Sorption enhanced hydrogen production is considered an attractive technology to improve the efficiency of the water gas shift reaction (WGS). It requires the development of selective catalysts and CO2 adsorbents that are sufficiently stable to tolerate cyclic regeneration. The present work focuses on the assessment of the adsorption performance of novel layered double hydroxides (LDHs) supported on multi-walled carbon nanotubes (MWCNTs) and graphene oxide (GO) for application in sorption-enhanced processes. Emphasis is placed on the stability and capacity of hybrids prepared with relatively low carbon support loadings as the CO2 uptake per total volume of composite dictates the size of the industrial units. The coprecipitation of Mg(NO3)2 and Al(NO3)3 onto well-dispersed MWCNTs or GO is shown to be an effective preparation method that ensures an adequate interaction between the LDH and the support, leading to an increase in the CO2 uptake per mass of LDH and improving significantly the stability of the pure LDH. Compared to other supports such as alumina or carbon nanofibers, LDH platelets can be stabilised with lower loadings of nanotubes or graphene oxide. The mass efficiency of the stabiliser is found to be particularly high in the case of GO, possibly due to a better charge and geometric compatibility. Graphene oxide does not to modify significantly the number or chemistry of the CO2 adsorption sites of hydrotalcites but helps to maintain the surface heterogeneity which is otherwise lost during temperature-activated regeneration. The changes in heterogeneity and capacity can be described by the three-parameter Toth isotherm. Alkali ions are shown to increase the capacity of unsupported and supported hydrotalcites without influencing the multicycle stability. Co-adsorption of water enhances the stability and increases the uptake of CO2 without any evidence of carbon gasification in the case of hybrids. Under dry and wet conditions, all materials show fast adsorption kinetics which can be approximated by the linear driving force model. A thorough thermodynamic analysis demonstrates that besides sorption enhanced water gas shift, the in situ removal of CO2 when water gas shift and methanol decomposition (methanol to shift) are conducted simultaneously is an attractive alternative to lift the H2 yield while autothermal conditions are procured. The temperature range of both enhanced processes coincides with the operation window of the adsorbents developed in this research (573-773 K). A preliminary screening shows that Cu/ZnO/Al2O3 and Pt/CeO2 are promising candidates to catalyse water gas shift and methanol decomposition.

Hydrogen is an explosive and flammable gas with a lower explosive limit of just 4% volume in air. It is important to monitor the concentration of hydrogen in a potentially hazardous environment where hydrogen may be released as a by-product in a reaction or used as a principal gas/liquid. A fibre optic based hydrogen sensor offers an intrinsically safe method of monitoring hydrogen concentration. Previous research studies have demonstrated a variety of fibre optic based techniques for hydrogen detection. However the long-term stability of the hydrogen sensor and interrogation system has not yet been assessed and is the focus of this study. In the case of sensor heads being permanently installed in-situ, they cannot be removed for regular replacement, making long-term stability and reliability of results an important feature of the hydrogen sensor. This thesis describes the investigation and characterisation of palladium coated fibre optic sensor heads using two designs of self-referenced refractometer systems with the aim of finding a system that is stable in the long term (~6 months). Palladium was the chosen sensing material owing to its selective affinity for absorbing hydrogen. Upon hydrogen absorption, palladium forms a palladium- hydride compound that has a lower refractive index and lower reflectivity than pure palladium. The refractometers measured the changes in the reflectivity to enable calculation of the concentration of hydrogen present. A low detection limit of 10ppm H2 in air was demonstrated, with a response time of 40s for 1000ppm H2 in air. A further aspect to sensor stability was investigated in the form of sensor heads that had a larger area for palladium coverage. Hydrogen induced cracking in palladium is a common failure mechanism. A hypothesis is presented that a larger sensor area can reduce the probability of catastrophic failure resulting from cracks, which may improve the predictability of the sensor’s performance. Two sensor head designs have been proposed – fibre with a ball lens at the tip and fibre with a GRIN lens at the tip, both of which potentially offer a larger area than the core of a singlemode optical fibre. The limit of detection and response times of the sensor heads were characterised in hydrogen. For long term stability assessment of the sensor head and the interrogation unit, the system was left running for a period of 1 to 4 weeks and the noise and drift in the system was quantified using an Allan deviation plot.

