Bio-Based Acrylic Acid Production for Fouling and Selectivity Control
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Solution Overview
Problem
Existing processes for producing acrylic acid from bio-raw materials face challenges such as low selectivity, fouling in reactors, and the production of low-boiling point by-products like acetaldehyde and carbon dioxide, which affect the purity and economic feasibility of the process.
Innovation Solution
A multi-step process involving cooling, compression, and absorption to separate and purify acrylic acid and acetaldehyde by-products, including steps to recover and condense materials, thereby reducing the need for absorbents and refrigerants, and enhancing the yield and purity of both products.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a gas-phase dehydration reaction using a solid catalyst is used to produce acrylic acid from lactic acid, then the reaction can proceed efficiently, but low-boiling point by-products such as acetaldehyde and carbon dioxide are produced together with acrylic acid, lowering acrylic acid selectivity
Solution Approach 1:
The patent divides the reaction system into multiple catalytic zones with different functions: a first catalyst layer for main dehydration reaction and a second catalyst layer for selective suppression of by-product formation. This segmentation allows each zone to perform its specific function, improving overall selectivity while maintaining productivity.
Solution Approach 2:
The patent applies different catalyst properties at different locations within the reactor. The first catalyst layer uses catalysts optimized for high dehydration activity, while the second catalyst layer uses catalysts specifically selected for suppressing acetaldehyde and carbon dioxide formation. This local differentiation of catalyst quality resolves the contradiction between productivity and selectivity.
2Productivity
If lactic acid is concentrated and a concentration increases, then dehydration occurs and oligomerization reaction occurs, but fouling occurs in the reactor and the reaction yield decreases
Solution Approach 1:
The patent introduces water into the reaction system before the oligomerization can occur. This preliminary action of adding water prevents the concentration increase that leads to fouling and oligomerization, thereby maintaining both high reaction yield and stable reactor operation throughout the process.
3Productivity
If by-products such as carbon monoxide, carbon dioxide and acetaldehyde are produced together with acrylic acid production, then the reaction proceeds, but the boiling point difference between by-products and acrylic acid makes separation difficult, lowering acrylic acid selectivity
Solution Approach 1:
The patent changes the physical parameters of the reaction system, specifically operating at elevated pressures (10-50 atm). This parameter change alters the relative volatility and solubility characteristics of the components, enabling more effective separation of by-products from acrylic acid through condensation and absorption processes, thereby improving both productivity and purity.
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 effectively separates and purifies acrylic acid and acetaldehyde, increasing their yield and purity, and enhances the economic feasibility of the bioprocess by commercializing these by-products as high-value products.
Implementation Method 1
separating a first low-boiling-point material including acetaldehyde (ACHO) and a first high-boiling-point material including acrylic acid (AA) by cooling a reaction product
Implementation Method 2
separating a condensed second low-boiling-point material including acetaldehyde (ACHO) and a second high-boiling-point material including acrylic acid (AA) by compressing the first low-boiling-point material including acetaldehyde (ACHO)
Implementation Method 3
separating a first incompressible material and a third low-boiling-point material including acetaldehyde (ACHO) by adding a second absorbent to the condensed second low-boiling-point material including acetaldehyde (ACHO)
Data Source
AI summary
The present application relates to a process for producing acrylic acid.