Abstract: A process for the simultaneous replacement of a first catalyst by a second catalyst which first catalyst is circulating as a moving bed of solid particles in a hydrocarbon treating unit, which unit comprises at least one processing reactor. The first catalyst is withdrawn downstream of the reactor, or of each reactor, in the direction of catalyst circulation. The second catalyst is simultaneously injected upstream of the reactor or of each reactor. The bulk density of the material withdrawn downstream of the reactor, or of each reactor, is measured continuously. The withdrawal of the first catalyst and the injection of the second catalyst into the reactor concerned are interrupted when the bulk density so measured is equal to that of the second catalyst.

Abstract: An apparatus for the catalytic cracking in the fluid state of hydrocarbon feedstocks which comprises a riser-type column (2); at the top of the riser (2) and concentric therewith, a chamber (1) for separation of the hydrocarbon vapors and the coke-laden catalyst particles; directly above the upper opening of the riser (2) and in the interior of said chamber (1), a ballistic separator (3); at least one unit for regeneration of the spent catalyst, fed by stripped particles received from said chamber. The chamber (1) for separation of the coke-laden catalyst particles and the stripping thereof comprises, at a level intermediate between the bed (6) of particles being stripped and the opening of the riser (2), a means (11) adapted to form a baffle for locally reducing the diameter of said chamber (1) and the free passage at the periphery of the riser (2), thereby reducing recirculating streams of hydrocarbon vapors in separation chamber (1) of the FCC unit thus avoiding overcracking.

Abstract: This bitumen-polymer emulsion contains:a) at least one bitumen,b) at least one polymer having hydrocarbon chains with mobile hydrogens, said polymer being grafted and crosslinked in situ in said bitumen through a complex of at least one organic silicon compound, said complex being formed from a primary constituent and a secondary constituent, the latter being an organic silicon compound,c) water, andd) at least one emulsifier.

Abstract: A process for the fixed-bed sweetening of sour petroleum distillates with fraction temperatures of from about 125.degree. to about 350.degree. C. and having an acid number of 0.03 mg of KOH/g or higher. The reduction of the acidity and the oxidation of the mercaptans necessary for the sweetening of the distillates are carried out together in a single stage by passing the distillate, in the presence of an oxidizing agent but in the absence of a basic solution, and particularly of an alkali-metal hydroxide solution, over an oxidation catalyst whose specific surface ranges from 1 to 10 m.sup.2 /gram, and preferably from 2 to 6 m.sup.2 /gram, and whose micropore volume ranges from 0.01 to 0.10 cm.sup.3 /gram, and preferably from 0.02 to 0.05 cm.sup.3 /gram.

Abstract: The invention relates to the use of particles of sulfated lime (containing up to 80% CaSO.sub.4) as a polymer filler which can be derived from dry desulfurization of flue gas. Such sulfated lime can advantageously be incorporated into an elastomer such as ethylene propylene diene monomer rubber (EPDM) or styrene-butadiene rubber (SBR).

Abstract: A process for the substantial homogenization of the mixture of hot solid particles and of the hydrocarbon vapors to be treated within a tubular reactor (preferably an FCC unit) for the cracking of hydrocarbons in a fluidized bed of hot solid particles. Directly downstream of the zone of injection, in the reaction zone of the feedstock to be or being treated, usually where at least 75 percent of the droplets of the feedstock are vaporized, there is injected into the reactor a fluid in the gaseous state at one or more points on the interior surface of the side wall of the reactor.

Abstract: The invention relates to an apparatus which comprises a plurality of tubes made of a first material, which tubes are mounted inside a cylindrical body or shell made of a second material, which second material undergoes differential thermal expansion in relation to the first material of the tubes. The tubes are rigidly secured by their ends to two end members, at least one of which is a floating member due to the fact that it is connected to the shell by means of a flexible ring gasket. The flexible ring-type gasket has inner and outer edges which are clamped to the floating member and to the shell, respectively. The inventive apparatus is useful, for example, in the ultra filtration separation of fine catalyst particles which are in suspension in a hydrocarbon feedstock which feedstock comes from a catalytic cracking unit.