Cu/SiO2 Hydrogenation Catalyst Synthesis for Ethylene Glycol
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Solution Overview
Problem
Current methods for synthesizing Cu/SiO2 hydrogenation catalysts face issues such as poor stability, fast sintering, over-reduction, low catalytic activity, and difficulty in controlling pore size and particle size, leading to inefficient conversion and selectivity in the hydrogenation of Dimethyl Oxalate (DMO) or Diethyl Oxalate (DEO) to Ethylene Glycol (EG).
Innovation Solution
A method involving the mixing of a silica generating precursor with a copper precursor and adding an ammonium salt to achieve a pH between 5 to 9, followed by calcination, to form a hydrogenation catalyst with a particle size of 10 nm to 40 nm, which is then used in a reactor under controlled pressure and temperature conditions to enhance catalyst deposition and selectivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If Cu/SiO2 catalyst is used for hydrogenation of DMO/DEO, then selectivity toward Ethylene Glycol is improved, but catalyst stability deteriorates due to fast sintering of copper aggregates
Solution Approach 1:
The patent applies preliminary action by performing controlled reduction of CuO to Cu0 at 300-400°C in a hydrogen atmosphere before the main hydrogenation reaction. This pre-reduction step creates stable copper metal sites that maintain both high selectivity for ethylene glycol and catalyst stability during the hydrogenation process, preventing fast sintering of copper aggregates.
2Ease of manufacture
If ammonia evaporation method is used for catalyst synthesis, then copper deposition is achieved, but safety risks increase due to potential explosions and intoxications
Solution Approach 1:
The patent replaces the hazardous ammonia evaporation method with a safer alternative using copper nitrate and sodium hydroxide solution. This substitution eliminates the need for ammonia handling and evaporation, removing the associated explosion and intoxication risks while still achieving effective copper deposition on the silica support through a controlled precipitation reaction.
Solution Approach 2:
The patent introduces an intermediary substance (sodium hydroxide solution) to facilitate copper deposition without requiring ammonia. The NaOH solution acts as a mediator that reacts with copper nitrate to form copper hydroxide precipitate, which is then converted to copper oxide and finally reduced to copper metal, providing a safe pathway for copper deposition that eliminates hazardous ammonia handling.
3Productivity
If high liquid hourly space velocity is used for hydrogenation reaction, then productivity is improved, but catalytic activity decreases due to weak mechanical properties
Solution Approach 1:
The patent creates a composite catalyst structure where copper species are deposited on a silica support with specific surface area (300-600 m²/g). This composite structure provides both the mechanical strength needed to maintain catalytic activity at high LHSV and the high surface area required for efficient reaction. The strong interaction between copper and silica ensures structural integrity under high flow conditions while maintaining active 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 method provides a more stable, active, and selective catalyst with improved control over particle size and environmental safety, achieving higher conversion and selectivity of DMO or DEO to EG, and reducing the risks associated with ammonia evaporation methods.
Implementation Method 1
adding an ammonium salt to an end pH of between about 5 to about 9
Implementation Method 2
The method further comprises adding an ammonium salt to an end pH of between about 5 to about 9
Implementation Method 3
followed by calcination, to form a hydrogenation catalyst
Implementation Method 4
Methods for hydrogenating an oxalate comprise forming a reaction mixture by flowing a hydrogenation catalyst to a reactor, flowing a hydrogen source to the reactor, and flowing an oxalate to the reactor
Implementation Method 5
over-reduction of surface cuprous species into Cu0 during pretreatment and reaction
Data Source
AI summary
Embodiments described herein generally relate to hydrogenation catalysts, syntheses of hydrogenation catalysts, and apparatus and methods for hydrogenation. Methods for forming a hydrogenation catalyst may include mixing a silica generating precursor with a copper precursor and adding an ammonium salt to an end pH of between about 5 to about 9. Methods for hydrogenating an oxalate may include forming a reaction mixture by flowing a hydrogenation catalyst to a reactor, flowing a hydrogen source to the reactor, and flowing an oxalate to the reactor, wherein the hydrogenation catalyst has a particle size between about 10 nm to about 40 nm. Methods may further include reacting the oxalate to form ethylene glycol.