The commercial synthesis of urea involves the combination of ammonia and carbon dioxide at high pressure to form Ammonium Carbamate. This is a fast, exothermic reaction that goes to completion. The Ammonium Carbamate goes through dehydration by the application of heat to form urea and water. This is a slow, endothermic reaction that does not go to completion. The conversion, on a CO2 basis, is usually 50 - 80%.
Urea is available in solid pellet or liquid form.
Urea Pellets (Solid)
Urea is approximately 56% in terms of nitrogen content.
Urea can be converted to ammonia on-site.
The conversion may require more or less urea depending on the quantity of ammonia made per ton of urea (based on nitrogen content).
Advantages: Eliminates requirement for large storage systems and requires less handling for delivery and storage.
Disadvantages: Adds to system complexity because of the need for de-mineralized water and these systems typically have higher operating and maintenance costs.
Urea liquid is similar to Aqua Ammonia as it can be directly injected into system processes.
Advantages: It eliminates system complexity because there is no need to convert the urea to ammonia.
Disadvantages: It increases product cost due to the dilution factor and requires containment areas in the event of liquid releases.
Urea is used as a fertilizer because of its high nitrogen content and its ability to readily convert to ammonia in the soil. It is incorporated into many mixed fertilizers. It can be applied alone to soil or sprayed onto foliage.
Methylene-Urea fertilizers are created when urea is treated with formaldehyde. This process allows the nitrogen to release slowly, continuously and uniformly.
Urea is used as a significant part of livestock food to meet protein requirements.
Urea-formaldehyde resin is created when the two (2) components are heated in the presence of mild alkalies. They undergo a condensation reaction that combines them and forms a water-soluble polymer. This polymer is used to formulate adhesives and coating agents or when mixed with other substances to produce powders that can be molded into solid objects.
Urea is also used for the synthesis of barbiturates.
Urea reacts with alcohols to form urethanes.
Urea reacts with melonic esters to make barbituric acids.
Urea is also used in the Power Industry as a reducing agent. When it is appropriately mixed with combustion air, it reduces NOx emissions.
Odorless or slight ammonia odor
pH: 7.2 (10% water solution)
Decomposes at 270.8°F (132.7°C); decomposes into ammonia and carbon dioxide. If burned, emits small amounts of nitrogen oxides.
Solubility in water is 119g per 100g water at 77°F (25°C)
Specific gravity (H20=1):1.34 at 68°F (20°C); heavier than water
Molecular weight: 60.06
Storage & Handling
Urea is not listed as a Hazardous Material by the Department Of Transportation (DOT), Transport Canada (TC), International Maritime Organization (IMO) and the United Nations (UN).
Urea is most commonly stored in silos or warehouses.
A hopper or pneumatic truck is used in the transport and delivery of urea.