Fluorinated alumina for benzene propylation: reaction scheme and heterogeneity of the acid surface

Moreno-Bravo, M.; Hernández-Luna, Martín; Alcaraz‐Cienfuegos, Jorge; Rosas-Aburto, A.

doi:10.1016/s0926-860x(03)00198-4

Cited by 5 publications

(2 citation statements)

References 10 publications

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“…Aluminum hydroxide fluorides (e.g., pyrochlore) are well-known compounds with high surface areas, particle sizes in the nanoscale range, and strong Lewis acid sites as well as weak and medium strong Brønsted sites . These properties make aluminum hydroxide fluorides valuable catalysts in, e.g., the synthesis of α-tocopherol (vitamin E), halogen exchange reactions, or Friedel−Crafts acylation . Such aluminum hydroxide fluorides can be synthesized by many ways, e.g., by precipitation from solutions of aluminum fluorosulfate by treatment with ammonia or thermal treatment of AlF 2 (O t Bu) .…”

Section: Introductionmentioning

confidence: 99%

Structure and Properties of Noncrystalline Aluminum Oxide-Hydroxide Fluorides

et al. 2010

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The thermal treatment of sol−gel derived aluminum hydroxide fluorides leads to new, X-ray amorphous, macroporous aluminum oxide-hydroxide fluorides. Followed by EA, DTA-TG, XPS, FT-IR, NH3-TPD, BET, XRD, and MAS NMR, it can be shown that the simplified composition of these compounds is “AlFO” and “AlF2O1/2”, respectively. These aluminum oxide-hydroxide fluorides exhibit a large number of acid centers. The local structure consists of AlF x Ocn-x units (cn, coordination numbers 6, 5, 4), and all sites are partially fluorinated. It can be shown that bridged and terminal F-sites are related to 5- and 6-fold coordinated Al sites.

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Section: Introductionmentioning

confidence: 99%

Structure and Properties of Noncrystalline Aluminum Oxide-Hydroxide Fluorides

et al. 2010

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“…2. Acidification of manufactured c-alumina with mineral acids as HF, HCl, H 3 PO 4 , and H 2 SO 4 or by acid bearing conjugated bases as NH 4 Cl and NH 4 F [8,[38][39][40]. 3.…”

Section: Introductionmentioning

confidence: 99%

A new route for the synthesis of self-acidified and granulated mesoporous alumina catalyst with superior Lewis acidity and its application in cumene conversion

et al. 2019

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Self-acidified and granulated mesoporous alumina (SAGMA) with dendritic-like microscopic shape was prepared by a new route that involves: (a) direct dehydration of AlCl 3 (in the presence of capping petroleum wax), and (b) oxi-dation of intermediary AlCl 3 -nanorods. The AlCl 3 solution dispersed in petro-leum wax (capping media) was firstly dehydrated at 100 °C under inert atmosphere for manufacturing anhydrous AlCl 3 -nanorods (length: 50-100 nm; diameter: 5-10 nm). In a second step, this support was oxidized into c-alumina at 300 °C, under air atmosphere. In the course of the manufacturing process, released chlorine was deposited at the surface of the nanorods (more specifically during the oxidation step). The binding of chlorine (5.35%, w/w at the surface) onto c-alumina was demonstrated by both electron dispersive X-ray analysis (SEM-EDX) and Fourier-transformed infrared spectroscopy. Specific surface area reached 230 m 2 g -1 ; the average pore size was 7.8 nm. Material charac-terization was completed by measuring the surface acidity through both tem-perature-programmed desorption and pyridine desorption. The morphology and the phase structure were investigated using scanning electron microscopy and X-ray diffraction analysis, respectively. SAGMA (c-alumina) can be described as a strong Lewis (1.713 mmol g -1 ; i.e., about 93% of total acid sites) and Brønsted acid catalyst supported on a mesoporous structure (self-granular size of 177-250 lm). Cumene conversion (through a dealkylation pathway) was tested on SAGMA: maximum catalytic activity reached 87% at 300 °C. The conversion is highly selective: the reaction produces benzene and only traces of ethylbenzene (mass fraction below 4% compared to benzene). Apart from this good catalytic efficiency, the material is characterized by its strong stability in terms of both catalytic activity (loss less than 2%, for optimum conditions) and surface acidity (loss less than 3%), even for long reaction times (i.e., 24 h) under severe conditions (i.e., T 300 °C). This new material, easily manufactured, is characterized by high efficiency and selectivity in cumene conversion into benzene, associated with high acidity and good stability

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