Thermodynamic descriptions of the chlor-alkali process are sensitive to the treatment of chlorine hydrolysis under concentrated electrolyte conditions. Reported equilibrium constants for this reaction exhibit meaningful variation when extrapolated from dilute solutions, complicating comparison between studies and introducing uncertainty into process-relevant speciation calculations. In this work, UV-Vis spectroscopy is combined with a Pitzer-based thermodynamic framework to examine chlorine hydrolysis in aqueous sodium perchlorate and sodium chloride electrolytes across industrially relevant ionic strengths (0.028 <= Im <= 2.1 mol kg-1) at 298.15 K. A thermodynamically consistent reference value for the chlorine hydrolysis is adopted and used to quantify electrolyte-dependent non-ideal effects through explicit treatment of ionic activity coefficients and water activity. The analysis separates the competing contributions of electrostatic stabilisation and solvent activity suppression, yielding a non-monotonic dependence of the equilibrium position on ionic strength. Comparison of chloride and perchlorate media at matched ionic strengths demonstrates that equilibrium shifts cannot be described by ionic strength alone but depend on electrolyte identity through ion-solvent and ion-ion interactions. The experimental measurements are consistent with the framework in both electrolytes, providing a structured basis for interpreting chlorine hydrolysis in concentrated aqueous systems and for reconciling historical equilibrium data under non-ideal conditions.

Meeting the International Maritime Organization's net-zero target by 2050 necessitates the replacement of marine fossil fuels with sustainable alternatives, such as dimethyl ether (DME). Silicon-doped aluminophosphate (SAPO) solid acid catalysts, particularly the weakly-acidic SAPO-11, can catalyse the selective dehydration of methanol-to-DME with exceptional stability. Herein, we present a combined experimental, computational fluid dynamics, and design of experiments study to augment catalyst efficiency and DME production, and to support scale-up endeavours. Using a four-dimensional design surface, it was found that longer catalyst beds and higher operating temperature increase DME yields, with the catalyst bed length having a more pronounced influence. In contrast, the use of highly concentrated methanol reactant streams had a detrimental effect and this was ascribed to a saturation of the active sites in the SAPO-11 catalyst. Improved single-pass conversions and catalyst longevity on industrial scales can thus be achieved by optimising both the number of acid sites in SAPO-11 and reaction parameters.

Methanol dehydration chemistry is heavily reliant on solid acid catalysts for the formation of a wide range of hydrocarbons. Whilst olefins are routinely formed on strong Br & oslash;nsted acid sites, there is a growing interest in dimethyl ether production, due to its potential as a sustainable fuel alternative, which is compatible with current petroleum infrastructure. The effective formation of dimethyl ether over extended time periods typically favours weaker acid sites. Here, two methanol molecules can couple together, reducing the formation of larger aromatic products that facilitate the methanol-to-olefin process, but which can also facilitate catalyst deactivation. In this manuscript, we use operando diffuse reflectance infrared Fourier transform spectroscopy to probe methanol dehydration on a range of microporous silicon-doped aluminophosphates (SAPO-5, SAPO-11, SAPO-18, and SAPO-34), correlating the findings with catalytic data to highlight the key parameters for an effective methanolto-dimethyl ether catalyst. In doing so, we demonstrate that weaker acid sites play a key role in the production of dimethyl ether by permitting bound methoxy species and unbound methanol molecules to co-exist, triggering dimethyl ether formation.

Microporous solid acid catalysts are widely used in industrial hydrocarbon transformations in both the fuels and petrochemical industries. The specific choice of microporous framework often dictates the acidic properties of the system, such as acid site strength and concentration. In this work we have explored the influence of acid site concentration on butane isomerisation activity and the mechanistic pathway by controlling the quantity of magnesium doped into an aluminophosphate, keeping the acid site strength and framework topology constant. By combining experimental kinetic studies, and theoretical mechanistic studies, we conclude that isobutane formation, from n-butane, predominantly proceeds through a bimolecular pathway. Specifically, the activity of the system is strongly linked to the presence of alkenes, and herein the precise mechanistic roles of the alkenes are explored.

