Bio-ethanol Upgrading Catalysed by Multifunctional Zeolites

Since 2015, global production of bioethanol from biomass-based feedstocks has exceeded 25 billion gallons per year. The negative environmental impacts derived from the chemical industry's dependence on fossil fuels means that there is an ever-increasing pressure to utilise renewable alternatives. Consequently, the upgrading of bioethanol into higher value chemicals and fuels is of great interest in both academia and industry.
Bioethanol is predominantly used as a drop-in renewable fuel additive to gasoline. Unfortunately, bioethanol is corrosive to most engines and so only low levels (10%) can be added to gasoline without suitable engine modification. Additionally, bioethanol has a lower energy density (70%) than gasoline and is water miscible, potentially causing problems with separation and dilution in storage tanks. Contrastingly, biobutanol, derived from bioethanol, is a much better renewable additive for gasoline engines; it has 90% the energy density of gasoline, is non-corrosive and has limited miscibility with water so it can be blended at higher concentrations, or even be used as a stand-alone biofuel.
Currently, precious metal based, catalysts are typically utilised for the conversion of ethanol to butanol. These catalysts however are unsustainable for industrial manufacture of biobutanol, and their production and disposal are considered both environmentally and economically problematic. Development of effective catalysts from earth abundant, non-toxic materials would therefore overcome a major barrier in the commercialisation of this process.
Zeolites are microporous aluminosilicate materials used as sustainable catalysts in a range of industrial processes such as catalytic cracking. Their highly stable, cage-like structure allows for shape-selective catalysis, and they can be structurally modified to accommodate numerous different active sites, resulting in an ability to catalyse multistep reaction process.
Recent work in the Taylor group at Durham University has shown that zinc oxide (ZnO) supported on zeolites gives rise to very stable ethanol dehydrogenation catalysts (over 120 hours), which is the first step in the ethanol to butanol reaction cascade. This project aims to modify these ZnO/Zeolite catalysts further, with additional active sites to complete the full ethanol to butanol cascade pathway. This will include earth abundant, extra framework metal sites, as well as framework Lewis acid sites. The project will determine how the nature and location of the differing catalytic components affects overall catalytic function, which will provide structure function models for future catalyst design. The location of the different catalytic functionalities will be controlled via a variety of different synthetic approaches. The multistep conversion of ethanol to butanol will be explored using flow reactors coupled with online analysis, and mechanistic pathways will be probed by in-situ infrared spectroscopy.
This project spans multiple EPSRC research areas including bioenergy, catalysis, chemical reaction dynamics and mechanisms, and functional ceramics and inorganics. The research falls under the themes of Energy and Manufacturing the Future, with the primary goal being development of catalysts for biofuel production.

ReNU's enhanced doctoral training programme delivered by three uniquely co-located major UK universities, Northumbria (UNN), Durham (DU) and Newcastle (NU), addresses clear skills needs in small-to-medium scale renewable energy (RE) and sustainable distributed energy (DE). It was co-designed by a range of companies and is supported by a balanced portfolio of 27 industrial partners (e.g. Airbus, Siemens and Shell) of which 12 are small or medium size enterprises (SMEs) (e.g. Enocell, Equiwatt and Power Roll). A further 9 partners include Government, not-for-profit and key network organisations. Together these provide a powerful, direct and integrated pathway to a range of impacts that span whole energy systems.

Industrial partners will interact with ReNU in three main ways: (1) through the Strategic Advisory Board; (2) by providing external input to individual doctoral candidate's projects; and (3) by setting Industrial Challenge Mini-Projects. These interactions will directly benefit companies by enabling them to focus ReNU's training programme on particular needs, allowing transfer of best practice in training and state-of-the-art techniques, solution approaches to R&D challenges and generation of intellectual property. Access to ReNU for new industrial partners that may wish to benefit from ReNU is enabled by the involvement of key networks and organisations such as the North East Automotive Alliance, the Engineering Employer Federation, and Knowledge Transfer Network (Energy).

In addition to industrial partners, ReNU includes Government organisations and not for-profit-organisations. These partners provide pathways to create impact via policy and public engagement. Similarly, significant academic impact will be achieved through collaborations with project partners in Singapore, Canada and China. This impact will result in research excellence disseminated through prestigious academic journals and international conferences to the benefit of the global community working on advanced energy materials.