CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority of Korean Patent Application No. 10-2019-0130124, filed on Oct. 18, 2019, in the KIPO (Korean Intellectual Property Office), the disclosure of which is incorporated herein entirely by reference.

BACKGROUND OF THE INVENTION

Field of the Invention

The present disclosure relates to a catalyst for directly decomposing urea and a method for decomposing urea using the same, more particularly to a catalyst for directly decomposing urea, which has improved ability of decomposing urea to ammonia by controlling the oxygen distribution of the catalyst and, thereby, inducing the decomposition of a byproduct such as biuret, and a method for decomposing urea using the same.

Description of the Related Art

Nitrogen oxide (NOx) is produced mainly from the combustion of fossil fuels and is generated from mobile sources such as ships or automobiles or stationary sources such as power plants or incinerators. The nitrogen oxide is regarded as one of the main causes that pollute the atmosphere through acid rain and smog. As the regulations on air pollution are becoming stricter recently, a lot of researches are being conducted on the reduction of nitrogen compounds such as nitrogen oxide using reductants.

As a method for removing nitrogen compounds exhausted from stationary sources, a nitrogen dioxide conversion catalyst, which uses ammonia, etc. as a reductant, titanium dioxide (titania, TiO2) as a support and vanadium oxide (V2O5) as an active catalytic component, is widely used. However, the use of ammonia as a reductant in the selective catalytic reduction reaction has a problem in that, since the ammonia is produced from hydrolysis under a high-temperature, high-pressure condition, it requires an excessively large reactor and excessive consumption of energy to maintain the temperature and pressure condition.

In addition, when urea is simply pyrolyzed, biuret is produced as a byproduct at temperatures of 200° C. or lower, which decreases the efficiency of ammonia production and lowers catalytic activity for selective catalytic reduction.

SUMMARY OF THE INVENTION

The present disclosure is directed to providing a new catalyst for decomposing urea, which is capable of improving the efficiency of decomposing urea to ammonia while preventing the formation of a byproduct such as biuret at temperatures of 200° C. or lower.

The present disclosure provides a catalyst for decomposing urea, the catalyst including: a titania support; and ceria supported on the titania, wherein the oxygen composition of the catalyst satisfies Equation 1.
0.8≤Oα+Oβ/Ototal≤0.87   [Equation 1]

In Equation 1, Oαrepresents lattice oxygen, Oβrepresents surface oxygen and Ototalrepresents total oxygen in the catalyst.

In an exemplary embodiment of the present disclosure, the catalyst for decomposing urea has a ceria content of 5.0-10.0 wt. % based on the total catalyst and the catalyst for decomposing urea is sintered at a temperature of 350-450° C. to satisfy the oxygen composition described above.

In an exemplary embodiment of the present disclosure, the catalyst for decomposing urea further includes antimony or zirconia.

In an exemplary embodiment of the present disclosure, the catalyst for decomposing urea further includes antimony, and the content of antimony is 1.5-2.5 wt. % based on the total catalyst.

In an exemplary embodiment of the present disclosure, the urea decomposition catalyst is sintered at a temperature of 550-650° C. to satisfy the oxygen composition described above.

In an exemplary embodiment of the present disclosure, the catalyst for decomposing urea further includes zirconia, and the content of zirconia is 1.5-2.5 wt. % based on the total catalyst.

In an exemplary embodiment of the present disclosure, the catalyst for decomposing urea is sintered at a temperature of 450-550° C. to satisfy the oxygen composition described above.

The present disclosure also provides a method for decomposing urea using the catalyst for decomposing urea described above, which includes: a step of injecting urea into a reactor equipped with the catalyst at a temperature of 180-200° C.; and a step of conducting a first reaction of decomposing urea to ammonia in the reactor.

In an exemplary embodiment of the present disclosure, a second reaction whereby biuret, which is a byproduct produced from the first reaction, is decomposed again is conducted by the catalyst for decomposing urea in the reactor, so that the efficiency of decomposing urea to ammonia is improved.

According to a catalyst for directly decomposing urea and a method for decomposing urea using the same of the present disclosure, the efficiency of decomposing urea to ammonia may be improved while preventing the formation of a byproduct such as biuret at temperatures of 200° C. or below by controlling the oxygen composition of the catalyst including titania and ceria.

