Research projects

Greening of alkene epoxidations via use of polymer supported Mo(VI) catalysts for the production of commercially important epoxide building blocks

A cleaner and sustainable alkene epoxidation process technology has recently been developed by our research group in collaboration with the University of Strathclyde and Purolite International Ltd (EPSRC funded). Epoxides are a raw material for a broad range of products, from pharmaceuticals to plastics and paints to adhesives. In industry, the production of epoxides often uses the stoichiometric peracid, such as peracetic acid and m-chloroperbenzoic acid, in batch reactions. The employment of peracids is not an environment friendly synthesis, since equivalent amounts of acid waste are produced. In this research, polymer-supported molybdenum-based catalysts have been employed for batch and continuous epoxidation of alkenes and terpenes, using environmentally benign synthetic procedures. Batch experimental data provided useful information for the continuous epoxidation experiments in multi-functional reactors, such as the RDC and the FlowSyn continuous flow reactor.

Our new process promises to make the epoxides production cheaper, more environmentally friendly, safer and more flexible. This has been achieved by designing the process to operate continuously, rather than as a batch process that takes place in a single unit combining the reactor and separator. This offers the manufacturer significant business flexibility with their customers. Moreover, the process uses a highly selective and stable insoluble catalyst and no solvent, uses the heat from the exothermic reaction to support the distillation step, reduces unwanted side reactions by separation products out as soon as they are formed, and recycles the alcohol by-product as a chemical feedstock.

This new process provides many advantages to potential users: feedstock flexibility, ‘atom efficiency’, flexibility of scale of production, reduced unit costs and improved profitability. Importantly, as well, the new process makes a big impact on the environmental acceptability of epoxide production. Overall, therefore, such an integrated process also provides a more environmentally acceptable process technology, hence contributing to improving the quality of human life. Professor Saha has recently won The Royal Society Brian Mercer Award to study the feasibility of this process for possible commercialisation.

Green processing of advanced functional nanomaterials using supercritical fluid (SCF) technologies

Our group has a strong interest in seeking greener and cleaner chemical synthesis methods for materials synthesis. As such, SCF have been widely employed as an excellent medium for the synthesis of various nanomaterials. The main factors influencing the increased interest in the use of SCF are their potential to replace toxic organic solvents and the simplicity of optimising their properties by altering the pressure. Most conventional chemical reactions using volatile organic compounds are associated with toxicity, the production of large amounts of waste, flammability and non-sustainability. The replacement of organic and toxic solvents by SCF (such as CO2 or water) offers a great advantage in the chemical and environmental fields.

An SCF is a material used in a state above the critical temperature and critical pressure, where gases and liquids can co-exist. They show unique properties that are different from those of either gases or liquids under standard conditions. An SCF has a higher diffusion coefficient, lower viscosity (gas-like), and lower surface tension than a liquid solvent, as well as enhanced mass transport properties. SCF properties can be modified dramatically by small changes in pressure, especially when the critical parameters are being approached.

Graphene nanocomposites from supercrtical CO2

Graphene, a recently discovered material, composed of 1 nm thick layers of carbon packed into a honeycomb network is one of the most promising materials in nanotechnology. Its unique physical, chemical and mechanical properties, including a very high surface area and easy surface modification (offering an attractive substrate for deposition of inorganic nanoparticles) are outstanding and could allow the preparation of nanocomposite materials with unprecedented characteristics. Our group has employed an innovative approach for synthesising graphene-inorganic nanoparticles via the utilisation of supercritical CO2 (sc-CO2), which allows various nanoparticles to be homogeneously grown and dispersed onto graphene (as shown in Figure 1 below).

Atomic force microscopy (AFM) image of a graphene sheet
Transmission electron microscopy (TEM) image of a graphene sheet decorated with nanoparticles

Figure 1. (a) Atomic force microscopy (AFM) image of a graphene sheet; (b) transmission electron microscopy (TEM) image of a graphene sheet decorated with nanoparticles.

sc-CO2 has attracted interest, due to its relatively low critical parameters (critical temperature, TC = 31.1°C, critical pressure, PC = 7.38 MPa), non-flammability, nontoxicity and recyclability. This is a promising strategy for designing, synthesising and developing the next generation functional novel nanomaterials with a broad range of applications, where the simplicity of the reactor design offers great possibilities for the production of the graphene based materials. These materials are currently being studied for a wide range of applications, including photo catalysis and energy related applications.

Continuous hydrothermal flow synthesis (CHFS)

In addition to sc-CO2, our research group has employed continuous hydrothermal flow synthesis (CHFS) for preparing a wide range of functional nanomaterials with a broad range of applications. In the manufacture of inorganic nanomaterials, hydrothermal (superheated or supercritical water) synthesis can offer many advantages over more conventional preparation methods, e.g., lower synthesis temperatures and relatively less processing steps. Generally, the CHFS process involves mixing a controlled flow of superheated or supercritical water (375°C, 24 MPa) with a flow of aqueous metal salt(s) to give rapid precipitation and controlled growth of nanoparticles in a continuous manner. In such processes, control over particle properties such as size and composition is easily achievable. Further, continuous hydrothermal systems offer a short reaction time and the large scale production of nanoparticles is a real possibility.

Biodiesel and biofuels production

A majority of the world’s energy is supplied through petrochemical sources, coal and natural gas. However, a high energy demand from various sectors, global warming, an unstable price and finite availability of petroleum-based oil, and environmental pollution due to the widespread use of fossil fuels make petroleum based energy unreliable. The world energy forum has also predicted that in less than 10 decades the fossil-based oil, including coal and natural gaseous will be depleted. Therefore, it is increasingly necessary to develop renewable energy resources to replace the traditional sources. Biodiesels, in particular, have the following advantages over diesel fuel: they produce less smoke and particulates, have higher cetane numbers, produce lower carbon monoxide and hydrocarbon emissions, they are biodegradable and nontoxic, and they provide better performances in engine lubricity compared to low sulphur diesel fuels. Our research emphasises producing biodiesel of an EN14214 standard using UCO as a feedstock. We have been working on a knowledge transfer collaboration (KTC) project with Uptown Biodiesel Ltd and PricewaterhouseCoopers (PwC) that involves pre-treatment of UCO and process optimisation to achieve biodiesel as per the EN14214 standard.

Biodiesel production facility

Biodiesel production facility at Uptown Biodiesel Ltd.

Conversion of CO2 to value added chemicals and fuels

CO2 emissions have increased to unsustainable levels in the atmosphere, which has led to climate change. The reduction of CO2 emissions has therefore become a global environmental challenge. Chemical engineers have a vital role in tackling CO2 levels in the atmosphere. At LSBU, we are using our expertise to design an environmentally benign green process for the synthesis of value added chemicals from CO2. Our current research focuses on the production of various highly valued organic carbonates in the presence of heterogeneous catalysts using a Parr high pressure reactor. Organic carbonates have many industrial applications, including as useful intermediates in the synthesis of pharmaceuticals polymers and fine chemicals and fuel additives. Our aim is to reduce the complexity of the homogeneous catalytic system by replacing it with a solvent free system (by using heterogeneous catalysts) and thus, enhancing the potential for numerous industrial applications. We are currently investigating a detailed study for the conversion of CO2 to value added chemicals in collaboration with MEL Chemicals, one of the world’s leading producers and suppliers of inorganic chemicals specialising in zirconium based catalysts and hydrotalcites.

High pressure reactor set-up

High pressure reactor set-up.