Unsupported Ionic Liquid Catalyst for Low-Temperature Heptane Disproportionation
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Solution Overview
Problem
Current processes for hydrocarbon disproportionation and isomerization, particularly using ionic liquids, face challenges such as high temperatures, catalyst deactivation, and excessive use of expensive ionic liquids, leading to inefficient conversion rates and unclear product compositions.
Innovation Solution
A hydrocarbon conversion process utilizing an unsupported ionic liquid catalyst with a carbocation promoter, operating at temperatures below 200°C, which achieves significant disproportionation and isomerization of C7 alkanes with reduced ionic liquid usage, producing a product mixture with enhanced Reid vapor pressure and octane number ranges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If conventional catalysts (zeolites, sulfated zirconias, AlCl2/SiO2, ionic solids, platinum on Al2O3/Ga2O3 supports) are used for hydrocarbon disproportionation, then the desired paraffin disproportionation reaction is produced, but elevated temperatures (120-450°C) are required to carry out the transformation
Solution Approach 1:
The patent changes the chemical parameters of the catalyst system by using ionic liquids with specific cations (trimethylammonium, tetramethylammonium, pentamethylammonium) and anions (AlCl4-, Al2Cl7-, GaCl4-) to enable the disproportionation reaction to proceed at lower temperatures (below 200°C) while maintaining high conversion rates. This parameter change in catalyst composition directly resolves the contradiction between temperature and productivity.
2Temperature
If HF/TiF4 system is used for disproportionation at 51°C, then low temperature operation is achieved, but dangerous HF is utilized
Solution Approach 1:
The patent replaces the hazardous HF/TiF4 catalyst system with ionic liquids that can be easily disposed of or recycled. The ionic liquids used (trimethylammonium, tetramethylammonium, pentamethylammonium salts) are non-hazardous alternatives that maintain low-temperature operation without the safety risks associated with HF, thus resolving the contradiction between low temperature operation and harmful factor elimination.
3Temperature
If supported ionic liquid is used as catalyst, then active catalysis from 85-125°C is achieved, but the ionic liquid is deactivated by leaching from the support
Solution Approach 1:
The patent extracts the ionic liquid from the supported catalyst configuration and uses it as a homogeneous liquid catalyst without any solid support. This eliminates the leaching problem that causes deactivation in supported systems, while maintaining the low-temperature activity (85-125°C) of ionic liquid catalysts. The ionic liquid remains in the liquid phase throughout the reaction, preventing loss of catalytic activity.
4Productivity
If supported ionic liquid is used as catalyst, then catalytic activity is achieved, but the support increases catalyst cost and may result in chemical reaction with acidic ionic liquid over time
Solution Approach 1:
The patent removes the support component from the catalyst system entirely, using pure ionic liquids (trimethylammonium, tetramethylammonium, pentamethylammonium salts) as homogeneous catalysts. This extraction of the support eliminates both the cost increase and the potential chemical reactions between the support and acidic ionic liquid, while maintaining full catalytic activity for the disproportionation reaction.
5Productivity
If Brønsted acidic ionic liquid with stoichiometric acid concentration is used, then high acid concentration catalysis is achieved, but the acid concentration is quite high and stoichiometric
Solution Approach 1:
The patent changes the acid concentration parameter by using ionic liquids with controlled acid content. Instead of stoichiometric acid concentrations (e.g., 3.0-4.1 M HCl in trimethylammonium chloroaluminate), the patent employs ionic liquids with lower, controlled acid concentrations that still provide sufficient catalytic activity. This parameter adjustment reduces the quantity of hazardous acid while maintaining productive reaction rates.
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 high conversion rates with reduced ionic liquid consumption, producing a product mixture with at least 3 wt% C8+ alkanes and 3 wt% C6− alkanes within 1 hour, and improved octane numbers, while maintaining low reactivity and stability.
Implementation Method 1
contacting the hydrocarbon feed with a liquid catalyst in a reaction zone under disproportionation conditions to form a product mixture comprising at least about 3 wt % C8+ alkanes in 1 hr based on the C7 alkanes in the hydrocarbon feed
Implementation Method 2
The liquid catalyst comprises an unsupported ionic liquid and a carbocation promoter
Data Source
AI summary
Processes for the disproportionation and isomerization of a C7 hydrocarbon feed using a liquid catalyst comprising an ionic liquid and a carbocation promoter are described. The ionic liquid is unsupported, and the reactions occur at temperatures below about 200° C.