Mesoporous Y zeolite with homogeneous aluminum distribution obtained by sequential desilication–dealumination and its performance in the catalytic cracking of cumene and 1,3,5-triisopropylbenzene

• Published in: Journal of catalysis Vol. 278; no. 2; pp. 266 - 275
• Main Authors: Qin, Zhengxing, Shen, Baojian, Gao, Xionghou, Lin, Feng, Wang, Baojie, Xu, Chunming
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier Inc 07.03.2011; Elsevier; Elsevier BV
• Subjects: aluminum; Aluminum silicates; Aluminum–silicon distribution; ammonium compounds; Ammonium hexafluorosilicate; Catalysis; Catalysts; catalytic activity; Catalytic cracking; Chemistry; Colloidal state and disperse state; cracking; crystal structure; Dealumination; Desilication; Exact sciences and technology; General and physical chemistry; Hydrocarbon leakage & seepage; hydrocarbons; Ion-exchange; Mesopore; porosity; Porous materials; silicon; sodium hydroxide; Surface physical chemistry; Theory of reactions, general kinetics. Catalysis. Nomenclature, chemical documentation, computer chemistry; Y zeolite; zeolites; Zeolites: preparations and properties; Desilication; Dealumination; Aluminum–silicon distribution; Ammonium hexafluorosilicate; Y zeolite; Mesopore; Catalytic cracking; Conversion rate; Porous material; Molecular sieve; Sequential; Aluminum-silicon distribution; Cumene; Defect; Silicon; Deposition; Uniformity; Catalytic reaction; Deactivation; Hydrocarbon; Aluminium; Zeolite; Mesoporosity; Heterogeneous catalysis; Distribution; Benzenic compound; Transport; Catalyst
• ISSN: 0021-9517; 1090-2694
• DOI: 10.1016/j.jcat.2010.12.013

AHFS dealumination leads to severe non-uniform dealumination of zeolite framework and substantial surface silicon deposition. Sequential desilication and dealumination affords sample with mesopore formation and noteworthy improved aluminum–silicon distribution. [Display omitted] ► Mesoporous Y zeolite is prepared by sequential desilication and dealumination. ► Desilication facilitates intra-crystalline diffusion and induces mesopore formation. ► Aluminum–silicon distribution of the product is greatly improved. ► Activity of zeolite obtained by sequential desilication–dealumination is increased. The aluminum–silicon distribution and mesoporosity of Y zeolites prepared by sequential NaOH desilication and ammonium hexafluorosilicate (AHFS) dealumination are compared with that of Y samples prepared via AHFS dealumination only. AHFS treatment led to severe non-uniform dealumination and substantial surface silicon deposition. Y samples obtained by sequential desilication and dealumination had substantially better dealumination uniformity and aluminum–silicon distribution. The mesopore formation in these zeolites is discussed in detail. The desilication creates defects in the framework of the parent NaY zeolite. These defects improve the intra-crystalline transport and induce mesopore formation during dealumination. The desilication- plus dealumination-treated zeolites showed higher initial activity and lower deactivation tendency in the case of 1,3,5-triisopropylbenzene cracking, and higher conversion rate of cumene than those zeolites modified by AHFS treatment only. These catalytic data indicate that the former could be a viable catalyst in the catalytic cracking of heavy hydrocarbons.