Catalytic Cracking Process for Isobutane and Light Aromatics Yield
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Solution Overview
Problem
Conventional catalytic cracking processes struggle to achieve high yields of isobutane and light aromatics, with existing methods often resulting in low olefin content in gasoline, making it difficult to utilize as raw materials in alkylation reactions.
Innovation Solution
A catalytic cracking process involving a feedstock oil with a polycyclic naphthene content greater than 25 wt%, subjected to sequential first and second catalytic cracking reactions under specific conditions, followed by hydrotreatment and recycling of hydrogenated tail oil, to enhance isobutane and light aromatics production.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If conventional catalytic cracking processes are used to produce gasoline with high octane number, then the octane number is improved, but the olefin content becomes excessively high (35-65 wt% in gasoline, 70 wt% in liquefied gas), making it unsuitable for alkylation reactions
Solution Approach 1:
The catalytic cracking process is divided into two distinct reaction zones: a first reaction zone for initial cracking and an second reaction zone for selective reactions. This segmentation allows different reaction conditions and catalysts to be applied in each zone, enabling control over product distribution to reduce olefin content while maintaining octane number.
Solution Approach 2:
A specific catalyst system is introduced as an intermediary in the second reaction zone to mediate the chemical transformations. The catalyst facilitates selective reactions that convert olefins into more stable products, thereby reducing olefin content in the final gasoline product while preserving the octane number.
2Productivity
If the olefin content in liquefied gas is increased to 70 wt%, then the gasoline yield is improved, but the content of butene becomes several times that of isobutane, making it difficult to use as raw material in alkylation
Solution Approach 1:
Different reaction conditions and catalyst properties are applied locally in different zones of the cracking system. The second reaction zone employs specific catalyst characteristics that promote isobutane formation over butene formation, thereby improving the quality of liquefied gas for alkylation applications while maintaining high gasoline yield.
Solution Approach 2:
Reaction parameters such as temperature, pressure, and catalyst-to-oil ratio are optimized and adjusted to favor isobutane production. By carefully controlling these parameters in the second reaction zone, the process achieves a more favorable isobutane-to-butene ratio suitable for alkylation feedstock.
3Productivity
If sequential first and second catalytic cracking reactions are performed under different reaction conditions, then the yield of isobutane and light aromatics is improved, but the process complexity increases
Solution Approach 1:
Two catalytic cracking reactions with different functions are merged into a single integrated reactor system. The first and second reaction zones are combined in one device, allowing sequential reactions to occur without requiring separate processing units, thereby reducing overall process complexity while maintaining high productivity for isobutane and light aromatics production.
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 process effectively increases the yield of isobutane and light aromatics, achieving a gasoline yield of over 40 wt% and improving the content of light aromatics in the gasoline product, while efficiently utilizing feedstock oil.
Implementation Method 1
contacting the catalytic cracking feedstock oil with a catalytic cracking catalyst in a catalytic cracking reactor, and subjecting the mixture to a first catalytic cracking reaction and a second catalytic cracking reaction
Implementation Method 2
the heavy fraction is subjected to a hydrotreatment to obtain a hydrogenated heavy fraction
Data Source
AI summary
Disclosed is a catalytic cracking process for producing isobutane and/or light aromatics in high yield, comprising the steps of: a) providing a catalytic cracking feedstock oil having a polycyclic naphthene content of greater than about 25 wt %; b) subjecting the catalytic cracking feedstock oil to a first catalytic cracking reaction and a second catalytic cracking reaction sequentially under different reaction conditions to obtain a catalytic cracking product; c) separating the resulting catalytic cracking product to obtain a liquefied gas fraction comprising isobutane and a gasoline fraction comprising light aromatics; and d) optionally, recovering isobutane from the liquefied gas fraction and/or recovering light aromatics from the gasoline fraction. The process can enable the production of isobutane and/or light aromatics in high yield.