| abstract |
1504319 Isoprene TAKEDA CHEMICAL INDUSTRIES Ltd 3 April 1975 [3 April 1974] 13653/75 Heading C5E [Also in Division B1] Isoprene is made by condensing formaldehyde and isobutylene in the presence of a solid catalyst comprising silver ions, aluminium oxide and silicon oxide, the atomic ratio Al: Ag::1:10 to 30:1 and the weight ratio aluminium oxide:silicon oxide::1:5000 to 2:1. The catalyst may also contain an oxide and/or ions of one or more elements chosen from the transition elements, the alkaline earth metals, zinc, boron, thallium, tin, lead and phosphorus and may be activated by heating at 100-1400‹ C. in the presence of air, an inert gas, oxygen, hydrogen and/or steam. After use the catalyst may be regenerated by heating at 300-800‹ C. in air, oxygen or steam. The condensation reaction may be at a temperature higher than 180‹ C. with a space velocity of 1-1000 moles/hr./litre of catalyst. An inert gaseous diluent may be present and the isobutylene is preferably used in excess. |