The melting transition of methane adsorbed in nanopores has been studied and compared in two type... more The melting transition of methane adsorbed in nanopores has been studied and compared in two types of structures: carbon slits pores and square shaped channels. We show that the nano-confinement not only modifies the temperatures of phase transformation but also induces strong space heterogeneity of the adsorbate. We emphasize the role of the structural heterogeneity on the mechanism of melting: in nanometric pores, each adsorbed layer exhibits different mechanisms of structural transformation and the notion of a unique transition temperature is not well defined.
Defect engineering and metal encapsulation are considered as valuable approaches to fine‐tune the... more Defect engineering and metal encapsulation are considered as valuable approaches to fine‐tune the reactivity of metal–organic frameworks. In this work, various MOF‐808 (Zr) samples are synthesized and characterized with the final aim to understand how defects and/or platinum nanoparticle encapsulation act on the intrinsic and reactive properties of these MOFs. The reactivity of the pristine, defective and Pt encapsulated MOF‐808 is quantified with water adsorption and CO2 adsorption calorimetry. The results reveal strong competitive effects between crystal morphology and missing linker defects which in turn affect the crystal morphology, porosity, stability, and reactivity. In spite of leading to a loss in porosity, the introduction of defects (missing linkers or Pt nanoparticles) is beneficial to the stability of the MOF‐808 towards water and could also be advantageously used to tune adsorption properties of this MOF family.
We report a new type of structural transformation occurring in methane adsorbed in micropores. Th... more We report a new type of structural transformation occurring in methane adsorbed in micropores. The observed methane structures are defined by probability distributions of molecular positions. The mechanism of the transformation has been modeled using Monte Carlo method. The transformation is totally determined by a reconstruction of the probability distribution functions of adsorbed molecules. The methane molecules have some freedom to move in the pore but most of the time they are confined to the positions around the high probability adsorption sites. The observed high‐probability structures evolve as a function of temperature and pressure. The transformation is strongly discontinuous at low temperature and becomes continuous at high temperature. The mechanism of the transformation is influenced by a competition between different components of the interaction and the thermal energy. The methane structure represents a new state of matter, intermediate between solid and liquid.
We characterise the elastic properties of molecular building blocks and how they impact the mecha... more We characterise the elastic properties of molecular building blocks and how they impact the mechanical properties of soft porous crystals.
Scientific literature is replete with descriptions of novel adsorbent materials, making the selec... more Scientific literature is replete with descriptions of novel adsorbent materials, making the selection of such adsorbents for gas storage and separation a trudging task, and often resulting in overlooked materials. Here, we use a high throughput methodology o process a dataset of 28 000 adsorption isotherms from the NIST adsorption database (ISODB) and generate key performance indicators applicable to ambient temperature binary separation on 1500 materials in the collection, with 30 adsorbed guests. The procedure is validated against high-quality laboratory isotherms to confirm the accuracy of the derived indicators. The results are then collated in a powerful online dashboard, which can be used to explore the binary correlations. Finally, we use this toolchain to scrutinize several challenging and industrially relevant case studies and highlight somematerials which may be promising for further analysis.
Material characterisation through adsorption is a widely-used laboratory technique. The isotherms... more Material characterisation through adsorption is a widely-used laboratory technique. The isotherms obtained through volumetric or gravimetric experiments impart insight through their features but can also be analysed to determine material characteristics such as specific surface area, pore size distribution, surface energetics, or used for predicting mixture adsorption. The pyGAPS (python General Adsorption Processing Suite) framework was developed to address the need for high-throughput processing of such adsorption data, independent of the origin, while also being capable of presenting individual results in a user-friendly manner. It contains many common characterisation methods such as: BET and Langmuir surface area, t and α plots, pore size distribution calculations (BJH, Dollimore-Heal, Horvath-Kawazoe, DFT/NLDFT kernel fitting), isosteric heat calculations, IAST calculations, isotherm modelling and more, as well as the ability to import and store data from Excel, CSV, JSON and ...
This work shows that the volume specific surface area could be a reliable criterion for nanomater... more This work shows that the volume specific surface area could be a reliable criterion for nanomaterial identification.
The selective CO2 adsorption performance of a series of functionalized small pore scandium tereph... more The selective CO2 adsorption performance of a series of functionalized small pore scandium terephthalate MOFs was explored by quantum and force-field-based molecular simulations. The NO2 derivative was predicted to be highly selective for CO2 over N2 and CH4, outperforming most of the MOFs as well as other classes of porous solids reported so far. The potential of this solid for physisorption based-applications was further confirmed by (i) an adsorbent performance indicator (API) which exceeds that previously evaluated for many MOFs, (ii) an easy regeneration under mild condition as revealed by high-throughput manometric adsorption experiments although a relatively high CO2 adsorption enthalpy was confirmed by microcalorimetry, and (iii) a good stability under moisture.
