Mechanistic studies and design of highly active cuprate catalysts for the direct decomposition and selective reduction of nitric oxide and hydrocarbons to nitrogen for abatement of stack emissions

摘要

A flow trough type catalytic reactor system was adequately modified for NO related catalytic and adsorption measurements, including the on-line connection of a digital chemiluminescent NO-NO(sub x) analyzer to the reactor outlet system. Moreover, we have largely completed the installation of an FTIR coupled catalytic system containing a HTEC cell for high temperature DRIFT studies. Three different barium cuprate samples, Ba(sub 2)CuO(sub 3), BaCuO(sub 2), and Ba(sub 2)Cu(sub 3)O(sub 5) were synthesized and characterized by powder XRD for catalytic tests. Prior to catalytic studies over these cuprates, a new, liquid indium based supported molten metal catalyst (In-SMMC) was tested in the reduction of NO by various reductants. In the presence of excess O(sub 2) and H(sub 2)O, the In-SMMC proved to be more active for the selective catalytic reduction (SCR) of NO to N(sub 2) by ethanol than most other catalysts. Using C(sub 1)-C(sub 3) alcohols as reductants, self sustained periodic oscillations observed in the NO(sub x) concentrations of reactor effluents indicated the first time that radical intermediates can be involved in the SCR of NO by alcohols. Further, In-SMMC is the only effective and water tolerant SCR catalyst reported thus far which contains SiO(sub 2) support. Thus, this novel catalyst opens up a promising new alternative for developing an effective and durable catalyst for NO(sub x) abatement in stack emission.