Urea Mixture Stabilization for Formaldehyde Scavenging
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Solution Overview
Problem
Existing urea solutions for formaldehyde scavenging in lignocellulose composite production are prone to precipitation, leading to instability and equipment corrosion, and do not effectively reduce formaldehyde emissions.
Innovation Solution
A urea mixture comprising urea, a urea-aldehyde resin, and a sugar, with specific molar ratios and concentrations, which is stable and effective as a formaldehyde scavenger and NOX reduction agent, reducing formaldehyde emissions and improving storage stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If high concentration urea solution is used as formaldehyde scavenger, then formaldehyde emissions are reduced, but urea precipitates out of solution causing instability
Solution Approach 1:
The patent introduces an intermediary substance (e.g., ethanolamine or other amines) that mediates between urea and the aqueous solution. This intermediary allows high concentrations of urea to remain dissolved by forming soluble complexes, preventing precipitation while maintaining the formaldehyde scavenging capability. The intermediary acts as a bridge that resolves the contradiction between high urea concentration and solution stability.
Solution Approach 2:
The patent changes the chemical parameters of the solution by adding substances that alter the solubility characteristics. By adjusting pH, adding co-solvents, or introducing complexing agents, the solution parameters are modified to maintain urea in dissolved state at high concentrations, thereby preventing precipitation while preserving formaldehyde reduction effectiveness.
2Stability of the object's composition
If salts are added to inhibit urea precipitation, then solution stability is improved, but equipment corrosion and build-up occur
Solution Approach 1:
The patent replaces durable but harmful salt-based stabilizers with alternative substances that achieve the same stabilization function without the harmful side effects. The new stabilizing agents (such as organic amines or chelating agents) provide precipitation inhibition without causing corrosion or equipment build-up, effectively substituting the harmful stabilizing mechanism with a benign one.
Solution Approach 2:
The patent converts the potential harm of high urea concentration (precipitation) into a benefit by using alternative stabilizing mechanisms that do not cause corrosion. Instead of using salts that stabilize urea but harm equipment, the patent employs substances that stabilize urea through different chemical mechanisms (complexation, pH control) that are beneficial to both solution stability and equipment integrity.
3Strength
If conventional amino-formaldehyde resins are used, then lignocellulose composite strength is achieved, but formaldehyde is released during production and curing
Solution Approach 1:
The patent introduces a formaldehyde scavenger as an intermediary substance that intercepts formaldehyde released during resin curing. This scavenger (such as urea or other amines) acts as a mediator that captures formaldehyde molecules, preventing their release into the environment while allowing the resin curing process to proceed and achieve the desired composite strength.
Solution Approach 2:
The patent converts the harmful formaldehyde release into a beneficial process by having formaldehyde react with the scavenger substance. The formaldehyde that would otherwise be harmful is instead converted into harmless or beneficial compounds (such as methylene bridges in the resin structure or stable adducts with the scavenger), thereby eliminating emissions while maintaining or even improving composite properties.
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 urea mixture provides enhanced stability, reduced formaldehyde emissions, and effective NOX reduction, making it suitable for use in lignocellulose composite production and combustion effluent treatment.
Implementation Method 1
Urea is typically used in solution form... solutions with high concentrations of urea, e.g., 40% aqueous urea, are susceptible to having the urea precipitate out of solution
Implementation Method 2
Urea mixtures and methods for making and using same... The urea mixture can include urea, a urea-aldehyde resin, a liquid medium, and a sugar
Implementation Method 3
the method for reducing emissions of NOX can include contacting a combustion effluent with a urea mixture
Data Source
AI summary
Urea mixtures and methods for making and using same are provided. In at least one specific embodiment, the urea mixture can include urea, a urea-aldehyde resin, a liquid medium, and a sugar. The urea mixture can have an aldehyde to urea molar ratio of about 0.2:1 to about 0.7:1. The urea mixture can have a sugar concentration of about 2 wt % to about 8 wt %, based on the combined weight of the urea, the urea-aldehyde resin, the liquid medium, and the sugar.