BIORAFFINERIARAFFINERIA

PETROLCHIMICA BIORAFFINERIA

• PETROLIO

Composizione complessa

Non rinnovabile

Estrazione lunga, laboriosa e costosa

Costo elevato (70-80$/barile, circa 370 €/ton)

Giacimenti limitati in particolari aree del Mondo

• Carburanti, energia, calore, chemicals

• Processi inquinanti

• BIOMASSE (in particolare scarti agro-forestali lignocellulosici).

Composizione complessa

Rinnovabile

Raccolta semplice e veloce

Basso costo (10-150 €/ton)

Disponibile in qualsiasi Paese

• Biocarburanti, energia, calore, chemicals

• Processi non inquinanti e rispettosi dell’ambiente (la CO2 prodotta durante il processo viene rapidamente fissata dalle biomasse)

SCOPO BIORAFFINERIA: Valorizzare in toto la biomassa di partenza

Bioraffineria1. Valutazione della composizione della biomassa

2. Pretrattamento (fisico, chimico o biologico) per separare le diverse componenti della biomassa3. Separazione delle diverse frazioni ottenute dai pretrattamenti4. Utilizzo delle molecole contenute nelle diverse frazioni per la realizzazione dei prodotti5. Separazione, purificazione e formulazione dei prodotti ottenuti

lignocellulose pretreatment to fractionate the recalcitrant lignocellulose structure; enzymatic hydrolysis of the isolated cellulose moiety, by which cellulases hydrolyze reactive intermediates to fermentable sugars; and fermentation, which produces cellulosic ethanol or other bio-based chemicals

SCHEME OF BIOREFINERY PLANT

La parete cellulare ha una struttura molto complessa e altamente organizzata essa è composta da diversi strati concentrici che si depositano durante l’accrescimento della cellula.

Rappresentazione schematica di cellule vegetali e dell’organizzazione della parete cellulare. Lamella mediana (ML), parete primaria (P), strato esterno della parete secondaria (S1), strato intermedio della parete secondaria (S2), strato interno della parete secondaria (S3), membrana plasmatica (W).

STRUTTURA DELLA CELLULA VEGETALE

Glucose polymerization (β-1,4 glycosidic linkages) Chains assembled into sheets

(intramolecular + intermolecular H-bonds)

Sheets stacking (Van der Waals)

Spin of the sheets into highly organized fibrils (crystalline and amorphous

domains)

CELLULOSECELLULOSE

Incredibly strong fibers, resistant to the action of enzymes (cellulases) that can crack them back into their simple-sugar

components Mechanical (mill)/ chemical (ionic liquid) pretreatment required to break cellulose for the

production of fuel alternatives

cellobiose repeating unit

β(1-4) glycosidic linkage

crystallin domain

cell wall

cellulose microfibril

hemicelluloses bounded tothe surface area and

trapped into the microfibril

β(1-4) glucan chains

cellobiose repeating unit

β(1-4) glycosidic linkage

crystallin domain

cell wall

cellulose microfibril

hemicelluloses bounded tothe surface area and

trapped into the microfibril

β(1-4) glucan chains

Aggregazioni della cellulosa in microfibrille

A cellulose chain may be 5-7 μm long, but a fibril can be much longer, probably at least 40 μm due to several chains overlapping each other. Each cellulose microfibril has approximately 36 glucose chains, and every elementary fibrils are further associated into larger units, called fibrils aggregates, by means of non-cellulosic polymers

Shorter, branched chains: 500-3000 sugar units (cellulose: 7000-15000) that cross-link together cellulose fibrils and covalently bind lignin via ester and ether linkages (Lignin-Carbohydrate Complexes, LCC)

Hemicellulose is composed of carbohydrates based on pentose sugars, mainly xylose and arabinose, as well as hexose sugars, such as glucose and mannose. Mannuronic and galacturonic acid are often present

Abundant in crop residues, great potential in the production of chemicals

HEMICELLULOSE (ARABINOXYLANS, XYLANS )HEMICELLULOSE (ARABINOXYLANS, XYLANS )

Tridimensional, racemic, non-crystalline, hydrophobic polymer that embeds together the Tridimensional, racemic, non-crystalline, hydrophobic polymer that embeds together the lignocellulosic components. lignocellulosic components.

Plays a crucial role in providing mechanical support and in the plant natural Plays a crucial role in providing mechanical support and in the plant natural defense against degradation. defense against degradation.

Hardwood:

Softwood:

Herbaceous:

G-OH + S-OH G-OH P-OH + G-OH + S-OH

Sinapyl alcohol (S-OH)

Oxidative coupling of mesomeric phenoxy radicals

Coniferyl alcohol (G-OH)

Paracoumaryl

alcohol (P-OH)

LIGNIN

LIGNINLIGNIN

β-O-4 β-β β-5 5-5’-O-4

LIGNIN-CARBOHYDRATE COMPLEXES LIGNIN-CARBOHYDRATE COMPLEXES (LCCs)(LCCs)

In herbaceous plants, lignin and In herbaceous plants, lignin and hemicellulose are connected through a hemicellulose are connected through a phenolic bridge. Ferulic and p-coumaric phenolic bridge. Ferulic and p-coumaric acids are esterified to hemicelluloses and acids are esterified to hemicelluloses and lignin, respectively. lignin, respectively.

