Principal investigator: Dr. Matej Huš
The project is at the crossroads of biomass utilization (produce glucaric acid) and method development (multiscale modelling). Glucaric acid is an important platform chemical, being produced in an environmentally problematic (toxic chemicals) and dangerous way. In this project, we will study and develop (theoretically and experimentally) a green synthesis pathway to use selective oxidation to produce glucaric acid from waste biomass, which is Slovenia’s most abundant and not fully exploited natural resource. To achieve this goal, modelling at different length and time scales will be performed and ultimately coupled by a novel multiscale modelling methodology and catalytic experiments. Based on calculations, novel catalyst formulations will be synthesized and tested.
Glucaric acid is one of the most important dicarboxylic acids, yet still mostly produced in a dangerously exothermic process with nitric acid, bleaching agents, emitting various nitrogen oxides. Catalytic production of glucaric acid is therefore being intensively studied but the process is plagued by poor selectivity and low yields. Most of research has focused on trialand- error testing of catalysts. Usually, only model compounds are investigated. This results in a fragmented understanding of the reaction mechanism and catalysts, yielding kinetic parameters for a narrow range of conditions on specific catalysts.
Multiscale modelling is becoming the most important technique in catalyst design and process optimization as it allows us to “look” at the reaction on different scales. While individual methods for describing reactions at different scales are relatively well developed, a comprehensive multiscale methodology for coupling them is lacking. A robust and versatile method for bottom-up multiscale modelling, starting from quantum chemistry calculations and concluding with a realistic description of the reactor, remains desired.
The project will solve these shortcomings by studying this reaction to predict and prepare better catalysts and operating conditions, and to further the development of multiscale modelling. First, a thorough catalyst screening for selective oxidation of model compounds will be performed. Using quantum chemistry calculations, prospective metals (noble metals, rare earths) will be evaluated for partial reactions (the desired and competing ones). Structure-activity relations will be determined to predict the activity of alloys. For the most promising catalysts and alloys, a complete reaction pathway with all conceivable elementary steps will be modelled. Thus, conditions-independent first-principles kinetic parameters will be obtained, which is crucial for understanding the reaction mechanism.
Then, the most promising catalysts along with the benchmark one (Au/TiO2) will be synthesized, characterised and experimentally tested. This will serve as a validation of the theoretical modelling and provide experimental correlations between the catalyst structure and performance. Kinetic modelling will be performed on experimental and theoretical data. Pressure, temperature, reactant ratio and catalyst alloying will be varied to determine their effects and identify optimum conditions. A mean field model will be constructed to explicitly consider hydrodynamic conditions, transport phenomena, possible non-catalysed reactions, adsorption/desorption rates form and to solid-liquid interphases. Thus, a realistic description of the reaction under relevant conditions will be obtained through solving transient equations.
Lastly, the performance of a plug-flow reactor will be modelled. Using data from microkinetic modelling, a reactor filled with different catalyst particles (cubes, spheres, slabs, hollow cylinders) and with different loadings will be studied. The calculated space-time, superficial and average velocities, the required reactor length and porosity will be quantities of interest in the final step of multiscale modelling.
The project is co-financed by ARRS with 1.172 annual hours of price class C for a period of 3 years. Funding starts on November 1, 2021.
At the National Institute of Chemistry the project group includes:
Phase 1: Quantum level calculations (catalyst screening)
- Set-up and benchmark of the quantum methods used.
- Calculations of descriptors and structure-activity relations.
- Combinatorial evaluation of alloys.
- Restructuring, catalyst shape and surface stability.
- Thermodynamics and reaction mechanism.
- The effect of defects.
Phase 2: Meso-scale modelling (and structure conditions screening)
- A Kinetic Monte Carlo model of the reaction mechanism.
- Screening of the reaction conditions.
- Catalyst size and shape effect.
- Development of a kinetic and mass transfer model.
Phase 3: Catalyst synthesis and characterisation
- Catalyst synthesis.
- Characterisation of fresh and used catalysts.
Phase 4: Catalyst testing (experimental validation)
- Testing the most promising catalysts under reference conditions.
- Experimental optimisation of conditions for the best catalyst
Phase 5: Reactor description and process parameter optimisation ("bringing it all together")
- Reactor modelling.
- Process optimisation.
Phase 6: Dissemination and reporting.
No published papers from the project yet.