Title: Molecular Mechanisms of Adsorption of Polar Molecules in Porous Materials for Energy Storage Applications

Speaker: Vicent Luna (TU/e MSM group)
Time: Nov. 24, 2022, 10:00–11:00
Location: TU/e Disruptor 0.30 and online (MS Teams)

Abstract | Adsorption of small polar molecules, such as ammonia, light alcohols, or water in porous materials is receiving significant attention because these compounds are used in a wide range of applications. Despite the differences between these polar molar molecules, they have a common application; they are used as refrigerants for energy-related applications. In recent years, thermal energy storage has become a key technology for improving the efficiency and sustainability of heat storage applications to reduce carbon dioxide emissions. These systems use the energetic exchange during the adsorption/desorption of working fluids in porous materials. Therefore, understanding the adsorption mechanisms is crucial to improve the performance of energy storage devices.

In this work, I review the adsorption of the above-mentioned molecules in various porous materials from a molecular simulation perspective. As adsorbents, we studied zeolites, metal-organic frameworks, activated carbons, and mesoporous carbon matrices. In this regard, we considered challenging mechanisms such as 1) a complex network of cage connections of the porous adsorbent, 2) the effect of framework flexibility in the adsorption, 3) the role of functional forms on the framework surface or impurities, and 4) the modeling of non-crystalline materials. We combined molecular dynamics, Monte Carlo, and energy minimization simulations to describe the mentioned mechanisms at the molecular level. The results were tested and validated against experiments, thus providing insights that are challenging to find in laboratory measurements.

The CCER seminars are aimed at researchers interested in computational approaches to (energy) research. The seminar is small-scale, typically 15 participants, and interactive, offering lots of room for discussion. If you would like to attend, just This email address is being protected from spambots. You need JavaScript enabled to view it. so as to receive the MS Teams meeting link.

Title: Exchanging replicas with unequal cost, infinitely and permanently

Speaker: Titus van Erp (NTNU)
Time: Nov. 10, 2022, 10:00–11:00
Authors: Sander Roet, Daniel T. Zhang, and Titus S. van Erp
Location: TU/e Flux 1.124 and online (MS Teams)

Abstract | We developed a replica exchange method that is effectively parallelizable even if the computational cost of the Monte Carlo moves in the parallel replicas are considerably different, for instance, because the replicas run on different type of processor units or because of the algorithmic complexity. To prove detailed-balance, we make a paradigm shift from the common conceptual viewpoint in which the set of parallel replicas represents a high-dimensional superstate, to an ensemble based criterion in which the other ensembles represent an environment that might or might not participate in the Monte Carlo move. In addition, based on a recent algorithm for computing permanents, we effectively increase the exchange rate to infinite without the steep factorial scaling as function of the number of replicas. We illustrate the effectiveness of the replica exchange methodology by combining it with a quantitative path sampling method, replica exchange transition interface sampling (RETIS), in which the costs for a Monte Carlo step can vary enormously as paths in a RETIS algorithm do not have the same length and the average path lengths tend to vary considerably for the different path ensembles that run in parallel. This combination, coined ∞RETIS, was tested on three model systems.

The CCER seminars are aimed at researchers interested in computational approaches to (energy) research. The seminar is small-scale, typically 15 participants, and interactive, offering lots of room for discussion. If you would like to attend, just This email address is being protected from spambots. You need JavaScript enabled to view it. so as to receive the MS Teams meeting link.

Title: Multi-scale Modeling of Adsorptive Separation Devices

Speaker: David Dubbeldam (UvA)
Time: Oct. 27, 2022, 10:00–11:00
Location: TU/e Flux 1.124 and online (MS Teams)

Abstract
The separation of mixtures, including enrichment, concentration, purification, refining and isolation are of extreme importance to chemists and chemical engineers. Pressure swing adsorption (PSA) is a non-cryogenic gas separation technology that achieves very high purity. Generally, the PSA process uses two or more adsorbent columns to avoid system downtime during the adsorption and desorption processes. The frequency of regeneration is an important parameter in the efficiency of the PSA unit and is a function of the adsorbent material, the selectivity, and operating conditions. Using molecular simulations, we efficiency screen possible nanoporous materials for their performance in PSA processes.

Using several levels of modeling (i.e., multi-scale modeling), we can accurately evaluate the efficiency of adsorptive separations. Using classical simulation techniques (i.e., Monte Carlo), we can compute adsorption isotherms for the crystalline nanoporous materials used in the adsorbent column. The next step/level, is to fit (using Genetic Algorithms), an isotherm model to the isotherm data. The isotherm model, and a model for the mixture adsorption, go into the higher-level modeling of the breakthrough apparatus. Hence, I will cover a wide variety of the techniques used at each level, and how they connect to each other. I will demo the modeling using computer codes.

The CCER seminars are aimed at researchers interested in computational approaches to (energy) research. The seminar is small-scale, typically 15 participants, and interactive, offering lots of room for discussion. If you would like to attend, just This email address is being protected from spambots. You need JavaScript enabled to view it. so as to receive the MS Teams meeting link.

Title: Multiscale modelling of the nanoparticle-support interfacial perimeter in heterogeneous catalysis

Speaker: Ivo Filot (TU/e, Inorganic Materials & Catalysis group )
Time: Oct. 13, 2022, 10:00–11:00
Location: TU/e Flux 3.265 and online (MS Teams)

Metallic nanoparticles stabilized on an inorganic support are the most common class of heterogeneous catalysts. The role of the support is much broader than just to stabilize and disperse the catalyst nanoparticles. The support material can modulate the nanoparticle surface morphology and induces formation of active sites. On an atomistic level, the support affects the electronic structure of the active sites involved in the chemical transformation or even hosts unique active sites by itself offering alternative reaction pathways. An ability to tune the interfacial parameter between the support and the nanoparticle is thus an attractive design feature to optimize the catalyst activity and selectivity. Despite numerous efforts, a detailed understanding of the nanoparticle-support interplay is however lacking as nanoparticle/support-interfacial sites are incredibly difficult to characterize due to the limited spatiotemporal resolution of common experimental techniques.

In this presentation, I will show how multiscale computational modelling can be used to describe the complex interplay between the catalyst nanoparticles and their support material. I will explicitly demonstrate this for two important catalytic reactions: the conversion of CO2 to methanol over Ni/In2O3 and the activation of CO over supported Co nanoparticles. Employing modern electronic structure characterization techniques such as Crystal Hamilton Orbital Population analysis, I will explain how a support material can modulate the barriers of elementary reaction steps, which serves as a powerful design feature to optimize existing catalytic materials. Furthermore, I will showcase that non-innocent support materials, e.g. reducible oxides that can form oxygen vacancies, can be involved in synergetic reaction events which lead under the right circumstances to an enhancement of the catalyst selectivity. Using microkinetic simulations and post-simulation sensitivity analysis, we can characterize which elementary reaction steps are most influential to the macroscopically observed catalytic activity. The insights gained offer opportunities to guide the design of novel improved catalyst formulations.

221013 ccer seminar ivo filot picture1 

The CCER seminars are aimed at researchers interested in computational approaches to (energy) research. The seminar is small-scale, typically 15 participants, and interactive, offering lots of room for discussion. If you would like to attend, just This email address is being protected from spambots. You need JavaScript enabled to view it. so as to receive the MS Teams meeting link.