Xylene Isomerization over Beta Zeolites in Liquid Phase

Abstract

An experimental study of xylene isomers interconversion (isomerization) kinetics was conducted to gain a deeper insight into the field. Two beta zeolites with SiO2/Al2O3 ratio of 35 (BEA35) and 38 (BEA38) were used as catalysts for the performed experiments. The isomerization reactions were carried out under the following conditions: 513, 493, 473, and 453 K at 2.1 MPa in liquid phase. It was verified that all reactions were in the kinetic-controlled regime. Kinetic constants were estimated with four different models; two of them were based on the xylene isomerization thermodynamic equilibrium from the literature. The linear reaction scheme, which does not consider the direct conversion between p- and o-xylene, presented a better fit to the experimental values. Higher conversion of p-xylene was observed when compared with the conversion of the other two isomers. This may be attributed to its smaller molecular size. BEA35 presented better performance due to its higher amount of Brønsted acid sites. Finally, activation energies over the two catalysts, estimated through Arrhenius equation, presented similar values.

Catalytic conversion of aromatics in fixed‐bed over several zeolites in the liquid phase

“…Among all the samples, BEA‐35 exhibited the highest amount of physisorbed isopropylamine; indeed, BEA‐type zeolites possess a large number of silanol groups. [ 39,40 ] The sample presenting the sharpest step between 550–650 K was MFI‐30, from which one can conclude that it is the sample with the highest number of Brønsted acid sites. The quantitative results of the acid sites are presented in Table 2.…”

Pressure-induced phase separation of miscible liquids: 1 : 1 n-pentane/iso-pentane

“…Several experimental and computational studies have been conducted to explore the potential of zeolites and metalorganic frameworks for the separation of isomers of hydrocarbons such as hexane and xylene. 4,5 However, this remains a challenge due to the low efficiency of separation, as the diffusivities of molecules within zeolites are typically very low. 4 A technique that can be used to separate mixtures that have very different freezing points is selective crystallisation.…”

Dearylation of Heavy Alkyl-Bridged Noncondensed Alkyl Diaromatics by Fluid Catalytic Cracking

“…High-octane, aromatic-rich reformate is a major gasoline blending component that derives from catalytically reformed low-octane naphtha . This refining stream can be further processed in an aromatic complex unit downstream of the reformate complex to recover high-value aromatics, especially basic petrochemical intermediates such as benzene, toluene, and xylenes (BTX), which are industrially important reagents for production of other chemicals, e.g., terephthalate acid for polyester production. − …”