| 摘要 |
Zeolitic molecular sieves are treated with metallic Li, Na, K, Rb, Cs, Zn, Cd, Mg, Ca, Sr, or Ba, in liquid or, preferably, vapour form whereby the metal is adsorbed within the sieve structure. Such treated sieves may be reacted with oxygen or nitrogen to convert the contained metal to oxide or nitride. The zeolitic sieves concerned are the natural zeolites, chabazite, faujasite, erionite, mordenite, gmelinite and the calcium form of analcite and the zeolitic molecular sieves, designated A, D, L, R, S, T, X and Y set forth in Specifications 777,232, 777,233, 868,846, 880,702, 882,451, 909,264, 909,265 and 909,266 respectively. Such zeolites are first heated to about 350 DEG C. to drive off substantially all of the contained water before contact with the metal. According to Examples (1) sodium zeolite X pellets were contacted at 350 DEG C. with a helium stream to remove any contained water followed at 650 DEG C., by contact with a helium stream entraining the zinc vapour; the zeolite took up 1,2 weight per cent of zinc which was converted to oxide on contact with air. (2) Zeolite X was, after dehydration, heated to 125 DEG C. and contacted with metallic sodium in a nitrogen atmosphere. (4) Sodium zeolite X pellets were mounted in a tube adjacent to a molybdenum boat containing metallic barium. After removing all water the barium was heated to 600 DEG C. and the tube evacuated to 10-5mm. Hg. whereby the zeolite took up 3,5 weight per cent of barium which was converted to oxide and nitride on exposure to air. The metal-loaded sieves may be employed as catalyst; for example a zinc or zinc oxide-loaded sieve may be employed for the synthesis of methanol, whilst an alkali metal-loaded sieve will selectively polymerize short chain olefines from an admixture with more complex branch chain olefines. The metal loaded sieves may also be employed as getters for the removal of oxygen and other gases and as a means of adding metal to other chemical systems. The oxidized barium loaded sieve is employed as a coating material for backing tube cathodes. Specification 841,812 also is referred to. |
