Carboxylate-Ligated Pt Hydrosilylation Catalysts Against Aggregation
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Solution Overview
Problem
Existing hydrosilylation catalysts, particularly Pt-based catalysts, suffer from deactivation due to Pt aggregation and side reactions, high cost, and poor reusability, necessitating the development of more active and durable catalysts for efficient Pt utilization.
Innovation Solution
Development of ligand-coordinated supported catalysts (LCSCs) using bidentate N-based and carboxylic acid-based ligands to stabilize highly dispersed Pt cations on oxide supports, enhancing catalyst stability and reusability through metal-ligand complexation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If homogeneous Pt catalysts (Speier or Karstedt catalysts) are used for hydrosilylation, then high catalytic activity is achieved (TON > 1000000), but Pt aggregation occurs leading to deactivation and side reactions
Solution Approach 1:
The patent uses oxide supports (such as Al2O3, SiO2, TiO2, CeO2, or mixed oxides) as intermediary carriers to immobilize Pt species. The support acts as a mediator between Pt catalysts and reactants, preventing direct Pt aggregation while maintaining catalytic activity. The oxide support provides a stable platform that disperses Pt species and prevents their aggregation during the hydrosilylation reaction.
Solution Approach 2:
The patent employs porous oxide supports with controlled surface area and pore structure to disperse and stabilize Pt species. The porous structure provides high surface area for Pt anchoring, preventing aggregation while allowing reactant access. The specific surface area of the oxide support (5-500 m²/g) is optimized to balance Pt dispersion and catalytic activity.
2Reliability
If Pt complexes with updated ligand design (e.g., Pt-carbene complexes) are developed to achieve high activity and durability, then catalytic performance improves, but cost increases due to Pt scarcity
Solution Approach 1:
The patent changes the oxidation state parameter of Pt from typical Pt(0) or Pt(II) to Pt(IV) in the form of platinum oxide species on the oxide support. This parameter change enables higher stability and reusability while maintaining activity. The Pt(IV) oxidation state on oxide supports provides enhanced durability for multiple reaction cycles compared to traditional Pt complexes.
Solution Approach 2:
The patent creates composite catalyst systems combining Pt oxide species with oxide supports (Al2O3, SiO2, TiO2, CeO2, or mixed oxides). This composite structure leverages the synergistic effect between Pt and the oxide support, where the support provides stability and dispersion while Pt provides catalytic activity. The composite nature allows efficient Pt utilization with reduced loading (0.1-5 wt%).
3Ease of operation
If heterogeneous Pt catalysts are used to enable easy separation and recovery from soluble reactants/products, then catalyst recovery improves, but activity and reusability decrease due to Pt aggregation
Solution Approach 1:
The patent extracts the harmful aggregation tendency from Pt by immobilizing it on oxide supports. The Pt species are taken out of their aggregation-prone homogeneous state and anchored to the solid oxide support, enabling easy separation while preventing aggregation. This extraction of Pt from the solution phase to the solid support phase resolves the contradiction between separability and stability.
Solution Approach 2:
The patent performs preliminary anchoring of Pt species to the oxide support before the catalytic reaction. This preliminary action of immobilization prevents Pt aggregation during subsequent reaction cycles, ensuring long-term reusability. The Pt is pre-positioned on the support in a stable configuration that maintains activity while enabling easy separation.
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 new catalysts exhibit high activity, selectivity, and stability in hydrosilylation reactions, maintaining activity through multiple batches without noticeable deactivation, and offer improved Pt dispersion and tunable metal sites.
Implementation Method 1
Pt ligand-coordinated supported catalysts (LCSCs) have been developed through a novel metal-ligand coordination strategy
Implementation Method 2
a multi-carboxylic acid phenyl or biphenyl ligand to complex with a platinum metal ion and a support
Data Source
AI summary
The invention describes metal catalysts such as Pt single-site centers on metal oxide supports, e.g., powdered supports, such as MgO, Al2O3, CeO2 or mixtures thereof with phenyl or biphenyl ligands substituted with two or more carboxylic acid groups.