In this paper, the factors controlling the hydrocoprocessing of coal and wa
ste tires in tubing bomb reactors are studied. The fixed experimental condi
tions were 400 degreesC and 10 MPa of H-2 pressure. Five different coproces
sing times (60, 30, 10, 5 and 3 min) and two coal-tire ratios (80% coal-20%
tire and 20% coal-80% tire) were the studied variables. Results are compar
ed with those obtained when coal and tire were processed by isolate. At the
se conditions, it was observed that reaction time has no effect on tire con
version in obtaining the possible maximum value. However, with coal, reacti
on time is a fundamental variable because total conversion depends on it. I
n tire, reaction time has no effect on total conversion, but it affects pro
duct distribution in obtaining lower oils yields at longer reaction times d
ue to hydrocracking reactions. In hydrocoprocessing of both materials, a sy
nergism in asphaltenes formation is observed at short reaction times. This
synergism has been explained by the inter-reactions between coal and tire r
adicals. Besides, tire addition to coal hydrogenation processes improves th
e quality of the oils. (C) 2001 Elsevier Science B.V. All rights reserved.