VERFAHREN ZUR HERSTELLUNG VON PHTHALSAEUREANHYDRID DURCH GASPHASENOXIDATION EINES ORTHOXYLOL-NAPHTHALIN-GEMISCHES.

摘要

In prepn. of phthalic anhydride from a mixt. of o-xylene and naphthalene, by gas phase oxidn., (a) a soln. of 1-80 pts. wt. of naphthalene and 99-20 pts. of o-xylene is prepd. at 0-80 deg.C, and is stored at this temp., (b) shortly before reaction, the mixt. is heated to 110-180 deg. C and (c) the heated soln. is led, in an air stream at 150-200 deg. C, over a metal oxide catalyst. Pref. (a) the soln. contains 30-65 (40-60) pts. wt. of naphthalene and 70-35 pts. of o-xylene. The naphthalene is esp. distilled or a crystallisate with solidification point 78-80 deg. C. The temp. is 30-70 (40-60) deg. C. Solns. with higher concns. of naphthalene, up to 80 pts. wt., are diluted, before or after heating, with further o-xylene, to between 1 and less than 80 pts. of naphthalene, and are sprayed into an air stream at 150-200 deg. C. Opt., freshly distilled naphthalene, at 80-120 deg. C is dissolved in o-xylene, and the soln. is heated to 110-180 deg, C and sprayed into the hot air stream and led over the metal oxide catalyst.