Different Aspects of Biomass Pyrolysis: A General Review

Ersan Pütün

Anadolu University, Department of Materials Science and Engineering, Eskisehir, Turkey

eputun@anadolu.edu.t

Energy needs and demands Biomass Biomass potential of the World and Turkey Thermochemical Conversions Pyrolysis Carbonaceous products obtained from pyrolysis and their characterization methods Bio-oil Bio-char

A research example Environmental, Economical and Future Aspects of Biomass

Pyrolysis

Outline

3E Energy Economy Ecology

Meeting the global energy challenge…. Sufficient Available Secure Reliable Sustainable Fossil Fuels ↔ Biomass

Energy?

• The term biomass is ascribed to biological materials derived from living, or recently living organisms.

• The chemical composition of biomass is complex and very different from that of fossil fuels.

Biomass

Agricultural crops& residues

Industrial residues

Forestry crops& residues

Animal residues

Municipal solid waste Energy crops

Currently biomass provides approximately 13% of world primary energy supply and more than 75% of global renewable energy.

Indeed it is estimated that bio-energy could contribute 25–33% of global energy supply by 2050.

World production of biomass is estimated at 146 billion metric tons a

year, mostly wild plant growth. .

5 http://www.eia.doe.gov/

Biomass Potential of the World

http://www.eia.doe.gov/

Agricultural Biomass Potential of Turkey

Total available waste amount= 16 MT (303,2 PJ total heating value)

Foresty Biomass Potential of Turkey… Total forestry waste= 48 MT (1,5 MTEP)

Biomass Potential of Turkey

http://www.eia.doe.gov/

Biomass can be considered as a natural composite material which is mainly consisted of cellulose, hemicellulose, and lignin.

Minor amounts of minerals and lower molecular weight organic materials (solvent extractives) are also included in the biomass structure

Lignocellulosic Material

Cellulose (40-50 %)

Glucose monomer

Hemicellulose (25-35 %)

Xylose monomer

Lignin (16-33 %)

Phenyl propanoid monomer units

Water (3-10 %)

Organic extractives Inorganics

(K, Na, Ca, Mg, P…etc.)

Different thermal degradation reactions:

• T> 200° C water is lost • T> 250° C several competing pyrolytic reactions

grouped into three basic classifications:

o At lower temperatures → water, CO, CO2 and a carbonaceous char

o At higher temperatures → depolymerization of the cellulose chain → anhydroglucose derivatives, volatile organic materials and tars.

o At still higher temperatures →bond cleavage of cellulose → low molecular weight compounds.

Thermal Degradation of Cellulose

• Hemicellulose decomposes → 200-260 °C → more volatiles, less tars, and less chars than cellulose.

• Hemicellulose is lost in slow pyrolysis of wood → 130-194 °C, with most of this loss occurring above 180 °C.

Thermal Degradation of Hemicellulose

Thermal Degradation of Lignin

• Lignin decomposes → 280-500 °C. • Lignin pyrolysis → more residual char • DTA studies → a broad exotherm

plateau → from 290 °C to 389 °C → followed by a second exotherm, peaking at 420 °C →tailing out to beyond 500 °C.

• Lignin decomposition in wood → begins at 280 °C → continues to 450-500 °C → with a maximum rate at 350-450 °C.

Thermochemical Conversions

Biomass

Combustion

Hot gases

Gasification

Pyrolysis

Liquifaction/ Hydro thermal upgrading

Low-energy gas

Medium-energy gas

Char

Hydrocarbons

Fuel-oil and

distillates

Fuel gases

Methane

Syn Liquids Methanol Gasoline

Internal Combustion

Engines

Steam Process

Heat Electricity

Thermochemical Process

Intermediate Process

Final Product

Main processes, intermediate energy carriers and final energy products from the thermo-chemical conversion of biomass

Pyrolysis • …….the thermo-chemical decomposition of organic materials by heating in the absence of

oxygen.

• It commonly refers to lower temperature thermal processes producing liquids as the primary product.

C containing feedstock

Pyrolysis

C rich char

Volatiles

Liquid products

Gaseous products

Operating conditions Temperature Heating rate Pressure Catalyst presence Sweeping gas Vapor residence time Reactor type (Retorts, Kilns, Screw Reactors,

Rotary drum reactors, Moving bed reactors, Microwave reactors, Fluidised bed reactors…

Feedstock characteristics Particle size Biological constituent content (cellulose,

hemicelloluse, lignin & extractives) Moisture content Ash content Mineral content Morphology

Factors Effecting Biomass Pyrolysis….

Bio-char • can be used as solid fuel in boilers • can be used futher for the gasification process to obtain

hydrogen rich gas by thermal cracking, • could be used directly as activated carbons or for the

production of activated carbon via applying different methods,

• useful as a sorbent for air pollution control as well as for wastewater treatment.

