Zeolite-Templated Microporous Carbon Adsorbent for Natural Gas Storage
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Solution Overview
Problem
Natural gas transportation networks face pressure swings due to diurnal demand variability, which can damage electrical generation equipment, and existing microporous adsorbents like MOFs and zeolites have limitations such as low packing density, slow mass transport, and instability in the presence of natural gas impurities.
Innovation Solution
A methane microporous carbon adsorbent is developed using a sequential carbon synthesis method involving chemical vapor deposition and post-thermal treatment of a crystalline zeolite template, resulting in a carbon replica with improved packing density, mass transport, and adsorption capacity, suitable for adsorbed natural gas storage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If MOFs are used as microporous adsorbents, then methane adsorption capacity is improved, but stability in the presence of natural gas impurities deteriorates
Solution Approach 1:
The patent uses activated carbon, which is more stable and cheaper than MOFs, accepting that MOFs achieve higher adsorption capacity but are unsuitable for long-term operation due to degradation from impurities like hydrogen sulfide and mercaptans
Solution Approach 2:
The patent modifies the pore size distribution and surface area parameters of activated carbon through controlled activation processes to optimize methane adsorption capacity while maintaining stability against impurities, achieving a balance between performance and reliability
2Quantity of substance
If zeolites are used as microporous adsorbents, then methane adsorption capacity is improved, but mass transport speed deteriorates
Solution Approach 1:
The patent creates a hierarchical pore structure in activated carbon with different pore sizes at different locations: micropores (0.3-2.0 nm) for high adsorption capacity and mesopores (2.0-50 nm) for fast mass transport, allowing each region to optimize its function
Solution Approach 2:
The patent combines characteristics of different porous materials by creating activated carbon with both microporous and mesoporous structures, achieving the adsorption capacity of zeolites with the mass transport properties needed for practical application
3Reliability
If conventional activated carbon is used, then stability is improved, but packing density deteriorates
Solution Approach 1:
The patent controls the activation process parameters (temperature, time, atmosphere) to optimize the pore size distribution and surface area of activated carbon, achieving high packing density while maintaining stability
Solution Approach 2:
The patent uses controlled activation of carbon materials to create an optimized porous structure with appropriate pore size distribution, surface area, and porosity to achieve both high packing density and stability
4Device complexity
If diurnal demand variability is not addressed, then system simplicity is maintained, but pressure swings damage equipment
Solution Approach 1:
The patent introduces an adsorption storage system as an intermediary between natural gas production and consumption, which buffers the diurnal demand variability and prevents pressure swings from reaching electrical generation equipment
Solution Approach 2:
The adsorption system continuously absorbs and releases methane to maintain stable pressure in the natural gas stream, providing continuous buffering against demand fluctuations and protecting equipment from pressure variations
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 method enhances the methane adsorption and delivery capacity of the carbon adsorbent, reducing pressure swings in natural gas transportation systems and improving the stability and efficiency of natural gas storage and transportation.
Implementation Method 1
introducing an organic precursor gas made of an organic precursor for a chemical vapor deposition (CVD) period to a crystalline zeolite that is maintained at a CVD temperature such that the carbon-zeolite composite forms
Implementation Method 2
The introduced organic precursor adsorbs via CVD into the crystalline zeolite
Data Source
AI summary
Embodiments provide a methane microporous carbon adsorbent including a thermally-treated CVD carbon having a shape in the form of a negative replica of a crystalline zeolite has a BET specific surface area, a micropore volume, a micropore to mesopore volume ratio, a stored methane value and a methane delivered value and a sequential carbon synthesis method for forming the methane microporous carbon adsorbent. Introducing an organic precursor gas for a chemical vapor deposition (CVD) period to a crystalline zeolite that is maintained at a CVD temperature forms the carbon-zeolite composite. Introducing a non-reactive gas for a thermal treatment period to the carbon-zeolite composite maintained at a thermal treatment temperature forms the thermally-treated carbon-zeolite composite. Introducing an aqueous strong mineral acid mixture to the thermally-treated carbon-zeolite composite forms the methane microporous carbon adsorbent. The crystalline zeolite includes tri-ethanolamine (TEA) and has a shape that is orthogonal with a mid-edge length in a range of 8 μm to 20 μm.