Hydrodenitrogenation of quinoline and its intermediates over sulfided NiW/γ-Al2O3 in the absence and presence of H2S

Hydrodenitrogenation (HDN) reactions of quinoline and its intermediates were carried out at 300-420 degrees C and 2-6 MPa over sulfided NiW/gamma-Al2O3 in the absence and presence of H2S. The results show that temperature and pressure have a drastic effect on nitrogen removal and production distribution in the HDN of quinoline. 1,2,3,4-tetrahydroquinoline THQ1 mainly underwent dehydrogenation to quinoline and then hydrogenated to 5,6,7,8-tetrahydroquinoline (THQ5), and decahydroquinoline (DHQ) following by ring opening elimination to give 2-propylcyclohexylamine (PCHA) and hydrocarbons. The HDN of THQ5 mainly proceeded the path of DHQ-PCHA, the reactions between THQ5, DHQ, THQ1 and quinoline are so fast that a quasi equilibrium between the four compounds is established quickly at a very low space time. The addition of H2S promotes the reaction of DHQ, but retards the pathway of OPA. The promoting effect of H2S is dominant at low concentration of H2S. However, its inhibiting effect prevails at high concentrations. The HDN via the pathway of DHQ is much easier than OPA over the sulfided NiW/gamma-Al2O3. The HDN of OPA was suppressed by the presence of Q THQ1, THQ5, and DHQ, maybe due to their stronger adsorption on the catalyst. (c) 2009 Curtin University of Technology and John Wiley & Sons, Ltd.