On December 24, 2010, experts from the Ministry of Science and Technology organized an inspection and acceptance of the State Key Laboratory of Coal Liquefaction and Coal Chemical Engineering in Shanghai. It is understood that the State Key Laboratory of Coal Liquefaction and Coal Chemical Industry will provide effective technical support for the implementation of China's coal clean utilization and energy diversification development strategy.

From the current point of view, although China's coal liquefaction technology has been correspondingly developed, at the same time, the efficient utilization of coal liquefaction residues has become increasingly prominent and has become a key issue for coal liquefaction. Coal liquefaction residue is a high-carbon, high-ash, and high-* material consisting mainly of unconverted coal, inorganic minerals, and coal liquefaction catalysts. In the process of coal liquefaction, about 30% of the liquefied coal is produced. The residue of coal liquefaction has economic value. How is its application in China? In what ways can we efficiently use coal liquefaction residues? With these questions, the reporter interviewed Wei Xianyong, a professor at China University of Mining and Technology.

Coal liquefaction residue is more profitable than “coal oil”

China Energy News: At the “China Clean Coal 2010 Conference” held earlier, you publicly stated that “The profitability of coal indirect liquefaction lies in the production of value-added chemicals, rather than 'coal oil' itself,” Describe the relevant circumstances in detail?

Wei Xianyong: In the decades since the Second World War, South Africa has been practicing a racist system. As a result, they have been punished by the international community, including the oil embargo. In order to get out of this predicament, South Africa can only use its rich coal resources to solve energy problems. With the strong support of the country, after decades of efforts, South Africa’s coal indirect liquefaction technology is at the leading level in the world.

If coal liquefaction only obtains liquid fuel, the so-called "coal-to-oil", it is not worth the candle. The organic matter in coal is mainly composed of macromolecules rich in condensed aromatic rings (editor's note: condensing aromatic rings are similar to graphite structures, carbon atoms are on the same plane, forming a planar network structure). In theory, the destruction of condensed aromatic rings requires higher energy. The indirect coal liquefaction first transforms the relatively stable macromolecules into the smallest molecules under the action of high temperature and gasification agent, and then synthesizes the small molecules into larger molecules, thus taking a detour and paying a great price. Only those chemicals with high added value can make up for the price they pay. South Africa uses synthetic gas as raw material to synthesize a series of high value-added organic chemicals using a carbon chemical method to compensate for the loss of “coal to oil”.

The utilization of coal liquefaction residues has not yet been applied. China Energy News: What is the current situation of coal liquefaction residues in China?

Wei Xianyong: To date, research on the utilization of coal liquefaction residues in China has involved gasification, the preparation of additives for road-building asphalt, and direct distillation or the capture of light oil products through catalytic hydrogenation, but none have entered the practical application stage.

Coal accounts for 70% of China's energy consumption while coal accounts for less than 30% of global energy consumption. Thousands of coal miners are killed each year in China; coal gangue accumulation and land collapse caused by coal mining occupy a large amount of arable land; the coal mining process causes serious damage to the surface and groundwater, which intensifies the shortage of water resources in China; Emissions of gas also exacerbate the greenhouse effect; the environmental pollution caused by burning coal is even more alarming. Therefore, the state should vigorously develop non-fossil energy and should change the unfavorable situation of using coal as the main energy source as soon as possible.

I believe that the efficient use of coal resources must be clean, limited, and highly value-added. The core is high value-added use. For a long time, China has unilaterally emphasized the so-called "clean coal technology" and neglected the use of high value-added coal resources. It is worth noting that most of the coal chemical industries launched in recent years in China are in a serious state of loss. China cannot continue to consume a large amount of resources and destroy the environment in exchange for limited economic development. Abandoning the traditional coal chemical industry and the so-called “modern coal chemical industry”, vigorously developing fine coal chemical industry, and using a small amount of coal to create huge economic benefits should be a major measure for China’s implementation of the scientific development concept and the real transformation of the economic structure.

Therefore, full use of modern science and technology, understand the composition of coal at the molecular level, and build a theoretical system of molecular coal chemistry; develop targeted coal and its derivatives as high value-added organic chemicals and high-end high-performance carbon under mild conditions Materials (especially carbon fiber), eventually forming the industrial chain of fine coal chemical industry has become our goal. Fine coal chemical industry should be an important part of China's strategic emerging industries.

Fine coal chemical industry chain is the future direction of development China Energy News: What is the positive significance of coal liquefaction residue utilization?

