Microporous Carbon Materials for Nitrogen Separation
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Solution Overview
Problem
Current microporous carbon materials are inadequate for efficiently separating nitrogen and other gases like hydrogen sulfide, carbon dioxide, and hydrocarbons in gas mixtures, as they lack the necessary selective separation properties and stability during pyrolysis.
Innovation Solution
A two-stage process involving surface passivation of copolymers with a highly alkaline alcohol solution followed by gradual pyrolysis to develop microporosity and high surface area values, resulting in microporous carbon materials with specific elemental compositions and morphologies that enable efficient chromatographic separation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If direct pyrolysis of copolymers is performed without surface passivation, then the process is simpler and faster, but the material deforms and loses structural integrity during pyrolysis
Solution Approach 1:
The patent applies surface passivation treatment before pyrolysis to prevent material deformation. The copolymer surface is chemically modified in advance by reacting with alkali metal hydroxides, creating a stable surface layer that prevents deformation during subsequent high-temperature pyrolysis processing.
2Reliability
If surface passivation with highly alkaline alcohol solution is applied, then structural stability during pyrolysis is improved, but the manufacturing process becomes more complex and time-consuming
Solution Approach 1:
The patent optimizes the passivation process by controlling specific parameters: using alkali metal hydroxides with concentrations of 0.1-10 M, maintaining reaction temperatures of 20-80°C, and controlling reaction times of 0.5-16 hours. These parameter optimizations balance the need for structural stability with reasonable process complexity.
3Area of stationary object
If pyrolysis temperature is increased to develop microporosity, then surface area and separation efficiency are improved, but material deformation and structural collapse increase
Solution Approach 1:
The patent applies surface passivation as a protective measure before pyrolysis. The chemical modification of the copolymer surface creates a stabilized structure that acts as a cushion against deformation during high-temperature pyrolysis, enabling the development of microporosity and high surface area while maintaining structural integrity.
4Quantity of substance
If copolymer composition is optimized for high carbon content, then microporous carbon quality is improved, but the range of applicable copolymers is limited
Solution Approach 1:
The patent demonstrates universality by showing that the surface passivation method can be applied to multiple copolymer types including polyvinylidene chloride, polyvinylidene fluoride, and their copolymers with various comonomers. The method achieves high carbon content microporous carbon from diverse copolymer feedstocks, making the process broadly applicable.
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 process produces microporous carbon materials with high carbon content and controlled oxygen levels, maintaining shape and size, effectively separating nitrogen and other gases, such as hydrogen sulfide and carbon dioxide, through adsorption-desorption processes with enhanced efficiency and stability.
Implementation Method 1
surface passivation of the material by chemical attack in a highly alkaline alcohol solution with the aim of effecting a precarbonization on the surface of the copolymer
Implementation Method 2
effecting a precarbonization on the surface of the copolymer, so that during the pyrolysis process it is not deformed, and gradually develops the microporosity
Implementation Method 3
The second stage consists of the gradual pyrolysis of the passivated copolymer with the aim of developing microporosity and high surface area values
Implementation Method 4
during the melting and the dehydrohalogenation of the passivated copolymer they prevent deformation of the material
Implementation Method 5
allows it to take it as a base to develop technologies for the separation of these components through adsorption-desorption processes
Implementation Method 6
The microporous carbon material presents the highly feasible quality of the chromatographic separation of nitrogen in mixtures with gases
Data Source
AI summary
The present invention relates to a process for the manufacture of microporous carbon materials to perform selective separations of nitrogen in gas mixtures such as hydrogen sulfide, carbon dioxide, methane and C2, C3 and C4+ hydrocarbons, with high efficiency, shaped of microspheres or cylinders from copolymers of poly (vinylidene chloride-co-methyl acrylate) with density of 1.3 to 1.85 g/cm.sup.3 or poly (vinylidene chloride-co-vinyl chloride) with density of 1.3 to 1.85 g/cm.sup.3, using two stages. The first stage consists of a surface passivation of the material by chemical attack in a highly alkaline alcohol solution, with the aim of effecting a precarbonization on the surface of the copolymer that during the pyrolysis process is not deformed and gradually develops microporosity. The material of the first stage presents, in the layer, percentages between 55% to 85% carbon, between 5% to 20% oxygen, and between 10% to 40% chlorine. The interior of the material presents lower percentages of carbon, between 30% to 65%, oxygen in the amount of between 2% to 6%, and chlorine in the amount of between 30% to 60%. The second stage consists of the gradual pyrolysis of the passivated copolymer, with the aim of developing microporosity and high surface area values; as well as during the melting and gas dehydrohalogenation stages thereof, the deformation of the material is avoided. The morphology of the copolymers are microspheres of 125 to 225 micrometers, or cylinders of 4 mm in height and 3 mm in diameter, which after pyrolysis reduce its size by 35% with respect to the initial one. The material of the second stage, which is already microporous carbon material, presents in the layer percentages between 90% to 100% carbon and between 10% to 0% oxygen.