Hydrocarboxylation of Formaldehyde Using Solid Acid Catalysts
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Solution Overview
Problem
Current methods for producing glycolic acid require high temperatures and pressures, expensive materials, and face challenges in separating glycolic acid from carboxylic acid due to their similar hydrophobicity, making purification difficult and costly.
Innovation Solution
A process involving the carbonylation of formaldehyde with carbon monoxide in the presence of a solid acid catalyst, using a hydrophobic solvent to separate glycolic acid from carboxylic acid, allowing for the recovery and recycling of carboxylic acid, thereby reducing costs and improving separation efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high temperature and pressure are used for carbonylation reaction, then reaction rate is improved, but equipment cost and safety requirements increase
Solution Approach 1:
The patent changes the physical state of the catalyst from liquid to solid form, which fundamentally alters the reaction conditions. The solid acid catalyst enables the reaction to proceed at moderate temperatures (50-150°C) and pressures (1-10 MPa) while maintaining high reaction rates, thus resolving the contradiction between productivity and device complexity
Solution Approach 2:
The patent employs a solid acid catalyst that can be easily separated and reused multiple times, replacing expensive special materials like hydrogen fluoride catalyst that require costly recovery systems. The solid catalyst acts as a disposable-like component that simplifies equipment requirements while maintaining productivity
2Stress or pressure
If hydrogen fluoride is used as catalyst, then reaction proceeds at lower pressure, but expensive materials and recovery schemes are required
Solution Approach 1:
The patent replaces hydrogen fluoride catalyst with solid acid catalysts such as sulfonic acid resins, heteropolyacids, or solid sulfates that are inexpensive, stable, and do not require special materials of construction. These solid catalysts can be handled with ordinary equipment, eliminating the need for expensive corrosion-resistant materials and complex recovery schemes
3Quantity of substance
If aqueous formaldehyde is used as starting material, then material cost is reduced, but water inhibits reaction rate and complicates purification
Solution Approach 1:
The patent uses a solid acid catalyst that selectively catalyzes the carbonylation reaction of formaldehyde even in the presence of water. The solid catalyst surface provides a hydrophobic environment that excludes water from the active sites, allowing the reaction to proceed at high rates with aqueous formaldehyde feeds without water inhibition
4Manufacturing precision
If distillation is used to separate glycolic acid from carboxylic acid, then separation is attempted, but glycolic acid reacts with carboxylic acid at process temperatures
Solution Approach 1:
The patent employs extraction chromatography where the stationary phase is a solid adsorbent and the mobile phase is a solvent system that selectively transports glycolic acid. This chromatographic separation occurs at ambient or low temperatures, avoiding the thermal degradation that occurs in distillation, thus resolving the contradiction between separation purity and chemical stability
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 enables the production of glycolic acid at moderate temperatures and pressures, facilitating easy separation and recycling, thus enhancing the economic viability and efficiency of the glycolic acid production.
Implementation Method 1
feeding carbon monoxide, aqueous formaldehyde, and a carboxylic acid comprising 3-6 carbon atoms to a hydrocarboxylation reaction zone comprising a solid acid catalyst to produce an effluent comprising esters of glycolic and carboxylic acids
Implementation Method 2
recovering the carboxylic acid from the hydrolyzed mixture by extracting the hydrolyzed mixture with a hydrophobic solvent selected from at least one of the group consisting of esters having from 4 to 20 carbon atoms, ethers having from 4 to 20 carbon atoms, ketones having from 4 to 20 carbon atoms, and hydrocarbons having from 6 to 20 carbon atoms to form an aqueous raffinate phase comprising a major amount of the glycolic acid contained in the hydrolyzed mixture and an organic extract phase comprising a major amount of the carboxylic acid contained in the hydrolyzed mixture
Implementation Method 3
hydrolyzing the effluent to produce a hydrolyzed mixture comprising glycolic acid and the carboxylic acid
Data Source
AI summary
Disclosed is a process for the production and purification of glycolic acid or glycolic acid derivatives by the carbonylation of formaldehyde in the presence of a solid acid catalyst and a carboxylic acid. This invention discloses hydrocarboxylations and corresponding glycolic acid separations wherein the glycolic acid stream is readily removed from the carboxylic acid and the carboxylic acid is recycled.