Removal of unsaturated cpds. from aromatic hydrocarbon(s) - by polymerisation on silica-alumina after drying

摘要

Removal of unsaturates (olefins, dienes and acetylenes) from aromatic hydrocarbon fractions is effected by drying to an H2O content of 10-200 (pref. 10-50, esp. 15-30) ppm and then contacting with a SiO2-Al2O3 catalyst at a temp of 100-200 degrees C, a pressure of 20-60 bars and a LHSV of 0.5-5. The treatment converts unsaturates to high-boiling polymers which are readily removed by distn., giving high-purity aromatics suitable for use in the mfr. of polymers, etc. The catalyst retains a high activity for long periods (e.g. several months). The feed is pref. a BTX fraction derived from the catalytic reforming or atomizing a satd. or unsatd. gasoline feedstocks or from cracking or coal distn. operations. Drying is pref. effected by contact with a molecular sieve. The polymerisation catalyst pref. contains 60-95 (esp. 75-92) wt. %SiO2 and has a particle size of 1-5 mm.