Composite Catalyst for Ethylene Selectivity
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Solution Overview
Problem
Current methods for producing ethylene through Fischer-Tropsch synthesis have low selectivity for ethylene and high selectivity for methane and hydrocarbons with more than 3 carbon atoms, limiting their application and energy security due to reliance on petroleum-based feedstocks.
Innovation Solution
A catalyst comprising a metal oxide and modified MOR zeolite, where the zeolite is treated with fatty amines to occupy B acid sites, is used for the hydrogenation of carbon monoxide to produce light olefins, achieving high selectivity for ethylene and low selectivity for methane and hydrocarbons with more than 4 carbon atoms.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If traditional Fischer-Tropsch synthesis catalysts are used, then the conversion of carbon monoxide is achieved, but the selectivity for ethylene is low and methane and heavy hydrocarbons are produced in high amounts
Solution Approach 1:
The patent applies local quality by creating distinct functional zones within the catalyst system: the metal oxide component (Fe, Co, Ni, Cu, or Zn) provides specific catalytic activity for CO hydrogenation, while the MOR zeolite component with modified acid sites provides shape-selective control over product distribution. This spatial and functional differentiation within the composite catalyst enables high ethylene selectivity (75-82%) while suppressing methane and C4+ hydrocarbon formation.
Solution Approach 2:
The patent employs composite materials by combining metal oxide catalysts with MOR topology zeolite in a composite structure. The metal oxide phase (FeOx, CoOx, NiOx, CuOx, or ZnOx) serves as the active site for CO hydrogenation, while the MOR zeolite with fatty amine modification provides selective product formation and diffusion control. This composite architecture synergistically achieves high ethylene selectivity and suppressed byproduct formation that neither component can achieve alone.
2Productivity
If alkali metal oxide carriers are used to support iron-manganese catalyst, then high CO conversion rate is achieved, but light olefin selectivity remains limited
Solution Approach 1:
The patent applies parameter changes by systematically varying the metal oxide composition (Fe, Co, Ni, Cu, Zn), the MOR zeolite framework properties, and the fatty amine modification levels to optimize both CO conversion rate and ethylene selectivity. By adjusting these chemical and physical parameters of the composite catalyst, the system achieves high productivity (CO conversion) while maintaining high manufacturing precision (ethylene selectivity of 75-82%).
3Productivity
If vacuum impregnation method is used to prepare Fe/activated carbon catalyst, then high CO conversion rate is achieved, but ethylene selectivity is less than 30%
Solution Approach 1:
The patent introduces MOR topology zeolite as an intermediary component between the metal oxide catalyst and the reaction products. The zeolite acts as a mediator that selectively facilitates ethylene formation and diffusion while blocking the formation of methane and heavy hydrocarbons. This intermediary structure enables the system to maintain high CO conversion rates while achieving ethylene selectivity of 75-82%, overcoming the limitation of direct Fe/activated carbon catalysts.
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 selectivity of 75-82% for ethylene and less than 9% for methane, with hydrocarbon selectivity of C4 and above reduced to less than 10%, providing a more efficient and energy-independent ethylene production process.
Implementation Method 1
the zeolite is treated with fatty amines to occupy B acid sites
Implementation Method 2
the carbon monoxide and the hydrogen generate a Fischer-Tropsch synthesis reaction under the action of a proper catalyst
Implementation Method 3
the carbon monoxide and the hydrogen generate a Fischer-Tropsch synthesis reaction under the action of a proper catalyst to produce light olefin
Data Source
AI summary
An organic base modified composite catalyst for producing ethylene by hydrogenation of carbon monoxide is a composite catalyst and formed by compounding component I and component II in a mechanical mixing mode. The active ingredient of the component I is a metal oxide; the component II is an organic base modified zeolite of MOR topology; and a weight ratio of the active ingredients in the component I to the component II is 0.1-20, and preferably 0.3-8. The reaction process has an extremely high product yield and selectivity. The selectivity of C2-C3 olefins is as high as 78-87%; the selectivity of hydrocarbon products with more than 4 C atoms is less than 10%; the selectivity of a methane side product is extremely low (<9%); and meanwhile, the selectivity of the ethylene is 75-82%.