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A spatially orthogonal hierarchically porous acid–base catalyst for cascade and antagonistic reactions

Nature Catalysis volume 3, pages 921–931 (2020)Cite this article

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A Publisher Correction to this article was published on 09 November 2020

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Abstract

Complex organic molecules are of great importance to research and industrial chemistry and typically synthesized from smaller building blocks by multistep reactions. The ability to perform multiple (distinct) transformations in a single reactor would greatly reduce the number of manipulations required for chemical manufacturing, and hence the development of multifunctional catalysts for such one-pot reactions is highly desirable. Here we report the synthesis of a hierarchically porous framework, in which the macropores are selectively functionalized with a sulfated zirconia solid acid coating, while the mesopores are selectively functionalized with MgO solid base nanoparticles. Active site compartmentalization and substrate channelling protects base-catalysed triacylglyceride transesterification from poisoning by free fatty acid impurities (even at 50 mol%), and promotes the efficient two-step cascade deacetalization-Knoevenagel condensation of dimethyl acetals to cyanoates.

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Fig. 1: Substrate channelling in hierarchical pore networks.
Fig. 2: Synthetic route to a spatially orthogonal, acid–base hierarchically porous framework.
Fig. 3: Spatial distribution of Mg and Zr within a hierarchically porous SBA-15 framework.
Fig. 4: Antagonistic reactions in biodiesel production.
Fig. 5: Substrate channelling: esterification and transesterification over acid–base catalysts.
Fig. 6: NMR relaxation-exchange correlation data.
Fig. 7: Cascade deacetalization and Knoevenagel condensation over acid–base catalysts.

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The data that support the findings of this study are available from the corresponding author upon reasonable request.

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  • 09 November 2020

    An amendment to this paper has been published and can be accessed via a link at the top of the paper.

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Acknowledgements

We thank the Australian Research Council for support (LP180100116, IC150100019, DP 200100204 and DP200100313). Electron microscopy access was provided through the Leeds EPSRC Nanoscience and Nanotechnology Research Equipment Facility (EP/K023853/1), the University of Birmingham Nanoscale Physics Laboratory and the Durham University G.J. Russell Microscopy Facility.

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Authors and Affiliations

  1. Department of Chemistry, University College London, London, UK

    Mark A. Isaacs

  2. HarwellXPS, Research Complex at Harwell, Rutherford Appleton Laboratories, Didcot, UK

    Mark A. Isaacs

  3. Department of Chemical Engineering and Analytical Science, University of Manchester, Manchester, UK

    Christopher M. A. Parlett

  4. University of Manchester at Harwell, Diamond Light Source, Harwell Science and Innovation Campus, Didcot, UK

    Christopher M. A. Parlett

  5. Diamond Light Source, Harwell Science and Innovation Campus, Didcot, UK

    Christopher M. A. Parlett

  6. Department of Chemical Engineering, University of Western Australia, Perth, Australia

    Neil Robinson & Michael L. Johns

  7. School of Geography, Earth and Environmental Sciences, University of Plymouth, Plymouth, UK

    Lee J. Durndell

  8. European Bioenergy Research Institute, Aston University, Birmingham, UK

    Jinesh C. Manayil

  9. Department of Chemistry, Durham University, Durham, UK

    Simon K. Beaumont

  10. School of Physical Science and Technology, ShanghaiTech University, Shanghai, China

    Shan Jiang

  11. School of Chemical and Process Engineering, University of Leeds, Leeds, UK

    Nicole S. Hondow

  12. School of Science, RMIT University, Melbourne, Australia

    Alexander C. Lamb, Deshetti Jampaiah, Karen Wilson & Adam F. Lee

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  1. Mark A. Isaacs
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Contributions

A.F.L. and K.W. conceived the work. A.F.L., M.A.I., C.M.A.P. and K.W. planned the experiments. M.A.I. and A.C.L. synthesized materials. S.K.B. and S.J. synthesized Pt NPs. M.A.I., A.C.L. and J.M. performed catalytic testing. M.A.I., C.M.A.P., L.J.D., N.S.H., D.J. and N.R. undertook materials characterization. N.R. and M.L.J. analysed NMR data. M.A.I., C.M.A.P., N.R., M.L.J., K.W. and A.F.L. wrote the manuscript.

