President of University of Science and Technology of China: Can black coal bring us green surprises?

Many environmental problems are related to energy, and energy is inseparable from chemistry. So from a chemist's perspective, what will the future energy world look like? In green and sustainable development, what can chemistry do? The most important thing here is the science of catalysis. We are all engaged in chemistry, and we are very proud of it. We have always said that chemistry is the central science, and we live in an era of chemistry. In the entire energy environment, what we have been doing in chemistry is actually these three elements.: One is carbon, one is hydrogen, and one is oxygen. Carbon combines with oxygen. If there is too much oxygen, it becomes carbon dioxide. ； The combination of carbon and hydrogen makes hydrocarbons, and hydrocarbons are our oils and chemicals. ； The combination of hydrogen and oxygen becomes water, or another form of water. This is basically what we do in chemistry. Catalysis is a very important field in chemistry. As you can see, how catalysis promotes the development of green economy must focus on these three aspects: One is the optimal utilization of fossil resources, that is, how can I make good use of fossil resources? ； The second thing is whether it is possible for us to utilize carbon dioxide ； The third thing, and what everyone is more concerned about now, is that hydrogen can be used as a fuel cell. How do we think about this? first take a look at us * * In the entire energy environment, what challenges have we encountered regarding green development?

1 "Lack of oil and gas", how to explore the huge potential of coal through catalysis? The proportion of the world's energy structure is about one-third coal, one-third oil, another one-third natural gas, and probably a third part renewable energy. But for China, the situation is different. And from the perspective of external dependence. For example, when I go to fill up a tank of gas now, about 70% is imported and 30% is produced in China. ； About 45% of natural gas is imported, and about 50% is produced by ourselves. China's energy intensity is very high. What does energy intensity mean? For a GDP (gross domestic product) of US$10,000, the energy consumed in China is not comparable to the energy consumed abroad. At the beginning of this century, our energy consumption was about 8-10 times that of Japan. In other words, if we produce a GDP (gross domestic product) of 10,000 US dollars, we consume, for example, 8 parts of coal, while the Japanese may consume 1 part of coal. So our efficiency is indeed very poor, and the burning of coal pollutes our air and water a lot. How will China develop? Judging from the data on China's external dependence on oil and natural gas from 2000 to 2018, the so-called dependence refers to how much do we need to import? In 2018, we imported about 45% of natural gas and our dependence on imported oil was about 70%. But how much oil do we develop per year now? The maximum output was probably less than 200 million tons. Now it is almost 190 million tons, but we need to use 600 million tons of this oil. We definitely won’t be able to develop so much in the future.

We will definitely not be able to develop so much in the future. Nature has its arrangement. The Middle East has more oil, while China has relatively more coal. In some coal mines, more than ten meters are filled with coal. It is piled in that place. We then use machines to dig it out and it becomes coal, and it is good coal. So for us in China, there is one thing that is very necessary and strategic, which is how to turn our existing resources, our coal, into the oil, natural gas or our chemicals that we have less. Americans don't do this because they have a lot of oil and natural gas, and they don't even need to use coal to do this. Do Europeans do it? Neither do Europeans. So in fact, this thing has very Chinese characteristics, and we must use this as a reserve for our strategy. But after it is finished, will it be immediately opened into a factory for mass production? This is not necessarily the case, it depends on the economic situation. If there is economic demand, I will use it. If there is no economic demand, I will not use it. But we must know how to turn coal into oil or chemicals. This is what we have been doing. I think there may be many of us here doing this, and the Chinese are the best at this. For example, in the area of ​​coal-to-liquids, our annual output in China is 160,000 tons, and we have done a lot of coal-to-liquids. Our largest coal-to-liquids factory in China is in Ningdong, Ningxia. The largest unit can produce 4 million tons of oil a year, which is a huge amount. Another thing China has done is to first turn coal into methanol, and then turn methanol into olefins.

