99-62-7Relevant academic research and scientific papers
Stabilizing Low-Silica Zeolites through Aluminum Sulfate Assisted Cannibalistic Dealumination
Shi, Zongbo,Ji, Peng,Zhu, Zhiguo,Jiang, Jin-Gang,Fu, Wenhua,Wu, Peng,Wang, Yimeng,He, Mingyuan
, p. 1891 - 1895 (2016)
A versatile dealumination strategy was proposed to stabilize low-silica zeolites through cannibalistic interaction between the host framework Al (FAL) and the guest aluminum salt. It is possible to capture selectively the FAL and Na ions in NaY zeolite by employing a special external Al source such as aluminum sulfate as the dealuminating agent. This unique postmodification reduces the FAL amount efficiently and converts the chemically reacted Al species into a γ-alumina support for the catalytically active component of zeolite, which avoids wasting Al sources. Possessing greatly enhanced hydrothermal stability, newly generated intracrystal mesopores, as well as an optimized distribution of FAL, the resultant dealuminated Y zeolite catalysts can be used practically in heavy oil cracking.
Hierarchical MFI Zeolites with a Single-Crystalline Sponge-Like Mesostructure
Zhang, Yunjuan,Luo, Peng,Xu, Hao,Han, Lu,Wu, Peng,Sun, Huai,Che, Shunai
supporting information, p. 19300 - 19308 (2018/11/27)
Single-crystalline sponge-like MFI mesoporous zeolites (SSMZs) have been synthesized by using bolaform surfactants with an axial chiral binaphthyl core in the hydrophobic tail and triquaternary ammonium head groups, as bifunctional organic structure-directing agents (OSDAs). By changing the length of alkyl chain between a triquaternary ammonium head group and a binaphthyl group from 4 to 10 carbons, SSMZs with high specific surface area (382–434 m2 g?1), abundant micropore-mesopore connectivity, and uniform mesopore diameter (4–10 nm) were obtained. OSDAs with an alkyl chain length of 11 and 12 carbons led to the formation of nanorod-constructed mesoporous MFI zeolites. A geometrical matching between the cylindrical arrangement of the binaphthyl groups and the zeolitic framework is speculated to be the key factor for the formation of mesoporous zeolites. The SSMZ zeolites, with abundant mesopores beneficial for the diffusion of reactants, exhibited significantly higher catalytic efficiencies than those of the conventional ZSM-5 with a microcrystal morphology (≈1.5 μm).
PROCESS FOR MAKING CUMENE BY ALKYLATION OF BENZENE USING AN ORGANOTEMPLATE-FREE ZEOLITE BETA
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Paragraph 0079, (2017/04/23)
A process for making cumene by the alkylation of benzene with propylene using a benzene alkylation catalyst that comprises an organotemplate-free zeolite beta having a silica-to-alumina molar ratio of less than 20 and synthesized without an organic structure directing agent (SDA).
Self-Assembly of Cetyltrimethylammonium Bromide and Lamellar Zeolite Precursor for the Preparation of Hierarchical MWW Zeolite
Xu, Le,Ji, Xinyi,Li, Shenhui,Zhou, Zhengyang,Du, Xin,Sun, Junliang,Deng, Feng,Che, Shunai,Wu, Peng
, p. 4512 - 4521 (2016/07/11)
Construction of hierarchical zeolite catalysts from lamellar zeolite precursor is challenging and promising for industrial catalysis. Although numerous efforts have been dedicated to control the organization of zeolite nanosheets by postsynthetic approaches or employing complex surfactants in hydrothermal synthesis, there is still no successful case that the hierarchical lamellar zeolite is hydrothermally synthesized by the self-assembly of the commercially available simple surfactant cetyltrimethylammonium bromide (CTAB) and inorganic zeolite precursor. In traditional syntheses, the self-assembly of simple surfactants and the growth of microporous framework are hardly compatible from both thermodynamic and kinetic viewpoints, preferring to cause phase separation. Herein, we approach for the first time the hydrothermal synthesis of a mesostructured multilamellar zeolite ECNU-7P, consisting of an alternative stacking of inorganic MWW zeolite nanosheets and organic CTAB layers with large interlayer spacing (25 ?), by a zeolite seed and CTAB-assisted dissolution-recrystallization route. Correlated 2D 1H-29Si solid-state NMR, X-ray, electron microscopy, and rotation electron diffraction analyses provide molecular-level insights into the guest-host interactions between organic surfactant and inorganic framework during the self-assembly and structure evolution process. Moreover, the calcined Al-ECNU-7 possessing a hierarchical mesostructure proves to serve as a highly active, selective, and stable solid acid catalyst for triisopropylbenzene cracking as well as acylation of anisole.
