Noble Metal-Promoted In2O3 Catalyst for CO2 Hydrogenation
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Solution Overview
Problem
Current catalysts for converting CO2 into methanol suffer from instability and reduced activity over time, particularly when exposed to impurities like SO2 and H2S, and there is a need for a more efficient process with higher selectivity and space-time yield.
Innovation Solution
A catalyst comprising indium oxide (In2O3) with a noble metal, such as palladium, prepared by co-precipitation at a pH above 8.5, which enhances stability and productivity by maintaining the noble metal in an oxidized form under reaction conditions, resulting in improved CO2 conversion to methanol with high selectivity and sustained activity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional Cu-based catalysts are used for CO2 hydrogenation to methanol, then initial activity is achieved, but significant loss of activity occurs within 100 hours due to water co-production
Solution Approach 1:
The patent changes the chemical composition parameters of the catalyst by using In2O3 as the base catalyst and adding noble metal promoters (Pd, Pt, Rh, Ru, Ir) in specific amounts (0.1-5 wt%). This compositional parameter change fundamentally alters the catalyst's interaction with reaction intermediates and products, preventing the deactivation mechanism that affects Cu-based catalysts while maintaining high activity for CO2 hydrogenation to methanol.
Solution Approach 2:
The patent creates a composite catalyst system by combining In2O3 with noble metal particles. The noble metals are deposited on the In2O3 surface, forming a composite structure where the In2O3 provides the base catalytic function and the noble metal particles enhance activity and stability. This composite approach allows the catalyst to maintain high productivity while achieving long-term stability exceeding 100 hours of continuous operation.
2Reliability
If indium oxide catalyst is used for methanol synthesis from CO2, then 100% selectivity towards methanol is achieved, but the catalyst requires specific preparation methods to maintain stability
Solution Approach 1:
The patent applies preliminary action by performing surface modification of In2O3 before the main catalytic function is activated. The noble metal particles are deposited on the In2O3 surface in advance, creating a pre-stabilized catalyst structure. This preliminary structuring prevents sintering and phase transformation of In2O3 during the initial activation and early operation stages, ensuring long-term stability without requiring complex post-synthesis treatments.
Solution Approach 2:
The noble metal particles act as intermediaries between the In2O3 surface and the reactant molecules. These metal particles facilitate the hydrogenation reaction by providing alternative reaction pathways with lower activation energies, while also protecting the In2O3 surface from direct interaction with harsh reaction conditions that would cause deactivation. The intermediary noble metals thus enhance both activity and stability.
3Productivity
If noble metal is added to enhance catalytic activity, then space-time yield increases six-fold, but catalyst complexity and cost increase
Solution Approach 1:
The patent applies local quality by concentrating the noble metal particles specifically on the In2O3 surface where the catalytic reaction occurs, rather than uniformly distributing them throughout the catalyst structure. The noble metals are deposited as surface particles with controlled size and distribution, creating local active sites with enhanced catalytic properties. This localized approach maximizes the productivity benefit while minimizing the amount of expensive noble metal required, thus reducing overall catalyst complexity and cost.
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 co-precipitated catalyst exhibits a six-fold increase in space-time yield and stability up to 500 hours, compared to impregnated analogues, with the noble metal phase maintaining its effectiveness without significant deactivation, ensuring high methanol production and selectivity.
Implementation Method 1
Noble metal-promoted IN2O3 catalyst for the hydrogenation of CO2 to methanol
Implementation Method 2
The catalyst is prepared by co-precipitation of a saline solution at a pH above 8.5 comprising an indium salt and a salt of the at least one additional metal selected from a noble metal
Data Source
AI summary
Method to prepare a catalyst for use in a process for the synthesis of methanol, comprising indium oxide in the form of In2O3, and at least one additional metal selected from a noble metal; and in that the average particle size of said noble metal phase is, preferably at least 0.05 nm, and less than 5 nm as determined by STEM-EDX, characterized in that the catalyst is prepared by co-precipitation of a saline solution at a pH above 8.5 comprising an indium salt and a salt of the at least one additional metal selected from a noble metal and optionally further comprising a salt of the at least one alkaline earth metal.