Greenhouse Gas CO2 to Gasoline
Carbon dioxide (CO2), a major greenhouse gas, is considered the primary culprit in global warming. In recent years, countries have been striving to reduce CO2 emissions due to the impact of carbon emission policies. Petrol is one of the most widely used fuels in the world. With the development of modern society, petrol has not only become essential for a country’s production and daily life but also a daily necessity for many ordinary people. One is a greenhouse gas that contributes to climate warming, while the other is a valuable energy source on which people increasingly rely. Although these two may seem unrelated, scientists have found them to be inseparably linked.
In 2017, a team of researchers led by Sun Jian and Ge Qingjie from the Dalian Institute of Chemical Engineering, Chinese Academy of Sciences (DIC), discovered a new process for the efficient conversion of CO2. By designing a novel multifunctional composite catalyst, they achieved the first direct hydrogenation of CO2 to produce high-octane gasoline. The research results were published in the British journal Nature Communications on May 2, and the related process and catalytic materials have been patented. This work has been hailed by peers as “a breakthrough in the field of CO2 catalytic conversion.”
In nature, plants absorb CO2 from the air and convert it into organic matter and oxygen through photosynthesis, a slow process that has inspired chemists to explore chemical recycling of CO2. This would also reduce dependence on traditional fossil energy sources.
However, the activation and selective conversion of CO2 remain major challenges. Compared to its more reactive counterpart, carbon monoxide (CO), CO2 molecules are very stable and difficult to activate. Traditional methods like the Fischer-Tropsch process often result in small molecules such as methane, methanol, and formic acid rather than long-chain liquid hydrocarbon fuels, making it difficult to produce gasoline directly.
To address these challenges, the research team creatively designed an efficient and stable multifunctional composite catalyst. Through the synergistic catalysis of multiple active sites, the catalyst achieved low selectivity for methane and carbon monoxide under near-industrial production conditions, with 78% selectivity for gasoline fraction hydrocarbons among the hydrocarbon products. This significantly exceeds results reported in previous literature. Furthermore, the gasoline fractions were primarily composed of high-octane isoparaffins and aromatics, meeting the composition requirements of the national V standard for benzene, aromatics, and olefins.
The catalyst also demonstrated good stability, capable of operating continuously for more than 1,000 hours, indicating its potential for practical application. Unlike conventional catalysts, this catalyst contains three compatible and complementary active sites (Fe3O4, Fe5C2, and acidic sites).
The CO2 molecule is converted in a ‘three-step’ tandem process via the carefully constructed three-component active site. First, CO2 is reduced to CO through an inverse water-gas shift reaction on the Fe3O4 active site. The resulting CO is then converted to an alpha-olefin via a Fischer-Tropsch reaction on the Fe5C2 active site. Finally, the olefin intermediate migrates to the acidic site on the molecular sieve, where it undergoes oligomerization, isomerization, and aromatization to selectively produce gasoline distillate hydrocarbons.
The precise control of the structure and spatial arrangement of these three active sites is key to achieving the hydrogenation of CO2 into gasoline. This technology not only opens up new avenues for the study of CO2 hydrogenation to liquid fuels but also provides innovative possibilities for utilizing intermittent renewable energy sources (wind, solar, water, etc.). In addition to reducing CO2 emissions, this new process offers significant economic benefits.
Industrial Mass Production
According to a report in China News on March 4, the Dalian Institute of Chemical Physics of the Chinese Academy of Sciences (DICP) announced that the world’s first pilot plant for the hydrogenation of carbon dioxide to gasoline, with an annual production capacity of 1,000 tons, has been successfully developed in collaboration with Zhuhai Fusheng Energy Technology Co.
The team has been working on the industrialization of this technology since 2017, and in 2020, they completed the construction of a 1,000-ton pilot plant in Zoucheng Industrial Park, Shandong Province. Since then, they have conducted various tests, including commissioning, formal operation, and optimization of industrial data.
