Tertiary Butylation Of Phenol Research Articles

Novel ionic liquid-templated ordered mesoporous aluminosilicates: Synthesis, characterization and catalytic properties

Abstract Highly crystalline ordered mesoporous aluminosilicates with hexagonal AlIITM-41 and cubic AlIITM-48 pore symmetries with varying silicon-to-aluminium ratios were hydrothermally synthesized, for the first time, using long-chain ionic-liquid (IL) such as 1-hexadecyl-3-methylimidazolium chloride (HDMIC), as structure directing agent. The prepared materials were systematically characterized by various analytical, spectroscopic and imaging techniques, viz., XRD, BET, TEM and XRF. In addition, the extent of aluminium incorporation and the nature of acid sites were deduced from 27 Al MAS-NMR and NH 3 -TPD measurements. The structural and physico-chemical properties of both AlIITM-41 and AlIITM-48 were compared with analogous AlMCM-41 and AlMCM-48, respectively prepared using hexadecyltrimethylammonium bromide (CTAB). It was found that all the ionic liquid-templated materials, viz., AlIITM-41 and AlIITM-48, and exhibited large surface area, high crystallinity and thicker pore walls. The observed superior orderness of AlIITM-41 and AlIITM-48 could attribute to a well distributed positive charge and π-π stacking of aromatic imidazolium head group of ionic-liquid. In addition, it also assisted in the incorporation of all the aluminium species exclusively in the tetrahedral silicate framework even after the calcination as confirmed by 27 Al MAS NMR. AlIITM-41 and AlIITM-48 possess more medium and strong Bronsted acid sites due to their thicker walls, high crystallinity and presence of tetrahedral aluminium in the framework, due to which they exhibited higher catalytic activity towards tertiary butylation of phenol with a good Para tertiary butyl phenol selectivity compared to commonly used aluminosilicates, H-AlMCM-41 and H-AlMCM-48.

Designing ordered mesoporous aluminosilicates under acidic conditions via an intrinsic hydrolysis method.

Acid-mediated synthesis of ordered mesoporous aluminosilicates (OMAS) with medium-to-strong Brønsted acid sites and trivalent aluminium exclusively in a tetrahedral framework structure is realized by a newly devised intrinsic hydrolysis method. In this way, we have synthesized a series of well-ordered OMAS, e.g., H-AlSBA-15 and H-AlIITM-56, which are otherwise difficult to distinguish under acidic conditions owing to very different hydrolysis rates of both silicon and aluminium sources used for preparation as well as easy dissociation of thus formed Al-O-Si bonds. This novel intrinsic hydrolysis approach, however, relies mainly on similar hydrolysis rates of constituent inorganic species leading to efficient condensation. Thus, the innovative methodology using tetraethyl orthosilicate and aluminium citrate, respectively, as tetravalent silicon and trivalent aluminium as precursors facilitates the formation of high quality OMAS with a narrow pore size distribution, thicker walls, and trivalent aluminium in a tetrahedral framework structure with a high aluminium content, as evidenced by a battery of characterization techniques, viz., XRD, XRF, SEM, TEM and BET. The resulting materials, in turn, generate Brønsted acid sites in the aluminosilicate matrix, with the absence of the usually encountered Lewis acid sites, viz., extra-framework and/or non-framework species, as confirmed by both 27Al MAS-NMR and NH3-TPD studies. All the prepared catalysts exhibit excellent activity towards the tertiary butylation of phenol, and the high activity of the catalysts is attributed to the unique and exclusive presence of medium-to-strong acid sites in the OMAS matrix.

Shaping of mesoporous AISBA-15 as cylindrical nano reactor for tertiary butylation of phenol.

Mesoporous AISBA-15 with different n(Si)/n(Al) ratios (45, 136 and 215) in the powder (P) form were synthesized by hydrothermal technique. The powder materials were shaped into cylindrical extrudates (Ex) by compounding with additives such as bentonite (binder) and methylcellulose (plasticizer). The AISBA-15 materials were characterized by XRD, N2 adsorption, AAS, 27Al MAS-NMR and thermogravimetric analysis. The orderly growth of AISBA-15 is evidenced by its XRD patterns. The surface area and pore volume of AISBA-15 catalysts were around 950 m2/g and 1.3 cm3/g respectively. A decrease in surface area and pore volume were observed for AISBA-15 (Ex) materials in comparison to AISBA-15 (P) materials. This may be due to partial blocking of pore entry and surface area coverage of additives during the shaping of extrudates. Vapor phase alkylation of phenol with tert-butanol was carried out over AISBA-15 (P) and AISBA-15 (Ex) catalysts and the results revealed that both powder and extrudate samples showed similar activity for phenol conversion. The activity of AISBA-15 catalysts follows the order: AISBA-15 (45) > AISBA-15 (136) > AISBA-15 (215) for both powder and extrudate forms. The major products were 2-tert-butylphenol (2-TBP), 4-tert-butylphenol (4-TBP) and 2,4-di-tert-butylphenol (2,4-DTBP). The selectivity to para product is much higher than other products. The catalyst exhibited steady conversion, and deactivation by coke formation of the catalyst is much reduced in AISBA-15 materials.

