Platinum Catalyst on Acidic Alumina for Lean Burn Exhaust Purification
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Solution Overview
Problem
Conventional noble metal catalysts, such as those containing palladium (Pd) and rhodium (Rh), struggle to effectively purify hydrocarbons in the exhaust gas of lean burn engines, especially when oxygen concentrations are high, leading to deteriorated purification performance and potential failure to meet emission regulations.
Innovation Solution
A catalyst system is developed that includes an acidic support made of porous alumina with higher acidity than standard alumina, combined with platinum (Pt) as the active metal. This configuration reduces the binding force between platinum and oxygen, thereby enhancing the purification performance of saturated hydrocarbons even at increased oxygen concentrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional noble metal catalysts (Pd/Rh) are used, then the catalyst can function in lean burn engines, but the hydrocarbon purification rate deteriorates when oxygen concentration increases
Solution Approach 1:
The patent changes the oxygen binding energy parameter of the catalyst by selecting platinum group metals with specific binding energies. The catalyst uses Pt, Pd, or Ir metals that have optimized oxygen binding characteristics, allowing the catalyst to maintain hydrocarbon purification activity even when oxygen concentration increases in lean burn exhaust gas.
Solution Approach 2:
The patent employs a composite catalyst structure combining platinum group metals (Pt, Pd, Ir) with specific support materials. This composite approach creates synergistic effects where the metal components provide hydrocarbon oxidation activity while the support structure moderates oxygen binding, preventing oxygen poisoning and maintaining purification performance under varying oxygen concentrations.
2Productivity
If noble metals are used, then the catalyst can oxidize hydrocarbons, but oxygen adsorbs more strongly than hydrocarbon on the catalyst surface, poisoning reaction sites
Solution Approach 1:
The patent optimizes the oxygen binding energy parameter of the catalyst metal to a specific range that is weaker than conventional noble metals but still sufficient for hydrocarbon oxidation. This parameter change allows oxygen to adsorb less strongly, preventing site poisoning while maintaining the catalyst's ability to oxidize hydrocarbons effectively.
Solution Approach 2:
The support material acts as an intermediary between the platinum group metal and the exhaust gas components. It modifies the electronic properties of the metal, creating a controlled interaction environment where hydrocarbon oxidation can proceed efficiently while oxygen adsorption is moderated, preventing excessive oxygen binding that would poison reaction sites.
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 achieves excellent purification performance for saturated hydrocarbons, even under conditions of high oxygen concentration, thereby improving hydrocarbon removal efficiency and ensuring compliance with emission regulations.
Implementation Method 1
since the noble metals and oxygens (O) have larger adsorption energy than the hydrocarbon (HC) on the catalyst surface
Implementation Method 2
a catalyst for removing saturated hydrocarbons in exhaust gas of a lean burn engine
Data Source
AI summary
Disclosed is a catalyst for removing saturated hydrocarbon including an acidic support including porous alumina (Al2O3) and having higher acidity than alumina, and an active metal including platinum (Pt) and supported on the acidic support.