Sc. Martin et al., EFFECT OF PRECIPITATING SOME OF THE MORE INTRACTABLE MATERIAL FROM A HYDROGEN DONOR SOLVENT COAL EXTRACT SOLUTION ON ITS HYDROPROCESSING BEHAVIOR, Energy & fuels, 12(6), 1998, pp. 1228-1234
In view of the fact that the Ni/Mo gamma-alumina catalysts currently u
sed deactivate rapidly during coal liquids hydroprocessing, the feasib
ility of removing the more intractable material from a typical coal ex
tract solution prepared with hydrogenated anthracene oil (HAO) was exa
mined by precipitation with toluene both prior to and after filtration
. The reductions in total conversion to pyridine solubles of only 3-4%
achieved were accompanied by a decline of nearly 50% in the THF-insol
uble concentrations for the modified extract solutions. As the amount
of toluene added to approximately 1 kg of the coal/HAO digest was redu
ced below 300 cm(3), the ash contents of the resultant filtered extrac
t solutions increased toward the normal concentration of ca. 0.03% obt
ained without precipitation. Batchwise and continuous hydroprocessing
tests conducted on the normal and modified coal extract solutions with
a commercial Ni/Mo gamma-alumina-supported catalyst demonstrated that
the lower concentrations of THF insolubles gave rise to significant i
mprovements in conversion for the n-hexane, toluene, and THF insoluble
s in the feeds. In accord with their higher surface areas and lower ca
rbon contents, the HDS activities of catalyst samples recovered from a
continuous run with feed modified by toluene addition were considerab
ly higher than those for the corresponding samples for the normal feed
.