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CN-119175069-B - Integral adsorbent based on 3D printing technology, preparation method and low-temperature cold start application thereof

CN119175069BCN 119175069 BCN119175069 BCN 119175069BCN-119175069-B

Abstract

The invention provides an integral adsorbent based on a 3D printing technology. According to the invention, the halloysite nanotube and the hydroxypropyl methylcellulose are selected as the binder, the halloysite nanotube has excellent high temperature resistance, hardness, durability and chemical stability, can meet the application requirements of a catalyst under high-temperature complex working conditions, ensures that the catalyst structure maintains mechanical stability, and the hydroxypropyl methylcellulose has treatability and plasticity, can help print out complex shapes and structures, has super-strong adhesive force and interlayer adhesion, can effectively adhere printing materials, ensures the firmness and stability of interlayer adhesion in the printing process, and is beneficial to reducing distortion and deformation in the printing process. The integral passive NO x adsorbent provided by the invention is simple and feasible in preparation method, is a non-noble metal adsorbent with economic benefit, and is connected with a downstream SCR (selective catalytic reduction) treatment unit in series to realize ultralow emission of NOx in a cold start stage.

Inventors

  • LI DAN

Assignees

  • 吉林大学

Dates

Publication Date
20260508
Application Date
20240718

Claims (7)

  1. 1. The coaxial 3D printing tandem catalyst is characterized by comprising a core and a shell which are coaxially arranged, wherein the core is made of an integral adsorbent, and the shell is a nitrogen oxide selective catalytic reduction unit; the integral adsorbent is prepared from the following raw materials in parts by mass through 3D printing: 8-18 parts by mass of Mn/Al 2 O 3 powder; 1-6 parts by mass of halloysite nanotubes; 0.1-1 parts by mass of hydroxypropyl methylcellulose; 80-90 parts by mass of solvent ethanol.
  2. 2. The coaxial 3D printing tandem catalyst according to claim 1, wherein the Mn/Al 2 O 3 powder has a manganese loading of 0.1-20 wt.%; the preparation method of the Mn/Al 2 O 3 powder comprises one of an excessive dipping method, an isovolumetric dipping method and a solid grinding method; the preparation method of the Mn/Al 2 O 3 powder comprises the following steps: mixing Al 2 O 3 with manganese salt in a solvent for reaction, removing the solvent, drying and calcining to obtain Mn/Al 2 O 3 powder; The manganese salt is selected from one of manganese nitrate, manganese acetate, manganese sulfate and manganese chloride.
  3. 3. The coaxial 3D printing tandem catalyst according to claim 1, further comprising rare earth modification of Al 2 O 3 prior to mixing Al 2 O 3 with manganese salt in solvent, wherein the rare earth element is one or more of La, pr, nd, Y, ce, zr, sm, pm, eu, gd, and wherein the rare earth element loading is 0.2 wt to 5.0 wt%.
  4. 4. The coaxial 3D printed tandem catalyst of claim 1, wherein the method of preparing the monolithic adsorbent comprises the steps of: a) Mixing Mn/Al 2 O 3 powder, halloysite nanotubes and a solvent, and heating to obtain a pasty mixture; mixing and stirring the pasty mixture and hydroxypropyl methylcellulose to obtain a 3D printing material; B) Placing the 3D printing material in a 3D printer, establishing a path by computer programming, and stacking the extruded Mn/Al 2 O 3 fibers through a 3D printing system to form a required shape to obtain an integral adsorbent precursor; c) Drying and calcining the integral adsorbent precursor to obtain an integral adsorbent; or comprises the following steps: a) Mixing Al 2 O 3 , manganese salt and halloysite nanotubes in a solvent, and heating to obtain a pasty mixture; mixing and stirring the pasty mixture and hydroxypropyl methylcellulose to obtain a 3D printing material; b) Placing the 3D printing material in a 3D printer, establishing a path by computer programming, and stacking the extruded Mn/Al 2 O 3 fibers through a 3D printing system to form a required shape to obtain an integral adsorbent precursor; c) And drying and calcining the monolithic adsorbent precursor to obtain the monolithic adsorbent.
  5. 5. The coaxial 3D printing tandem catalyst according to claim 4, wherein the heating temperature is 60-100 ℃, the calcining temperature is 500-650 ℃ and the time is 4-8 hours.
  6. 6. The coaxial 3D printing tandem catalyst according to claim 1, wherein the primary material of the shell is selected from one or more of Cu-SSZ-13、Cu-SSZ-39、Cu-SAPO-18、Cu-SAPO-34、Fe-SSZ-13、Fe-SSZ-39、V 2 O 5 -WO 3 /TiO 2 、V 2 O 5 -MoO 3 /TiO 2 ; the mass ratio of the core to the shell is 4:1-1:4; The preparation method of the coaxial 3D printing tandem catalyst comprises the following steps: 1) Respectively configuring a core and a shell layer into a 3D printing material; Mixing Mn/Al 2 O 3 powder, halloysite nanotubes and a solvent, heating to obtain a pasty mixture, and mixing and stirring the pasty mixture and hydroxypropyl methylcellulose to obtain a core 3D printing material; Mixing and stirring a shell main material, halloysite nanotubes and a solvent to obtain a pasty mixture, and mixing and stirring the pasty mixture and hydroxypropyl methylcellulose to obtain a shell 3D printing material; 2) Extruding the core 3D printing material and the shell 3D printing material through a coaxial needle head of a 3D printing system, and stacking the materials into a required shape to obtain a coaxial catalyst precursor; 3) And drying and calcining the coaxial catalyst precursor to obtain the coaxial catalyst.
  7. 7. An application of the coaxial 3D printing tandem catalyst according to any one of claims 1-6 in realizing ultra-low emission of NO x in cold start stage.

