Kai Sundmacher

Max Planck Institute for Dynamics of Complex Technical Systems | MPI · Department Process Systems Engineering (PSE)

Hydrogen crossover in polymer electrolyte membrane electrolysis cells is important concerning faradaic efficiency, flammability hazards, and degradation phenomena. In recent years, steady-state H2-in-O2 measurements have demonstrated that the hydrogen crossover increases with current density, due to mass transport limitations in the cathode catalys...

Lignocellulose is one of the most promising renewable bioresources for the production of chemicals. For sustainable and competitive biorefineries, effective valorization of all biomass fractions is crucial. However, current efforts in lignocellulose fractionation are limited by the use of either toxic or suboptimal solvents that do not always allow...

The accurate prediction of physicochemical properties of chemical compounds in mixtures (such as the activity coefficient at infinite dilution $\gamma_{ij}^\infty$) is essential for developing novel and more sustainable chemical processes. In this work, we analyze the performance of previously-proposed GNN-based models for the prediction of $\gamma...

Catalyst research is concerned with synthesizing increasingly active materials, leading to safety issues at reactor scale, unless the reaction heat release is controllable. Computational studies predict, that core-shell pellets, with catalytically active core and inert shell, are beneficial for this purpose, compared to established concepts, such a...

Renewable methanol production is an important part of the energy transition of the chemical industry from fossil to renewable resources. This work presents the design of a methanol production from renewable energy only, using an extended optimization-based FluxMax approach. This linear programming design approach considers waste-heat utilization in...

Interpretable machine learning (ML) is applied to accelerate the discovery of promising metal–organic frameworks (MOFs) for the selective separation of ethane (C2H6) and ethylene (C2H4). Based on molecular simulation data, ML models are first trained and tested to classify MOFs into C2H4-selective and C2H6-selective categories using different types...

Although eutectic solvents (ES), also widely termed as deep eutectic solvents (DES), have attracted significant interest in various chemical processes, the rational design of them remains challenging due to the difficulty in estimating eutectic formation. In this work, the regular solution theory (RST) and quantitative structure-activity relationsh...

Understanding the influence of dynamic and stationary polarization on the deactivation of state-of-the-art IrOx catalysts is imperative for the design and operation of robust and efficient proton exchange membrane water electrolyzers. In this work, the deactivation and activity regeneration of a commercial IrOx catalyst were investigated under pote...

Adsorption is widely used for gas separation and storage. Its performance relies heavily on the selection of suitable adsorbents. In this work, a data-driven neural recommender system is developed for a preliminary adsorbent screening. Over 32,000 single-component isotherms are retrieved from the NIST isotherm database. After a series of filtering...

A two‐step integrated metal‐organic framework (MOF) and pressure/vacuum swing adsorption (P/VSA) process design has been recently established for gas separation. In the first step, selected MOF descriptors and process operating conditions are simultaneously optimized to maximize the process performance. Based on the obtained results, the second ste...

Significance The discovery that amphiphilic polymers, similar to phospholipids, can self-assemble to vesicles has inspired numerous applications. For instance, these polymersomes are employed for drug delivery due to their increased chemical and mechanical stability. These polymers can be also mixed with lipids to form the so-called hybrid membrane...

Cylindrical, cm‐sized monolithic Al 2 O 3 xerogels with hierarchical meso‑/macropore system were prepared by sol‐gel synthesis. The influence of both solvent exchange and drying on monolith stability and the resulting pore system was studied following mass and volume of the monolith as well as by porosimetry and electron microscopy. Crack‐free dryi...

A two-step integrated MOF and pressure/vacuum swing adsorption (P/VSA) process design has been recently established for gas separation. In the first step, selected MOF descriptors and process operating conditions are simultaneously optimized to maximize the process performance. Based on the obtained results, the second step (i.e., MOF matching) is...

Identification of high-performing sorbent materials is the key step in developing energy-efficient adsorptive separation processes for ethylene production. In this work, a computational screening of metal-organic frameworks (MOFs) for the purification of ethylene from the ternary ethane/ethylene/acetylene mixture under thermodynamic equilibrium con...

Back Cover: In article number 2100712 by Ivan Ivanov and co‐workers, a functionalized dimethicone, commercially used as emulsifier in cosmetics, self‐assembles into vesicles and even provides a suitable environment for membrane proteins. Upon vigorous agitation in the presence of physiological concentrations of salt, these vesicles continuously fus...

