A Review of Urea Pyrolysis to Produce NH₃ Used for NO_x Removal

Abstract

Urea pyrolysis, from which the denitration reactant ammonia is produced, plays an important role in the urea-based NOx removal process. Research into urea pyrolysis is mostly focused on three parts: urea pyrolysis pathway, catalytic hydrolysis of HNCO, and catalytic pyrolysis of aqueous urea solution. In this paper, detailed overview on research progress of urea pyrolysis was conducted. From the review, it could be concluded that although much research has been carried out, concentration was mainly in analysis of urea pyrolysis products and exploration of catalysts used to improve ammonia yields. Little work has been done on mechanism study and development of a kinetic model with high accuracy, which are still in great need nowadays.

Pengaruh Temperatur Operasi Terhadap Penurunan Kadar Biuret Dalam Urea Prill dari Evaporator Tingkat II di PT. Pupuk Kaltim

“…Dalam simulasi dekomposisi urea menggunakan integrasi kinetik model, urea telah meleleh dan terdekomposisi pada suhu 133 o C menghasilkan biuret [17]. Biuret mulai terdekomposisi pada suhu 190 o C -250 o C [18] [19].…”

The upgrading role of Al at T1/T2 sites in stabilizing Pd ions over Pd-beta passive NOx adsorbers under a reducing atmosphere

“…However, neither of these technologies can effectively remove NO x from cold-start emissions below approximately 200 °C. 8,9 Thus, NO x from the cold-start period will be directly released into the atmosphere, which has a large contribution to the total NO x emission during a drive cycle. Meanwhile, the use of advanced fuel-saving technologies enhances the efficiency of the engine and dramatically decreases the exhaust temperatures further.…”

Effect of different legume resource and technical parameters on urea hydrolysis

“…If wastewater without catalyst is to meet discharge standards, the reaction time must be extended to 210 minutes. The urea catalytic hydrolysis technology meets the demand of denitration reductant supply [5] ,energy consumption, urea utilization rate and other indicators were optimized. Urea hydrolysis can also prepare engineering cementing materials and free stable heavy metals.…”