• Solving the plastic shortage with a new

    From ScienceDaily@1:317/3 to All on Thu Jul 8 21:30:34 2021
    Solving the plastic shortage with a new chemical catalyst

    Date:
    July 8, 2021
    Source:
    University of Michigan
    Summary:
    In a year that has already battered manufacturing supply chains,
    yet another shortage is complicating manufacturers' and consumers'
    lives: plastics, and the food packaging, automotive components,
    clothing, medical and lab equipment and countless other items that
    rely on them.



    FULL STORY ==========================================================================
    In a year that has already battered manufacturing supply chains, yet
    another shortage is complicating manufacturers' and consumers' lives:
    plastics, and the food packaging, automotive components, clothing,
    medical and lab equipment and countless other items that rely on them.


    ==========================================================================
    But a new chemical catalyst developed at the University of Michigan
    could enable the production of more of the feedstock for the world's second-most widely used plastic. The feedstock, propylene, is used to
    make the plastic polypropylene -- 8 million tons of it each year.

    The new catalyst, which can make propylene from natural gas, is at least
    10 times more efficient than current commercial catalysts. And it lasts
    10 times longer before needing regeneration. It is made of platinum and
    tin nanoparticles that are supported by a framework of silica.

    "Industry has shifted over the years from petroleum feedstocks to shale
    gas," said Suljo Linic, the Martin Lewis Perl Collegiate Professor of
    Chemical Engineering at U-M and senior author on a paper published in
    Science. "So there has been a push to find a way to efficiently produce propylene from propane, a component of shale gas. This catalyst achieves
    that objective." The secret to efficient 'non-oxidative dehydrogenation' Propylene has traditionally been produced at oil refineries in massive
    steam crackers that break down petroleum feedstock into lighter
    hydrocarbon molecules. But cracking shale gas to produce propylene has
    been inefficient.



    ==========================================================================
    The new catalyst can efficiently produce propylene -- a molecule
    with three carbon atoms and six hydrogens -- from propane, which
    has two additional hydrogens. It uses a process called non-oxidative dehydrogenation. One of the reasons current catalysts are inefficient is
    that they require adding hydrogen to the process. This approach does not.

    The key innovation of the new catalyst is how it uses silica as a support structure for the platinum and tin nanoparticles, rather than the alumina that's used in current catalysts. Alumina reacts with tin, causing it
    to separate from the platinum and break the catalyst down. Because the
    new catalyst holds off this reaction, it has a longer life.

    "Silica as support for platinum-tin nanoparticles has been tried before,
    but conventional synthesis techniques weren't precise enough to enable
    close interaction between platinum and tin," said Ali Hussain Motagamwala,
    U- M postdoctoral research fellow and first author on the paper.

    "We overcame this by first synthesizing a platinum-tin complex with
    excellent interaction. We then supported this complex onto silica to
    produce a very well- defined catalyst that is active, selective and stable during nonoxidative propane dehydrogenation." A key to commercialization
    will be finding a way to regenerate the catalyst after it becomes fouled
    by carbon. Even though current catalysts are short- lived, Linic says, the chemical industry has developed an intricate system that can regenerate
    the fouled catalyst quickly and efficiently. A similar system will need
    to be developed for the new catalyst.

    Stabilizing propylene supplies "Building the kinds of plants that would
    run this process on a commercial scale would be a massive investment,
    and for that reason, the chemical industry tends to move slowly,"
    Linic said. "This catalyst is very good, but regeneration is the next
    big question." While the catalyst is still in the research stage,
    it holds the possibility of bolstering the world's propylene supplies,
    which have been depleted by skyrocketing global demand, COVID-driven
    production issues and a series of hurricane-related shutdowns at Gulf
    Coast oil refineries that produce the chemical.

    The research was supported by the U.S. Department of Energy Rapid
    Manufacturing Institute (award number DE-EE0007888) and by the
    U.S. Department of Energy Office of Basic Energy Sciences, Division of
    Chemical Sciences (DE-SC0021008).

    ========================================================================== Story Source: Materials provided by University_of_Michigan. Note:
    Content may be edited for style and length.


    ========================================================================== Journal Reference:
    1. Ali Hussain Motagamwala, Rawan Almallahi, James Wortman, Valentina
    Omoze
    Igenegbai, Suljo Linic. Stable and selective catalysts for propane
    dehydrogenation operating at thermodynamic limit. Science, 2021
    DOI: 10.1126/science.abg7894 ==========================================================================

    Link to news story: https://www.sciencedaily.com/releases/2021/07/210708143853.htm

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