Relationships between catalyst synthesis, structure and performance were investigated. Precise nanoparticle size control was achieved by tailoring solvent volume, drying temperature and solvent polarity. Catalyst performance was rationalised using a novel multidimensional correlation matrix, which considered synthetic, structural and catalytic data. This unique matrix can aid the design of improved catalysts.

The use of solar energy to activate chemical pathways drives developments in photocatalysis. While catalyst optimization is a primary target, the development of novel photocatalytic reactors is also of critical importance. We will present the combination of microstructured optical fibre technology with photocatalysis, creating a novel microreactor. we thus create a system capable of effectively combining photons, liquids, and gases within a monolithic, highly confined, transparent silica geometry showing its activity in photocatalytic hydrogen generation from water. This highlights the importance in developing light propagation properties from optical fibres. Furthermore, repurposing optical fibre technologies for the fabrication of ultrathin ($\lt 20 \mu \mathrm{m}$) glass/ceramic fibres find uses in a wide array of applications, such as catalytic convertor support mats, composite reinforcement and more importantly, electrolytes for the next generation of solid-state batteries. The current state-of-the-art methods for the fabrication of these glass fibres produces large volumes, but has the disadvantage of also producing large amounts of misshapen material, discontinuities, undesirable inclusions and a distribution of different sized fibres. Depending on the final application of the fibres, this can result in discarding $40 \%$ to $95 \%$ of the glass processed. We will present the feasibility of continuously fabricating optical fibre that meet the required minimum dimensions ($\lt 20 \mu \mathrm{m}$) whilst completely eliminate waste by meeting the most demanding fibre size consistency standards used in solid-state batteries.

Achieving our decarbonisation goals for the maritime transport sector requires the bulk production of liquid hydrocarbon fuels, suitable for the existing infrastructure, such as methanol (MeOH). For this, optimisation of fixed bed chemical reactors is vital. Unlike demonstration-scale setups, optimising the design of such reactors using Computational Fluid Dynamics (CFD) models is both cheaper and faster. In this study, using a 2D pseudohomogeneous CFD model, a single tube from a multi-tubular industrial-scale MeOH reactor is simulated. Using available experimental data, the CFD model was validated yielding excellent accuracy, with an average error of 2.6 %. The model identified a temperature hot-spot near the bed entrance, while the predicted pressure drop was 11 % of the operating pressure. Both effects could considerably reduce the efficiency of the reactor, either by catalyst deactivation or by increasing the compressor requirements, respectively. Through a parametric study where the tube's length and diameter were varied within the +/- 50 % range, 53 total cases are produced and solved, creating an extensive pareto set of data for the key output parameters, such as methanol production, pressure, and temperature. A response surface was also generated, revealing the interconnection between the tube's design and the operating parameters. This enabled a performance optimisation of the reactor design for two industrially relevant scenarios, with the optimised reactor achieving a 6.9 % higher MeOH yield and a 75 % reduced pressure drop. Through industrial involvement, the reactor can be further optimised, and would act as a critical foundation for more extensive techno-economic and socio-economic evaluations for sustainable carbon-neutral methanol production.

A highly selective bifunctional catalyst for the one-pot conversion of CO 2 to DME using CuZnO nanoparticles located on SAPO-34 crystals.

The direct/reductive amination of carbohydrate-based furoin and furil with NH 3 /H 2 was investigated to access amine derivatives.

Microporous solid acid catalysts offer a vast amount of control over chemical processes. However, their coveted smaller pores also have several drawbacks, including a limited substrate scope, faster deactivation, and pore blockage. As such, there are significant advantages to introducing mesopores alongside the microporous framework, to create hierarchically porous frameworks. This work explores the influence of adapting our microporous synthetic procedure for silicoaluminophosphate (SAPO-5) to include different shaped carbon nanotemplates. The differing size of the mesopores formed is explored using nitrogen physisorption, transmission electron microscopy and small angle neutron scattering. In this work, we uniquely use small angle neutron scattering for probing hierarchical silicoaluminophosphates synthesised with hard templating methods. Here small angle neutron scattering was able to probe the shape and size of the mesopores and link their accessibility to their catalytic performance.

