly cut wood. Low ash content (less than 1 %) Because of high oxygen content, the calorific value is low (16-20 MJ/kg). Next to charcoal, wood is quite suitable fuel for fixed bed gasifiers. As wood contains high volatile matter, updraft gasifier system produce a gas containing tars, which need to be cleaned before using in engines. Downdraft reactors can be designed to produce relatively tar-free gas. After passing the gas through simpel clean-train, it can be used in the internal combustion engines.

14. Sawdust Unpellatized sawdust lead to the problems of excessive tar production, inadmissable pressure drop and lack of bunker flow. Such problems can be minimized by use of densified (pelletized) sawdust. Small sawdust particles can be used in fluidized gas producers to produce burning gas. If this gas is used to be in internal combustion engines, a clean-up system is essential. Peat Peat: first stage of coal formation. Freshly mined peat contains 90 % moisture and 10 % of solid. It cannot be utilised unless air dried to reduce moisture content to 30 % or less. Its heating value (around 20 MJ/kg) is slightly greater than wood. High level of ash. Agricultural residues: biomass materials that are agricultural by-product. (cotton stalks, wheat and rice straw, coconut shells, maize and jowar cobs jute sticks, rice husks) Many developing countries have a wide variety of agricultural residues in ample quantities. Coconut shells and maize cobs have been successfully tested for fixed bed gasifiers and they unlikely creates any problems. Most cereal straws contains ash content above 10% and present slagging problem in downdraft gasifier. Rice husk with ash contents above 20% is difficult to gasify.

15. 1. Gasification of bio-masses • 2. Fast pyrolysis of bio-masses • 3. “Bio-electricity” project • Steam Reforming of Bio-oil for H2 production • 4. Steam reforming of model compounds / PGM • 5. Bio-oil steam reforming on powdered catalysts • and on monoliths Outline

16. 2. Bio-oil production by fast pyrolysis of biomass (biomass liquefaction) Pyrolysis ca. 1 s 550°C no O2 Condensation Bio-oil Liquids + Gases (H2, CO, CH4, C2H2, C2H4) Vapours + Char Biomass Bio-oil: - quenched intermediates of flash degradation of (hemi)cellulose, lignin. - complex mixture of oxygenated hydrocarbons, water, solid char - over 100s different chemicals: acetic acid, formaldehyde complex high molecular weight phenols anhydrosugars and other oligosaccharides

17. fast pyrolysis of biomass Radlein D, “The Production of Chemicals from Fast Pyrolysis Bio-oils”, in Bridgwater A et al. Fast Pyrolysis of Biomass: A Handbook, pp. 165, CPL Press 1999

18. Pyrolysis Principles No O2. First step in combustion and gasification processes. Typical product yields (dry wood basis) obtained thermal processing of wood Fast pyrolysis for liquids production is of particular interest as the liquids are easily transportable and stored.

19. Fast pyrolysis occurs in a time of few seconds or less: • - Heat and mass transfer processes, phase transition phenomena matters • - Limit the low T period! • use small particles (fluidised bed) processes • heat very fast only to the particle surface that contacts the heat source (ablative processes). • rapid cooling of the pyrolysis vapours to give the bio-oil product. • beside wood: straw, olive pits and nut shells to energy crops such as miscanthus and sorghum, forestry wastes such as bark and solid wastes such as sewage sludge and leather wastes.

20. Bio-oil typical properties • The liquid contains many reactive species • “micro-emulsion”: • - stable single phase mixture, with ca. 20 to 30 wt.% water • - continuous phase: aqueous • - discontinuous phase: pyrolytic lignin macro-molecules • - limited solubility in water • - does not mix with any hydrocarbon liquids • - miscible with polar solvents such as methanol, acetone

21. Typical composition of wood-derived bio-oil Moisture content 20-30% pH 2.5 Specific gravity 1.20 Elemental analysis (wt.%) C 55-58% H 5.5-7.0% O 35-40% N 0-0.2% Ash 0-0.2% HHV as produced 16-19 MJ/kg (61 vol.% fossil oil) Viscosity (40C and 25% water) 40-100 cp Solids (char) 0.1 – 0.5% Vacuum distillation residue  up to 50% Reference: http://www.pyne.co.uk/

22. 1. Gasification of bio-masses • 2. Fast pyrolysis of bio-masses • 3.- “Bio-electricity” project • Steam Reforming of Bio-oil for H2 production • 4. Steam reforming of model compounds / PGM • 5. Bio-oil steam reforming on powdered catalysts • and on monoliths Outline