So everyone is thinking, is it possible to directly use a catalyst to cut coal like scissors and turn it into what we need? As we all know, in petroleum refining, we use catalysts to cut off the oil products and then produce what we need. So is it possible that one day this coal will also find a catalyst, or how to cut it off? Isn’t that what we need? In 1924, two Germans, one named Franz Fischer and the other Hans Toropsch, came up with this process and called it the "Fischer-Tropsch process". This has been the process for more than ninety years. “How is the Fischer-Tropsch process done? It uses water to react with carbon monoxide and turns into hydrogen plus carbon dioxide, which is a water-gas change reaction. Then use the hydrogen to remove the oxygen from the carbon monoxide and turn it into water. The carbon monoxide reacts with hydrogen to turn into CH2 (low-carbon olefin). So what are we doing now? One thing we have done in the past ten years is to use another oxide as a catalyst instead of using the Fischer-Tropsch reaction catalyst. Just use a catalyst to directly react the carbon monoxide with the oxygen and turn it into carbon dioxide. The carbon reacts with the hydrogen to turn into this thing. Then one advantage is that there is no need for water and there is no recycling. ； Another advantage is that the three-step reaction finally becomes one step.

The best in the world, for example, in making olefins, it has a selectivity of 58% for low-carbon hydrocarbons. Then we will use this reaction because it has high selectivity. It can achieve more than 90% selectivity of low-carbon hydrocarbons in one go. As you know, there is a big difference between 58% and 90%. After this incident came out, we not only made such a reaction, we further promoted this concept. It is actually a platform that can at least use less water, emit less carbon dioxide, and consume less energy, because this process is energy-saving, and its reaction selectivity is high. So this process is also a green process. Why do I say that catalysis can support green development? How to support this coordinated development? That is what we do, which is to support green development through catalysis in the coal chemical industry. Global warming has become an important obstacle restricting the sustainable development of human economy and society. Greenhouse gas emissions will cause the global average temperature to rise, trigger melting of ice caps, extreme weather and rising sea levels, endangering human survival. Carbon dioxide is the most important greenhouse gas today and one of the biggest challenges facing mankind. The United Nations has made many efforts specifically to reduce carbon dioxide emissions. However, in the eyes of scientists, in addition to being harmful, carbon dioxide is also a rich "carbon source". If it can be "turned into treasure" with the help of scientific and technological means, it will not only alleviate the greenhouse effect caused by carbon emissions, but also be recycled and become an ideal form of energy supplement. How to turn the culprit of the greenhouse effect into a resource for our sustainable development?

2. Can catalysis turn greenhouse gas carbon dioxide into waste? What is the greenhouse effect? When we were young, we bought popsicles in the countryside. The popsicle seller would put the popsicles in a box and cover it with a quilt. When someone came to buy them, they would take them away for a few cents each. I have always wondered why popsicles should be covered with quilts since I was a child. Aren’t popsicles afraid of heat? Wouldn't it be warmer if you covered yourself with a quilt? Because we usually have this impression, we only cover ourselves with quilts when it’s cold in winter. Why do we sell popsicles covered with quilts? I later learned that, in fact, the purpose of covering a quilt is to prevent heat from dissipating and achieve the effect of heat preservation. So now everyone thinks that when there is too much carbon dioxide, something like a quilt will be produced in our atmosphere, covering the earth. But where does the earth's energy come from? It comes from the sun. A large part of the sun's energy is emitted into the atmosphere through infrared light, so as to maintain the basic balance of the earth's temperature. So, if we put a "quilt" on the earth, no matter whether it is thick or thin, wouldn't it be difficult to dissipate the energy from the sun? Isn’t the earth’s temperature increasing? So according to this theory, carbon dioxide is a greenhouse gas.