This thesis describes the preparation and characterisation of potential ‘modular’ solid state hydrogen storage solutions for on-board applications. The systems investigated throughout this work are based on reactions between light weight hydroxides and hydrides. In many senses light metal hydroxides can be seen as attractive candidates for hydrogen storage: they are low cost, present negligible toxicity and it is not possible to poison the fuel cell with decomposition products, unlike in nitrogen or boron containing systems. However, as the dehydrogenation products are the respective oxides, the major drawback of such systems lays in the fact the thermodynamics of rehydrogenation are not favourable for onboard applications. Hence, the system must be considered as a ‘charged module’, where the regeneration is performed ex-situ. Dehydrogenation can be achieved through reaction with light metal hydrides such as LiH or MgH2. A wide range of ‘modular’ release systems can be studied, however the most interesting in terms of theoretical gravimetric capacity, kinetics and thermodynamics within reasonable temperature range (RT - 350°C) use magnesium and lithium hydroxide and their hydrate forms. The present work focuses on the full investigation of three main systems: · Mg(OH)2 – MgH2 system · Mg(OH)2 – LiH system · LiOH(·H2O) – MgH2 system (both anhydrous and monohydrate LiOH were used) Mixtures of hydroxides and hydrides were prepared by manually grinding stoichiometric amounts of the starting materials. Further, nanostructuring the reactants was investigated as a means to control the dehydrogenation reaction and enhance the kinetics and thermodynamics of the process. Nanostructured Mg(OH)2 and LiOH(·H2O) have been successfully obtained using both novel and conventional synthetic routes. Reduction of the particle size of both hydrides was effectively achieved by mechanically milling the bulk materials. As detailed throughout Chapters 3, 4 and 5, promising results were obtained when employing nanosized reactants. The onset temperatures of hydrogen release were decreased and the overall systems performances enhanced. Particularly interesting results were obtained for the LiOH – MgH2 system, which exhibit a dramatic decrease of the onset temperature of H2 release of nearly 100 K when working with milled and nanostructured materials with respect to bulk reagents. All systems were characterised mainly by Powder X-ray diffraction (PXD) and simultaneous thermogravimetric analysis (TG-DTA) mass spectroscopy (MS). TG-DTA2 MS experiments were performed to obtain information on the onset and peak temperature of hydrogen release, weight loss percentage and nature and amount of the gases evolved during the reaction. Ex-situ PXD studies have been performed for each system in order to try and identify any intermediate species forming during the dehydrogenation process and ultimately propose a mechanism of H2 release. Since two fundamentally different types of reaction pathway could be proposed for the Mg(OH)2 – LiH system, powder neutron diffraction (PND) was employed for following the reaction in-situ. Developing a complete model of the dehydrogenation process in terms of mechanistic steps was found to be pivotal in order to understand and enhance such systems further.

