Publication in Energy Conversion and Management (24 June 2022)

Natural iron ores for large-scale thermochemical hydrogen and energy storage

S. Bock, M. Pauritsch, S. Lux, V. Hacker

The potential of the extremely low-cost alternative of energy and hydrogen storage in the form of natural iron ores has been extensively studied and evaluated both theoretically and experimentally.
Natural iron ores as storage materials are advantageous because the specific costs are an order of magnitude lower compared to synthetic iron oxide-based materials.
For this purpose, regionally available siderite, a carbonate-bearing iron ore, with low reaction temperatures and high storage capacity was investigated in comparison with commercial iron ores such as ilmenite and others.
Specific storage costs are 80-150 $/MWh of hydrogen stored, based on experimental in situ tests. The experimentally determined volumetric energy storage capacity for the bulk material was 1.7 and 1.8 MWh/m3 for hydrogen and heat release, respectively. The raw siderite ore was stable in in situ life tests for 50 consecutive cycles at operating temperatures of 500-600 °C.
The low material price combined with reasonable storage capacity results in very low specific storage costs of 0.075 $/kWh and 0.08-0.15 $/kWh for heat and hydrogen storage, respectively.


  • Natural carbonate ores are promising for thermochemical hydrogen and energy storage.
  • Cheap, abundant and environmentally friendly storage material.
  • Large-scale energy storage in TWh-range.
  • Thorough experimental analysis as basis for system design.

Energy Conversion and Management, Elsevier 2022

Publication in Chemical Engineering Research and Design (14 June 2022)

Deep eutectic solvents as entrainers in extractive distillation - A review

Maximilian Neubauer, Thomas Wallek, Susanne Lux

One of the most common techniques for separating azeotropes and close-boiling mixtures is extractive distillation, where the relative volatility of the components to be separated is altered by adding an entrainer. In recent years, deep eutectic solvents have emerged as a new class of entrainers in extractive distillation. Similar to the related class of ionic liquids, deep eutectic solvents combine the high separation capability of solid salts with the simple handling of liquids, additionally exhibiting low to negligible vapour pressures and non-flammability. Compared to ionic liquids, deep eutectic solvents offer advantages in terms of toxicity issues but also solvent costs. In this review, the current state of research regarding deep eutectic solvents in extractive distillation spanning from vapour-liquid- equilibrium measurements and thermodynamic modelling of the corresponding systems to general entrainer feasibility considerations and process simulations is presented and critically evaluated. Additionally, future prospects and comments on unresolved issues are provided.

Chemical Engineering Research and Design 184 (2022) 402-418

Sustainability Award 2022 (13 June 2022)

For the project ‘On-site Biogas Utilization for Decentralized Hydrogen Production (Biogas2H2)’, the project team was awarded the Sustainability Award 2022, field of action Regional Cooperation, 3rd place by the Federal Ministry of Education, Science and Research (BMBWF - BM Polaschek) and the Federal Minister for Climate Action, Environment, Energy, Mobility, Innovation and Technology (BMK - BM Gewessler). on June 13, 2022 at the Technical Museum Vienna.


Mondi/Heinzel/SAPPI award in the category Pulping Process (24 May 2022)

Thomas Pichler received for his PhD thesis with the title “ Processing of Lignin: Development of Precipitation and Modification Processes” the Mondi/Heinzel/SAPPI award in the category Pulping Process (including utilization of side streams from the pulping process). Thomas Pichler developed basics for the absorption of CO2 in NaOH, which was the basis for the development of an air lift reactor for lignin precipitation and isolation. He received the price during the Pulp& Biorefinery conference on 24th of May 2022 in Graz.

Long Night of Research (20 May 2022)

Station: Hydrogen - Drive of the future?

During the Long Night of Research at Graz University of Technology, the research group of fuel cells at the Institute of Chemical Engineering and Environmental Technology, headed by Prof. Viktor Hacker, gave insights into the topics of hydrogen and fuel cells as part of the ongoing international networking project H2GreenTECH.

Using the demonstration model built as part of the H2GreenTECH project, the environmentally friendly production, storage and use of hydrogen as a fuel instead of fossil fuels was vividly explained to many visitors. The generation of renewable energy by photovoltaic cells and its further use for the production of green hydrogen by an electrolyser was demonstrated. Hydrogen storage and easy energy recovery (whenever needed) through a fuel cell were also demonstrated. By showing the demonstration model, young visitors were also able to get excited about hydrogen technology. Through the distribution of promotional materials (bags, mugs, notebooks), the awareness gained about renewable energy and the environment will be remembered by the visitors for a long time through daily use.

Information table on the energy cycle of hydrogen with the CEET team (from left to right: Mario Kircher, Prof. Viktor Hacker, Michaela Roschger, Sigrid Wolf, Karin Malli) at the Long Night of Research 2022 at TU Graz. Presentation of the demo test rig (right).


