Additive Effects of Phenols on Hydrodenitrogenation of Acidic, Neutral and Basic Fractions in Coal Liquids

The liquid products derived from Miike coal were separated into weakly acidic (WA1), strongly acidic (SA1), neutral-hexane insoluble (N-HI1), basic-benzene soluble (B-BS1), and basic-benzene insoluble and dichloromethane solu-ble (B-BI1) fractions. The additive effects of phenols on their denitrogenation (DN) were investigated in detail by the hydrogenolysis reactions with a sulfided Co-Mo/Al2O3 catalyst. Additive effect of phenol could not be observed in DN of WA1, due to the increased acidity of the catalyst caused by phenols in WA1. However, phenol addition was very effective in DN of SA1 containing only a small amount of phenols. When 7.0% of phenol was added to N-HI1, the hydrogenolysis was promoted by the catalyst of increased acidity. The adsorption of nitrogen-containing aromatic rings of B-BS1 on the catalyst surface was inhibited by the steric hindrance of long-chain alkyl groups bonded to aromatic rings. Therefore, phenol addition did not affect the DN of B-BS1. On the other hand, the DN of B-BI1, which does not have long-chain alkyl groups bonded to aromatic rings, was slightly promoted by phenol addition. Cresol isomers were as effective as phenol for the DN.