Novel synthesis strategy of SAPO-11 molecular sieve with superior performance for hydroisomerization of long-chain n-alkanes: Supergravity-cyclone assisted hydrothermal crystallization method

• Published in: Chemical engineering journal (Lausanne, Switzerland : 1996) Switzerland : 1996), 2023-09, Vol.472, p.144781, Article 144781
• Main Authors: Dai, Xiaojun, Cheng, Yan, Liu, Tingting, Wei, Qiang, Zhou, Yasong
• Format: Article
• Language: English
• Subjects: Hydroisomerization; Long-chain n-alkane; Non-noble metal supported catalyst; SAPO-11; Supergravity-cyclone assisted hydrothermal crystallization; Synthesis mechanism
• ISSN: 1385-8947; 1873-3212
• DOI: 10.1016/j.cej.2023.144781

[Display omitted] •High performance SAPO-11 was successfully synthesized by the supergravity-cyclone assisted hydrothermal crystallization method for the first time.•The effects of supergravity-cyclone technology on the properties of SAPO-11 molecular sieve and corresponding catalyst were investigated.•The mechanism of synthesizing high performance SAPO-11 molecular sieve by the supergravity-cyclone-assisted hydrothermal crystallization method was explored.•The hydroisomerization kinetics of n-hexadecane over NiWS/SAPO-11 catalyst was studied.•It is expected to provide a new strategy for the preparation of high performance SAPO-11 molecular sieve and hydroisomerization catalyst. In this work, we successfully synthesized high performance SAPO-11 molecular sieve via the novel supergravity-cyclone assisted hydrothermal crystallization method for the first time. The initial gel was subjected to cyclone treatment and supergravity shearing treatment to obtain the secondary molecular sieve precursor mixture with high viscosity and micro-bubble distribution. The effects of supergravity shear-cyclone operation on the physicochemical properties of SAPO-11 molecular sieve were investigated. The supergravity-cyclone treatment improved the textural properties and acidity of SAPO-11 molecular sieve. The effects of support properties on the properties of active phase of NiWS-support catalyst and its catalytic performance for hydroisomerization of n-hexadecane were further investigated. NiW/SAPO-11-B showed more active phase with hydroisomerization kinetics advantage and nearly doubled yield of i-hexadecane compared with conventional SAPO-11-based catalyst. The process and mechanism of synthesizing high performance SAPO-11 molecular sieve via the supergravity-cyclone technology were explored. It was found that the supergravity-cyclone assisted crystallization method shortened the crystallization time of SAPO-11 and improved the crystallization efficiency. In addition, the hydroisomerization kinetics of n-hexadecane on SAPO-11-based NiWS supported catalyst was studied. The structure–activity relationship between the structure of active phase and the formation of CUS was investigated, and the influence of support properties on the properties of NiWS active phase and their synergistic mechanism in the hydroisomerization of n-hexadecane were revealed. This is expected to provide a new strategy for the synthesis of high performance SAPO-11 molecular sieve and the preparation o