Article in Chemie Ingenieur Technik (19 May 2022)

Application of the TRIZ Contradictory Matrix to Foster Innovation for Sustainable Chemical Engineering

Susanne Lux

This work demonstrates how to apply the Theory of Inventive Problem Solving (Russian acronym TRIZ) on two industrial-scale case studies. The first case study addresses processing of mineral metal carbonates, which is characterized by high CO2 emissions and high energy demand. As solver strategy a novel reductive pathway is suggested. The second case study refers to biobased industrial processes, which discharge aqueous effluents with unexploited carboxylic acid loads. Reactive separations are proposed to isolate the carboxylic acids. In both solver strategies, chemical reactions adopt a central role.

Chemie Ingenieur Technik (2022)

Publication in Computers and Chemical Engineering (26 April 2022)

Case-study of a flowsheet simulation using deep-learning process models for multi-objective optimization of petrochemical production plants

Fabian Zapf, Thomas Wallek

This work demonstrates a case-study to create machine-learning based process models from process data, which are connected into an overall process flowsheet and provide a high level of numerical stability for further multi-objective optimization. The used models are black-box and gray-box models, which are further compared to the proven LP approach. The proposed methodology is demonstrated using real- world measurement data from a refinery, involving a distillation unit, a hydrotreater, a reformer and an ethylene plant. The developed unit models are connected into an overall process flowsheet, which is solved by a sequential-modular approach and optimized in view of maximizing production margin and minimizing CO2 -emissions. This work points out that the combination of engineering knowledge with data-driven techniques enables the incorporation of indirect information for process units, e.g., the crude oil composition vector for downstream units, leveraging the prediction performance of the unit models, compared to models not involving this information.

Computers and Chemical Engineering 162 (2022) 107823


Article in Chemie Ingenieur Technik (01 April 2022)

Direct Reduction of Siderite Ore Combined with Catalytic CO/CO2 Hydrogenation to Methane and Methanol: A Technology Concept

Sascha Kleiber, Astrid Loder, Matthäus Siebenhofer, Andreas Böhm, Susanne Lux

Industrial CO2 emission mitigation necessitates holistic technology concepts; especially in high-emission industrial sectors like the iron and steel industry. A novel direct reduction technology with hydrogen reduces CO2 emissions in iron production from siderite ore by more than 60 %. Subsequent valorization of the process gas, consisting of unconverted hydrogen, carbon monoxide, and CO2, by catalytic hydrogenation to methane and methanol completes the technology concept. This route gives access to CO2 emission-lean iron production from siderite ore, fossil-free methane and methanol synthesis, and thus, improved energy density of the energy carrier hydrogen.

Chem. Ing. Tech.2022,94, No. 5, 701–711

Article in Chemie Ingenieur Technik (23 March 2022)

Esterification of Acetic Acid with Methanol and Simultaneous Product Isolation by Liquid-Liquid Extraction in a Taylor-Couette Disc Contactor

Georg Rudelstorfer, Maximilian Neubauer, Matthäus Siebenhofer, Susanne Lux and Annika Grafschafter

Isolation of carboxylic acids from dilute aqueous effluents can be achieved by the combination of liquid-phase catalyzed reaction with liquid-liquid extraction. Exemplarily the heterogeneously catalyzed esterification of acetic acid with methanol, accelerated with a cation-exchange resin and simultaneous transfer of the product methyl acetate into the solvent ShellSol T, was successfully performed in a Taylor-Couette disc contactor (TCDC) in batch operation mode. Stable three-phase flow (liquid-liquid-solid) was confirmed in lab scale. The conversion of acetic acid in a TCDC operated in batch mode compares well with conversion in a batch reactor.

ChemieIngenieurTechnik, Volume94, Issue5, Special Issue: Chemische Reaktionstechnik, May 2022, 671-680

“Interactive Thermodynamics” – a new TEL Marketplace project @ CEET

One of the flagship projects of the "Digital TU Graz" is the participatory innovation program "Digital TU Graz Marketplace", which transfers methodical and technical innovations in the form of funded pilot projects to university practice in the long term.

Sascha Kleiber, Michael Haring and Thomas Wallek are one of the winning teams in the Digital TU Graz Marketplace 2022 competition. Beginning April 1, 2022, the three will implement a digital innovation project in teaching aimed at new methods of imparting knowledge in courses:

  • The exercise course "Chemical thermodynamics I", which is part of one BSc and three MSc programs, is currently held in a traditional way at the blackboard
  • The project idea is to design the exercises as interactive Wolfram Mathematica Notebooks and to make them available to the students via the TeachCenter
  • For a limited time, these notebooks will also be accessible in the Wolfram Cloud so that calculations can be conducted directly in this cloud, even via mobile devices
  • The intention is to make inherently dry course content more accessible to students through animations of equations and manipulability of diagrams, as well as to create a new user experience

For further information, including a pitch video, click here < > or follow the QR-Code:

RSE-SEE8. The 8th Regional Symposium on Electrochemistry for Southeast Europe will be organized by us at TU Graz from 11-15 July 2022.

ESAT 2022. We are proud to announce that the 32nd European Symposium on Applied Thermodynamics will be held in Graz from 17-20 July 2022.

Summer School on Fuel Cells & Hydrogen. We are co-organizers of the next summer school at Yokohama National University, Japan from 29 Aug – 3 Sept 2022. Join us!