X-ray or neutron diffractograms of calcined MCM-41 samples are strongly modified during the sorpt... more X-ray or neutron diffractograms of calcined MCM-41 samples are strongly modified during the sorption phenomenon. Intensity of the main (100) peak (I100) could undergo a non monotonous behaviour. At the sorption beginning I100 increases and I100 strongly decreases in the medium and high loading regimes. These observed intensity modifications in the diffractograms are closely related to the MCM-41 sample and
Scientific literature is replete with data describing novel porous structures, making the selecti... more Scientific literature is replete with data describing novel porous structures, making the selection of an adsorbent for storage and separation applications a trudging task, and often leading to overlooked materials. In this study, we use a high throughput methodology to process a dataset of 32,000 adsorption isotherms from the NIST adsorption database (ISODB) and generate key performance indicators applicable to binary separation on 4400 hosts and 49 guests, with the aim of simplifying the aforementioned choice. The procedure is validated against an internal dataset to gauge the suitability of the derived indicators. The results are then collated in a powerful online dashboard, which can be used to explore material-adsorbate pairs. Finally, we use this toolchain to scrutinize several challenging and industrially relevant case studies and highlight materials which may be promising for further analysis.
Porosity and surface area analysis play a prominent role in modern materials science, where 123 t... more Porosity and surface area analysis play a prominent role in modern materials science, where 123 their determination spans the fields of natural sciences, engineering, geology and medical 124 research. At the heart of this sits the Brunauer-Emmett-Teller (BET) theory,[1] which has been 125 a remarkably successful contribution to the field of materials science. The BET method was 126 developed in the 1930s and is now the most widely used metric for the estimation of surface 127 areas of porous materials.[2] Since the BET method was first developed, there has been an 128 explosion in the field of nanoporous materials with the discovery of synthetic zeolites,[3] 129 nanostructured silicas,[4–6] metal-organic frameworks (MOFs),[7] and others. Despite its 130 widespread use, the manual calculation of BET surface areas causes a significant spread in 131 reported areas, resulting in reproducibility problems in both academia and industry. To probe 132 this, we have brought together 60 labs w...
A promising form of post-combustion technology is CO2 adsorption. In recent years there has been ... more A promising form of post-combustion technology is CO2 adsorption. In recent years there has been very substantial research activity on sorbent materials for CO2 adsorption. Much less attention has been given to issue of process design. In order to have a successful capture process it is important to simultaneously consider both sorbent material and process, different processes will require different sorbent materials to perform optimally. We will review different CO2 adsorption processes with a focus on those being actively pursued. We will look at promising options and discuss areas where further development is required.
The melting transition of methane adsorbed in nanopores has been studied and compared in two type... more The melting transition of methane adsorbed in nanopores has been studied and compared in two types of structures: carbon slits pores and square shaped channels. We show that the nano-confinement not only modifies the temperatures of phase transformation but also induces strong space heterogeneity of the adsorbate. We emphasize the role of the structural heterogeneity on the mechanism of melting: in nanometric pores, each adsorbed layer exhibits different mechanisms of structural transformation and the notion of a unique transition temperature is not well defined.
Defect engineering and metal encapsulation are considered as valuable approaches to fine‐tune the... more Defect engineering and metal encapsulation are considered as valuable approaches to fine‐tune the reactivity of metal–organic frameworks. In this work, various MOF‐808 (Zr) samples are synthesized and characterized with the final aim to understand how defects and/or platinum nanoparticle encapsulation act on the intrinsic and reactive properties of these MOFs. The reactivity of the pristine, defective and Pt encapsulated MOF‐808 is quantified with water adsorption and CO2 adsorption calorimetry. The results reveal strong competitive effects between crystal morphology and missing linker defects which in turn affect the crystal morphology, porosity, stability, and reactivity. In spite of leading to a loss in porosity, the introduction of defects (missing linkers or Pt nanoparticles) is beneficial to the stability of the MOF‐808 towards water and could also be advantageously used to tune adsorption properties of this MOF family.
We report a new type of structural transformation occurring in methane adsorbed in micropores. Th... more We report a new type of structural transformation occurring in methane adsorbed in micropores. The observed methane structures are defined by probability distributions of molecular positions. The mechanism of the transformation has been modeled using Monte Carlo method. The transformation is totally determined by a reconstruction of the probability distribution functions of adsorbed molecules. The methane molecules have some freedom to move in the pore but most of the time they are confined to the positions around the high probability adsorption sites. The observed high‐probability structures evolve as a function of temperature and pressure. The transformation is strongly discontinuous at low temperature and becomes continuous at high temperature. The mechanism of the transformation is influenced by a competition between different components of the interaction and the thermal energy. The methane structure represents a new state of matter, intermediate between solid and liquid.
We characterise the elastic properties of molecular building blocks and how they impact the mecha... more We characterise the elastic properties of molecular building blocks and how they impact the mechanical properties of soft porous crystals.
