Exhaust treatment for internal combustion engines

Abstract

The application provides an internal combustion engine exhaust treatment agent and relates to the technical field of exhaust treatment. The internal combustion engine exhaust treatment agent comprises cerium oxide 20-30 parts, zirconium oxide 30-35 parts, dilute sulfuric acid 35-50 parts and urea solution 15-30 parts. The cerium-zirconium composite oxide catalyst prepared by adopting sulfuric acid for sulfation is a new type of cerium-zirconium catalyst, which is beneficial to increase the chemical adsorption and activation of NH3 and increase the active oxygen component, significantly improve the NH3-SCR catalytic performance of CeO2, obviously improve the adsorption of CeO2 to NH3 after surface sulfation, thereby promote the Eley-Rideal reaction mechanism, and the adsorption sites and oxidation sites of the surface-NH2 of CeO2 after sulfation are separated, thereby the catalytic oxidation of-NH2 to NO can be effectively inhibited, the pollution to the environment is reduced, compared with vanadium, the pollution to the environment is lower, and compared with vanadium, the cerium reserves are large and the cost is lower. The economic benefit of the internal combustion engine exhaust treatment agent prepared by mixing the cobalt-cerium-zirconium composite oxide catalyst and the urea solution is effectively improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of tail gas treatment, in particular to a treatment agent for tail gas of an internal combustion engine. BACKGROUND

[0002] Compared with gasoline engines, diesel engines have higher thermal efficiency, better torque characteristics and lower CO2 emissions, but their NOx and PM emissions are much higher than those of gasoline engines. The reason is that diesel engines, unlike gasoline engines, use compression ignition combustion, which forms a combustible mixture by injecting diesel into high-temperature compressed air. The processes of atomization, evaporation, mixing and oxidation combustion occur simultaneously in the cylinder, so the diesel engine has lower fuel-air mixing uniformity than the gasoline engine, resulting in more NOx in some local areas. When the combustion temperature is low, less NOx is produced, but more PM is produced. To ensure sufficient combustion in the cylinder and reduce PM production, the combustion temperature needs to be as high as possible, which produces more NOx. After the implementation of the national IV standard, the control combustion technology used to reduce NOx emissions can no longer meet the requirements of more stringent standards, so a series of emission reduction technologies represented by SCR technology have been developed and applied. SCR technology was first applied to flue gas denitrification in thermal power plants, and in recent years it has been gradually applied to the treatment of exhaust gas from automobile and ship diesel engines. The main principle of SCR technology is to use NH3 as a reducing agent to react with NOx in the exhaust gas under the action of a catalyst to convert it into N2, thereby reducing NOx emissions. In the SCR technology for diesel engines, liquid ammonia is generally used as the source of NH3 because of its high risk, and urea solution is used to produce NH3 by decomposition, which is then reacted with NOx, so it is called "tail gas treatment liquid". In practical applications, the tail gas treatment liquid is stored in a vehicle-mounted storage tank and sprayed into the diesel engine exhaust gas at a temperature of 300-500℃. After the tail gas treatment liquid is gasified and decomposed, NH3 is produced and reacts with NOx in the exhaust gas in the SCR catalytic reactor to convert it into N2 and H2O. In the range of 230-500℃, the conversion efficiency of NOx can reach 40%-85%. The current commercial SCR catalyst is V2O5-WO3(MoO3) / TiO2, which has excellent catalytic performance in the medium and high temperature range.

[0003] The active component vanadium in the current tail gas treatment liquid is a highly toxic substance, which can cause secondary pollution to the environment if it falls off into the environment. In addition, the current tail gas treatment liquid also has the problems of high production cost and low economic benefit. SUMMARY

[0004] (I) Technical problems solved

[0005] In view of the deficiencies of the prior art, the present application provides a treatment agent for tail gas of an internal combustion engine, which solves the problems of the current tail gas treatment liquid, in which the active component vanadium is a highly toxic substance that can cause secondary pollution to the environment if it falls off into the environment, and the production cost of the catalyst is high.

[0006] (II) Technical Solution

[0007] To achieve the above object, the present application is implemented by the following technical solution: The internal combustion engine exhaust treatment agent comprises the following raw materials in parts by mass: cerium oxide 20-30 parts, zirconium oxide 30-35 parts, dilute sulfuric acid 35-50 parts, and urea solution 15-30 parts.

[0008] Preferably, the internal combustion engine exhaust treatment agent is composed of the following raw materials in parts by mass: cerium oxide 20 parts, zirconium oxide 30 parts, dilute sulfuric acid 35 parts, and urea solution 15 parts.

