Pd-Containing Mixed Metal Oxide Coatings for Chlor-Electrolysis
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Solution Overview
Problem
Electrodes used in chlorine/chlorate production environments experience a higher operating potential and require a voltage 'break-in' period due to detrimental effects on chlorine evolution potential, leading to increased operational costs and inefficiencies.
Innovation Solution
An electrocatalytic coating comprising a transition metal oxide, such as palladium, ruthenium, or iridium, applied to a conductive substrate like titanium, which reduces the operating potential and eliminates the need for a voltage 'break-in' period by forming a passivating oxide film, thereby stabilizing the anode potential.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional metal oxide coatings are used on electrode substrates, then the electrode provides dimensional stability, but the chlorine evolution potential increases leading to higher operating potential and requiring a voltage break-in period
Solution Approach 1:
The patent applies composite materials by combining multiple metal oxides (ruthenium oxide, iridium oxide, titanium oxide, and optionally palladium oxide) in specific ratios to create a coating that achieves both dimensional stability and low operating potential. The composite nature of the coating allows synergistic effects where each oxide contributes different properties, resolving the contradiction between stability and energy efficiency.
Solution Approach 2:
The patent employs parameter changes by optimizing the specific composition ratios of metal oxides in the coating, the deposition conditions, and the heat treatment parameters. By carefully controlling these parameters, the coating achieves optimal catalytic activity for chlorine evolution while maintaining dimensional stability, thereby reducing operating potential without requiring a break-in period.
2Stability of the object's composition
If conventional metal oxide coatings are used, then the electrode achieves operational stability, but a voltage break-in period of several months is required to reach optimal performance
Solution Approach 1:
The patent applies preliminary action by performing specific heat treatment procedures during the manufacturing process to pre-condition the coating. This preliminary thermal treatment activates the catalytic properties and stabilizes the coating structure before the electrode is put into service, eliminating the need for a prolonged break-in period while maintaining operational stability.
Solution Approach 2:
The patent uses parameter changes by optimizing the heat treatment temperature, duration, and atmosphere to achieve immediate optimal performance. By controlling these parameters during manufacturing, the coating reaches its stable operational state beforehand, eliminating the time loss associated with conventional break-in periods.
3Stability of the object's composition
If post-baking of the coating is performed, then the coating structure is stabilized, but an escalation in voltage occurs after the baking process
Solution Approach 1:
The patent applies parameter changes by optimizing the post-baking temperature, time, and atmospheric conditions to stabilize the coating structure without causing voltage escalation. The specific parameter ranges are controlled to achieve complete stabilization of the oxide structure, preventing any subsequent voltage increase while maintaining structural integrity.
Solution Approach 2:
The composite material composition is designed to be inherently stable after baking, with the specific combination of metal oxides preventing structural changes that would lead to voltage escalation. The synergistic interaction between different oxides ensures long-term stability without the harmful effects seen in conventional single-oxide coatings.
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 coating significantly reduces the operating potential by 10-100 millivolts, eliminates the voltage 'break-in' period, and prevents postbake-induced anode potential escalation, enhancing the efficiency and stability of chlor-alkali electrolysis processes.
Implementation Method 1
an electrode having an electrocatalytic coating thereon which provides a reduction in the operating potential of the electrode in electrochemical cells for the oxidation of chloride to chlorine
Implementation Method 2
there rapidly forms a passivating oxide film which protects the underlying metal from corrosion by electrolyte
Implementation Method 3
the electrolytic production of chlorine and alkali metal hydroxides in membrane cells
Data Source
AI summary
The present invention relates to an electrocatalytic coating and an electrode having the coating thereon, wherein the coating is a mixed metal oxide coating, preferably platinum group metal oxides with or without valve metal oxides, and containing a transition metal component such as palladium, rhodium or cobalt. The electrocatalytic coating can be used especially as an anode component of an electrolysis cell for the electrolysis of a halogen-containing solution wherein the palladium component reduces the operating potential of the anode and eliminates the necessity of a “break-in” period to obtain the lowest anode potential.