Direct Decomposition of Lower Hydrocarbons for Nanocarbon Production
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Solution Overview
Problem
The direct decomposition of lower hydrocarbons into functional nanocarbon and hydrogen in the presence of a catalyst faces challenges such as reduced conversion rates over time due to the accumulation of solid carbon materials on the catalyst, which inhibits active sites and requires costly purification of the hydrocarbon feedstock.
Innovation Solution
Introducing a low concentration of oxidizing or reducing gases, such as carbon dioxide, oxygen, or water, to selectively react with excess precursor carbon and amorphous carbon on the catalyst, preventing their accumulation and maintaining reaction efficiency, while also reducing the need for costly hydrocarbon purification.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the reaction temperature is raised to enhance percent one pass conversion, then the decomposition reaction rate increases, but a large amount of solid carbon materials are produced on the catalyst surface, causing conversion to decrease with time
Solution Approach 1:
The patent introduces a small amount of oxidizing gas (0.1-10 vol%) to convert the harmful amorphous carbon deposits into beneficial functional nanocarbon materials. The oxidizing gas selectively reacts with excess carbon precursors and amorphous carbon on the catalyst surface, transforming them from harmful substances that block active sites into desired functional nanocarbon products, thereby maintaining high conversion rates over extended periods
Solution Approach 2:
The patent changes the composition parameter of the reaction atmosphere by introducing oxidizing gas at controlled concentrations (0.1-10 vol%). This parameter change fundamentally alters the carbon deposition pathway, shifting from uncontrolled amorphous carbon formation to controlled functional nanocarbon synthesis, thereby resolving the contradiction between reaction rate and conversion stability
2Reliability
If high purity lower hydrocarbon is used to prevent catalyst inhibition, then conversion remains high, but costly purification apparatus is required
Solution Approach 1:
The patent converts the previously harmful effect of carbon-containing impurities and excess carbon deposits into a beneficial process by introducing controlled oxidizing gas. These carbon species are transformed into functional nanocarbon products, eliminating the need for expensive purification apparatus while maintaining high conversion rates
Solution Approach 2:
The system performs self-purification by using the oxidizing gas to continuously remove excess carbon precursors and amorphous carbon from the catalyst surface during the reaction process. This self-cleaning mechanism eliminates the need for separate purification apparatus, reducing device complexity while maintaining catalytic activity
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
This approach enhances the stability and efficiency of the catalyst by removing excess carbon species, prolonging catalyst life, and reducing production costs by minimizing the need for extensive hydrocarbon purification.
Implementation Method 1
selectively reacting excess precursor carbon of functional nanocarbon produced by direct decomposition reaction of a lower hydrocarbon and an amorphous carbon secondarily produced by the reaction with a low concentration of oxidizing gas
Implementation Method 2
selectively reacting excess precursor carbon of functional nanocarbon produced by direct decomposition reaction of a lower hydrocarbon and an amorphous carbon secondarily produced by the reaction with a low concentration of oxidizing gas, reducing gas or a mixture thereof
Implementation Method 3
direct decomposition of a lower hydrocarbon by using a catalyst
Implementation Method 4
direct decomposition reaction of a lower hydrocarbon into carbon and hydrogen is endothermic
Data Source
AI summary
In a reaction where a lower hydrocarbon is subjected to direct decomposition by using a catalyst to produce a functional nanocarbon and hydrogen, the lower hydrocarbon is subjected to the reaction in an coexistent gas comprising low concentration of oxidizing gas, reducing gas or a mixture thereof. The precursor of functional nanocarbon produced on the catalyst and amorphous carbon secondarily produced on the catalyst react with the coexistent gas so that being removed from the catalyst, making it possible to prevent the drop of conversion with time on stream due to the inhibition of the reaction by the precursor and by-product. In the case where the raw material of lower hydrocarbon is biogas, the coexistent gas can be easily contained in methane by lowering purification degree of methane.