Process of vapor phase catalytic hydrogenation of maleic anhydride to gamma-butyrolactone in high conversion and high selectivity using an activated catalyst

A process for vapor phase catalytic hydrogenation of a feed compound selected from maleic anhydride, succinic anhydride, maleic acid, succinic acid, and mixtures thereof, to gamma-butyrolactone, in a conversion of about 95%, or more, and a selectivity of about 80%, or more, which comprises:

• (a) providing an activated catalyst composition in a reactor, said catalyst being capable of production of gamma-butyrolactone for at least about 100 hours before reactivation of the catalyst, and for at least about 2000 hours without requiring fresh catalyst, comprising:
• (1) said composition consisting essentially of about 30-65% by weight of CuO, about 18-50% by weight of ZnO, about 8-22% by weight of Al.sub.2 O.sub.3, having a total pore volume of about 0.05 to 0.5 cc/g, and a surface area of about 20 to 120 m.sup.2 /g,
• (2) reducing said catalyst composition with hydrogen in a gradually increasing hydrogen concentration of from about 0.5% to about 10% initial concentration of hydrogen in an inert diluent to 100% hydrogen in the final concentration under conditions of an increasing reduction temperature of about 150.degree. to about 350.degree. C. for about 5 to 20 hours, and
• (3) activating the reduced catalyst in hydrogen at an activation temperature of at least 400.degree. C., for a period of at least about 8 hours, to provide an activated catalyst having a total pore volume of about 0.08 to 0.3 cc/g, and a surface area of about 15 to 100 m.sup.2 /g,
• (b) providing a vapor mixture of said feed compound in hydrogen at a molar ratio of hydrogen to feed compound of about 200:1 to 500:1, and
• (c) passing said vapor mixture over said activated catalyst at (i) a pressure of about 50 to 500 psig, and (ii) a feed rate space velocity of about 0.03 to 1.0 hours.sup.-1, for (iii) a contact time of less than about 10 seconds, at (iv) a reaction temperature of about 200.degree. to about 400.degree. C.,
• said process being capable of production of gamma-butyrolactone for at least about 100 hours before reactivation of the catalyst, and of at least about 2000 hours without requiring fresh catalyst.