Oxide Gas Purification 'Cleanses' Harmful Pollutants in Car Emissions

Improvements to exhaust gas purification in petrol or diesel cars were indeed essential in the effort to reduce emissions because switching to electric cars is a laborious process.

A study team has created an oxide based on cerium and zirconium that improves the ceramics' ability to cleanse pollutants inside catalytic converters, a part of traditional cars that transforms dangerous gases into less-toxic pollutants.

Ceramics breathe oxygen at low temperatures

(Photo : Matt Boitor/Unsplash)

Catalytic converters, which are found in nearly all gasoline and diesel vehicles, remove dangerous hydrocarbons, carbon monoxide, and nitrous oxide from the exhaust and transform them into safer gases like nitrogen, carbon dioxide, and water vapor.

The harmful gases pass through a honeycomb structure that has catalysts for exhaust gas purification coated on it, as per ScienceDaily.

The purification process depends heavily on ceramics having an oxygen storage capacity (OSC). The precious metals in catalytic converters are kept from coarsening, which would reduce their ability to purify gases, and they aid in the removal of harmful gases.

By manipulating its crystal structure, a research team at Tohoku University's Graduate School of Engineering has created a Cerium-Zirconium-based (Ce-Zr) oxide with good OSC at 400 ºC.

Even without the use of precious metal catalysts, the OSC at 400 ºC was 13.5 times greater than that of ordinary materials.

The transition metal doping in the oxides produced two distinct impacts. By facilitating the development of oxygen vacancies and fostering cation ordering, it sped up the diffusion of oxygen.

The iron doping decreased the cation-ordering temperature, allowing the Ce-Zr-based oxides to have more surface area. This improved their toughness and capacity to remove harmful gases. Takamura and his team intend to test the substance in the future by palladium loading it on honeycomb supports.

Disadvantages of Ceramic engines

Despite the advantages, ceramics aren't necessarily the only material to use in aeronautical design. Ceramics present difficulties in machining and pricing, as manufacturers have also discovered, as per Metal working.

Don Graham, manager of education and technical services at Seco Tools, argues in an article for Manufacturing Engineering that the same characteristics that increase strength and temperature resistance can make machining more challenging.

Graham notes that the challenge arises at the final machining or grinding phase, in which the surface integrity of the ceramics is jeopardized if cut wrongly. Furthermore, a high material removal rate increases the likelihood of being compromised even more.

According to Alexander Gorin and M. Due to the brittle nature, high hardness, resistance to creep, and high strength of advanced ceramics, standard machining techniques like turning, milling, and drilling are difficult to execute well due to cracks, brittle fractures, and edge chipping. Advanced Ceramics: Some Challenges and Solutions in Machining by Conventional Methods by Mohan Reddy.

A piece of ceramic that has been improperly machined will have much less structural strength. The overall structure will lose a substantial degree of rigidity if sandwiched composite material is sliced with ragged, uneven, or distorted edges.

According to the Gorin/Reddy report, given the importance placed on a strong, effective cut when machining ceramics, it is understandable why many shops have been known to devote up to 80% of their total costs to preserving the integrity of their ceramics-based structures.

Naturally, this can be problematic when trying to stick to a budget or allocate money for other job-related expenses.