Hydrogen is considered as an appealing alternative to fossil fuels in the pursuit of sustainable, secure and prosperous growth in the UK and abroad. However there exists a persisting bottleneck in the effective storage of hydrogen for mobile applications in order to facilitate a wide implementation of hydrogen fuel cells in the fossil fuel dependent transportation industry. To address this issue, new means of solid state chemical hydrogen storage are proposed in this thesis. This involves the coupling of LiH with three different organic amines: melamine, urea and dicyandiamide. In principle, thermodynamically favourable hydrogen release from these systems proceeds via the deprotonation of the protic N-H moieties by the hydridic metal hydride. Simultaneously hydrogen kinetics is expected to be enhanced over heavier hydrides by incorporating lithium ions in the proposed binary hydrogen storage systems. Whilst the concept has been successfully demonstrated by the results obtained in this work, it was observed that optimising the ball milling conditions is central in promoting hydrogen desorption in the proposed systems. The theoretical amount of 6.97 wt% by dry mass of hydrogen was released when heating a ball milled mixture of LiH and melamine (6:1 stoichiometry) to 320 °C. It was observed that ball milling introduces a disruption in the intermolecular hydrogen bonding network that exists in pristine melamine. This effect extends to a molecular level electron redistribution observed as a function of shifting IR bands. It was postulated that stable phases form during the first stages of dehydrogenation which contain the triazine skeleton. Dehydrogenation of this system yields a solid product Li2NCN, which has been rehydrogenated back to melamine via hydrolysis under weak acidic conditions. On the other hand, the LiH and urea system (4:1 stoichiometry) desorbed approximately 5.8 wt% of hydrogen, from the theoretical capacity of 8.78 wt% (dry mass), by 270 °C accompanied by undesirable ammonia and trace amount of water release. The thermal dehydrogenation proceeds via the formation of Li(HN(CO)NH2) at 104.5 °C; which then decomposes to LiOCN and unidentified phases containing C-N moieties by 230 °C. The final products are Li2NCN and Li2O (270 °C) with LiCN and Li2CO3 also detected under certain conditions. It was observed that ball milling can effectively supress ammonia formation. Furthermore results obtained from energetic ball milling experiments have indicated that the barrier to full dehydrogenation between LiH and urea is principally kinetic. Finally the dehydrogenation reaction between LiH and dicyandiamide system (4:1 stoichiometry) occurs through two distinct pathways dependent on the ball milling conditions. When ball milled at 450 RPM for 1 h, dehydrogenation proceeds alongside dicyandiamide condensation by 400 °C whilst at a slower milling speed of 400 RPM for 6h, decomposition occurs via a rapid gas desorption (H2 and NH3) at 85 °C accompanied by sample foaming. The reactant dicyandiamide can be generated by hydrolysis using the product Li2NCN.

This work investigates the hydrogen storage potential of a variety of solid state materials. The work has showed their synthesis, structure, morphology and hydrogen storage properties comprehensively. An MgH2 nanocomposite composed of 80% tetragonal α-MgH2 and 18% orthorhombic γ-MgH2 has been prepared for the first time without recourse to high pressure or temperature. By optimizing the ball milling conditions, addition of LiCl and use of THF solvent, the α-/γ-MgH2 nanocomposite so-produced is capable of releasing 6.6 wt% H2 with rapid kinetics, from ca. 260 °C without the use of a catalyst. Moreover, Ti-catalyzed MgH2 offering a capacity of 5.5 wt. % of H2 and superior hydrogen desorption kinetics has been successfully prepared by a novel wet chemical route. The MgH2 material, containing approximately 2~3 wt. % of Ti-additive exhibits hydrogen desorption at a temperature approximately 220 °C lower than pristine MgH2 where pure hydrogen evolution starts at ca. 420 °C via a synergetic effect of mechanochemical treatment and additives. Neutron scattering was employed to study the structure of activated MgD2 and for the first time local disorder in activated MgD2 has been verified using total neutron scattering (PDF fitting). Small angle neutron scattering (SANS) analysis indicates a surface fractal geometry, i.e high degree of surface roughness for activated MgD2 particles, in accordance with SEM analysis suggesting the morphological alteration introduced by mechanochemical treatment. A novel PANI-LiBH4 composite has been successfully fabricated through simple mixing. It is found that PANI-LiBH4 composites dehydrogenates from ca. 200 °C with over 10 wt.