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what is urea

What is Urea?

Urea, also known as carbamide. It is a white crystal containing carbon, nitrogen, oxygen, and hydrogen. One of the simplest organic compounds, it is the main nitrogenous end product of the metabolic breakdown of proteins in mammals and some fish.

Urea, being a neutral fertilizer, is well-suited for a wide range of soils and plants. It is easy to store and use and has a small, destructive effect on the soil. It is a chemical nitrogen fertilizer used in large quantities and is also the nitrogen fertilizer with the highest nitrogen content. Under specific conditions, the industry utilizes ammonia and carbon dioxide to produce urea through synthesis.

Urea Chemical Formula: NH2CONH2/ CH4N2O

Urea Cas No: 57-13-6

Urea Molecular Wt: 60.056 g/mol

Urea Melting Point: 132.7 ℃

Urea Boiling Point: 196.6°C/Standard atmospheric pressure

Urea Density: 1.335 g/cm³

Solubility Of Urea In Water: 1080 g/L (20℃)

Urea Flash Point: 72.7 ℃

urea structure

Urea physical character

Urea is readily soluble in water, dissolving 105 grams in 100 millilitres of water at 20 degrees Celsius, with a neutral reaction in an aqueous solution.

There are two kinds of urea products. Crystalline urea is a white acicular or prismatic crystal, hygroscopic, hygroscopic agglomeration, and hygroscopicity 12 times faster than granular urea. In granular urea for particle size 1 ~ 2 mm translucent particles, the appearance of smooth hygroscopicity has improved significantly. 20 ℃ when the critical hygroscopicity point for the relative humidity is 80%, but 30 ℃, the critical hygroscopicity point is down to 72.5%, so the urea should be avoided in the summer humid climate open storage.

In the production of urea, the hygroscopicity of the urea is significantly reduced by adding hydrophobic substances such as paraffin.

urea chemical properties

Urea can interact with acids to form salts. It can undergo condensation reactions at high temperatures to produce diurea, triurea and cyanuric acid. Heated to 160 ℃ decomposition, the production of ammonia gas simultaneously into isocyanic acid. It is named urea because it is contained in human urine. Urea contains nitrogen (N) 46%, the highest nitrogen content in solid nitrogen fertilizers.

Urea in the acid, alkali, and enzyme action (the acid and alkali need to be heated) can be hydrolyzed to generate ammonia and carbon dioxide.

It is unstable to heat and will be deaminated into diurea when heated to 150~160℃. The reaction between copper sulphate and diurea is purple, which can be used to identify urea.

Acetyl urea and diacetyl urea can be generated by interaction with acetyl chloride or acetic anhydride.
It reacts with diethyl malonate under the action of sodium ethanol to form malonylurea (also called barbituric acid because of its particular acidity).

In the presence of alkaline catalysts like ammonia, it has the ability to react with formaldehyde and undergo condensation to form urea-formaldehyde resin.It reacts with hydrazine hydrate to form aminourea.

Urea History

Urea was discovered by Hilaire Rouelle in 1773 and was first synthesized artificially in 1828 by the German chemist Friedrich Wille using the inorganic substance ammonium cyanate (NH4CNO, an inorganic compound that can be produced by the reaction of ammonium chloride and silver cyanate) with ammonium sulphate. Initially, he intended to synthesize ammonium cyanate, but instead, he obtained urea.

The synthesis of urea inaugurated the artificial synthesis of organic matter. This proved the vitalism theory wrong and opened up organic chemistry (The vitalism theory holds that inorganic matter is fundamentally different from organic matter, so that inorganic matter cannot be turned into organic matter and that organic compounds can only be produced by the cells of living things under the action of a special force, the vital force, and that artificial synthesis is not possible. Mammals, amphibians, and some fish contain urea in their urine; birds and reptiles emit uric acid because their nitrogen metabolism processes use less water).

Hilaire Rouelle

urea preparation method

Method I
Synthesize ammonium carbamate with carbon dioxide and ammonia under high temperature and high pressure. After decomposition, absorption, and transformation, crystallize, separate, and dry.

Method II
The preparation method is to mix purified ammonia and carbon dioxide into the synthesis tower according to the molar ratio of 2.8-4.5, the pressure in the tower is 13.8-24.6 MPa, the temperature is 180-200 ℃, and the residence time of the reaction material is 25-40 min, to obtain the urea solution containing excess ammonia and ammonium carbamate, and then reduce the temperature by decompression and the urea solution after separating ammonia.Ammonium carbamate is evaporated to 99.5% or more and then granulated in the granulation tower to get the finished urea product.