Scientific literature is replete with descriptions of novel adsorbent materials, making the selec... more Scientific literature is replete with descriptions of novel adsorbent materials, making the selection of such adsorbents for gas storage and separation a trudging task, and often resulting in overlooked materials. Here, we use a high throughput methodology o process a dataset of 28 000 adsorption isotherms from the NIST adsorption database (ISODB) and generate key performance indicators applicable to ambient temperature binary separation on 1500 materials in the collection, with 30 adsorbed guests. The procedure is validated against high-quality laboratory isotherms to confirm the accuracy of the derived indicators. The results are then collated in a powerful online dashboard, which can be used to explore the binary correlations. Finally, we use this toolchain to scrutinize several challenging and industrially relevant case studies and highlight somematerials which may be promising for further analysis.
Material characterisation through adsorption is a widely-used laboratory technique. The isotherms... more Material characterisation through adsorption is a widely-used laboratory technique. The isotherms obtained through volumetric or gravimetric experiments impart insight through their features but can also be analysed to determine material characteristics such as specific surface area, pore size distribution, surface energetics, or used for predicting mixture adsorption. The pyGAPS (python General Adsorption Processing Suite) framework was developed to address the need for high-throughput processing of such adsorption data, independent of the origin, while also being capable of presenting individual results in a user-friendly manner. It contains many common characterisation methods such as: BET and Langmuir surface area, t and α plots, pore size distribution calculations (BJH, Dollimore-Heal, Horvath-Kawazoe, DFT/NLDFT kernel fitting), isosteric heat calculations, IAST calculations, isotherm modelling and more, as well as the ability to import and store data from Excel, CSV, JSON and ...
This work shows that the volume specific surface area could be a reliable criterion for nanomater... more This work shows that the volume specific surface area could be a reliable criterion for nanomaterial identification.
The selective CO2 adsorption performance of a series of functionalized small pore scandium tereph... more The selective CO2 adsorption performance of a series of functionalized small pore scandium terephthalate MOFs was explored by quantum and force-field-based molecular simulations. The NO2 derivative was predicted to be highly selective for CO2 over N2 and CH4, outperforming most of the MOFs as well as other classes of porous solids reported so far. The potential of this solid for physisorption based-applications was further confirmed by (i) an adsorbent performance indicator (API) which exceeds that previously evaluated for many MOFs, (ii) an easy regeneration under mild condition as revealed by high-throughput manometric adsorption experiments although a relatively high CO2 adsorption enthalpy was confirmed by microcalorimetry, and (iii) a good stability under moisture.
X-ray or neutron diffractograms of calcined MCM-41 samples are strongly modified during the sorpt... more X-ray or neutron diffractograms of calcined MCM-41 samples are strongly modified during the sorption phenomenon. Intensity of the main (100) peak (I100) could undergo a non monotonous behaviour. At the sorption beginning I100 increases and I100 strongly decreases in the medium and high loading regimes. These observed intensity modifications in the diffractograms are closely related to the MCM-41 sample and
Scientific literature is replete with data describing novel porous structures, making the selecti... more Scientific literature is replete with data describing novel porous structures, making the selection of an adsorbent for storage and separation applications a trudging task, and often leading to overlooked materials. In this study, we use a high throughput methodology to process a dataset of 32,000 adsorption isotherms from the NIST adsorption database (ISODB) and generate key performance indicators applicable to binary separation on 4400 hosts and 49 guests, with the aim of simplifying the aforementioned choice. The procedure is validated against an internal dataset to gauge the suitability of the derived indicators. The results are then collated in a powerful online dashboard, which can be used to explore material-adsorbate pairs. Finally, we use this toolchain to scrutinize several challenging and industrially relevant case studies and highlight materials which may be promising for further analysis.
Porosity and surface area analysis play a prominent role in modern materials science, where 123 t... more Porosity and surface area analysis play a prominent role in modern materials science, where 123 their determination spans the fields of natural sciences, engineering, geology and medical 124 research. At the heart of this sits the Brunauer-Emmett-Teller (BET) theory,[1] which has been 125 a remarkably successful contribution to the field of materials science. The BET method was 126 developed in the 1930s and is now the most widely used metric for the estimation of surface 127 areas of porous materials.[2] Since the BET method was first developed, there has been an 128 explosion in the field of nanoporous materials with the discovery of synthetic zeolites,[3] 129 nanostructured silicas,[4–6] metal-organic frameworks (MOFs),[7] and others. Despite its 130 widespread use, the manual calculation of BET surface areas causes a significant spread in 131 reported areas, resulting in reproducibility problems in both academia and industry. To probe 132 this, we have brought together 60 labs w...
A promising form of post-combustion technology is CO2 adsorption. In recent years there has been ... more A promising form of post-combustion technology is CO2 adsorption. In recent years there has been very substantial research activity on sorbent materials for CO2 adsorption. Much less attention has been given to issue of process design. In order to have a successful capture process it is important to simultaneously consider both sorbent material and process, different processes will require different sorbent materials to perform optimally. We will review different CO2 adsorption processes with a focus on those being actively pursued. We will look at promising options and discuss areas where further development is required.
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Papers by Philip Llewellyn