Separation and isomerization of xylenes using zeolite membranes: a short overview

Abstract

During the last 30 years, there has been a great evolution in p-xylene production technology, with many equipment improvements being instituted in the industry. Typically, these improvements bring economic as well as processing advantages to the producers. Such developments are vital, as the capital costs for process equipment to separate xylene isomers, especially into highly purified p-xylene, still remain very high. In view of this, research efforts have recently focused on the development of zeolite membranes for the separation and production of p-xylene, the precursor for the production of terephthalic acid, for which the current p-xylene world demand stands at about 86% of the production. Over a list of about 200 references, this review reports on the present state-of-the-art in p-xylene separation from lesser used isomers (o-and m-xylene) by means of MFI-type zeolite membranes, and on the most recent achievements in o/m-xylene isomerization to p-xylene using extractor-type catalytic membrane reactors.  2009

Efficient adsorption separation of xylene isomers using a facilely fabricated cyclodextrin‐based metal–organic framework

“…The isomer pX is widely used as the key raw material in the production of terephthalic acid. [10][11][12] As an emerging family of porous materials with zeolite topologies, metal-organic frameworks (MOFs) possess well-defined channels or cavities that are constructed by metal cations/clusters and functional organic linkers, making them highly suitable for diverse adsorption applications, [13][14][15][16][17][18][19] such as xylenes separation. 7 The slight differences in the boiling points of the xylene isomers lead to the difficulty and inefficiency of distillation separation processes.…”

“…8,9 Current industrial practice for separating xylenes involves slow and energy-consuming processes such as fractional crystallization, or adsorption separation on zeolites. [10][11][12] As an emerging family of porous materials with zeolite topologies, metal-organic frameworks (MOFs) possess well-defined channels or cavities that are constructed by metal cations/clusters and functional organic linkers, making them highly suitable for diverse adsorption applications, [13][14][15][16][17][18][19] such as xylenes separation. [20][21][22][23][24][25][26][27][28][29] Some MOFs show the separation mechanisms of commensurate stacking separation and molecular sieving.…”

C60‐Mediated Molecular Shape Sorting: Separation and Purification of Geometrical Isomers

“…Separation of the TMB isomers is usually carried out employing an azeotropic distillation process 9. Chromatographic separation techniques for these compounds are typically environmentally benign, despite requiring large quantities of eluents and having poor pore‐filling fractions 10. The most promising separation method for these molecules has been shown to be enclathration, however isomer recovery usually leads to byproduct formation 11.…”

Zeolite Catalysis

“…As an energy-efficient alternative to the conventional techniques, membrane reactors coupling xylene isomerization and simultaneous selective recovery represent a research topic gaining in importance in the last years due to the increasing demand of xylenes estimated at approximately 22 Mtones in 2003 [220]. Applying this concept p-xylene, the raw material for production of polyester resins could be obtained as product at the permeate side.…”