Dual-Catalyst Hydrocarbon Trap for Cold-Start Adsorption
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Solution Overview
Problem
Current zeolite-based hydrocarbon adsorption catalysts have insufficient high-temperature heat resistance and struggle to effectively adsorb short-chain hydrocarbons during the cold-start section of engine operation, leading to hydrocarbon slip and inadequate purification performance, especially under future exhaust regulation standards.
Innovation Solution
A dual-catalyst system comprising a first catalyst with zeolites of specific pore sizes (0.30 nm to 0.44 nm) for short-chain hydrocarbon adsorption and a second catalyst with ion-exchanged zeolites (0.45 nm to 0.90 nm) for long-chain hydrocarbon adsorption, both exhibiting improved heat resistance and adsorption efficiency through transition metal ion-exchange, delaying short-chain hydrocarbon diffusion until the three-way catalyst activation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If zeolite-based catalysts are used for hydrocarbon adsorption, then hydrocarbon adsorption capacity is improved, but high-temperature heat resistance deteriorates and structure collapses above 850°C
Solution Approach 1:
The patent changes the chemical composition parameters of the zeolite catalyst by incorporating specific metal elements (Pt, Pd, Rh, Ru, Ir, or Os) and adjusting the Si/Al ratio to ranges of 0.01-10 or 0.1-5. This compositional parameter optimization enhances the thermal stability and structural integrity of the zeolite framework at high temperatures while preserving its hydrocarbon adsorption capacity through controlled pore structures.
Solution Approach 2:
The patent creates a composite catalyst material by combining zeolite base structure with transition metal compounds. The composite structure integrates the high adsorption capacity of zeolite with the thermal stability and catalytic activity of metal components, achieving synergistic effects that simultaneously improve both adsorption performance and heat resistance.
2Quantity of substance
If conventional hydrocarbon trap is installed on underfloor, then hydrocarbon adsorption is achieved, but warm-up rate of three-way catalyst becomes slow causing hydrocarbon slip
Solution Approach 1:
The patent applies preliminary action by using the improved zeolite catalyst to pre-adsorb hydrocarbons during the cold-start phase before the three-way catalyst reaches operating temperature. The optimized zeolite structure with enhanced thermal stability allows it to maintain adsorption function during the warm-up period, preventing hydrocarbon slip and enabling smoother transition to three-way catalyst operation.
3Device complexity
If single catalyst type is used, then device complexity is reduced, but purification performance of both short-chain and long-chain hydrocarbons deteriorates
Solution Approach 1:
The patent achieves multi-functionality within a single catalyst formulation by incorporating metal compounds that can simultaneously handle both short-chain and long-chain hydrocarbons. The universal catalyst design uses specific metal elements (Pt, Pd, Rh, Ru, Ir, or Os) combined with optimized zeolite structures that provide broad-spectrum hydrocarbon adsorption and conversion capabilities, eliminating the need for separate catalyst types while maintaining high purification efficiency.
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 dual-catalyst system achieves enhanced hydrocarbon treatment efficiency, with the first catalyst showing ≥5% C3H6 treatment and the second catalyst showing ≥15% C7H8 treatment, effectively purifying hydrocarbons during the cold-start section and improving overall hydrocarbon discharge performance.
Implementation Method 1
a first catalyst configured to adsorb short-chain hydrocarbons and including zeolites having a pore size of about 0.30 nm to about 0.44 nm
Implementation Method 2
a second catalyst configured to adsorb a long-chain hydrocarbon and including zeolites ion-exchanged with transition metals
Implementation Method 3
zeolites ion-exchanged with transition metals
Data Source
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AI summary
A catalyst for adsorbing hydrocarbon includes a first catalyst configured to adsorb short-chain hydrocarbons and including zeolites having a pore size of about 0.30 nm to about 0.44 nm and a second catalyst configured to adsorb a long-chain hydrocarbon and including zeolites ion-exchanged with a transition metal. The catalyst can be coated on a substrate of a hydrocarbon trap.