Guarding the blue sky and white clouds - remember the key technology and industrial application projects of light rare earth-based integral honeycomb flue gas denitration catalyst

The research and development of environmentally friendly denitration catalysts has always been a major demand
for international environmental protection.
The project of "Key Technology and Industrial Application of Light Rare Earth-based Integral Honeycomb Flue Gas Denitration Catalyst" completed by Professor Shen Yuesong's team of Nanjing University of Technology and Shandong Tianjian Environmental Protection Technology Co.
, Ltd.
proposed and successfully developed a green and efficient denitration catalyst with light rare earth cerium oxide as the main active component, filling the gap of flue gas denitration and non-toxic catalyst technology at home and abroad, realizing large-scale industrial application, and adding economic benefits of 2.
45 billion yuan
in the past five years.
The project also recently won the first prize
of technical invention of the Chinese Chemical Industry Society.

Denitrification is the key to pollution reduction and carbon reduction

In order to win the "blue sky protection war" and achieve the "dual carbon" goal, the conversion of coal to gas has become an important measure
for pollution reduction and carbon reduction.
However, more nitrogen oxides
are produced during the coal-to-gas conversion process.
"Air pollution has thus begun to change from sulfuric acid haze to nitric acid haze, the task of denitration has become more prominent, and ultra-low emissions of nitrogen oxides have become a key problem
to be solved in the current energy-consuming industry.
" Shen Yuesong said that the key to flue gas denitration treatment lies in the application of
selective catalytic reduction and high-efficiency denitration catalysts.

At present, there are two denitration catalysts in China, precious metals and molecular sieves, but precious metal catalysts are often nearly one million yuan per cubic meter, and molecular sieve denitration catalysts are prone to ash plugging
.
In addition, the foreign vanadium-based denitration catalyst technology introduced in China in the early stage, although it partially alleviates the pollution of nitrogen oxides, but because its active component vanadium pentoxide is a water-soluble and highly toxic substance, it threatens environmental safety and is difficult to achieve green and sustainable development
.

Rare earth-based catalysts are introduced

"Rare earths have the characteristics
of high abundance and low price in China.
" Professor Zhu Shemin of Nanjing University of Technology said that the light rare earth waste residue produced during mining heavy rare earths, namely cerium oxide, stands out
for its environmentally friendly and strong redox characteristics.
"However, cerium oxide has shortcomings such as weak acidity, sulfur poisoning, poor high temperature hydrothermal stability and narrow activity window, and cannot be directly used to replace vanadium
pentoxide.
" Zhu Shemin said
.

After years of research, Shen Yuesong's team proposed and successfully developed a green and efficient denitration catalyst with light rare earth cerium oxide as the main active component, and realized the green and efficient denitration and large-scale industrial application of rare earth-based catalysts throughout the life cycle of rare earth-based catalysts by creating a new system of high-efficiency cerium-based composite oxide denitration catalysts, inventing the key preparation technology of integral honeycomb denitration catalysts and the application
and recycling technology of light rare earth-based catalysts.

According to Professor Chen Yingwen, a member of the project team, they created a new system of high-efficiency cerium-based composite oxide denitration catalyst, which improved the acidity of the solid surface of the catalyst, enhanced the resistance to water-sulfur poisoning and thermal stability by introducing co-catalytic elements such as zirconium, realized the environmental friendliness of the flue gas denitration catalyst, and opened up a new path
for the high value-added utilization of high-abundance light rare earth cerium oxide.
The new rare earth-based series catalysts have high denitration efficiency, wide active temperature and long service life, which are significantly better than commercial medium temperature vanadium-based catalysts
.

"Through chemical modification and nano-modification, we invented the key preparation technology of the overall honeycomb denitration catalyst, which solved the problem
that it is difficult to coexist with high activity and high strength of honeycomb catalyst.
" Wang Zhimin, a member of the project team and a professor-level senior engineer, introduced that they improved the strength and catalytic activity of the material, and increased the strength and hardness of the rare earth-based catalyst by 2~3 times
compared with the vanadium-based catalyst.
The results of engineering test operation show that the compressive strength of rare earth-based catalyst can reach at least 3 MPa, and it is still intact after 4 bursts, and the operation time is more than 5 years
.

In addition, the project team has also developed the application and recycling technology
of light rare earth-based catalysts.
They have developed a series of new regeneration processes and equipment such as negative pressure ash cleaning, ultrasonic water washing and active repair of deactivated catalysts, reducing the cost of secondary denitrification by 40%; It has invented new technologies such as the resource preparation of porous ceramic membrane catalysts from waste rare earth catalysts, titanium-based textile porcelain and catalytic cementation calcium carbide slag bricks, realizing the application and recycling of light rare earth-based catalysts and leading the green and sustainable development
of rare earth catalysts.

Industrial applications are highly beneficial

According to engineer Li Huiyuan, a member of the project team, in 2016, the rare earth-based denitration catalyst was designated as a substitute for vanadium-based denitration catalyst by the three ministries and commissions of the state, and the world's largest denitration catalyst production line has been built, and mass production has been achieved in Shandong Tianjian Environmental Protection Technology Co.
, Ltd.
and Inner Mongolia Seagate Environmental Protection Technology Co.
, Ltd.
, with a production capacity of 50,000 cubic meters per year
.
The project results have been applied to more than 280 enterprises across the country, including China Huaneng Group Co.
, Ltd.
and China Datang Group Co.
, Ltd.
, with new economic benefits of 2.
45 billion yuan in the past five years
.

It is reported that the project has successively obtained 34 invention patents, led the formulation of the national standard for rare earth SCR denitration catalyst, was selected as one of the top 100 international environmental protection technologies, major environmental protection technologies encouraged by the state and the Ministry of Industry and Information Technology's "Catalogue of the First Batch of Secondary Application Demonstration Guidance for Key New Materials", and won the first prize of China Industry-University-Research Cooperation Innovation Achievement Award and China Patent Excellence Award
.

"Winning the 'blue sky defense' is a long way to go, which requires in-depth research on the sources, emission characteristics and working conditions of air pollution, involving the coordinated control
of nitrogen oxides and volatile organic compounds (VOCs), PM2.
5, ozone and other pollutants.
" Shen Yuesong said that in the next step, he will lead the team to conduct in-depth research on the collaborative control of multiple pollutants, hoping to achieve "one-click processing"
.