Abstract: Process for producing ethers by reacting a catalytic cracking C.sub.4 olefinic cut which may contain such impurities as NaOH, an alkanolamine, an alkaline earth metal compound or an iron, copper or lead compound, with an alcohol, in the liquid phase, in the presence of an expanded bed of an etherification solid catalyst of the sulfonic resin type in acid form, in a circuit of two or more successive reaction zones wherethrough the order of passage of the reactants is periodically modified by disconnecting the first zone from the circuit, feeding the reactants to the second zone, replacing the catalyst of the first zone with fresh catalyst and thereafter connecting said first zone at the end of the circuit.

Abstract: Methyl tert.butyl ether is obtained by reacting an isobutene-containing C.sub.4 cut with methanol and distilling the reaction product at a superatmospheric pressure of 7-30 atm. abs. to recover a top fraction and a bottom fraction containing methyl tert.butyl ether. The isobutene conversion rate and the purity of the ether are increased by recycling a portion of the top fraction to the reaction zone.

Abstract: A catalyst for the steam dealkylation of aromatic hydrocarbons, comprising a carrier and 3 metals, is regenerated in the reaction zone containing the catalyst bed, after disconnection of said zone from the producing unit, by proceeding to the successive steps of: scavenging said zone with hydrogen and then with an inert gas, progressively replacing said inert gas by a gas containing molecular oxygen, burning the catalyst at a temperature lower than 650.degree. C. so as to calcine the carbon deposits of the catalyst, passing through the catalyst bed an air stream containing halogen to increase the halogen content of the catalyst, calcining by means of an air stream at a temperature of 300.degree.-600.degree. C. and purging with an inert gas before reconnecting said reaction zone to the producing unit.