Nonclassical from-shell-to-core growth of hierarchically organized SAPO-11 with enhanced catalytic performance in hydroisomerization of n-heptane. Issue 39 (1st April 2016)

• Record Type: Journal Article
• Authors: Jin, Dongliang; Liu, Zhiting; Zheng, Jingwei; Hua, Weiming; Chen, Jiao; Zhu, Kake; Zhou, Xinggui
• Is Part Of: RSC advances. Volume 6:Issue 39(2016)
• Page Start: 32523
• Page End: 32533
• Publication Date: 2016-04-01
• Subjects: Chemistry -- Periodicals; 540.5
• DOI: 10.1039/c6ra03039d
• Languages: English
• ISSNs: 2046-2069

Abstract

Abstract : A growth inhibitor combined tumbling crystallization to generate hierarchical SAPO-11 with enhanced isomer selectivity in hydroisomerization of n -heptane is reported. Abstract : Integrating hierarchical porosity over microporous zeotype materials is an effective way to promote their mass transfer properties and catalytic performances. A combined synthetic strategy using small molecular growth inhibitor 1, 2, 3-hexanetriol and tumbling crystallization condition to generate hierarchically organized SAPO-11 is herein presented. The addition of 1, 2, 3-hexanetriol in the synthetic gel of SAPO-11 under agitating conditions significantly altered its crystallization behaviour, resulting in the formation of a hierarchically organized architecture. An underlying nonclassical from-shell-to-core crystallization has been disclosed by time-dependent observation of the formation process. The hierarchically self-organized structure has been characterized by a suite of characterization techniques, such as XRD, N2 physisorption, SEM, TEM, mercury intrusion measurements, 27 Al, 29 Si, 31 P MAS NMR and pyridine adsorption IR (Py-IR). The structure featuring barrel-shaped architecture is comprised of aligned 300–400 nm primary building blocks with voids in between, constructing an auxiliary macro-/meso-pore system open to external surfaces. The catalytic performance of Pt supported on hierarchical SAPO-11 in n -heptane hydroisomerization has been assessed, showing that both catalytic activity and isomer yield have been increased with respect to a conventional sample. As the acidity for the hierarchical SAPO-11 is comparable to the conventional sample, the enhancement in catalytic performance is attributed to the small primary crystal size and macro-/meso-pore-connectivity, that are important for mass transfer.