Triglyceride Hydroconversion for Light Olefin Selectivity
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Solution Overview
Problem
Current processes for producing light olefins from triglycerides derived from biomass face challenges such as excessive temperature rise in hydroconversion reactors and reduced selectivity in catalytic cracking, leading to undesirable by-products and impaired yield of ethylene and propylene.
Innovation Solution
A combined process of hydroconversion and fluid catalytic cracking, where the liquid fraction of paraffinic hydrocarbons from triglycerides is separated and further processed on a zeolite-rich catalyst, specifically ZSM-5, to maximize the production of ethylene and propylene, achieving high conversion and selectivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If hydroconversion reactions are performed in an adiabatic reactor with increasing temperature along the catalyst bed, then the hydroconversion of triglycerides proceeds, but excessive temperature rise occurs leading to undesirable effects
Solution Approach 1:
The reactor is divided into multiple catalyst beds with interspersed cooling zones or recycle stream injection points between them. This segmentation allows the exothermic hydroconversion reactions to occur in controlled stages, preventing excessive temperature rise in any single bed while maintaining overall conversion efficiency.
Solution Approach 2:
A recycle stream is introduced as an intermediary between catalyst beds to absorb excess heat and moderate the temperature profile. This intermediate stream acts as a thermal buffer, reducing the rate of temperature rise in subsequent beds while carrying reactants forward for continued conversion.
2Productivity
If conventional catalytic cracking is applied to organic oils from biomass, then fuels are produced, but selectivity for light olefins is reduced leading to increased heavy products and by-products
Solution Approach 1:
The catalytic cracking process parameters are optimized specifically for light olefin production, including adjusting temperature, pressure, residence time, and catalyst-to-feed ratio. These parameter changes shift the reaction selectivity toward ethylene and propylene while minimizing heavy product formation.
Solution Approach 2:
A composite catalyst system is employed that combines multiple catalytic components with complementary functions. This composite catalyst enhances selectivity for light olefins through synergistic effects, promoting desired cracking reactions while suppressing side reactions that lead to heavy products and coke.
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 process achieves greater than 80% conversion and selectivity for light olefins, primarily ethylene and propylene, while minimizing the production of heavy products and undesirable by-products, such as coke and fuel gas, thereby enhancing the economic value of the petrochemical products.
Implementation Method 1
a process of hydroconversion of organic oils, obtained from vegetable and/or animal biomass, comprises the reaction of hydrogen with the fatty acids making up the molecules of the triglycerides to produce paraffinic hydrocarbons
Implementation Method 2
the catalytic cracking of this liquid fraction in process conditions for maximizing the production of ethylene and propylene
Implementation Method 3
the highly exothermic character of the reactions of hydroconversion of the triglycerides of the feed in a reactor that operates adiabatically with increasing temperature along the catalyst bed
Data Source
AI summary
The process combines hydroconversion and catalytic cracking starting from a feed containing triglycerides, at concentrations of fatty acids above 85%, which maximizes the yields of light olefins, chiefly ethylene and propylene, while reducing the yield of gasoline, with conversion greater than 80 wt. %.