Hydrochloric acid boosts catalyst activity

August 25, 2020

A research team from the Technical University of Munich (TUM) led by chemist Johannes Lercher has developed a synthesis process which drastically increases the activity of catalysts for the desulfurization of crude oil. The new process could perhaps also be used for catalysts in fuel cells.

Crude oil contains a great deal of sulfur. To turn the crude oil into fuel, the sulfur compounds must be removed using hydrogen. Experts call this process hydrotreating. The process is carried out using catalysts.

Under the leadership of Prof. Johannes Lercher and Dr Hui Shi, a team of researchers at the Professorship of Chemical Technology at the Technical University of Munich have now developed a process to increase the activity of these catalysts many times over by treating the catalytically active metal sulfides with concentrated hydrochloric acid beforehand.

Important for the environment

Hydrotreating is one of the most important catalytic processes - both with regard to the quantity of catalyst used and the quantity of processed raw material. With highly pressurized hydrogen, impurities such as sulfur or nitrogen compounds are removed from the crude oil as completely as possible.

"These kinds of impurities would later combust to form sulfur dioxide and nitrogen oxides, which would result in negative effects on the environment especially the air quality," says Manuel Wagenhofer, first author of the study. In addition, sulfur and nitrogen compounds would also damage precious metals in catalytic converters in modern vehicles, and drastically reduce their effectiveness.

An amazing effect of hydrochloric acid

The TUM chemists examined such mixed metal sulfide catalysts for their effectiveness in hydrotreating by first synthesizing nickel molybdenum sulfides over several process stages, and then treating them with acid.

"It was amazing how much adding concentrated hydrochloric acid increased the catalytic performance," says Wagenhofer. "Hydrochloric acid improves the accessibility of active centers in the catalysts by removing less active components, mainly nickel sulfides. Purer, and therefore more active, mixed metal sulfides are formed."

Great advantages for fundamental research

The TUM chemists' results are also very important for fundamental research. The purified mixed metal sulfides are also easier to examine, scientifically.

"For example, we were able to identify and quantify active centers on the catalysts that were treated in this way," explains Lercher. "This was only possible because the surface was no longer covered in nickel sulfide."

In principle, the acid treatment could apparently be used as an investigation instrument for a series of similar catalysts, to optimize these, for example, for use with oils from renewable raw materials which are to be transformed into climate-friendly fuels in the future via a refining process.

"If we understand mixed metal sulfide catalysts better, we can perhaps improve them considerably for use in other important fields of the future, such as water electrolysis or hydrogen fuel cells," says Johannes Lercher.
-end-
Publication:

Enhancing hydrogenation activity of Ni-Mo sulfide hydrodesulfurization catalysts.
Manuel F. Wagenhofer, Hui Shi, Oliver Y. Gutierrez, Andreas Jentys, Johannes A. Lercher.
Science Advances 2020, Vol. 6, no. 19, eaax5331, DOI: 10.1126/sciadv.aax5331
https://advances.sciencemag.org/content/6/19/eaax5331

More information:

Parts of this work were funded by Chevron Energy Technology Company and the Federal Ministry of Education and Research (BMBF) in the framework of the MatDynamics joint project. X-ray absorption spectrums were recorded at the PETRA III Synchrotron source of the German Electron Synchrotron (DESY) in Hamburg.

Contact:

Prof. Dr. Johannes A. Lercher
Professorship of Chemical Technology and Catalysis Research Center
Technical University of Munich
Lichtenbergstr. 4, 85748 Garching, Germany
Tel.: +49 89 289 13540 - E-Mail: johannes.lercher@ch.tum.de

Technical University of Munich (TUM)

Related Nitrogen Articles from Brightsurf:

Chemistry: How nitrogen is transferred by a catalyst
Catalysts with a metal-nitrogen bond can transfer nitrogen to organic molecules.

Illinois research links soil nitrogen levels to corn yield and nitrogen losses
What exactly is the relationship between soil nitrogen, corn yield, and nitrogen loss?

Reducing nitrogen with boron and beer
The industrial conversion of nitrogen to ammonium provides fertiliser for agriculture.

New nitrogen products are in the air
A nifty move with nitrogen has brought the world one step closer to creating a range of useful products -- from dyes to pharmaceuticals -- out of thin air.

'Black nitrogen'
In the periodic table of elements there is one golden rule for carbon, oxygen, and other light elements.

A deep dive into better understanding nitrogen impacts
This special issue presents a selection of 13 papers that advance our understanding of cascading consequences of reactive nitrogen species along their emission, transport, deposition, and the impacts in the atmosphere.

How does an increase in nitrogen application affect grasslands?
The 'PaNDiv' experiment, established by researchers of the University of Bern on a 3000 m2 field site, is the largest biodiversity-ecosystem functioning experiment in Switzerland and aims to better understand how increases in nitrogen affect grasslands.

Reducing reliance on nitrogen fertilizers with biological nitrogen fixation
Crop yields have increased substantially over the past decades, occurring alongside the increasing use of nitrogen fertilizer.

Flushing nitrogen from seawater-based toilets
With about half the world's population living close to the coast, using seawater to flush toilets could be possible with a salt-tolerant bacterium.

We must wake up to devastating impact of nitrogen, say scientists
More than 150 top international scientists are calling on the world to take urgent action on nitrogen pollution, to tackle the widespread harm it is causing to humans, wildlife and the planet.

Read More: Nitrogen News and Nitrogen Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.