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If you asked someone who discovered catalysis, most people
would answer with ‘what’s catalysis?’!
Well, catalysis is a chemical process that’s critical to our modern lives.
It happens in factories, cars, oh, and also inside every living thing.
Discovering how it all worked back in the late 18th Century wasn’t an easy feat,
but Elizabeth Fulhame was up for the challenge.
Most chemistry students learn that catalysis was
discovered in 1835 by Jöns Jacob Berzelius.
And although he certainly gave a name to the process, the surprising chemical
behavior was actually documented some 40 years earlier by a particularly
strong-minded scientist named Elizabeth Fulhame.
But before we get into that, let’s set some foundations first.
Chemical reactions are happening all around us, all the time.
But all reactions need some energy to get
them started, known as activation energy.
Just like you need to summon a little extra energy to
get out of bed before you can go to work!
But if reactions need some help to go over that hump, there are substances,
called catalysts, that allow reactions to get around that activation energy,
so they can happen quicker, and at lower temperatures, than they normally would.
In most cases, catalysts work by providing a
surface for reaction ingredients to stick to while they react.
Once the molecules are stuck to the catalyst in the right positions, they are much
more likely to break and form bonds than if they were floating freely.
That means that even with all the chemistry happening around them,
the catalysts themselves aren’t used up.
And these catalysts are used pretty much everywhere.
They’re used to make about 80% of manufactured products,
and about 90% of industrial chemicals.
They’re in places like your car in the shape of a catalytic converter, where the
platinum surface helps to speed up the transformation of
super toxic gases to slightly less dangerous ones!
You also have catalysts inside your cells as protein catalysts, known as enzymes,
which are responsible for a bunch of things like
digestion, respiration, and cell repair.
Without them, all these processes would simply happen too slow for us to survive.
So catalysts are pretty important for a bunch of things, but discovering how they
worked in the late 18th Century was challenging.
And that’s where Elizabeth Fulhame comes in.
Although there isn’t much information about her, we do know that she had the time
and the means to pursue her interests as an experimental chemist, even though
this was a very much a male-dominated field at the time.
Her main mission was to find a way to dye cloth with gold.
Her idea was to deposit the metals, like gold, onto fabrics by starting out with a
metal-salt solution and then adding electrons to the
metal through a process called reduction.
Reduction happens when things like metal are exposed to a reducing agent, which
passes electrons into materials by oxidizing itself.
And Fulhame had hopes that it would help the metal bind to the cloth, after dipping
fabric in the solution, leaving behind lustrous metallic gold.
These kinds of interactions: the donation of electrons in reduction, and the loss of
them in oxidation, weren’t very well understood at the time. In fact, electrons
wouldn’t even be discovered for another hundred years!
So, when Elizabeth Fulhame published 14 years of her work in a single essay in
1794, she talked about it in terms of the chemicals involved: the metals, the
reducing agents like hydrogen, and oxidizing agents like oxygen.
In her essay, she reported some success in dying cloth with gold and also in
embellishing maps with gold and silver to mark cities and rivers
“as much as her finances allowed.”
But much of her essay is devoted to the hundreds of experiments she tried, which
have since been described by other chemists as both meticulous and tedious!
In these experiments, Elizabeth exposed metallic salts to various reducing agents,
like hydrogen or charcoal, under different conditions, trying to get them to react.
She exposed metals to reducing agents without using a solvent,
and to others she added solvents like water, ether, or alcohol.
And Elizabeth found that in many cases, high concentrations of water were needed
for reaction, as she saw little change in the experiments with small amounts of it.
More importantly, she was able to show that, with water in the mix,
the reduction of metals could be done at room temperature and colder.
Before then, people thought reducing metals could only be possible by heating
them, a lot, like in a furnace, to overcome the activation energy for the reduction.
Not only that, but the water still seemed to be there at the end of the reaction.
Elizabeth supposed that the water was broken down into its components, hydrogen
and oxygen, which were used up and regenerated over the course of the reaction,
likening it to a phoenix rising from the ashes.
But some turned the phoenix analogy against her, claiming that her theories were
as fanciful and fabulous as the phoenix itself.
However, the essay did contain the first real steps towards understanding catalysis.
Today we know that the metal reduction that
Fulhame was testing was being catalyzed by water.
The way water worked during the reaction was by
binding to the positive metal ions, so they could react and
combine easily with an electron from the reducing agent.
So, although her mechanism for water’s
involvement wasn’t quite right, her observations were spot on.
She was the first to describe catalysis, reduction,
oxidation, and equilibrium in a very modern sense.
When Berzelius came to the topic 40 years later, whether he knew about
her work or not, she had already helped to steer
the course of chemistry into familiar waters, way ahead of her time.
And catalysis is still something we’re learning about today.
The 2021 Nobel Prize in Chemistry was awarded for
the development of asymmetric organocatalysts, which,
although it sounds pretty advanced, it still relies on the foundations that
Elizabeth Fulhame uncovered more than 225 years ago.
And if you would like to keep exploring the other nuts and bolts of chemistry,
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