Patent ID: 7588678

Claim:
An improved catalytic hydrocracking process in a hydrocracking reactor, comprising withdrawing from a hydrocracking reactor a recycle stream and adsorbing polyaromatic compounds from at least a portion of the recycle stream by passing said recycle stream over a capture mass consisting essentially of an adsorbent wherein the polyaromatic compounds attach directly onto solid surfaces in pores of the adsorbant and wherein the adsorbant comprises an alumina silica with a silica (SiO 2 ) content by weight of more than 5% up to 95% said adsorbant having the following properties: a mean pore diameter, measured by mercury porosimetry, in the range of 40 to 140 Å; a total pore volume, measured by mercury porosimetry, in the range of 0.1 ml/g to 0.5 ml/g; a total pore volume, measured by nitrogen porosimetry, in the range of 0.1 ml/g to 0.5 ml/g; a BET specific surface area in the range of 200 to 600 m 2 /g; a pore volume, measured by mercury porosimetry, included in pores with a diameter of more than 140 Å, of less than 0.1 ml/g; a pore volume, measured by mercury porosimetry, included in pores with a diameter of more than 160 Å, of less than 0.1 ml/g; a pore volume, measured by mercury porosimetry, included in pores with a diameter of more than 200 Å, of less than 0.1 ml/g; a pore volume, measured by mercury porosimetry, included in pores with a diameter of more than 500 Å, of less than 0.1 ml/g; an X ray diffraction diagram which contains at least the characteristic principal peaks of at least one transition alumina included in the group composed of rho, khi, kappa, eta, gamma, theta and delta aluminas; a packing density of more than 0.75 g/cm 3 .