Hierarchical Fe-ZSM-5 with nano-single-unit-cell for removal of nitrogen oxides

Recent Progress in the Application of Transition‐Metal Containing MFI topologies for NH3‐SCR‐DeNOx and NH3 oxidation

“…Typically these methods can be divided into either a "bottom-up" approach, requiring the adjustment of the hydrothermal synthesis protocol, e. g., hard templating and soft templating, "top-down" methods, involving post-synthetic modifications of conventional zeolite crystals, e. g., demetallation, delamination and assembly procedures, or "mixed" techniques approaches have been applied, which are summarized in a number of publications. [109][110][111][112][113][114][115][116][117][118][119][120][121] Among these methods, the "top-down" method of exposing the synthesized zeolite to an alkali/acid solution treatment (breaking the SiÀ OÀ Al and SiÀ OÀ Si bonds) is considered the most viable for large-scale industrial applications. [122][123][124] Typically, this is performed under fixed treatment conditions, i. e., optimized concentration, temperature and time of treatments, type of agent/presence of poredirecting agents (PDAs), stirring speed, etc.…”

“…For purposes of the preparation of micro‐/mesoporous, also called hierarchical (characterized by interconnected pore systems) zeolites or zeolites with inter‐/intracrystalline mesopores in the literature, or even macroporous zeolites different approaches have been applied. Typically these methods can be divided into either a “bottom‐up” approach, requiring the adjustment of the hydrothermal synthesis protocol, e. g., hard templating and soft templating, “top‐down” methods, involving post‐synthetic modifications of conventional zeolite crystals, e. g., demetallation, delamination and assembly procedures, or “mixed” techniques approaches have been applied, which are summarized in a number of publications [109–121] . Among these methods, the “top‐down” method of exposing the synthesized zeolite to an alkali/acid solution treatment (breaking the Si−O−Al and Si−O−Si bonds) is considered the most viable for large‐scale industrial applications [122–124] .…”

Experimental investigation to enhance the low‐temperature nitrogen oxide emission reduction in biodiesel exhaust using selective catalytic reduction with direct ammonia injection and manganese cerium zirconia catalyst

“…Vanadium‐based catalysts, which are being used to meet the Euro 1 V/V emission norms, exhibit the best conversion efficiency between 250 and 450°C but they are also highly susceptible to sulfur deactivation compared to other zeolite and other metal‐based catalysts 33 . Extensive research on copper and iron zeolites demonstrates that the Fe‐based zeolite catalysts exhibit their best conversion between 400 and 550°C in moderate to the high‐temperature range and poor conversion occurs below 300°C 34 whereas copper zeolite (CuZ) catalysts have a very good NO X conversion efficiency (around 95%) especially between 200 and 350°C 35,36 . Due to their superior low‐temperature performance, copper zeolite‐based catalysts are one of the preferred catalysts.…”