Wei Xianyong: The coal liquefaction residue is the residue obtained by flash evaporation during the direct liquefaction of coal. According to our understanding, the current coal liquefaction residue produced by the Shenhua direct liquefaction demonstration project is mainly used for combustion and power generation. The content of * in the coal liquefaction residue exceeds 2%, and the pollution from combustion and power generation is serious.

Many researchers at home and abroad mistakenly believe that the coal liquefaction residue is a mixture of unreacted coal and catalyst. In fact, most of the organic matter in coal cannot retain its original composition after undergoing catalytic hydrocracking and hydrogenation above 450 degrees Celsius. We extracted the raw coal and its liquefaction residue from SHENFU using carbon dioxide and methanol, respectively. We found that the extraction rate of raw coal was negligible, and the extraction rates of liquefaction residues in the two solvents reached 85% and 41%, respectively, for the victory lignite and its The extraction of liquefaction residues also gave similar results. This shows that in terms of organic matter, the composition of coal and its liquefaction residue is very different. Coal itself is very valuable, and it has to pay a great price for hydrogenation and liquefaction. The liquefaction residue obtained should be more valuable, and it is a pity to use it for combustion and power generation.

Regardless of whether it is from the viewpoint of improving the economic efficiency of coal liquefaction, or from the perspective of resource utilization and environmental protection, it is necessary to achieve efficient utilization of coal liquefaction residues. To achieve the directional transformation under mild conditions, through the fine processing of intermediate products into high value-added end products, the formation of fine coal chemical industry chain, which is also an important manifestation of China's development of circular economy.

China Energy News: What are the prospects of using the coal liquefaction residue industry?

Wei Xianyong: According to our research, coal liquefaction residues can be prepared through the subsequent processing of many high-performance carbon materials.

For example, for the preparation of needle coke can be used as a raw material for the production of ultra-high power electrode, promote the development of the iron and steel industry; for the preparation of carbon microspheres, can be used as a catalyst carrier, high-performance liquid chromatography stationary phase and lithium ion battery anode material. More important is the preparation of high-end high-performance carbon fiber. High-performance carbon fiber can be used for aircraft main wing, empennage, body and brake pads; rocket boosters, protective hoods and hoods; artificial satellites, spacecrafts, launch vehicles and shells; wind turbine impeller, sports The equipment, the bodies of high-speed trains, the shells and chassis of cars, and so on, are urgently needed materials for the development of national defense and many civilian industries in China. More than 90% of the world's carbon fiber raw materials are expensive polyacrylonitrile, and 2.5 tons of polyacrylonitrile can produce 1 ton of carbon fiber, and the discharged hydrocyanic acid seriously pollutes the environment.

In recent years, China has only achieved large-scale production of T300 carbon fiber, lagging behind Japan for nearly 40 years. We are pleased to learn that China has successfully developed a J-20 fighter that rivals the latest foreign fighters and achieved a major leap in aviation technology. The use of coal liquefied oil for the production of high-performance jet fuel, and the use of coal liquefaction residues as raw materials to produce high-end high-performance carbon fibers can provide important support for the development of mass production of more sophisticated fighter jets in China.

In theory, compared with polyacrylonitrile as raw material, high-concentration aromatics can be used as raw materials to prepare higher-performance carbon fibers. The key is how to cut the coal liquefaction residue into a narrow fraction and completely remove the inorganic matter. Our research group has long been engaged in the solvent extraction of coal and its derivatives and the analysis of extracts. We have developed an experimental system for the fine separation of coal tar and have mastered the technology of cutting heavy organic mixtures into narrow fractions by solvent extraction. The coal tars obtained are used. Asphalt successfully prepared filament carbon fiber. Last year, our research group and Zaozhuang Mining Group successfully established a pilot plant for the extraction and separation of coal tar, laying a solid foundation for large-scale extraction of high-quality high-performance carbon fibers such as coal tar and coal liquefaction residues and other heavy organic mixtures. .

At present, the coal liquefaction residue is considered to be a difficult-to-treat by-product and there is no mature technology in the country. However, as mentioned before, the use of coal liquefaction residues as raw materials through fine processing can lead to China’s development of defense and many civilian industries urgently needed materials, which will play an important role in supporting China’s national defense and economic development. Although the current utilization of residue is not industrialized, our capital investment is far lower than its output value. Therefore, the utilization value of coal liquefaction residues is higher than that of liquid fuels, and its prospects are also very considerable.