Way to increase the efficiency of a reactions: steady and unsteady state catalysis

In the lecture on the example of the process of benzene hydrogenation taking into account the presence of thiophene in the feed gas was discussed approaches to the developing of the unsteady state kinetic model and process optimization. On the base of the kinetic model the theoretical analysis of the reactor performance under unsteady state conditions and unsteady state was carried out.It is shown that for periodic reactor operation an average conversion was up to several times higher than the steady state value

Plant Nutrient Resource Use Strategies Shape Active Rhizosphere Microbiota Through Root Exudation

Plant strategies for soil nutrient uptake have the potential to strongly influence plant–microbiota interactions, due to the competition between plants and microorganisms for soil nutrient acquisition and/or conservation. In the present study, we investigate whether these plant strategies could influence rhizosphere microbial activities via root exudation, and contribute to the microbiota diversification of active bacterial communities colonizing the root-adhering soil (RAS) and inhabiting the root tissues. We applied a DNA-based stable isotope probing (DNA-SIP) approach to six grass species distributed along a gradient of plant nutrient resource strategies, from conservative species, characterized by low nitrogen (N) uptake, a long lifespans and low root exudation level, to exploitative species, characterized by high rates of photosynthesis, rapid rates of N uptake and high root exudation level. We analyzed their (i) associated microbiota composition involved in root exudate assimilation and soil organic matter (SOM) degradation by 16S-rRNA-based metabarcoding. (ii) We determine the impact of root exudation level on microbial activities (denitrification and respiration) by gas chromatography. Measurement of microbial activities revealed an increase in denitrification and respiration activities for microbial communities colonizing the RAS of exploitative species. This increase of microbial activities results probably from a higher exudation rate and more diverse metabolites by exploitative plant species. Furthermore, our results demonstrate that plant nutrient resource strategies have a role in shaping active microbiota. We present evidence demonstrating that plant nutrient use strategies shape active microbiota involved in root exudate assimilation and SOM degradation via root exudation

Application of Ultrasound Measurements as PAT Tools for Industrial Crystallization Process Development of Pharmaceutical Compounds

Within this work, 12 different pharmaceutical compounds were analyzed by the single-frequency ultrasound measurement technique for its applicability to determine concentrations, as an important process parameter during crystallization processes, or to determine the metastable zone widths, as an important precondition for the development of crystallization processes. The results were compared to the applicability of inorganic and nonpharmaceutical compounds that have been discussed in the literature. It was found that according to the change of ultrasound velocity and adiabatic compressibility, a grouping of compounds can be derived. From this grouping it can be concluded that some organic compounds and especially inorganic compounds show an excellent applicability for concentration determination, while the application for pharmaceutical compounds is most often limited. Furthermore, a cost- and time-efficient possibility is shown for the integration of this technique in a pilot-plant-scale setup. A direct transferability of calibration models developed at the laboratory scale was found as long as the influence of undissolved air/gas was low in the pilot-plant setup

Integration of Process Analytical Technology Tools in Pilot-Plant Setups for the Real-Time Monitoring of Crystallizations and Phase Transitions

In this study it was demonstrated that the usage of an access unit connected to a pump-around loop cycle is a good solution for the integration of various online analytical measurement techniques in pilot-plant or industrial-scale reactors without time and cost intensive modifications of the existing setup. As a model system the crystallization as well as the polymorphic transition of α- and β-l-glutamic acid (LGA) was investigated in real-time by Raman-, NIR-, and UV–vis spectroscopy. All three techniques have been shown to be powerful tools for the process optimization of crystallizations. While all three techniques can be used for the detection of the dissolution point and the crystallization end point, Raman-spectroscopy has the advantage of being able to provide quantitative information on the actual polymorph solid fraction in the solid product. In this work special interest was put into the possibility to transfer quantitative spectroscopic models, which were established on laboratory scale, to pilot-plant scale. Furthermore, it was successfully shown that it is possible to use spectroscopic models, which originated from the calibration of solid mixtures of the polymorphs by off-line Raman spectroscopy, for the evaluation of Raman spectra recorded in suspensions during the crystallization processes. In case of the quantification of α- and β polymorph content in LGA samples peak integration (PI) as well as partial-least-squares (PLS) models were established for solid binary mixtures using the software PEAXACT (S-PACT GmbH). It was possible to transfer the PI model (valid for solid mixtures) also for evaluation of the spectra of suspensions. Consequently, the model can be applied not only in a lab scale but also for pilot plant or industrial scales

Pilot Plant PAT Approach for the Diastereoselective Diimide Reduction of Artemisinic Acid

In this study, an attractive route for the diastereoselective synthesis of dihydroartemisinic acid (DHAA) starting from artemisinic acid (AA) is presented. Diimide was used as a reducing agent, which was generated by two different methods: (1) by the reaction of hydrazine monohydrate and hydrogen peroxide and (2) by the reaction of hydrazine monohydrate and oxygen. Both methods were found to be suitable for the diimide reduction of AA showing full conversion and a high diastereoselectivity. Due to advantages in the crystallization step of DHAA, the second option for generation of diimide was chosen for the pilot plant scale-up. The reaction and the crystallization process development as well as the batch production in the pilot plant were monitored and controlled using dispersive Raman spectroscopy as PAT tool. Three DHAA batches in kilogram scale were successfully produced by the reaction of artemisininic acid, hydrazine monohydrate, and a gas mixture of nitrogen and oxygen (containing 5% v/v oxygen) in 2-propanol at 40 °C. Excellent yields of >90% (including the crystallization, isolation, and drying step) as well as high diastereoselectivities (≥97:3) of the products were achieved by the elaborated pilot plant manufacturing processes

Application of Ultrasound Measurements as PAT Tools for Industrial Crystallization Process Development of Pharmaceutical Compounds

Within this work, 12 different pharmaceutical compounds were analyzed by the single-frequency ultrasound measurement technique for its applicability to determine concentrations, as an important process parameter during crystallization processes, or to determine the metastable zone widths, as an important precondition for the development of crystallization processes. The results were compared to the applicability of inorganic and nonpharmaceutical compounds that have been discussed in the literature. It was found that according to the change of ultrasound velocity and adiabatic compressibility, a grouping of compounds can be derived. From this grouping it can be concluded that some organic compounds and especially inorganic compounds show an excellent applicability for concentration determination, while the application for pharmaceutical compounds is most often limited. Furthermore, a cost- and time-efficient possibility is shown for the integration of this technique in a pilot-plant-scale setup. A direct transferability of calibration models developed at the laboratory scale was found as long as the influence of undissolved air/gas was low in the pilot-plant setup