% H2 released by 400 °C, significantly outperforming pristine LiBH4. Importantly, rehydrogenation can be achieved under conditions unprecedented for LiBH4 in isolation (200 °C; 100 bar H2 or 330 °C, 20 bar H2 vs. 600 °C, 350 bar H2). Moreover, the PANI-LiBH4 composite can be readily cycled and a new endothermic uptake event at 140 °C, a remarkably low temperature for LiBH4-based systems, suggests that the polymer thermodynamically alters the hydrogenation mechanism. PANI-NaBH4 and PANI-LiH also exhibit vastly improved dehydrogenation properties compared with the respective hydride materials alone. The structures of some first row transition metal halide hydrazinates, TMX2·2N2H4 (TM= Mn, Fe, Co, Ni, Cu and Zn; X= Cl and Br), have been revisited and detailed structural information of three typical complexes, MnCl2·2N2H4, ZnCl2·2N2H4 and MnBr2·2N2H4 have been accurately determined by using a combination techniques of PXD, FTIR and PND. It is also found that TMX2·2N2H4 decomposes at relatively high temperature ( > 250 °C) with massive weight loss due to the dissociation and decomposition of the N2H4 ligand. However the major gas evolution has been determined to be N2 and NH3 with only a minor amount of H2 (and undesired impurity N2H2) released, which makes TMX2·2N2H4 unsuitable for hydrogen storage. Our strategy to combine TMCl2·2N2H4 with LiBH4 to fabricate novel transition metal borohydride hydrazinates has been proven to be successful. Two novel complexes, Mn(BH4)2·2N2H4 and Zn(BH4)2·2N2H4 have been successfully prepared via a facile mechanochemical route with careful manipulation over the milling parameters. The crystal structure of Mn(BH4)2·2N2H4 has been determined using SR-PXD to be isostructural with its parent material MnCl2·2N2H4. The phase evolution behaviour of Zn(BH4)2·2N2H4 has been probed with evidence of various intermediate phases during preparation when various milling conditions were employed. The dehydrogenation properties of both complexes have been studied using DTA-TGA coupled with MS. Mn(BH4)2·2N2H4 and Zn(BH4)2·2N2H4 are very promising materials for off-board hydrogen storage due to their high hydrogen content and useful dehydrogenation properties.

Hydrogen production from bio-resource is a promising option. In order to economically and practically derive hydrogen from biomass on a sustainable scale, novel catalysts are needed to be developed with properties of effective and inexpensive. In this study, initial works include the preparation of Ni/MgO catalysts via different methods including co-precipitation, hydrothermal treatment and wet-impregnation. These catalysts formed solid solutions after calcination at 600 ℃. It was found that hydrothermal treatment increased the specific surface area of the catalyst from 49.7 m2/g to 79.8 m2/g. In addition, the total pore volume and t-plot micropore volume of the hydrothermally treated Ni/MgO (NixMgyO-hydro) increased by a great extent. In the 20 h methanol steam reforming tests, NixMgyO solid solutions prepared via different methods were examined for their catalytic performance, stability and resistance to carbon deposition. Amongst all the catalysts tested, the NixMgyO-hydro catalyst exhibited the highest conversion rate of 97.4mol% with no carbon deposition. This was particularly true when the steam-to-carbon ratio (S/C) was 3. When S/C was 1, similarly, the NixMgyO-hydro showed the highest performance and the lowest amount of carbon deposition. Characterizations of the spent NixMgyO-hydro revealed that it had very low portion of highly ordered carbon on its surface. It is attributed to the rapid removal of atomic carbon, which led to the prevention of carbon accumulation and subsequent transformation into highly ordered structure. The carbon removal mechanism was confirmed by CO2-TPD analysis. The strong basic sites on the NixMgyO-hydro surface enhanced the reaction between deposited carbon and adsorbed CO2. In addition, the catalytic activity of NixMgyO-hydro catalyst was compared with the Ni/γ-Al2O3 catalyst and several other commercial catalysts. Its outstanding performance in steam reforming of methanol was further verified. Although the NixMgyO-hydro catalyst showed good performance in the steam reforming of methanol, it was not the case for ethanol reforming. The NixMgyO-hydro catalyst showed low hydrogen yield and serious carbon deposition during ethanol steam reforming. The low hydrogen yield was caused by the suppression of water-gas shift reaction (WGSR) at high temperatures, whilst the carbon fouling was due to the existence of C-C bonds in ethanol and high selective conversion towards ethylene. Therefore, the modification of the NixMgyO-hydro catalyst was carried out to overcome these drawbacks. Various elements, i.e., Ce, La and Co, were as