Designed Synthesis of Zeolites for Environmental and Biorenewables Catalysis

Lead Research Organisation: University of St Andrews
Department Name: Chemistry

Abstract

Heterogeneous catalysis plays a major role in the synthesis of commodity and fine chemicals, fuels and environmental protection for UK industry and aluminosilicate zeolites are the catalysts of choice for many important reactions in oil refining and petrochemical and automobile emission control. Uniquely among industrial solid catalysts, their performance is directly related to their bulk crystal structure, via important details of their pore structure and the chemical structure of their active sites, but synthesis of new materials has by and large relied on trial-and-error approaches. Our research hypothesis is that enough is now known about the synthesis of zeolites and their action as catalysts to plan and execute the preparation of novel active heterogeneous catalysts for selected expanding catalytic technologies.

This ambitious research program spans structural design, hydrothermal synthesis and catalytic performance testing of zeolite catalysts. It will be facilitated by crystallography, atomistic modelling and in situ spectroscopic methods to predict and elucidate details of the mechanisms of crystallisation and of catalysis over targeted zeolites. The program will build on our recent advances in the design of hypothetical zeolite structures and the targeted preparation of novel zeolites, and in the in situ monitoring by solid state NMR, Raman and X-ray spectroscopies of zeolite preparation and of their catalytic reactions. These reactions are important for hydrocarbon generation from oxygenates and for the selective catalytic reduction (SCR) of unwanted nitrogen oxides with ammonia.

The designed synthesis of new zeolites will target hypothetical frameworks that, under computational screening, show promise for SCR or for oxygenates-to-hydrocarbons. Initial studies will develop 'retrosynthetic', modelling-led, approaches to templating these structures, while extended studies will aim to extend these to devise upscalable, commercially viable approaches.

The work will be performed in close collaboration with the UK's leading commercial catalyst company and will not only prepare novel catalysts with potential advantages of performance and patentability over current materials, but will also develop a fully-connected methodology for the synthesis of new catalysts embedded in a computational and in situ experimental framework for the study of the relationship between structure and catalytic function.

Planned Impact

Heterogeneous catalysis plays a major global role in the synthesis of commodity and fine chemicals, the refinement of hydrocarbon fuels and in environmental protection, and therefore has widespread impact. This research aims to develop a new synthetic and cost-effective route to active and selective new microporous catalysts and to evaluate their performance under realistic conditions.

The new zeolite catalysts will have impact in two broad areas: the control of emissions from automobile and other exhausts and the efficient conversion of biorenewables to fuels and chemicals.

In emission control technologies, catalysts can continue to reduce the levels of toxic nitric oxide emissions from the range of diesel and hybrid diesel/electric vehicles that will be with us for decades. This will improve public health, particularly for inhabitants of heavily built-up urban areas.

The conversion of biomass to produce fuel and organic feedstock chemicals will reduce the need for fossil fuels by replacing them with a renewable resource. In particular, where the biomass comes from sources that are not competitive with food production, this can reduce our dependence on oil reserves.

More specifically, the designed synthesis of new zeolites and the development of cost-effective routes to them will give UK industry a technological advantage and so enhance its competitivity and profitability. Another impact will be to further encourage scientific and industrial careers in the area of heterogeneous catalysis.
 
Description So far, we have developed optimised routes to the preparation of zeolites using metal complexes as templates, and we have worked on raising the Si/Al ratio of existing zeolites to make them more stable. This latter investigation has highlighted a new synthesis mechanism (anion templating) that we are writing up.

The synthesis and detailed structure of the novel templated large pore zeotype STA-28 has been established collaboratively by modelling and experiment, and published.

The rational synthesis approach has been used successfully to prepare a novel small pore zeolite, STA-30(SWY), and its activity for NH3 SCR of NO has been measured. This work has been published, and follow up studies are underway.

We have tested novel templates suggested to direct the synthesis of the small pore zeotype with the SAV topology, and found one successfully gives the structure. In addition, we have used a template suggested by modelling for the synthesis of a novel small pore zeolite, which has been tested as a catalyst for the selective catalytic reduction of NO and found to be active. This work is being written up.

The specificity of organic structure directing agents in the precursor-mediated synthesis of a promising (known) zeolite catalyst has been established by synthesis, modelling. Raman spectroscopy and in situ NMR.
Exploitation Route Using methodology to prepare new microporous solids

Developing new catalysts for clean air catalysis for diesel exhausts

Developing catalysts for the methanol-to-olefins conversion
Sectors Chemicals,Energy,Transport

 
Description Findings have been taken forward in a patent application.
First Year Of Impact 2020
Sector Chemicals
Impact Types Economic

 
Description Enhancing the Industrial Impact of Fundamental Zeolite Science
Amount £178,753 (GBP)
Funding ID INF\R2\192052 
Organisation The Royal Society 
Sector Charity/Non Profit
Country United Kingdom
Start 01/2020 
End 12/2023
 
Title Designed Synthesis of STA-30: A Small Pore Zeolite Catalyst with Topology Type SWY (dataset) 
Description Raw data deposition on the paper of the same name, with powder diffraction data, solid state NMR data, adsorption data and catalytic data. This corresponds to figures and analyses described in the manuscript or in the Supporting Information. 
Type Of Material Database/Collection of data 
Year Produced 2021 
Provided To Others? Yes  
Impact None 
URL https://risweb.st-andrews.ac.uk/portal/en/datasets/designed-synthesis-of-sta30-a-small-pore-zeolite-...
 