Facile single step synthesis of an acid functionalized nano porous carbon composite as an efficient catalyst for tertiary butylation of phenol

A simple, one step, simultaneous carbonization and sulfonation of petroleum waste coal tar was conducted to produce acid functionalized nano porous carbon and applied for tertiary butylation of phenol.

Tertiary Butylation of Phenol Over Solid Acid Catalysts: An Overview on Recent Progress

Tertiary Butylation of Phenol Over Solid Acid Catalysts: An Overview on Recent Progress

Tertiary butylation of phenol over hexagonal p6 mm mesoporous aluminosilicates with enhanced acidity

Through a two-step crystallization procedure and using cetyltrimethylammonium bromide (CTAB) as template, hexagonal p6 mm mesoporous aluminosilicates (denoted as MB41) with n Si/ n Al ratios from 15 to 50 have been assembled from the preformed zeolite Beta precursors under alkaline conditions. MB41 materials were characterized by powder XRD, N 2 adsorption–desorption, 27Al-MAS NMR and pyridine adsorbed FT-IR spectroscopy techniques. Results obtained show that they are highly ordered hexagonal symmetry, and Al atoms are in tetrahedral coordination. Compared with classic Al-MCM-41, MB41 materials have stronger acidity, and also show significantly higher activities in the alkylation reaction of phenol with tert-butanol. At the reaction temperature of 145 °C, phenol conversion of 85.7% and 2,4-DTBP selectivity of 43.1% over MB41(25) are observed, but these over Al-MCM-41(25) are only 61.3% and 13.2%, respectively.

Tertiary butylation of phenol on Cu 1− xCo xFe 2O 4: catalysis and structure–activity correlation

A systematic study of catalytic tertiary butylation of phenol was carried out with isobutene as a function of temperature, feed composition, time on stream, space velocity, and catalyst composition on Cu 1− x Co x Fe 2O 4 ( x=0 to 1) system. Tertiary butylation of phenol gives three products, namely, 2- tert-butyl phenol, 4- tert-butyl phenol, and 2,4-di- tert-butyl phenol. The phenol conversion and selectivity of these products depend on the reaction parameters. A good correlation was found between the activity, in terms of phenol conversion and various product selectivities for this reaction, and the acid–base properties of the catalysts. High activity is achieved with x=0.5 composition, illustrating the importance of a 1:1 combination of Cu and Co and the necessity for optimum concentrations of acid–base centers for this reaction. A reaction mechanism involving the interaction of phenoxide from phenol and the tert-butyl cation from isobutene on Cu 1− x Co x Fe 2O 4 is proposed. X-ray photoelectron spectroscopy and X-ray induced Auger electron spectroscopic analysis of fresh and spent catalysts revealed a partial reduction of metal ions due to reaction. Valence band studies clearly revealed an increase in the overlap of metal ion 3 d bands from fresh to spent catalysts as reflected from a large decrease in the energy gap between them. The better catalytic results observed with x=0.5 are attributed to an optimum distribution of Cu species with heteroatom neighbors, maximum overlap between the Cu and Co 3 d bands, and intermediate acid–base character.

Tertiary butylation of phenol over HY and dealuminated HY zeolites

The catalytic properties of HY and dealuminated HY zeolites in the vapor phase t-butylation of phenol with t-butyl alcohol in the temperature range 100–200 °C are reported. The influence of various reaction parameters such as temperature, space velocity, molar ratio of the reactants are discussed. The main products are p- t-butyl phenol ( p-TBP), o- t-butyl phenol ( o-TBP) and 2,4-di- t-butyl phenol (2,4-DTBP). The product distribution depends on the reaction temperature, number of acid sites and the ratio of Bronsted to Lewis acid sites, which changes with the steaming temperature. Lower molar ratio of reactants and higher space velocity facilitated mono alkylated products.

Vapour phase tertiary butylation of phenol over sulfated zirconia catalyst

Vapour phase butylation of phenol was carried out over a sulfated zirconia solid superacid catalyst in the temperature range 448–473 K using t-butyl alcohol as the alkylating agent. A good substrate (phenol) conversion and excellent product (para-tertiary BP) selectivity was obtained. The catalytic activity remains nearly the same on repeated use of the catalyst. Further, the catalyst was not deactivated when the reaction was carried out for a longer duration, i.e., even after several hours of reaction.