Chemical Engineering & Technology

Cover image for Vol. 37 Issue 4

Impact Factor: 1.366

ISI Journal Citation Reports © Ranking: 2012: 55/133 (Engineering Chemical)

Online ISSN: 1521-4125

Associated Title(s): Chemie Ingenieur Technik, ChemBioEng Reviews, Energy Technology

Editors' Choice

Every month, the Editors select two papers referring to current discussions in the scientific, public and economic communities and in view of the potential for further developments. The papers are freely accessible for one month.

Stirred-tanks Reactors

April 04, 2014

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Stirred-tanks reactors with gas self-inducing impellers are widely used in laboratories and industry to perform gas-liquid or gas-liquid-solid reactions such as alkylations, chlorinations, ozonolysis, hydrogenations, transesterifications, etc. Existing studies focus mainly on industrial-scale reactors in spite of the widespread use of stirred reactors at lab-scale. Scale-up and scale-down or the development of novel reactor designs cannot be easily done with the results or methodologies presented in the literature. As an alternative, the adoption of computational fluid dynamics (CFD) as a simulation tool allows the study of aerated stirred-tank reactors. However, the computational description of turbulent multiphase flows in stirred tanks can be too challenging in terms of time and resources, and is often presumed to be only applicable to fields of fundamental research. V. Santos-Moreau et al. described a simplified methodology for prediction of the gas renewal rate from self-inducing impellers in stirred-tank reactors. In its validity domain, the presented CFD methodology is a validated tool for the prediction of the gas renewal rate from self-inducing impellers, reducing complexity by avoiding the need of including two-phase flow modeling.


Cláudio P. Fonte, Bruno S. Pinho, Vania Santos-Moreau and José Carlos B. Lopes
Prediction of the Induced Gas Flow Rate from a Self-Inducing Impeller with CFD
Chem. Eng. Technol. 2014, 37 (4), 571–579.
DOI: 10.1002/ceat.201300412


 

Acrolein Oxidation to Acrylic Acid

April 04, 2014

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Acrylic acid (AA) is one of the most important chemical intermediates. It is produced industrially from partial oxidation of propene in a two-step heterogeneously catalyzed process. The acrolein formed in the first step is then converted into AA on modified Mo/V-mixed oxide catalysts. To date, the exact relationship between the structure of the catalyst and the reaction mechanism is, in the main, still unknown. One reason for this is the complexity of these catalysts in which different solid phases occur side by side. Since the specific activation of oxygen on these mixed oxide catalysts adopts a central role, a kinetic study of the oxygen incorporation and removal is of significant help. H. Vogel et al. described the simulation of steady-state isotopic transient kinetic analysis (SSITKA) experiments carried out with a tubular-reactor dispersion model, which takes into account the concentration gradients along the catalyst bed. A mixed oxide with the formal stoichiometry Mo8V2W0.5Ox was used as a model catalyst. With the help of 18O2-SSITKA, understanding of the reaction paths of oxygen was expanded successfully and an extended reaction model was deduced.


Alfons Drochner, Philip Kampe, Nadine Menning, Nina Blickhan, Tim Jekewitz and Herbert Vogel
Acrolein Oxidation to Acrylic Acid on Mo/V/W-Mixed Oxide Catalysts
Chem. Eng. Technol. 2014, 37 (3), 398–408.

 

Carbon Dioxide Absorption

March 04, 2014

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In the last years, the use of tertiary alkanolamines in carbon dioxide absorption processes or in purification of gas effluents that have impurities from acidic gases, e.g., CO2 and H2S, experienced an impressive development. Previous studies analyzed the carbon dioxide absorption process in tertiary alkanolamine solutions using different gas-liquid contactors, considering kinetic aspects of the chemical reaction, absorption rate and mass transfer coefficient. However, no accurate values for the mass transfer coefficient could be obtained. La Rubia et al. analyzed the absorption process of carbon dioxide in aqueous solutions of triethanolamine with a bubble-column reactor as contactor and applying NMR spectroscopy to evaluate the reaction mechanism and reaction stoichiometry. Hydrodynamic and absorption studies were performed regarding the evolution of all parameters over time. These studies allowed investigating the influence of operation variables with a lower uncertainty for liquid-side mass transfer coefficients.


Ana B. López, M. Dolores La Rubia, José M. Navaza, Rafael Pacheco, Diego Gómez-Díaz
Carbon Dioxide Absorption in Triethanolamine Aqueous Solutions: Hydrodynamics and Mass Transfer
Chem. Eng. Technol. 2014, 37 (3), 419–426.
DOI: 10.1002/ceat.201300603



 

Carbide-Derived Catalyst Supports

March 04, 2014

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Structured catalyst or reactors are an upcoming field in reaction engineering as they provide advantages compared to conventional fixed-bed systems, like combining low pressure drop with enhanced heat transport or resistance against particles in a fluid flow. Among structured reaction systems, ceramic monoliths are found as well as ceramic foams and metal structures. Etzold et al. presented three different approaches towards structured catalysts based carbide-derived carbon (CDCs). These materials are of interest as they can be tuned in terms of pore size distribution, specific surface area, and the degree of order in the carbon itself. The resulting structured catalyst supports were characterized in detail and applied in the model reaction of ethene hydrogenation. All methods resulted in highly active catalysts. The choice of method, which differed in complexity and costs, was influenced by the process and prerequisite.


Tilman Knorr, Aaron Schwarz, Bastian J. M. Etzold
Comparing Different Synthesis Procedures for Carbide-Derived Carbon-Based Structured Catalyst Supports
Chem. Eng. Technol. 2014, 37 (3), 453–461.
DOI: 10.1002/ceat.201300582



 

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