• serve as catalysts and catalyst supports

• used as combustion fuel, • used for power generation, • can be used for production of chemicals and resins, • can be used as a transportation fuel and could be a good

substitute for fossil fuels, • suitable blend with diesel oil may be used as diesel engine

fuels, • easily stored and transported, and hence need not to be used

at the production site.

Bio-oil

• Complete chemical characterization of bio-oil is difficult and many instrumental and analytical techniques are used for characterization:

o GC, GC-MS→volatile compounds o HPLC, HPLC-electrospray MS→nonvolatile compounds o NMR→nuclear magnetic resonance → types of hydrogens or carbons in

specific structural groups, bonds, area integrations o FT-IR→ Fourier transform infrared spectroscopy → functional groups o GPS→Gel Permentation Spectroscopy → molecular weight distributions

Chemical characterization of bio-oil

Chemical characterization of char

o Solid state NMR→nuclear magnetic resonance → types of carbons in specific structural groups

o FT-IR→ Fourier transform infrared spectroscopy → functional groups o SEM → Scanning Electronic Microscopy → surface morphology o EDX → Energy-dispersive X-ray Spectroscopy → surface chemicals o XRD → X-Ray Diffraction → crystallographic structure o Gas adsorption → Surface area determination

Pyrolysis

Oil shale & Coal Plastics Biomass

Liquid

Solid

Heavy Metals

Toxic Dyes

Phenolic Compounds

Adsorption

Activated Carbon

Gas

Chemical Activation

Physical Activation

Pesticides Petroleum Hydrocarbons

GC

TG-FTIR

TG-MS

Carbon Materials

Carbonaseous Material Decomposition

Activated Carbon

Carbon Foam

C-Fiber

Pathway of our studies

A research example carried on pyrolysis….

Project Title; Investigation of pyrolysis kinetics of coal,biomass and plastic blends by thermogravimetry and characterization of the products (Supported by Anadolu University Scientific Research Council, Project No: 1001F68)

Purpose; Identification of pyrolytic and co-pyrolytic behaviours of different biomass samples with coal and plastics

Waste PET bottles Lignite

Corn stalk and cotton stalk were agricultural wastes. Hazelnut shells were industrial wastes of food processing. Enormous production of hazelnut, cotton and corn in Turkey leads to availibility of bio-wastes…. Hazelnut production 1st country Cotton production 8th country Corn production 21st country throughout the world

Raw materials and their selection

Polyethylene terephthalate (PET) is one of the most commonly used polymers. In 2011 7.5 million tons and 1.6 million tons of PET were collected in worldwide and Europe, respectively.

Biomass Samples

Turkey has approximately 2% of the world's lignite reserves. However, Turkish lignites have low calorific value and contain relatively higher amounts of ash and sulphur.

Experimental Procedure

RAW MATERIALS

Air dried, ground, screen analysis, proximate, ultimate and compositional analysis

Preperation of blends (with a ratio of 1/1 wt./wt.)

Bio-oil Bio-Char

CHARACTERIZATION

Elemental Analysis

FT-IR

BET surface area

SEM-EDX

PYROLYSIS

Elemental Analysis

FT-IR 1H-NMR

GC-MS

In fixed bed reactor In combined TGA/FT-IR/MS system

Kinetic Studies

Evolved Gas Analysis (EGA)

Results (Product Yields)

Heating rate= 10 oC/min Pyrolysis temperature= 550 oC Nitrogen flow rate= 100 cm3/min

Higher tar yield Highest char yield

Results (Product Yields, cont’d)

PET caused synergetic effect on co-pyrolysis of biomass by increasing liquid product yields. Lignite addition of biomass decreased liquid product yield and increased char yield due to high ash content.

Heating rate= 10 oC/min Pyrolysis temperature= 550 oC Nitrogen flow rate= 100 cm3/min

Results (Elementel Analysis & Heating Values)

wt. % Cotton stalk Corn stalk Hazelnut shells PET Lignite C 40,28 35,95 48,36 61,34 56,25 H 5,95 5,42 6,22 4,28 4,96 N 1,46 1,49 0,50 0,00 1,58 S 0,29 0,12 0,00 0,00 0,37 O 52,02 57,02 44,92 34,38 36,84

H/C 1,760 1,796 1,533 0,831 1,051

O/C 0,967 1,191 0,697 0,421 0,492

High heating value (HHV) (MJ/kg)

12,856 9,709 17,233 20,726 19,576

Raw materials

Highest C content Highest HHV

Cotton stalk

Corn stalk

Hazelnut shells

Lignite Cotton s.

+PET

Corn s.

+PET

Hazelnuts.

+PET

Cotton s. +

Lignite

Corn s.

+Lignite

Hazelnut s.

