A catalyst comprises an active phase constituted by palladium, and a porous support comprising at least one refractory oxide selected from the group constituted by silica, alumina and silica-alumina, in which: the palladium content in the catalyst is in the range 0.0025% to 1% by weight with respect to the total weight of catalyst; at least 80% by weight of the palladium is distributed in a crust at the periphery of the porous support, the thickness of said crust being in the range 25 to 450 m; the specific surface area of the porous support is in the range 70 to 160 m.sup.2/g; the metallic dispersion D of the palladium is less than 20%.

The present disclosure relates to methods for selectively hydrogenating acetylene, to methods for starting up a selective hydrogenation reactor, and to hydrogenation catalysts useful in such methods. In one aspect, the disclosure provides a variety of methods for starting up reactors for use in methods for selectively hydrogenating acetylene using a catalyst composition comprises a porous support, palladium, and one or more ionic liquids.

The present disclosure relates to methods for selectively hydrogenating acetylene, to methods for starting up a selective hydrogenation reactor, and to hydrogenation catalysts useful in such methods. In one aspect, the disclosure provides a variety of methods for starting up reactors for use in methods for selectively hydrogenating acetylene using a catalyst composition comprises a porous support, palladium, and one or more ionic liquids.

The present disclosure relates to methods for selectively hydrogenating acetylene, to methods for starting up a selective hydrogenation reactor, and to hydrogenation catalysts useful in such methods. In one aspect, the disclosure provides a method for selectively hydrogenating acetylene, the method comprising contacting a catalyst composition with a process gas. The catalyst composition comprises a porous support, palladium, and one or more ionic liquids. The process gas includes ethylene, present in the process gas in an amount of at least 20 mol. %; acetylene, present in the process gas in an amount of at least 1 ppm; and 0 to 190 ppm or at least 600 ppm carbon monoxide. At least 90% of the acetylene present in the process gas is hydrogenated, and the selective hydrogenation is conducted without thermal runaway.

The present disclosure relates to methods for selectively hydrogenating acetylene, to methods for starting up a selective hydrogenation reactor, and to hydrogenation catalysts useful in such methods. In one aspect, the disclosure provides a method for selectively hydrogenating acetylene, the method comprising contacting a catalyst composition with a process gas. The catalyst composition comprises a porous support, palladium, and one or more ionic liquids. The process gas includes ethylene, present in the process gas in an amount of at least 20 mol. %; acetylene, present in the process gas in an amount of at least 1 ppm; and 0 to 190 ppm or at least 600 ppm carbon monoxide. At least 90% of the acetylene present in the process gas is hydrogenated, and the selective hydrogenation is conducted without thermal runaway.

The present disclosure relates to methods for selectively hydrogenating acetylene, to methods for starting up a selective hydrogenation reactor, and to hydrogenation catalysts useful in such methods. In one aspect, the disclosure provides a method for selectively hydrogenating acetylene, the method comprising contacting a catalyst composition with a process gas. The catalyst composition comprises a porous support, palladium, and one or more ionic liquids. The process gas includes ethylene, present in the process gas in an amount of at least 20 mol. %; and acetylene, present in the process gas in an amount of at least 1 ppm. At least 90% of the acetylene present in the process gas is hydrogenated, and the selective hydrogenation is conducted without thermal runaway. Notably, the process gas is contacted with the catalyst at a gas hourly space velocity (GHSV) based on total catalyst volume in one bed or multiple beds of at least 7,100 h.sup.1.

The present disclosure relates to methods for selectively hydrogenating acetylene, to methods for starting up a selective hydrogenation reactor, and to hydrogenation catalysts useful in such methods. In one aspect, the disclosure provides a method for selectively hydrogenating acetylene, the method comprising contacting a catalyst composition with a process gas. The catalyst composition comprises a porous support, palladium, and one or more ionic liquids. The process gas includes ethylene, present in the process gas in an amount of at least 20 mol. %; and acetylene, present in the process gas in an amount of at least 1 ppm. At least 90% of the acetylene present in the process gas is hydrogenated, and the selective hydrogenation is conducted without thermal runaway. Notably, the process gas is contacted with the catalyst at a gas hourly space velocity (GHSV) based on total catalyst volume in one bed or multiple beds of at least 7,100 h.sup.1.

A process for recovering ethylene from an FCC absorber off-gas stream comprising ethylene, ethane and heavier hydrocarbons and light gases involves removing hydrogen, nitrogen, sulfur species, carbon monoxide/dioxide, methane and other impurities from the off-gas. An absorption zone is upstream of an acetylene selective hydrotreating reactor to remove acid gases. An adsorption zone is downstream of the selective hydrotreating reactor to remove impurities that can impair ethylene recovery.

A process for recovering ethylene from an FCC absorber off-gas stream comprising ethylene, ethane and heavier hydrocarbons and light gases involves removing hydrogen, nitrogen, sulfur species, carbon monoxide/dioxide, methane and other impurities from the off-gas. An absorption zone is upstream of an acetylene selective hydrotreating reactor to remove acid gases. An adsorption zone is downstream of the selective hydrotreating reactor to remove impurities that can impair ethylene recovery.

Producing C5 olefins from steam cracker C5 feeds may include reacting a mixed hydrocarbon stream comprising cyclopentadiene, C5 olefins, and C6+ hydrocarbons in a dimerization reactor where cyclopentadiene is dimerized to dicyclopentadiene. The dimerization reactor effluent may be separated into a fraction comprising the C6+ hydrocarbons and dicyclopentadiene and a second fraction comprising C5 olefins and C5 dienes. The second fraction, a saturated hydrocarbon diluent stream, and hydrogen may be fed to a catalytic distillation reactor system for concurrently separating linear C5 olefins from saturated hydrocarbon diluent, cyclic C5 olefins, and C5 dienes contained in the second fraction and selectively hydrogenating C5 dienes. An overhead distillate including the linear C5 olefins and a bottoms product including cyclic C5 olefins are recovered from the catalytic distillation reactor system. Other aspects of the C5 olefin systems and processes, including catalyst configurations and control schemes, are also described.