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Correspondence to Karen Wilson or Adam F. Lee.

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Extended data

Extended Data Fig. 1 Ordered macropore network of spatially orthogonal acid–base catalyst.

(a) SEM micrograph, and (b) macropore size distribution from Hg intrusion porosimetry of SZ/MgO/MM-SBA-15. Corresponding normal and cumulative size distributions from SEM of (c) macropore diameter, and (d) macropore window diameter. Note that Hg intrusion measures macropore window size and not macropore diameter64.

Extended Data Fig. 2 Acid–base properties of hierarchical porous catalysts.

(a) DRIFT spectra of saturated chemisorbed pyridine adlayers, (b) reactively-formed propene mass spectra following temperature-programmed desorption of chemisorbed propylamine and associated acid site loadings determined from accompanying TGA mass losses, and (c) CO2 mass spectra following temperature-programmed desorption of chemisorbed CO2 with base site loadings from CO2 pulse chemisorption over MM-SBA-15 materials.

Extended Data Fig. 3 Imaging of acid and base sites within spatially orthogonal acid–base catalyst using funtionalised Pt nanoparticles.

(a) HAADF-STEM, and (b) bright-field micrographs of SZ/MgO/MM-SBA-15 treated with 3-mercaptopropionic acid functionalised Pt NPs, and (c) corresponding area-averaged Pt concentrations determined by EDX within highlighted regions of HAADF-STEM image. Analogous (d) HAADF-STEM, (e) bright-field, and (f) corresponding area-averaged Pt concentrations determined by EDX for SZ/MgO/MM-SBA-15 treated with 4-aminothiophenol functionalised Pt NPs. (g) and (h) Raw EDX spectra associated with mesopore and macropore domains in images (c) and (f) respectively.

Extended Data Fig. 4 Catalytic performance of bifunctional nanoparticle catalyst containing co-located acid–base sites.

Tributyrin transesterification (TAG) with methanol in the absence or presence of hexanoic acid (FFA) over MgO/SZ and SZ nanoparticle catalysts, and simultaneous FFA esterification. Error bars represent S.D. of the mean (n = 3). Reaction conditions: 100 mg catalyst, 5 mmol tributyrin or a mixture of 5 mmol tributyrin/5 mol hexanoic acid, 60 cm3 methanol, 0.1 mmol dihexylether as an internal standard, 60 °C under air, 3 h reaction.

Extended Data Fig. 5 Catalytic performance of hierarchical porous catalysts in the cascade deacetalisation and condensation of dimethyl acetals.

Cyanoester yield from cascade deacetalisation and Knoevenagel condensation of benzaldehyde dimethyl acetal (BDMA), 2-furaldehyde dimethyl acetal (FDMA) or anisaldehyde dimethyl acetal (ADMA) with ethyl cyanoacetate after 6 h reaction over SZ/MgO/MM-SBA-15, a 1:1 by weight physical mixture of SZ/MM-SBA-15 and MgO/MM-SBA-15, or without catalyst. Reaction conditions: 25 mg catalyst (except for physical mixture where 25 mg each of monofunctional catalyst was used), 5 mmol dimethyl acetal, 50 mmol ethyl cyanoacetate, 5 mmol deionised water, 5 cm3 toluene, 1 mmol nonane as an internal standard, 50 °C under N2. Error bars represent S.D. of the mean (n = 2).

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Isaacs, M.A., Parlett, C.M.A., Robinson, N. et al. A spatially orthogonal hierarchically porous acid–base catalyst for cascade and antagonistic reactions. Nat Catal 3, 921–931 (2020). https://doi.org/10.1038/s41929-020-00526-5

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