The aim of Aaron's project is to research into the pathways of synthesising liquid lignin fuel and terpene-derived biopolymers with assessment and optimisation of their characteristics regarding their suitability for use within automobiles.
Project Summary
The project will concern two products while concerning the concept of the biorefinery:
Lignin – Biofuel
Terpene – polymer
Lignin – Biofuel
Lignin is a complex polymer made up of phenolic units (monolignols) and is sourced from lignocellulosic material (i.e. crop residues, wood, grasses).
Lignin is also a by-product of the Kraft Pulping Process and accounts for 85% of global lignin production. Lignin is burned to provide heating and power to the paper mills. Lignin has good fuel potential and more energy-rich than ethanol.
Lignin is a solid and though work has been done to depolymerise lignin to return a liquid-phase product, the processes require expensive energy intensive methods and results in poor yields (also mostly burns rather than melt).
A potential route to producing a liquid lignin product is to substitute the hydroxyl groups of the phenol units with an alkyl ether (methyl or ethyl). Lignin is amphiphilic due to the hydroxyl group (hydrophilic) and carbon content (hydrophobic). Replacing the hydroxyl groups with an alkyl ether would break up the hydrogen bonding between the alcohols which would result in fewer intermolecular interactions, in addition to increasing the carbon content.
The investigation into using trialkyl orthoformates as a solvent which will produce alkyl-based cation (i.e. Et+) to react with the OH- groups of the phenolic lignin structure in a catalytic amount of acid. The properties (i.e. physical, combustibility, volatility) of differing lengths of the alkyl groups from the solvent (from short chains to fatty chains) will be investigated to discern the most optimal for the purposes of burning for fuel.
The outcome is to produce a liquid lignin-based biofuel. Alternatively, to reduce the crystallinity of lignocellulose for the purposes of pretreatment for bioethanol production.
Terpene – Polymers
The investigation into replacing polymers utilised within the automotive industry with terpene-based bio-renewable alternative. Interest by the automotive industry into bio-renewable products is growing due to pressure exerted by policy makers, stake holders and customers to replace products derived from crude oil. Terpenes are a renewable, cheap, and abundant source of hydrocarbons that is produced naturally and found within forest residues, crops and plants. Additionally, crude sulfate
turpentine (CST) is also produced from the Kraft paper pulping process with approximately 260,000 tonnes of this by-product is produced annually and is estimated to cost $220 per metric tonnes. Previous work has outlined p-cymene as a potential precursor for terephthalic acid (PTA) which is used in the production of many popular polymers, such as polyethylene terephthalate (PET) and polypropylene terephthalate (PPT) which could be used in the automotive industry for the production of materials for a vehicle’s interior (i.e. carpets). Additionally, polycarbonates have been investigated by reacting terpene epoxides (such as α-pinene oxide and limonene oxide) with CO2 that undergo ring-opening co-polymerisation. Polycarbonates are a much-utilised thermoplastic within the automotive industry for door handles, dashboards, and instrument panels.