In October 2021, the China Petroleum and Chemical Industry Federation organized an on-site assessment of the plant. The evaluation revealed that the unit had significantly reduced the consumption of raw hydrogen and carbon dioxide, maintained low overall process energy consumption, produced environmentally friendly and clean gasoline, and met the unit performance and output targets. A third-party test found that the gasoline produced had an octane number exceeding 90, with a distillation range and composition compliant with National VI standards.
On March 4, 2022, the technology passed another evaluation by the organization’s scientific and technological achievements committee in Shanghai. Experts on the evaluation panel unanimously concluded that the CO2 hydrogenation to gasoline technology was the first of its kind in the world, featuring fully independent intellectual property rights and representing a globally leading achievement.
Surprising Highlights
The catalyst used in this process is relatively simple to prepare, and the raw materials are inexpensive: FeCl3, FeCl2, NaOH, and a common molecular sieve. This makes it much more cost-effective compared to the sophisticated catalysts typically discussed in scientific literature. The team has also proposed mechanisms by which all three reaction steps can be fine-tuned by adjusting the catalyst composition. In the future, better selectivity could be achieved with the use of suitable molecular sieves, potentially enabling the synthesis of other valuable products.
However, the performance of this material does not fully live up to the initial high expectations, and the conversion figures for H2/CO2=3 are not particularly impressive. Nevertheless, its application value is undeniable. Notably, the selective performance for C5-C11 products is maintained between 70% and 80%, with a stable fractionated product composition. The system also demonstrates long-term stability, meeting the basic requirements for industrial applications.
The most significant contribution of this research lies in its practical application. While much of the current CO2 reduction research remains focused on laboratory settings, often using precious metals to achieve ultimate efficiencies, this study takes a different approach. Instead of maximizing efficiency at any cost, it employs a relatively inexpensive catalyst. This paper returns to the core of CO2 reduction technology by achieving reasonable conversion and selectivity under industrial conditions.
The Significance of CO2 Hydrogenation to Gasoline
Many people might wonder why we would convert CO2 into gasoline, only for the gasoline to be burned and turned back into CO2. It may seem like a lot of effort to convert things back and forth, with the end result being the same CO2, making it appear as if a lot of energy is wasted for nothing.
To be honest, that’s what I thought when I first approached this subject. However, as my research progressed, I realized that this process actually makes a lot of sense.
1. Energy Storage.
There are many regions around the world where wind and solar power are highly suitable for development. However, wind and solar energy are intermittent and unstable, making them less ideal for direct grid integration. The energy required for converting CO2 into gasoline can be derived from these renewable sources. In this context, wind, solar, and industrial waste electricity—which are not easily utilized directly—can be used to power this reaction. This point is also mentioned in the paper.
Although the process of converting CO2 and hydrogen into gasoline is inherently inefficient, when viewed within this context of absorbing excess electricity, its feasibility improves upon industrialization. This energy conversion route becomes somewhat analogous to a peaking power source in the grid, such as a pumped-storage power station, where low-cost electricity during off-peak times is converted to more valuable electricity during peak demand. From the perspective of the power station alone, this might not be cost-effective, but when considering the overall grid load and peak-valley differences, it becomes economically viable.
On a larger scale, the industrial chain of wind power + carbon capture + CO2 hydrogenation to gasoline is valid. If this technology, which allows us to convert available water and CO2 into gasoline, can be realized, then every solar and wind power station could effectively become an oil field.
2.Reduction in Fossil Fuel Exploitation:
The CO2-to-gasoline-to-CO2 cycle keeps CO2 within the carbon cycle, thereby reducing the need for exploiting existing fossil energy sources. At the same time, this process can satisfy a portion (albeit a small portion) of the energy demand.
3.Application in Specific Situations:
In certain scenarios, the conversion of CO2 is particularly necessary. For example, in confined environments like nuclear submarines, where CO2 must be managed, it’s possible to convert CO2 with peroxides to produce oxygen. With emerging technologies that allow CO2 to be converted into methanol or even gasoline, converting CO2 into fuel becomes a practical solution. In such cases, where CO2 must be converted, the cost becomes a secondary concern.
