Halogen-Doped Noble Metal Catalyst for Selective C-O Bond Cleavage
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Solution Overview
Problem
Current methods for selective hydrogenolysis of aromatic C—O bonds in compounds like lignin and its models face challenges such as high temperature and pressure requirements, ring saturation, and the need for harsh base additives, which affect selectivity and yield towards aromatic compounds like benzene and phenol.
Innovation Solution
A method involving a supported noble metal catalyst doped with halogen (chlorine or bromine) is used to cleave C—O bonds in compounds with an aromatic ring, operating under milder conditions and utilizing a hydrogen source, optionally with a zeolite, to enhance selectivity and yield towards aromatic compounds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If heterogeneous catalysts are used for hydrogenolysis of aromatic C—O bonds, then catalytic activity is improved, but high temperature and pressure are required leading to aromatic ring saturation
Solution Approach 1:
The patent modifies the catalyst composition by introducing halogen doping (Cl or Br) at specific concentrations (0.1-5 wt%) to change the electronic properties and selectivity of the noble metal catalyst, enabling the reaction to proceed at lower temperatures (80-150°C) and pressures (1-10 bar) while maintaining high catalytic activity and preventing aromatic ring saturation
Solution Approach 2:
The patent creates a composite catalyst system combining noble metal particles (Ru, Pd, Pt, Ni) with halogen dopants on a support material. This composite structure synergistically combines the high activity of noble metals with the selective properties of halogen-doped surfaces, achieving both high catalytic activity and high selectivity for C—O bond cleavage over ring hydrogenation
2Productivity
If base additives are used in the hydrogenolysis reaction, then catalytic efficiency is improved, but purification problems and alkaline waste handling are introduced
Solution Approach 1:
The patent removes the need for base additives entirely from the reaction system. By designing the catalyst to inherently provide the necessary basicity through its composition (noble metal halogen-doped structure), the patent eliminates the harmful byproducts and purification issues associated with external base additives like tBuONa, while maintaining high catalytic efficiency for C—O bond cleavage
3Quantity of substance
If high pressure hydrogenation is applied, then conversion of C—O bonds is improved, but aromatic ring saturation occurs
Solution Approach 1:
The patent changes the pressure parameter to moderate levels (1-10 bar) combined with optimized temperature (80-150°C) and catalyst composition (halogen-doped noble metal). This parameter optimization allows sufficient conversion of C—O bonds while preventing the thermodynamic drive toward aromatic ring saturation that occurs at higher pressures
Solution Approach 2:
The patent creates local electronic modification at the catalyst surface through halogen doping, which selectively enhances the catalytic sites for C—O bond cleavage while suppressing sites that would promote aromatic ring hydrogenation. This local quality change in catalyst surface electronics achieves high selectivity for aromatic product formation
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
This approach achieves higher selectivity and yield towards aromatic compounds while operating at lower temperatures and pressures, with the catalyst showing stability across multiple uses without significant loss in efficiency.
Implementation Method 1
Selective hydrogenolysis of the aromatic carbon-oxygen (C—O) bonds in aryl ethers is important for the generation of fuels and chemical feedstocks from biomass and for the liquefaction of coal
Implementation Method 2
This process is catalyzed by a soluble nickel carbene complex
Data Source
AI summary
A method for the selective cleavage of a compound comprising an aromatic ring and a C—O—C linkage in the presence of a heterogeneous catalyst is provided. The heterogenous catalyst may be a supported noble metal catalyst doped with a halogen selected from the group consisting of chlorine and bromine. By using this method, it is possible to increase the selectivity and/or yield (preferably both) of aromatic compounds.