Charrad Rania, Solt Hanna E, Valyon József, Trif László, Ayari Faouzi, Mhamdi Mourad, Hancsók Jenő, Lónyi Ferenc
Laboratoire de Chimie des Matériaux et Catalyse, Faculté des Sciences de Tunis, Université Tunis El Manar, Tunis, Tunisie.
Institute of Materials and Environmental Chemistry, Research Centre for Natural Sciences, Magyar tudósok körútja 2, 1117, Budapest, Hungary.
ChemistryOpen. 2020 Nov 6;9(11):1123-1134. doi: 10.1002/open.202000239. eCollection 2020 Nov.
Co/SSZ-13 zeolites were prepared by heating the finely dispersed mixture of NH-SSZ-13 and different cobalt salts up to 550 °C. Investigations by thermogravimetry - differential scanning calorimetry - mass spectrometry provided new insight into details of the solid-state reaction. Formation of Co carrying hydrate melt or volatile species was shown to proceed from chloride, nitrate, or acetylacetonate Co precursor salts upon thermal treatment. This phase change allows the transport of the Co species into the zeolite pores. The reaction of the NH or H zeolite cations and the mobile Co precursors generates vapor or gas products, readily leaving the zeolite pores, and cobalt ions in lattice positions suggesting that solid-state ion-exchange is the prevailing process. The obtained catalysts are of good activity and N selectivity in the CH/NO-SCR reaction. The thermal treatment of acetate or formate salts give solid intermediates that are unable to get in contact and react with the cations in the zeolite micropores. These catalysts contain mainly Co-oxide clusters located on the outer surface of the zeolite crystallites and have poor catalytic performance.
通过将NH-SSZ-13与不同钴盐的精细分散混合物加热至550°C制备了Co/SSZ-13沸石。热重分析-差示扫描量热法-质谱研究为固态反应的细节提供了新的见解。结果表明，在热处理时，携带水合物熔体或挥发性物质的钴的形成源于氯化物、硝酸盐或乙酰丙酮钴前体盐。这种相变使得钴物种能够传输到沸石孔中。NH或H沸石阳离子与可移动的钴前体的反应产生蒸汽或气体产物，它们很容易离开沸石孔，而钴离子则处于晶格位置，这表明固态离子交换是主要过程。所获得的催化剂在CH/NO-SCR反应中具有良好的活性和N选择性。醋酸盐或甲酸盐的热处理产生的固体中间体无法与沸石微孔中的阳离子接触并发生反应。这些催化剂主要包含位于沸石微晶外表面的氧化钴簇，催化性能较差。