There is considerable motivation in the catalysis community and chemical industry to envision a future where rational catalyst design and targeted chemical process optimization become standard. Achieving this goal for heterogeneous catalysis requires a cultural shift centered around effective research data management. The core elements of modern ca...

A novel integrated machine learning (ML) framework, consisting of structure decomposition, feature integration and predictive modeling, is proposed to correlate MOF structures with gas adsorption capacities. First, metal nodes, organic linkers, and underlying topologies are identified from MOF structures. Numerical features of the organic linker ar...

The use of predictive methods for physicochemical properties is of special interest given the difficulties involved in the experimental determination of large chemical spaces. In this work, we focus on...

Fixed-bed reactors employed within Power-to-X technologies are expected to be subject to volatile process feeds, in order to minimize intermediate buffer or storage systems. In this context, catalyst particles with an inert shell have proven suitable to prevent reactor runaway and severe temperature excursion at various loads and during load-change...

Gas separation accounts for a major production cost in chemical industries. So far, pressure swing adsorption (PSA) has been widely used for gas separation applications such as H2 purification and CO2 capture. For PSA processes, the adsorption efficiency is greatly affected by the selected adsorbent and process operating conditions. Over the past d...

Metal-organic frameworks (MOFs) are recognized as promising materials for gas storage and separation due to their structural diversity, high porosity, and tailorable functionality. Considering the large number of possible MOFs, an integrated machine learning framework is proposed to discover promising candidates with desirable adsorption properties...

In this contribution, we propose a new CAMD approach for solvent design by combining machine learning with deterministic optimization. Variational autoencoder (VAE), a powerful generative machine learning method, is used to transfer a molecular structure into a continuous latent vector with an encoder and to convert the latent vector back to the mo...

Considering the critical roles of hydrogen in energy transition and the renewable character of biogas, an integrated process linking ionic liquid (IL) based biogas upgrading and thermal plasma (TP) assisted hydrogen production is conceptually proposed and studied from the process intensification point of view. To select a practically suitable IL ab...

An integrated metal‐organic framework (MOF) and pressure/vacuum swing adsorption (P/VSA) process design framework is presented for gas separation. It consists of two steps: adsorbent descriptor optimization and MOF matching. In the first step, MOFs are represented as a large set of chemical and geometric descriptors from which the most influential...

Giant unilamellar vesicles serve as membrane models and primitive mockups of natural cells. With respect to the latter use, amphiphilic polymers can be used to replace phospholipids in order to introduce certain favorable properties, ultimately allowing for the creation of truly synthetic cells. These new properties also enable the employment of ne...

Although it is well known that solvent is one of the most important decision variables in liquid-liquid extraction processes, many previous studies focused on a specific class of solvents while neglecting alternatives. This work presents a comparative screening of two types of most extensively studied solvents, i.e., organic solvents (OS) and ionic...

A chemical plant layout for the production of syngas from renewable power, H 2 O and biogas, is presented to ensure a steady productivity of syngas with a constant H 2 -to-CO ratio under time-dependent electricity provision. An electrolyzer supplies H 2 to the reverse water-gas shift reactor. The system compensates for a drop in electricity supply...

The use of hydrogen as clean energy has attracted significant attention because conventional industrial hydrogen production processes show negative environmental impact, require intensive energy, and/or are dependent on natural gas. The main objective of this study is to develop an innovative and environment-friendly hydrogen production process uti...

A variety of artificial cells springs from the functionalization of liposomes with proteins. However, these models suffer from low durability without repair and replenishment mechanisms, which can be partly addressed by replacing the lipids with polymers. Yet natural membranes are also dynamically remodeled in multiple cellular processes. Here, we...

An integrated metal-organic framework (MOF) and pressure/vacuum swing adsorption (P/VSA) process design framework is presented for gas separation. It consists of two steps: descriptor optimization and MOF matching. In the first step, MOFs are represented as a large set of chemical and geometric descriptors from which the most influential ones are s...

The bottom-up approach in synthetic biology aims to create molecular ensembles that reproduce the organization and functions of living organisms and strives to integrate them in a modular and hierarchical fashion toward the basic unit of life—the cell—and beyond. This young field stands on the shoulders of fundamental research in molecular biology...

This paper reports the results of supercritical carbon dioxide (scCO2) extraction of β-carotene from Dunaliella salina as potential alternative to conventional organic solvent extraction. In pilot-scale scCO2 experiments, the pressure, temperature, and co-solvent concentration were varied. The supercritical extraction at 500 bar, 70 °C, and 10 wt%...

