Why do catalysts need replacing

Having already fitted his filters to warehouse forklift trucks, by the s Houdry had begun to research catalytic converter technology for use on cars and he secured a patent for his design in Today, the overwhelming majority of internal combustion engined cars on the road have a catalytic converter and there are various different kinds fitted to different models. Have you been a victim of catalytic converter theft? Let us know in the comments below Skip to Content Skip to Footer.

In this guide we explain everything you need to know about catalytic converters - from how they work to the materials and precious metals used in them - and how to protect your car from catalytic converter theft… How do catalytic converters work?

Park your car in a locked garage or a well lit area in public view with the rear of the car close to a wall or fence. Ask a local garage to weld the bolts on your catalytic converter or use other commercial anti-theft devices that will make it harder to remove.

History of the catalytic converter Catalytic converters have been around since the 19th century when metal cylinders containing filters coated in platinum, Iridium and palladium were fitted to early French motor cars in an attempt to clean up the smoke coming out of their exhausts.

This table summarises some common catalysts used in industry and the reactions they catalyse:. Activation energy is the minimum energy needed for a reaction to occur when two particles collide. It can be represented on an energy level diagram. The diagram shows that when a catalyst is used, the activation energy is reduced. This makes more of the collisions successful at a given temperature. For example, zeolite Y is a natural mineral used in catalytic cracking to turn crude oil into useful chemicals, and the synthetic zeolite ZSM-5 is used for hydrocarbon isomerization and alkylation reactions.

Hutchings of Cardiff University, a leading expert in heterogeneous catalysis. But can chemists come up with better uses of mineral resources to make catalysts that are more sustainable? For a growing number of researchers, the answer is yes, and the key is taking advantage of materials that are already out of the ground. Red mud, the noxious by-product of the Bayer process for extracting aluminum from bauxite ore, makes a good case study.

The majority of material processed in mining operations ultimately goes to waste. For every ton of alumina extracted from bauxite, more than a ton of red mud is produced; aluminum mining leaves behind some million metric tons per year of the salty, highly alkaline, heavy-metal-laden material, according to the International Aluminum Institute.

Some 4 billion metric tons of the material is lying about globally, much of it held in retention ponds. Mining companies have long tried to find ways to recycle the environmentally problematic red mud. It is a classic problem in search of a solution. One approach is neutralizing red mud with seawater or treating it with CO 2 or sulfur compounds. The modified materials have been tried as fill for mining and construction, as pigment and filler for bricks and cement, and as a sorbent for water treatment.

Others have looked at extracting more aluminum from red mud, or obtaining other useful metals such as sodium, copper, and nickel. But so far there have been few safe and economical large-scale applications. On a new front, some chemists are trying to go catalytic, focusing on iron oxide, the chief component of red mud. But given the purity and properties of red mud, researchers have found it typically is not an active enough catalyst to compete against existing commercial catalysts.

With red mud, finding the right combination is a work in progress. One early sign of success comes from Foster A. They have been testing red mud as a bulk catalyst to replace zeolites in a fluidized-bed reactor to pyrolyze biomass to make crude oil Energy Fuels , DOI: The team processes the biocrude oil using a traditional catalytic hydrotreating process to make a gasoline-type fuel and has tested it on a lawn mower or lawn trimmer.

The Utah State researchers have applied for a patent for their process. The team is also expanding the scope of using red mud beyond biomass pyrolysis, Agblevor says.

The researchers have applied the catalyst to coal gasification, he notes, as well as to a process for catalytic pyrolysis of waste tires for fuel production. For example, industrial processing, the use of consumer goods and medicines, and even the wearing away of jewelry leads to measurable amounts of catalyst metals such as gold, silver, and platinum accumulating at wastewater treatment plants.

One of the more prolific sources of these metals, though, is catalytic converters. Automobiles in the U. They do a good job on vehicle emissions by zapping pollutants such as unburned hydrocarbons, carbon monoxide, and nitrogen oxides and turning them into more benign products such as CO 2 , water, and nitrogen.

But as cars putt down the road, catalytic converters slowly disperse platinum, palladium, rhodium, and cerium into the environment. Researchers who have assessed the abundance of these dissipative metals think the concentrations are high enough in the environment, or will be over time, to make it worthwhile to recover them because of their high market values.

To assess the situation, environmental engineer Sebastien Rauch of Chalmers University of Technology and his colleagues measured platinum, palladium, and rhodium concentrations and fluxes in the environment using high-volume air particulate sampling.

Concentration ratios of the metals and trace osmium isotope ratios allowed the team to peg catalytic converters as the source of the metals, rather than natural or industrial sources. And harvesting the metals from the air could certainly have some limitations. It is of course possible to sample for longer periods, but platinum amounts would remain relatively small. Testing out the idea, geoscientist Hazel M. Prichard of Cardiff University, who passed away on Jan.

Prichard had the idea that recovering the metals could be as simple as scooping up samples from the street or roadsides, storm drains, and wastewater treatment plants. Prichard even investigated the collection bins in the bellies of street-sweeping machines.

Several years ago, Prichard and her colleagues collected samples in Sheffield, England, finding gold primarily from jewelry, and platinum, palladium, and rhodium from catalytic converters. The platinum, palladium, and rhodium combined made up as much as 1. They also found more than 3 ppm of gold, platinum, palladium, and rhodium concentrated in incinerated sewage sludge ash. By comparison, Prichard estimated that the minimum concentration needed to economically extract platinum-group metals from ore deposits is 2—4 ppm.

As Rauch points out, mechanical sieving could potentially help concentrate the metals for use as catalysts. As another option, Prichard and her team enlisted biochemist Lynne E. Macaskie of the University of Birmingham to help develop a fermentation process for metal-absorbing microbes to extract metals from the dust.

Macaskie and her colleagues have tested palladium-containing bacterial biomass as a bioinorganic catalyst for cleaning up industrial waste and for hydrogenation reactions, finding that the material has potential for industrial applications, she says. Although recovering metals could prove lucrative, Prichard was motivated by the fact that global supplies of precious metals are limited.

Lipshutz of the University of California, Santa Barbara. Lipshutz and his group have taken a minimalist approach to organic synthesis , using the smallest possible amount of catalyst and organic solvent to see how green and efficient they can make everyday reactions. In one case, they showed that parts-per-million traces of palladium impurity in iron chloride is enough to catalyze cross-coupling reactions.

Finding creative ways to recycle such gifts from nature are clearly important challenges we face, but they are problems we can solve. Contact the reporter. Submit a Letter to the Editor for publication. Engage with us on Twitter. The power is now in your nitrile gloved hands Sign up for a free account to increase your articles. Or go unlimited with ACS membership.

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