Winner of the Royal Academy of Engineering’s biennial prize for materials engineering Graham Hutchings shares his personal research journey, when a career-long ‘love affair’ with gold led to pioneering advances in the field of catalysis.
Since the age of 11 I have always wanted to be a chemist. I saw the distillation of water demonstrated at my school and I was fascinated. I saved my pocket money for months to be able to buy some flasks and tubing so I could do the experiment at home. When I did finally explore water distillation in my kitchen, I didn’t get it right and it blew up. I was then thoroughly hooked.
After my PhD in biological chemistry from UCL, I joined ICI on Teesside as a research chemist and this is where I was introduced to the importance of chemical engineering. I was researching new catalysts for butane oxidation to maleic anhydride and collaborating with a chemical engineer.
We designed a wholly new process with a new catalyst, but ICI refused to tak e the work to the pilot plant stage. I was exceptionally unhappy with this outcome, and I asked to be seconded to Oil Works in Billingham. Over the three years I enjoyed production support improving olefin carbonylation and eventually became a plant manager where I became familiar with chemical engineering on a large scale.
My time at Oil Works ended in 1981 and this coincided with a recession in the UK. ICI then seconded me to AECI Ltd Modderfontein in South Africa, just outside Johannesburg. In 1982 I visited AECI’s Midland Factory in Sasolburg and they showed me their vinyl chloride plant for acetylene hydrochlorination that used a highly polluting mercury catalyst.
I was shocked that mercury was being used and even more shocked when I saw it was everywhere both inside the vessels and on the ground around the plant. They asked me to find a better catalyst, and this is when my neverending scientific love affair with gold started.
There is a saying that half a day in the library can save half a year in the labor atory. I searched the literature on catalysts for acetylene hydrochlorination and found a paper where over 30 supported metal chlorides had been tested as catalysts.
It was a rare wet Saturday in Johannesburg in September; in those days the TV there didn’t start until 5pm. I was bored and so I decided to read the paper on acetylene hydrochlorination. The author had tried to correlate the acetylene conversion with the electron affinity of the metal cation, which is a single electron process. But this clearly didn’t work. I concluded the reaction involved two electron transfers and hence the standard electrode potential would be better for a correlation. This worked and gave a really clear positive link between acetylene conversion and the standard electrode potential.
This was the eureka moment. Gold has the highest electrode potential but had not been tested. So, I predicted that gold would be the best catalyst for this reaction and then I demonstrated that it was indeed true; the prediction proved correct. AECI did try to scale up the discovery, but I left the company in 1984 to start my academic career, initially at the University of Witwatersrand and in 1987 I moved to Liverpool University.
We now fast forward to 2007 and at this stage my work with gold was largely forgotten, even by myself. I was now a professor of chemistry at Cardiff University and my first PhD student Pete Johnston, who worked for Johnson Matthey, wanted us to explore gold catalysis again as the company had acquired the rights to the gold work I had done in AECI.
This started a collaboration that persists to this day, and we have designed improved gold catalysts. Initially we had to create a catalyst that could be scaled up for commercial production.
For this we had to make sure the catalyst, which is gold supported on a high area carbon, would comprise minimal amounts of gold and used water as a solvent during the prepar ation.
Innovations made by Pete ensured this was achieved. Following pilot plant and full commercial trials, Johnson Matthey built a factory in Shanghai to make the catalysts at scale and the gold catalyst is now commercially operated in several plants in China.
As a result of the gold catalyst being available for acetylene hydrochlorination, China ratified the Minamata Convention in 2013. In 2017 the Minamata Convention became international law, and this seeks to ban all uses of mercury in any application globally. So my eureka moment has led to gold becoming a commercialised catalyst that in turn has led to a change in international law.
They asked me to find a better catalyst, and this is when my neverending scientific love affair with gold started
Today, I am still fascinated by gold as a catalyst, and I work closely with Johnson Matthey on understanding the fundamental nature of gold as a catalyst for acetylene hydrochlorination. However, I have extended the use of gold as a catalyst in other reactions and applications.
One of the recent discoveries that excites me the most today is the use of gold palladium alloy catalysts for the production of dilute hydrogen peroxide in water from the direct reaction of very dilute hydrogen with air.
This enables disinfection of water, and we have shown that we can remove pathogens such as bacteria and viruses. I am currently aiming to scale up this process as it has the potential to replace chlorination in the primary disinfection of water.
I have had a really rewarding career that has involved positions in industry and academia that has allowed me to enjoy both chemistry and chemical engineering. But it is the discovery of catalysis by gold that gives me the greatest pleasure. After all, gold is a beautiful and alluring metal.
- Regius professor of chemistry at the University of Cardiff Graham Hutchings CBE FREng FRS is the recipient of this year’s Royal Academy of Engineering Armourers and Brasiers Company Prize
Making a difference
Award sponsor and winner are both invested in impactful science
The Royal Academy of Engineering’s RAEng Armourers and Brasiers Company Prize is awarded to individuals in the UK for achieving excellence in materials engineering through novel materials science and technology in apractical engineering context. A cash prize of £2,000 is made to the winner.
Established with support from the Worshipful Company of Armourers and Brasiers, which provides a £2,000 cash award, the prize is presented every two years.
The company was founded as a guild mor e than seven centuries ago in 1322 to oversee the production of armour in England. Today, its main pur pose is the promotion of materials science via charitable donations, and it ranks as one of the largest private sponsors in the sector.
The University of Cardiff noted t hat, following the successful rollout of award winner professor Hutchings’ mercury-free catalyst, China ratified the Minamata Convention in 2013 which later was written into international law “signalling the end of the use of mercury in all applications globally”.