[0009] Preferably, the preparation method of the internal combustion engine exhaust treatment agent comprises the following steps:

[0010] S1, cerium oxide and zirconium oxide are added to dilute sulfuric acid in a certain proportion, and then constant temperature stirring is carried out in a stirrer, the stirring time is 2-5 hours, and a precursor solution is prepared;

[0011] S2, the precursor solution prepared in step S1 is placed in an evaporating dish for evaporation, and the precursor solution after evaporation and drying is left to stand for 2-3 hours to prepare a precursor;

[0012] S3, the precursor prepared in step S2 is calcined and tableted to prepare a cobalt-cerium-zirconium composite oxide catalyst;

[0013] S4, the cobalt-cerium-zirconium composite oxide catalyst prepared in step S3 is mixed with urea solution, and after mixing, stirring is carried out for 0.2-0.5 hours to prepare an internal combustion engine exhaust treatment agent.

[0014] Preferably, in step S1, the stirring temperature of the stirrer is controlled within 20-30 degrees.

[0015] Preferably, in step S2, the evaporation temperature of the evaporating dish is controlled within 70-80 degrees.

[0016] (III) Beneficial Effects

[0017] The present application provides an internal combustion engine exhaust treatment agent. It has the following beneficial effects:

[0018] The cerium-zirconium composite oxide catalyst prepared by adopting sulfuric acid for sulfation is a new type of cerium-zirconium catalyst, is beneficial to increase chemical adsorption and activation of NH3 and increase active oxygen components, significantly improves the NH3-SCR catalytic performance of CeO2, the adsorption of CeO2 to NH3 is obviously improved after surface sulfation, thereby promoting the Eley-Rideal reaction mechanism, and the adsorption site and oxidation site of CeO2 surface-NH2 are separated after sulfation, thereby effectively inhibiting the catalytic oxidation of-NH2 to NO, reducing the pollution to the environment, compared with vanadium, the pollution to the environment is lower, and compared with vanadium, the cerium reserves are large and the cost is lower. DETAILED DESCRIPTION

[0019] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0020] Embodiment one:

[0021] The internal combustion engine exhaust treatment agent provided in the embodiments of the present application is composed of the following raw materials in mass fraction: cerium oxide 20-30 parts, zirconium oxide 30-35 parts, dilute sulfuric acid 35-50 parts and urea solution 15-30 parts.

[0022] The internal combustion engine exhaust treatment agent is composed of the following raw materials in mass fraction: cerium oxide 20 parts, zirconium oxide 30 parts, dilute sulfuric acid 35 parts and urea solution 15 parts.

[0023] The preparation method of the internal combustion engine exhaust treatment agent comprises the following steps:

[0024] S1, cerium oxide and zirconium oxide are added to dilute sulfuric acid in a certain proportion, and then constant temperature stirring is carried out in a stirrer, the stirring time is 2-5 hours, and a precursor solution is prepared;

[0025] S2, the precursor solution prepared in step S1 is placed in an evaporating dish for evaporation, and the precursor after evaporation and drying is left to stand for 2-3h to prepare a precursor;

[0026] S3, the precursor prepared in the step S2 is calcined and tabletted to prepare a cobalt-cerium-zirconium composite oxide catalyst; and S4, the cobalt-cerium-zirconium composite oxide catalyst prepared in the step S3 is mixed with a urea solution, and after mixing, stirring is performed for 0.2-0.5 hours to prepare an internal combustion engine exhaust treatment agent.

[0027] S4, the cobalt-cerium-zirconium composite oxide catalyst prepared in the step S3 is mixed with a urea solution, and after mixing, stirring is performed for 0.2-0.5 hours to prepare an internal combustion engine exhaust treatment agent.

[0028] In the step S1, the stirring temperature of the stirrer is controlled within 20-30 degrees.

[0029] In the step S2, the evaporation temperature of the evaporating dish is controlled within 70-80 degrees, and constant temperature stirring can ensure that the sulfuric acid stably acidifies the cerium oxide and zirconium oxide, so that the prepared cobalt-cerium-zirconium composite oxide catalyst can effectively inhibit the catalytic oxidation of -NH2 to NO and reduce the pollution to the environment.

[0030] Example Two:

[0031] The internal combustion engine exhaust treatment agent provided by the embodiment of the present application comprises the following raw material components in mass fraction: cerium oxide 20-30 parts, zirconium oxide 30-35 parts, dilute sulfuric acid 35-50 parts, and urea solution 15-30 parts.