23. Green and sustainable electricity from biomass via fast pyrolysis oil and hydrogen utilising fuel cells 3. “Bio-electricity” project H2 Electricity + HEAT

24. Electricity from biomass/ fast pyrolysis oil/ H2 Why fast pyrolysis oil ? Contains large fraction of energy of raw biomass Can be produced from waste biomasses (e.g., forestry residues, straw) Liquid  easily transportable  good for Distributed Power Generation [DPG] Why H2 ? Produces no pollutants Is essential for Fuel Cell operation Selling price: from biomass, via bio-oil : 6.0-9.5 $/GJ from fossil fuels : 7.8 $/GJ Why fuel cells ? High efficiency Small scale (can be used in DPG mode) Combined heat and power generation Reliability

25. Production of renewable H2 and electricity Biomass Fast pyrolysis Bio-oil Catalytic Steam Reforming H2/CO2/CO Fuel processor Water-gas-shift CO + H2O  H2 + CO2 H2/CO2 MCFC / post combustion Electricity/heat

26. Ansaldo Ricerche S.p.A. The Bio-Electricity consortiumEU project ENK5-CT-2002-00634 5. Steam reforming Powder, monolith 1.Bio-oil production 7. Integration & scale up Stationary MCFC 3. Catalyst preparation Powder, foam, monolith 2. Bio-oil characterisation Process parameters 6. Cracking / Steam reforming 4. Laboratory-scale reformer design

27. Steam Reforming: literature background Industrial H2 production from fossil fuelsnatural gas, LPG Catalyst: Ni/(Ca,Mg)Al2O4Steam reforming of model compoundsCH4, CnH2n+2, alcohols, acetic acid, phenol, sugars Catalysts: supported Ni, PGMSteam reforming of bio-chemicalsBio-ethanol, bio-diesel, sunflower oil Catalysts: supported Ni, PGMSteam reforming of fast pyrolysis oilsSoluble fraction of bio-oil from poplar wood, pine sawdust Catalysts investigated: supported Ni Czernik et al Energy & Fuels, 1999 Czernik et al  full bio-oil, PGM

28. Scope of this work:Steam reforming over PGM-based samples of model compounds and a bio-oil • Catalysts investigated: • 1% Pt/Al2O3 – 1% Pd/Al2O3 – 1% Rh/Al2O3 • 1% Pt/CeZrO2 – 1% Pd/CeZrO2 – 1% Rh/CeZrO2 • Model compounds: • acetic acid, acetone, ethanol, phenol • Bio-oil obtained from fast pyrolysis of beech wood

29. 1. Gasification of bio-masses • 2. Fast pyrolysis of bio-masses • 3.- “Bio-electricity” project • Steam Reforming of Bio-oil for H2 production • 4. Steam reforming of model compounds / PGM • 5. Bio-oil steam reforming on powdered catalysts • and on monoliths Outline

30. 4. Steam Reforming of model compounds • CnHmOk+ H2O ↔ CO / CO2 + H2 • Water-gas-shift: • CO + H2O ↔ CO2 + H2 • Boudouard reaction • 2 CO ↔ CO2 + C • Thermal decompositions • CnHmOk ↔ gases (H2, H2O, COx, CxHy…) + CxHyOz + coke Other reactions taking place:

31. Experimental setup N2 H2 CO CO2 CH4 O2 N2 Model compound + water Pre-Heater Syringe pump Thermocouple (in the catalyst bed) Electrical Furnace Catalytic Reactor Tubular PFR Catalyst bed Gas Chromatograph Cold Trap (0 °C)

32. Typical Chromatograms N2 H2 TCD O2 CO2 Methanator + FID CH4 CO

33. Data analysis: product yields For H2 includes H derived from H2O For CO, CO2 and CH4 Balance to 100% = reactant +coke + CxHyOz + C2+

34. SR of model compounds: acetic acid CH3COOH + 2 H2O ↔ 2 CO2 + 4 H2 100 mg catalyst + 900 mg cordierite Gas flowrates /sccm: AA = 1.80 , H2O = 3.60, N2 = 90.7 water/acetic acid = 2.0 GHSV = 860 h-1

35. SR of model compounds: acetone CH3COCH3 + 5 H2O → 3 CO2 + 8 H2 100 mg catalyst + 900 mg cordierite Gas flow rates/sccm : acetone = 1.79, H2O = 8.99, N2 = 86.6 water/acetone = 5.0 GHSV = 860 h-1

36. SR of model compounds: ethanol CH3CH2OH + 3 H2O → 2 CO2 + 6 H2 100 mg catalyst + 900 mg cordierite Gas flow rates/ sccm: ethanol = 1.84, H2O = 5.52, N2 = 86.6 water/ethanol = 3.0 GHSV = 880 h-1

