阅读说明：本技术 用于低温选择性催化氧化氨的整体式催化剂、其制备方法和应用 (Monolithic catalyst for low-temperature selective catalytic oxidation of ammonia, preparation method and application thereof ) 是由 张登松 邓江 兰天伟 颜婷婷 于 2020-04-08 设计创作，主要内容包括：本发明公开了一种用于低温选择性催化氧化氨的整体式催化剂、其制备方法和应用,属于整体式热催化剂的制备工艺领域。该方法利用原电池反应,即置换反应来制备了整体式负载型催化剂。制备的整体式催化剂具有较高的低温氨氧化活性以及高N<Sub>2</Sub>选择性。该制备工艺快速,简单,成本低廉,可批量生产,可广泛应用于氨的选择性催化氧化领域。(The invention discloses an integral catalyst for low-temperature selective catalytic oxidation of ammonia, and a preparation method and application thereof, and belongs to the field of preparation processes of integral thermal catalysts. The method utilizes a galvanic reaction, namely a displacement reaction, to prepare the monolithic supported catalyst. The prepared monolithic catalyst has higher low-temperature ammoxidation activity and high N 2 And (4) selectivity. The preparation method is rapid, simple, low in cost, and suitable for mass productionAnd can be widely applied to the field of selective catalytic oxidation of ammonia.)

1. A monolithic catalyst for the low temperature selective catalytic oxidation of ammonia, characterized in that: the material composition is xM @ F, wherein M is an active metal element, x is the mass percent of the active metal element in the monolithic catalyst, and F is a metal fiber carrier; the mass percent x ranges from 0.1% to 10.0%, and the active metal element is loaded on the metal fiber carrier to form an active point position.

2. The monolithic catalyst for the low-temperature selective catalytic oxidation of ammonia according to claim 1, characterized in that: f is at least one carrier material of aluminum, copper, iron and nickel metal fibers.

3. The monolithic catalyst for the low-temperature selective catalytic oxidation of ammonia according to claim 1, characterized in that: m is at least one of platinum, copper, silver and iron, and M can perform galvanic reaction with the used metal fiber F.

4. The monolithic catalyst for the low-temperature selective catalytic oxidation of ammonia according to claim 1, characterized in that: the diameter of the metal fiber is 50-100 micrometers, and the length of the metal fiber is 1-10 millimeters.

5. A method of preparing a monolithic catalyst for the low-temperature selective catalytic oxidation of ammonia according to claim 1, characterized in that it comprises the following steps:

a. spreading metal fiber with diameter of 50-100 micron and length of 1-10 mm in deionized water for subsequent addition of metal salt solution;

b. slowly dripping a certain amount of metal salt solution onto the metal fiber prepared in the step a, and standing for at least 6 hours in a dark place after the metal salt solution is dripped, so as to finish the reaction;

c. c, standing in the step b, removing residual liquid after reaction, placing the reacted metal fiber in an oven with the temperature of not lower than 80 ℃, and drying for at least 6 hours;

d. and c, placing the metal fiber dried in the step c into a crucible, placing the crucible into a muffle furnace, raising the temperature to 300-500 ℃ at a heating rate of not less than 2 ℃/min, and preserving the temperature for at least 3 hours to obtain the monolithic catalyst for low-temperature selective catalytic oxidation of ammonia.

6. The process for the preparation of the novel monolithic catalyst for the selective catalytic oxidation of ammonia according to claim 5, characterized in that: in the step a, pretreating metal fibers with the diameter of 50-100 micrometers and the length of 1-10 millimeters by using a sodium hydroxide aqueous solution with the mass fraction of 0-5% for subsequent reaction with a metal salt solution; after at least 20 minutes of pretreatment, the liquid is removed and washed with deionized water for at least 3 more times; the metal fibers are spread in deionized water and await the subsequent addition of a metal salt solution.

7. The process for the preparation of the novel monolithic catalyst for the selective catalytic oxidation of ammonia according to claim 5, characterized in that: in the step b, the metal salt solution is an aqueous solution of a salt containing the active metal element M.

8. The process for the preparation of the novel monolithic catalyst for the selective catalytic oxidation of ammonia according to claim 5, characterized in that: in the step d, the mass percentage of active metal elements in the prepared monolithic catalyst for low-temperature selective catalytic oxidation of ammonia accounts for 0.1-10.0% of the total catalyst.

9. Use of a novel monolithic catalyst for selective catalytic oxidation of ammonia according to claim 1, characterized in that: as a monolithic catalyst for the low-temperature catalytic oxidation of ammonia.

Technical Field

The invention relates to a catalyst, a preparation method and application thereof, in particular to an integral catalyst for selective catalytic oxidation of ammonia, a preparation method and application thereof, which are applied to the technical fields of nitrogen oxide pollutant treatment and selective catalytic oxidation of ammonia. Especially applied to the preparation process of the monolithic thermal catalyst.

