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Molecular sieve used for denitration
Molecular sieve used for denitration 2023-05-12

SSZ-13 molecular sieve,with chabazite (CHA) topology, consists of AlO4 and SiO4 tetrahedron connected end to end by oxygen atoms, formed a ellipsoid cage (0.73 nm×1.2 nm)with eight membered ring structure and three-dimensional cross channel structure. The size of pore is 0.38 nm×0.38 nm and the specific surface area is up to 700 m2/g.

SSZ-13 shows excellent performance of NOX removal from automobile exhaust, MTO, and CO2 absorption and separation, owing to ordered pore structure, good hydrothermal stability, and more surface proton acidic center and exchangeable cations.

Main applications of SSZ-13 are as follows:

1, Application in NOX removal from automobile exhaust

NOX is one of the main pollutants in automobile exhaust, and makes great harm to environment and human health. To control the emission of NOX, three-way catalyst is used to remove CO、HC、NOX in gasoline cars. But different combustion mode from that of gasoline car, diesel car has higher oxygen content in exhaust, which makes the reduction of NOX extremely difficult in lean burn condition. So the catalytic reduction of NOX can’t be reacted using three-way catalysts in diesel cars. And development of new catalyst has attracted more and more worldwide attention.

Recent research has found that SSZ-13 is a suitable carrier and it shows good selective catalytic reduction ( SCR ) activity to NOX when loaded kinds of metal irons. So SSZ-13 has broad application prospect and huge development potential.

2, Application in methanol to olefins (MTO)

Mircopore molecular sieve with chabazite (CHA) topology has good selectivity to light olefins. And the geometric configuration plays a decisive role. The size of SSZ-13 cage hole decides the kinds of intermediate product. The size of SSZ-13 pores can exactly meet the requirement to produce the intermediate multi methyl benzene which is needed to produce light olefins. Therefore, SSZ-13 shows high selectivity to light olefins.

3, Application in gas separation

There is not only zeolitic channels, but also non-zeolitic channels with larger pore size than that of molecular sieve(3.8 Å)in SSZ-13 zeolitic membrane. SSZ-13 has a good capability to separate small molecular in gas phase due to the ability to separate CO2/CH4、H2/CH4、CO2/N2 and H2/n-C4H10. According to the result from R&D center of Dalian Haixin Chemical, the reasons why SSZ-13 has excellent separation capability are:

① The diffusion of the molecular is restricted by micropores.

② The zeolitic channel window is suitable to adsorb CO2, and the eight membered ring window can’t be occupied by exchangeable irons during the iron exchange process.

③ Static electricity of different gases has different adsorption site.