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Item type:Publication, Access status: with files , Integrating optimal design of experiments and superstructure optimization under uncertainties for the design of membrane processesMembrane processes are attractive options for fluid separations as they enable highly selective separations under mild process conditions. The design and evaluation of membrane processes is however a complex task, due to the large variety of different separation principles and corresponding types of membrane processes, a variety of different membrane materials, and alternative process structures, as well as the limited availability of data and models that is especially a hurdle in the early-stage design of chemical processes. A model- and optimizationbased approach can help to design membrane separation processes systematically but requires the determination of a sufficiently accurate process model that usually requires time-consuming experimental work. In the early stage of process design, there are still many options regarding the process structure and operating parameters, and it is desirable to focus the experimental and modelling efforts only on promising process variants and operating conditions. For this purpose, the current work presents an integrated methodology that enables the application of optimization-based methods in early phase process design applied to a reaction-separation process. The application focusses on the selection and design of the membrane separation as an important aspect of the overall flowsheet. By performing a superstructure optimization in which uncertainties are explicitly considered, a set of promising flowsheet variants can be selected. Instead of a separated design of experiments for the model identification, an integral approach is pursued by selecting the most informative experiments on the basis of the impact of the model uncertainties on the design decisions, in order to quickly determine the most relevant parameters. In the specific case study, the methodology is used for the conceptual design of a membrane process where the membrane is used to separate a co-product from a complex reaction mixture while retaining the expensive homogeneous catalyst. Using the integrated approach only one set of experiments in addition to the initial screening experiments is necessary to identify the optimal flowsheet for the case study.Publicationtype: Journal Article46 13 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Unraveling the influence of dissolved gases on permeate flux in organic solvent nanofiltration – Experimental analysis(2022-08-15); ; ; ; The first step in quantifying the performance of organic solvent nanofiltration membranes are usually lab-scale experiments with respect to flux and rejection. The necessary pressurization of the feed is either realized mechanically by a high-pressure pump or by means of a pressurized inert gas. While the latter option is most frequently applied, the gas may dissolve in the feed mixture and permeate through the membrane, affecting the transport of the other components. This potential effect is commonly neglected, inherently assuming that the gas solubility is negligible. The current study provides a systematic experimental investigation and analysis of the impact of dissolved gases on solvent flux for a hydrophilic DuraMem membrane, with gas solubilities assessed through PC-SAFT. The results prove that a gas with low solubility has a negligible effect on the solvent flux. In contrast, an increasing gas solubility may result in significant gas flux through the membrane with a considerable effect on the solvent flux. Furthermore, the correlation of the solvent flux with the gas solubility in the feed mixture is strongly non-linear. Therefore, gas solubility is recommended to be critically evaluated when conducting OSN experiments, specifically considering the final application. In that context, the permeation of dissolved gas has to be actively accounted for in OSN experiments for gas–liquid systems.Publicationtype: Journal Article52 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Continuous co-product separation by organic solvent nanofiltration for the hydroaminomethylation in a thermomorphic multiphase system(2021-04-01); ; ; ; While homogeneous catalysts can be used to efficiently produce intermediate and specialty chemicals, the separation of the precious catalyst from products, by-products or co-products can be a major challenge. Consequently, novel processes need to be developed to effectively separate and reuse the active catalyst, while avoiding accumulation of the various reaction products. Therefore, this work presents the development and demonstration of a hybrid, continuous reaction and separation process for the catalytic auto-tandem hydroaminomethylation (HAM) reaction. Herein, long-chain alkenes are converted to valuable higher aliphatic amines with high atom economy, while producing only water as co-product. Since the HAM is a rhodium-catalyzed reaction, a thermomorphic multiphase system is used as an integrated catalyst recycling strategy, which is further combined with a membrane-based separation of the co-product via organic solvent nanofiltration. Based on initial screening of various membranes and investigation on the water influence on the phase separation after the reactor, the full process for the HAM of 1-decene with diethylamine with separation of the co-product water was operated continuously for 75 h in a miniplant. The continuous operation of the process successfully demonstrated stable process operation, avoiding a steady accumulation of water while maintaining high catalyst rejection between 97% and 99.3%. The overall leaching of rhodium was kept below 3% of the total amount supplied. This corresponds to a loss of only 11 mg of catalyst per kg of product.Publicationtype: Journal Article160 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Model Discrimination for Multicomponent Distillation – A Geometrical Approach for Total Reflux(2020-07-01); ; ; ; While rate-based models are available in commercial flowsheet simulation tools, packed distillation columns are still mostly designed based on the equilibrium stage model in combination with HETP values. In order to discriminate between both types of models in a simple way, this article proposes an algorithmic test, based on a geometric criterion for total reflux operation. Substantial differences are illustrated especially for wide-boiling mixtures, while component-specific mass transfer rates either increase or reduce the deviation. The derived results are validated by dedicated experiments.Publicationtype: Journal Article55 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Process intensification of thermomorphic multiphase systems for the homogeneously catalyzed hydroaminomethylation in a continuously operated miniplantProcess intensification (PI) is a common tool to obtain a more sustainable, more efficient and more economical way to produce chemicals. As PI can be performed on different levels starting from molecular up to process and plant level, this research shows an efficient way to synthesise amines in the context of high atom economy and low environmental impact. We herein present the development of a continuous process and classification in terms of PI by combining the one-pot hydroaminomethylation (HAM) with a thermomorphic multiphase system (TMS) and organic solvent nanofiltration (OSN).Publicationtype: Conference Paper43 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Choosing the right model for distillation processes in packed columns: Theory and experimentsPacked distillation columns are usually designed on the basis of a sequential approach, in which first the Equilibrium Stage (EQ) model is used to quantify the separation effort before the required packing height is determined by HETP values. This approach is often sufficient for process design and proper sizing of the column. However, in certain cases the combination of the EQ model and HETP values results in an inappropriate column design. The design accuracy can be improved using a rate-based (RB) approach. Unfortunately, there is no reliable heuristic available to decide which modeling approach should be chosen. Therefore, the current study investigates the need for rate-based modeling in distillation processes by systematically evaluating the differences between EQ and RB composition trajectories. A criterion based on the Euclidean distance is proposed to evaluate the differences between the EQ and RB trajectories. Then, by means of a selectivity analysis basic criteria for model discrimination are derived and validated experimentally. Generally, for wide boiling mixtures the differences between the EQ and RB trajectories are the most distinct. The differences in the trajectories can be further increased or decreased by component specific mass transfer.Publicationtype: Journal Article211