Catalytic transformations play a vital role in the implementation of chemical technologies, particularly as society shifts from fossil-fuel-based feedstocks to more renewable bio-based systems. The dehydration of short-chain alcohols using solid acid catalysts is of great interest for the fuel, polymer, and pharmaceutical industries. Microporous frameworks, such as aluminophosphates, are well-suited to such processes, as their framework channels and pores are a similar size to the small alcohols considered, with many different topologies to consider. However, the framework and acid site strength are typically linked, making it challenging to study just one of these factors. In this work, we compare two different silicon-doped aluminophosphates, SAPO-34 and SAPO-5, for alcohol dehydration with the aim of decoupling the influence of acid site strength and the influence of confinement, both of which are key factors in nanoporous catalysis. By varying the alcohol size from ethanol, 1-propanol, and 2-propanol, the acid sites are constant, while the confinement is altered. The experimental catalytic dehydration results reveal that the small-pore SAPO-34 behaves differently to the larger-pore SAPO-5. The former primarily forms alkenes, while the latter favors ether formation. Combining our catalytic findings with density functional theory investigations suggests that the formation of surface alkoxy species plays a pivotal role in the reaction pathway, but the exact energy barriers are strongly influenced by pore structure. To provide a holistic view of the reaction, our work is complemented with molecular dynamics simulations to explore how the diffusion of different species plays a key role in product selectivity, specifically focusing on the role of ether mobility in influencing the reaction mechanism. We conclude that confinement plays a significant role in molecular diffusion and the reaction mechanism translating to notable catalytic differences between the molecules, providing valuable information for future catalyst design.

The formation of hybrid plasmonic nanocatalysts made of Au nanoparticles (NPs) combined with catalytically active NPs has gained great attention owing to their interesting properties and efficient catalysis under visible light irradiation. However, the research on the combination of plasmonic metal NPs with unique support frameworks is still limited. In this report, the varying ratio of AuxPdy prepared by the extrusion method on the CuClP framework has been correlated to its optimized catalysis in the Suzuki-Miyaura coupling reaction in dark and under visible light irradiation. The prepared catalysts AuxPdy/CuClP were characterized by spectroscopic techniques to understand the structural and electronic modification with different metal ratios. The presence of bimetallic NPs on the surface was confirmed by HR-TEM measurements and [MCl4](n-) species in the framework were validated by XPS, FT-EXAFS, DR UV-Vis-NIR, and Raman analysis. The obtained results display the superior catalytic performance and highest plasmonic enhancement factor over Au1Pd1/CuClP under visible light irradiation, which was facilely recycled and reused for several cycles. The hot-electron transfer mechanism has been discussed for enhanced catalysis in the plasmon-driven Suzuki-Miyaura coupling reaction. These results are highly significant in the rational design of new plasmonic photocatalysts combined with unique support materials.

Achieving our emission reduction goals requires the bulk production of carbon-neutral fuels and chemicals, which are catalytically produced through heterogeneous fixed bed chemical reactors. To optimise and scale-up these reactors, accurate and validated Computational Fluid Dynamics (CFD) models are crucial. Of especial importance to CFD simulations is the accurate depiction of the 3D bed structure used during the experimental setup. A direct one-to-one coupling between experiments and simulations can be achieved by scanning the experimental bed using computed tomography and reconstructing the scanned images as a 3D geometry for CFD simulations. However, processing of the scanned images is necessary to minimise highly coarse features that could impact the overall mesh size. A highly poly-dispersed lab scale fixed bed reactor, previously scanned and analysed, is processed using various image-processing operations. Depending on the number and the crudeness of the processing operations, the bed is progressively deformed, which impacts both its porosity and its interparticle pore connectivity. The impact of image-processing becomes more evident when the hydrodynamic behaviour, i.e., X-, Y-, and Z-velocity and static pressure, of the beds is explored. CFD simulations revealed highly heterogeneous flow profiles, with the maximum velocity reached being 16-times higher than the average superficial velocity within the bed. Moreover, small modifications in local topological features introduce significant changes to the flow profiles, while the 3D pore interconnectivity was seen to play an equally important role as the interparticle porosity. A particle size study revealed that large particles form less interconnected networks with higher pore volumes, which significantly reduce the flow velocity and the pressure drop experienced by the flow. The generated results yield key insights towards a deeper understanding of the behaviour of fixed bed chemical reactors, highly valuable for catalyst and reactor engineering.& COPY; 2023 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. This is an open access article under the CC BY license (http://creativecommons.org/ licenses/by/4.0/).

