My fascination with gold began thirty years ago.
I was working at African Explosives and Chemicals Ltd in South Africa. I was asked to come up with a better catalyst for a process that makes vinyl chloride monomer from coal-based raw materials. The previous catalyst was mercury, which has significant environmental consequences.
As always, the best place to start was to look at what others had done before. I found a publication with some superb data. When I analysed the numbers I found a correlation that predicted gold would be the best catalyst. It appeared counter-intuitive; how could gold be the best when it is the most noble metal? Unperturbed, I carried out key experiments that showed gold was indeed the most stable catalyst for this important reaction.
Gold is now known worldwide as a very exciting catalyst. Work by myself and Masatake Haruta opened up this field, with our 1985 independent studies viewed as laying the foundation. Since then there has been an explosion of interest in gold catalysis with thousands of papers and patents showing the new intricacies of catalysis by gold.
Johnson Matthey picked up on this work due to renewed interest in the mercury-catalysed process, which is based on the availability of inexpensive coal in Asia. Today, around 20 million tons of vinyl chloride monomer are produced from the coal-based route, consuming over 60% of the mercury mined each year. This is not sustainable in terms of both mercury availability and the high levels of pollution resulting from its use.
My team at Cardiff University has worked with Johnson Matthey as they commercialise the gold catalyst. This will be the first time in about 50 years that a complete change in catalyst formulation is being evaluated for the production of a bulk chemical, which is something I am particularly proud of – especially as it alleviates the problems associated with mercury pollution.
At the Cardiff Catalysis Institute we have pioneered the use of gold as a catalyst in many reactions. We recently teamed up with the Max Planck Society in Germany as part of MAXNET Energy, in which we aim to study how small nanoparticles can function as even better catalysts.
Although it has taken over 30 years to get to this point, I am really excited that my original prediction has influenced chemistry worldwide. There is always something new to find out, and I feel lucky to be part of this discovery process.
One of our key ideas is to take catalysis into contact more directly with society. An example is the availability of clean water, a real problem in the developing world and arid regions which are becoming more prevalent through climate change. We are using gold catalysis as a means of purifying water, offering a realm of exciting possibilities. Hopefully, it won't take three decades to become a reality.