Climate Change

30 Jul 2019

“Artificial Leaves”Turn Carbon Dioxide into Treasure

30 Jul 2019  by Nengyuanjie   

"The arrangement of carbon dioxide molecules is like two people holding hands tightly, a structure that makes carbon dioxide molecules very chemical inertia. All we have to do is force it to react with other substances under relatively mild conditions and turn it into treasure. " In the eyes of Professor Gong Jinlong, School of Chemical Engineering, Tianjin University, how to catalyze lazy carbon dioxide is the key to turn waste into treasure.

In the past three years, with the support of the national key R & D project, Gong Jinlong team has broken through the bottleneck problems such as high energy consumption, low efficiency and low added value of carbon dioxide resources by deeply studying the chemical catalytic conversion process of carbon dioxide, which has laid a scientific foundation for the wide promotion of its transformation and utilization technology, and the research results are in the leading level in the world.

Zero emission transformation: the most difficult and highest standard road is that a large amount of carbon dioxide is emitted into the atmosphere every day in the world. Efficient utilization of resources is not only an important way to achieve emission reduction, but also a worldwide problem. For a long time, the conventional carbon dioxide conversion technology used in China needs high temperature, high pressure and catalyst, and these conditions can not be obtained without the use of energy. In the context of coal-based energy in China, traditional technology will lead to additional carbon dioxide emissions. "you canundefinedt produce new carbon dioxide in the process of conversion, otherwise itundefineds going to make up for the west wall. It is cost-effective to convert to a general ledger and convert more than emissions. Our goal is zero emissions for net conversion of carbon dioxide. " The Gong Jinlong team chose the most difficult and standard path from the beginning.

The difficulty of carbon dioxide conversion lies in that its molecular structure is extremely stable, the transformation needs to inject high energy, and the path of carbon dioxide conversion is complex, there are many products after conversion, and the purity is not good. Therefore, the choice of conversion path and catalyst is very important.

Gong Jinlongundefineds team focused on solar energy. "Solar energy is an inexhaustible green energy source in nature." Gong Jinlong said they thought of photosynthesis in leaves, through which a leaf absorbs light energy, converts carbon dioxide and water into energy-rich organic matter, and releases oxygen. But the energy conversion efficiency of leaves is too low, only 0.1% ≤ 1%. "the catalyst we have to do is like an artificial leaf with an energy conversion efficiency of a hundred times that of an ordinary leaf." Using solar energy and artificial leaves to convert water and carbon dioxide into methanol, methane and other carbon-containing molecules efficiently under the action of catalyst, it can be reused as fuel directly.

Tens of thousands of experiments to realize the assumption of "artificial leaves" , it is necessary to establish a new type of carbon dioxide catalytic conversion reaction system and find a more efficient catalyst.

However, this groundbreaking research is really too cutting-edge. Recalling the original study, Gong Jinlong said with emotion: "our research completely started from scratch." The transition from 0 to 1 was an extraordinarily difficult trek.

First of all, the experimental equipment does not have ready-made commercial devices to buy, relying on the research team to explore the design and development. From drawing design, to the choice of materials, tools, to the final installation is done by the researchers themselves.

Secondly, the choice of which catalyst is more efficient, but also rely on groping to try, the failure of the experiment has almost become the norm. "although it has not been carefully counted, it is no exaggeration to say that we have carried out tens of thousands of experiments, failed, summed up, adjusted the scheme, and then carried out the experiment. Almost every day during that time, I worked around and over again. " Gong Jinlong recalled. In the research and development process, Gong Jinlong team also faces fierce competition from American and Japanese counterparts. Under this pressure and motivation, the teamundefineds researchers race against time every day.

Finally, after more than three years of research, they realized the efficient conversion of carbon dioxide under mild conditions by using green energy such as solar energy and hydrogen energy, and established a new way of "photocatalytic carbon dioxide reduction" and "carbon dioxide hydrogenation reduction", which opened up the green conversion channel from carbon dioxide to liquid fuels and high value-added chemicals. A new breakthrough in reducing carbon dioxide to methanol and other hydrocarbon fuels has been achieved. In the process of conversion, the yield of carbon-containing products is as high as 92.6%, and the selectivity of methanol is 53.6%, which reaches the leading level in the world. The related research results, as cover hot papers, are published in German Applied Chemistry, Energy and Environmental Science and other internationally renowned journals.

The efficiency of carbon dioxide mineralization is the highest level in the world. While the basic research is at the forefront, Gong Jinlong team is also committed to the practical application of carbon dioxide mineralization and transformation. Professor Gong Jinlong said humorously, "our research should not be so aloof and approachable." In view of the poor economy of carbon dioxide conversion process, this "approachable" study uses more efficient catalysts to prepare high value-added fine chemicals such as polycarbonate and titanium dioxide, which lays a foundation for the industrial application of carbon dioxide mineralization and transformation through the measures of "ionic liquid synergistic catalytic transformation" and "utilization of non-alkaline ore mineralization". Gong Jinlong said that at present, 20 million tons of steelmaking blast furnace slag containing titanium and aluminum can not be utilized every year in China. Their technology can efficiently recover titanium, aluminum and other metal elements while mineralization and immobilization of carbon dioxide, and the high purity titanium dioxide obtained in the mineralization process can be used in dye making, and the resource utilization of blast furnace slag can be fully utilized.

At present, the carbon dioxide mineralization efficiency of this technology has reached 200 kg / ton (non-alkaline ore), which is the highest level in the world. Today, the team is conducting an expanded experiment on the preparation of high purity titanium dioxide from 300 tons of titanium blast furnace slag a year.

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