Background

Nitrogen oxides are the key objects of air pollution control in recent years. The method of ammonia selective catalytic reduction of nitrogen oxides to nitrogen and water is the mainstream nitrogen oxide removal method. In order to convert nitrogen oxides into nitrogen and water, excessive ammonia is generally required to be added to ensure that the content of nitrogen oxides in tail gas reaches the pollution discharge standard, but the escaped ammonia also causes atmospheric pollution. In addition, ammonium salt generated by the reaction of excessive ammonia and sulfur oxides in the flue gas can be continuously deposited in the tail gas purification unit, and the normal operation of the unit is hindered. Therefore, how to effectively solve the problem of ammonia escape is particularly important for eliminating atmospheric pollution and ensuring the normal operation of a tail gas purification system.

Currently, selective catalytic oxidation of ammonia is an effective technical means to solve the above problems. The key and difficult point of the technology is to prepare a high-performance catalyst, namely a catalyst with both low-temperature activity and nitrogen selectivity. The active component of the common powder type supported catalyst is metal elements such as copper, platinum, silver, iron and the like, and the carrier is various oxides including aluminum oxide, cerium oxide, titanium oxide and the like. The patent CN 105873678B develops a Cu-Ru alloy catalyst, but the preparation process is complex.

Disclosure of Invention

In order to solve the problems of the prior art, the invention aims to overcome the defects in the prior art, provide an integral catalyst for low-temperature selective catalytic oxidation of ammonia, a preparation method and application thereof, and particularly overcome the problems of high active component dosage, poor low-temperature activity and poor nitrogen selectivity of most of the existing powder catalysts. The invention utilizes a simple preparation method to prepare the monolithic catalyst with low load, high low-temperature activity and high nitrogen selectivity. The monolithic catalyst prepared by the method has the advantages of adjustable types and loads of active components and types and sizes of carriers, excellent catalytic ammonia oxidation activity and nitrogen selectivity, and wide application in the field of low-temperature selective catalytic ammonia oxidation.

In order to achieve the purpose of the invention, the invention adopts the following technical scheme:

an integral catalyst for low-temperature selective catalytic oxidation of ammonia comprises the material composition xM @ F, wherein M is an active metal element, x is the mass percent of the active metal element in the integral catalyst, and F is a metal fiber carrier; the mass percent x ranges from 0.1% to 10.0%, and the active metal element is loaded on the metal fiber carrier to form an active point position.

As a preferable technical scheme of the invention, F is at least one carrier material of aluminum, copper, iron and nickel metal fibers.

In a preferred embodiment of the present invention, M is at least one of platinum, copper, silver, and iron, and M is capable of reacting with the metal fiber F used in the galvanic cell.

As a preferred technical scheme of the invention, the diameter of the metal fiber is 50-100 microns, and the length of the metal fiber is 1-10 mm.

The invention relates to a preparation method of a monolithic catalyst for low-temperature selective catalytic oxidation of ammonia, which comprises the following steps:

a. spreading metal fiber with diameter of 50-100 micron and length of 1-10 mm in deionized water for subsequent addition of metal salt solution;

b. slowly dripping a certain amount of metal salt solution onto the metal fiber prepared in the step a, and standing for at least 6 hours in a dark place after the metal salt solution is dripped, so as to finish the reaction;

c. c, standing in the step b, removing residual liquid after reaction, placing the reacted metal fiber in an oven with the temperature of not lower than 80 ℃, and drying for at least 6 hours;

d. and c, placing the metal fiber dried in the step c into a crucible, placing the crucible into a muffle furnace, raising the temperature to 300-500 ℃ at a heating rate of not less than 2 ℃/min, and preserving the temperature for at least 3 hours to obtain the monolithic catalyst for low-temperature selective catalytic oxidation of ammonia.

In the step a, the metal fiber with the diameter of 50-100 microns and the length of 1-10 mm is pretreated by a sodium hydroxide aqueous solution with the mass fraction of 0-5% for subsequent reaction with a metal salt solution; after at least 20 minutes of pretreatment, the liquid is removed and washed with deionized water for at least 3 more times; the metal fibers are spread in deionized water and await the subsequent addition of a metal salt solution.

In a preferred embodiment of the present invention, in the step b, the metal salt solution is an aqueous solution containing a salt of the active metal element M.

In the step d, the mass percentage of active metal elements in the prepared monolithic catalyst for low-temperature selective catalytic oxidation of ammonia is 0.1-10.0%.

The application of the novel monolithic catalyst for selective catalytic oxidation of ammonia is used as a monolithic catalyst for low-temperature catalytic oxidation of ammonia.

Compared with the prior art, the invention has the following obvious and prominent substantive characteristics and remarkable advantages:

1. the monolithic catalyst for low-temperature selective catalytic oxidation of ammonia is prepared into a monolithic supported catalyst by utilizing a galvanic cell reaction, namely a displacement reaction, and the prepared monolithic catalyst has high low-temperature ammonia oxidation activity and high N₂Selectivity; has the advantages of low load capacity, high low-temperature activity and high nitrogen selectivity.

2. The preparation method is simple and rapid, has low cost, can be produced in batches, and can be widely applied to the field of selective catalytic oxidation of ammonia.

Drawings

FIG. 1 is a scanning electron micrograph of a Pt @ Al monolithic catalyst prepared according to example 1 of the present invention.

FIG. 2 is a chart of electron dispersion elemental analysis data for the Pt @ Al monolithic catalyst prepared in example 1 of the present invention.

Detailed Description

The above-described scheme is further illustrated below with reference to specific embodiments, which are detailed below: