Method for preparing molecular sieve SCR catalyst, and catalyst prepared therethrough

Abstract

The invention discloses a method for preparing a molecular sieve SCR catalyst, and the catalyst prepared therethrough. Several molecular sieves are mixed, and then undergo ion exchange modification treatment by a transition metal or a rare earth metal, Fe is loaded through isopyknic impregnation, and Cu is loaded through one-stage or multistage liquid ion exchange. A technology for modifying the stable molecular sieve mixture with the transition and rare earth metals, a technology for loading Fe by the isopyknic impregnation process and a technology for loading Cu by the one-stage or multistage liquid ion exchange are combined, and a catalysis material obtained through stable and effective modification and loading control is applied to a carrier matrix after being blended to form a slurryin order to prepare the monolithic catalyst; results of fresh sample activity test and hydrothermal aging test show that the catalyst has a wide active temperature window and excellent hydrothermal aging resistance, and the N2O generation amount of the catalyst prepared in the invention is significantly lower than that of previous catalysts of the same type.

Description

technical field

[0001] The invention belongs to the technical field of catalyst preparation, in particular to the technical field of molecular sieve SCR (Selective Catalytic Reduction, Selective Catalytic Reduction) catalyst preparation, and particularly relates to the preparation of a high-efficiency molecular sieve SCR catalyst for purifying diesel vehicle exhaust and the prepared catalyst. Background technique

[0002] NOx is an important air pollutant and an important pollutant that forms photochemical smog and haze. With the rapid growth of the number of motor vehicles, NOx in motor vehicle exhaust has attracted widespread attention at home and abroad, and the technology for purifying NOx in motor vehicle exhaust has also been developed rapidly. As the share of diesel vehicles in automobiles continues to rise, diesel vehicle exhaust NOx purification technology has become a worldwide hot research topic. Ammonia selective catalytic reduction technology (NH 3 -SCR) is cu...

Examples

Embodiment 1

[0028] 1. Preparation of carrier molecular sieve raw materials.

[0029] Take Beta molecular sieve and SSZ-13 molecular sieve, the mass ratio of the two is 3:1, mix them evenly, add deionized water to make slurry, and then spray dry to obtain the molecular sieve carrier material.

[0030] 2. Modification of carrier molecular sieve materials

[0031] Configure 1000mL lanthanum nitrate solution, the solution La 3+ The concentration is 0.5mol / L, heated to 70°C, and 50g of carrier molecular sieve powder is added while maintaining strong stirring, and ion exchange is carried out in a constant temperature reaction kettle at 70°C, and the exchange time is 10h. The obtained slurry was filtered, washed three times with deionized water, and the obtained molecular sieve mud was dried at a drying temperature of 105°C in an air atmosphere for 24 hours. The dried molecular sieve mud was twisted and passed through a 40-mesh sieve. The obtained powder is recorded as La-Zeolite.

[0032] 3....

Embodiment 2

[0043] Mix Beta molecular sieve and SSZ-13 molecular sieve evenly, the mass ratio of the two is 3:1, after mixing evenly, carry out pulping, spray drying, and then use a concentration of 0.2mol / L yttrium nitrate solution for modification treatment, and then carry out For equal volume impregnation loading Fe and ion exchange loading Cu, other catalyst preparation parameters and conditions are the same as in Example 1 except for the difference in the type of salt used for molecular sieve modification. The obtained sample is designated as S2.

[0044] The amount of by-product N2O produced by comparing S1, S2 and B2 catalysts during the SCR reaction is as follows: figure 2 Shown, compare with B2, adopt the catalyst prepared by the present invention to produce N in catalytic reduction NOx process 2 The amount of O is reduced by nearly 50%, which obviously improves its N 2 selectivity, thus it can be seen that the N of the catalyst prepared by the catalyst preparation technology ...

technical field

[0001] The invention belongs to the technical field of catalyst preparation, in particular to the technical field of molecular sieve SCR (Selective Catalytic Reduction, Selective Catalytic Reduction) catalyst preparation, and particularly relates to the preparation of a high-efficiency molecular sieve SCR catalyst for purifying diesel vehicle exhaust and the prepared catalyst. Background technique

[0002] NOx is an important air pollutant and an important pollutant that forms photochemical smog and haze. With the rapid growth of the number of motor vehicles, NOx in motor vehicle exhaust has attracted widespread attention at home and abroad, and the technology for purifying NOx in motor vehicle exhaust has also been developed rapidly. As the share of diesel vehicles in automobiles continues to rise, diesel vehicle exhaust NOx purification technology has become a worldwide hot research topic. Ammonia selective catalytic reduction technology (NH 3 -SCR) is cu...

Examples

Embodiment 1

[0028] 1. Preparation of carrier molecular sieve raw materials.

[0029] Take Beta molecular sieve and SSZ-13 molecular sieve, the mass ratio of the two is 3:1, mix them evenly, add deionized water to make slurry, and then spray dry to obtain the molecular sieve carrier material.

[0030] 2. Modification of carrier molecular sieve materials

[0031] Configure 1000mL lanthanum nitrate solution, the solution La 3+ The concentration is 0.5mol / L, heated to 70°C, and 50g of carrier molecular sieve powder is added while maintaining strong stirring, and ion exchange is carried out in a constant temperature reaction kettle at 70°C, and the exchange time is 10h. The obtained slurry was filtered, washed three times with deionized water, and the obtained molecular sieve mud was dried at a drying temperature of 105°C in an air atmosphere for 24 hours. The dried molecular sieve mud was twisted and passed through a 40-mesh sieve. The obtained powder is recorded as La-Zeolite.

[0032] 3....

Embodiment 2

[0043] Mix Beta molecular sieve and SSZ-13 molecular sieve evenly, the mass ratio of the two is 3:1, after mixing evenly, carry out pulping, spray drying, and then use a concentration of 0.2mol / L yttrium nitrate solution for modification treatment, and then carry out For equal volume impregnation loading Fe and ion exchange loading Cu, other catalyst preparation parameters and conditions are the same as in Example 1 except for the difference in the type of salt used for molecular sieve modification. The obtained sample is designated as S2.

[0044] The amount of by-product N2O produced by comparing S1, S2 and B2 catalysts during the SCR reaction is as follows: figure 2 Shown, compare with B2, adopt the catalyst prepared by the present invention to produce N in catalytic reduction NOx process 2 The amount of O is reduced by nearly 50%, which obviously improves its N 2 selectivity, thus it can be seen that the N of the catalyst prepared by the catalyst preparation technology ...

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