Many research activities focus on load-flexible fixed-bed reactors in the context of Power-to-X concepts. One of the main issues is the occurrence of hazardous temperature excursions in steady state and during dynamic load changes. The dilution of the catalytically active fixed-bed with inert particles and the use of catalyst particles with active...

Concentration frequency response analysis (CFRA) applies partial pressure of a certain reactant and detects current or voltage response depending on the electric control applied. In this paper experimental and theoretical spectra of this novel frequency response analysis method of polymer electrolyte fuel cells are analyzed. It is shown that the dy...

A new method for integrated ionic liquid (IL) and absorption process design is proposed where a rigorous rate‐based process model is used to incorporate absorption thermodynamics and kinetics. Different types of models including group contribution models and thermodynamic models are employed to predict the process‐relevant physical, kinetic, and th...

The transfer of electrons across and along biological membranes drives the cellular energetics. In the context of artificial cells, it can be mimicked by minimal means, while using synthetic alternatives of the phospholipid bilayer and the electron-transducing proteins. Furthermore, the scaling up to biologically relevant and optically accessible d...

The world’s increasing population requires the process industry to produce food, fuels, chemicals, and consumer products in a more efficient and sustainable way. Functional process materials lie at the heart of this challenge. Traditionally, new advanced materials are found empirically or through trial-and-error approaches. As theoretical methods a...

Optimization of pressure swing adsorption (PSA) remains a challenging task, as these are periodic dynamic systems governed by nonlinear PDE systems. This study develops an optimization strategy that incorporates reduced PSA models and also samples information from a high-fidelity ’truth’ model. The reduced model is based on equilibrium theory and c...

Artificial systems capable of self-sustained movement with self-sufficient energy are of high interest with respect to the development of many challenging applications, including medical treatments, but also technical applications. The bottom-up assembly of such systems in the context of synthetic biology is still a challenging task. In this work,...

de Seit der Gründung der Otto‐von‐Guericke‐Universität Magdeburg (OVGU) wurde der Forschungsbereich Verfahrenstechnik dort stetig ausgebaut. Heute umfasst die Fakultät für Verfahrens‐ und Systemtechnik der OVGU die vier Institute Verfahrenstechnik, Chemie, Strömungstechnik und Thermodynamik sowie Apparate‐ und Umwelttechnik. In diesem Beitrag stell...

A novel benchmark superstructure is defined for the production of syngas from renewable energy, \(\mathrm {H_2}\), \(\mathrm {CO_2}\) and biogas. Fixed bed reactors (FBR) for the dry reforming (DR) or the reverse water gas shift (RWGS) are used to convert the reactants into raw syngas, which is then purified in a sequence of pressure and/or tempera...

For the ionic liquid (IL)‐solute systems of broad interest, a deep neural network based recommender system (RS) for predicting the infinite dilution activity coefficient (γ∞) is proposed and applied for a large extension of the UNIFAC model. In the RS, neural network entity embeddings are employed for mapping each IL and solute, and neural collabor...

With the increasing need to utilize carbon dioxide, fixed-bed reactors for catalytic hydrogenation will become a decisive element for modern chemicals and energy carrier production. In this context, the resilience and flexibility to changing operating conditions become major objectives for the design and operation of real industrial-scale reactors....

A new method for integrated ionic liquid (IL) and absorption process design is proposed where a rigorous rate-based process model is used to incorporate absorption thermodynamics and kinetics. Different types of models including group contribution models and thermodynamic models are employed to predict the process-relevant physical, kinetic, and th...

The electrolysis of HCl to form Cl2 is an integral part of the production of polycarbonates and polyurethanes. In recent years, the direct gas-phase electrolysis was shown to be significantly more efficient than the current state-of-the-art process based on the oxidation of hydrochloric acid. Still, three phenomena significantly limit the performan...

The selection of phase change material (PCM) is essential for the development of efficient thermal energy storage (TES) processes. Due to their benign properties, ionic liquids (ILs) have been demonstrated to be a new type of promising PCM. Unfortunately, there is a lack of systematic study on the optimal selection or molecular design of IL-PCMs fo...

The Numerical Matrices Methods (NMM) are assessed regarding their potential for reconstructing the topology and kinetics of biochemical reaction networks featuring increasing complexity, from a single-enzyme system to a three-enzyme cyclic network. The eventual goal is to use this analysis framework for synthetic in vitro enzymatic networks for whi...

