Ifp's New Flexible Hydrocracking Process Combines Maximum Conversion with Production of High Viscosity, High Vi Lube Stocks

Hydrocracking

“…This mass transfer of silica within the zeolite creates a secondary, larger pore structure: the so-called mesopores as illustrated in Fig. 6.11 (52). The mesoporosity has been shown to reduce masstransport limitations during hydrocracking and thereby suppress secondary cracking.…”

“…6.10). Another important property of stabilised zeolite-Y materials is their mesoporosity (52). As previously discussed, aluminium is removed from the framework during steaming and the resulting lattice defects are (partially) healed by silica which migrates from other parts of the structure.…”

Cracking and Hydrocracking

“…Hydrocrackers can be very large units, with feed intakes up to 3 million tons per year. Different hydrocracking processes exist [101][102][103][104][105], with different process configurations. Most hydrocrackers have fixed-bed reactors in which the liquid oil feedstock and gaseous hydrogen are passed in downflow over the catalyst beds (so-called trickle flow), and typically operate at pressures in the range of bar and at temperatures in the range of 300-450 • C. Two basic schemes, which are widely applied, can be identified: two-stage hydrocracking and single-stage hydrocracking (see Figure 18.11).…”

“…Indeed, a little hydrogen is already sufficient to dislodge Ga 3+ from the faujasite framework. Mesoporosity brought about by ultrastabilization of zeolite-Y materials [104] (Figure 18.21) has been shown to reduce mass-transport limitations during hydrocracking and thereby suppress secondary cracking. For heavy feeds, the activity is also improved by enhanced accessibility, as has been recently confirmed in a comparison between HC of tetralin and of atmospheric residue [171].…”

“…A recent PQ patent describes stabilized Y materials with much enhanced mesoporosity [172], and it turns out that indeed such materials can lead to increased middle-distillate selectivity. It has even been claimed that the selectivity pattern of mesoporous zeolite-Y approaches that of an ASA [104], although this has not been well substantiated [148]. As yet, the influence of zeolite-Y mesopore structure has not been considered in model studies.…”