Nitrogen-Phosphorus Modified Bimetallic Catalyst for Hydrodechlorination
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Solution Overview
Problem
Existing catalysts for hydrodechlorination reactions suffer from low catalytic activity, selectivity, stability, and short lifetime due to issues such as carbon deposition, sintering of metal particles, and poor interaction between active centers, limiting their industrial application, especially in the production of chlorotrifluoroethylene and 1,1,1,4,4,4-hexafluoro-2-butene.
Innovation Solution
A nitrogen-phosphorus-modified granular carbon-supported bimetallic catalyst with a high proportion of alloy phase particles, where nitrogen and phosphorus heteroatoms promote metal dispersion and interaction, forming a bifunctional active center that effectively dissociates hydrogen and activates C—Cl bonds, reducing excessive hydrogenation and carbon deposition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If precious metal active centers are used to dissociate hydrogen, then hydrogen dissociation activity is improved, but selectivity deteriorates due to excessive hydrogenation and stability deteriorates due to metal particle migration and sintering
Solution Approach 1:
The patent uses a bimetallic composite catalyst combining precious metal (Pd, Pt, or Ru) with copper or zinc on a nitrogen-phosphorus modified carbon carrier. The composite structure allows the precious metal to dissociate hydrogen while the copper/zinc component activates C-Cl bonds, preventing excessive hydrogenation and improving selectivity. The interaction between metal particles and the nitrogen-phosphorus modified carbon carrier prevents metal particle migration and sintering, enhancing catalyst stability.
2Reliability
If copper or zinc is added to activate C-Cl bonds, then selectivity is improved, but catalytic activity deteriorates due to insufficient hydrogen dissociation capability
Solution Approach 1:
The bimetallic composite catalyst combines copper or zinc with precious metal, where copper/zinc activates C-Cl bonds to improve selectivity, while the precious metal component maintains hydrogen dissociation activity. The synergistic effect of the two metals resolves the contradiction between selectivity and catalytic activity.
3Ease of manufacture
If traditional catalysts are used, then manufacturing simplicity is maintained, but productivity deteriorates due to low conversion rates and short catalyst lifetime
Solution Approach 1:
The patent modifies the carbon carrier by doping with nitrogen and phosphorus in specific ratios (N: 0.5-10 wt%, P: 0.1-5.0 wt%, N:P molar ratio: 1:1 to 1:5), which changes the surface properties and electronic structure of the carbon carrier. This enhancement improves metal particle dispersion and interaction, leading to higher conversion rates and extended catalyst lifetime while maintaining a feasible preparation process.
4Power
If metal particle size is reduced to increase dispersion, then catalytic activity is improved, but stability deteriorates due to increased sintering and migration
Solution Approach 1:
The nitrogen-phosphorus modified carbon carrier provides specific active sites and electronic properties that locally stabilize metal particles. The modification creates a heterogeneous surface with different regions having distinct functions: some regions promote metal particle dispersion for high activity, while other regions anchor metal particles to prevent sintering and migration, ensuring stability.
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 high raw material conversion rates and product selectivity, with a long lifetime and improved stability, making it suitable for the hydrodechlorination of chlorofluoro alkanes, particularly in the production of chlorotrifluoroethylene and 1,1,1,4,4,4-hexafluoro-2-butene.
Implementation Method 1
nitrogen and phosphorus heteroatoms promote metal dispersion and interaction, forming a bifunctional active center
Implementation Method 2
the dissociation of hydrogen molecules into adsorbed active hydrogen
Implementation Method 3
the active hydrogen attacks the C—Cl bond to generate HCl and complete the removal of chlorine
Data Source
AI summary
Provided are a nitrogen-phosphorus-modified granular carbon-supported bimetallic catalyst, a preparation method thereof and the use thereof. The catalyst comprises a nitrogen-phosphorus-modified carbon carrier and metal particles supported on the carbon carrier. The metal particles include first metal elementary substance particles, second metal elementary substance particles and bimetallic alloy phase particles. The percentage of the bimetallic alloy phase particles in the metal particles is ≥80%, and at least 90% of the alloy phase particles have a size of 1 nm to 20 nm. The catalyst has advantages such as a high proportion of alloy phase particles, a uniform particle size distribution, a high metal utilization rate, low costs, high stability and a high catalytic activity.