Method III
Urea represents the ultimate product of protein metabolism in mammals. In 1922, Germany industrialized the production of urea synthesized from ammonia and carbon dioxide. Ammonia reacts with carbon dioxide to form amine carbamate, which is dehydrated to form urea.

Industrial Production Method
Production method: industrial use of liquid ammonia and carbon dioxide as raw materials, in high temperature and high-pressure conditions, direct synthesis of urea; the chemical reaction is as follows:
2NH3 + CO2 → NH2COONH4 → CO(NH2)2 + H2O

Ammonia Synthesis Converter

Urea Prilling Tower

Urea Use

urea medical use

Specific agents containing urea in dermatology enhance the skin’s moisture content. Closure dressings used for non-surgically removed nails contain 40% urea.

The carbon-14-breath test, which detects H. pylori, uses urea containing carbon 14 or carbon 13 markers. H. pylori’s urease enzyme uses urea to make ammonia and raise the stomach’s pH. The same principle can be used to test similar bacteria living in animal stomachs

urea use in agriculture

Urea is a highly concentrated nitrogen fertilizer. It is a neutral, quick-acting fertilizer that can also be used to produce a variety of compound fertilizers. It does not leave any harmful substances in the soil and has no adverse effects when applied for a long time.

It can be used as feed for ruminants in animal husbandry. However, too high a temperature in granulation will produce a small amount of urea, also known as biuret, which has an inhibitory effect on crops.

Urea can promote cell division and growth so that the branches and leaves grow luxuriantly. Here are some of its specific applications:

Regulating flower size
Flower and fruit thinning
Rice seed production
Pest control
Urea and iron fertilizer
Feed additives

Please read this article for specific applications of urea in agriculture CLICK THIS

urea for industrial use

It can be used in large quantities as raw material for the production of melamine, urea-formaldehyde resin, hydrazine hydrate, tetracycline, phenobarbital, caffeine, reduced brown BR, phthalocyanine blue B, phthalocyanine blue Bx, monosodium glutamate and many other products.
For steel, stainless steel chemical polishing has a brightening effect, is used as a corrosion inhibitor in metal pickling, and is also used in preparing palladium activation solution.
The industry is also used as a raw material for the manufacture of urea-formaldehyde resin, polyurethane, melamine-formaldehyde resin, and urea heated to 200 ° C to generate a solid state of trichloroacetic acid (i.e., cyanuric acid). A selective reducing agent, consisting of 32.5% high-purity urea and 67.5% deionized water, is used for denitrification of combustion exhaust gases and automotive urea.
Selective catalytic reduction (SCR) exhaust after treatment is a technology that carries out a selective catalytic reduction reaction with nitrogen oxides (NOx) in automobile exhaust through ammonia produced by the pyrolysis reaction of urea in the combustion exhaust. It is a key and mainstream technology to reduce NOx, a harmful substance in the combustion exhaust of combustion boilers, diesel engines, etc. Automotive grade urea is called AdBlue in Europe and DEF (Diesel Exhaust Fluid) in the United States.
Urea for cosmetics. Urea is a great moisturizing ingredient found in the skin’s stratum corneum and is the main component of the skin’s natural moisturizing factor, NMF. For the skin, urea moisturises and softens the cuticle, preventing the cuticle from clogging the pores, thus improving the problem of acne. It is a moisturizing ingredient in masks, lotions, creams, hand creams, and other products. Addition ratio is 3-5%.

urea in laboratory

Urea is very effective at denaturing proteins and is particularly effective at destroying non-covalently bonded proteins. This characteristic can increase the solubility of specific proteins at concentrations of up to 10 moles/volume. Urea can also be used to make urea nitrate.

urea storage

If urea is not stored correctly, it can easily absorb moisture and caking, affecting its original quality. Farmers incur certain economic losses, requiring customers to store urea correctly. When using urea, bags must be kept intact before use; the transportation process should be gently held, rain, and stored in a dry, well-ventilated temperature below 20 ℃.
If a large number of storage, the following should be padded up with wooden cubes about 20 centimetres; the upper part and the roof should be left with more than 50 centimetres of clearance to facilitate the ventilation of moisture, stacks, and stacks should be left between the aisle. To enable inspection and ventilation. If you have already opened bags of urea, such as those that still need to be used up, be sure to seal the bags promptly to facilitate next year’s use.
Avoid contact with skin and eyes.

As China leading urea supplier, we have industrial urea (prilled urea&granular urea), automotive grade urea(Adblue/DEF Urea).

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what is urea