Computational Fluid Dynamics (CFD) models are a valuable tool for the design, optimization, and scalingup of fixed bed chemical reactors.However, the realistic representation of the catalytic bed structure and the mesh quality of the 3D geometry is of paramount importance to improve the accuracy of CFD models.For the former, computed tomography (CT) is a non-destructive method to map and generate the internal structure of experimental fixed bed reactors, enabling a direct 1-to-1 coupling between experiments and simulations.In our previous work, the internal structure of highly poly-dispersed fixed bed reactors, formed by sieved particles, was analysed.The particles that formed them displayed a wide range of sizes, shapes, and orientations.Due to the local topological complexity of these beds, meshing and simulating their entire volume would lead to exhaustive computational demands.To reduce these, a suitable sample section should be selected, which accurately represents both the bulk and the radial porosity of the full bed.Three distinct sample sections were quantified here for their accuracy, identifying that, due to the highly heterogeneous nature of the full beds, sample selection is case sensitive.In addition, compared to smaller particles, larger particles form more heterogeneous local structures, thus requiring longer sections to accurately represent the full bed.A selected 10% section was then meshed, and its hydrodynamic profile resolved, to evaluate its mesh independency.The results highlight the importance of choosing a suitable bed section and mesh size to reduce the computational demands, minimise the computational errors, and achieve the desired level of solution detail.

The significant interest in developing hierarchical materials to overcome the traditional limitations of microporous catalysts, has led to a wide range of synthesis protocols being developed. In this work we modify traditional synthetic procedures known to yield highly crystalline microporous materials, by adding a hydrocarbon surfactant, leading to the formation of hierarchical solid-acid zeotypes; silicoaluminophosphates. We show for the first time, that small angle neutron scattering can build a qualitative description of the porosity in hierarchical materials, probing the exact nature of the micropores and mesopores within our system, that can be adapted to any hierarchical system. When combined with positron annihilation lifetime spectroscopy and porosimetry measurements we gain greater insight by exploring the accessibility and interconnectivity of the micropores and mesopores. We show that by varying the quantity of mesoporogen the size and nature of the mesopores can be finely tuned. Further, small angle neutron scattering reveals that mesopores are lined with a silica layer, that strongly influences the accessibility of the micropores. As such we show that our hierarchical materials contain distinct micropores housing stronger Bronsted acid sites, whilst the mesopores are lined with weaker silanol groups. This is complemented with a catalytic study focussing on n-butane isomerisation and ethanol dehydration that highlights the advantages and disadvantages of this design and further probes the influence of these bimodal porous systems on catalytic performance. The properties of hierarchical solid acid materials have been explored combining experimental catalysis findings, neutron scattering and positron lifetime spectroscopy to understand the multi-porous nature of these materials.

Optimization of large-scale fixed particle bed catalytic reactors requires extensive insight into the multi-scale bed structure, even down to the micrometre scale. Theoretical studies of chemical reactors provide a time- and cost-effective means to supporting the optimisation process. However, they rely on simplified assumptions for the particles, e.g. homogeneous perfect spheres. In practise, the preparation of catalytic particles cannot attain this level of uniformity. Typical preparation techniques, such as sieving, are conducted with the aim of obtaining particle size distributions within a pre-defined range, governed by the sizes of the sieves. However, such methods offer limited control in the actual particle sizes and shapes. This paper evaluates the impact of sieving on the resulting particles and overall structural morphology of catalytic beds. The bed structure is quantified using micro-focus computed tomography (µ-CT), enabling the non-destructive examination and analysis of over 150 thousand particles, in terms of particle size, shape, uniformity, and interparticle porosity. Furthermore, the chemical performance of the resulting beds is compared. The detailed characterisation achieved paves the way for the evolution of more rigorous computational models coupling intricate, localised hydrodynamics with realistic chemical processes. Validation of such models at the lab-scale will accelerate the development of more accurate large-scale models.

