Issue 35/2014 - Analysis of patent applications for flue gas desulfurization catalysts

Analysis of patent applications for flue gas desulfurization catalysts

Beijing Center for Patent Examination Cooperation of the State Intellectual Property Office Li Yanfang Hao Peng,
Intellectual Property Department, Bureau of Science and Technology for Development, Chinese Academy of Sciences Cui Yong

As a global manufacturing center, China's annual fuel combustion exhaust gas emissions have exceeded 15 trillion cubic meters, which contains sulfur oxides that are the main substances
that form acid rain.
At present, flue gas desulfurization is the most effective technology for sulfur dioxide pollution control in China, and some analysts say that the annual market capacity in this direction has reached 50 billion yuan, and it is still showing a rapid growth trend
.
The heart of flue gas desulfurization technology is the catalyst
.
However, at present, the core catalysts of China's desulfurization technology almost all rely on imports, which is expensive
.
Therefore, it is of great significance to strengthen the research and development and application of
desulfurization catalysts with independent intellectual property rights.
The catalytic system for flue gas desulfurization will be discussed
below through domestic patent applications for active ingredients, carriers and absorbents.

1.
Active ingredients

1.
Metal oxides commonly used as active ingredients of catalysts include transition metal oxides and rare earth metal oxides

.

(1) Transition metal oxides vanadium or iron oxides
are commonly used active ingredients
.
Sinopec impregnates alumina and silica in a mixed solution containing vanadium, iron and silver ions, and roasts them at high temperatures to obtain catalysts
supported with vanadium, iron oxides and elemental silver.
Ocean University of China prepared a catalyst
with good desulfurization and denitrification performance and high mechanical strength using vanadium and/or iron oxides as active ingredients.

In addition to vanadium and iron oxides, other transition metal oxides can also be used as desulfurization catalysts
.
For example, China Petroleum and Chemical Corporation uses oxides of transition metals such as molybdenum, tungsten, nickel and cobalt as active ingredients, which has high desulfurization efficiency and high
selectivity in generating elemental sulfur.
Nanjing University of Science and Technology uses oxides of iron, cobalt, nickel, copper and other metals as active substances, which can be desulfurized and denitrified at the same time, and the by-product obtained is ammonium salt fertilizer
.

East China University of Science and Technology has developed microwave catalytic flue gas desulfurization technology, using manganese oxide, iron oxide, copper oxide, etc.
as catalysts, and fully contacting the flue gas with the catalyst under microwave heating, and the desulfurization effect is obvious
.
Shanghai University of Electric Power and Hunan Xiangda Environmental Engineering Co.
, Ltd.
use photocatalytic method with titanium dioxide as catalyst, and also achieve good desulfurization effect
.

(2) Rare earth metal oxides
are rich in rare earth resources in China, and have unique advantages
in the preparation of rare earth catalysts.
Dalian University of Technology uses kaolin as the carrier and lanthanum oxide and cerium oxide as the active ingredients; Hunan Xiangda Environmental Engineering Co.
, Ltd.
uses zeolite-supported NiO-CeO2 catalyst to achieve low-temperature liquid phase desulfurization and denitrification, and the catalyst is easy to recover and regenerate
.

2.
Metal salts China Power Investment Yuanda Environmental Engineering Co.
, Ltd.
and Chongqing University added ferrous salt and manganese salt as catalysts
in the limestone-gypsum method to promote the absorption rate
of sulfur in flue gas.
The Shanxi Institute of Coal Chemistry, Chinese Academy of Sciences mixes aqueous solutions containing iron, copper, cobalt, nickel vanadium and other salts with activated carbon fibers to make the supported metal salts in a nano state, which can give full play to the catalytic advantages of salts, and can still remove sulfur
with high activity at higher temperatures.

3.
Complex
complexes as the active ingredient of catalysts are mainly used in wet processes
.
East China University of Science and Technology has done a series of work in this regard, such as using ammonia and cobalt complexes as catalysts to improve the problem of water resistance of solid catalysts; The complex of ferrous salt is used as the absorbent, and the solution of calcium oxide, magnesium oxide or calcium carbonate is used as the desulfurization absorption solution, and the simultaneous desulfurization and denitrification
are realized.
The catalyst prepared by Soochow University et al.
contains iron coordination complexes; Qingdao University prepared a slurry with a solution containing aminocarboxylic acid ligands and pyrite powder, and the ferrous iron generated by leaching pyrite combined with the aminocarboxylic acid ligands to form ferrous complexing agents, both of which have good desulfurization effects
.

4.
Other
types of catalytic desulfurization systems
have been developed in recent years.
For example, China Textile Research Institute and China Petrochemical Corporation have developed catalytic desulfurization systems for precious metal oxides such as gold, silver and platinum; North China Electric Power University (Baoding) has disclosed a desulfurization catalytic oxidation system
with hydrogen peroxide as oxidant and glutaric acid as catalyst.

Second, the carrier (dry desulfurization)

For dry desulfurization, the performance of the carrier is related to the activity and life of the catalyst, which has an important impact
on the catalytic effect of the entire catalytic conversion system.

