Peter S. Shuttleworth

The preparation of high-grade bio-oils through the controlled, low temperature microwave activation of wheat straw

The low temperature microwave activation of biomass has been investigated as a novel, energy efficient route to bio-oils. The properties of the bio-oil produced were considered in terms of fuel suitability. Water content, elemental composition and calorific value have all been found to be comparable to and in many cases better than conventional pyrolysis oils. Compositional analysis shows further differences with conventional pyrolysis oils including simpler chemical mixtures, which have potential as fuel and chemical intermediates. The use of simple additives, e.g. HCl, H(2)SO(4) and NH(3), affects the process product distribution, along with changes in the chemical composition of the oils. Clearly the use of our low temperature technology gives significant advantages in terms of preparing a product that is much closer to that which is required for transport fuel applications.

Microwave assisted decomposition of cellulose: A new thermochemical route for biomass exploitation.

A microwave assisted low temperature decomposition process has been developed for production of high quality fuels from biomass. 180 degrees C was identified as key in the process mechanism, as the amorphous region of cellulose softens allowing a microwave induced rearrangement. Proton transfer is then possible under the microwave field resulting in acid catalysed decomposition. This low temperature process has been shown to be suitable for scale-up, producing a high quality char for use as a coal replacement and bio-oil suitable for upgrading to liquid fuel.

Direct Microwave-Assisted Hydrothermal Depolymerization of Cellulose

A systematic investigation of the interaction of microwave irradiation with microcrystalline cellulose has been carried out, covering a broad temperature range (150 → 270 °C). A variety of analytical techniques (e.g., HPLC, (13)C NMR, FTIR, CHN analysis, hydrogen-deuterium exchange) allowed for the analysis of the obtained liquid and solid products. Based on these results a mechanism of cellulose interaction with microwaves is proposed. Thereby the degree of freedom of the cellulose enclosed CH2OH groups was found to be crucial. This mechanism allows for the explanation of the different experimental observations such as high efficiency of microwave treatment; the dependence of the selectivity/yield of glucose on the applied microwave density; the observed high glucose to HMF ratio; and the influence of the degree of cellulose crystallinity on the results of the hydrolysis process. The highest selectivity toward glucose was found to be ~75% while the highest glucose yield obtained was 21%.

Use of green chemical technologies in an integrated biorefinery

A new concept is demonstrated for an integrated close to zero waste wheat straw biorefinery combining two novel green technologies, CO2 extraction and low temperature microwave pyrolysis, to produce a variety of products, including energy and CO2 which can be internally recycled to sustain the processes. CO2 adds value to the process by extracting secondary metabolites including fatty acids, wax esters and fatty alcohols. Low temperature microwave pyrolysis (<200 °C) is shown to use less energy and produce higher quality oils and chars than conventional pyrolysis. The oils can be fractionated to produce either transport fuels or platform chemicals such as levoglucosan and levoglucosenone. The chars are appropriate for co-firing. The quality of the chars was improved by washing to remove the majority of the potassium and chlorine present, lowering their fouling potential. The economic feasibility of a wheat straw biorefinery is enhanced by intergrating these technologies.

Valorisation of Orange Peel Residues: Waste to Biochemicals and Nanoporous Materials

FRUIT FOR THOUGHT: Low-temperature microwave hydrothermal processing of orange peel not only enables the separation of the major components but also adds further value through the production of other high-value products: pectin and D-limonene, together with a rare form of mesoporous cellulose, are produced in a single step, without added acid. A process temperature change enables the conversion of D-limonene to α-terpineol.

The importance of being porous: polysaccharide-derived mesoporous materials for use in dye adsorption

The controlled pyrolysis of mesoporous polysaccharide-derived materials, from starch and alginic acid, formed carbonaceous materials (Starbons®) and were demonstrated as efficient materials for the removal of dyes from wastewater. The resulting materials were characterised by solid-state NMR, N2 adsorption porosimetry, FT-IR, scanning electron microscopy (SEM) and tunnelling electron microscopy (TEM). The material’s efficiency for dye adsorption was tested using methylene blue (MB) and acid blue 92 (AB) dyes. Adsorption data indicated that the mesoporosity of the material had a far greater influence on the adsorption capacity and speed of adsorption, than high surface area alone. Mesoporous Starbon® (A300) was evaluated against commercially available activated carbon (Norit) and demonstrated a superior adsorption capacity of MB; 186 mg g−1vs. 42 mg g−1. The kinetic activity of Starbon® was also determined with A800 showing the fastest rate of adsorption compared to S800 and Norit, suggesting that it is a more suitable material for water purification.

