Abstract: Hexenes are produced when propylene is catalytically converted under moderate conditions over chosen small pore zeolite catalysts having small 10-membered ring openings. These chosen catalysts are ZSM-22, ZSM-23, ZSM-35, and ZSM-48. They are unexpectedly effective to dimerize a substantially ethylene-free propylene-rich stream to form mainly hexene isomers, a major portion of which isomers are tert-isohexenes, without making a substantial amount of trimer or other byproducts. The feed is preferably at least 60% by weight, the remainder being alkanes, mainly propane, and the olefins being limited to less than 5 mol % ethylene and less than 5 mol %, preferably less than 2 mol %, of C.sub.4.sup.=+ (mainly butenes). Because propane in the feed is essentially unaffected, plural reactors in series may be used to avoid recycling unreacted propylene with propane to the dimerization reactor.

Abstract: A process for production of ether by hydration and etherification of olefinic feedstock containing at least one lower alkene by contacting the olefinic feedstock and water in a plurality of catalytic reaction zones containing porous solid metal oxide acidic olefin hydration and etherification catalyst under olefin hydration and etherification conditions. Improved operation is achieved by recovering a first effluent stream from at least one fixed bed hydration zone, splitting the first effluent stream into a product recovery stream and a plurality of recycle streams, and passing at least a portion of cooled recycle streams comprising olefin, alcohol and ether in effluent stream component proportions for quenching at least one fixed bed reaction zone to control temperature of hot effluent from a preceding reaction zone.