+ Lignite

PET

+Lignite C 67,47 66,44 68,04 75,33 59,33 65,84 84,12 68,98 65,57 70,56 60,22 H 7,80 7,39 7,15 7,92 5,29 5,70 7,49 7,59 7,41 6,98 4,53 N 1,32 0,78 0,90 0,46 0,02 0,44 0,26 0,65 0,84 1,01 0,38 S - - - - - - - - - - - O** 23,41 25,39 23,91 16,29 35,36 28,02 8,13 22,78 26,18 21,45 34,87 H/C 1,38 1,33 1,25 1,25 1,06 1,03 1,06 1,31 1,35 1,18 0,90 O/C 0,26 0,29 0,26 0,16 0,45 0,32 0,07 0,25 0,30 0,23 0,44 HHV (MJ/kg)

29,86 28,56 29,02 33,97 21,33 25,45 37,80 30,18 28,15 30,07 20,62

Liquid products

Results (Elementel Analysis & Heating Values)

Highest C content Highest HHV

Cotton

stalk

Corn

stalk

Hazelnut shells

Lignite Cotton s.

+PET

Corn s.

+PET

Hazelnuts.

+PET

C 63,74 57,55 85,43 67,92 67,20 71,20 86,54 H 1,22 1,21 1,61 1,53 1,38 1,48 1,59 N 0,46 0,91 0,014 1,40 0,36 0,81 0,05 S 0,31 0,00 0,00 0,39 0,28 0,00 0,00 O 34,27 40,33 12,946 28,76 30,78 26,51 11,82 H/C 0,228 0,251 0,225 0,268 0,245 0,248 0,219 O/C 0,404 0,526 0,114 0,318 0,344 0,280 0,103 HHV(MJ/kg) 17,171 13,941 28,889 20,034 19,20 21,441 29,439

Chars

Results (Elementel Analysis & Heating Values)

Highest C content Highest HHV

Sample BET Surface Area(m2/g)

Hazelnut shell 10,37

Corn stalk 102,60

Cotton stalk 0,97

Lignite 10,57

Hazelnut Shell +PET 143,28

Hazelnut shell+Lignite 117,37

Corn stalk +PET 294,91

Corn stalk + Lignite 78,36

Cotton stalk +PET 20,29

Cotton stalk + Lignite 43,14

PET-Lignite 61,34

Results (BET Surface Areas of Chars)

In co-pyrolysis, cotton stalk and lignin presence decreased BET surface area values.

On the other hand, co-pyrolysis wit

PET increased BET surface areas.

Results (FT-IR and SEM-EDX Analysis of Chars)

Pyrolysis caused evolvemet of oxygen from the structure of raw materials and cracking of the aromatic structures which leads to carbonaceous solid products.

Morphologies of bio-chars were observed different when PET and lignite were blended with biomass samples.

BET surface area of corn stalk+PET char were foung highest and SEM micrographs showed formation of porous structure due to pyrolysis

SEM micrograph and EDX analysis of Corn stalk + PET sample

Results

As a general conclusion of the project , valuable solid and liquid products can be achieved from co-pyrolysis of biomass

with lignite or PET under proper conditions. By this way, disposal of plastics and evaluation of low-ranked coals by co-

pyrolysis may be a sustainable and an enironmentally-friendly choice.

• Biomass pyrolysis technology offers a great deal of potential for human and environmental gain

• No net CO2 or SOx addition to the atmosphere • Unfortunately, combustion of bio-oil also has its drawbacks. oHigh particulate content

Environmental, Economical and Future Aspects of Biomass Pyrolysis

• In the short term, carbonaceous products from biomass cannot hope to compete with the vast fossil fuel.

• Studies have emerged, however, of smaller niche markets available for biomass

pyrolysis technology. • In the long term, larger scale “biorefineries” which would integrate every step of

processing and refinement will take place and these bio-refineries will be more economical than today’s smaller markets.

• To reinforce the utilization of biomass conversion technologies the states should

reduce the taxes and support manufacturers for production.

Environmental, Economical and Future Aspects of Biomass Pyrolysis (cont’d)

• Biomass provides a promising answer to world energy needs and a potentially viable

alternative to fossil fuels. • The utilization of a significant amount of these biomass resources would also require a

concerted R&D effort for developing technologies to overcome the cost barriers. Demonstration projects and incentives (e.g., tax credits, price supports, and subsidies) would be required.

• Additional efforts would be required to discern the potential impact that large-scale forest and crop residue collection and production of perennial crops could have on traditional markets for agricultural and forest products.

Environmental, Economical and Future Aspects of Biomass Pyrolysis (cont’d)

• Unique among biomass-generated fuels in its variability and limitless feedstock possibilities, bio-oil is the most versatile alternative fuel on the market.

• In order for bio-oil to gain a larger share of this market, a few important issues need to be

addressed.

o Scale-up from smaller models used now o Reduce overhead costs o Set industry-wide product quality standards o Encourage developers and investors o Disseminate information to the public o Address environmental and safety issues in handling and storage

Environmental, Economical and Future Aspects of Biomass Pyrolysis (cont’d)