@article{BraunGebhardMatysiketal., author = {Braun, Peter and Gebhard, J{\"u}rgen and Matysik, Frank-Michael and Rabl, Hans-Peter}, title = {Potential Technical Approaches for Improving Low-Temperature NOx Conversion of Exhaust Aftertreatment Systems}, series = {Chemie Ingenieur Technik}, volume = {90}, journal = {Chemie Ingenieur Technik}, number = {6}, publisher = {WILEY-VCH}, doi = {10.1002/cite.201700122}, pages = {762 -- 773}, abstract = {Lean-burn engines, such as diesel engines, are widely used in mobile and stationary applications. Operation of lean-burn engines leads to formation of distinct amounts of nitrogen oxides (NO and NO2). Efficient aftertreatment is mandatory to meet legal requirements, especially at low exhaust temperatures, as for the future a decline of the exhaust temperature level can be predicted due to improved engine efficiencies. Within this review, potential technical solutions to enhance the DeNO(x)-aftertreatment efficiency at low exhaust temperatures are presented.}, language = {en} } @article{BraunRablMatysik, author = {Braun, Peter and Rabl, Hans-Peter and Matysik, Frank-Michael}, title = {Investigations on the Liquid-Phase Decomposition of AdBlue Urea for the Selective Catalytic Reduction Process}, series = {Chemie Ingenieur Technik}, volume = {91}, journal = {Chemie Ingenieur Technik}, number = {7}, publisher = {Wiley}, doi = {10.1002/cite.201800055}, pages = {961 -- 968}, abstract = {Difficulties in decomposing AdBlue to ammonia limit the applicability of selective catalytic reduction systems at low exhaust temperatures. Investigations on the decomposition of AdBlue in the liquid phase under elevated pressure at temperatures up to 165 degrees C were carried out. Besides effects of inorganic catalysts, the impact of pH on urea decomposition was examined. After dissolution in aqueous phase, the compounds ZnO, WO3, and MoO3 were found to be effective in liquid-phase AdBlue decomposition. However, the efficiency was dropping significantly over few hours. Decomposition of AdBlue urea was also found to be favored for alkaline and acidic conditions.}, language = {en} } @article{BraunDurnerRabletal., author = {Braun, Peter and Durner, Bernhard and Rabl, Hans-Peter and Matysik, Frank-Michael}, title = {Investigations on the decomposition of AdBlue urea in the liquid phase at low temperatures by an electrochemically induced pH shift}, series = {Monatshefte f{\"u}r Chemie}, volume = {150}, journal = {Monatshefte f{\"u}r Chemie}, number = {9}, publisher = {Springer}, doi = {10.1007/s00706-019-02406-6}, pages = {1633 -- 1641}, abstract = {Ammonia-based selective catalytic reduction (SCR) systems are the most widely used technology for reduction of nitrogen oxide emissions from lean-burn engines such as diesel engines. However, at low exhaust temperatures, the SCR process is limited by difficulties in the decomposition of the ammonia precursor urea, which is carried on-board using an aqueous solution "AdBlue". In this study, the decomposition of AdBlue urea induced by electrical current and the resulting associated pH shifts were investigated in a divided cell configuration in the liquid phase. The decomposition was found to be favored in both electrochemical compartments, anodic and cathodic, at temperatures of 60-80 degrees C compared to a reference without electrochemical treatment. In addition to the determination of ammonia contents using an ammonia sensor, IC/HPLC analyses were carried out for each sample. Different side products such as biuret, nitrate, cyanuric acid, ammelide, and others were formed. In the anodic compartment, nitrate formation could be observed due to oxidation of ammonia at the electrode surface. [GRAPHICS] .}, language = {en} }