Solvent free method of producing calcium and magnesium salt - urea crystalline compounds

IDF No.: LU-050317-01

Lead Inventor: Jonas Baltrusaitis, PhD Faculty Website

Department: Chemical & Biomolecular Engineering

Patent Status: US/Europe/China Filings


This invention describes a process of preparing calcium and magnesium salt - urea compounds using a solution free route.  Urea is a large volume nitrogen containing fertilizer but suffers from the propensity to hydrolyze in soil thus resulting in nitrogen losses to environment.  Encapsulating urea in a crystalline compound together with inorganic acids, such as H3PO4 and H2SO4 has been shown to significantly decrease urea losses to the environment.  Reports have shown that a molecular adduct of urea and phosphoric or nitric acid result in only a 0.7% nitrogen loss as ammonia as opposed to up to 61.1% of soil treated with urea only, suggesting major improvements in sustainable management of the global nitrogen cycle. Additionally, urea molecular adducts with inorganic Mg and Ca salts also contain other primary and secondary nutrients, such as P, Ca, Mg and S, necessary for a balanced nitrogen uptake.

Common ways of obtaining these crystalline Ca and Mg salt – urea adduct materials is through precipitation from saturated aqueous solutions. Use of aqueous solutions for the synthesis of calcium and magnesium salt-urea adduct crystals is a major drawback since it involves increased costs needed to transport solutions, additional crystallization equipment and liquid byproducts.

On the other hand, Mechanosynthesis is a dry preparation method that has already been applied in fertilizer engineering, but very few compounds made were well defined crystalline materials, such as KMgPO4 and NH4MgPO4 and layered double hydroxides (LDH), Mg-Al-NO3 (Mg:Al=3:1). In this invention we claim a new dry mechanochemical synthesis method of URCASU (CaSO4*4Urea), URECAP (Ca(H2PO4)2*4Urea), TURCAN (Ca(NO3)2*4Urea), SAVQAH (MgSO4*6Urea*0.5H2O), BORTAD (Mg(H2PO4)2*4Urea), and GEMDAF (Mg(NO3)2*4Urea*2H2O).

The invention also claims that variations of these structures with different content of crystalline urea and H2O are also possible using the mechanosynthesis method proposed. One embodiment of this method entails loading total 200 mg of CaSO4*2H2O and urea mixture in 1:4 molar ratio into 15 mL stainless steel jar together with 1 stainless steel ball and shaking it for 5 min at 26 Hz.  The resulting powder analyzed using powder XRD shows 100% conversion of the parent compounds into URCASU.

For more information please contact:


Director, Office of Technology Transfer

Lehigh University

354 Whitaker Lab

5 East Packer Street

Bethlehem, PA 18015-3181


Office: (610) 758-5841

Fax: (610) 758-5888

For Information, Contact:
Rick Smith
Lehigh University
Jonas Baltrusaitis
Kenneth Honer