Polarised Hydroxyapatite Catalysis for Mild-Condition Urea Synthesis
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods for synthesizing urea from carbon dioxide (CO2) and ammonia (NH3) are energy-intensive and environmentally impactful, with conventional catalysts leading to high carbon footprints and inefficient single-step reactions that require complex and expensive materials, while lacking in yield and selectivity.
Innovation Solution
The use of a permanently polarised hydroxyapatite catalyst under mild conditions (95-120°C and 1 bar pressure) facilitates the fixation of CO2 and production of urea with 97% selectivity and approximately 30% efficiency without electrical currents or UV irradiation, utilizing a thermal stimulated polarisation process to enhance the catalyst's structural and electrical properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional metallic-based catalysts are used for CO2 conversion, then catalytic activity is achieved, but environmental impact increases and sustainability is reduced
Solution Approach 1:
The patent replaces expensive, environmentally harmful metallic-based catalysts with a cost-effective, sustainable calcium phosphate-based catalyst. The catalyst is designed to be non-toxic and environmentally benign, eliminating the need for noble metals while maintaining catalytic functionality for CO2 conversion reactions.
Solution Approach 2:
The patent modifies the catalyst's physical and chemical parameters by controlling particle size (nanoscale dimensions), surface area, and crystal structure of the calcium phosphate material. These parameter changes enhance catalytic activity while maintaining the environmentally friendly nature of the material, resolving the contradiction between activity and sustainability.
2Reliability
If energy-intensive conditions are applied to activate CO2, then CO2 conversion is achieved, but carbon emission balance becomes positive
Solution Approach 1:
The patent changes the reaction parameters by using mild temperatures and pressures enabled by the improved catalyst. The calcium phosphate catalyst lowers the activation energy required for CO2 conversion, allowing reactions to proceed under conditions that do not require excessive energy input, thereby maintaining a negative or neutral carbon emission balance.
Solution Approach 2:
The patent employs a sustainable, non-precious catalyst that enables CO2 conversion without requiring energy-intensive conditions. The catalyst's design allows efficient CO2 activation at lower temperatures and pressures, reducing the energy footprint and associated carbon emissions of the conversion process.
3Productivity
If single-step catalysed reactions are proposed, then reaction steps are reduced, but new limiting steps are established that hinder industrial viability
Solution Approach 1:
The patent segments the catalytic process into distinct functional steps, each addressed by specific catalyst properties. The calcium phosphate catalyst provides multiple active sites that facilitate different reaction steps sequentially, maintaining the benefits of a streamlined process while avoiding the creation of new limiting steps that would compromise industrial viability.
4Reliability
If conventional catalysts are used for urea synthesis, then reaction proceeds, but selectivity and yield are limited to ≤ 10%
Solution Approach 1:
The patent applies local quality by creating specific active sites on the calcium phosphate catalyst surface with tailored properties. The catalyst possesses localized regions with different chemical environments that selectively promote the formation of desired urea products while suppressing side reactions, thereby achieving high selectivity and yield exceeding 10%.
Solution Approach 2:
The patent optimizes catalyst parameters including surface area, porosity, and chemical composition to enhance selectivity. By controlling the particle size distribution and surface chemistry of the calcium phosphate catalyst, the reaction is directed toward high-yield urea production with minimal byproducts, achieving manufacturing precision well above conventional levels.
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 approach achieves efficient and selective urea synthesis from CO2 and NH3 under mild conditions, reducing environmental impact and operational costs, with improved CO2 fixation and urea production efficiencies.
Implementation Method 1
the addition of NH3 (I) in the aqueous solution of the catalysed reaction facilitates the fixation of CO2, 'fixation' being understood as the adsorption and, subsequent, transformation of CO2 into value-added chemical products
Implementation Method 2
utilizing a thermal stimulated polarisation process to enhance the catalyst's structural and electrical properties
Implementation Method 3
the synthesis of urea from carbon dioxide (CO2) and ammonia (NH3) in the presence of a permanently polarised catalyst
Data Source
Figure 1~1(f)
Figure 2~2b
Figure 3
AI summary
The present invention refers to a method for the synthesis of urea from carbon dioxide (CO2) and ammonia (NH3), wherein the method comprises contacting a gaseous stream of CO2 with an aqueous solution of NH3 in the presence of a permanently polarised catalyst at a temperature of 70-220°C and at a total gas pressure of 0.01-250 bar. In a further aspect, the invention refers to the use of a permanently polarised catalyst for: reducing CO2 present in a gaseous stream; reducing NH3 present in an aqueous solution; and/or producing urea, by implementing a method according to the invention.