5A Molecular Sieve Separation for Deep Source Rock n-Alkane Isotopes
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Solution Overview
Problem
Existing analytical methods fail to accurately analyze C8-C13 fractions and carbon isotopes in deep and ultra-deep source rocks due to overlapping chromatographic peaks and the loss of light hydrocarbon components during Soxhlet extraction, leading to unreliable quantitation and carbon isotope analysis.
Innovation Solution
A system and method utilizing a pyrolysis device, 5A molecular sieve column, and programmable heating system for on-line separation and analysis of light n-alkane components and carbon isotopes, including a column box with chromatographic columns and a mass spectrometer, which allows for precise desorption and separation of n-alkanes based on molecular weight and boiling point.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If conventional Soxhlet extraction and offline analysis methods are used, then the analysis process is simple and equipment requirements are low, but light hydrocarbon components (C13−) are completely volatilized and lost, and only C13 and C13+ components can be obtained
Solution Approach 1:
The patent changes the extraction parameters by using pyrolysis temperature control (280-320℃) instead of conventional Soxhlet extraction conditions. This parameter change allows light hydrocarbon components to be converted into pyrolysis products that can be retained and analyzed, preventing their volatilization loss while enabling the analysis of C13- components that were previously lost
Solution Approach 2:
The patent introduces a molecular sieve column as an intermediary substance that selectively adsorbs light hydrocarbon components from the pyrolysis products. This intermediary enables the separation and retention of C13- components that would otherwise be lost, allowing them to be concentrated and analyzed without complete volatilization
2Measurement precision
If conventional chromatographic separation is used, then the separation process is simple, but chromatographic peaks overlap significantly, leading to large errors in quantitation and carbon isotope analysis
Solution Approach 1:
The patent segments the separation process into two distinct stages: first using a molecular sieve column to separate light hydrocarbon components (C1-C13) from heavier components, then using a non-polar chromatographic column to further separate the light components. This segmentation eliminates peak overlap by dividing the complex separation into manageable steps, significantly improving quantitation accuracy
Solution Approach 2:
The molecular sieve column acts as an intermediary separation stage between the sample injection and the final detection. It pre-separates the complex mixture into fractions, reducing the complexity of the subsequent chromatographic separation and eliminating peak overlap that would otherwise occur in a single-stage system
3Productivity
If conventional offline step-by-step analysis is used, then each analysis step can be performed with simple equipment, but the analysis time spans weeks and requires multiple manual operations
Solution Approach 1:
The patent merges pyrolysis, separation, and analysis functions into a single integrated online system. The pyrolysis furnace directly connects to the dual-column chromatographic system, which connects to the detector, allowing the entire analysis process to occur continuously in one workflow. This merging eliminates the need for manual transfer of samples between equipment and reduces analysis time from weeks to hours
Solution Approach 2:
The patent establishes continuous operation by maintaining constant flow of carrier gas through the system and implementing continuous pyrolysis-separation-detection. The online system allows samples to be continuously introduced, pyrolyzed, separated, and analyzed without interruption or manual intervention, maximizing productivity and eliminating the time losses associated with offline batch processing
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 achieves accurate and efficient analysis of n-alkane composition and isotopes, reducing analysis time from weeks to hours, and provides reliable biomarker parameters for maturity and oil-source correlation, with improved separation and reduced overlap of chromatographic peaks.
Implementation Method 1
n-alkane components in the pyrolysis product are adsorbed by the 5A molecular sieve column and retained in the 5A molecular sieve column
Implementation Method 2
a 5A molecular sieve column
Implementation Method 3
the n-alkane components adsorbed on the 5A molecular sieve column are successively desorbed according to molecular weight and boiling point
Implementation Method 4
a programmable heating system
Implementation Method 5
a first chromatographic column, and a second chromatographic column
Implementation Method 6
separated by column chromatography and undergo the 5A molecular sieve adsorption or urea complexation
Implementation Method 7
an outlet of the second chromatographic column is connected to a mass spectrometer
Data Source
AI summary
A method for analyzing light n-alkane components and carbon isotopes in deep and ultra-deep source rocks includes: (S1) subjecting a 5A molecular sieve column to aging; (S2) pyrolyzing a source rock; and allowing a pyrolysis product to enter the 5A molecular sieve column; where n-alkanes are adsorbed and retained by the 5A molecular sieve column; allowing an outflow to pass through a fractionation plate and an empty column or a weak polarity column to be discharged; and (S3) performing programmed heating such that the n-alkanes adsorbed on the 5A molecular sieve column are successively desorbed according to molecular weight, and then pass through the fractionation plate and the HP-5 or DB-5 column to enter a mass spectrometer for composition analysis or isotopic analysis. An analysis system is further provided.