A

Schematic of (a) a SSITKA System and (b) Typical Steady-State Transient curves CO Oxidation. The steady state reaction results obtained at 95 C for the three-way auto-catalyst (referred to as TW) and at 100 C for the Rh La203 catalyst are shown in Table I. Although the Rh La203 catalyst had a higher metal loading, it had a much lower activity for CO oxidation. It is well known that Pt is a better catalyst for this reaction. The apparent activation energy for this reaction on the TW...

ACS Symposium Series

Joan Comstock, Series Editor 1992 ACS Books Advisory Board V. Dean Adams Tennessee Technological University Arindam Bose Pfizer Central Research Margaret A. Cavanaugh National Science Foundation Madeleine M. Joullie University of Pennsylvania Mary A. Kaiser E. I. du Pont de Nemours and Company Gretchen S. Kohl Dow-Corning Corporation Institute for Scientific Information John L. Massingill Dow Chemical Company Julius J. Menn Plant Sciences Institute, Vincent Pecoraro University of Michigan...

American Chemical Society Library 1155 16th St NW

Concentration of chlorine is reduced substantially with increasing temperature. This observation is consistent with equilibrium calculations. Formation of byproduct C2C14 is also significantly reduced. However, the rate of CO formation at low temperatures increases. Water Effect on TCE Oxidation. In another set of experiments, water was added to the feed in order to increase HC1 formation from TCE oxidation. Water can dissociate on the oxygen precovered surface of the catalyst, providing...

Catalysts

F. Prigent1'3 institut Fran ais du P trole, 92506 Rueil-Malmaison, France 2Laboratoire de Chimie-Physique, Universit de Nancy I, 54506 Vandoeuvre-les-Nan y, France Many hydrocarbon species are present in automotive exhaust gases, and three-way Pt-Rh catalysts are commonly used for their elimination. However, most published work on individual hydrocarbon conversion concerns their oxidation in simulated exhaust gases with excess oxygen. This study was therefore...

Concentration No volppm

Propane conversion rale on Pt at 260*C as a function of NO and 02 concentrations. Figures 19 and 20 quantify this H20 effect for various levels of 02 concentrations at 260 C. The effect on conversion is positive with 02 concentrations below stoichiometry and negative above. The positive water vapor effect is however completely eliminated by S02 as has already be shown for hexane. A similar Pt-Rh catalyst sample was aged at 900 C in N2 + 10 H20 during 16 hours. The resulting increase...

Effect of Ce on Performance and Physicochemical Properties of PtContaining Automotive Emission Control Catalysts

Silver2, and S. A. Bradley3 1Allied-Signal Research and Technology Center, P.O. Box 5016, Des Plaines, IL 60017-5016 2Allied-Signal Automotive Catalyst Company, P.O. Box 580970, Tulsa, OK 74158-0970 3UOP Research Center, P.O. Box 5016, Des Plaines, IL 60017-5016 Present-day automotive emission control catalysts contain noble metals such as Pt, Pd and Rh all on an alumina support with a variety of promoters. Ce is one of the most important promoters. The interaction...

Experimental Laboratory Methods

The laboratory experimental setup used for measuring hydrocarbon conversion rates is shown in Figure 1. It comprises the gas mixture generating section, the reactor and the analytical equipment. The gas flows are controlled by means of mass flowmeters. Liquid hydrocarbons and water are introduced by metering pumps and vaporized before being mixed with the main gas flow. S02 was introduced in the gas mixture for some tests by dissolving it in the injected water. The gas mixture compositions used...

K[si

Steady-State CO-NO Reaction at 200 C Activity Distribution of the Active Sites (kj average site pool activity s'1 , fraction of sites of activity kt) Figure 7. CO-NO Reaction at 200 C Reactivity Contribution of the Active Sites to the Reaction Rate (lq average site pool activity s1 , y relative contribution of the pool of sites of activities kj Figure 7. CO-NO Reaction at 200 C Reactivity Contribution of the Active Sites to the Reaction Rate (lq average site pool activity s1 , y...

Particle Size and Support Effects in NO Adsorption on Model Pt and Rh Catalysts

Gorte Department of Chemical Engineering, University of Pennsylvania, Philadelphia, PA 19104 The adsorption of NO on Rh particles supported on ZrfltylOO) and a-A CtyOOOl) and on Pt particles supported on Ce02, a- A12C> 3(0001), and the Zn- and O-polar surfaces of ZnO(OOOl) has been studied using temperature programmed desorption (TPD). Metal particles were formed by vapor deposition, and the film morphology and particle formation were studied by Auger...

Steady State Isotopic Transient Kinetic Analysis Investigation of CO02 and CONO Reactions over a Commercial Automotive

Blackmond, James G. Goodwin, Jr., and George R. Gallaher1 Chemical and Petroleum Engineering Department, University of Pittsburgh, Pittsburgh, PA 15261 Steady-state isotopic transient kinetic analysis (SSITKA) was used to study two model reactions, CO oxidation and CO-NO reactions, on a typical formulation of a three-way auto-catalyst. Under steady-state conditions, abrupt switches in the isotopic composition of CO (12C160 13C160+ 3C180) were carried out to produce...

Temperature degC

Ethylene and Propylene conversion rate on Pt-Rh at stoichiometry as a function of temperature with and without 20 vpm S02. In Catalytic C rpi qffftft Pollut yjilver, R., el al. ACS Symposium Series American Chemical Society Washington, DC, 1992. Aromatics. Benzene, toluene and orthoxylene conversion in a stoichiometric gas mixture are given as a function of temperature in Figure 6. They behave very similarly to olefins with light-off temperatures (T50) around 200-C for the three...

