Pyrolysis and hydropyrolysis of amberlite IRC50 and some of its metal-exchanged forms

Abstract

As a model for part of the structure of low-rank coals, a cation exchange resin (Amberlite IRC50) and several of its metal-exchanged forms were studied by differential thermal analysis in nitrogen and in high-pressure hydrogen, and also by simultaneous thermogravimetry and mass spectrometry. The pyrolysis temperatures decreased in the sequence: Na ⪢ Ba ⪢ Ca ⪢ Zn ⪢ Co ⪢ Bi ⪢ Sn ⪢ Pb ⪢ Fe ⪢ Ni. The presence of high-pressure hydrogen complicated the results for the reducible metals. Because the peak temperature of the lead form was similar to those of iron, nickel and tin, which are known to catalyse hydrogenation reactions, it is concluded that lead is worthy of investigation as a potential catalyst for coal hydrogenation. The combination of nickel and cobalt, and of lead and iron appear to act synergistically in hydrogen, so they too may be effective catalyst combinations. Since sodium, potassium and calcium occur commonly in low-rank coals, they may inhibit the onset of decomposition reactions during processing at typical coal-processing temperatures of about 400°C.