Composite Catalyst Coating for Selective p-Xylene Synthesis
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Solution Overview
Problem
Existing catalysts are inefficient in producing p-xylene from carbon dioxide and hydrogen, with low productivity and selectivity, and existing catalysts for carbon monoxide and hydrogen do not effectively utilize oxygen defects for carbon dioxide adsorption.
Innovation Solution
A catalyst comprising a first ternary composite oxide of chromium, zinc, and zirconium, and a second catalyst of H-ZSM-5 zeolite coated with an amorphous silicon-containing oxide, where the first catalyst adsorbs carbon dioxide and hydrogen to produce methanol efficiently, and the second catalyst converts methanol to p-xylene while preventing isomerization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional catalysts (Cr2O3 and H-ZSM-5 with silicalite-1 coating) are used for producing p-xylene from carbon dioxide and hydrogen, then the catalyst structure is established, but the productivity and selectivity for p-xylene are low
Solution Approach 1:
The invention changes the coating material parameter from crystalline silicalite-1 to amorphous silicon-containing oxide, and modifies the zeolite structure from H-ZSM-5 to H-beta zeolite. These parameter changes result in improved p-xylene selectivity (达到90%以上) and productivity, resolving the contradiction between selectivity and productivity
Solution Approach 2:
The invention uses a composite catalyst system consisting of H-beta zeolite coated with amorphous silicon-containing oxide. The composite structure combines the shape-selective properties of H-beta zeolite with the surface properties of amorphous silicon oxide, achieving both high selectivity and high productivity for p-xylene production
2Productivity
If Cr2O3 catalyst is used for synthesizing methanol from carbon dioxide and hydrogen, then the methanol synthesis function is provided, but the oxygen defects are not effectively utilized for carbon dioxide adsorption
Solution Approach 1:
The invention changes the catalyst composition from pure Cr2O3 to a composite containing Cr-Zn-Al-Oxide. This compositional parameter change creates effective oxygen defects that enhance carbon dioxide adsorption efficiency while maintaining high methanol synthesis productivity
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 system efficiently produces p-xylene with high yield and selectivity by optimizing the reaction pathways and minimizing side reactions, utilizing the oxygen defects and spatial confinement effects of the composite oxide and zeolite structure.
Implementation Method 1
a second catalyst H-beta zeolite which is coated with amorphous silicon-containing oxide; the second catalyst converts methanol to p-xylene while preventing isomerization
Implementation Method 2
utilizing the oxygen defects and spatial confinement effects of the composite oxide and zeolite structure
Implementation Method 3
the first catalyst adsorbs carbon dioxide and hydrogen to produce methanol efficiently, utilizing the oxygen defects
Data Source
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Figure 3(a)
AI summary
Provided are: a catalyst for producing p-xylene, including: a first catalyst containing a ternary composite oxide of chromium, zinc, and zirconium, and a second catalyst containing H-ZSM-5 zeolite coated with an amorphous silicon-containing oxide; a method of producing the same; and a method of producing p-xylene using the same.