Reaction Chemistry & Engineering

Journal: Reaction Chemistry & Engineering

Abbreviation

React. Chem. Eng.

Publisher

Royal Society of Chemistry

ISSN

2058-9883

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Publications 1 - 10 of 19

Towards a continuous formic acid synthesis: A two-step carbon dioxide hydrogenation in flow
Reymond, Helena; Helena Reymond, Juan J.; Urakawa, Atsushi; et al. (2018)
Reaction Chemistry & Engineering
Kinetics of nanocrystal synthesis in a microfluidic reactor: theory and experiment
Maceiczyk, Richard; Bezinge, Léonard; deMello, Andrew J. (2016)
Reaction Chemistry & Engineering
Dynamics of phase transitions in Na2TiO3 and its possible utilization as a CO2 sorbent: a critical analysis
Blanco, Maria V.; Abdala, Paula Macarena; Gennari, Fabiana; et al. (2021)
Reaction Chemistry & Engineering
Na-Based materials are emerging as promising high-temperature CO2 sorbents. In this work, we provide a detailed study on the synthesis of Na(2)TiO(3)via a solid-state route using NaOH and TiO2 as starting reactants. The CO2 sorption properties of the synthesized Na2TiO3 were evaluated by thermogravimetric analysis. A subsequent comprehensive study on the complex reaction mechanism of Na2TiO3 at high temperatures under carbonation conditions was performed via real time in situ synchrotron X-ray diffraction analysis. In situ experiments performed under different conditions revealed the occurrence of thermally-driven phase transitions derived from the structural instability of the material at high temperatures. These reactions could be differentiated from carbonation processes, allowing the proposal of a reaction mechanism of the material as a CO2 sorbent. The obtained results can explain the abnormal dynamic thermogram displayed by Na2TiO3 in the presence of CO2 within a temperature range that is of interest for practical applications and serve as a basis for evaluating the feasibility of using this material in CO2 capture schemes.
Directed evolution of Rhodotorula gracilisd-amino acid oxidase using single-cell hydrogel encapsulation and ultrahigh-throughput screening
Küng, Christoph; Vanella, Rosario; Nash, Michael (2023)
Reaction Chemistry & Engineering
Engineering catalytic and biophysical properties of enzymes is an essential step en route to advanced biomedical and industrial applications. Here, we developed a high-throughput screening and directed evolution strategy relying on single-cell hydrogel encapsulation to enhance the performance of d-Amino acid oxidase from Rhodotorula gracilis (RgDAAOx), a candidate enzyme for cancer therapy. We used a cascade reaction between RgDAAOx variants surface displayed on yeast and horseradish peroxidase (HRP) in the bulk media to trigger enzyme-mediated crosslinking of phenol-bearing fluorescent alginate macromonomers, resulting in hydrogel formation around single yeast cells. The fluorescent hydrogel capsules served as an artificial phenotype and basis for pooled library screening by fluorescence activated cell sorting (FACS). We screened a RgDAAOx variant library containing similar to 10(6) clones while lowering the d-Ala substrate concentration over three sorting rounds in order to isolate variants with low K-m. After three rounds of FACS sorting and regrowth, we isolated and fully characterized four variants displayed on the yeast surface. We identified variants with a more than 5-fold lower K-m than the parent sequence, with an apparent increase in substrate binding affinity. The mutations we identified were scattered across the RgDAAOx structure, demonstrating the difficulty in rationally predicting allosteric sites and highlighting the advantages of scalable library screening technologies for evolving catalytic enzymes.
RAFT copolymerization of oppositely charged monomers and its use to tailor the composition of nonfouling polyampholytes with an UCST behaviour
Sponchioni, Mattia; Capasso Palmiero, Umberto; Manfredini, Nicolo; et al. (2019)
Reaction Chemistry & Engineering