The design of fixed-bed reactors has gained interest in the light of load-flexible operation. This is due to the expectation that some process feeds will be more volatile in the near future, for example, within the framework of the power-to-methane concept. In this regard, the application of an inert shell onto the catalyst particles has proven adv...

This work presents a computer-aided framework for the screening of deep eutectic solvent (DES) systems by using the α-tocopherol extraction from methylated oil deodorizer distillates (MODD) as an example of practical relevance. Taking advantage of the differences in the hydrogen bond donating abilities of α-tocopherol and methyllinoleate (model com...

The optimization of a controlled process in a simulation without access to the model itself is a common scenario and very relevant to many chemical engineering applications. A general approach is to apply a black-box optimization algorithm to a parameterized control scheme. The success then depends on the quality of the parametrization that should...

Microalgae have enormous potential as producers of fine and platform chemicals. However, sophisticated, energy-efficient separation strategies for fractionating the algal biomass are still under research and no economically viable biorefinery...

Solvents define pivotal properties for chemical processing and chemical reactions, and can be as game-changing as catalysts. A solvent can be the key to a good chemical process, rather than being just an asset and a reaction space. It determines the solubility, meaning the concentration at which reactants can be processed, determines the stability...

CO2 methanation is often performed on Ni/Al2O3 catalysts, which can suffer from mass transport limitations and, therefore, decreased efficiency. Here we show the application of a hierarchically porous Ni/Al2O3 catalyst for methanation of CO2. The material has a well-defined and connected meso- and macropore structure with a total porosity of 78%. T...

Understanding degradation phenomena of polymer electrolyte water electrolyzers operating under dynamic conditions is imperative for developing and implementing efficient and reliable means of energy storage from fluctuating and intermittent renewable energy sources. Herein, a commercial membrane electrode assembly with an amorphous IrOx anode is su...

The selection of phase change material (PCM) plays an important role in developing high-efficient thermal energy storage (TES) processes. Ionic liquids (ILs) or organic salts are thermally stable, non-volatile, and non-flammable. Importantly, researchers have proved that some ILs possess higher latent heat of fusion than conventional PCMs. Despite...

Several experimental techniques involving dynamic electrical variables are used to study the complex behaviour of polymer electrolyte membrane fuel cells in order to improve performance and durability. Among them, electrochemical impedance spectroscopy (EIS) is one of the most employed methods. Like any frequency response analysis (FRA) methodology...

For the design of eutectic solvents (ESs, usually also known as deep eutectic solvents), the prediction of the solid-liquid equilibria (SLE) between candidate components is of primary relevance. In the present work, the SLE prediction of binary eutectic solvent systems by the COSMO-RS model is systematically evaluated, thereby examining the applica...

A hydroformylation process of long-chain olefines is investigated. In an attempt to replace an established, toxic solvent used in this process, a computer aided molecular design approach based on group contribution methods is used to predict the solvent properties, as well as the liquid-liquid equilibrium of the mixture and environment, health and...

Steam methane reforming processes represent the economically most competitive processes for the production of synthesis gas and hydrogen despite their high energy costs. Although there is a strong need for highly resource-efficient production, literature on the optimal design of reformers remains scarce due to the inherently high complexity of thes...

Within the context of energy transition scenarios toward renewable resources, superstructure optimization is implemented for the synthesis of sustainable and efficient Power-to-Syngas processes. A large number of reactors (reverse water-gas-shift, steam reforming, dry reforming, tri-reforming, methane partial oxidation reactor, and water electrolyz...

A superstructure optimization approach to power-to-methane process design that includes heat integration is presented. Carbon dioxide from biogas plants is considered as carbon source. The superstructure includes 13 alternative process technologies in seven layers for power-to-methane processes at their current stage of development. For different s...

Understanding the pathways of oxygen evolution reaction (OER) and the mechanisms of catalyst degradation is of essential importance for developing efficient and stable OER catalysts. Experimentally, a close coupling between OER and catalyst dissolution on metal oxides is reported. In this work, it is analysed how the microkinetic network structure...

The kinetic gas theory, in particular the equations of Chapman and Enskog, proved to be good and widely applicable approximations for modeling transport properties like diffusion coefficients, viscosities and thermal conductivities. However, these equations rely on at least the Lennard-Jones parameters and for polar gases also the dipole moment. In...

Artificial systems capable of self-sustained movement with self-sufficient energy are of high interest with respect to the development of many challenging applications including medical treatments but also technical applications. The bottom-up assembly of such systems in the context of synthetic biology is still a challenging task. In this work, we...