catalytic promoters and individually added to the NixMgyO-hydro catalyst. Most of the modified catalysts exhibited much higher hydrogen yield at 700 ℃ due to the enhancement of WGSR. Some catalysts, such as Ce- and Co-modified catalysts, showed significant increase in hydrogen yields, which were higher than 80mol% after 30 h of reaction. It is worth mentioning that the La-modified catalysts promoted the hydrogen yield to 53mol% even at low temperature condition (500 ℃), whilst it was only 12.5mol% with the unmodified catalyst at the same temperature. The reason for this was due to the lack of suitable acid sites on La surface, which led to the accelerated formation of acetaldehyde. The advantage of acetaldehyde is it could be decomposed at very low temperature. The formation of carbon on Ce- and La-modified catalysts was also suppressed. The Ce element showed outstanding oxygen storage and release capability to improve the gasification of carbon deposition. Similarly, La2O3 would form La2O2CO3 species which could achieve carbon removal by offering CO2. Subsequently, the modified catalysts were tested with acetic acid (HAc) and phenol as feedstock, both of which are the most common-seen compounds in bio-oil. The results of these tests, such as catalytic performance and anti-carbon abilities, were consistent with the findings in ethanol steam reforming. Most of the modified catalysts showed very high hydrogen yields above 80mol%, which were only 61.9mol% and 73.7mol% for the unmodified NiMgO catalyst in the steam reforming of HAc and phenol, respectively. The better resistant abilities of the modified catalysts over carbon deposition were also confirmed in the steam reforming of HAc and phenol. In order to determine the performance of the catalysts in steam reforming of actual bio-oil, all of the modified catalysts were evaluated based on their performance in the reforming of major model compounds of bio-oil. Three hydrothermally treated catalysts, i.e., 1%Ce/NiMgO, 2%La/NiMgO and 2%Co/NiMgO, were selected and tested. All three catalysts showed carbon conversions above 90mol% and hydrogen yield in excess of 70mol% after 100 h test. The amounts of carbon deposition on these catalysts were also within an acceptable range. It can therefore be concluded that the NixMgyO solid solution with proper modification, i.e. addition of suitable promoter, could be developed as a promising catalyst for hydrogen production via the steam reforming of bio-oil.

In this thesis, four questions are answered about the nature of hydrogen fuel cell (HFC) research, demonstration and development (RD&D) activity in the UK and Germany: 1) how, when and where HFC innovation and diffusion has occurred, 2) which socio-technical factors best explain the nature and pace of HFC innovation and diffusion, 3) what would add and enrich theoretical and methodological approaches to researching HFCs within Innovation Studies, and 4) what policy options follow on from these insights. Firstly, a theoretical contribution involves a critique of the Technologically-specific Innovation Systems (TSISs) heuristic in terms of concepts of agency and structure, system delineation, system indicators and the quality of policy guidance. The knowledge gaps that are revealed suggest methodological modifications to the TSIS approach to event histories in terms of organisational funding – whether events are public, private and public-private – and geographical location should also be included in analyses of HFC innovation and diffusion. Secondly, an empirical contribution is made: the provision of two HFC Technological Innovation System (TIS) case studies from the UK and Germany. This evidence suggests sustained positive feedback between system functions is beginning to occur in this niche sector. Over time, HFC technologies are shown to coevolve and branch along certain pathways - and not others - depending upon structural barriers and enablers encountered by HFC actors. Thirdly, there is a contribution to policy based upon the empirical evidence. State actors should recognize that they can take responsibility for encouraging HFC growth and development. Empirically, public-private partnerships (PPPs), when used in combination with state procurement, were shown to offer HFC actors the greatest levels of agency when cutting unit costs and accelerating diffusion. Ultimately, there may well be hybridised or alternative forms of the TSIS heuristic that fare better in their analyses of HFC innovation and diffusion, however, future lines of HFC research using this approach are not advocated here. I have reached this conclusion because the knowledge gaps that I have identified with the TSIS heuristic are likely insurmountable given the TSIS heuristic’s neofunctionalist ontology.

