Energy & Fuels 1990,4, 599-604
599
Influence of Catalyst Properties and Operating Conditions on Hydrodenitrogenation of Quinoline H. A. Rangwala, I. G. Dalla Lana,* F. D. Otto, H. Yeniova, and K. Al-Nuaimi Department of Chemical Engineering, University of Alberta, Edmonton, Alberta, Canada T6G 2G6 Received November 9, 1989. Revised Manuscript Received July 16, 1990
Results are reported for the catalytic hydroprocessing of quinoline blended into a heavy atmospheric gas oil (HAGO) by using seven different commercial catalysts. The studies were carried out in a CSTR a t temperatures of 380-420 "C, pressures of 7-17.3 MPa, and space velocities of 11-23 cm3/(h-g of catalyst). The nitrogen concentrations were varied from 0.3 to 0.96 wt % and were thus comparable to those generally found in coal-derived liquids. Limited hydroprocessing studies were also done for a coal-derived liquid (Saarbergwerke Process Oil) using both a Ni-Mo and a Ni-W catalyst. The Ni-Mo catalysts were the superior catalysts, with an optimum Ni/Mo ratio of about 0.24. The kinetic studies show that a first-order rate expression is applicable for feed nitrogen content below 0.3 wt % . At higher concentrations of nitrogen in the feed, an inhibition effect due to the presence of nitrogen was observed. The catalyst effectiveness factor based on the first-order reaction rate model for HDN reactions was found to be about 0.8-0.9.
Introduction Catalytic hydroprocessing of coal-derived liquids is done with the objective of removal of the detrimental constituents, nitrogen, sulfur, and oxygen. It also leads to some restructuring of the hydrocarbon constituents by hydrocracking. Nitrogen is generally considered to be much more difficult to remove than sulfur and oxygen. Thus, it is appropriate to focus these experimental catalyst evaluation studies on the denitrogenation aspect of coal liquid upgrading. Nitrogen is generally present in the form of five- or six-membered heterocyclic compounds, and quinoline-type compounds make up about 8-32 wt 70 of the total.' Flinn et ala2reported studies on hydrodenitrogenation (HDN) of pure quinoline and other nitrogen-containing model compounds and found that quinoline is more difficult to denitrogenate than indole. In a comparative study, Shih et al.3 examined HDN of quinoline (feed N = 0.11 wt W ) using Ni-Mo, Co-Mo, and Ni-W catalysts on an alumina support. They found that Ni-Mo catalysts were superior in HDN activity compared to Co-Mo or Ni-W catalysts. Recently, Curtis et al.4 have reported a study on HDN of quinoline using precipitated transitionmetal sulfides from group VIB and VI11 metals and found their activities to be comparable to Ni-Mo or Co-Mo catalysts. The kinetics of the reaction of hydrogen with quinoline and other nitrogen compounds have been studied by many investigators. The rate constants for intermediate steps for quinoline HDN have been determined by Satterfield5 and Shih et a1.6 An activation energy based on a first-order rate constant for overall HDN of quinoline using Cc-Mo-A1203 catalyst was reported by Aboul-Gheit' (1) Akgerman, A.; Anthony, R. G. Reprints from the AIChE Diamond Jubilee Meeting, Washington, D.C., October 1983; AIChE: New York, 1983; Fiche 56, Paper 27d. (2) Flinn, R. A.; Larson, 0. A.; Beuther, H. Hydrocarbon Process. Pet. Refin. 1959,42 (9), 129. (3) Shih, S.; Reiff, E.; Zawadski, R.; Katzer, J. R. P r e p . - A m . Chem. SOC.,Diu. Pet. Chem. 1978,23 (l),99. (4) Curtis, C. W.; Cahela, D. R. Energy Fuels 1989,3, 168. (5) Satterfield, C. N.; Gultekin, S. Ind. Eng. Chem., Process Des. Deu. 1981,20,62. (6) Shih, S.; Katzer, J. R.; Kwart, H.; Stiles, a. B. Prepr.-Am. Chem. SOC., Diu. Pet. Chem. 1977,22 (3), 919.
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Table I. Properties of HAGO and Saarbergwerke Process
Oil
boiling range, O C density, g/cm3 sulfur, w t 5% nitrogen, wt 70 naphtha (bp
