Glycol Ether Solvent System for NBPT Stability
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Solution Overview
Problem
Current urease inhibitors like N-(n-butyl)thiophosphoric triamide (NBPT) face challenges with decomposition due to moisture and temperature instability, making direct application on urea difficult, especially at low temperatures, and existing solvent systems are not effective in maintaining high NBPT concentration and stability.
Innovation Solution
A composition containing N-alkyl thiophosphoric triamide with a solvent system of glycol ethers, such as diethyleneglycol monomethylether, and auxiliary substances like polyvinylpyrrolidone, which improves stability and prevents crystallization at low temperatures, ensuring high NBPT concentration and low water content.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If NBPT is dissolved in conventional solvent systems (aliphatic diols/triols), then high NBPT concentration (up to 50 wt.%) is achieved, but the solution solidifies or crystallizes at temperatures below 15°C
Solution Approach 1:
The patent changes the chemical composition parameters of the solvent system by introducing glycol ethers with specific molecular structures (formula I and II) that have lower freezing points. This parameter change allows the solution to maintain liquid state at lower temperatures while preserving high NBPT concentration, directly resolving the contradiction between concentration and solidification temperature.
Solution Approach 2:
The patent creates a composite solvent system combining glycol ethers (primary solvent) with auxiliary substances like polyvinylpyrrolidone or N-methylpyrrolidone. This composite approach leverages the low-temperature fluidity of glycol ethers and the stabilizing properties of auxiliary substances to prevent crystallization, solving both the temperature and stability issues simultaneously.
2Quantity of substance
If conventional diols and triols are used as solvents, then NBPT solution can be prepared, but water content increases during storage due to hygroscopicity, causing NBPT decomposition
Solution Approach 1:
The patent selects glycol ethers that are commercially available in technical grade with inherently low water content (0.01-0.05 wt.%). By choosing solvents that start with minimal water content and have low hygroscopicity, the system minimizes water uptake during storage, thereby preventing NBPT hydrolysis and maintaining stability without requiring additional protective measures.
Solution Approach 2:
The glycol ether-based solvent system creates a relatively inert chemical environment that is less prone to absorbing moisture from the atmosphere compared to conventional diols and triols. This inert characteristic of the solvent system protects NBPT from water-induced decomposition during long-term storage.
3Temperature
If liquid amides (e.g., N-methylpyrrolidone) are added to shift solidification temperature to 0°C, then low-temperature fluidity is improved, but health risks increase due to carcinogenic and teratogenic properties
Solution Approach 1:
The patent extracts and eliminates the harmful liquid amide component from the solvent system. Instead of using N-methylpyrrolidone or similar toxic substances, the patent employs glycol ethers (diethyleneglycol monomethylether, dipropyleneglycol monomethylether, triethyleneglycol monomethylether, or diethyleneglycol monobutylether) that provide the same low-temperature fluidity benefit without the carcinogenic and teratogenic health risks, achieving the same technical effect through a safer chemical pathway.
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 solvent system maintains NBPT stability and prevents crystallization at very low temperatures, allowing for effective impregnation of urea fertilizers, reducing volatility and flammability, and ensuring long-term storage without significant degradation.
Implementation Method 1
high solubility and stability of NBPT in the solvent
Implementation Method 2
resistance of the NBPT solutions against the crystallization at a low temperature
Implementation Method 3
The instability of NBPT towards hydrolysis is well known... During a longer storage period, the presence of water causes the decomposition of N-(n-butyl) thiophosphoric triamide (NBPT) into non-effective substances
Data Source
Figure 1
AI summary
Object of the present invention are novel solvent systems for the preparation of N-alkyl thiophosphoric triamide solutions, containing one or more glycol ethers of the general formula (I), wherein R1 is hydrogen or methyl, R2 is selected from the group consisting of C1-C6 alkyl, C3-C6 isoalkyl, C4-C6 tertiary alkyl, n = 2-4, and optionally further auxiliary substances improving the stability and applicability properties of the solutions. Object of the invention are further compositions containing N-alkyl thiophosphoric triamide, containing at least one N-alkyl thiophosphoric triamide and the solvent system of the invention, and also the use of the composition containing N-alkyl thiophosphoric triamide.