Healthcare-acquired infections (HAIs) cost the National Health Service (NHS) in England in excess of £1 billion per year. One of the main HAIs is caused by the endospore-forming bacterium Clostridium difficile. The most common cause of healthcare-acquired diarrhoea in the developed world, C. difficile was responsible for around 850 deaths in England and Wales in 2011. To help reduce the spread of the HAI-causing bacteria, terminal disinfection of isolation rooms and wards using hydrogen peroxide vapour is actively promoted. The key advantages of hydrogen peroxide vapour are its high oxidation potential which has been reported to inactivate bacteria, fungi and spores. An additional advantage of hydrogen peroxide vapour is that it is relatively environmentally friendly, breaking down into oxygen and water. Investigation into bacterial inactivation kinetics was undertaken at controlled, steady concentrations of hydrogen peroxide vapour in the range of 10 ppm to 90 ppm. An exposure chamber was designed whereby the bacterial spores could be exposed to constant concentrations of hydrogen peroxide for various exposure times. Bacterial spores (1-log10 to 8-log10 cfu) were filter deposited onto membranes to achieve an even layer for consistent exposure of the hydrogen peroxide vapour to the spores. Bacillus subtilis is often used for method development in bacterial studies; advantages are it has been shown to be highly resistant to hydrogen peroxide vapour and is not a human pathogen. Following the method development, different strains of C. difficile (ribotypes 014, 027, 103 and 220) were exposed to identify differences in resistance. Inactivation models (Chick-Watson, Series-Event, Weibull and Baranyi) were used to fit the data generated using the environmental chamber. Decimal reduction values (D-values) were calculated from the models for comparative studies regarding the inactivation achieved for the different bacteria and different hydrogen peroxide concentrations. The findings from this thesis revealed the Weibull model provides the best fit for most of the data. An initial shoulder period was identified for B. subtilis which was absent for C. difficile inactivation by hydrogen peroxide vapour; B. subtilis is therefore more resistant to hydrogen peroxide disinfection than C. difficile. Typical D-values for B. subtilis and C. difficile when exposed to hydrogen peroxide vapour at a concentration of 90 ppm were 140 and 1 min, respectively. C. difficile inactivation data were used to develop a model to estimate the log reduction that could be achieved during an inactivation cycle based on the concentration-time integral ( ). This model could be used to estimate the log reduction of commercially available hydrogen peroxide decontamination systems; these release a fixed amount of hydrogen peroxide into the room resulting in a peak concentration before decomposition to oxygen and water. Releasing the hydrogen peroxide into the room in this manner results in spatial and temporal variation; this could result in differences in bacterial inactivation in different areas within the room. Using the aforementioned regression model, the inactivation achieved at all locations within the room could be predicted, which could be used to optimise the current hydrogen peroxide decontamination cycles.

