Improved tools for bubble column reactor design and scale-up☆

Studies in tower reactors with viscous liquids on flow regime, effective shear rate, liquid mixing, gas holdup and gas/ liquid mass transfer (k
La) are reviewed. Additional new data are reported for solutions of glycerol, CMC, PAA, and xanthan in bubble columns with diameters of 0.06, 0.14 and 0.30 m diameter. The wide variation of the flow behaviour index (1 to 0.18) allows to evaluate the effective shear rate due to the gas flow. New dimensionless correlations are developed based on the own and literature data, applied to predict k
La in fermentation broths, and compared to other reactor types.

Viscous media in tower bioreactors: Hydrodynamic characteristics and mass transfer properties

The effects of liquid-phase viscosity, pseudoplasticity, and viscoelasticity on gas-liquid mass transfer in a bubble column have been investigated using aqueous solutions of sucrose, xanthan, polyacrylamide, and mixtures of xanthan and polyacrylamide. The elastic properties, considered in the form of the Weissenberg number, decreased the volumetric mass transfer coefficient by a factor of up to 5. The effect was strong even at low Weissenberg numbers encountered in many liquids, the elasticity of which is usually neglected.



On a etudie les effets de la viscosite, de la pseudoplasticite et de la viscoelasticite de la phase liquide sur le transfert de matiere gaz-liquide dans une colonne a bulles en utilisant des solutions aqueuses de sucrose, de xanthane, de polyacrylamide et de melanges de xanthan et de polyacrylamide. Les proprietes elastiques, exprimees en terme du nombre de Weissenberg, diminuent le coefficient de transfert de matiere volumetrique par un facteur allant jusqu'a 5. L'effet est important měme avec les petits nombres de Weissenberg rencontres dans beaucoup de liquides et dont l'elasticite est generalement negligee.

Gas-liquid mass transfer in the bubble column with viscoelastic liquid

Provided herein are catalysts useful in reductive amination, which include nickel, copper, zirconium and/or chromium, oxygen, and tin. The presence of the tin increases the selectivity of the catalyst in reductive aminations over the catalysts of the prior art.

Advances in amination catalysis

The invention relates to a method of preparing metallic nanoparticles and to the materials thus obtained. More specifically, the invention relates to a method of preparing metallic nanoparticles consisting in: selecting a precursor from the salts, hydroxides and oxides of metallic elements that can be reduced at temperatures below the clay silicate network destruction temperature; and depositing said precursor on a support selected from pseudolaminar phyllosilicate clays. According to the invention the method comprises: (i) a deposition step in which the precursor is deposited on the support: (ii) when the precursor is selected from among salts and hydroxides, a thermal decomposition step in a controlled atmosphere, in which the precursor is subjected to a decomposition process and is transformed into an oxide of the metallic element: and (iii) a reduction step in which the oxide of the metallic element is subjected to a reduction process in a controlled atmosphere. The aforementioned method is performed at temperatures below the clay silicate network destruction temperature.

Method of preparing metallic nanoparticles and materials thus obtained

The subject invention relates to a catalyst comprises 1-75% of iron oxide, 1-10% of titanium metal oxide and the balance being attapulgate useful for the preparation of alkylated aromatic amines.

Process for the preparation of a new catalyst useful for producing alkylated aromatic amines

The present invention relates to a process for the preparation of alkylated aromatic amines which comprises reacting an aromatic amine selected from aniline, toludine, xylidine, N-methyl aniline, N-ethyl aniline, m-ethyl aniline, p-ethyl aniline, o-ethyl aniline with a primary or secondary alcohol selected from ethanol, methanol, isopropyl alcohol in the presence of attalpulgite impregnated with combination of iron oxide and oxides selected from transition metals of the periodic table as a catalyst prepared by the method described and claimed in our co-pending U.S. patent application Ser. No. 09/047,718 at atmospheric pressure and at a temperature in the range of 300-400° C. and recovering the desired amine by conventional methods.

Process for producing alkylated aromatic amines with high selectivity using new catalyst

Hochviskose Medien in Blasensäulen: Hydrodynamik und Stoffaustausch†

A catalyst suitable for use in the alkylation of aromatic amines which comprises attapulgite together with iron oxide and one or more transition metal oxides.

Catalyst for the alkylation of aromatic amines

of EP1002789A process for the preparation of alkylated aromatic amines which comprises reacting an aromatic amine with an alcohol in the presence of a catalyst which comprises attapulgite together with iron oxide and one or more transition metal oxides.

Patwari Akash N R

Papers

Process for the preparation of a new catalyst useful for producing alkylated aromatic amines

Process for producing alkylated aromatic amines with high selectivity using new catalyst

Hochviskose Medien in Blasensäulen: Hydrodynamik und Stoffaustausch†

Catalyst for the alkylation of aromatic amines

Preparation of alkylated aromatic amines