Alkylaromatics in Detergents Manufacture: Modeling and Optimizing Linear Alkylbenzene Sulfonation

Linear alkylbenzene sulfonic acid (ASA) is the main ingredient of many commercial formulations for industrial and domestic synthetic detergents. The current industrial ASA production method includes sulfonation of linear alkylbenzene (LAB) with sulfur trioxide in tubular falling‐film reactors. The present study investigates the influence of light alkylaromatics on the efficiency of ASA production. After dealkylation and polymerization, these aromatic compounds form viscous components in the sulfonation reactor. This increases the organic liquid viscosity and disrupts the uniformity of sulfonation. We present the results of IR analysis of the LAB and ASA samples, which indicate that the viscous components are sulfones that are part of the unsulfonated matter. With due consideration of the sulfonation process reaction network, we developed a mathematical model for a sulfonation reactor considering the alkylaromatics content in the feed flow and its effect on the reaction rates. The results allowed the improvement of sulfonation process in terms of increasing the number of days between the reactor washings. The sulfur flow rate increased from 371.7 to 380.9 kg h^?1 at the end of this period for the aromatics content in LAB of 4 wt.% and from 372.1 to 380.1 kg h^?1 for aromatics content in LAB of 6 wt.%. The proposed modifications of the process modes can increase the SO₃ conversion up to 98%.     

Thermodynamic stability of coke-generating compounds formed on the surface of platinum dehydrogenation catalysts in their oxidation with water

Results of thermodynamic analysis and mathematical simulation of the deactivation of a platinum dehydrogenation catalyst by coke-generating compounds are presented. An approach to increasing the catalyst on-stream time has been proposed, suggesting implementation of a procedure for calculating the optimal flow rate of water fed to the reactor to maintain the conditions of thermodynamic equilibrium of the coke formation reaction and oxidation of intermediate condensation products with water.     

Computer Prediction of Catalytic Reforming of Naphtha Cuts

Experience in the use of a computer system (CS) developed with consideration of the physicochemical properties of catalytic reforming of naphtha cuts for testing and selection of the type of Pt catalyst, optimization of the conditions of its treatment and industrial use, prediction of the duration of the operating cycle between regenerations, and the increase in the efficiency of operation of industrial units in consideration of the process technology and hydrocarbon composition of the refined feedstock is described.     

A comparative study on Cu,Cr and As removal from CCA-treated wood waste by dialytic and electrodialytic processes

In this study, electrodialytic and dialytic techniques were used for Cu, Cr and As removal from 20-years out-of-service CCA-treated Pinus pinaster Ait. pole. The effect of applying direct current, as "cleaning agent", of up to 120 mA was investigated. Focus was given to a parallel comparison with the performance of a pure dialytic experiment (without an external power supply) in order to reveal transport of charged particles induced solely by internal electrochemical potential differences in the system. Oxalic acid proved to be a more suitable pre-treatment solution than deionised water for wood chips incubation. Evaluation of the IARs of Cu, Cr and As showed that the rates of their appearance in the electrolytes were not linearly related to the current (except for Cr in the catholyte), mainly because of membrane retention. The maximum removal efficiencies obtained in a batch electrodialytic cell operated for 14 days were as follows: Cu, 84%; Cr, 87%; and As, 95%.     

Comparative analysis of catalyst operation in the process of higher paraffins dehydrogenation at different technological modes using mathematical model

Abstract

This paper presents the results of comparative analysis of three run cycles of platinum catalyst for higher paraffins C₉–C₁₄ dehydrogenation process, performed using mathematical model. The results of model calculations were compared with the experimental data obtained at the industrial unit. It was established that deactivation of the platinum dehydrogenation catalyst is influenced by the technological modes of its operation, such as temperature, pressure, hydrogen/feedstock molar ratio and water supply. In the process of higher paraffins dehydrogenation, the phenomenon of platinum catalyst self-regeneration is observed. This occurs due to the action of feedstock components, in particular water and hydrogen involved in oxidation and hydrogenation of intermediate condensation products (coke structures). Model calculations showed that with a decrease in the hydrogen/feedstock molar ratio and simultaneous increase in water supply, depending on the temperature and composition of feedstock, it is possible to slow down deactivation process and increase the catalyst service life. This fact was experimentally confirmed at industrial unit.     

Effect of thermodynamic stability of higher aromatic hydrocarbons on the activity of the HF catalyst for benzene alkylation with C9-C14 olefins

Results of thermodynamic analysis of reactions occurring during the alkylation of benzene with C₉-C₁₄ olefins, including the reversible reactions of formation of high-molecular-mass aromatic hydrocarbons, are presented. The thermodynamic relationships revealed have formed the basis for deriving a mathematical model of the alkylation process with allowance for alteration in the activity of the HF catalyst. It has been shown that the buildup of higher aromatic hydrocarbons in the alkylation reactor has a detrimental effect on the properties of HF. Operating modes and controlling parameters of the main stages of the production f linear alkylbenzenes to ensure the maximal efficiency of the process and maintain the activity of the HF catalyst at the optimal level have been determined.