NI- AND Pd/C-CATALYZED HYDRODENITRO-GENATIONS OF ISOQUINOLINE

摘要

Nitrogen removal from coals has being an important subject in clean coal technology. Different from sulfur, almost all the nitrogen is believed to be present as organic species, especially in aromatic rings [1]. In fact, nitrogen atoms in organonitrogens detected from extracts of coals themselves [2] and mixtures [3] from hydrothermal treatment of coal residues are present both in and out of aromatic rings. Since nitrogen removal from aromatic rings in coals is much more difficult and challenging, related investigations have attracted great attention. Catalytic hydrogenation is generally necessary for nitrogen removal from aromatic rings. To understand mechanisms for catalytic hydrodenitrogenation (HDN) from coals and to optimize related processes, reactions of various aromatic nitrogen compounds (ANCs) were extensively investigated. Miki and Sugimoto [4] compared the reactivities of quinoline and isoquinoline (IQ) toward HDN and hydrogenation over sulfide Ni-Mo/Al_2O_3 in the temperature range 300-375 ℃ for 15-20 min. They found that compared to quinoline IQ HDN is much easier but hydrogenation is difficult. Mochida et al. [5] examined the influence of hydrogen pressure in Ni-Mo-P/ AlCl_3-catalyzed HDN of pyridine, aniline and quinoline in decalin with and without addition of carbon disulfide (CS_2). They concluded that increasing hydrogen pressure improved aniline HDN more significantly than pyridine HDN; hydrogen sulfide resulting from the reaction of hydrogen with CS_2 promoted quinoline HDN more effectively than hydrogen alone and that the reactivity of the ANCs and their products toward HDN is related to their adsorption stength on catalyst surface.