Unravelling mass transport in hierarchically porous catalysts

Isaacs, Mark A.; Robinson, Neil; Barbero, Brunella; Durndell, Lee J.; Manayil, Jinesh C.; Parlett, Christopher M. A.; D’Agostino, Carmine; Wilson, Karen; Lee, Adam F.

doi:10.1039/c9ta01867k

Cited by 74 publications

(57 citation statements)

References 68 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In general, the three typical peaks were indexable as reflections of (100), (110) and (200) planes of ordered mesoporous SBA-15 type material associated with a two-dimensional (2D) hexagonal symmetry (P6mm), which were in accordance with those of other functionalized SBA-15 materials prepared using similar strategies. [27,28]. Accordingly, the low-angle XRD results implied that the 2D hexagonal mesostructure of SBA-15 silica was virtually maintained in the functionalized SBA-15 samples after undergoing the organic sulfonation processes, which was consistent with the N 2 adsorption-desorption isotherms [29].…”

Section: Catalyst Characterizationsupporting

confidence: 74%

See 1 more Smart Citation

Efficient Production of Medium-Chain Structured Phospholipids over Mesoporous Organosulfonic Acid-Functionalized SBA-15 Catalysts

et al. 2019

View full text Add to dashboard Cite

It is highly desirable that efficient recoverable heterogeneous catalysts should be developed to replace the costly biocatalysts used in producing structured phospholipids (SPLs) with medium-chain fatty acids (MCFAs). Thus, mesoporous propyl and phenyl sulfonic acid-functionalized SBA-15 materials synthesized via surface modification methods were investigated for the soybean lecithin interesterification with methyl caprate or caprylate. The physicochemical properties of the synthesized solid acids were deeply studied by small-angle X-ray diffraction, scanning electron microscopy, transmission electron microscopy, Fourier transform infrared and pyridine adsorption, etc. to build the possible structure-performance relationships. The results revealed that amounts of organosulfonic acid groups were successfully grafted onto the SBA-15 support, and most of the surface acid sites contained in the as-prepared organic-inorganic hybrid samples were assigned as strong Brönsted acid sites. Notably, the functionalized SBA-15 materials exhibited promising catalytic behaviors in producing MCFA-enriched SPLs under mild conditions (40 • C, 6 h) when compared with commercial Amberlyst-15 and typical phospholipases or lipases, mostly due to their high surface area, ordered structure and adequate Brönsted acid sites. Besides, the as-prepared materials could be easily recycled five times without obvious deactivation. This work might shed light on alternative catalysts for SPL production instead of the costly enzymes.

show abstract

Section: Catalyst Characterizationsupporting

confidence: 74%

“…According to the results ( Figure 6D), it was noticeable that as high as ca. 27.03 ± 0.98% incorporation of C10:0 and ca. 22.21 ± 1.13% of C8:0 were gained when the catalyst loading was 5 wt%.…”

Section: Catalytic Production Of Spls With Mcfasmentioning

confidence: 99%

Efficient Production of Medium-Chain Structured Phospholipids over Mesoporous Organosulfonic Acid-Functionalized SBA-15 Catalysts

et al. 2019

View full text Add to dashboard Cite

show abstract

“…However, solvent properties can strongly influence catalysis and interfere with the catalytic reaction due to their ability to interact with both reactants and the catalyst. In heterogeneous catalysis solvents may influence a variety of phenomena that can ultimately affect catalytic activity, including solvatochromic parameters, proton transfer, mass transport by diffusion and poisoning of active sites due to competitive adsorption with the reactants . For example, Bertero et al .…”

Section: Introductionmentioning

confidence: 99%

Solvent Effects in the Homogeneous Catalytic Reduction of Propionaldehyde with Aluminium Isopropoxide Catalyst: New Insights from PFG NMR and NMR Relaxation Studies

et al. 2020

Self Cite

View full text Add to dashboard Cite

Solvent effects in homogeneous catalysis are known to affect catalytic activity. Whilst these effects are often described using qualitative features, such as Kamlet‐Taft parameters, experimental tools able to quantify and reveal in more depth such effects have remained unexplored. In this work, PFG NMR diffusion and T1 relaxation measurements have been carried out to probe solvent effects in the homogeneous catalytic reduction of propionaldehyde to 1‐propanol in the presence of aluminium isopropoxide catalyst. Using data on diffusion coefficients it was possible to estimate trends in aggregation of different solvents. The results show that solvents with a high hydrogen‐bond accepting ability, such as ethers, tend to form larger aggregates, which slow down the molecular dynamics of aldehyde molecules, as also suggested by T1 measurements, and preventing their access to the catalytic sites, which results in the observed decrease of catalytic activity. Conversely, weakly interacting solvents, such as alkanes, do not lead to the formation of such aggregates, hence allowing easy access of the aldehyde molecules to the catalytic sites, resulting in higher catalytic activity. The work reported here is a clear example on how combining traditional catalyst screening in homogeneous catalysis with NMR diffusion and relaxation time measurements can lead to new physico‐chemical insights into such systems by providing data able to quantify aggregation phenomena and molecular dynamics.

show abstract

“…NMR relaxation and diffusion experiments are powerful methods for the noninvasive investigation of adsorption and transport phenomena occurring within optically-opaque porous catalysis materials. [77][78][79] Low-field 1 H relaxation-exchange correlation measurements are applied to elucidate the dominant diffusive pathways present throughout our hierarchically porous MM-SBA-15 framework. The NMR pulse sequence for these experiments (Supplementary Figure 14) is detailed elsewhere, 81,82 and comprises two correlated measurements of the transverse nuclear spin relaxation time constant T2 either side of a mixing time of length tmix.…”

Section: Molecular Transport: Low-field Nmr Relaxation-exchange Corrementioning

confidence: 99%

A Spatially Orthogonal Hierarchically Porous Acid-Base Catalyst for Cascade and Antagonistic Reactions

Isaacs¹,

Parlett²,

Robinson³

et al. 2020

Preprint

Self Cite

View full text Add to dashboard Cite

<p>Complex organic molecules are of great importance to academic and industrial chemistry and typically synthesised 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 functionalised with a sulfated zirconia solid acid coating, while the mesopores are selectively functionalised with MgO solid base nanoparticles. Active site compartmentalisation 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 deacetylation-Knoevenagel condensation of dimethyl acetals to cyanoates.<br></p>

show abstract

Unravelling mass transport in hierarchically porous catalysts

Abstract: Hierarchical porous catalysts offer highly connected architectures for enhanced transport of bulky molecules and the sustainable manufacturing of bio-derived platform chemicals and fuels.

Cited by 74 publications

References 68 publications

Efficient Production of Medium-Chain Structured Phospholipids over Mesoporous Organosulfonic Acid-Functionalized SBA-15 Catalysts

Efficient Production of Medium-Chain Structured Phospholipids over Mesoporous Organosulfonic Acid-Functionalized SBA-15 Catalysts

Solvent Effects in the Homogeneous Catalytic Reduction of Propionaldehyde with Aluminium Isopropoxide Catalyst: New Insights from PFG NMR and NMR Relaxation Studies

A Spatially Orthogonal Hierarchically Porous Acid-Base Catalyst for Cascade and Antagonistic Reactions

Contact Info

Product

Resources

About