[0032] The internal combustion engine exhaust treatment agent comprises the following raw material components in mass fraction: cerium oxide 20 parts, zirconium oxide 30 parts, dilute sulfuric acid 30 parts, and urea solution 20 parts.

[0033] The preparation method of the internal combustion engine exhaust treatment agent comprises the following steps:

[0034] S1, cerium oxide and zirconium oxide are added to dilute sulfuric acid in a certain proportion, and then constant temperature stirring is performed in a stirrer, and the stirring time is 2-5 hours to prepare a precursor solution;

[0035] S2, the precursor solution prepared in the step S1 is put into an evaporating dish for evaporation, and the precursor prepared after the evaporated and dried precursor solution is left to stand for 2-3 hours;

[0036] S3, the precursor prepared in the step S2 is calcined and tabletted to prepare a cobalt-cerium-zirconium composite oxide catalyst. The cerium-zirconium composite oxide catalyst prepared by sulfation with sulfuric acid is a new type of cerium-zirconium catalyst, which has lower environmental pollution than vanadium, and the use of cerium has larger reserves and lower cost than vanadium. The sulfation of the cerium-zirconium composite oxide catalyst can also increase the content of surface Ce3 and strong acid sites, which is conducive to increasing the chemical adsorption and activation of NH3, increasing the active oxygen components, significantly improving the NH3-SCR catalytic performance of CeO2, and improving the adsorption of NH3 on the surface of CeO2 after sulfation. The Eley-Rideal reaction mechanism is promoted, and the adsorption sites and oxidation sites of -NH2 on the surface of CeO2 after sulfation are separated, which can effectively inhibit the catalytic oxidation of -NH2 to NO and reduce the pollution to the environment. The economic benefit of the internal combustion engine exhaust treatment agent prepared by mixing the cobalt-cerium-zirconium composite oxide catalyst with urea solution is effectively improved.

[0037] S4, the cobalt-cerium-zirconium composite oxide catalyst prepared in the step S3 is mixed with urea solution, and after mixing, stirring for 0.2-0.5 hours to prepare an internal combustion engine exhaust treatment agent.

[0038] In the step S1, the stirring temperature of the stirrer is controlled within 20-30 degrees, and constant temperature stirring can ensure that sulfuric acid is stably acidified on cerium oxide and zirconium oxide, so that the prepared cobalt-cerium-zirconium composite oxide catalyst can effectively inhibit the catalytic oxidation of -NH2 to NO and reduce the pollution to the environment.

[0039] In the step S2, the evaporation temperature of the evaporating dish is controlled within 70-80 degrees.

[0040] Although embodiments of the present application have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made therein without departing from the principles and spirit of the application, and the scope of the present application is defined by the appended claims and their equivalents.

Claims

1. A method for the preparation of an exhaust treatment agent for internal combustion engines, characterized in that: The internal combustion engine exhaust treatment agent is composed of the following raw materials in mass fraction: cerium oxide 20-30 parts, zirconium oxide 30-35 parts, dilute sulfuric acid 35-50 parts and urea solution 15-30 parts; S1, cerium oxide and zirconium oxide are added to dilute sulfuric acid in a certain proportion, then constant temperature stirring is carried out in a stirrer, and the stirring time is 2-5 hours to prepare a precursor solution; S2, the precursor solution prepared in step S1 is placed in an evaporating dish for evaporation, and the precursor solution after evaporation and drying is left to stand for 2-3 hours to prepare a precursor; S3, the precursor prepared in step S2 is calcined and tableted to prepare a cobalt-cerium-zirconium composite oxide catalyst; S4, the cobalt-cerium-zirconium composite oxide catalyst prepared in step S3 is mixed with urea solution, and after mixing, stirring is carried out for 0.2-0.5 hours to prepare an internal combustion engine exhaust treatment agent.

2. The method of claim 1, wherein: The internal combustion engine exhaust treatment agent is composed of the following raw materials in mass fraction: cerium oxide 20 parts, zirconium oxide 30 parts, dilute sulfuric acid 35 parts and urea solution 15 parts.

3. The method for preparing the internal combustion engine exhaust gas treatment agent according to claim 1, characterized in that: In the S1 step, the stirring temperature of the stirrer is controlled within 20-30 degrees.

4. The method for preparing the internal combustion engine exhaust gas treatment agent according to claim 1, characterized in that: In the S2 step, the evaporation temperature of the evaporating dish is controlled within 70-80 degrees.