The purpose of this thesis is to investigate the feasibility of producing hydrogen with microtubular membranes made of mixed ionic electronic conducting perovskite by membrane-based steam reforming. This process involves water splitting in one side of the membrane followed by oxygen ions transport across the membrane to react with methane in the membrane reaction side. The overall process produces two separate streams of pure hydrogen and syngas. Initial experiments were performed using temperature programmed redox (water oxidation and methane reduction) cycles to investigate the feasibility of three perovskites (Ba0.5Sr0.5Co0.8Fe0.2O3-δ, La0.6Sr0.4Co0.2Fe0.8O3-δ and La0.7Sr0.3FeO3-δ) to produce hydrogen from water splitting. Membrane fragments and powder materials were used during these tests, resulting in La0.6Sr0.4Co0.2Fe0.8O3-δ and La0.7Sr0.3FeO3-δ powder materials showing better activity for hydrogen production than Ba0.5Sr0.5Co0.8Fe0.2O3-δ. However La0.6Sr0.4Co0.2Fe0.8O3-δ presented better performance among all membrane fragments tested under the experiments conditions. Preliminary oxygen permeation and hydrogen production experiments using membranes systems were also carried out with all perovskites; Ba0.5Sr0.5Co0.8Fe0.2O3-δ microtubes presented high oxygen permeation, however low activity for hydrogen production from water splitting. La0.7Sr0.3FeO3-δ microtubes presented low oxygen permeation rates and no activity for hydrogen production, post-operation analysis showed the presence of a strontium/sulfur layer on the microtubes surfaces which may have affected permeation. La0.6Sr0.4Co0.2Fe0.8O3-δ microtubes presented better potential for oxygen permeation and hydrogen production among the other membranes; hence these microtubes were selected for further long term experiments. La0.6Sr0.4Co0.2Fe0.8O3-δ microtubular membrane reactors were tested for long term oxygen permeation followed by membrane-based steam reforming. The membranes were subjected to two known axial temperature profiles in the temperature of 900°C and 960°C. The microtubes showed good stability under reaction conditions, operating over a total operation period of ca 400 hours of oxygen permeation followed by ca 400 hours of steam reforming. The outlet gas composition from both sides (methane and water side) of the membranes were analysed which allowed material a balance. This indicated that the hydrogen production occurred due to oxygen flux across the membrane and not ii just surface reaction. Post-operation analysis of the microtubes revealed the presence of a strontium-enriched dense layer on the water-exposed membrane surface and of crystallites enriched with cobalt and sulfur on the methane feed side surface.

A generally applicable model for mixing in stirred vessels is derived; it is based on the flow patterns and internal circulation rates produced by the impeller which behaves as a submerged pump. The model is solved by means of a new and powerful numerical technique which can be applied to mixing models consisting of any configuration of well mixed stages; it is based on a probabilistic treatment of an ideal mixing stage and leads to a flexible, easy to use and efficient computer programme. The truncated moments, a set of easily measureable and model - independent parameters, are suggested for the characterisation of dynamic responses; the first of these moments provides a measure of the most significant features of the proposed model and, for certain applications, gives a,direct indication of the optimal mode of operation. A simplified version of the general model is shown to fit three quite different turbine stirred systems over a wide range of operating conditions.

The separation of oil in water dispersions is an important process, with research principally concentrating upon polymeric and ceramic filters where the filtration mechanism is predominantly by capture within the depth of the filter. This work utilises novel metal filters which possess a non-tortuous pore channel and so filter by a sieving mechanism. An evaluation of a variety of types of metal surface filters was conducted with a large proportion of the research focusing upon a filter possessing circular pores which open into a conical shape. Rejection of challenging emulsified oil droplets was solely by exclusion due to size at this pore. Enhancement of emulsion filtration was combined with the surface filters using a selection of rod and helical inserts within a tubular filter to modify the flow conditions; in the case of helical inserts to produce a centrifugal velocity upon the less dense oil droplets away from the filter surface. Further filtration enhancement was produced by air backflushing to alleviate fouling of the filter surface and electrolytic generation of bubbles to capture oil drops on bubbles. The latter method increased the overall feed size and should have increased the centrifugal separation by lowering particle or aggregate density. Research is also reported into the mechanism of rejection of emulsified oil droplets using filters with circular pores. The mechanism has been evaluated and shown to depend on the capillary pressure of deformable oil drops impinging upon the pore. A mathematical model is described, which predicts the deformation of drops using the physical properties of contact angle and interfacial tension combined with the properties of pore size, shape and droplet size.