Synthetic polyampholytes are attracting significant interest due to the possibility that they offer of combining oppositely charged repeating units in the same copolymer chain. This peculiar structure makes them appealing for the understanding of biological processes such as protein folding and DNA condensation as well as for application as pH- and salt-responsive gels. In addition, the alternation at the molecular level of charges with opposite signs holds promise in avoiding the fouling of proteins, bacteria, and marine organisms. Indeed, polymer reaction engineering assumes an important role in ensuring such charge alternation and in turn the efficacy of the polyampholyte coating. In this work, the reversible addition–fragmentation chain transfer (RAFT) copolymerization of the electrolyte monomers 3-sulfopropyl methacrylate potassium salt (anionic, SPMAK) and [2-(methacryloyloxy)ethyl]trimethylammonium chloride (cationic, MADQUAT) was studied in detail to highlight the influence of both the monomer and chain transfer agent (CTA) concentrations on the polymerization rate and copolymer composition. By analysing the residual monomer mixture composition via in situ nuclear magnetic resonance (1H NMR), the reactivity ratios for the two monomers were calculated. Interestingly, the values obtained in the case of RAFT copolymerization (i.e. rSPMAK = 0.51 ± 0.03 and rMADQUAT = 0.31 ± 0.03) are valid in the case of a conventional free-radical copolymerization under similar conditions. The optimized polyampholytes showed interesting aqueous properties, including an upper critical solution temperature (UCST), which was studied as a function of the salt concentration and polymer molecular weight. Finally, as a proof of concept, the efficacy of the synthesized polyampholytes as nonfouling coatings was assessed in the case of A375-P cells.
Estimating speciation of aqueous ammonia solutions of ammonium bicarbonate: Application of least squares methods to infrared spectra
Milella, Federico; Mazzotti, Marco (2019)
Reaction Chemistry & Engineering
The knowledge of the speciation and of the supersaturation of aqueous solutions of CO2 and NH3 is pivotal for the design and optimization of unit operations, e.g. absorption or crystallization, in the framework of ammonia-based CO2 capture systems. For this information to be available, however, complex analytical techniques and significant experimental effort are required. This work introduces a methodology for the estimation of the concentration of species in aqueous ammonia solutions of ammonium bicarbonate by using attenuated total reflection infrared spectroscopy (ATR-FTIR) and spectral modeling based on least squares methods. In particular, the methodology can be exploited for the on-line monitoring of the liquid composition of crystallizing suspensions of ammonium bicarbonate for which the information on the speciation is combined with a rigorous thermodynamic model to compute the activity-based supersaturation. Finally, this work paves the way for the estimation of the crystallization kinetics of ammonium bicarbonate formation in aqueous ammonia solutions which is of great importance for the design of industrial CO2 capture absorption processes that exploit solid formation.
High redox performance of Y0.5Ba0.5CoO3-: δ for thermochemical oxygen production and separation
Ezbiri, Miriam; Reinhart, Anton; Huber, B.; et al. (2020)
Reaction Chemistry & Engineering
The efficient production and separation of oxygen is essential for numerous energy-intensive industrial applications in the fuel and mineral processing sectors. A thermochemical redox cycle is considered for separating oxygen from atmospheric air and other gas mixtures using solar or waste process heat. Based on electronic structure (DFT) computations Y0.5Ba0.5CoO3−δ is selected as a redox material, which surpasses the redox performance of state-of-the-art Cu2O. The thermochemical oxygen production is experimentally demonstrated by applying a temperature/pressure swing between 573 K at 0.2 bar O2 and 873 K at 1 bar O2. An energy balance shows the feasibility of using process waste heat from the solar thermochemical CO2/H2O splitting cycle and the potential to compete vis-a-vis with cryogenic distillation. Exploratory runs with a packed-bed reactor indicate the potential of both thermochemical oxygen production and separation for scale-up and industrial implementation.
Model-based development of an on-column PEGylation process
Pfister, David; Ingold, Oliver; Morbidelli, Massimo (2016)
Reaction Chemistry & Engineering
Mass transfer considerations for monitoring catalytic solid-liquid interfaces under operating conditions
Rodriguez-Garcia, Laura; Walker, Roland; Spier, Eyal; et al. (2018)
Reaction Chemistry & Engineering
Environmental and economic assessment of glycerol oxidation to dihydroxyacetone over technical iron zeolite catalysts
Lari, Giacomo M.; Mondelli, Cecilia; Papadokonstantakis, Stavros; et al. (2016)
Reaction Chemistry & Engineering

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