Grenman H.,Process Chemistry Center |
Salmi T.,Process Chemistry Center |
Murzin D.Y.,Process Chemistry Center
Reviews in Chemical Engineering | Year: 2011
Solid-liquid reactions are commonly encountered in industry as well as every day life. Vast amounts of the applied bulk and specialty chemicals are produced employing solid-liquid reactions. The knowledge of the kinetics is crucial for the design and development of these processes. Quantitative modeling of reactive solids behavior in liquids is a big challenge. The reaction mechanism can be a very complex one, often comprising several unknown elementary steps. The structure and structural changes of the solid material are also often difficult to determine. Kinetics and mass transfer effects are coupled; to determine the intrinsic kinetics, the experiments should be free from mass transfer limitations. External mass transfer resistance can be suppressed by creating strong enough turbulent effects around the solid particles, but internal mass transfer effects can be present for porous particles. Due to these facts, modeling of dissolution reactions is often simplified. Even though such simplifications are necessary, a more in-depth investigation of the related phenomena combined with quantitative studies and more thorough modeling brings new understanding and precision to process development and optimization. Several example cases of solid-liquid reactions were chosen for this work, based on their industrial relevance and varying nature. Moreover, different experimental cases were studied to illustrate a basis for the theoretical development. Two of the cases are organic reactions, while the rest are inorganic ones. The objective of the current review is to exemplify challenges related to studying solid-liquid reactions and how these challenges can be overcome. This is done through the nine example cases, which serve as good examples of the various difficulties often encountered. The published articles serve as a convenient route for finding more detailed information on the topic. Based on the literature evaluation and the experience gained in the present work, theoretical development was made based on physico-chemical fundamentals. The main advances of the current work are in the quantitative modeling of a solid phase during its reaction with a liquid. This includes the dynamic and flexible implementation of the surface morphology and particle size distribution, as well as the reaction mechanism into an overall kinetic model, in which the internal and external mass transfer phenomena are taken into account. This helps in model development and discrimination between rival models, as well as in the interpretation of curiosities in kinetic models which can be found in literature. © 2011 by Walter de Gruyter Berlin Boston.
Gemo N.,University of Padua |
Gemo N.,Process Chemistry Center |
Biasi P.,Process Chemistry Center |
Salmi T.O.,Process Chemistry Center |
Canu P.,University of Padua
Journal of Chemical Thermodynamics | Year: 2012
Hydrogen solubility in methanol, (methanol + carbon dioxide) and (methanol + carbon dioxide + oxygen) was measured and correlated at different temperatures (268 < T/K < 288) and pressures (0.37 < P/MPa < 3.5). Hydrogen content in the liquid phase was measured using a gas absorption method and Fugatron HYD-100 instrument. Experiments were performed in a fixed volume cell at constant temperature and hydrogen content was varied with subsequent loadings in the cell environment. At all conditions investigated a linear relation between hydrogen partial pressure and concentration was observed. Results were correlated and generalized as Henry's constants for H 2, as a function of temperature and CO 2/methanol overall ratio. Correlation and generalization of the measurements was provided through a thermodynamic model, based on Peng-Robinson equation of state with van der Waals mixing rules and Boston-Mathias α-function. H 2 solubility in methanol was confirmed to grow with temperature and amount of CO 2; at constant H 2 partial pressure, O 2 does not affect H 2 solubility. © 2012 Elsevier Ltd. All rights reserved.
Bober P.,Process Chemistry Center |
Bober P.,Czech Institute of Macromolecular Chemical |
Liu J.,Process Chemistry Center |
Mikkonen K.S.,University of Helsinki |
And 8 more authors.
Biomacromolecules | Year: 2014
In this work, flexible and free-standing composite films of nanofibrillated cellulose/polypyrrole (NFC/PPy) and NFC/PPy-silver nanoparticles (NFC/PPy-Ag) have been synthesized for the first time via in situ one-step chemical polymerization and applied in potential biomedical applications. Incorporation of NFC into PPy significantly improved its film formation ability resulting in composite materials with good mechanical and electrical properties. It is shown that the NFC/PPy-Ag composite films have strong inhibition effect against the growth of Gram-positive bacteria, e.g., Staphylococcus aureus. The electrical conductivity and strong antimicrobial activity makes it possible to use the silver composites in various applications aimed at biomedical treatments and diagnostics. Additionally, we report here the structural and morphological characterization of the composite materials with Fourier-transform infrared spectroscopy, atomic force microscopy, and scanning and transmission electron microscopy techniques. © 2014 American Chemical Society.
Simakova O.A.,Process Chemistry Center |
Simakova O.A.,RAS Boreskov Institute of Catalysis |
Leino A.-R.,University of Oulu |
Campo B.,Process Chemistry Center |
And 5 more authors.
Catalysis Today | Year: 2010
Gold catalyst supported on mesoporous carbon and silica were synthesized, characterized by TEM, XRD, XPS and tested in linoleic acid isomerization. Nature of the support affects the selectivity towards isomerization in relation to unwanted hydrogenation. In particular carbon support allowed much higher selectivity in double bond migration compared to silica. Effect of carbon surface oxidative pre-treatment on selectivity of catalyst was investigated. © 2009 Elsevier B.V. All rights reserved.
Kaario O.,Aalto University |
Brink A.,Åbo Akademi University |
Brink A.,Process Chemistry Center |
Lehto K.,Aalto University |
And 2 more authors.
SAE 2011 World Congress and Exhibition | Year: 2011
New measurements have been done in order to obtain information concerning the effect of EGR and a paraffinic hydrotreated fuel for the smoke and NO x emissions of a heavy-duty diesel engine. Measured smoke number and NOx emissions are explained using detailed chemical kinetic calculations and CFD simulations. The local conditions in the research engine are analyzed by creating equivalence ratio - temperature (Phi-T) maps and analyzing the CFD results within these maps. The study uses different amount of EGR and two different diesel fuels; standard EN590 diesel fuel and a paraffinic hydrotreated vegetable oil (HVO). The detailed chemical kinetic calculations take into account the different EGR rates and the properties of the fuels. The residence time in the kinetical calculations is used to explain sooting combustion behavior within diesel combustion. It was observed that NO x emission trends can be well captured with the Phi-T maps but the situation is more difficult with the engine smoke. © 2011 SAE International.