This thesis deals with two major process routes for the direct oxidation of benzene to phenol. The main objective of the first route was to understand the properties of the porous stainless steel (PSS) needed for support of a catalyst deposited onto its surface, to identify the morphologies of the Pd membrane deposited onto the PSS, to design a catalytic membrane reactor, to characterise membrane in terms of its permeability to hydrogen, and then to investigate hydroxylation of benzene using oxygen as an oxidant. It was observed, using Mo or zeolites as a second catalyst and the reactor design affect the productivity and selectivity towards phenol. This research has also shown the effects of the catalytic properties of iron zeolites with a focus on reactions involving the decomposition of nitrous oxide and direct oxidation of benzene to phenol using nitrous oxide as the oxidant. The main objective of this second route was to identify the active sites in the catalysts, and to a design catalyst based on the acquired knowledge. The methodology was to incorporate iron either at framework positions via hydrothermal synthesis of the zeolites followed by controlled migration to extra-framework positions, or directly at extra-framework positions via sublimation of FeCh or liquid ion-exchange. In this project, different catalysts were characterized and their catalytic activities compared. It was observed contaminants such as N-containing compounds, O2, CO, and water affected the catalytic properties and catalyst half-life. In this thesis, two different methods were used to improve productivity when using a PdlPSS membrane. First, changing design of the reactor, and second, using Mo as a second catalyst. It was observed that higher productivity was obtained when the reactor tube was packed with Fe/ZSM-5 and N20 using as the oxidant. From an economic point of view, using N20 in the presence of zeolite in a fixed-bed reactor is expected to offer more advantages than Pd membrane for oxidation of aromatic compounds.

Selective partial oxidation of methane to methanol was investigated over Cu-ZSM-5 with two main objectives: to improve catalytic activity through modification of the catalyst surface; and to work towards a low-temperature, gas phase catalytic process through building an understanding of the catalytic cycle. Na-ZSM-5 was modified by the commercial silylating agent BSTFA, synthesising a range of functionalised catalysts from 0.2-20% silylation by weight. Successful silylation was confirmed by DRIFTS. Following aqueous copper exchange td form functionalised Cu-ZSM-5, analysis by BET and transmission IR revealed selective exchange of catalytically active copper in the zeolite channels at 1-2% silylation, with reduced exchange of inactive copper on the external surface. The latter was also observed during TEM. A large increase in catalytic activity was determined by TPO-MS analysis. Silylation was therefore used to increase the proportion of catalytically active copper present, with potential application in the synthesis of more active catalysts.

In most industrial situations chemical processes operate within "Total Sites", where they are serviced and linked through a central utility system. Established procedures for heat and power integration work well for optimising each process in isolation. However, greater benefits in terms of energy and capital can be obtained by looking at the entire site. Total site integration addresses the task of optimising each process and the utility system in the context of the overall site. Total site integration has only received limited attention. Various attempts have been made to explore the complex interactions between the processes. However the trade-offs between fuel consumption and co-generation have not yet been established. Therefore, design solutions are mainly derived based on intuition. Since a systematic methodology to address the problem does not actually exist, many iterations may be involved in deriving good solutions and attractive design options can be missed. This thesis provides analytical tools that help understand the interactions between site fuel, heat recovery and co-generation. Capital implications are also addressed. Based on these analytical tools, procedures are developed to tackle total site integration problems including retrofits, site expansions and grassroots, in a systematic way. The procedures do not aim to generate a single optimum solution. Developed within the framework of Pinch Analysis, they are based on physical insights and can help engineers obtain good practical solutions. They can be used to scope and screen major design decisions during the conceptual design stage. The concepts developed in this thesis to address process integration in the context of total sites, do not in any way invalidate the existing Pinch Analysis principles for single process optimisation. Rather, being totally compatible to them, they lift Pinch Analysis onto a higher level of perception.

