The Clean Synthesis Technology Platform (CSTP), led by Dr Thomas Farmer, promotes the application of green and sustainable technologies, particularly those that can be used to deliver products that meet consumer and legislation requirements. We also champion the utilization of bio-derived platform molecules (building-block chemicals from biomass), and their conversion to products such as monomers and polymers, solvents, surfactants, anti-oxidants and chelators.
Our expertise in developing cleaner synthetic routes and processes makes the production of a range of chemicals possible in a manner which maximises efficiency and minimising waste. We have considerable experience in the development and use of key enabling technologies such as heterogeneous catalysts, bio-based solvents, enzymatic catalysis and microwaves in synthesis, all of which can enhance processing and are considered as cornerstones of Clean Synthesis.
Our diverse expertise supports the development of biorefineries (fig 1), both by demonstrating the valuable products that can be produced sustainably and providing the key enabling technologies to bring about the required synthesise.
Figure 1: CSTP and the biorefinery
The CSTP undertakes research into both the synthesis and use of bio-based platform molecules, these are defined as:
“…a bio-based (or bio-derived) chemical compound whose constituent elements originate wholly from biomass (material of biological origin, excluding fossil carbon sources), and that can be utilised as a building block for the production of other chemicals.” 
They are typically small, relatively simple molecules of low cost and ideally high production volumes (or at least the potential to be produced on scale), and are seen as the bio-based equivalent to crude-oil derived base chemicals (e.g. ethane, propene and benzene).
Platform molecules typically contain significantly more heteroatom content then traditional crude-oil derived base chemicals, and therefore most of our research focuses on maximising the use of this inherent increased chemical functionality (fig 1). The CSTP have recently been involved in the development of the UKBioChem10, a list of the top platform molecules that industry and academia in the UK should focus research effort towards.
Figure 1: From biomass to bio-based product via Platform Molecules
The CSTP has prepared a range of key derivative chemicals from platform molecules, these being precursors to a range of products that include solvents, monomers, polymers, surfactants, antioxidants, metal chelators and catalysts (fig 2).[3-8]
Figure 2: The use platform molecules as demonstrated in the CSTP
For more information about this topic, contact Dr Thomas Farmer.
Heterogeneous catalysis represents one of the key technologies in cleaner synthesis. Facile recovery and reuse of heterogeneous catalysts means that their application can often reduce the environmental damage caused by traditional chemical processes and reactions. The CSTP remains active in the development of new heterogeneous catalysts, in applying them in reaction involving platform molecules and in their characterisation via a range of available analytical tools (N2 porosimetry, solid-state NMR, SEM, TEM etc.).
In collaboration with Professor Mark Mascal (UC Davis) we have shown that a porous lignin-derived solid support can be easily recovered during the biorefinery process for converting polysaccharides in lignocellulose into CMF. This recovered solid support can have its textural and polar properties fine-tuned through thermal treatment and can be easily sulfonated to produce a reusable solid acid catalyst (fig 1).
Figure 1: CMF-lignin: a novel mesoporous heterogeneous catalyst direct from a biorefinery process
We have previously demonstrated that simply lab-grade K60 silica can be thermally treated and result in an effective catalyst for the direct formation of amides from aniline and a range of carboxylic acids. This was further extended to show that mesoporous silicas reduce the overall catalyst loading required and also that the system opperates effectively in flow. Recently we have demonstrated how computational modeling allows for prediction of reagent solubility and product precipitation, meaning a recirculating system is effective and that high boiling point (and therefore lower voc releasing) solvents such as p-cymene can be used (fig 2).
Figure 2: Computational guidance to enhance catalyst performance in a continuous recirculating amidation
Many of the platform molecules that we work with are either monomers themselves or are precursors to monomers. As such we continue to work extensively in the development and application of new bio-based monomers and polymers. Two major research projects support our activities in this area: EPSRC project (Sustainable Polymers, EP/L017393/1) studying the formation of various polymer classes using bio-derived platform molecules and waste carbon dioxide; BBSRC/IUK project (EnzPoly, BB/N023595/1) investigating the use of new bio-based monomers for the synthesis of polymers via enzymatic catalysis, and the influence of this on the physical properties and bio-degradability of the resultant plastics.
