Liquid Urea vs. Prilled Urea

In the world of Automotive Urea (DEF/AdBlue), the quality of the final product largely depends on the purity of its raw materials, but also on the efficiency of the logistics chain behind it. In this article, we explore the fundamental differences between liquid urea and prilled urea, focusing on why liquid urea offers strategic advantages for both production and application.

In the Selective Catalytic Reduction (SCR) industry, the quality of Automotive Urea solution (DEF/AdBlue) is critical for system efficiency and for meeting environmental standards. To achieve this, selecting the right base raw material is essential for both producers and end users. At Noxguard, we’ll explain it to you clearly.

What Is the Liquid Urea Used by Noxguard?

Liquid urea is a concentrated urea solution in demineralized water, obtained directly from the synthesis process of ammonia and CO₂. It is collected before any solidification treatment, preserving urea in its liquid state with high purity.

Key Features:

Liquid form, ready for processing
Purity levels above 99.7% for industrial applications
Transported in isothermal tanks or specialized tankers
Minimal post-processing: no need for dissolving or solid removal

Liquid Urea Production Process Steps:

1. Chemical Synthesis

Reactants: Ammonia (NH₃) + Carbon dioxide (CO₂)
Process: Takes place in pressurized reactors (~140–200 bar) at high temperatures (170–200°C)
Reaction: NH₃ + CO₂ → NH₂COONH₄ → (heat) → CO(NH₂)₂ (urea) + H₂O

2. Evaporation and Concentration

The raw solution is concentrated by evaporation, removing part of the water to reach 50% urea concentration, creating liquid urea.
This liquid is clear, highly pure, and homogeneous, with low biuret content thanks to controlled temperatures.

3. Cooling and Storage

The liquid is slightly cooled and stored in isothermal tanks or sent directly for processing.
Shipped via tank trucks, rail tanks, or ISO containers — no solidification needed.

What Is Prilled Urea? (Typically from China, Russia, and the Middle East)

Source: iamporpla-Urea fertilizer-Freepik

Prilled urea is solid urea formed into small spheres, produced by cooling and atomizing liquid urea. It is the most common form used in agricultural applications.

Key Features:

Solid granules
Requires dissolving and filtration before being suitable for automotive use
May contain impurities, biuret, and dust, making it unsuitable for direct DEF/AdBlue production

Prilled Urea Production Process

Steps:

1. Base Liquid Urea Production (same as above)

The same liquid urea is produced as the base.

2. Prilling (Solidification Process)

The hot liquid is sprayed from the top of a 40–60 meter prilling tower.
As the droplets fall, they solidify by air cooling into small spheres (prills).
High temperatures or prolonged exposure can lead to increased biuret formation.

3. Storage and Transport

Prills are packed in bulk supersacks and shipped in vessels where they are highly exposed to:
Environmental contamination (dust, insects)
Humidity, salinity, rain
Cross-contamination from previous cargo
Why Is Liquid Automotive Urea Superior to Prilled Urea?

Conclusion: Why Choose Liquid Urea?

Although prilled urea has historically been more accessible for various sectors, liquid urea proves to be a more efficient, cleaner, and strategic option for producing high-quality Automotive Urea. At Noxguard, we are committed to processes that not only meet the highest purity standards, but also optimize logistics and minimize environmental impact.

For companies like Noxguard, committed to quality, operational efficiency, and sustainability, liquid urea is the clear choice. That’s why we proudly maintain our Zero Prill Policy and are certified under the "Zero Prill Quality Standard."

Zero Prill