Projects / Programmes
Development of a new reactor concept for microkinetic studies and its use for selective oxidative dehydrogenation of alkanes and methane coupling
| Code |
Science |
Field |
Subfield |
| 2.02.04 |
Engineering sciences and technologies |
Chemical engineering |
Catalysis and reaction engineering |
| Code |
Science |
Field |
| T350 |
Technological sciences |
Chemical technology and engineering |
| Code |
Science |
Field |
| 2.04 |
Engineering and Technology |
Chemical engineering
|
reactor engineering, chemical engineering, propylene, boron nitride, multiscale modeling
Researchers (12)
Organisations (2)
Abstract
The near-future global shortage of propylene is causing the development of on-purpose propylene technologies. Oxidative propane dehydrogenation prevents coke deposition on account of the oxygen present, and since the reaction is exothermic, lower temperatures are required for the reaction, normally around 300 – 500 °C. Accordingly, potential savings due to energy consumption are estimated at 45% and catalyst regeneration is not required. However, after decades of research, propane dehydrogenation has not reached economic viability. Partial oxidations are extremely challenging, since the products are often more reactive than the substrate and over-oxidation takes place. The development of catalysts, which could minimize the over-oxidation of olefins to CO2, is crucial for the commercial development of the oxidative dehydrogenation process.
Recently, a new class of material has been discovered, which holds the potential to revolutionize the global market. The materials, based on boron nitride, are non-toxic and inexpensive, and do not contain precious metals. Boron nitrate has excellent structural and thermal stability under oxidative atmospheres: it possesses high in-plane mechanical strength and is chemically inert also at high temperatures.
Ab initio quantum chemical calculations utilizing the density functional theory (DFT) computational framework will be performed for the catalysts showing the most promising activity and selectivity. We will use the Quantum Espresso software, which implement high-precision DFT simulations in plane-wave formalism. Using DFT, we can explain the reaction mechanism and compare adsorption energies and barriers for rate-determining steps of oxidative dehydrogenation on the novel catalysts.
The elimination of mass transfer limitations will be crucial for optimal operation and for the determination of the intrinsic kinetics, which will allow for the development of the microkinetic model and for obtaining the kinetic parameters. For this study, a novel reactor concept will be developed. The novel reactor will be: the High Velocity Gradient Reactor (HVGR). The defining feature will be a rapid acceleration/deceleration rotating fixed-bed, which will be able to completely remove mass transfer limitations. By applying more intense acceleration/deceleration, it will be shown, how conversion will increase, until maximum conversion at no mass transfer limitations will be achieved. The reactor concept is crucial for the correct determination of the microkinetic mechanisms and reaction kinetics.
The most successful process will be modeled with an axial dispersion model acknowledging convection, diffusion, dispersion, and reaction, which govern the overall chemical conversion process. A microkinetic model will be developed considering the mechanisms determined by DFT and kinetic Monte Carlo calculations. An empirical reaction rate expression will also be determined through the rate determining steps of the microkinetic model, which will allow for extensive simulations at various operational parameters. The modeling will be performed in the high-level programming language Python using numerical and scientific modules. The finite difference method will be used for the discretization of the computational domain. More complex CFD modeling will be performed with OpenFOAM, in which case CFD simulations of the realistic bed will be made. The catalyst particles will be designed according to SEM images obtained.
The evaluation of the final results along with the economic balance will allow for the development of a business case scenario. The document will contain a preliminary analysis of the most adequate product-market fit. A technology and market insight is essential for successful revenue generation and the market size and dynamics is one of the most important characteristics. The identification and clarification of the market opportunity will be one of the vital goals of this project.
Significance for science
The proposed project has a multilayered contribution to the development of science. Firstly, it will contribute to the further development of on-purpose propane conversion technologies, which will be very important in the near future due to the projected global deficit. The new class of catalysts is still extremely unexplored, and the reaction mechanisms are not well understood. In the project, very precise kinetic measurements using the new reactor concept will be performed. The experiments will be supported by microkinetic DFT and Kinetic Monte Carlo simulations, which will be essential for obtaining an understanding the reaction pathways. Such calculations today are state-of-the-art of the available knowledge. Simulations that will be performed with computational fluid dynamics (CFD) will precisely describe the realistic system of the packed-bed reactor, by calculating the flow and concentration profiles of all the components, taking into account the realistic packing with realistic particles. Combining CFD simulations and micro-kinetics is very scarce in the available literature.
The new reactor concept, which will be designed and constructed, will by itself be a great innovation and will be the first prototype of this kind. The description of its operation will definitely be of great interest to the chemical engineering society. The expected improved performance, under conditions without mass transfer resistance, has the potential to become a standard for the determination of chemical reaction kinetics.
Significance for the country
The proposed project has a multilayered contribution to the development of science. Firstly, it will contribute to the further development of on-purpose propane conversion technologies, which will be very important in the near future due to the projected global deficit. The new class of catalysts is still extremely unexplored, and the reaction mechanisms are not well understood. In the project, very precise kinetic measurements using the new reactor concept will be performed. The experiments will be supported by microkinetic DFT and Kinetic Monte Carlo simulations, which will be essential for obtaining an understanding the reaction pathways. Such calculations today are state-of-the-art of the available knowledge. Simulations that will be performed with computational fluid dynamics (CFD) will precisely describe the realistic system of the packed-bed reactor, by calculating the flow and concentration profiles of all the components, taking into account the realistic packing with realistic particles. Combining CFD simulations and micro-kinetics is very scarce in the available literature.
The new reactor concept, which will be designed and constructed, will by itself be a great innovation and will be the first prototype of this kind. The description of its operation will definitely be of great interest to the chemical engineering society. The expected improved performance, under conditions without mass transfer resistance, has the potential to become a standard for the determination of chemical reaction kinetics.
