Abstract
We show that functionalization of SSZ-13 (CHA) and Fe-beta (*BEA) with copper using a recently reported solid-state ion-exchange method, facilitated by NH 3 and nitrogen oxides (NO), is a viable route to prepare Cu-SSZ-13 and (Cu + Fe)-beta catalysts, starting from H-SSZ-13 and Fe-beta, respectively. The physicochemical properties of the prepared catalysts are characterized by XRD, UV-Vis-spectroscopy and STEM-EDS, confirming that copper originally present in the physical mixture of CuO and H-SSZ-13, and CuO and Fe-beta, is inserted into the micropores of SSZ-13 and Fe-beta, respectively. Activity measurements in gas-flow reactor show that the samples are active for NO reduction by NH 3 -SCR over a broad temperature range, i.e., 150–500 ∘ C. For the Cu-SSZ-13 catalysts, which have a copper loading range of 0.5–4 wt. %, the sample prepared from the physical mixture with a CuO/SSZ-13 ratio corresponding to 2 wt. % Cu is the most active catalyst for NH 3 -SCR under the present reaction conditions. Furthermore, the (Cu + Fe)-beta catalyst shows higher NH 3 -SCR activity over a broader temperature range and especially at low temperature as compared to the Fe-beta and Cu-beta counterparts. The results encourage further elaboration on sequential ion-exchange procedures for bimetallic functionalization of zeolites.
Highlights
Worldwide environmental regulations regarding emissions of nitrogen oxides (NOx ) from automotives are becoming more and more stringent
The objective of the present study is to investigate if functionalization of SSZ-13 and Fe-beta with copper using NH3 - and NO-facilitated solid-state ion-exchange ([NH3 +NO]-SSIE) is a viable route to prepare Cu-SSZ-13 and (Cu + Fe)-beta catalysts active for NH3 -Selective catalytic reduction (SCR), starting from H-SSZ-13 and
The CuO peak intensity is found to decrease for each sample after the [NH3 +NO]-SSIE, which is in accordance with the finding by Shwan et al that CuO is consumed while treating the samples with NO and NH3 [16]
Summary
Worldwide environmental regulations regarding emissions of nitrogen oxides (NOx ) from automotives are becoming more and more stringent. This poses a continuous need to improve existing technologies and develop new concepts that can meet prescribed and upcoming emission standards. In general Cu-zeolites show higher low-temperature (400 ◦ C) than. Amongst the different zeolite structures that have been proposed as NH3 -SCR catalysts, zeolites with CHA and *BEA framework topologies have received much attention thanks to high low-temperature activity and hydrothermal stability [2,3]
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