Characterization of chars obtained from co-pyrolysis of coal and petroleum residues

Co-pyrolysis of coal and petroleum residue has been carried out in a bench scale unit in order to study the influence of the coal nature and the experimental conditions on the characteristics of the char obtained. Two coals of different rank, Samca (sub-bituminous) and Figaredo (bituminous), and a petroleum residue from the Maya crude have been used. Temperatures of 600, 650, and 700 degreesC, pressures of 0.1, 0.5, and 1 MPa, and mass ratios (Coal/PR) of 70/30 and 50/50 have been studied. A synergistic effect on char yields, which increases as temperature, pressure, and PR/coal ratio increase, is observed for both coals studied. Some relevant char characteristics of sulfur content, reactivity, and coking properties have been analyzed in order to determine a final use for the chars obtained. It is concluded that Samca/PR chars, especially for the 70/30 mixture, could be gasified to produce syn-gas. Coal /PR ratio higher than 50/50, temperature lower than 700 degreesC, and atmospheric pressure should be used in co-pyrolysis with Samca coal, to keep chars reactive enough to be gasified. Figaredo/PR chars, having a low sulfur content, good optical properties, and a lower reactivity could be used as a coke feedstock.