Description

Integral adsorbent based on 3D printing technology, preparation method and low-temperature cold start application thereof Technical Field The invention belongs to the technical field of adsorbents, and particularly relates to an integral adsorbent based on a 3D printing technology, a preparation method and low-temperature cold start application thereof. Background NO x emissions during the cold start phase of diesel vehicles have been an important environmental challenge. During the cold start phase, the temperatures of the engine and the exhaust purification system are low, the combustion process is incomplete and the catalytic reaction is inefficient, resulting in increased NO x emissions. Therefore, reducing the NO x emissions during the cold start phase of diesel vehicles has significant environmental implications and engineering challenges. The study of NO x emissions during the cold start phase of diesel vehicles involves a number of considerations. First, it is necessary to understand the operating principles of diesel engines and exhaust purification systems under cold start conditions, as well as factors affecting their performance. Second, there is a need to explore means of improving the engine combustion process and exhaust gas purification system to increase the NO x conversion efficiency during cold start. In addition, the influence of factors such as fuel ratio, catalyst activity, temperature control system and the like on the NO x emission needs to be considered, and an effective control strategy is sought. In recent years, with the increase of environmental protection requirements and the development of technology, research on reduction of NO x emissions in the cold start stage of diesel vehicles is attracting more and more attention. Certain advances have been made by improving engine control strategies, optimizing exhaust gas purification system designs, introducing new catalyst materials, and the like. However, there is still a need for further research and technical innovation to achieve a more effective reduction of NO x emissions during the cold start phase of diesel vehicles, thereby protecting the environment and improving the air quality. To reduce NO x emissions during cold start, passive NO x adsorption (PNA) has been developed. PNA is capable of adsorbing NO x during cold start up and releasing it to a downstream nitrogen oxide selective catalytic reduction unit (SCR) for catalytic conversion after temperature rise. Noble metal palladium-supported molecular sieves are currently the most widely studied PNA materials, which have excellent adsorption capacity and resistance to chemical poisoning. However, the high cost of noble metal catalysts is an important factor limiting their wide application. First, the rarity and precious nature of the precious metal itself results in its high price. The market price of noble metals such as palladium, gold, platinum, rhodium and the like is high, which directly affects the preparation cost of the noble metal adsorbent. Second, the preparation of high performance noble metal adsorbents requires complex processes and precise control, which also increases their cost. From the selection of raw materials, the synthesis of the adsorbent to the subsequent treatment and characterization, each step requires a significant amount of resources and time. In addition, recovery and reuse of noble metal catalysts also face technical challenges and cost pressures. Since noble metal adsorbents are commonly used under high temperature and pressure conditions, their surface activity is susceptible to contamination or deactivation, requiring periodic replacement or regeneration, which requires additional cost expenditures. Accordingly, researchers have been striving to find ways to reduce the cost of adsorbents, including developing new synthetic strategies, designing highly efficient support materials, and improving the stability and recycling rate of adsorbents in an effort to achieve a wider range of PNA adsorbents for industrial use. Based on this, some researchers turn their eyes toward non-noble metal loaded materials. For example, non-noble metal loaded molecular sieve adsorbents, mn, co, ni, ce oxides, and the like. Wherein the Mn/Al 2O3 powder material is a non-noble metal loaded material with excellent performance. 3D printing technology is an advanced manufacturing technology that converts digital models into physical objects, also known as additive manufacturing. The 3D printing technique has many advantages over conventional subtractive manufacturing. For example, (1) 3D printing techniques can customize the manufactured product as needed to meet personalization requirements. This is very useful in the medical, consumer, automotive, etc. fields. (2) While conventional manufacturing methods may take weeks or even months to prototype, 3D printing techniques may prototype in hours or less, thereby speeding up the product development cycle. (3) Conventi