THE AMERICAN SOCIETY OF MECHANICAL ENGINEERS 345 E. 47th St., New York, N.Y. 10017 97-AA-77 The Society shall not be responsible for statements or opinions advancedin papers or crtecussion at meetings of the Society or of its Divisions or Sections, or printed in its publications. Discussion is printed only if the paper is published in an ASME Journal. Authorization to photocopy material for intemal.or personal use under circumstance not falling within the fair useProvisions °MS Copyright Act is granted by ASME to libraries and other users registered with the Copyright Clearance Center (CCC) Transactional Reporting Service provided that the base fee of S0.30 per page is paid directly to the CCC, 27 Congress Street Salem MA 01970. Requests for special permission or bulk reproduction should be adiresSed to the ASME Technical Publishing Department CopyrigM 0 1997 by ASME All Rights Reserved Printed in U.S.A Catalytic Control of SI Engine Emissions over Ion-Exchanged X-Zeolites Randip K. Das, B. B. Ghoshl, Souvik Bhattacharyya Department of Mechanical Engineering EA 111111111 II 11111 and Maya DuttaGupta Department of Chemistry Indian Institute of Technology, Kharagpur 721302, India Abstract Three catalysts based on X-zeolite have been developed by exchanging its Na+ ion with Copper, Iron and Nickel metal ions and tested in a SI engine exhaust for a wide range of exhaust and operating conditions. Of the three catalysts, the Cu-X catalyst exhibits the best NO. and CO conversion performance while Ni-X shows slightly better performance compared to the Fe-X catalyst at any catalyst temperature. Unlike noble metals, the doped X-zeolite catalysts, studied here, exhibit significant NO 1 reduction for a wide A range and exhibit a slow rate of decrease with increase in A ratio. Back pressure developed across the catalyst bed is found to be well-affordable and power loss due to back pressure is only 0.216% at space velocity of 52500 /h. During 30 hours of testing of each catalyst, no significant deactivation of any catalyst is observed. Keywords : NO R , CO, Zeolite, Catalyst, Conversion Efficiency 1 Introduction Three-way catalysts (TWC) are extensively used for simultaneous control of the three princi- pal automotive pollutants, namely, carbon monoxide (CO), hydrocarbons (HC) and oxides of nitrogen (N04. But, these catalysts are not effective at reducing NO„ level in exhaust gases containing excess oxygen. Thus, closed-loop A-control system is required to control the amount of oxygen in the exhaust gas from engines. While conventional gasoline vehicles, with closed loop A control system, operate within the working range of the TWC for the whole operating range, lean-burn gasoline engines have to enrich their air-fuel ratio at higher loads. Lean Otto engines with homogeneous mixture have a potential for fuel efficiency improvement of 5 to 15% compared to current SI engines with TWC. The efficiency gain for DI - gasoline engines is even greater [1]. Thus, the removal of NO x in presence of excess oxygen is an important issue demanding immediate action. In particular, decomposition or reduction of nitrogen monoxide (NO) is a dominant target to be achieved because NO is inert and also the major component (more than 95%) of NO 1 in exhaust gases. It is well known that NO is thermodynamically un- stable relative to N2 and 0 2 at temperatures below 1200 K [2] and its catalytic decomposition is the simplest and the most desirable method for its removal. 'Author for correspondences Presented at the ASME ASIA '97 Congress & Exhibition Singapore - September 30-October 2,1997 Downloaded from https://asmedigitalcollection.asme.org/GT/proceedings-pdf/TA1997/78675/V001T13A053/4460245/v001t13a053-97-aa-077.pdf by guest on 30 June 2020