Roles of Solvents in the Secondary Stage

The authors reported an example of such solvent effects in the catalytic two-step denitrogenation of coal liquid distillates. With large quantities of added 1-methylnaphthalene or 20% added pyrene or fluoranthene, no additional catalyst is necessary for the second step to achieve high levels of denitrogenation. 

The catalyst s resistane to coking may also be improved by the solvent while maintaining high catalytic activity. Hydrogen pressure can, thus, be reduced to 110 atm in a two-step hydrotreatment, as shown in Table II (21, 128). The two-step hydrotreatment assisted by the proper solvent not only improves the extent of hydrocracking and heteroatom removal, but it also allows the reduction of the hydrogen pressure required for efficient upgrading. 

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