Publication in Applied Electrochemistry (04 February 2022)

Multi-walled carbon nanotube-supported Ni@Pd core–shell electrocatalyst for direct formate fuel cells

S. Abrari, V. Daneshvari‑Esfahlan, M. G. Hosseini, R. Mahmoodi, V. Hacker

In the present work, Ni@Pd core–shell nanoparticles are successfully deposited on multi-walled carbon nanotubes as support and investigated their performance towards formate oxidation reaction. The structural features of the catalyst are characterized by scanning electron microscopy, transmission electron microscopy, and X-ray photoelectron spectroscopy. According to the results, the size of the Ni@Pd core–shell nanoparticles is 5–10 nm and the nanoparticles are uniformly deposited on the multi-walled carbon nanotubes. The performance of the synthesized electrocatalysts for the formate oxidation reaction is investigated by cyclic voltammetry, chronoamperometry and electrochemical impedance spectroscopy as well as their comparison with Ni–Pd alloy nanoparticles on multi-walled carbon nanotubes. The results indicated that the Ni@Pd core–shell nanoparticles on multi-walled carbon nanotubes show higher electrocatalytic activity and stability than the Ni–Pd alloy nanoparticles on multi-walled carbon nanotubes against formate electrooxidation reaction. Moreover, the efficiency of synthesized anodic electrocatalysts is evaluated in a direct sodium formate-hydrogen peroxide fuel cell by employing a Pt/carbon as cathode (0.5 mg cm−2) and Ni@Pd core–shell nanoparticles on multi-walled carbon nanotubes as anode (1 mg cm−2). A maximum power density of 45.56 mW cm−2 at 25 °C is achieved for this measurement.

Journal of Applied Electrochemistry, Springer 2022

Publication in Separation and Purification Technology (1 February 2022)

Reactive extraction of lactic acid from sweet sorghum silage press juice

P.Demmelmayer, M. Kienberger

Fermentation of residues or side streams can be used to produce valuable products, such as carboxylic acids. Reactive solvent extraction is widely studied as isolation method for lactic acid from fermentation broths. Here, we investigate the reactive extraction of lactic acid from sweet sorghum silage press juice using different extractants, modifiers, and diluents. Besides a high extraction efficiency, a low crud formation with this highly complex raw material is targeted. Depending on the solvent phase composition, an extraction efficiency of up to 41.1 % was reached using DOA/ALIQ:1–octanol:n–nonane. The crud layer was highly influenced by the applied diluent and amounted to 2.6–42.3 vol% of the total mixture volume. The back-extraction experiments showed, that up to 98.2 % of lactic acid were recovered. Summarizing, the results show that reactive solvent extraction of lactic acid is applicable to highly complex process streams, and crud formation can be reduced by adjusting the solvent phase composition.

Separation and Purification Technology, Volume 282, Part B, 1 February 2022, 120090

Summary report of Topical Meeting on Fuel Cells (10 December 2021)

Topical Meeting of the IEA AFC TCP on Potential for cost reduction and performance improvement for PEMFC at component and system level

Viktor Hacker & D.J. Liu

On 10/11 November 2021, the Topical Meeting on Potential for cost reduction and performance improvement for PEMFC at component and system level took place at Graz University of Technology. Due to the prevailing Corona situation at the time, the event was geared largely towards online participation, but (additional) personal attendance was also possible. A video stream of the event and interactive discussion of questions, both via chat and directly, allowed for a lively meeting in the auditorium of Graz University of Technology and online.

Event page

Summary report

Publication in RSC Advances (8 December 2021)

Cobalt-modified palladium nanocatalyst on nitrogen-doped reduced graphene oxide for direct hydrazine fuel cell

M.G. Hosseini, V. Daneshvari-Esfahlan, S. Wolf & V. Hacker

Nitrogen-doped reduced graphene oxide-supported palladium–cobalt nanoparticles (PdCo NPs/NrGO NSs) are synthesized and used as a high-performance and low-cost anodic catalyst for direct hydrazine–hydrogen peroxide fuel cells. The SEM and TEM images of PdCo NPs/NrGO NSs show the uniform metal nanoparticle distribution on the NrGO NSs. The reduction of the oxygen functional groups and the doping of the nitrogen atoms in the GO framework are confirmed by FT-IR and XRD spectroscopic studies. The Pd catalysts modified by Co exhibit a higher catalytic activity, lower onset potential, better durability, and lower impedance values than unmodified Pd catalysts for the electro-oxidation of hydrazine. The kinetic studies show a first-order reaction with an activation energy of 12.51 kJ mol-1. A direct hydrazine–hydrogen peroxide fuel cell with PdCo NPs/NrGO NSs as anode and Pt/C as cathode provides an open circuit voltage of 1.76 V and a maximum power density of 148.58 mW cm-2 at 60 °C, indicating that the PdCo NPs/NrGO NSs are an economical, high performance and reliable anode catalyst for the direct hydrazine–hydrogen peroxide fuel cell.

RSC Adv., 2021, 11, 39223