In wood, LCCs mainly consist of ester In wood, LCCs mainly consist of ester and ether linkages connecting sugar and ether linkages connecting sugar hydroxyls of hemicellulose to the hydroxyls of hemicellulose to the --carbanol of phenylpropane subunits in carbanol of phenylpropane subunits in lignin. lignin.

O

OH

OLignin

O

O

O[Xyl Xyl Xyl]

OH

OH

OCH3

OH

OCH3

O

OH

OLignin

O

OH

OCH3

O

[Xyl Xyl Xyl]

CH3CH3

OH

O

OR

OOCH3

Lignin

O

O[Arabinoxylan]

OLignin

OOO

O

CH3CH3

[Xyl Xyl Xyl]

OCH3

Crestini C.; Argyropoulos D.S. Structural Analysis of Wheat Straw Lignin by Quantitative 31P and 2D NMR Spectroscopy. The Occurrence of Ester Bonds and β-O-4 Substructures. J. Agric. Food Chem. 1997, 45, 1212-1219

Lignocellulose biomass pretreatment

The objective of pretreating lignocellulosics is to alter the structure of biomass and to make the cellulose and hemicelluloses more accessibile and ame:nable to hydrolytic enzymes following these criteria:

•minimization of hemicellulose degradation products

•limiting the formation of by-products that inhibit ethanol fermentation

•reducing energy/water use and lowering environmental impacts, capital and operating costs

Lignocellulose biomass pretreatment: Steam Explosion

Steam explosion involves rapidly heating biomass with steam at elevated temperatures (190-240 °C) with residence times of 3-8 minutes followed by explosive decompression. This treatment promotes hemicellulose hydrolysis and opens up the plant cell structure, although enhanced digestibility of cellulose is only weakly correlated with the physical effects

Lignocellulose biomass pretreatment:Acid and base pretreatment

Dilute acid pretreatment has been extensively studied and typically employs 0.4-2% H2SO4 at temperatures of 160–220 °C to remove hemicelluloses and enhance cellulase digestion of cellulose

Aqueous lime or NaOH pretreatment has been shown to be effective for wheat straw and sugarcane bagasse at lower temperatures than acid treatments; however, the treatment times are in some cases on the order of hours (20). The use of an alkaline treatment also incurs additional capital cost, as the recovery of salts requires a lime kiln to regenerate the base.

Lignocellulose biomass pretreatment:Ammonia pretreatment

Ammonia pretreatment involves pretreating biomass with an aqueous ammonia solution causing depolymerization and cleavage of lignin–carbohydrate bonds. Agricultural residues and herbaceous plants treated in this manner exhibit an excellent response to cellulase. However, woody biomass is often not efficiently treated by this technology, and in all cases, ammonia recovery is an additional cost and an important consideration

Organosolv pretreatment of biomass resides on the use of an organic solvent system (23-26) with enhanced lignin solubilizing properties. Usually, the resultant cellulosic fraction is highly susceptible to enzymatic hydrolysis, generating very high yields of glucose that can be readily converted to ethanol

Lignocellulose biomass pretreatment: organosolv pretreatment

Lignocellulose biomass pretreatment:ionic liquid

Once the ionic liquid has dissolved the lignocellulose biomass into its components, the subsequent addition of an anti-solvent, such as water or ethanol, results in the sugars being precipitated out while a fairly large fraction of the lignin remains in solution

t0 20 min 50 min 2 ht0 20 min 50 min 2 h

Il network tridimensionale che lega lignina e polisaccaridi rende molto complicato

dissolvere il materiale nelle sue componenti in solventi tradizionali

LIQUIDO IONICO(sale costituito da grande catione organico e piccolo anione inorganico)

1-allyl-3-metilimidazolo cloruro- [Amim]Cl

Alto bollenteNon tossicoBiodegradabileRiciclabile

Non infiammabileChimicamente stabileAlta conduttività termica

Composto verde

Catione organico: interazione π-π con lignina; Anione inorganico: rottura legami-H inter-intra molecolari della cellulosa

Meccanismi di idrolisi

Doppia possibilità di meccanismo:• “Endo”

• “Eso”

Depolimerizzazione cellulosa; Trattamento CON CELLULASI MECCANISMO

Trattamento cellulolitico: i campioni vengono messi in bagno termostatico per due giorni a 40 °C con tampone acetico e cellulasi, un’enzima secreto dal fungo Trichoderma reseei capace di idrolizzare la cellulosa a glucosio

Meccanismo di azione dell’enzima