Fluid Catalytic Cracking Propene Selectivity via C4-C5 Hydrocarbon Blending
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Solution Overview
Problem
Dual reactor systems for catalytic cracking often produce undesirably high yields of butene compared to propene, which is more valuable, due to the inherent composition of feeds like polymer naphtha, leading to a need for improved selectivity to maximize propene production.
Innovation Solution
Incorporating C4-C5 hydrocarbons, particularly C4 and C5 alkenes like butene and pentene, into the feed of a second riser reactor to shift the reaction equilibrium and enhance propene selectivity, while minimizing recycle rates and gas yields.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If polymer naphtha is used as feed in dual reactor system, then cracking efficiency is improved, but butene yield increases undesirably while propene yield decreases
Solution Approach 1:
The patent changes the chemical composition parameters of the feed by blending polymer naphtha with specific ratios of C4-C5 hydrocarbons (particularly butene and pentene). This parameter modification shifts the reaction equilibrium to favor propene production while maintaining cracking efficiency, resolving the contradiction between productivity and unwanted butene accumulation.
Solution Approach 2:
The patent introduces C4-C5 hydrocarbons as intermediary substances that mediate the cracking reaction. These intermediaries participate in the reaction equilibrium, converting unwanted butene into desired propene through chemical interaction, thereby reducing butene yield while preserving cracking efficiency.
2Quantity of substance
If C4-C5 hydrocarbons are added to maximize propene production, then propene selectivity is improved, but feed composition complexity increases
Solution Approach 1:
The patent modifies feed composition parameters by incorporating C4-C5 hydrocarbons at specific concentrations (e.g., 1-50 wt% based on total feed). This parameter adjustment optimizes propene selectivity while maintaining manageable feed complexity through defined compositional ranges rather than requiring complex multi-component feeds.
3Ease of operation
If dual reactor system is used to tailor cracking conditions, then product distribution control is improved, but capital costs increase
Solution Approach 1:
The patent optimizes operating parameters (temperature, pressure, catalyst type) within the dual reactor system to enhance propene selectivity. By adjusting these parameters rather than increasing system complexity, the patent achieves better product distribution control while managing capital costs through efficient use of existing reactor infrastructure.
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 effectively increases propene selectivity and reduces by-product yields, such as butene, resulting in higher propene production with minimized recycle and gas yields, optimizing the dual reactor system's performance.
Implementation Method 1
providing a catalyst to at least one of the first and second riser reactors
Implementation Method 2
providing a first feed having a boiling point of about 180-about 800° C. to a first riser reactor... operating at a temperature of about 150-about 580° C.
Data Source
AI summary
One exemplary embodiment can be a process for fluid catalytic cracking. The process may include providing a first feed having a boiling point of about 180-about 800° C. to a first riser reactor, and providing a second feed having first and second parts to a second reactor. Typically, the first part includes one or more C5-C12 hydrocarbons and a second part includes one or more C4-C5 hydrocarbons. Generally, an effective amount of the second part is combined with the first part to maximize production of propene.