Ronald M. Heck

Automobile exhaust catalysts

It has now been over 25 years since the introduction of the catalytic converter to reduce emissions from the internal combustion engine. It is considered one of the greatest environmental successes of the 20th century, however, new emission control technologies are still being developed to meet ever more stringent mobile source (gasoline and diesel) emissions. This short review will discuss the basis for improvements and highlight technology area, which will require further improvements in emissions and fuel economy. Some of the issues related to fuel cells which some believe may replace the internal combustion engines for automobile applications is also be briefly discussed.

Catalytic converters: state of the art and perspectives

Abstract This paper gives an overview of the advanced technologies currently used for abating emissions from the gasoline and diesel internal combustion engines. The challenges towards the end of the 20th century into the 21st century will also be presented.

The application of monoliths for gas phase catalytic reactions

A general introductory review of the fundamental principles of monoliths as supports for catalytic gas phase reactions is presented. Monoliths are used because of low pressure drop and high mechanical strength required for the harsh conditions encountered in environmental applications. The chemical and physical properties of monoliths and the basics for mass transfer calculations and pressure drop are presented. Existing and emerging applications are briefly discussed. Reference citations are given for those requiring more depth.

Catalytic abatement of nitrogen oxides–stationary applications

Emission regulations for unburned hydrocarbons, nitrogen oxides and particulates are becoming more stringent throughout the world. Nitrogen oxides include NO, NO2 and N2O. Transportation (mobile source) and fuel combustion (stationary source) are the main sources of nitrogen oxide emissions [1]. This review will update the commercial catalytic applications for abating nitrogen compounds (including nitrogen oxides) and will summarize the status of the following technologies applied to stationary source emissions: (1) selective catalytic reduction of NOx using ammonia (SCR); (2) non-selective catalytic reduction of NOx (NSCR); (3) nitrous oxide (N2O) decomposition; and (4) ammonia (NH3) decomposition. The major sources of NOx from stationary sources are power generation, stationary engines, industrial boilers, process heaters and gas turbines [2]. SCR is usually applied to all these sources and NSCR is applied mainly to the stationary engines. N2O decomposition is used mainly in the chemical industry associated with nylon intermediate manufacture. NH3 decomposition is a fairly new application and can be applied to SCR to decompose NH3 emissions from industrial operations.

Environmental catalysis into the 21st century

Abstract This paper describes existing catalyst technologies and trends in research as we enter the 21st century. Catalytic technologies developed during the 20th century for end-of-pipe clean up of pollutant emissions will continue for mobile and stationary sources. The catalytic problems associated with the fuel-efficient lean-burn engine, with lower emissions of greenhouse gases, offers significant challenges, especially for lean NO x reduction with on-board fuels. Monitoring pollutants using catalytic sensors will play a key role in controlling emissions from mobile and stationary sources. Decomposing ambient ozone using ‘passive’ catalytic technologies will find increasing application by the year 2000. Photocatalysis will continue to be the subject of research, but applied only in ‘niche’ markets. The proton exchange membrane fuel cell will be a major focus for research in electrocatalysis and catalytic fuel processing to make hydrogen from hydrocarbons. This technology holds great promise for stationary and vehicular power generation. The manufacture (‘Green Chemistry’) of chemicals with decreased waste and pollutants will continue to be actively pursued by many chemical manufacturers with increasing successes. The feasibility of catalytic combustion for stationary power generation with ultra-low emissions will be decided early in the 21st century. Predictions for the possibility of commercial successes will be made.

Skeletal isomerization of n-alkenes

1194833 3/1958 Fed. Rep. of Germany ...... 208/139 1420910 5/1969 Fed. Rep. of Germany ...... 208/139 2059619 12/1970 Fed. Rep. of Germany ...... 585/67

Commercial development and experience with catalytic ozone abatement in jet aircraft

Abstract A catalytic ozone abater can effectively decompose the ozone in the air that is fed to the passenger cabin of high flying commercial jet aircraft. The first commercial application of this technology was in 1983. Since that time, catalytic decomposition of ozone has become the state-of-the-art for purifying aircraft cabin air. To date, over 20,000 hours of flight time has been accumulated on many abaters. This paper describes the early development of this technology and the key performance characteristics of the catalyst. With the accumulation of flight hours, many abaters have been returned for performance tests and post analysis for causes of activity decline. This information provides details on the effect of the operating environment and the aging characteristics of the catalyst. Finally, factors that are being considered for the development of a second generation catalyst will be presented.

Deactivation regeneration and poison - resistant catalysts: commercial experience in stationary pollution abatement

Abstract The design of a commercial catalytic system requires considerable information on the operating conditions and environment in which the catalyst will function. Feed concentrations, flow rates, temperatures, pressures, and other measurements are necessary to establish a preliminary design for the required steady-state conversions. In addition, the catalyst and process design must be capable of functioning after experiencing upsets in any of the above mentioned variables. The most common causes of catalyst failure are thermal deactivation and poisoning by constituents in the gas stream. This paper describes factors leading to deactivation of catalysts in commercial stationary abatement installations. Deactivated catalysts are returned and laboratory characterization methods are used to identify failure modes. These results are used to modify the catalyst, develop methods for regeneration and to recommend plant operating conditions.

The effects of sulfur & ceria on the activity of automotive Pd/Rh catalysts

Abstract We studied Pd/Rh automotive catalysts containing varying amounts of ceria, using either high-sulfur or low-sulfur fuel. The effects of sulfur strongly depended on whether catalysts were tested under reducing conditions or at “stoichiometry,” at which oxidants and reductants are balanced. Under reducing conditions, sulfur is present as H 2 S, which strongly poisons metal surfaces. In particular, this affects activity for the oxidation of hydrocarbons. The role of ceria is complex. NO x conversion is sharply improved by ceria, especially in combination with rhodium. However, under certain conditions, ceria, due to its ability to store and release sulfur, can be shown to increase the negative impact of sulfur.

A novel approach to studying the effect of various rapid aging cycles on the performance of a high-tech, palladium-only, three-way catalyst

A new technique has been developed to assess the deterioration of hydrocarbon lightoff during FTP Phase 1. This method maps the dynamic real time data onto the hydrocarbon conversion/gas phase temperature plane to show the instantaneous hydrocarbon activity as a function of the exhaust temperature. Clearly, the map exhibits an apparent hysteresis bifurcation. The bifurcation is thought to be predominantly related to catalyst surface temperature. The hysteresis envelope of the map expands with aging severity. Therefore, the map can be used as a measure of catalyst deactivation. 13 refs., 16 figs.