Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Loss of sulphur atom reduces activity of catalyst

17.03.2005


Chemical catalysts used to produce clean fuels gradually become less active. Dutch researcher Bas Vogelaar believes that the loss of sulphur atoms might be an important cause of this. He investigated hydroprocessing catalysts which remove sulphur compounds from petrol and diesel.



Crude oil contains sulphur compounds which form sulphur oxides during the combustion process. These sulphur oxides are an important source of acid rain.

Hydroprocessing catalysts are used in oil refineries to remove these sulphur compounds in order to produce clean fuels. After two years of use, the hydroprocessing catalysts have lost so much of their activity that they need to be replaced. This is an intensive and expensive operation. Vogelaar established the most important causes for the deactivation of hydroprocessing catalysts in order to increase the lifetime of these.


A hydroprocessing catalyst consists of a carrier of aluminium oxide, to which various active metals are added. A so-called active phase is created on the surface of the catalyst. The chemical reactions during which the sulphur is removed take place here. The active phase consists of a combination of molybdenum, sulphur and nickel or cobalt.

Self-cleaning

Small graphite-like particles accumulating on the hydroprocessing catalysts are one of the causes of the decrease in activity. Vogelaar discovered that this ’coke’ mainly precipitates on the carrier. He believes that the active phase has a ’self-cleaning’ effect, which can counteract the precipitation of coke. The researcher discovered that under model conditions, the activity of the catalysts mainly decreases due to the loss of sulphur from the catalyst. This process might also play a role in the deactivation of these catalysts during the production of clean fuels.

Desulphurisation

Catalysts can convert sulphur compounds in two ways. The sulphur atom is directly removed from the compound or a chemical reaction (hydrogenation) takes place after which the atom is removed. The results of Vogelaar refute the generally accepted theory that for both mechanisms a sulphur atom must first of all be removed from the active phase. For the direct removal of sulphur a so-called ’vacant position’ is indeed necessary. The hydrogenation step however takes place on sulphur atoms at the edge of the active phase and not on the ’vacant positions’. Vogelaar has used these results to produce a detailed model for the structure of the active phase. He has also developed a model which describes the desulphurisation reaction mechanism.

Dr Bas Vogelaar | alfa
Further information:
http://www.nwo.nl/nwohome.nsf/pages/NWOP_69LLET_Eng

More articles from Life Sciences:

nachricht New application for acoustics helps estimate marine life populations
16.01.2018 | University of California - San Diego

nachricht Unexpected environmental source of methane discovered
16.01.2018 | University of Washington Health Sciences/UW Medicine

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Scientists decipher key principle behind reaction of metalloenzymes

So-called pre-distorted states accelerate photochemical reactions too

What enables electrons to be transferred swiftly, for example during photosynthesis? An interdisciplinary team of researchers has worked out the details of how...

Im Focus: The first precise measurement of a single molecule's effective charge

For the first time, scientists have precisely measured the effective electrical charge of a single molecule in solution. This fundamental insight of an SNSF Professor could also pave the way for future medical diagnostics.

Electrical charge is one of the key properties that allows molecules to interact. Life itself depends on this phenomenon: many biological processes involve...

Im Focus: Paradigm shift in Paris: Encouraging an holistic view of laser machining

At the JEC World Composite Show in Paris in March 2018, the Fraunhofer Institute for Laser Technology ILT will be focusing on the latest trends and innovations in laser machining of composites. Among other things, researchers at the booth shared with the Aachen Center for Integrative Lightweight Production (AZL) will demonstrate how lasers can be used for joining, structuring, cutting and drilling composite materials.

No other industry has attracted as much public attention to composite materials as the automotive industry, which along with the aerospace industry is a driver...

Im Focus: Room-temperature multiferroic thin films and their properties

Scientists at Tokyo Institute of Technology (Tokyo Tech) and Tohoku University have developed high-quality GFO epitaxial films and systematically investigated their ferroelectric and ferromagnetic properties. They also demonstrated the room-temperature magnetocapacitance effects of these GFO thin films.

Multiferroic materials show magnetically driven ferroelectricity. They are attracting increasing attention because of their fascinating properties such as...

Im Focus: A thermometer for the oceans

Measurement of noble gases in Antarctic ice cores

The oceans are the largest global heat reservoir. As a result of man-made global warming, the temperature in the global climate system increases; around 90% of...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

10th International Symposium: “Advanced Battery Power – Kraftwerk Batterie” Münster, 10-11 April 2018

08.01.2018 | Event News

See, understand and experience the work of the future

11.12.2017 | Event News

Innovative strategies to tackle parasitic worms

08.12.2017 | Event News

 
Latest News

Gran Chaco: Biodiversity at High Risk

17.01.2018 | Ecology, The Environment and Conservation

Only an atom thick: Physicists succeed in measuring mechanical properties of 2D monolayer materials

17.01.2018 | Physics and Astronomy

Fraunhofer HHI receives AIS Technology Innovation Award 2018 for 3D Human Body Reconstruction

17.01.2018 | Awards Funding

VideoLinks
B2B-VideoLinks
More VideoLinks >>>