Phthalic anhydride process
AssigneeExxonMobil Chemical Patents Inc.
InventorsNicolaas A. de Munck, Raul Zweevel, Annemieke de Winter, Liza De Geeter, Theo Wandel
Life of this patent
Estimating the term…
Abstract
Disclosed is an improved process for the production of phthalic anhydride wherein the spent catalyst is removed from the oxidation reactor tubes more effectively by vacuuming from the top and using a vacuum hose having a tip with an increased impact strength and with a maximum hardness. As a result, the new catalyst loading can be made more uniform and the process may be operated with improved stability at higher organics loadings in the reactor feed. Process stability may be further improved by varying the outlet temperature of the phthalic anhydride precondenser over time.
Claims15
A process for the production of phthalic anhydride comprising contacting a gaseous mixture of ortho-xylene or naphthalene and an oxygen-containing gas with an oxidation 5 catalyst comprised in vertical tubes of a tubular reactor, the process comprising after using the catalyst taking the tubular reactor out of production service, removing the used catalyst and loading more active catalyst into the reactor tubes, whereby used catalyst is removed from the reactor tubes by vacuum hosing through a vacuum hose or tube that is introduced into the reactor tube from the top and characterised in that the tip of the 10 vacuum hose or tube comprises a material that has (i) a notched Izod impact strength, according to ASTM D256, of at least 55 J/m, or a U-notched Charpy impact strength at 23° C., according to ISO 179, of more than 5 kJ/m2, and (ii) a Shore D hardness, according to ISO 868, of at most 90.
Dependencies are inferred from the claim text.