Yttrium-Modified Cu-SSZ-13 Catalyst for Diesel SCR
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Copper-based SCR catalysts for diesel engine exhaust purification face challenges such as low conversion rates at low temperatures, poor high-temperature performance, and susceptibility to hydrocarbon poisoning, with complex and costly production processes that complicate scale-up and increase wastewater generation.
Innovation Solution
A molecular sieve SCR catalyst is developed using a small-pore molecular sieve with a silicon-aluminum ratio ≤24, incorporating yttrium as a second active component, and a simplified slurry-coating method to enhance catalytic activity, hydrothermal stability, and hydrocarbon resistance, while reducing production costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If copper content is increased to improve low-temperature activity, then low-temperature performance is improved, but high-temperature performance and hydrothermal stability deteriorate
Solution Approach 1:
The patent uses a composite catalyst structure combining Cu-SSZ-13 molecular sieve with specific support materials and promoters. This composite approach allows optimization of both low-temperature activity (through Cu-SSZ-13) and high-temperature stability (through support materials and promoters) without relying on high copper content alone, thus resolving the contradiction between low-temperature performance and high-temperature stability
Solution Approach 2:
The patent modifies key parameters including copper content (optimized rather than maximized), molecular sieve structure (SSZ-13), support material composition, and promoter additives. By changing these parameters systematically, the catalyst achieves both low-temperature activity and high-temperature stability, resolving the trade-off between temperature performance at different ranges
2Productivity
If copper-based catalysts are used to improve catalytic activity, then NOx conversion is improved, but hydrocarbon poisoning resistance deteriorates
Solution Approach 1:
The patent creates a composite catalyst system where Cu-SSZ-13 provides NOx conversion activity while support materials and promoters modify the electronic and geometric properties of copper sites. This composite structure enhances resistance to hydrocarbon poisoning while maintaining high NOx conversion activity, resolving the contradiction between productivity and resistance to harmful factors
Solution Approach 2:
The patent introduces support materials and promoters as intermediary components that mediate between the copper active sites and the reaction environment. These intermediaries modify the catalyst properties to reduce hydrocarbon poisoning while preserving NOx conversion activity, thus resolving the contradiction between productivity and resistance to harmful factors
3Reliability
If complex production processes are used to improve catalyst performance, then catalytic performance is improved, but manufacturing complexity and cost increase
Solution Approach 1:
The patent incorporates active components and promoters during the molecular sieve synthesis process itself, rather than adding them separately in subsequent steps. This preliminary action simplifies the overall production process while maintaining high catalytic performance, as the active components are already in position during synthesis rather than requiring separate incorporation steps
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 catalyst exhibits excellent NOx conversion rates across a wide temperature range, high hydrothermal stability, and improved resistance to hydrocarbon poisoning, with a simplified and cost-effective production process.
Implementation Method 1
a molecular sieve SCR catalyst is developed using a small-pore molecular sieve with a silicon-aluminum ratio ≤24, incorporating yttrium as a second active component, and a simplified slurry-coating method to enhance catalytic activity
Implementation Method 2
The catalyst exhibits excellent NOx conversion rates across a wide temperature range
Implementation Method 3
incorporating yttrium as a second active component
Implementation Method 4
a simplified slurry-coating method to enhance catalytic activity, hydrothermal stability, and hydrocarbon resistance
Implementation Method 5
coating and calcinating: coating the slurry prepared in step (3) onto a catalyst support, drying and then calcining the same in air at 300-600° C. for 1-6 h
Data Source
AI summary
The invention discloses a molecular sieve SCR catalyst and a preparation method, the preparation method comprising the steps of: (1) heating deionized water to 60-90° C., and adding a soluble copper salt and an additive to stir and dissolve the same to prepare a copper solution; (2) heating the deionized water to 20-90°° C., adding a soluble yttrium salt to dissolve the same, and when maintaining the temperature, adding a molecular sieve with a silicon-aluminum ratio of ≤24 and stirring the same; when maintaining the temperature, adding a copper solution and stirring to perform ion exchange; (3) cooling the solution after the ion exchange in step (2), adding an adhesive, stirring and ball-milling the mixture, and standing to obtain a slurry; (4) coating the slurry onto a support, drying and then calcining to obtain a molecular sieve SCR catalyst. The catalyst prepared according to the present invention by using a small pore molecular sieve material with a lower silicon-aluminum ratio and adding yttrium as a second active component exhibits excellent catalytic activity for NOx at low and high temperatures, and has a wide active temperature window, high hydrothermal stability and good hydrocarbon resistance.