Composite Dehydration Catalyst for Hydroxypropionic Acid Conversion
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Solution Overview
Problem
Current methods for dehydrating hydroxypropionic acid to acrylic acid suffer from low yields, high side product formation, long residence times, and catalyst deactivation, making them commercially unviable.
Innovation Solution
A dehydration catalyst comprising amorphous phosphate salts, crystalline phosphate salts, and non-phosphate salts, which are chemically inert to each other, is used in the presence of water vapor to achieve high yield and selectivity for acrylic acid with improved catalyst longevity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional dehydration catalysts (sulfate salts, phosphate salts, bases, zeolites, metal oxides) are used to dehydrate lactic acid or lactate to acrylic acid, then the reaction can proceed, but the yield of acrylic acid is limited (not exceeding 70% at short residence times) and significant amounts of side products are formed
Solution Approach 1:
The patent employs a composite catalyst system comprising multiple components: amorphous phosphate salts (e.g., (NH4)2HPO4, KH2PO4), crystalline phosphate salts (e.g., CaHPO4, BaHPO4), and non-phosphate salts (e.g., BaSO4, SrSO4). This composite approach combines the strengths of different catalyst types to achieve high acrylic acid yield (≥85%) while minimizing side product formation, resolving the contradiction between productivity and harmful byproducts
2Productivity
If conventional catalysts are used for dehydration, then the reaction can occur, but long residence times are required and catalyst deactivation occurs rapidly
Solution Approach 1:
The patent optimizes reaction parameters including temperature (300-400°C), pressure (0.1-10 bar), and residence time (0.1-10 seconds) to achieve high conversion efficiency. The catalyst formulation with specific ratios of amorphous to crystalline phosphate salts maintains stability and activity over extended periods, reducing deactivation and enabling shorter residence times while maintaining high productivity
3Productivity
If high temperature is used to increase reaction rate, then productivity improves, but catalyst deactivation accelerates and side products increase
Solution Approach 1:
The catalyst design incorporates amorphous phosphate salts with high surface area and reactive sites for rapid reaction at moderate temperatures, combined with crystalline phosphate salts that provide structural stability and resistance to deactivation. This spatial and functional differentiation within the catalyst system enables maintaining high reaction rates while preserving catalyst integrity, avoiding the need for excessively high temperatures that would accelerate deactivation
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 catalyst system achieves high yield and selectivity for acrylic acid with low side products, efficiency in short residence times, and extended catalyst longevity, addressing the deficiencies of prior art processes.
Implementation Method 1
Catalysts for the dehydration of hydroxypropionic acid, hydroxypropionic acid derivatives, or mixtures thereof to acrylic acid, acrylic acid derivatives, or mixtures thereof
Implementation Method 2
The invention also relates to methods of making such dehydration catalysts. Technical Solution: A dehydration catalyst comprising amorphous phosphate salts, crystalline phosphate salts, and non-phosphate salts, which are chemically inert to each other, is used in the presence of water vapor
Data Source
AI summary
Hydroxypropionic acid, hydroxypropionic acid derivatives, or mixtures thereof are dehydrated using a catalyst and a method to produce bio-acrylic acid, acrylic acid derivatives, or mixtures thereof. A method to produce the dehydration catalyst is also provided.