Overview of Membrane Science and Technology in Portugal

Funding Information: Acknowledgments: The authors acknowledge Tiago Araújo for his valuable contribution in writing—original draft preparation—the carbon molecular sieve membranes content. LCT is grateful to Fundação para a Ciência e a Tecnologia (FCT/MCTES) for her assistant researcher contract under Scientific Employment Stimulus (2020.01555.CEECIND). DMFS thanks FCT/MCTES for a research contract in the scope of programmatic funding UIDP/04540/2020. Funding Information: Funding: This work was supported by Associate Laboratory for Green Chemistry—LAQV, which is financed by national funds from FCT/MCTES (UIDB/50006/2020 and UIDP/50006/2020), Research project PTDC/EQU-EPQ/29579/2017 funded by FCT/MCTES “Programa Operacional Regional de Lisboa, FEDER”, project Nanoart PTDC/CTM-BIO/6178/2014 and CeFEMA with grant number 325UID/CTM/04540/2013 funded by FCT/MCTES. Publisher Copyright: © 2022 by the authors. Licensee MDPI, Basel, Switzerland.Membrane research in Portugal is aligned with global concerns and expectations for sustainable social development, thus progressively focusing on the use of natural resources and renewable energy. This review begins by addressing the pioneer work on membrane science and technology in Portugal by the research groups of Instituto Superior Técnico—Universidade de Lisboa (IST), NOVA School of Science and Technology—Universidade Nova de Lisboa (FCT NOVA) and Faculdade de Engenharia—Universidade do Porto (FEUP) aiming to provide an historical perspective on the topic. Then, an overview of the trends and challenges in membrane processes and materials, mostly in the last five years, involving Portuguese researchers, is presented as a contribution to a more sustainable water–energy–material–food nexus.publishersversionpublishe

Diffusion and Adsorption Coefficients of Aromatic Hydrocarbons in Gas Chromatography Capillary Columns

This study focuses on a mathematical description of aromatic species elution peaks from a gas chromatographic BPX5 capillary column. Using the chromatographic peaks, statistical moments are calculated for toluene, naphthalene, phenol and 2-naphthol. This thesis reports two modelling approaches involving laminar gas flow, distribution coefficients (Ks) and diffusion coefficients in the stationary phase (Ds). Firstly, a model with equilibrium adsorption is considered to describe symmetric peaks for toluene and naphthalene. Moreover, a model with non-equilibrium adsorption is proposed to describe asymmetric peaks of phenol and 2-napthol. In addition to the Ks and Ds parameters, this model involves adsorption kinetic constants (kads). Validation of both mathematical models is developed by performing experiments at different carrier gas velocities and column temperatures (Tc). The model equilibrium adsorption, reports that the distribution coefficients, Ks, and the diffusion coefficients (Ds), solely depend on the solute and stationary phase properties. Furthermore, the model under non-equilibrium adsorption provides kads parameters for phenol and 2-naphthol. However, to fit the second moment, M2,exp, a revised model for the BPX5 column involving two classes of sites for solute adsorption is considered: one site with adsorption at equilibrium and the other site with adsorption at non-equilibrium. Thus, this PhD thesis establishes two chromatographic models for aromatic hydrocarbon species peaks eluted from a BPX5 capillary column. Both mathematical models represent an important contribution to the knowledge of solute interactions in capillary columns for GC. These models may potentially have a significant impact on the future of GC analysis of complex mixtures

Carbon dioxide removal from anaesthetic gas circuits using absorbent membrane contactors

Tese de doutoramento. Engenharia Química e Biológica. Faculdade de Engenharia. Universidade do Porto. 200

Carbon molecular sieve membranes for gas separation : study, preparation and characterization

Tese de doutoramento. Engenharia Química e Biológica. Faculdade de Engenharia. Universidade do Porto. 200

Study of new adsorbents and operation cycles for medical PSA units

Tese de doutoramento. Engenharia Química. Faculdade de Engenharia. Universidade do Porto. 200