The international community sat together to discuss, and everyone recognized that carbon dioxide is a greenhouse gas, which will have a great impact on the earth's temperature rise and the environment. Then everyone is considering limiting carbon dioxide emissions. Westerners say that we must first limit, control the total amount first, and reduce what should be reduced first. Therefore, whether it is the Paris Agreement or climate negotiations, China has played a big role in them. Finally, we in China believe that the West developed earlier, and the carbon dioxide in the atmosphere may have accumulated over hundreds or hundreds of years of emissions. Well, now that China is about to develop, and the West suddenly imposes restrictions, we will no longer be able to emit emissions. There was a time when planes flying to Europe were required to collect carbon taxes. If the carbon tax was not collected, the planes would not be allowed to land because the planes emitted carbon dioxide. So, if one day in the future the world says that carbon dioxide is a problem, and the Chinese emit one-third of the carbon dioxide, we must collect taxes from the Chinese, and we really have no way to solve it, right? Everyone is asking again, can I use energy but not emit carbon dioxide? But we know that as long as fossil energy is used, adding carbon to oxygen will always produce carbon dioxide. One ton of coal will emit more than two to three tons of carbon dioxide. Some people say that carbon dioxide comes from energy, so I should use less energy. But will it be a problem for development if I use less energy? We in China want to make a commitment to the international community that carbon dioxide emissions are related to development, but this does not mean that less carbon dioxide emissions will necessarily mean that development will be slower.

From this point of view, but what if there are not many renewable energy sources available now, and carbon dioxide has been emitted, or carbon dioxide will be emitted soon? The Americans came up with a way, called CCS, which stands for carbon dioxide capture and storage technology, which collects the produced carbon dioxide, purifies it and then compresses it. Haven’t we already opened so many coal mines? Can we eventually hide this compressed carbon dioxide in mines or in rocks? Others say to hide under the sea. The method used by Americans is called CCS (carbon dioxide capture and storage technology). It costs a lot of money, and everyone is doing it. Please judge, is it reliable to put compressed carbon dioxide under the rock formation or somewhere? Of course it would be great if it was well preserved. But what if there is an earthquake or some natural disaster? What is the key issue? It’s just that the cost is extremely high. How high is it? For example, the energy efficiency of our current highest power plants is about 50%. Half of the waste heat is dissipated, and the remaining half is used to generate electricity. If we use this method, the power generation efficiency will become 40% in the future, which means that 10% of the energy will be used to process carbon dioxide. So is this thing appropriate? But we are still researching it now, and no place is doing this on a large scale. But soon someone will ask, can we use carbon dioxide? What else is anyone doing recently? That is, after the co-conversion of carbon dioxide and methane in electrocatalytic conversion, it becomes the chemical methanol, and in the future it will become things like ethylene and ethanol. If in the future we can directly use electricity to put carbon dioxide on electrodes with water or methane to turn it into the chemicals we need, I think this process is still feasible.

Many people have wondered whether it would be possible to make a leaf in the future, because leaves turn water and carbon dioxide into the hydrocarbons we need through photosynthesis. So is it possible to use artificial leaves for direct transformation in the future? Others use a photoreactor to directly add carbon dioxide and water. When the light shines on the catalyst, we can obtain fuel and oil products. Is it possible for these to convert carbon dioxide in a renewable energy scenario? I think it is possible, but I don’t know when it will be realized. It depends on everyone working together to do this. I think everyone has a long way to go. This matter is scientifically feasible, but how to turn these things into a practical process requires everyone to spend a lot of effort to do it, so this is a beautiful vision. Humanity's pursuit of energy is endless, and various cutting-edge energy sources are performing their own trends, trying to occupy a dominant position in the future energy system. Hydrogen energy is one of them. It is called the ultimate energy source of the 21st century. In people's expectations, hydrogen energy is inexhaustible, clean and efficient, will not produce greenhouse gases such as carbon dioxide, and will not worry about the depletion of fossil energy.

Can catalysis help the hydrogen society arrive as soon as possible? Nowadays, society has been talking about hydrogen energy, as well as hydrogen economy and hydrogen society. They are all talking about such things. But we chemists need to make a judgment, what will hydrogen energy be like? What will happen in the future? Under what circumstances can we talk about hydrogen energy? Let’s see what hydrogen energy is all about. When the energy carbon reacts with oxygen, for example, when air is mixed with gasoline, diesel and other fuels, it will explode when it encounters a spark. Such an explosion will occur in the cylinder, producing high-temperature and high-pressure gas, pushing the piston to do work. This is how the internal combustion engine comes about. The efficiency of the energy it generates is about 30%, and the remaining 60% is lost. Carbon exists in nature, and we can dig it out, but it produces greenhouse gas—carbon dioxide. So you can see that nature is very balanced and fair, and some things will inevitably produce bad things accordingly.