Adsorption as alternative process in the preliminary production of automotive additive

Abstract

Nitrogenous contaminants in diesel fraction are converted to NOx compounds in automotive combustion chamber, afterwards they are reduced to nitrogen by catalytic reduction/oxidation reactions in presence of ammonia derived from a 32.5 wt.% urea solution. This process is named selective catalytic reduction (SCR). In Brazil, the urea solution for SCR is ARLA 32 and must comply with the limit content of 0.3 wt.% of biuret. However, the commercial Brazilian urea solution has an average biuret content of 0.5 wt.%. Thus, it is necessary to adjust the biuret content in urea solution to be used as ARLA 32, and adsorption is a low energy option. The objective of this study was to evaluate commercial adsorbents for removing biuret from solution of commercial urea to adjust it to the specification of ARLA 32. Two activated coals and one ion exchange resin were tested in adsorption assays, with best performances of both coals.