Process equipment modeling using the moment method

Process equipment models are needed in all stages of chemical process research and design. Typically, process equipment models consist of systems of partial differential equations for mass and energy balances and complicated closure models for mass transfer, chemical kinetics, and physical properties. The scope of this work is further development of the moment method for modeling applications that are based on the one-dimensional axial dispersion model. This versatile model can be used for most process equipment, such as chemical reactors, adsorbers and chromatographic columns, and distillation and absorption columns. The moment method is a numerical technique for partial differential equations from the class of weighted residual methods (WRM). In this work it is shown with examples how the moment method can be applied to process equipment modeling. The examples are: catalyst activity profiles in fixed-bed reactors, dynamic modeling of chemical reactors and fixed-bed adsorbers with axial dispersion, and steady-state and dynamic modeling and simulation of continuous contact separation processes with or without axial dispersion. An innovative field of application of the moment method is continuous-contact separation processes. The advantage of the moment method, compared to the state-of-the-art nonequilibrium stage model, is that the same level of numerical accuracy can be achieved with fewer variables. In addition, the degree of axial dispersion can be controlled precisely since only physical axial dispersion is introduced via the axial dispersion coefficient. When using axial dispersion models, special attention has to be paid to the boundary conditions. Using the moment transformation it is shown that the Danckwerts boundary conditions are appropriate for time-dependent models in closed-closed geometries. An advantage of the moment method, compared to other weighted residual methods such as orthogonal collocation on finite elements, is the ease with which boundary conditions are specified. The boundary conditions do not arise as additional algebraic equations. Instead, they simply appear as additive source terms in the moment transformed model equations. The second part of this thesis deals with the detailed closure models that are needed for process modeling. Relevance of some of the closure models is scrutinized in particular with two test cases. The first test case is gas-liquid mass transfer coefficients in trickle-bed reactors. It is shown that the correlation of Goto and Smith is appropriate for gas-liquid mass transfer coefficients in industrial trickle-bed reactors. The second test case is vapor-liquid equilibrium model parameters for binary systems of trans-2-butene and cis-2-butene and five alcohols. The Wilson model parameters for all binary systems are fitted against measurements with a total pressure apparatus. The measured pressure-composition profiles are compared against predictions by the UNIFAC and UNIFAC-Dortmund methods

Adsorption and diffusion of gases in Cu-BTC

Ph.DDOCTOR OF PHILOSOPH

INTEGRATED ADSORBENT AND PROCESS DESIGN FOR CARBON CAPTURE FROM POWER PLANT FLUE GAS

Ph.DDOCTOR OF PHILOSOPH

Multi-scale Optimization Frameworks for Integrated Process and Material Design and Intensification

Meeting energy and chemical production demands while reducing costs and emissions is a grand challenge. Intensified processes which merge multiple tasks while maintaining performance can significantly reduce equipment footprint, energy input and costs. Effectively designing such processes requires balancing competing trade-offs on multiple levels. A multi-scale framework is developed for simultaneous consideration of operational and material decisions by posing the intensified process design problem as an optimization formulation. Models and constraints related to process operations, process performance, product quality and material properties are incorporated into the framework. The framework is applied to intensify the separation and storage of methane (CHv4) from feed-stocks by exploiting the preferential adsorption properties of zeolites. However, meeting constraints on CHv4 loss and purity while maximizing the storage capacity is a challenge requiring consideration of both process and material decisions. The complete dynamic process model and constraints along with adsorption isotherm models are posed as a nonlinear programming (NLP) problem. Adsorption isotherm data on 178 siliceous zeolite frameworks are obtained using Grand Canonical Monte Carlo (GCMC) simulations. An initialization strategy is developed to aid in optimizing the model using which the top candidate zeolites and their corresponding process conditions are determined for different feed compositions. The analysis is extended to obtain target material property maps by extensively sampling the material property space (Henry coefficient, deliverable capacity, isotherm parameters) using a Latin Hypercube based strategy. Data from publicly available zeolite databases are super-imposed onto these maps to identify the top zeolite structures for process performance and feasibility. Another application studied is the design of a process to integrate COv2 capture and syngas pro-duction using methane feedstocks. The energy intensive periodic pressure changes employed for adsorbent-based COv2 capture are avoided by using a CHv4 rich purge feed to strip the adsorbed COv2 which then becomes feed for syngas production. A data-driven constrained optimization algorithm is applied to identify process conditions which satisfy process specifications and product quality requirements and to determine optimal process decisions for different objectives and feedstocks. The importance of the multi-scale optimization approach in designing novel intensified processes is demonstrated through these applications