Liquid Industrial Aromatics Adsorbent Separation

Zeolites have been used in the industrial adsorptive purification of aromahc petrochemicals since the early 1970s. The application of zeolites to aromatic adsorptive purification and extraction is a particularly suitable fit because of three major factors. The first is the inherent difficulty involved in separating certain aromatic components by distillation. Petrochemical production requires individual components be obtained in very high purity, often in excess of 99.5%. While distillation is the most popular method of separation in the petrochemical industry, it is not well suited for the final step of producing high purity single component streams from close boiling multi-component aromatics-rich mixtures. 

The third factor that makes zeolites particularly suitable for simple aromatic separahon is the subtle difference in adsorptive affinity between the various aromatics onto the zeolite. Zeolites, especially the eight-member ring (e.g., ZSM-5) 

Zeolites in Industrial Separation and Catalysis. Edited by Santi Kulprathipanja Copyright 2010 WILEY-VCH Verlag GmbH Co. KGaA, Weinheim ISBN 978-3-527-32505-4 

The liquid phase adsorption processes for aromatics extraction are made economically relevant by the large world demand for aromatic petrochemicals. The global per annum production rates of the highest capacity aromatic petrochemicals derived from reformate or pygas for the recent past are shown in Table 7.1. 

Benzene and para-xylene are the most sought after components from reformate and pygas, followed by ortho-xylene and meta-xylene. While there is petrochemical demand for toluene and ethylbenzene, the consumption of these carmot be discussed in the same way as the other four. Toluene is used in such a large quantity in gasoline blending that its demand as a petrochemical pales in comparison. Fthylbenzene from reformate and pygas is typically dealkylated to make benzene or isomerized to make xylenes. On-purpose production of petrochemical ethylbenzene (via ethylene alkylation of benzene) is primarily for use as an intermediate in the production of another petrochemical, styrene monomer. Ethylbenzene plants are typically built close coupled with styrene plants. 

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I 7 Liquid Industrial Aromatics Adsorbent Separation References... 

Adsorption, although originally utilized by the industry mainly in the decolonization of liquids, is also being applied to the recovery of gases, the removal of moisture from liquids tmd gases (see Fig. 7-6), the separation of aromatic hydrocarbons (by alica gel), and numerous applications in the so-called catalytic processes many of which employ adsorbents for support of the catalyst. The physical properties of some adsorbents and catalysts are indicated in Tables 10-4 to 10-6. 

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