Catalyst End Face Hardening via Sequential Dipping
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Solution Overview
Problem
Catalysts used for denitration in exhaust gases from coal-fired boilers and incinerators suffer from abrasion due to high dust content, leading to a decrease in catalytic component density, especially when the density is below a certain threshold, resulting in inadequate abrasion resistance.
Innovation Solution
A method involving sequential dipping of a carrier structure's end face in an aqueous metal salt solution, followed by drying and a second dipping, then calcination, to enhance abrasion resistance, using concentrations of 2.7 to 3.88 mol/L for the metal salt solution, specifically with ammonium metatungstate or metavanadate solutions, to fill voids and harden the catalytic surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the density of catalytic component on catalytic surface is increased to improve abrasion resistance, then the catalyst becomes more resistant to dust abrasion, but the manufacturing complexity and cost increase
Solution Approach 1:
The patent applies preliminary action by performing end face hardening treatment before the catalyst is put into service. The carrier structure is dipped in aqueous metal salt solution, dried, dipped again, and calcined to form a hardened layer on the end face before dust abrasion occurs during operation. This preventive measure ensures abrasion resistance is established prior to actual use.
Solution Approach 2:
The patent applies local quality by performing hardening treatment specifically on the end face portion of the carrier structure where dust collision frequency is highest, rather than uniformly treating the entire catalyst surface. The aqueous metal salt solution is applied only to the end face, and the hardening is localized to this high-stress area, optimizing abrasion resistance where it is most needed while avoiding unnecessary treatment elsewhere.
2Strength
If aqueous metal salt solution is applied to fill voids between catalytic component particles, then the catalytic surface becomes harder and more abrasion-resistant, but the voids cannot be filled if the catalytic component density is low
Solution Approach 1:
The patent applies parameter changes by controlling the concentration of the aqueous metal salt solution within a specific range (2.7 to 3.88 mol/L in terms of mole of metal). This optimized concentration range ensures that the solution can effectively fill voids between catalytic component particles while maintaining appropriate catalytic activity. The specific concentration parameters are crucial for achieving both void filling and preserving catalytic functionality.
3Quantity of substance
If the catalyst is dipped in aqueous metal salt solution multiple times without drying, then the voids are filled with solution, but the abrasion strength cannot be improved because the voids are already saturated
Solution Approach 1:
The patent applies periodic action by implementing a cyclic process of dipping, drying, dipping, and calcining. The drying step between dipings is crucial as it removes excess solution and creates conditions for the second dipping to effectively penetrate remaining voids. This periodic repetition with intermediate drying allows progressive filling of voids and subsequent hardening through calcination, achieving improved abrasion strength.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The method effectively prevents abrasion of the catalyst even with high dust content exhaust gases, maintaining catalytic component density and extending the catalyst's lifespan, as demonstrated by minimal depth of abrasion in experimental catalysts compared to controls.
Implementation Method 1
dipping an end face portion of a carrier structure having a catalytic component carried thereon in an aqueous metal salt solution
Implementation Method 2
performing a calcination treatment to harden the catalytic end face
Implementation Method 3
drying the dipped end face portion
Data Source
AI summary
A method for producing a catalyst of the present invention is characterized by sequentially performing the steps of: (i) dipping an end face portion of a carrier structure having a catalytic component carried thereon in an aqueous metal salt solution at a concentration of 2.7 to 3.88 mol/L in terms of mole of the metal; (ii) drying the dipped end face portion; (iii) dipping the dried end face portion again in an aqueous metal salt solution whose metal species is the same as that in the aqueous metal salt solution at a concentration of 2.7 to 3.88 mol/L in terms of mole of the metal; and (iv) performing a calcination treatment to harden the catalytic end face.