Hydrochloric acid boosts catalyst activity
Hydrochloric acid treatment improves catalysts for removing sulfur from
crude oil

Date:
August 25, 2020
Source:
Technical University of Munich (TUM)
Summary:
A research team 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.



FULL STORY ==========================================================================
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.


========================================================================== Story Source: Materials provided by
Technical_University_of_Munich_(TUM). Note: Content may be edited for
style and length.


========================================================================== Journal Reference:
1. Manuel F. Wagenhofer, Hui Shi, Oliver Y. Gutie'rrez, Andreas Jentys,
Johannes A. Lercher. Enhancing hydrogenation activity of Ni-Mo
sulfide hydrodesulfurization catalysts. Science Advances, 2020;
6 (19): eaax5331 DOI: 10.1126/sciadv.aax5331 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2020/08/200825110652.htm

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