Title Site-Specific Iron Substitution in STA-28, a Large Pore Aluminophosphate Zeotype prepared using 1,10-Phenanthrolines as Framework-Bound Structure Directing Agents (dataset) 
Description Raw data for Publication 
Type Of Material Database/Collection of data 
Year Produced 2021 
Provided To Others? Yes  
Impact patent published on this material 
 
Title Site-Specific Iron Substitution in STA-28, a Large Pore Aluminophosphate Zeotype prepared using 1,10-Phenanthrolines as Framework-Bound Structure Directing Agents (dataset) 
Description  
Type Of Material Database/Collection of data 
Year Produced 2020 
Provided To Others? Yes  
URL https://risweb.st-andrews.ac.uk:443/portal/en/datasets/sitespecific-iron-substitution-in-sta28-a-lar...
 
Description Computational Chemistry for Rational Design of Zeolite Catalysts 
Organisation University of Portsmouth
Country United Kingdom 
Sector Academic/University 
PI Contribution The joint project includes theoretical crystallography and atomistic simulations, materials synthesis and characterisation, in situ monitoring by lasers, X-rays and NMR spectroscopy, and industrial input of resources (materials, testing) Our contribution is materials synthesis and characterisation, and will also include catalytic testing as new materials arise.
Collaborator Contribution Portsmouth University (Paul Cox, Mervyn Shannon, James Mattock) are performing the theoretical crystallography and atomistic simulations. Mervyn Shannon has an extensive database of hypothetical zeolite structures that are being encoded. These are being/will then be searched as targets for synthesis on the basis of their expected stability and catalytic potential by Paul Cox and James Mattock. For the most promising, potential organic templates will be screened by modelling and suggestions passed to Johnson Matthey for their preparation. These organics are passed to us for assessment in synthetic structures. In parallel, the catalytic potential of zeolites is being assessed computationally at Portsmouth in terms of potential actives sites and the stability of intermediates estimated from modelling.
Impact We have jointly published 'Site-specific Iron Substitution in STA-28, a Large Pore Aluminophosphate Zeotype prepared using 1,10-Phenanthrolines as Framework-Bound Structure Directing Agents ' in Angew. Chem. Our work has been in the synthesis and characterisation, which has been aided by computational modelling at Portsmouth. We have two papers in preparation, one on new templates for STA-7 zeotype, the other on understanding the crystallisation of TNU-9, both combining synthesis, characterisation and modelling.
Start Year 2019
 
Description In situ characterisation of designer zeolites 
Organisation University College London
Country United Kingdom 
Sector Academic/University 
PI Contribution We design synthetic routes to zeolites, including new structures, and assess their catalytic activity.
Collaborator Contribution In situ characterisation and monitoring of synthesis of zeolites and of catalysis taking place over zeolites by laser spectroscopy and X-ray diffraction and spectroscopy.
Impact Early stage of collaboration. UCL have begun to look at some of our zeolites by laser spectroscopy.
Start Year 2019
 
Description Partnership and project management of rational design of zeolite catalysts 
Organisation Johnson Matthey
Department Johnson Matthey Technology Centre
Country United Kingdom 
Sector Private 
PI Contribution In this project, my team works on preparing novel zeolites, or developing and understanding novel routes to zeolites, with specific catalytic reactions in view.
Collaborator Contribution Johnson Matthey's role in the project is to manage it, as well as preparing and supplying organic template molecules chosen by another partner, Portsmouth, as being promising for the synthesis of zeolite structures according to computational predictions. Also JM will test promising catalysts on an industrial scale.
Impact While this particular project dates from 2018, when the proposal was written, my group has had a partnership with JM since 2010, including 5 PhD studentships and several short projects. The outcomes overall have included many research papers, PhD theses and several patents. Most recently I have been awarded a Royal Society Industry Fellowship, covering one-half my salary for 4 years, to work at JMTC. (2020-2023) This is built on the relationship established over the last decade.
Start Year 2019
 
Description Oral presentation at AIChE Conference, Boston, 2021 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact R. Chitac, a PhD student in the research Team for this award, gave a presentation entitled 'Designed Synthesis of STA-30: A Small Pore Zeolite Catalyst with Topology Type SWY'
Authors R. Chitac, J. Bradley, N. McNamara, A. Mayoral, A. Turrina, P. A. Wright, November 17th, 2021
Year(s) Of Engagement Activity 2021