In collaboration with Professor Mark Mascal at UC Davis we developed a range of novel polyesters whose monomers are all derivable from single platform molecule, 5-(chloromethyl)furfuryl, where the inclusion of “methyl-branching” in the diols and diesters was found to enhance the properties of films formed [1,2]:
Figure 1. Novel methyl-branched polyesters from 5-(chloromethyl)furfurl
Over several years we have looked to exploit the chemicals functionality of itaconic acid in formation of polymers and are particularly interested in its unsaturated polyesters. The lateral C=C of itaconate is ideal for post-polymerisation modification, this allowing the polymers final properties to be fine-tuned and enhance, for example adding metal-chelating pendants [3-6]:
Figure 2. Synthesis of and use of unsaturated polyesters of itaconic acid
Further to this we have also shown how itaconate anhydride reacts directly with furfuryl alcohol (also bio-based) in a combined Diels-Alder addition and lactonisation to form an novel oxo-norbornene product. Remarkably the reaction is 100% atom economic and can be carried out without solvent and the need for the catalyst. Esterification of the carboxylic acid group yields monomers that can be polymerised via ring-opening metathesis polymerisation :
Figure 3. Novel ROMPable Oxa-norbornenes from the reaction of itaconic anhydride and furfuryl alcohol
We have also sought to develop new bio-based non-isocyanate polyurethanes (NIPUs) and have recently shown that a glucose-derived bis-cyclic carbonate can be combined with a lysine derived diamine to form self-foaming NIPU materials :
Figure 4. Wholly bio-basde non-isocyanate polyurethanes
Solvents are used in many processes throughout the chemical industry. At present, most are petroleum-derived, many are toxic and some cause damage to the atmosphere.
Using bio-based platform molecules and clean synthetic methodologies, such as flow chemistry, heterogeneous catalysis and enzymatic catalysis, new bio-based solvents can be designed and manufactured. These solvents can be subsequently used for the production of chemical intermediates, polymers and materials.
Figure 2. Synthesis of bio-based solvents, and other products, using bio-based solvents and clean synthetic methodologies from bio-based starting materials.
Current projects include the ReSolve, funded by the Bio-Based Industries Joint Undertaking (BBI-JU) which operates under Horizon 2020. The ReSolve project aims to find replacements for tolueneand N-methylpyrrolidone (NMP), two commonly used toxic solvents with different solvent properties.
Partners in this project including Wageningen University (WUR), Bio-Based Europe Pilot Plant (BBEPP), Nitto Belgium, Circa, Norske Skog, Avantium, Process Design Centre (PDC), TNO, BioDetection Systems (BDS) and Nova Institute, provide expertise in a wide range of areas vital for solvent development.
The polymer industry is under pressure to mitigate the environmental cost of oil-derived plastics. Biotechnologies contribute to the gradual replacement of petrol-based chemistry and the development of new renewable products, leading to the closure of carbon circle. An array of bio-based building blocks are already available on an industrial scale and is boosting the development of new generations of sustainable and functionally competitive polymers. Biocatalysts add higher value to bio-based polymers by catalyzing not only their selective modification, but also their synthesis under mild and controlled conditions. The ultimate aim is the introduction of chemical functionalities thus enlarging the spectrum of advanced applications.
Figure 1: Enzymatic circle for the synthesis, functionalization, modification, and hydrolysis of bio-based polyesters (From: Pellis et al. 2016, Trends Biotechnol., 34, 316-328)
The enzymatic catalysis team main research interests are:
|Dr Thomas Farmer||Clean Synthesis Technology Platform Leader|
|Dr Duncan Macquarrie||Academic|
|Dr James Sherwood||Postdoctoral Researcher|
|Dr Fergal Byrne||Postdoctoral Researcher|
|Roxana Milescu||Research Student|
|Rebecca Donovan||Research Student|
|Ben Trowse||Research Student|