Two-Step Catalytic Cracking for BTX and Lower Olefins
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Solution Overview
Problem
Conventional methods for producing BTX and lower olefins from light cycle oil (LCO) face inefficiencies due to the presence of non-aromatic components, resulting in low yields and the generation of low-value gas fractions as by-products.
Innovation Solution
A method involving two catalytic cracking steps with different contact times for stock oils with varying aromatic content, using a catalytic cracking catalyst to maximize the yield of BTX and lower olefins while minimizing by-product gas production, by optimizing the contact time and aromatic content in each step.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional catalytic cracking methods are used to produce BTX and lower olefins from LCO, then aromatic components can be converted to BTX, but non-aromatic components generate low-value gas fractions as by-products and reduce overall yield
Solution Approach 1:
The catalytic cracking process is divided into two distinct steps with different contact times: a first step with a longer contact time (0.5-5.0 seconds) optimized for converting aromatic components to BTX, and a second step with a shorter contact time (0.1-0.5 seconds) optimized for converting non-aromatic components to lower olefins. This segmentation allows each step to target specific feedstock components, preventing the formation of low-value gas fractions while maximizing the yield of high-value products.
Solution Approach 2:
The invention changes the contact time parameter between the feedstock and catalyst across different process steps. By setting the contact time in the first step to 0.5-5.0 seconds and in the second step to 0.1-0.5 seconds, the process optimizes product distribution. This parameter change enables selective conversion: aromatic components undergo complete cracking to BTX in the first step, while non-aromatic components are converted to lower olefins in the second step without excessive cracking to gas fractions.
2Productivity
If the contact time between stock oil and catalytic cracking catalyst is increased to improve conversion of aromatic components, then BTX yield increases, but over-cracking occurs producing more gas by-products
Solution Approach 1:
The process segments the conversion of aromatic and non-aromatic components into separate steps with different contact times. The first step uses a longer contact time (0.5-5.0 seconds) specifically for aromatic component conversion to BTX, while the second step uses a shorter contact time (0.1-0.5 seconds) for non-aromatic component conversion. This prevents over-cracking and gas fraction formation while maintaining high BTX yield.
Solution Approach 2:
The invention applies partial action by using different contact times for different feedstock components. The first step applies a longer contact time (excessive for non-aromatics) only to aromatic components to ensure complete conversion to BTX, while the second step applies a shorter contact time (partial conversion) to non-aromatic components to produce lower olefins without over-cracking to gas fractions.
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 yield of BTX and lower olefins while significantly reducing the production of low-value gas fractions, effectively utilizing non-aromatic components as raw materials for high-value petrochemical products.
Implementation Method 1
a first catalytic cracking step of bringing one stock oil A among the stock oils into contact with a catalytic cracking catalyst; a second catalytic cracking step of bringing one stock oil B, having an aromatic component content smaller than that of the stock oil A, among the stock oils into contact with the catalytic cracking catalyst
Data Source
AI summary
A method of producing a lower olefin and BTX from stock oils selected from at least two kinds of oils is provided. The method includes a first catalytic cracking step of bringing one stock oil A into contact with a catalytic cracking catalyst; a second catalytic cracking step of bringing one stock oil B, having an aromatic component content smaller than that of the stock oil A, into contact with the catalytic cracking catalyst; and a separation and collection step of collecting the lower olefins and BTX from a product generated in the first and second catalytic cracking steps. A contact time A during which the stock oil A is in contact with the catalytic cracking catalyst in the first catalytic cracking step is longer than a contact time B during which the stock oil B is in contact with the catalytic cracking catalyst in the second catalytic cracking step.