1.
Activated carbon/carbon fiber The Shanxi Institute of Coal Chemical Industry of the Chinese Academy of Sciences has successively used activated carbon, activated coke or semi-coke and carbon fiber as the carrier of the catalyst, and has done a lot of work
in dry desulfurization.
Taking patent CN03145680 as an example, V2O5 is loaded onto honeycomb activated carbon with straight-through macropore structure by activation-impregnation-calcination to obtain an efficient sulfur removal catalytic system
with mild reaction conditions.
Due to its large specific surface area, carbon fiber is easy to adsorb and desorption molecules
, and it also has obvious advantages for desulfurization.

2.
Silicone-containing complex oxides Beijing Institute of Technology uses zeolite molecular sieve 4A as the carrier and uses ferric chloride solution for ion exchange to obtain a flue gas desulfurization catalytic system
.
PetroChina uses Y-type zeolite and mercerized zeolite as the carrier, and introduces vanadium oxides or salts, and the obtained molecular sieve catalytic system has good selectivity
for SO2.

In addition to zeolite molecular sieve, diatomaceous earth (Ocean University of China), attapulgite and kaolin (Tsinghua University) can be used as carriers, which have good desulfurization effect
.

3.
Metal oxides Activated alumina, titanium dioxide, etc.
can also be used as carriers
.
For the former, China Petroleum and Chemical Corporation, Beijing Institute of Petrochemical Technology, and Kunming University of Science and Technology have done a lot of work; Peking University and the South China Institute of Environmental Sciences of the State Environmental Protection Administration have conducted some research
on the latter.

3.
Absorbent (wet desulfurization)

1.
Ammonia absorption method uses ammonia water as an absorbent to absorb sulfur in flue gas, and the product is oxidized to obtain ammonium sulfate fertilizer, and ammonia can be replaced by
ammonium compounds or urea.
East China University of Science and Technology disclosed the use of alkaline substances such as ammonia or ammonium as the absorption solution, and the catalyst is added to the absorption solution to synergize with ozone to desulfurize and denitrify at the same time; Yunnan Asia-Pacific Environmental Engineering Design and Research Co.
, Ltd.
disclosed a desulfurization system
with ammonia as the absorption liquid and manganese and iron ions as catalysts.

2.
Calcium-alkali method, also known as limestone-gypsum method, uses limestone, quicklime or slaked lime emulsion as absorbent, oxidation of the absorption solution can obtain by-product gypsum, absorbent is cheap and easy to obtain, high absorption efficiency, is currently one of
the most widely used methods for desulfurization.
China Petrochemical Corporation and others use limestone-gypsum method, and the conversion rate of sulfur in the exhaust gas can reach 98%.

Huadian Hi-Tech Environmental Protection Technology (Beijing) Co.
, Ltd.
uses this method to use ammonium acetate as a catalyst to economically improve the desulfurization efficiency
.

3.
Sodium-alkali method Sodium-alkali method is also widely used in flue gas desulfurization process, such as Beijing Lideheng Environmental Protection Engineering Co.
, Ltd.
, North China Electric Power University (Baoding), etc.
have disclosed the desulfurization process
with caustic soda, soda ash, etc.
as absorbents.

4.
Seawater desulfurization method Seawater desulfurization technology began in the 70s of the last century, and soon promoted and applied in Europe, America, Asia and other coastal power plants, natural seawater contains a large amount of soluble salt, usually alkaline, with natural acid-base buffering capacity and the ability to
absorb SO2.
In the "Several Opinions on Accelerating the Industrial Development of Flue Gas Desulfurization in Thermal Power Plants" issued by the National Development and Reform Commission in 2005, coastal power plants with a sulfur content of less than 1% can consider seawater desulfurization
.
Ocean University of China and others have disclosed the technology of using seawater desulfurization, using catalytic ceramics or modified structured polypropylene as fillers, and seawater is in reverse contact with the filler of the supported catalyst to remove sulfur
in flue gas.

IV.
Conclusion and Prospects

On the whole, the number of patent applications for flue gas desulfurization catalysts has shown a trend of increasing year by year, and certain progress has been made in the technology of active ingredients, carriers and absorbents.
The content of patented technology is constantly increasing; The application of catalysts has also attracted more and more attention
.
However, through the analysis of the technical level, it is not difficult to find some problems: first, China's strength in the research and development of flue gas desulfurization catalysts is relatively scattered, the technical level and research and development strength are uneven, some belong to the low level of repetitive work, and there are fewer core patents; Second, the awareness of patent protection needs to be strengthened, and a well-arranged patent pool
has not yet been formed.
To this end, the following suggestions are put forward:
First, in order to achieve low input and high output, it is necessary to adjust the existing industrial structure, refine the professional division of labor, integrate characteristic and advantageous industries, and carry out technical research in the direction of catalyst design, catalyst application, catalytic process improvement, and industrial amplification
.
The technical research and development of flue gas desulfurization catalysts not only depends on the strength of enterprises and scientific research, but also needs to rely on the support of national and government policies and investment
.
On this basis, we will further strengthen exchanges and cooperation to promote the transformation of scientific research results into real productivity
.

Secondly, in the face of the current good opportunity of China's implementation of intellectual property strategy, under the strong guidance of national environmental protection policies, it is urgent to cultivate a group of high-level and high-quality patent analysis talents in the research and development team of flue gas desulfurization catalysts, so that patent awareness is deeply rooted in the hearts of the people and escorts technological innovation
.
Encourage more basic patents and more core patents, strengthen the awareness of patent layout, strive to form a patent pool, and gradually occupy an absolute international dominant position
in the application field of flue gas desulfurization catalysts.