Microwave-mediated pyrolysis of macro-algae

Macro-algae (seaweed) is an abundant and, for the most part, under-utilised resource. This study has shown that microwave (MW)-mediated pyrolysis of seaweed occurs at extremely low temperatures and produces chemical rich bio-oils which are rich in aromatics, sugars and other high value chemicals.

Thermosetting resin based on epoxidised linseed oil and bio-derived crosslinker.

Thermosetting resins were synthesised from epoxidised linseed oil (ELO) in combination with a bio-derived diacid cross linker (Pripol 1009) in the presence of amine catalysts (triethylamine (TEA), 1-methylimidazole (1-MeIm), 2-methylimidazole (2-MeIm), 1,8-diazabicyclo [5.4.0] undec-7-ene (DBU) and 4-dimethylaminopyridine (DMAP), yielding a 99.5% bio-derived, highly flexible transparent film, with significant water resistance. It was demonstrated that the mechanical and thermal properties of the resulting films were significantly influenced by the type of amine catalyst selected. The use of catalysts significantly enhanced the mechanical properties of the films; tensile strength improved by up to 545% (DMAP), Youngs modulus improved by up to 422% (2-MeIm) and elongation at break improved by 14–84%. An infrared spectroscopic study coupled with simultaneous thermal analysis and modulated differential scanning calorimetry (MDSC) was undertaken in an attempt to elucidate the curing mechanism. Epoxide ring opening is clearly evidenced by infrared spectroscopy and the studies suggest that DMAP probably aids crosslinking between ELO and Pripol 1009 via epoxide ring opening, followed by etherification, due to its good nucleophilicity. The optimum DMAP catalyst loading giving the highest value of Youngs modulus was determined at 1% with respect to the total resin weight. Higher concentrations of DMAP (5% wt) decreased the Youngs modulus.

Applications of nanoparticles in biomass conversion to chemicals and fuels

Biorefineries are facilities that process biomass into fuels, power and value-added chemicals and with the increasing population and depleting petroleum reserves they are fast becoming more important to society. The technology required to process a wide variety of biomass types can be highly complex due to potentially unknown, varying or difficult to breakdown chemical structures within them. One of the prospective routes to a successful biorefinery, that can treat a wide range of biomass and produce products with good selectivity, is the use of nanoparticles as heterogeneous catalysts. The potential of nanoparticles to catalyse and modify chemical processes, thereby influencing both the nature of the products and their distribution is seen as highly promising. In this publication, we aim to give an overview of the use of a range of nano-catalysts and nano-enzymatic supports for greener biorefinery processing. Finally, future prospects of greener routes to nanoparticle production and their integration into biomass are discussed.

New insights into the curing of epoxidized linseed oil with dicarboxylic acids

The effect of systematically increasing chain length of a series of linear α,ω-dicarboxylic acids (DCAs) from C6 to C18 diacids and a cyclic diacid, Pripol 1009F, on thermal and mechanical properties of the resultant epoxy thermosets derived from epoxidized linseed oil (ELO) are reported. Different techniques including differential scanning calorimetry (DSC), solvent extraction, FT-IR, NMR, dynamic mechanical analysis (DMA), tensile tests and thermogravimetric analysis (TGA) are used in this study. The results indicated that the obtained epoxy resins were highly crosslinked polymers with only a small fraction of low molecular weight soluble materials. The glass transition temperature (Tg), tensile strength, Youngs modulus, elongation at break and toughness decreased while the thermal stability increased with respect to increasing chain length of DCAs. Interestingly, strain hardening was only observed for adipic acid (C6) sample for which the best mechanical properties observed.