Copper Catalyst for Oxychlorination Reducing Stickiness
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Solution Overview
Problem
Catalyst stickiness in oxychlorination processes for converting ethylene to dichloroethane is a significant issue, particularly at high copper loadings, which affects feedstock efficiencies and reactor performance, and existing catalysts with high alkali metal content are prone to deleterious stickiness and reduced efficiency.
Innovation Solution
A supported copper catalyst is prepared through a two-step impregnation process using an alumina support with copper, alkali metal, and alkaline earth metal salts, allowing for higher alkali metal content without increasing stickiness, and optimized to operate effectively in baffled-bed reactors with improved HCl conversion and reduced by-products.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high copper loading is used in the catalyst, then oxychlorination activity is improved, but catalyst stickiness increases
Solution Approach 1:
The patent changes the chemical composition parameters by incorporating specific alkaline earth metals (Ca, Sr, Ba) at optimized ratios with copper. This compositional parameter change allows high copper loading (improving activity) while the alkaline earth metals modify the catalyst surface properties to reduce stickiness, thus resolving the contradiction between productivity and harmful factors.
Solution Approach 2:
The patent creates a composite catalyst material combining copper with alkaline earth metals (Ca, Sr, Ba) on an alumina support. This composite structure leverages the high activity of copper while the alkaline earth metal components provide anti-stickiness properties, allowing the system to achieve both high productivity and reduced harmful effects simultaneously.
2Productivity
If high alkali metal content is used in the catalyst, then catalytic activity is improved, but catalyst stickiness increases
Solution Approach 1:
The patent modifies the chemical composition by replacing or supplementing alkali metals with alkaline earth metals (Ca, Sr, Ba). This parameter change in metal type and ratio maintains or enhances catalytic activity while fundamentally reducing the stickiness problem associated with high alkali metal content, as alkaline earth metals have different surface interaction properties.
Solution Approach 2:
The alkaline earth metals act as intermediary components that mediate between the copper active sites and the alumina support. They provide a compositional buffer that maintains catalytic activity while reducing direct interactions that cause stickiness, effectively decoupling the activity-stickiness relationship.
3Productivity
If high temperature operation is used, then reaction rate is improved, but carbon oxide by-products increase
Solution Approach 1:
The patent changes the operational parameters by optimizing the temperature range and combining it with specific catalyst composition (copper with alkaline earth metals). This compositional-parameter combination allows the system to operate at higher temperatures for improved reaction rate while the catalyst composition selectively promotes the desired oxychlorination reaction over combustion reactions that produce carbon oxides.
Solution Approach 2:
The patent creates local active sites with specific copper-alkaline earth metal ratios that provide selective catalysis. These localized compositional variations ensure that even at high temperatures, the reaction proceeds through the desired pathway (ethylene + HCl + 0.5O2 → EDC) rather than complete combustion, thus maintaining high reaction rates while suppressing carbon oxide 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
The catalyst composition significantly reduces catalyst stickiness, enhances HCl conversion, lowers chlorinated and oxidation by-products, and allows for stable operation at high temperatures without carbon oxide production, improving overall reactor efficiency and product yield.
Implementation Method 1
impregnating, within a first step, an alumina support with a first aqueous solution including copper and a transition metal to thereby form a first catalyst component; and impregnating, within a subsequent step, the first catalyst component with a second aqueous solution including copper and alkaline earth metal
Implementation Method 2
converting ethylene to 1,2-dichloroethane in the presence of a supported copper catalyst, oxygen, and hydrogen chloride
Data Source
AI summary
In an oxychlorination process of the type where ethylene is converted to 1,2-dichloroethane in the presence of a supported copper catalyst, the improvement comprising: the use of a supported catalyst prepared by (i) impregnating, within a first step, an alumina support with a first aqueous solution including copper, to thereby form a first catalyst component; and (ii) impregnating, within a subsequent step, the first catalyst component with a second aqueous solution including copper and alkaline earth metal, to thereby form the supported catalyst.