High selectivity, high activity direct ethylene oxidn. silver catalyst - with alpha-aluminium oxide carrier surface area and tungsten co-promoter amt. restricted to set ranges

摘要

Novel alkali metal-promoted Ag catalysts claimed for use in direct oxidn. of ethylene to ethylene oxide are characterised by (i) having an alpha-Al oxide porous carrier of BET surface area 0.3-3 m2/g; and (ii) contg. tungsten as co-promoter in an amt., based on total catalyst wt., of 60-330 wt. ppm per m2 surface area per g of the carrier material. Ag content is 10-30 wt.% and the alkali metal is Li, Rb and/or Cs with prefd. amts. based on total catalyst wt., being 200-2000 wt.ppm for Cs and/or Rb and 100-1000 wt.ppm for Li. At least 99 wt.% of the carrier is of high-purity alpha-Al oxide.