One-Pot Three-Dimensional Printing Robust Self-Supporting MnO _x /Cu-SSZ-13 Zeolite Monolithic Catalysts for NH ₃ -SCR

Abstract

Honeycomb cordierite coated with Cu-SSZ-13 zeolite is widely used in the selective catalytic reduction of NO x with NH 3 (NH 3 -SCR) to reduce pollutants from vehicle emission. However, the conventional honeycomb catalysts fabricated via coating technique are limited by low zeolite loadings, easy loss of the deposited zeolites, and complicated preparation process. Herein, a facile 3D printing strategy is developed to one-step construct MnO x /Cu-SSZ-13 monolithic catalysts with excellent catalytic performance for NH 3 -SCR. Iron-containing halloysite nanotubes (Fe-HNTs) are introduced as printing ink additives to ensure the mechanical stability and modulate the NH 3 -SCR performance of the monolithic catalysts at high temperature. In-situ incorporating Mn into the Cu-SSZ-13 zeolite monoliths during 3D printing process boosts the mechanical strength of the monolithic structures from 2.54 MPa to 4.33 MPa as well as broadens the temperature window (165-550 o C) of the catalysts for NH 3 -SCR with NO x conversion of above 80%. Such robust multi-component-integrated 3D-

Improving the hydrothermal stability of Al-rich Cu-SSZ-13 zeolite via Pr-ion modification

“…The band observed at 210 nm is assigned to the charge transfer between the framework oxygen and Cu 2+ ions, while the band in the range of 600-800 nm arises from the electron d-d transitions of Cu 2+ ions in octahedral Cu species. [38][39][40] Aer hydrothermal aging, a new peak at 250 nm related to CuO x appears in the spectra of aged zeolites. Note that CuPr 1.2 -SSZ-13-HTA exhibits a higher intensity difference between the peak at 210 nm and the peak at 250 nm compared to Cu-SSZ-13-HTA.…”

Cu-OFF/ERI Zeolite: Intergrowth Structure Synergistically Boosting Selective Catalytic Reduction of NOx with NH3

“…Nitrogen oxide (NO x ) emissions, mainly originated from diesel engines, have caused a wide range of environmental concerns. 1,2 Selective catalytic reduction with ammonia (NH 3 −SCR) has been widely recognized as the dominant technology to remove NO x from diesel vehicles to meet the increasingly stringent emission standard. 3,4 Besides catalytic activity, excellent hydrothermal stability is also required for SCR catalysts because high temperature and humid conditions are frequently generated during the regeneration of the upstream diesel particulate filter.…”

“…Nitrogen oxide (NO x ) emissions, mainly originated from diesel engines, have caused a wide range of environmental concerns. , Selective catalytic reduction with ammonia (NH 3 –SCR) has been widely recognized as the dominant technology to remove NO x from diesel vehicles to meet the increasingly stringent emission standard. , Besides catalytic activity, excellent hydrothermal stability is also required for SCR catalysts because high temperature and humid conditions are frequently generated during the regeneration of the upstream diesel particulate filter . Additionally, remarkable low-temperature activity is also crucial for SCR catalysts, especially after hydrothermal treatment, as up to 40–90% of NO x is emitted during the cold start process, , and the exhaust temperature would be further decreased with the development of internal combustion engines. , …”

Coaxial 3D Printing of Zeolite‐Based Core–Shell Monolithic Cu‐SSZ‐13@SiO2 Catalysts for Diesel Exhaust Treatment

“…[ 20,21 ] Recently, a number of porous monolithic materials based on porous carbons, metal–organic frameworks (MOFs), and zeolites have been fabricated via 3D printing and used for biomedical engineering, adsorption/separation, and catalysis. [ 22 − 26 ] Notably, 3D‐printed zeolite catalysts with designable core–shell structures were constructed by secondary growth, as reported for ZSM‐5@SAPO‐34 [ 27,28 ] and HY@SAPO‐34. [ 29 ] However, the strong alkaline solution used to grow the secondary zeolite shell leads to the dissolution of the core materials and even generates large amounts of byproducts and waste solutions, resulting in the low cost‐effectiveness and poor versatility of this strategy.…”