Acrylic Acid Production from Lactide via Base Catalysis
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Solution Overview
Problem
Current production of acrylic acid is costly and inefficient, relying on expensive catalysts and high-temperature processes, with limited commercial viability for microbial fermentation and high raw material costs, and existing dehydration methods yield low acrylic acid from lactic acid.
Innovation Solution
A process using base catalysts like sodium methoxide to convert lactide and methyl acetate into methyl 2-acetoxypropionate, followed by pyrolysis to produce methyl acrylate and acetic acid, which are then transesterified to achieve technical grade acrylic acid, allowing for recycling and reducing water complications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional two-stage air oxidation of propylene is used to produce acrylic acid, then production capacity is achieved, but production cost is very high due to expensive catalysts and high-temperature processes
Solution Approach 1:
The invention changes the fundamental parameters of the process by switching from propylene oxidation to lactic acid dehydration. This involves changing the feedstock, reaction pathway, catalyst system, and operating conditions, thereby achieving acrylic acid production through a completely different chemical route that avoids the high costs of conventional catalysts and high-temperature oxidation
Solution Approach 2:
The invention employs inexpensive solid acid catalysts such as sulfonated carbon, Amberlyst-15, or Nafion instead of expensive Bi/Mo and Bi/V mixed metal oxide catalysts. These catalysts are readily available, cost-effective, and can be easily replaced or regenerated, significantly reducing the capital and operational costs of the process
2Productivity
If lactic acid is directly dehydrated to produce acrylic acid, then renewable resource utilization is achieved, but yield is low at approximately 55%
Solution Approach 1:
The invention introduces an intermediate compound (methyl lactate or its derivatives) in the reaction pathway from lactic acid to acrylic acid. By converting lactic acid to methyl lactate first, then to methyl 2-acetoxypropionate, and finally dehydrating to methyl acrylate which is hydrolyzed to acrylic acid, the process achieves near-quantitative yield while utilizing renewable lactic acid feedstock
3Reliability
If steam injection is used in reactors to control flammability, then safety is improved, but aqueous acrylic acid concentration drops to as low as 20%
Solution Approach 1:
The invention replaces steam injection with operation under inert or controlled atmosphere conditions. By using solid acid catalysts and conducting dehydration reactions in the liquid phase without introducing large amounts of steam, the process maintains safety while producing high-concentration acrylic acid products, eliminating the need for subsequent complex dewatering operations
4Manufacturing precision
If multiple vacuum distillations are performed to purify acrylic acid, then product purity is improved to >99%, but process complexity and capital cost increase significantly
Solution Approach 1:
The invention extracts and removes impurities selectively during the reaction and intermediate purification steps. By using solid acid catalysts that can be easily filtered off, and by performing selective distillations to remove specific by-products like water, methanol, and acetic acid at different stages, the process achieves high purity acrylic acid with simpler equipment compared to conventional multiple vacuum distillation systems
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 achieves high conversions and reduces costs by utilizing renewable resources, improving yield and efficiency in producing technical grade acrylic acid and methyl acrylate, with potential for further purification to glacial acrylic acid.
Implementation Method 1
A process using base catalysts like sodium methoxide to convert lactide and methyl acetate into methyl 2-acetoxypropionate
Implementation Method 2
followed by pyrolysis to produce methyl acrylate and acetic acid
Implementation Method 3
which are then transesterified to achieve technical grade acrylic acid
Data Source
AI summary
Technical grade acrylic acid derived from renewable resources utilizing a base catalyst system by a process including reacting lactide (or lactic acid oligomers) with methyl acetate to form methyl 2-acetoxypropionate in the presence of a base catalyst such as sodium methoxide, pyrolyzing the methyl 2-acetoxypropionate, with or without a catalyst, to methyl acrylate and acetic acid, transesterifying the mixture to acrylic acid and methyl acetate, separating and purifying the acrylic acid by distillation late in the presence of polymerization inhibitor(s). The disclosed process will produce a “green” (i.e. renewable resources derived) acrylic acid and/or methyl acrylate ester.