A comparative study on catalytic performance of modified nanocrystalline and microcrystalline zeolite X for synthesis of cumene by transalkylation of 1,4-diisopropylbenzene with benzene
Thakur,Barman
, p. 592 - 601 (2016/10/18)
Cumene is a commercially important product in the petrochemical industries. In isopropylation of benzene, 1,4-diisopropyl benzene (1,4-DIPB) is produced as low value by-product. This low value by-product DIPB is used to maximize the production of commercially important product cumene by transalkylation reaction. Reduction of crystal size in zeolite can increase surface area of the external surface and in this way bring about substantial changes in catalytic activity. Moreover modification with rare-earth metal enhances the acidity of zeolite. In this work, nanocrystalline and microcrystalline zeolite X were modified with cerium to study the combine effect of crystal size and ion modification of zeolite on selectivity of cumene in commercially important transalkylation reaction. Benzene and 1,4-diisopropylbenzene in a molar ratio of 1 to 12.5 were subjected to vapour-phase reaction in the temperature range of 498 to 593 K at atmospheric pressure with space time of 5.27–10.54 kg h/kmol. Nanosized crystalline zeolite gives much higher conversions of 1,4-DIPB than microcrystalline zeolite. Over cerium modified nanosized zeolite CeXN 81.85% conversion of 1,4-DIPB and 97% cumene selectivity were achieved. It was found that stability and activity of CeXN for cumene synthesis was much higher than that of CeXM zeolite. Kinetic constants for the reactions were estimated and the activation energies for various reactions over CeXM were determined. The activation enegy for transalkylation reaction was found to be 78.54 kJ/mol.
A mesoporous aluminosilicate prepared by simply coating fibrous γ-AlOOH on the external surface of SBA-15 for catalytic hydrocarbon cracking
Shi, Zongbo,Guan, Yejun,Wu, Peng,He, Mingyuan
, p. 40296 - 40303 (2016/05/24)
A binary SiO2/Al2O3 composite with fibrous γ-alumina coating on the external surface of SBA-15 has been synthesized by simply mixing SBA-15 with fibrous boehmite sol, followed by aging and calcination. The textural and aci
Synthesis and properties of MFI zeolites with microporous, mesoporous and macroporous hierarchical structures by a gel-casting technique
Wang, Ying,Wang, Runwei,Xu, Diou,Sun, Chuanyin,Ni, Ling,Fu, Weiwei,Zeng, Shangjing,Jiang, Shang,Zhang, Zongtao,Qiu, Shilun
supporting information, p. 4398 - 4405 (2016/06/09)
The comparatively small micropore dimensions of bulk ZSM-5 zeolites often limit both the adsorption and catalytic conversion of large organic molecules. Here, we report that ZSM-5 zeolites were prepared by a gel-casting technique with microporous, mesoporous and macroporous hierarchical structures. The as-prepared samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), nitrogen adsorption, temperature-programmed-desorption of ammonia (TPD-NH3) and Fourier transform infrared spectroscopy (FTIR) measurements. The hierarchical structured ZSM-5 zeolites were used to carry out catalytic cracking of 1,3,5-triisopropyl benzene and n-hexadecane. The results show that, compared with traditional ZSM-5, Beta or Al-MCM-41, this modified ZSM-5 displayed preferable catalytic activity and selectivity.
A solvent evaporation route towards fabrication of hierarchically porous ZSM-11 with highly accessible mesopores
Song, Wen,Liu, Zhiting,Liu, Liping,Skov, Anne Ladegaard,Song, Nan,Xiong, Guang,Zhu, Kake,Zhou, Xinggui
, p. 31195 - 31204 (2015/04/22)
A route to generate hierarchically porous zeolite ZSM-11 has been paved via solvent evaporation induced self-assembly assisted by hexadecyltrimethoxysilane to produce a preformed dry gel, followed by its subsequent transformation into zeolite via steam-assisted-crystallization. The crystallization in dry gel has been found to undergo an orientated attachment growth mechanism whereby hexadecyltrimethoxysilane directs the formation of auxiliary mesopores and inhibits the fusion of primary nucleates. Measurements such as XRD, SEM, TEM, N2-physisorption, and TEM for an inverse replica of Pt derived from hierarchical ZSM-11 have been conducted to characterize the textural properties of the material. Ammonia temperature-programmed-desorption (NH3-TPD) measurements and infrared spectra using probe molecules such as pyridine (Py-IR) and 2,4,6-collidine (Coll-IR) have been collected to investigate the acidic properties as well as the accessibility of the acid sites. The hierarchical ZSM-11 possesses more acid sites on the mesopore surfaces that are accessible towards large probe molecules such as 2,4,6-collidine. This improvement together with the enhanced pore-connectivity brings about an increase in 1,3,5-triisopropylbenzene cracking activity and benzene selectivity with respect to a conventional counterpart.
A facile approach for the preparation of tunable acid nano-catalysts with a hierarchically mesoporous structure
Choi, Youngbo,Yun, Yang Sik,Park, Hongseok,Park, Dae Sung,Yun, Danim,Yi, Jongheop
supporting information, p. 7652 - 7655 (2014/07/08)
A facile and efficient approach to prepare hierarchically and radially mesoporous nano-catalysts with tunable acidic properties has been successfully developed. The nanospheres show excellent catalytic performance for the acid catalysed reactions, i.e. cr
An active, general, and long-lived palladium catalyst for cross-couplings of deactivated (hetero)aryl chlorides and bromides with arylboronic acids
Hoshi, Takashi,Honma, Tomonobu,Mori, Ayako,Konishi, Maki,Sato, Tsutomu,Hagiwara, Hisahiro,Suzuki, Toshio
, p. 11513 - 11524 (2013/12/04)
An active, general, and long-lived palladium catalyst for Suzuki-Miyaura reactions of aryl and heteroaryl chlorides deactivated by steric hindrance, electron richness, and coordinating functional groups is reported. In reactions of arylbromide bearing two o-tert-butyl substituents, C(sp3)-H arylation of the tert-butyl group, rather than the Suzuki-Miyaura reaction, proceeded in excellent yield. The key to the success of the reactions was the development of biphenylene-substituted dicyclohexylruthenocenylphosphine (CyR-Phos) as a supporting ligand.
