Cu/ZnO-Alumina-Silica Catalyst Composition for Deactivation Resistance
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Solution Overview
Problem
Existing copper-based catalysts for carbon oxide conversion reactions, such as the water-gas shift reaction and methanol synthesis, suffer from low initial activity and poor stability due to the use of silica-free or silica-containing catalysts derived from soluble aluminum salts, leading to reduced selectivity and longevity.
Innovation Solution
A catalyst composition comprising 30 to 70% copper oxide, zinc oxide, alumina, and silica, with a Si:Al atomic ratio of 0.005 to 0.15:1, prepared using an alumina sol, providing a high BET surface area and improved resistance to deactivation, is used for carbon oxide conversion reactions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If silica-free or silica-containing catalysts derived from soluble aluminum salts are used, then the catalyst can be manufactured with simpler processes, but the initial activity and stability are reduced
Solution Approach 1:
The patent changes the source material parameter from soluble aluminum salts to alumina sol, and adjusts the Si:Al atomic ratio to 0.005-0.15:1. This parameter change resolves the contradiction by providing both high initial activity (exceeding 37 m2/g copper surface area) and enhanced resistance to deactivation, while maintaining manufacturability through the sol-based preparation method.
Solution Approach 2:
The patent creates a composite catalyst system combining copper oxide, zinc oxide, alumina, and silica in specific proportions. This composite material approach resolves the contradiction by synergistically combining the benefits of silica (improved stability) and alumina sol (high surface area and activity), achieving both ease of manufacture and high reliability.
2Productivity
If the copper oxide content is increased to enhance initial activity, then the catalyst shows higher activity, but the resistance to deactivation may be reduced
Solution Approach 1:
The patent optimizes the copper oxide content within the range of 30-70% and combines it with specific amounts of zinc oxide, alumina, and silica. This balanced parameter configuration resolves the contradiction by ensuring sufficient copper oxide for high initial activity while maintaining adequate amounts of stabilizing components for resistance to deactivation.
Solution Approach 2:
The composite catalyst formulation with copper oxide (30-70%), zinc oxide, alumina, and silica creates a synergistic system where copper oxide provides high initial activity and the combination with zinc oxide, alumina, and silica provides enhanced stability and resistance to deactivation, resolving the contradiction between productivity and reliability.
3Productivity
If the BET surface area is increased to improve catalyst activity, then the initial activity increases, but the catalyst may become more susceptible to deactivation
Solution Approach 1:
The patent achieves a BET surface area of ≥105 m2/g through the use of alumina sol and optimized calcination conditions (300-450°C). This parameter optimization resolves the contradiction by creating a high surface area structure that maintains both high initial activity and enhanced resistance to deactivation through the stabilizing effect of the alumina sol-derived structure and silica addition.
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 exhibits high initial activity and enhanced resistance to deactivation, maintaining performance over time, with copper surface areas exceeding 37 m2/g and BET surface areas of ≥105 m2/g, suitable for methanol synthesis and water-gas shift reactions.
Implementation Method 1
wherein the alumina is derived from an alumina sol
Implementation Method 2
followed by calcination to convert the precipitated copper compounds, and other components as necessary, to the oxides
Implementation Method 3
the reduction effected by passing a suitable reducing gas mixture there-through
Data Source
AI summary
A catalyst suitable for use in carbon oxide conversion reactions is described, said catalyst in the form of a shaped unit formed from an oxidic catalyst powder, said catalyst comprising 30-70% by weight of copper oxide, combined with zinc oxide, alumina and silica, having a Si:Al atomic ratio in the range 0.005 to 0.15:1, and having a BET surface area ≥105 m2/g and a copper surface area >37 m2/g catalyst. The catalyst is prepared by a co-precipitation method using an alumina sol.