The awareness for the schedule modification under process disturbances so-called rescheduling, has been growing in the area of chemical batch plants. For the last three decades, planning and scheduling have played a practical and crucial role in not only reducing the inefficiency of batch operations, but also increasing the productivity of batch plants. However, the off-line planning/scheduling can be very inefficient, or even infeasible to be performed when particularly certain undesirable disturbances occur during the operation period. In these cases, therefore, the schedule modification will be inevitably required to reduce or minimise the effects of the disturbances arisen. In this sense, a systematic methodology for the schedule modification is needed to support and guide decision-makers and operators. The development of the methodology is the main objective of this thesis, and the focus mainly lies on the integration between scheduling and rescheduling for chemical batch plants. Two different scheduling algorithms have been proposed in this thesis. The formulation (Model I) based on the concept of State-Task Network (STN) is proposed for the scheduling of multipurpose batch processes, while Model II facilitates the scheduling of multiple product batch plants. Both algorithms are based on the deterministic methods, and the global optimality can be guaranteed. Although Model I is formulated as a Mixed Integer Non-Linear Programming (MINLP) problem, the global optimality of Model I is guaranteed due to the convexity proved. On the other hand, Model II results in a Mixed Integer Linear Programming (MILP), hence the global optimality guaranteed. The performances of the scheduling algorithms are far better than other precedent algorithms, and the details of the computational results are shown in the corresponding sections. In particular, these two scheduling algorithms are reutilised as a deterministic-based rescheduling algorithms after certain modification such as fixing variables, adding or removing constraints, change of an objective function, etc. These modifications are highly dependent upon the given conditions, namely, case-by-case basis. Nevertheless, it provides us the good concept in the sense that the global optimality for the rescheduling can be guaranteed if non-convexity does not take place in the models by the modifications. As far as the global optimality for scheduling and rescheduling is guaranteed, the difference between scheduling and rescheduling will be the minimum (or maximum) effect caused by the disturbance occurred. On the other hand, heuristic or rule-based methods have advantages for the simplicity of the adaptation and/or the similarity with the original schedule, even though their optimality is not guaranteed. In multiple product batch plants, a rule-based method by using completion time algorithm is proposed for the processing time delays and unit failures. In contrast, a rule-based method for multipurpose batch processes is based on the recalculation of material balances that will be required for accommodating the losses of intermediates. For the selection of a rescheduling option against the disturbances arisen, the variability test has been performed in order to identify the most sensitive process variability, so called key variability. To identify the key variability, the accumulated loss of profit function has been introduced as a performance index. Then, the key variability against a process variation occurred has been determined by a variation with maximum index. Based on the key variability identified, the determination of a rescheduling option is made by the rescheduling methodology proposed. From the various examples tested, it is shown the that the approach proposed enables to guide for the selection of rescheduling options available by using the concept of key variability, and the identification of key variability provides good guidelines for decision-making of reactive schedule modification.

Integrated processes such as reactive distillation offer the potential for reduced capital and operating costs compared to conventional flowsheets. In this work new tools for the identification of the optimal reactive distillation process with the optimal degree of integration are developed. A conceptual design method based on the boundary value method is used for a set of reactive distillation processes. The combination of a reactive distillation column with a pre-reactor is a valuable alternative to standalone reactive distillation columns. This thesis presents an approach to identify promising designs for such flowsheets and the optimum distribution of the reaction extent between the pre-reactor and the reactive distillation column. The methodology uses a boundary value method for the design of the column; chemical equilibrium is assumed. The column usually consists of a reactive `core', two rectifying sections and one stripping section. This work presents an approach to identify promising designs for standalone reactive distillation columns as well as for reactor - reactive distillation column flowsheets, when reaction kinetics are available. Reaction kinetics are considered and several near-optimal flowsheet designs are generated. A new approach for the conceptual design of double-feed reactive distillation columns is presented. One of the feed streams is situated at the boundary of the reactive section and the other one can be fed into the non-reactive section of the column. Thus the column consists of an additional separating section, which offers the opportunity to add an additional function to the column. The production of methyl acetate is an example for such a column structure. The additional section in that case acts as an extractive distillation zone. Here also chemical equilibrium is assumed. The integration of further separation steps with a reactive distillation column leads to a highly integrated process: a reactive dividing wall column. Within one apparatus, more than two products can be obtained and the capital cost can be reduced drastically. Furthermore, the well-known reduction in energy demand for dividing wall columns compared to a sequence of conventional distillation columns can lead to reduced operating costs. However, the simulation, design and operation of such complex columns is complicated. A novel approach for the conceptual design of reactive dividing wall columns is presented in this work. Chemical equilibrium is assumed on every reactive stage of the column. The use of the concept of product regions and composition manifolds during all proposed design procedures leads to an increased robustness when compared to conventional approaches based on BVMs. Furthermore, the approaches can be used for n-component systems. Several column designs with different design and operating' parameters are identified for each reactive distillation process, allowing the process engineer to compare and choose from a selection of designs. These tools can assist in identifying the optimal degree of integration for reactive distillation processes ranging from reactor - reactive distillation combinations via complex double feed reactive distillation columns with additional separating sections to the most integrated reactive distillation process: the reactive dividing wall column. The new methodology offers an easy to use tool for process engineers, which assists in identifying an economical integrated reaction-distillation process and could lead to increased industrial applications of technologies coupling unit operations.

