Thermal and hydrothermal stability of La-modified ETS-10 and its cracking ability
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Catalysis Letters Vol. 99, Nos. 3–4, February 2005 (Ó 2005) DOI: 10.1007/s10562-005-2109-5
Thermal and hydrothermal stability of La-modified ETS-10 and its cracking ability Huifeng Li, Baojian Shen,* Xiaohua Wang and Shikong Shen State Key Laboratory of Heavy Oil Processing, the Key Laboratory of Catalysis of CNPC, and Faculty of Chemical Engineering, University of Petroleum, Changping, Beijing, and 102249 P.R. China
Received 3 October 2004; accepted 9 November 2004
The ETS-l0 molecular sieve was modified with lanthanum by ion-exchange method. The lanthanum modified ETS-10 shows best thermal and hydrothermal stability in comparison with the as-synthesized ETS-10 and ammonium-exchanged ETS-10. Moreover, the lanthanum modified ETS-10 has an increase in the conversion of n-hexadecane by more than 3%, compared with the ammonium-exchanged ETS-10. And the reasonable speculation was presented based on the detailed characterization of these samples by DSC, FT-IR, XRD, XRF and N2 physisorption. KEY WORDS: lanthanum; ion-exchange; ETS-10; thermal and hydrothermal stability; cracking ability.
1. Introduction The unique microporous titanosilicate molecular sieve, ETS-10, consisting of a 3D 12-ring structure, has received considerable attention since it was discovered by Engelhard in 1989 [1]. Moreover, ETS-10 was endowed with special exchange properties and potential catalytic performance for the charge-balancing cations (Naþ and Kþ ) on its extra-framework [2–5]. It is well known that, the lanthanum-modified Y zeolite exhibited superior performance in comparison with ammonium exchanged Y zeolite, such as better thermal and hydrothermal stability, stronger acidity [6,7]. To the best of our knowledge, however, the study on the lanthanum-modified ETS-10 was not seen in the open literature. The aim of our present work is to investigate the effects of lanthanum modification on the thermal and hydrothermal stability and catalytic cracking ability of ETS-10.
2. Experimental 2.1. Catalyst preparation ETS-10(designated ETS, for convenience) was synthesized using the hydrothermal method [8]. A series of lanthanum-modified ETS-10 (designated HLa1-ETS, HLa2-ETS, HLa3-ETS, respectively) were obtained by means of ion-exchanging of ETS-10 with different amount of lanthanum nitrate in the ammonium nitrate mixed solution, followed by filtering, washing with deionized water, drying at 393 K for 4 h. The *To whom correspondence should be addressed. E-mail: [email protected]
corresponding lanthanum contents of HLa1-ETS, HLa2-ETS and HLa3-ETS (calculated by La2 O3 ) are 3.04, 3.65 and 4.21 wt% respectively. And the ammonium-exchanged ETS-10 (designated H-Ets) as the reference sample was obtained using the same treatment. 2.2. Characterization 2.2.1. Differential scanning calorimetry The differential scanning calorimetry (DSC) of the samples were performed on a Netzsch STA 409 simultaneous thermal analysis apparatus. The samples were heated in a Pt-Rh crucible with a heating rate of 10 K/min in argon atmosphere. The flow rate of argon was 20 cm3 /m
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