New Advances in Membrane Technology

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Optimized distillation coupled with state-of-the-art membranes for propylene purification

The growing production of polyolefins, mainly polyethylene and polypropylene, currently demands increasing outputs of polymer-grade light olefins. The most commonly adopted process for the separation of olefin/paraffin mixtures is performed by energy intensive high pressure or cryogenic distillation, which is considered the most expensive operation in the petrochemical industry. The use of membrane technology offers a compact and modular solution for capital and energy savings, thanks to process intensification. In this work, we move one step forward in the design of hybrid propane/propylene separation systems, using computer aided modeling tools to identify economically optimal combinations of distillation and state-of-the-art membranes. A model is proposed to optimize a hybrid configuration, whereby the membrane performs the bulk separation and the distillation column is intended for the final product polishing, accounting for membrane investment cost and process operating expenses. The decision variables are the membrane area and the column reflux ratio, and the model is able to calculate the optimal feed trays. The upper-bound properties of selected membranes, which define their performance and reliability criteria, have been studied, benchmarking the economic evaluation against conventional distillation in order to assess the expedience of a hybrid system implementation.Financial support from the Spanish Ministry of Science under the projects CTQ2015-66078-R and CTQ2016-75158-R (MINECO, Spain-FEDER 2014–2020) is gratefully acknowledged. Raúl Zarca also thanks the Universidad de Cantabria for a postgraduate fellowship

Generalized predictive modeling for facilitated transport membranes accounting for fixed and mobile carriers

The present work expands previous modeling knowledge on facilitated transport membranes for olefin/paraffin separation. A new robust and practical mathematical model for the description of light olefin flux in composite polymer/ionic liquid/Ag+ membranes is reported. The model takes into account three different transport mechanisms, i.e., solution-diffusion, fixed-site carrier and mobile carrier transport mechanisms. Fixed-site carrier contribution that appears thanks to the bounding of silver cations with the polymer chains is described through a “hopping parameter”. Furthermore, given that the addition of an ionic liquid to the membrane composition promotes carrier mobility, the inclusion of a dedicated expression is necessary for a realistic description of mobile-carrier transport phenomena. The contribution of each mechanism in weighted based on the membrane composition. In order to check the model suitability, simulated values have been matched to experimental data obtained by continuous flow propane/propylene permeation experiments through PVDF-HFP/BMImBF4/AgBF4 composite membranes, working with 50:50 gas mixtures at different temperature and pressure. The resultant model offers good predictions for olefin flux and provides a very useful tool for process optimization and scaling-up. To our knowledge, this is the first time that mobile and fixed site carrier mechanisms performance are simultaneously modeled considering the influence of temperature, pressure and carrier loading.Financial support from projects CTQ2015-66078-R and CTQ2016-75158-R (MINECO, Spain-FEDER 2014–2020) is gratefully acknowledged. Raúl Zarca also thanks the Universidad de Cantabria for a postgraduate fellowship

Mathematical modelling of entropy generation in magnetized micropolar flow between co-rotating cylinders with internal heat generation

The present study investigates analytically the entropy generation in magnetized micropolar fluid flow in between two vertical concentric rotating cylinders of infinite length. The surface of the inner cylinder is heated while the surface of the outer cylinder is cooled. Internal heat generation (which arises in energy systems) is incorporated. The Eringen thermo-micropolar fluid model is used to simulate the micro-structural rheological flow characteristics in the annulus region. The flow is subjected to a constant, static, axial magnetic field. The surface of the inner cylinder is prescribed to be isothermal (constant temperature wall condition), whereas the surface of the outer cylinder was exposed to convection cooling. The conservation equations are normalized and closed-form solutions are obtained for the velocity, microrotation and temperature. These are thereafter utilized to derive the expressions for entropy generation number, Bejan number and total entropy generation rate. The effects of relevant thermo-physical parameters on the flow, heat and entropy generation rate are displayed graphically and interpreted at length. It is observed that the external magnetic force enhances the entropy production rate is minimum at the center point of the channel and maximum in the proximity of the inner cylinder. This causes more wear and tear at the surface of the inner cylinder. Greater Hartmann number also elevates microrotation values in the entire annulus region. The study is relevant to optimization of chemical engineering processes, nuclear engineering cooling systems and propulsion systems utilizing non-Newtonian fluids and magnetohydrodynamics

A microporous six-fold interpenetrated hydrogen-bonded organic framework for highly selective separation of C 2

A unique six-fold interpenetrated hydrogen-bonded organic framework (HOF) has been developed, for the first time, for highly selective separation of C2H4/C2H6 at room temperature and normal pressure

New Advances in Hydrogenation Processes - Fundamentals and Applications

Hydrogen is one of the abundant elements on earth majorly in the form of water (H2O) and mainly as hydrogen gas (H2). Catalytic hydrogenation is a key reaction that has versatile applications in different industries. The main objective of this book is to bring together various applications of hydrogenation through the perspective of leading researchers in the field. This book is intended to be used as a graduate-level text book or as a practical guide for industrial engineers