Computational fluid dynamics (CFD) modeling plays a pivotal role in optimizing fixed bed catalytic chemical reactors to enhance performance but must accurately capture the various length- and time-scales that underpin the complex particle-fluid interactions. Within catalytic particles, a range of pore sizes exist, with micro-pore scales enhancing the active surface area for increased reactivity and macro-pore scales enhancing intraparticle heat and mass transfer through intraparticle convection. Existing particle-resolved CFD models primarily approach such dual-scale particles with low intraparticle macro-porosities as purely solid. Consequently, intraparticle phenomena associated with intraparticle convection are neglected, and their impact in the full bed scale is not understood. This study presents a porous particle CFD model, whereby individual particles are defined through two distinct porosity terms, a macro-porosity term responsible for the particle's hydrodynamic profile and a micro-porosity term responsible for diffusion and reaction. By comparing the flow profiles through full beds formed by porous and solid particles, the impact of intraparticle convection on mass and heat transfer, as well as on diffusion and reaction, was investigated.

Plasmonic catalysis has revealed improved product yield and selectivity in various chemical transformation reactions over the past decade. In this report, the effect of tertiary amine (‐NR 3 ) functionalization on the surface of hierarchically‐porous zeotype (HP‐AlPO‐5) materials to enhance the plasmon‐mediated catalysis, utilizing a combination of the plasmonic antenna (Au) and catalytic reactor (Pd) nanoparticles (NPs) was investigated. The catalysts have been characterized using enhanced techniques such as HAADF‐STEM, FT‐EXAFS, and probe‐based FT‐IR to reveal the proximity and interaction between bimetallic NPs, and thermal stability of amines in the presence of Au or PdAu NPs. Interestingly, a four‐fold enhancement in the Suzuki‐Miyaura coupling reaction product yield was obtained over PdAu/HP‐AlPO‐5‐NR 3 when compared with the analogous plasmonic catalyst with no amine functionalization under visible light irradiation. A range of amines were functionalized and their influence in the nucleation, uniform growth and stabilization of catalytic active site (Pd) and formation of electron‐rich species under visible light irradiation has also been investigated. The presence of tertiary amine in the nanostructured catalyst enhanced the turnover number (TON) significantly under light irradiation conditions in comparison to dark conditions. This study provides an enriched understanding of plasmon‐driven chemistry, where the maximized reaction rate enhancement requires the existence of active metal species and the formation of electron‐enriched species under light irradiation conditions.

Computational Fluid Dynamics (CFD) models are a valuable tool for design, optimization, and scaling-up of fixed bed chemical reactors.However, the realistic representation of the catalytic bed structure and the mesh quality of the 3D geometry is of paramount importance to improve the accuracy of CFD models.For the former, computed tomography (CT) is a non-destructive method to map and generate the internal structure of actual fixed bed reactors, formed by catalytic particles produced by sieving, thus directly coupling experiments with CFD models.Due to the local topological complexity of these beds, however, meshing their entire volume would lead to exhaustive computational demands.To reduce these, a suitable sample section should be selected, which respects the bulk and radial porosity of the full bed as accurately as possible.Three distinct sample sections were quantified here for their accuracy, identifying that, due to the highly heterogeneous nature of the full beds, sample selection is case sensitive.A selected section was then meshed, and its hydrodynamic profile resolved, to evaluate its mesh independency.The results highlight the importance of choosing a suitable bed section and mesh size to reduce the computational demands, minimise the computational errors, and achieve the desired level of solution detail.