Synergetic effects in the co-pyrolysis of samca coal and a model aliphatic compound studied by analytical pyrolysis

Pyrolysis is claimed as an alternative method to improve the quality of the products obtained from materials of a hydrocarbon nature such as coal and residues from petroleum distillation. Appearance of synergy in the production of light olefins and aromatic compounds during the co-pyrolysis of coal and petroleum residues has been previously stated. The aliphatic fraction of the petroleum residue (PR) previously studied, might play an important role in the occurrence of the synergy in coal/PR co-pyrolysis reactions. For that reason, different mixtures of Samca coal and a model aliphatic compound (C₅₀), have been co-pyrolysed at 900 °C and atmospheric pressure in a Pyroprobe 1000 CDS. Three different weight ratios coal/PR (70:30, 50:50, 40:60) were studied. Important synergetic effects were observed for the production of light olefins, specially ethylene, after the co-pyrolysis of the three mixtures, but the most intense effects appeared for the 50:50 one. Synergy in the evolution of small aromatic compounds was also observed when 70:30 mixtures were pyrolysed, but the synergy for these compounds disappeared when the ratio of pentacontane in the mixture was increased. These effects are similar to those observed when mixtures of Samca coal and PR were co-pyrolysed in the same experimental conditions, and so that, it can be concluded that the aliphatic fraction of PR is the one that leads the mechanism of the co-pyrolysis process.