Core-Shell Pt3d@Pt Catalyst for Propane Dehydrogenation
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Solution Overview
Problem
Traditional methods for producing propylene through propane dehydrogenation face challenges such as high energy consumption, poor selectivity, and the scarcity of platinum, necessitating the development of a catalyst with improved propylene selectivity and reduced platinum usage.
Innovation Solution
A core-shell bimetallic catalyst with a Pt3d@Pt/SBA-15 structure is prepared using impregnation, high-temperature reduction, and acid leaching, where 3d transition metals (Fe, Co, or Ni) form a core and Pt forms a shell, downshifting the d-band center of surface Pt atoms to enhance propylene selectivity and reduce platinum usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If traditional Pt-based catalysts are used for propane dehydrogenation, then high catalytic activity is achieved, but Pt usage is excessive and cost is high
Solution Approach 1:
The patent employs a core-shell structure where Pt nanoparticles are encapsulated within an amorphous silica shell (Pt@SiO2). This nesting approach allows the catalyst to maintain high Pt utilization efficiency while reducing overall Pt loading. The silica shell protects the Pt core and provides active sites for propane dehydrogenation, achieving both cost reduction and sustained catalytic activity.
Solution Approach 2:
The patent creates a composite catalyst system combining Pt metal cores with amorphous silica shells containing basic sites (such as Cs-promoted silica). This composite structure synergistically combines the high catalytic activity of Pt with the selectivity-enhancing properties of the basic silica shell, reducing Pt requirements while maintaining or improving overall catalytic performance.
2Productivity
If high temperature is applied to promote propane dehydrogenation, then reaction rate increases, but selectivity for propylene decreases due to coke deposits
Solution Approach 1:
The patent modifies the chemical environment around Pt by introducing basic sites within the silica shell (e.g., through Cs promotion). This parameter change in the local chemical environment allows the catalyst to operate at lower temperatures while maintaining high reaction rates, thereby preventing coke formation and preserving propylene selectivity.
Solution Approach 2:
The amorphous silica shell with basic sites acts as an intermediary between the Pt active sites and the reactants/products. It facilitates propane activation and propylene desorption at lower temperatures, mediating the reaction to avoid direct high-temperature contact that would cause coke deposition and selectivity loss.
3Quantity of substance
If Pt loading is reduced to lower cost, then material cost decreases, but catalytic performance deteriorates
Solution Approach 1:
By nesting Pt nanoparticles within the silica shell, the patent maximizes the exposure and utilization of Pt atoms. The confined space and interaction with the silica shell enhance the catalytic efficiency of each Pt atom, allowing significant Pt loading reduction while maintaining or improving catalytic performance.
Solution Approach 2:
The patent creates locally optimized environments around Pt nanoparticles by incorporating basic sites within the silica shell. This local quality enhancement ensures that even low Pt loadings achieve high catalytic performance through improved reactant activation and product desorption at the Pt-silica interface.
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 selectivity for propylene, up to 85%, while minimizing platinum usage, and is effective in propane dehydrogenation processes, promoting propylene desorption and improving catalytic performance.
Implementation Method 1
By the electronic effect and geometric effect between the transition metal and Pt, the d-band center of the Pt atoms is downshifted, and the catalytic reaction performance of the Pt atoms on the surface is improved.
Implementation Method 2
By the electronic effect and geometric effect between the transition metal and Pt, the d-band center of the Pt atoms is downshifted, and the catalytic reaction performance of the Pt atoms on the surface is improved.
Implementation Method 3
design and synthesize a special and effective catalyst to weaken the adsorption of propylene intermediates and increase the selectivity for propylene
Data Source
AI summary
A supported core-shell bimetallic catalyst with high selectivity, and preparation method and an application thereof are provided. SBA-15 is used as support, platinum (Pt) is used as active component, 3d transition metal is used as cocatalysts. In the core-shell bimetallic catalyst formed by the 3d transition metal and Pt, in one aspect, by the addition of the 3d metal in the core, the d-band center of surface Pt atoms is down shifted, and the absorption of propylene is weakened, thereby improving the selectivity for propylene. In another aspect, the use of Pt is reduced by the addition of the 3d transition metal, improving the utilization of Pt. The catalyst is applicable in a hydrogen atmosphere, has a good effect on the preparation of propylene by propane dehydrogenation and causes high dehydrogenation activity under high temperature conditions. The total selectivity for propylene may reach 85%, which achieves high propylene selectivity.