The final part of our blog looks to the future, including introducing electrocatylists, which could give the potential game-changer of both generating electricity and producing fuels like petrol and diesel using naturally abundant substances. We also see how predicting a specific catalyst for any reaction will soon be within reach. It looks like the best days of the alchemist might still be ahead.
By Aditya Sengar, Research Associate in the Department of Bioengineering.
Ever since the industrial revolution the world has been in a crisis mode. We need more efficient and cleaner energy over the dirty fossil fuels we currently have. The science of catalysis has been challenging the energy sector by constantly developing processes that either reduce or abandon the usage of fossil fuels. It is unfortunate that the biggest bottlenecks for adaptation of such processes are political. The USA signing out of the Paris Agreement on climate change, and China’s increasing reliance on coal, do not help the cause. We have seen historically that man-made devastating events can be tackled when global powers work together in a timely manner. I remember as a child reading about the depleting ozone layer. The problem started in 1980s when it was realised that typical refrigerants, called chlorofluorocarbons (CFCs), used in our air-conditioners and refrigerators cause breakdown of ozone molecules making us vulnerable to harmful ultraviolet (UV) light from the sun. Global events like Montreal Protocol in 1987 and Kyoto Protocol in 1997 started a wave of cooperation among politicians. Scientists unleashed the power of catalysis by experimenting with different catalysts to find ways to produce variations of carbon, hydrogen, and chlorine that are ozone friendly. The plan worked and the usage of new refrigerants (hydrofluorocarbons- HFCs) have already brought the size of ozone hole at its minimum since 1982. Unfortunately, it turns out that these HFCs contribute to greenhouse gas emissions and countries are now working to replace HFCs with more environmentally friendly natural refrigerants.
The ozone story can be used to ask a bigger question: Wouldn’t it be remarkable to be able to generate electricity or produce useful chemicals like petrol, diesel, and ammonia using naturally abundant substances like water, carbon dioxide, and nitrogen rather than fossils? This is the exact question chemists are trying to solve with electrocatalysis. Let us dig a bit deeper into this.
Electrocatalysis: Existential crisis to the fossil fuel economy
Electrolysis uses an electric current to force a reaction to occur over a catalytic electrode. Under normal circumstances, this reaction would be extremely unlikely to occur. Consider hydrogen fuel cells. In the previous blog, we discussed how the hydrogen fuel cell economy is challenging the current electricity generation and distribution landscape. The only downside of hydrogen fuel cells is the usage of coal and natural gas to produce hydrogen. Using electrocatalysis, a water molecule is split using electricity, generally produced from a renewable source (wind, solar), to produce hydrogen and oxygen. In another instance, carbon dioxide from the atmosphere is reduced catalytically to form important products like methane (called green methane), hydrocarbons, carbon monoxide etc. The present research challenges mainly surround the choice of optimum catalyst and the ability to scale up a successful experiment on a lab scale to a commercial scale.
The challenge of finding the optimum catalyst
Certain metals and compounds have a natural tendency to increase reaction rates. Ironically, gold and silver, the metals that alchemists wanted to synthesize, have excellent catalytic properties. Finding the perfect catalyst, however, remains a challenge. Major research labs rely on spectroscopy methods like X-ray photoelectron spectroscopy (XPS) or Nuclear magnetic resonance spectroscopy (NMR) to determine catalyst dynamics during an ongoing reaction. The data is used to compare the catalyst dynamics from other samples to find the optimum catalyst. In a positive turn of events, the advent of supercomputers has been like a holy grail to catalyst science. With more processing power, scientists can model the catalyst dynamics on molecular levels and transform the information to something reaction engineers can understand. Computational techniques like Density Functional Theory (DFT), microkinetic modelling and kinetic Monte Carlo (kMC) are used together to predict catalyst properties and reaction dynamics a priori.
As computational power progresses, the dream of predicting a specific catalyst for any reaction will soon be within reach and will provide scientists to engage in public undertakings of world crisis at much earlier stages.
Conclusion
Catalysis as a science is almost 200 years old. The 20th century has seen an explosion of industrial use of catalysts spurred by major historic events like the world war, and the need to find energy replacement by countries. In 2020, the global catalyst market stands at a net worth of USD 35 billion and is expected to reach USD 48billion by 2027 with a 4.4% annual growth rate. It looks small but estimates show that catalysts are used in 90 percent of U.S. chemical manufacturing processes and to make more than 20 percent of all industrial products with a direct or indirect contribution of 30-40% on the world GDP. The industry produces 20% of the greenhouse gas emissions with cleaner options, like blue hydrogen (produced via natural gas), green hydrogen (produced via electrolysis) and green methane, already starting to penetrate the global markets. Processes like Fischer-Tropsch that still take coal as a feedstock to produce synthetic fuel are an active field of research with hopes to reduce the coal dependence by employing biomass as feedstocks. Catalyst industries have also grown hand in hand with the market for production of sustainable energy solutions. Biofuels, from modern day catalysts, are already available for retail consumption in the western world with hopes to enter the markets for consumers in the rest of the world soon. Electrocatalysis is also a budding research field that hopes to completely stop the usage of fossil fuels for energy generation.
Although, countries with natural resources have been self-sufficient with their energy production (Norway with hydroelectricity, Denmark with solar and wind energy), for the rest of the countries relying on oil or coal, catalysts might just be the alchemist’s gold that saves them from an impending energy crisis whilst addressing climate change concerns.