The Catalyst Review March 2020 - 17

EXPERIMENTAL
It is well known that natural enzymes can efficiently degrade organic pollutants, although the range of applications is limited due to
their ease of deactivation, high cost and unrecyclable nature. On the other hand, nanozymes, as reactive oxygen species generators,
are ideal substitutes when it comes to degradation of organic pollutants because they offer high catalytic efficiencies, low costs, and
they can be recycled. Single-atom-containing nanozymes (SAzymes) have demonstrated great potential in the degradation of organic
pollutants. Compared with conventional nanozymes, single-atom-containing nanozymes demonstrate higher catalytic activities
because of their atomically dispersed MNx active sites.
After presenting numerous examples, the authors go on to identify the critical issues which will dictate the future development of
advanced nanozymes at the atomic scale, namely: precise regulation of the intrinsic active sites within SAzymes; the selectivity of
SAzymes; improvement of the metal loading of SAzymes; diversity of SAzymes; a mechanistic study of SAzymes; and new applications
of SAzymes. Source: Jiao L, Yan H, Wu Y, et al. (2020). Angew.Chem.Int.Ed. 59: 2565-2576.
Energy Researchers Invent Error-Free Catalysts...
A team of researchers from the University of Minnesota, University of Massachusetts Amherst, University of Delaware, and
University of California Santa Barbara have invented oscillating catalyst technology that can accelerate chemical reactions without
side reactions or chemical errors. Researchers at the Catalysis Center for Energy Innovation funded by the U.S. Department of Energy
(DOE) had a breakthrough when they realized they could design a new class of catalysts that greatly accelerated the primary surface
reactions using waves. When the applied wave frequency and amplitude match up with characteristics of the primary chemistry, then
that reaction becomes thousands of times faster than all other side reactions. The catalyst at these wave conditions essentially stops
making any errors to side products. "A molecule on a surface can go down several energy pathways, but the oscillating catalyst can
almost completely control which pathway the molecule selects, including preventing molecules from moving along undesired energy
conduits on the catalyst surface," said Alex Ardagh, the first author of the research paper and a postdoctoral research scholar at the
University of Minnesota. "The transition from conventional to dynamic catalysts will be as big as the change from direct to alternating
current electricity," said Professor Dionisios Vlachos, a professor at the University of Delaware and director of the Catalysis Center
for Energy Innovation. "This has the potential to completely change the way we manufacture almost all of our most basic chemicals,
materials, and fuels." Source: Science Daily, 3/4/2020.
Platinum Makes PVC Production Greener and Cheaper...
A single-atom platinum catalyst could replace the highly toxic mercury one used to synthesise the ingredient to produce PVC. The
new platinum catalyst is twice as efficient than the one used by industry oil, could cut mercury pollution and should be suitable
for scaling-up. In order to find a more environmentally friendly solution, researchers have explored other catalysts, particularly
gold and ruthenium supported on activated carbon. However, 'Metal-based catalysts suffer from deactivation, mainly due to the
reduction of the active metal sites due to sintering and fouling,'
explains Javier Pérez-Ramírez at ETH Zurich, who led the study. The
team decided to explore platinum as an alternative. 'We deposit
the platinum impregnating activated carbon in an aqueous solution
of chloroplatinic acid,' Pérez-Ramírez says. Platinum atoms stay
anchored to the carbon's pores, and the catalyst was then activated
by heating it. Using similar metal loadings and reaction conditions
described in the literature for gold catalysts, Pérez-Ramírez's team
managed to double the efficiency of the process. 'Considering that
platinum is currently 40% cheaper than gold and the low metal
loadings we use, this process should be very attractive to the
chemical industry,' he points out. To find the best platinum catalyst,
the team modified the synthetic conditions to yield different metal
nanostructures - from single atoms to nanoparticles - and carbonbased supports, and probed their performance using both experiments and theory. Both Tao Zhang, an expert in new materials for
catalysis working at the Dalian Institute of Chemical Physics of the Chinese Academy of Sciences and Graham Hutchings, a catalysis
expert at the University of Cardiff, UK think that the new process is far from finding an industrial application, as researchers have
only demonstrated its stability for 70 hours. But Pérez-Ramírez and his team remain optimistic and believe a pilot plant trial for this
platinum-based process 'seems well feasible'. Source: Chemistry World, 3/2/2020.

The Catalyst Review

March 2020

The Catalyst Review March 2020

Table of Contents for the Digital Edition of The Catalyst Review March 2020