37. SR of model compounds: phenol C6H5OH + 11 H2O → 6 CO2 + 14 H2 100 mg catalyst + 900 mg cordierite Gas flowrates/ sccm: ethanol = 0.089 cm3 min-1, H2O = 8.91 , N2 = 86.6 water/phenol = 100 GHSV = 43 h-1

38. H2 yield (%) on PGM-based catalysts - - <20 20 < - <40 40 < 0 <60 60< + <80 80 < + + Steam Reforming of model compounds  Rh/ Al2O3 Pt or Rh/ Ce-ZrO2

39. Steam reforming reaction mechanism /Pt ? Reductant Oxidiser v v v v Increased activity with redox oxides CxHyOz CO2 H2O H2 CO CO CO H H Pt H O Pt Metal Oxide CeO v = oxygen vacancy Reductant Acetic acid CH4 H2 Oxidiser H2O CO2 CO2 Steam-reforming: Seshan et al., J. Catal., 2004 CO2-reforming: Ross et al., Stud. Surf. Sci. Catal., 1998 RWGS: Meunier et al., J Phys. Chem. B., 2004

40. 1. Gasification of bio-masses • 2. Fast pyrolysis of bio-masses • 3.- “Bio-electricity” project • Steam Reforming of Bio-oil for H2 production • 4. Steam reforming of model compounds / PGM • 5. Bio-oil steam reforming on powdered catalysts • and on monoliths Outline

41. 4. Steam reforming of bio-oil (beech wood pyrolysis oil from UT /BTG) Bio-oil: only partly soluble in water

42. ENEA (Prof Zimbardi): biomass and bio-oil chartacterisation Biomass: Beech wood 3.3 – 0.8 mm Bio-oil (pH = 3.3) Cl: 0.025% S: 0.085% K: 43 ppm Mg: 44 ppm Ca: 102 ppm

43. Steam reforming of bio-oil CH1.32O0.54+ 1.46 H2O ↔ CO2 + 2.12 H2 Feeding bio-oil is difficult! - Only partly soluble in water  cannot co-feed bio-oil & water in single syringe - Reactant = complex mixture, reactive > 80°C

44. Setup for bio-oil experiments thermocouple Injection needle for water (1/16”) Injection needle for the bio-oil N2 < 80 °C Cooling water (5°C) 10-40 mm Catalyst bed Quartz wool > 800 °C Furnace Gas Chromatograph Condenser

45. Experimental Parameters = 10.8 (stoich. 1.46)

46. : it works! 200 mg + 1000 mg cordierite; T = 860°C ± 30°C liquid flowrate: bio-oil = 14 μL min-1; H2O = 96 μL min-1 N2 flowrate  = 50 sccm GeHSV = 3090 h-1 Bio-oil Steam Reforming Best: Pt and Rh / Ce-ZrO2 Up to 70 % (80 %) H2 yield 1% Rh/Al2O3 1% Pt/Al2O3 1% Rh/CeZrO2 1% Pt/CeZrO2

47. 200 mg + 1000 mg cordierite liquid flowrate: bio-oil = 14 μL min-1; H2O = 97 μL min-1, N2 flowrate = 50 sccm GeHSV= 3090 h-1 1% Pt/Ce-ZrO2: Effect of the temperature > 9 h T > 800 °C 740 °C 795 °C 860 °C

48. 200 mg + 1000 mg cordierite; T = 830 ± 30 °C liquid flow rate, bio-oil = 14.0 μL min-1; H2O = 96.8 μL min-1 Gas flowrate / sccm : N2 = 50, O2 = 0.0 / 1.0 / 2.5 / 5.0 sccm O/C = 0.54 / 0.69 / 0.92 / 1.31 GeHSV = 3090 h-1 O2 addition: bio-oil ATR over 1% Pt/Ce-ZrO2 No benefits with O2 (here) Deactivation ? 0.54 O/C 0.69 0.92 1.31

49. Summary:Bio-oil steam reforming over powdered catalyst • Full bio-oil can be steam reformed (> 9 h) • T ≥ 800°C required to achieve a H2 yield > 70 % • A detrimental effect of O2 was observed • (Ce,Zr)O2 better than Al2O3 as a support

50. Steam reforming over monolitic catalysts 2%Pt/CeZrO2 catalyst 5 x 1cm; m = 3.18g Liquid flow rate: bio-oil = 14.0 μL.min-1, water = 36.2 μL.min-1 N2 flowrate: = 50 sccm GeHSV = 660 > 50 h