Thermal treatment of minerals has been researched over the past few decades, with a view to reducing the energy requirements in the comminution process. The use of microwave radiation has proven especially interesting, due to the differential dielectric heating leading to the generation of intergranular fractures, therefore better liberation of minerals and a reduction in the generation of fines, which are notoriously difficult to process. This thesis specifically investigated the effect of microwave pre-treatment on the efficiency of the downstream separation processes used in the minerals industry. If any energy savings that are made in the comminution process are negated by a severely detrimental effect in the separation of valuable mineral from the gangue then this would not make economic sense for microwave pre-treatment to be utilised. Conventional heat treatment, in air, lead to the formation of oxide mineral phases throughout the bulk of the pyrite, galena, ilmenite and molybdenite samples analysed. This heat treatment had no effect on the mineralogy of the chromite sample. Thermal alteration of the kaolinite sample tested also revealed no significant changes. Dielectric measurements of the minerals showed that all would adsorb microwave radiation, apart from chromite and kaolinite. Exposure to microwave radiation did not induce changes in the bulk mineral, as shown by X-ray diffraction analysis. However, use of scanning electron microscopy showed evidence of oxidation of the pyrite surface, and a mineral liberation analyser showed the formation of pyrrhotite and hematite on the surface of the particles.

The revolutionary Alpha process developed by Lucite International (LI) is an industrially advantageous process over the traditional route of acetone cyanhydrin for the production of methyl methacrylate (MMA). The Alpha process entails two stages. The first stage is an homogeneous catalysis process, a methoxycarbonylation reaction which produces methyl propionate (MeP) from ethylene, CO and methanol using a Pd catalyst stabilised with the 1,2-bis(di-tert-butylphosphinomethyl)benzene (dtbpx) phosphine ligand developed by LI. As it is known, kinetics are important for reactor modelling and simulation, interpretation of reaction mechanisms and catalytic phenomena. The kinetics of the methoxycarbonylation reaction are the subject of this research project and have been studied using a 2 L autoclave reactor and a 0.573 ml volume and 11.7 m length capillary microreactor with similar results. A bespoke experimental rig was designed and built to accommodate the micro devices. A theoretical investigation on the significance of mass transfer effects was undertaken to assess the significance of mass transfer limitations and both reactors were found to operate in the kinetic regime. A hydrodynamics study of Taylor flow under reaction conditions in a 6 m, 0.25 mm ID capillary microreactor was conducted to provide better understanding of the flow and improve its characteristics before the execution of kinetic experiments. The effects of methanol and Pd concentration, CO and ethylene partial pressure on the reaction rate have been studied. The reaction was found to be first and zero order with respect to methanol and ethylene respectively while the fractional order of 0.74 was derived with respect to Pd. CO inhibition kinetics were observed for high CO partial pressures and the reaction order was found to shift from positive to negative at pCO equal to 1.8 bar. The effect of temperature has been investigated in the range 80-120 oC and the activation energy was found to be 53 kJ/mol. A molecular level approach was used to derive a rate equation assuming the methanolysis step as the rate-controlling step. A software package was employed for the estimation of the rate parameters at the reaction conditions of 100 oC and 10 bar of gas pressure. Finally, a significant part of this research was spent on the design and development of a mesh microreactor of rectangular shape with dimensions 3 cm x 3 cm x 1.4 mm incorporating a 2 μm silicon nitride mesh with the aim to perform kinetic experiments but unfortunately this device was proved unsuitable for operation at high pressure.