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Sergio Carra

Bio: Sergio Carra is an academic researcher from Instituto Politécnico Nacional. The author has contributed to research in topics: Catalysis & Adsorption. The author has an hindex of 8, co-authored 17 publications receiving 370 citations.

Papers
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Journal ArticleDOI
01 May 1986
TL;DR: In this article, a mathematical model containing three population balance equations has been defined for precipitation of titanium dioxide by thermal hydrolysis from concentrated sulfuric acid solutions by considering all the factors which have influence on the rates of the process and on the characteristics of the precipitate.
Abstract: Precipitation of titanium dioxide by thermal hydrolysis from concentrated sulfuric acid solutions has been studied by considering all the factors which have influence on the rates of the process and on the characteristics of the precipitate. For this purpose a mathematical model containing three population balance equations has been defined. A population balance equation is related to the free particles that are present at any time in the system, another to the agglomerates, and the last to the total particles, that is free particles plus particles bounded into the agglomerates. In this model kinetic laws for nucleation and growth, respectively, have been introduced by considering the experimental observations that precipitation is a strongly activated process and that sulfuric acid concentration negatively affects precipitation rate. The following assumptions have then been introduced: coalescence is possible only for very small free particles; and elementary particles in aggregates can grow independently without losing their identity. The above-mentioned population balance equations have been solved by employing the method of moments and give the amount of titanium precipitated during the time, the average size of the elementary particles and of the aggregates during the time, and the evolution of the corresponding distribution function. The reliability of the mathematical model has been tested on kinetic runs performed under different conditions of temperature, titanium concentration, and sulfuric acid concentration.

108 citations

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TL;DR: In this article, the authors compared the performance of four different catalysts in the alkylation of phenol with methanol, and provided information about the reaction path models, mechanisms and kinetics.

90 citations

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TL;DR: In this article, six samples of H-ZSM5 zeolites, differing in the size of crystallites and acidity, have been tested as catalysts in the alkylation of phenol with methanol.

55 citations

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TL;DR: The separation process of a mixture of chlorotoluene isomers through adsorption on molecular sieves has been investigated in this article, where two exchanged zeolites, of t

32 citations

Journal ArticleDOI
TL;DR: In this article, the role of desorbent in bulk separation processes in gaseous phase based on displacement chromatography is analyzed in detail, and the optimal desorbents are characterized by adsorptivity intermediate between those of the components to be separated.

23 citations


Cited by
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Journal ArticleDOI
TL;DR: In this paper, the preparation of a colloidal colloidal by un procede sol gel is described, and a procedure for determination des proprietes electriques et electrochimiques is described.

2,040 citations

Journal ArticleDOI
TL;DR: In this paper, the application of countercurrent and simulated counter-current process schemes to adsorption separations is reviewed with emphasis on industrial-scale operations and mathematical modelling, and the results of the application are presented.

476 citations

Journal ArticleDOI
TL;DR: In this paper, the formation of uniform silica particles is investigated and rates of silicon alkoxide reactions are reported and linked to particle growth rates, which are consistent with a particle growth mechanism involving reactions occurring in solution that proceed independently of the presence of particles.

419 citations

Journal ArticleDOI
TL;DR: In this article, an aggregative growth model for the formation of uniform particles was developed and tested with rate and particle size distribution data gathered on spheres precipitated from silicon alkoxides.

398 citations