Molten Salt Catalyst for Lactic Acid to Acrylic Acid Conversion
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Solution Overview
Problem
Current methods for producing acrylic acid from lactic acid in the liquid phase have low yield and selectivity, and existing technologies rely on fossil-derived resources, contributing to greenhouse emissions and resource scarcity.
Innovation Solution
A three-step method involving a feed stream of lactic acid or lactide, where the first step uses a molten salt catalyst with a bromide anion to produce 2-bromopropionic acid, followed by conversion to a mixture of acrylic acid and 3-bromopropionic acid using another molten salt catalyst, and finally to acrylic acid using an amine, significantly enhancing yield and selectivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If gas phase dehydration of lactic acid is used, then the process is simpler, but the yield and selectivity of acrylic acid are low
Solution Approach 1:
The patent changes the physical state parameter from gas phase to liquid phase dehydration, and modifies the catalyst state from conventional to molten salt, thereby improving both yield and selectivity while maintaining process feasibility
Solution Approach 2:
The patent uses composite molten salt catalysts combining multiple salts (e.g., LiCl-KCl-CaCl2 or LiCl-KCl-SrCl2) with specific molar ratios to achieve synergistic effects that enhance acrylic acid production beyond what single catalysts can provide
2Productivity
If liquid phase dehydration is used, then yield and selectivity improve, but the process complexity increases
Solution Approach 1:
The patent segments the dehydration process into two distinct reaction steps: first forming 2-bromopropionic acid intermediate, then converting to acrylic acid. This segmentation allows optimization of each step independently, managing complexity while maximizing yield
Solution Approach 2:
The patent introduces 2-bromopropionic acid as an intermediate compound that facilitates the conversion from lactic acid to acrylic acid, enabling a more efficient reaction pathway with higher selectivity
3Device complexity
If one-step process is used, then the process is simpler, but overall acrylic acid yield is low
Solution Approach 1:
The patent divides the dehydration process into two sequential steps with different catalysts optimized for each step, achieving 67-75% overall yield compared to 22-52% in one-step processes
Solution Approach 2:
The patent performs preliminary bromination to form 2-bromopropionic acid intermediate before final dehydration to acrylic acid, preparing the substrate in advance for more efficient conversion and higher overall yield
4Ease of manufacture
If fossil-derived propylene oxidation is used, then production cost is competitive, but environmental impact increases
Solution Approach 1:
The patent changes the feedstock source from fossil-derived propylene to renewable lactic acid, and modifies the reaction pathway from oxidation to dehydration, eliminating greenhouse emissions while maintaining cost competitiveness through efficient catalysis
Solution Approach 2:
The patent converts the typically harmful oxidation process into a beneficial dehydration reaction that produces water as the only byproduct, transforming an environmentally damaging pathway into a sustainable one
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 method achieves a higher overall acrylic acid yield and selectivity compared to one-step processes, utilizing renewable resources and reducing environmental impact by minimizing energy use and emissions.
Implementation Method 1
contacting the feed stream with a molten salt catalyst comprising a protic ionic liquid (PIL), which contains a bromide anion (Br-)
Data Source
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Figure 2
AI summary
A method of making acrylic acid in liquid phase by contacting a feed stream containing lactic acid, lactide, or mixtures thereof with a molten salt catalyst comprising a protic ionic liquid (PIL), which contains a bromide anion (Br-), is provided.