Thermal Decomposition of Halogenated Hydrocarbons on a Culll Surface

Bent Department of Chemistry, Columbia University, New York, NY 10027 An important step in the catalytic degradation of halogenated hydrocarbons on transition metal surfaces is the dissociation of the carbon-halogen (C-X) bond. We have investigated this process for a series of Ci - C3 alkyl bromides and iodides on a Cu(l 11) surface under ultra-high vacuum conditions. Using a variety of surface analysis techniques, we find that bromopropane and all of the alkyl...

P

Where, V bulk volume of honeycomb catalyst, cm3. F. molar feed rate, mole sec X conversion of C2HCL -rA rate of reaction of C2HC13 Equation 4 applies in the kinetic region of the conversion curve (see Figure 4) where TCE decreases from 100 to 70 over the temperature range of 250 to 350 C. Between 450 and 550 C, the reaction is mass transfer limited. Figure 8 shows plots of the logarithm of the C C Q versus residence time. A correction for a small thermal reaction component due to the monolith,...

Methane Oxidation over Noble Metal Catalysts as Related to Controlling Natural Gas Vehicle Exhaust Emissions

M. Siewert2 Physical Chemistry Department and 2Thermosciences Department, General Motors Research Laboratories, Warren, MI 48090 Natural gas has considerable potential as an alternative automotive fuel. Methane, the principal hydrocarbon species in natural-gas engine exhaust, has extremely low photochemical reactivity but is a powerful greenhouse gas. Therefore, exhaust emissions of unburned methane from natural-gas vehicles are of particular concern. This...

Selective Catalytic Reduction of Nitric Oxide with Ammonia over Supported and Unsupported Vanadia Catalysts

Kumthekar Department of Chemical Engineering, The Ohio State University, Columbus, OH 43210 Vanadia catalysts supported over titania and unsupported V205 catalysts were investigated for selective catalytic reduction of NO with NH3. All catalysts were characterized using BET surface area measurement, X-ray diffraction, in-situ and ambient laser Raman spectroscopy, X-ray photoelectron spectroscopy, and scanning electron microscopy techniques. A steady-state...

Allied Signal Automotive Catalyst Company PO Box 580970 Tulsa OK 741580970

While significant advances in Pt Rh three-way catalyst (TWC) formulations have been accomplished, the use of Pd-containing catalysts for three-way emission control are of interest for overall noble metal cost reduction, lower Rh usage, and potential durability improvements. Applications of Pd are demonstrated for replacement of Pt in conventional Pt Rh TWC systems, for use in Pd-only three-way catalysts and for lowering methanol and formaldehyde emissions at close-coupled locations on a...

Sources

Sawyer, and A. C. Frost Allied-Signal Automotive Catalyst Company, P.O. Box 580970, Tulsa, OK 74158-0970 Chapter 1 of this book outlined the legislative requirements expected for controlling the emissions from light-duty vehicles over the next decade, and how these requirements are expected to be met, particularly through the anticipated advances in the development of catalysts and their supporting systems. Similarly, this chapter reviews the provisions of the 1990...

Catalytic Oxidation of Trichloroethylene over PdO Catalyst on 7Al203

Tai-Chiang Yul, Henry Shaw1, and Robert J. Farrauto2 department of Chemical Engineering, Chemistry, and Environmental Science, New Jersey Institute of Technology, Newark, NJ 07102 2Engelhard Corporation, Menlo Park R& D, Edison, NJ 08818 Trichloroethylene is completely oxidized above 550 C to HC1, Cl2 and C02 over 4 PdO on 7-Al203 as a powder or on a cordierite monolith with 62 cells per cm2. The destruction of 200 ppm(v) TCE in air was evaluated over the temperature range 300 to 600 C in a...

Aacknowledgment Air Pollution

The authors are grateful to Octel S.A., PSA and RNUR for financial support for this project. (1) J.K. Walker and C.L. O'Hara Analysis of Automobile Exhaust Gases by mass Spectrometry. Anal. Chem. 27 (5), 825-828,1955. (2) E.S. Jacobs Rapid Gas Chromatographic Determination of Ct to C10 Hydrocarbons in Automotive Exhaust gas. Anal. Chem. 38 (1), 43-47, 1966. (3) D.J. McEven Automobile Exhaust Hydrocarbon Analysis Gas Chromatography. Anal. Chem. 38 (8), 1047-1053,1966. (4) M.W. Jackson Effect of...

Jerry C Summers Editor

Allied-Signal Automotive Catalyst Company Developed from a symposium sponsored by the Division of Colloid and Surface Chemistry of the American Chemical Society at the Fourth Chemical Congress of North America (202nd National Meeting of the American Chemical Society), New York, New York, August 25-30,1991 American Chemical Society, Washington, DC 1992 Library of Congress Cataloging-in-Publication Data Catalytic control of air pollution mobile and stationary sources Ronald G. Silver, editor,...

Catalytic Oxidation of Trace Concentrations of Trichloroethylene over 15 Platinum on 7Alumina

Farrauto2 'Department of Chemical Engineering, Chemistry, and Environmental o Science, New Jersey Institute of Technology, Newark, NJ 07102 o 2Engelhard Corporation, Menlo Park R amp D, Edison, NJ 08818 The catalytic oxidation of 40 to 250 ppm trichloroethylene in air was evaluated over 1.5 Pt 7-Al203 on a cordierite monolith with 62 cells per cm2 over the temperature range 150 to 550 C in a 2.5 cm in diameter tubular reactor at space velocities of 1,000 to...