Electrocatalytic Muconic Acid Hydrogenation with Reusable Pd/Pt Cathodes
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Solution Overview
Problem
Current processes for hydrogenating muconic acid to form industrially relevant synthetic intermediates such as 3-hexene-1,6-dioic acid, 2-hexene-1,6-dioic acid, or adipic acid suffer from inefficiency, poor selectivity, and low yield.
Innovation Solution
An electrocatalytic method using a catalytic cathode with Pd or Pt on carbon, or a combination thereof, including a (111) facet, in an aqueous solution with a pH of 5.5 to 14, to hydrogenate muconic acid and yield products like adipic acid with selectivity ranging from 40% to 100%. This method also allows for the reuse of a rejuvenated catalytic cathode after removing catalyst poisons.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional hydrogenation processes are used to convert muconic acid to adipic acid or hexenedioic acid, then the reaction can proceed, but the processes suffer from inefficiency, poor selectivity, and low yield
Solution Approach 1:
The patent replaces conventional thermal hydrogenation methods with electrocatalytic hydrogenation. Instead of using thermal energy and metal catalysts in traditional hydrogenation processes, the invention employs electrical energy to drive proton reduction at a cathode, generating hydrogen in situ that reacts with muconic acid. This substitution of thermal/mechanical systems with an electrochemical system enables superior selectivity and yield while improving process efficiency.
Solution Approach 2:
The patent utilizes pH as a critical parameter to control the electrocatalytic hydrogenation process. By maintaining the aqueous solution at a pH of 5.5 to 14, the process optimizes proton availability for hydrogen generation while preventing unwanted side reactions. This parameter control enables the system to achieve high selectivity for desired products (adipic acid, 3-hexene-1,6-dioic acid, 2-hexene-1,6-dioic acid) while minimizing formation of unwanted byproducts, directly addressing the selectivity-yield contradiction.
2Productivity
If conventional hydrogenation processes are used, then conversion can occur, but they exhibit inefficiency and require higher catalyst loading
Solution Approach 1:
The invention replaces traditional metal catalysts with an electrocatalytic system where electrical energy directly drives the hydrogenation reaction. The cathode serves as both the source of hydrogen (via proton reduction) and the catalytic surface for muconic acid hydrogenation. This eliminates the need for separate catalyst components, significantly reducing catalyst loading requirements while improving conversion efficiency.
Solution Approach 2:
The electrocatalytic system generates hydrogen in situ at the cathode surface through proton reduction, eliminating the need for external hydrogen gas supply and traditional catalyst systems. The electrical energy input directly facilitates the hydrogenation reaction, making the system self-sufficient and reducing dependence on external catalysts, thereby improving efficiency while minimizing catalyst requirements.
3Productivity
If conventional hydrogenation is used, then products can be formed, but thermal degradation and explosion risks are present
Solution Approach 1:
The patent substitutes thermal hydrogenation with electrocatalytic hydrogenation, replacing heat-based reactions with electrical energy-driven proton reduction. This fundamental substitution eliminates thermal degradation risks while maintaining product formation capability. The reaction proceeds at ambient temperatures through electrochemical mechanisms, avoiding the thermal conditions that cause degradation in conventional processes.
Solution Approach 2:
The electrocatalytic hydrogenation process conducts hydrogen generation and consumption at the cathode surface in a controlled electrochemical environment. The in situ generation of hydrogen prevents accumulation of gaseous hydrogen in the reaction medium, eliminating explosion risks. The controlled release of hydrogen directly at the reaction interface creates a safe, inert-like environment that prevents harmful thermal and explosive side reactions.
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 achieves higher selectivity and conversion of muconic acid to desired products, reduces catalyst loading, minimizes thermal degradation, and avoids explosion risks by controlling hydrogen concentration, while being compatible with fermentation broths and producing only benign byproducts.
Implementation Method 1
passing current through a catalytic cathode in a reactor including an aqueous solution including the muconic acid... so as to hydrogenate the muconic acid
Implementation Method 2
hydrogenate the muconic acid to yield a product including 3-hexene-1,6-dioic acid, 2-hexene-1,6-dioic acid, adipic acid
Implementation Method 3
catalytic cathode including Pd on carbon, or Pt on carbon... wherein the Pd and Pt includes a surface (111) facet
Data Source
AI summary
An electrocatalytic method includes passing current through a catalytic cathode in a reactor including an aqueous solution including the muconic acid, a supporting electrolyte, and an anode, so as to hydrogenate the muconic acid to yield a product including 3-hexene-1,6-dioic acid, 2-hexene-1,6-dioic acid, adipic acid, or a mixture thereof. An electrocatalytic method includes passing current through a catalytic cathode in a reactor including an aqueous solution including an organic substrate, a supporting electrolyte, and an anode, so as to electrocatalytically convert the organic substrate, wherein the aqueous solution includes a fermentation broth including the organic substrate and including one or more catalyst poisons that reduce catalytic activity of the catalytic cathode; removing one or more catalyst poisons from the catalytic cathode to form a rejuvenated catalytic cathode; and reusing the rejuvenated catalytic cathode in the method.