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stabilities and its considerable resistance to deactivation caused by coking as well as its strong acidity [4]. Yoshimura et al. reported that La2O3/P/ZSM-5 zeolite (Si/Al = 100) exhibited a high naphtha catalytic cracking activity and a high yield of ca. 60% to light olefins (ethylene and propylene) at 923 K, and the propylene/ethylene ratio was approximately 0.7 [1]. Recently, we carried out catalytic cracking of n-hexane as a model reaction of naphtha cracking over H-ZSM-5 zeolites (Si/Al = 45) with different crystal sizes, and found that the catalytic stability could be improved by decreasing the crystal size [5]. However, the propylene selectivity at ca. 100% n-hexane conversion slightly decreased from ca. 32 to 26 C-% at 923 K. To improve the propylene selectivity in catalytic cracking, zeolite catalysts with other structures have been considered. Recently, dealuminated MCM-68 (MSE-type) zeolite (Si/Al = 51) with multidimensional 10-MR or 12-MR micropores has been reported to exhibit a high propylene selectivity of ca. 45–50 C-% and a high durability to coke formation during n-hexane cracking, regardless of the reaction temperature [6]. However, the n-hexane conversion was only changed from ca. 7%–75% by changing the reaction temperature from 723 to 873 K. Thus, the selectivity to propylene was uncertain when the n-hexane conversion approached 100%. More recently, we reported that dealuminated MCM-22 (MWW-type) zeolite (Si/Al = 62) with two dimensional sinusoidal 10-MR channels and 12-MR supercages exhibited a high propylene selectivity of ca. 40 C-% with a high n-hexane conversion of 95% and a high catalytic stability at 923 K [7]. Beta (*BEA-type) zeolite with three dimensional 12-MR channels has been an important catalyst in the petroleum industry, especially in the alkylation process of benzene for the production of ethylbenzene and cumene [8,9]. Additionally, Beta zeolite also shows an excellent catalytic performance in FCC processes [10]. It is well-known tha t the Brønsted acid sites (BAS) in the zeolite catalyst act as active sites in alkane cracking, and that Lewis acid sites (LAS) can enhance the cracking reaction [11,12]. However, a large amount of acid sites, especially the LAS, would accelerate the secondary reactions of propylene and butenes and the hydride transfer, leading to coke formation followed by deactivation [7]. Thus, dealumination of zeolite catalyst leads to an increase in propylene selectivity and the improvement of catalytic stability. It was reported that dealumination of Beta zeolite occurred very easily compared to other ones such as ZSM-5 and MCM-22, due to the presence of stacking defects [13]. The dealumination of Beta zeolite by different methods such as acid treatment, steaming treatment, and chemical treatments had already been studied in the literature [14–16]. However, the effect of dealumination of Beta zeolite on the catalytic performance of alkane cracking was seldom reported [6]. More recently, we have reported that the dealuminated organic structure-directing agent (OSDA) free Beta zeolite showed a better catalytic performance in n-hexane cracking [17]. 76PDF Image | Zeolite Catalysis
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