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- 2015 (26) (entfernen)
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- Prozessanalytik (8)
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- Reaction monitoring (4)
- qNMR (4)
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- Online NMR spectroscopy (3)
- Prozess-Spektroskopie (3)
- Smart Sensors (3)
- Hydroformylation (2)
Eingeladener Vortrag
- nein (15)
For absorption processes with fluctuating feed gas compositions it is vital to continuously adjust
the operation point to achieve energy efficiency. In this contribution a Raman-based advanced
process control (APC) is introduced for the absorption of carbon dioxide (CO2) using an aqueous
solution of monoethanolamine (MEA). The APC is based on a Raman spectroscopic analysis of
the composition and CO2 load of the scrubbing liquid and a non-linear model predictive control
(NMPC) to adjust the scrubbing liquid cycle. In addition, an outer real-time optimization loop is
set in place to update the set points for the absorption process depending on the current feed gas composition minimizing the energy consumption of the process. Implementation and testing of the APC have been carried out in a mini-plant at TU Berlin. During a plant operation of more than 160 hours robustness and stability of the APC were shown.
Online monitoring and process control requires fast and noninvasive analytical methods, which are able to monitor the concentration of reactants in multicomponent mixtures with parts-per-million resolution. Online NMR spectros-copy can meet these demands when flow probes are directly coupled to reactors, since this method features a high linearity between absolute signal area and sample concentration, which makes it an absolute analytical com-parison method being independent on the matrix. Due to improved magnet design and field shimming strategies portable and robust instruments have been introduced to the market by several manufacturers during the last few years. First studies with this technology showed promising results to monitor chemical reaction in the laboratory.
The Collaborative Research Center InPROMPT aims to establish a novel process concept for the hydroformylation of long-chained olefins, using a rhodium complex as catalyst in the presence of syngas. Recently, the hydroformylation in micro-emulsions, which allows for the efficient recycling of the expensive rhodium catalyst, was found to be feasible. However, the temperature and concentration sensitive multi-phase system demands a continuous observation of the reaction to achieve an operational and economically feasible plant operation. For that purpose, we tested the potential of both NMR and Raman spectroscopy for process control assistance. The lab-scale experiments were supported by sampling for off-line GC-analysis as reference analytics. The results of the NMR experiments will be part of another contribution.
Hydroformylation represents an important homogeneous catalyzed process, which is widely used within chemical industry. Usually applied with simple alkenes like Propene and Butene aldehydes obtained from alkenes >C6 are relevant intermediates in production of plasticizers, surfactants and polymers. Today the active catalyst species is often based on valuable Rhodium complexes in aqueous solution. This implies the problem of limited water solubility of the reactands, which is acceptable for short chain lengths, but states a problem in case of higher alkenes. Along with that efficient separation and recycling of the catalyst becomes more complicated. There are different approaches tackling this problem, e.g., by using of salt formation in the BASF process or downstream distillation within the Shell process
Online NMR spectroscopy as an essential tool in a multi-spectral reaction understanding approach
(2015)
Resolving overlapping peaks of multiple components. Relative primary analytical method - Fundamental relationship of qNMR.