Alkaline-modified ZSM-5 zeolite to control hydrocarbon cold-start emission

Recent advances in gasoline three-way catalyst formulation: A review

“…Kustov et al 48 examined the use of Li, Na, and K-modified ZSM-5 zeolite materials for toluene adsorption (Figure 8). They found that Li or Na doping (to 5 wt% and 2.5 wt%, respectively) provided the largest advantages for toluene storage, as well as high-temperature desorption (between 200°C and 400°C).…”

“…There are a large number of possible zeolite materials, and many have been used as HC trap materials, including Y zeolite, ZSM-5 (MFI), USY, BEA, mordenite, FAU, and FER with various SiO 2 –Al 2 O 3 ratios of 1 to 150. 48 Therefore, a comprehensive examination of zeolite properties, correlated to performance, is desired. Westermann and Azambre 50 looked into the effectiveness of six different zeolites for use in a HC trap: HY-15 and Hβ-12.5 (large pores), HZSM5-5.5 and 5A-2 (medium pores), HFER-10 (small pores with two-dimensional structure), and HMOR-10 (large pores but one-dimensional structure).…”

“…For instance, while higher molecular weight HCs (such as toluene) are taken up by zeolite materials to a high degree, lighter molecules such as propene are only lightly adsorbed and can desorb from the trap at temperatures far below light-off. 47 Kustov et al 48 examined the use of Li, Na, and Kmodified ZSM-5 zeolite materials for toluene adsorption ( Figure 8). They found that Li or Na doping (to 5 wt% and 2.5 wt%, respectively) provided the largest advantages for toluene storage, as well as hightemperature desorption (between 200°C and 400°C).…”

“…Temperature-programmed desorption of toluene from ZSM-5 zeolites. Reproduced with permission from Elsevier 48. Pt/Rh TWC and a Pd/ZSM-5 underfloor catalyst, NO x emissions during the initial cold-start period were reduced from 200 to 50 ppm.…”

Dynamic Adsorption/Desorption of NOx on MFI Zeolites: Effects of Relative Humidity and Si/Al Ratio

“…Wang et al [ 17 ] reported that the NO x adsorption capacity decreased for HGeW polyoxometalate after three regeneration cycles. Contrastingly, zeolites, as typical crystalline aluminosilicates with well-defined microporosities, have promising applications for the treatment of flue gas denitration benefiting from appealing features such as highly ordered aperture size, tunable hydrophilic-hydrophobic, and excellent thermal stability [ 18 ]. Recently, studies on NO x adsorption over zeolites have been reported under dry conditions.…”