SSZ-33:  A Promising Material for Use as a Hydrocarbon Trap

Abstract

SSZ-33 is tested for possible application as a hydrocarbon trap by investigating the temperature-programmed desorption behavior of toluene (used as a probe molecule) and the results are compared to those obtained with zeolites β, Y, mordenite, and ZSM-5. SSZ-33 shows higher adsorption capacity than the other zeolites at the conditions used here, and as well as better hydrothermal stability than zeolite β, and is therefore identified as a promising candidate for use as a hydrocarbon trap in cold-start emission control.

Hydrocarbon Reformer Trap by Use of Transition Metal Oxide-Incorporated Beta Zeolites

“…5. The elution curve from H-beta was observed to be steep as reported previously [10]. Broad spectra were, on the other hand, obtained from Me-Al-beta samples.…”

“…Typically, the amount of adsorbed toluene was 0.11 cm 3 (STP) per gram of Fe-Al-beta. The amount of adsorbed HC on the trap materials relates closely to the micropore volume, decreasing with the decrease in volume caused by hydrothermal treatment for example [10,11]. The adsorption capacities of H-beta and Fe-Al-beta appear comparable, with the micropore volumes of those samples being 0.13 and 0.15 cm 3 per gram, respectively.…”

“…The longer the HC is held, better the HC trap system performs, because the TWC needs time to become activated by heat. Previously, we have found that SSZ-33, a new type of zeolite which is composed of an interconnected pore system of 10-and 12-membered rings, requires a longer time to diffuse throughout the crystal [10]. In this case, controlling the molecular traffic in the interior of the zeolite crystal might be a uniquely effective way to contain HCs.…”

One-Dimensional Molecular Sieves for Hydrocarbon Cold Start Emission Control

“…The ''light-off'' temperature is considered to be the temperature at which 50% of the emissions are converted. A variety of methods have been proposed to improve cold start emission control, including electrical heating of the catalyst or gas entering the catalyst [1] and trapping hydrocarbons until the catalyst reaches light-off temperature [2][3][4][5][6], whereupon the hydrocarbons are released for oxidation.…”

Synthesis and Toluene Adsorption/Desorption Property of Beta Zeolite Coated on Cordierite Honeycomb by an In Situ Crystallization Method

“…Among various zeolites, beta zeolite with wide-pore and high-silica microporous structure has attracted more attention due to good thermal and chemical stability, strong acid sites, hydrophobicity, and large pore size [7]. The investigations [3,8] found beta zeolite to be more promising for the adsorption of toluene and propene than other common zeolites such as mordenite, Y-type, and ZSM-5. Nowadays, zeolites are also emerging as versatile alternative adsorbents for volatile organic compounds (VOCs), which exhibit greater adsorption capacity than other materials such as alumina [9,10].…”