This thesis describes the development and characterisation of palladium optical coatings for hydrogen sensing. The main aim of the thesis was to optimise an optically interrogated palladium coated substrate to detect hydrogen at concentrations less than 1% in humid conditions (50-80%). An optical set up was constructed to investigate the change in the coatings in transmission at 650 nm on exposure to varying hydrogen concentrations in dry and wet conditions. Three different optical substrates; Polymer Optical Fibre (POF), Polymethyl methacrylate (PMMA) and glass were evaluated to determine the best support for palladium; criteria of selection were based on hydrogen detection performance in dry and humid condition (50%). PMMA was shown to be the ideal support as effect of humidity on hydrogen detection was minimal. Palladium was deposited by sputter coating technique and the coating thickness demonstrates a dependence on the deposition time and position of the substrate inside the coating chamber. The coating developed showed a response time of 1s at 5%H2, a detection range of 0-9.1% with a demonstrated detection limit of 200 parts per million (ppm) and a predicted limit of detection of 15 ppm. The rate of hydrogen detection was proposed to be diffusion limited for coating thickness up to the threshold thickness. At thicknesses less than the threshold thickness, the rate limiting step was related to the binding force between the coating and the support. The coating performance was unaffected by cross sensitive gases such as hydrogen sulphide, carbon monoxide, methane and ethene. In the presence of Relative Humidity (50-80%), the coating reached a limit of detection at 0.1% H2. However, over exposure to humidity lead to temperature effect which was compensated using a temperature compensation model developed. The surface of the coating developed was characterised by Atomic Force Microscopy (AFM), X-Ray Diffraction (XRD) and X-Ray Photoelectron Spectroscopy (XPS) and revealed that the coating developed is unaffected by the tests carried out through the PhD.

The process of purifying hydrogen gas using pressure swing adsorption columns heavily relies on highly efficient adsorbents. Such materials must be able to selectively adsorb a large amount of impurities, and must also be regenerated with ease. The work presented in this thesis focuses on a novel class of porous solids, metal-organic frameworks (MOFs), and their potential for use as adsorbents in hydrogen purification processes. MOFs are tuneable structures, a property that can be exploited in order to achieve the desired characteristics that are beneficial for a specific application. The design or selection of MOFs for any separation process however, relies on a thorough understanding of the relationship between a framework’s characteristics and its adsorption and selective properties. In order to identify favourable MOF characteristics for the separation of hydrogen from typical impurities a systematic molecular simulation study is performed on a large group of MOFs. Features such as the presence of short linkers, amine groups and additional aromatic rings, and a high density of linker groups are found to increase the adsorbate - framework interaction strength, and reduce the free volume available inside the pores. Both of these effects are shown to enhance MOF selectivity for impurities. Two promising materials, exhibiting desirable features, Mn MIL-53 and MIL-47, are studied further through a variety of approaches. A combination of experimental work and molecular simulations are employed in order to assess the level of flexibility in Mn MIL-53 on uptake of CO2 and CH4. An investigation of the experimental and simulation adsorption and characterization data indicates that the framework undergoes structural changes, in order to accommodate CO2 molecules, but not CH4. The form of the framework during CO2 uptake is also shown to be strongly influenced by temperature. In the case of MIL-47, adsorption isotherms simulated for a wide range of gases overpredict experimental adsorption data, leading to an in-depth investigation of non-porous effects, force field suitability, and framework rigidity. Ab initio molecular dynamics studies of MIL-47 indicate that the benzene dicarboxylate linkers rotate about their symmetry axis to reach more energetically favourable configurations, an effect responsible for the discrepancies between simulated and experimental isotherms. The effect of MOF flexibility on adsorption is further highlighted in a study of Sc2BDC3, a material able to undergo structural changes in order to accommodate a variety of adsorbates. Molecular simulations show that structural changes in the framework are responsible for the creation of additional CO2 adsorption sites as pressure is increased, whereas methanol adsorption sites occupied at extreme pressure are stabilized by the formation of hydrogen bonds. Finally, the exceptionally robust UiO-66(Zr) and UiO-67(Zr) families of MOFs are analysed using a multi-scale simulation study combining molecular level and process-scale computational work, seeking to compare the materials to commercial adsorbents, and assess whether they are suitable for H2 purification through pressure swing adsorption (PSA). Of the four MOFs studied, UiO-66(Zr)-Br is the most promising, as it significantly outperforms commercial zeolites and activated carbons in H2 purification from steam methane reformer offgas.