Pd-Ga-Au Silica Catalyst for Acetylene Selective Hydrogenation
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Solution Overview
Problem
Current catalysts for selective hydrogenation of acetylene to ethylene suffer from low selectivity and rapid hydrogenation of ethylene, leading to decreased ethylene quality and increased ethane production, which affects polyethylene production.
Innovation Solution
A catalyst comprising palladium, gallium, and gold supported on silica, prepared through a process involving mixing of metal sources, calcination, and reduction, forming a stable trimetal structure that enhances acetylene conversion and ethylene selectivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional catalysts are used for selective hydrogenation of acetylene to ethylene, then high conversion of acetylene is achieved, but selectivity of ethylene is low
Solution Approach 1:
The patent employs a trimetallic catalyst composite consisting of palladium, gallium, and gold supported on silica. This composite material combines the catalytic activity of palladium for acetylene hydrogenation with the selective properties of gallium and gold, which prevent over-hydrogenation to ethane. The synergistic interaction between the three metals achieves both high acetylene conversion and high ethylene selectivity simultaneously.
Solution Approach 2:
The catalyst design incorporates local quality differentiation through the specific arrangement and distribution of Pd, Ga, and Au atoms on the silica surface. The palladium sites provide the primary hydrogenation function while gallium and gold modify the local electronic and geometric properties to control product desorption, ensuring that ethylene is released before further hydrogenation can occur.
2Productivity
If conventional catalysts are used for hydrogenation reaction, then acetylene conversion is achieved, but ethylene product desorption is delayed causing excess hydrogenation to ethane
Solution Approach 1:
The patent extracts or removes the problematic property of strong product adsorption from the catalyst system by incorporating gallium and gold components that specifically weaken the interaction between the catalyst surface and ethylene product. This allows ethylene to be rapidly desorbed from the catalyst surface immediately after formation, preventing its re-adsorption and subsequent over-hydrogenation to ethane.
3Reliability
If precious metal content is increased to improve catalytic performance, then conversion and selectivity are enhanced, but production cost increases
Solution Approach 1:
The patent optimizes the parameters of precious metal content by using a trimetallic system where palladium provides the primary catalytic function at lower loadings, while gallium and gold enhance selectivity and stability. This parameter optimization allows the catalyst to achieve high performance with reduced overall precious metal content compared to conventional monometallic or bimetallic catalysts.
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 achieves high acetylene conversion (up to 99.4%) and ethylene selectivity (up to 99.2%) with prolonged stability and low production costs, maintaining performance for approximately 90 hours.
Implementation Method 1
the acetylene adsorption ability of the active sites can be increased and their ethylene adsorption ability can be decreased
Implementation Method 2
selective hydrogenation of acetylene to ethylene using the catalyst
Implementation Method 3
subjecting the catalyst precursor of step (a) to a calcination treatment
Implementation Method 4
subjecting a calcinated product of step (b) to a reduction reaction in a reducing atmosphere
Data Source
AI summary
A process for preparing a catalyst for selective hydrogenation of acetylene to ethylene, comprises: mixing palladium, gallium, and gold sources, silica, and a solvent to form a suspension, which is then subjected to filtration and drying so as to obtain a catalyst precursor; subjecting the catalyst precursor obtained to a calcination treatment; and subjecting a calcinated product obtained to a reduction reaction in a reducing atmosphere so as to obtain the catalyst. The catalyst prepared according to this process exhibits a high stability and high catalytic performance, and has a large number of active sites uniformly distributed.