Functions

Catalytic heaters serve many functions, especially in the oil and gas industries.  They are useful where heat production is necessary at a controlled rate. They can be used in gas meters, regulators and control valves, gas wellhead heaters, pipeline heaters, space heaters, and separators. They can also be used at the gate and compressor stations.^[6] Some other examples would include soldering irons, hand warmers, and space-heating appliances. Catalytic heaters have high efficiency allowing smaller heaters to be used, therefore lowering initial costs and fuel consumption.^[2] These heaters typically use propane (LP) or butane fuel, whereas many older types use either liquid fuel or alcohol. Handheld catalytic hand warmers have traditionally only used naphtha-type liquid fuel.

Safety

Certain safety measures should be taken when using a catalytic heater. Catalytic heaters should be installed properly to prevent fuel leakage because inhaling excessive amounts of natural gas can cause severe side effects. These heaters should all be placed in areas with good ventilation to help prevent this from happening. The user should be aware of carbon monoxide poisoning and its symptoms. As catalytic heaters are completely flameless, this takes away any inherent fire risk. These heaters have also been found to be non-incendiary when exposed to flammable gasses directly, although it can still happen on rare occasions. It’s also advised not to leave catalytic heaters unattended for any amount of time due to malfunctions that could occur and to prevent it from being knocked over. It’s also advised, for residential catalytic heaters, to turn them off while the user is asleep.^[2]

Carburetors on pre-1981 vehicles without feedback fuel-air mixture control could easily provide too much fuel to the engine, which could cause the catalytic converter to overheat and potentially ignite flammable materials under the car.[31]

Warm-up period

Vehicles fitted with catalytic converters emit most of their total pollution during the first five minutes of engine operation; for example, before the catalytic converter has warmed up sufficiently to be fully effective.[32]

In the early 2000s it became common to place the catalyst converter right next to the exhaust manifold, close to the engine, for much quicker warm-up. In 1995, Alpina introduced an electrically heated catalyst. Called “E-KAT,” it was used in Alpina’s B12 5,7 E-KAT based on the BMW 750i.[33] Heating coils inside the catalytic converter assemblies are electrified just after the engine is started, bringing the catalyst up to operating temperature very quickly to qualify the vehicle for low emission vehicle (LEV) designation.[34] BMW later introduced the same heated catalyst, developed jointly by Emitec, Alpina, and BMW,[33] in its 750i in 1999.[34]

Some vehicles contain a pre-cat, a small catalytic converter upstream of the main catalytic converter which heats up faster on vehicle start up, reducing the emissions associated with cold starts. A pre-cat is most commonly used by an auto manufacturer when trying to attain the Ultra Low Emissions Vehicle (ULEV) rating, such as on the Toyota MR2 Roadster.[35]

Environmental effect

Catalytic converters have proven to be reliable and effective in reducing noxious tailpipe emissions. However, they also have some shortcomings in use, and also adverse environmental effects in production:

An engine equipped with a three-way catalyst must run at the stoichiometric point, which means more fuel is consumed than in a lean-burn engine. This means approximately 10% more CO2 emissions from the vehicle.[citation needed] Catalytic converter production requires palladium or platinum; part of the world supply of these precious metals is produced near Norilsk, Russia, where the industry (among others) has caused Norilsk to be added to Time magazine’s list of most-polluted places.[36] The extreme heat of the converters themselves[37] can cause wildfires, especially in dry areas.[38][39][40]

The catalytic converter’s construction is as follows:

The catalyst support or substrate. For automotive catalytic converters, the core is usually a ceramic monolith that has a honeycomb structure (commonly square, not hexagonal).

(Prior to the mid 1980s, the catalyst material was deposited on a packed bed of alumina pellets in early GM applications.) Metallic foil monoliths made of Kanthal (FeCrAl)[16] are used in applications where particularly high heat resistance is required.[16]

The substrate is structured to produce a large surface area

The cordierite ceramic substrate used in most catalytic converters was invented by Rodney Bagley, Irwin Lachman, and Ronald Lewis at Corning Glass, for which they were inducted into the National Inventors Hall of Fame in 2002.[4] The washcoat. A washcoat is a carrier for the catalytic materials and is used to disperse the materials over a large surface area. Aluminum oxide, titanium dioxide, silicon dioxide, or a mixture of silica and alumina can be used. The catalytic materials are suspended in the washcoat prior to applying to the core.

Washcoat materials are selected to form a rough, irregular surface, which increases the surface area compared to the smooth surface of the bare substrate.[17] Ceria or ceria-zirconia. These oxides are mainly added as oxygen storage promoters.[18] The catalyst itself is most often a mix of precious metals, mostly from the platinum group.

Platinum is the most active catalyst and is widely used, but is not suitable for all applications because of unwanted additional reactions and high cost. Palladium and rhodium are two other precious metals used.

reduction catalyst

Rhodium is used as a reduction catalyst, palladium is used as an oxidation catalyst, and platinum is used both for reduction and oxidation. Cerium, iron, manganese, and nickel are also used, although each has limitations.

Nickel is not legal for use in the European Union because of its reaction with carbon monoxide into toxic nickel tetracarbonyl.[citation needed] Copper can be used everywhere except Japan.[clarification needed] Upon failure, a catalytic converter can be recycled into scrap.

The precious metals inside the converter, including platinum, palladium, and rhodium, are extracted.