B ENVIRC NMENTA L ELSEVIER Applied Catalysis B: Environmental 6 ( 1995) 79-96 Lean NO, reduction with hydrocarbons over Ga/S-ZrO, and S-GaZr/Zeolite catalysts Jennifer S. Feeley *, Michel Deeba, Robert J. Farrauto, Gagan Beri I, Alice Haynes Engelhard Corporation, 101 W ood Ave., Iselin, NJ 08830-0770, USA Received 7 November 1994; revised 3 January 1995; accepted 4 January 1995 Abstract Ga/S-ZrQ and sulfated GaZr/Zeolite catalysts were found to be very effective for the reduction of NO, in a lean environment with hydrocarbons. Ga/S-ZrO, was much more active than S-ZrO, or Ga/ZrO, as well as a wide variety of Ga supported amorphous super acids. Incorporating ZSM-5 into the catalyst formulation, i.e. S-GaZr/ZSM-5, increased NO, reduction activity particularly at low temperatures. The effects of zeolite support, sulfation, and mono vs. bimetallic supported samples were investigated. For ZSM-5, sulfation and the combination of Ga with Zr proved to be most active. Ga/S-ZrO, and S-GaZr/ZSM-5 were investigated with C,Ha, C,H6, CH,, and CO as reductants and compared to Cu/ZSM-5. Unlike Cu/ZSM-5 which was most active with C3H,, Ga/S-ZrO, and S- GaZr/ZSM-5 were more active with C,H, than with C3H,. S-GaZr/ZSM-5 was also active with CH4. All three catalysts were inactive with CO and did not catalyze the NO, decomposition reaction. Both Ga/S-ZrO, and S-GaZr/ZSM-5 were more hydrothermally stable than Cu/ZSM-5. However, their activities decreased significantly with increasing space velocity or in the presence of water in the feed making them impractical catalysts for mobile or stationary sources. Keywords: Gallium; Lean NO, reduction; Solid super acids 1. Introduction The removal of NO, from lean environments by selective catalytic reduction with hydrocarbons has received a great deal of attention recently. A successful catalyst for this application would make a significant impact on the environment. For stationary sources, such a catalyst could potentially replace the current SCR * Corresponding author. Tel. ( + l-908) 2057038; fax. ( + l-908) 3210334. ’ Gagan Beri is currently a student at Trenton State University. 0926-3373/95/$09.50 0 1995 Elsevier Science B.V. All rights reserved SSDiO926-3373(95)00004-6