Investigation of Urea Derived Deposits Composition in SCR Systems

2016-01-2327

10/17/2016

Event
SAE 2016 International Powertrains, Fuels & Lubricants Meeting
Authors Abstract
Content
Ideally, complete decomposition of urea should produce only two products in active Selective Catalytic Reduction (SCR) systems: ammonia and carbon dioxide. In reality, urea decomposition reaction is a two-step process that includes the formation of ammonia and isocyanic acid as intermediate products via thermolysis. Being highly reactive, isocyanic acid can initiate the formation of larger molecular weight compounds such as cyanuric acid (CYN), biuret (BIU), melamine (MEL), ammeline (AML), ammelide (AMD), and dicyandimide (DICY). These compounds can be responsible for the formation of deposits on the walls of the decomposition reactor in urea SCR systems. Composition of these deposits varies with temperature exposure, and under certain conditions can create oligomers that are difficult to remove from exhaust pipes. Deposits can affect efficiency of the urea decomposition, and if large enough, can inhibit the exhaust flow and negatively impact ammonia distribution on the SCR catalyst. This paper presents results of investigation of the deposits collected at various gas temperatures for quantification of urea and by-products of urea thermal decomposition and for their trace elements. Urea related compounds, including oligomers and elemental composition of deposits collected from a urea decomposition reactor under various exhaust conditions, are compared in the paper.
Meta TagsDetails
DOI
https://doi.org/10.4271/2016-01-2327
Pages
9
Citation
Eakle, S., Kroll, S., and Henry, C., "Investigation of Urea Derived Deposits Composition in SCR Systems," SAE Technical Paper 2016-01-2327, 2016, https://doi.org/10.4271/2016-01-2327.
Additional Details
Publisher
Published
Oct 17, 2016
Product Code
2016-01-2327
Content Type
Technical Paper
Language
English