Side-chain Alkylation Of Toluene Research Articles

Side chain alkylation of toluene with isopropanol and methanol over alkali exchanged zeolites

Alkylation of toluene with isopropanol and methanol has been studied over alkali cation exchanged β, Y and ZSM-5 zeolites. Over Li exchanged zeolites isopropylation takes exclusively place at the nucleus, resulting in cymenes while methylation gives xylenes and ethylbenzene, the former being the major product. Over Na, K and Cs exchanged zeolites both isopropylation and methylation occurs at the side chain, resulting in isobutylbenzene from the former and ethylbenzene and styrene from the latter. Optimum temperatures were 648 K for isopropylation and 698 K for methylation. Formaldehyde gives ethylbenzene with an considerable amount of styrene over all the cations except the Li exchanged catalysts, while acetone gives isobutyl benzene only over NaY, KY and CsY. Over as-synthesised and Li exchanged zeolites, ethylbenzene is formed by direct dehydrocondensation of methanol and toluene while over K and Cs exchanged zeolites, ethylbenzene is formed via HCHO and styrene intermediates. Isobutyl benzene resulted by direct dehydrocondensation of isopropanol and toluene over alkali exchanged β and ZSM-5 while over alkali exchanged Y it is formed through acetone intermediates. By comparing the data obtained by poisoning the catalyst by aniline and phenol and also the data obtained by the adsorption of NH 3 and CO 2 with the partial charge on the frame work oxygen, it is concluded that the side chain alkylation of toluene is a cooperative action of both acidic and basic sites

Side-chain alkylation of toluene with methanol over zeolite catalysts

Catalytic properties of NaX-type zeolites modified by alkali metal cations under hydrothermal conditions have been studied. The highest process efficiency is obtained for CsNaX catalysts. The effect of operation conditions on the process results was examined.

Side-chain alkylation of toluene by methanol over a basic zeolite: a kinetic study

A few X zeolites, exchanged with K and/or Cs, were tested as catalysts for the reaction of toluene with excess methanol (mole ratio methanol/toluene from 5 to 19) in a fixed bed reactor. Very high selectivity for the side-chain alkylation to ethylbenzene and styrene was observed. A kinetic study of the reaction at 350 C over a CsNaX catalyst was performed: the reaction rate was found to be negatively affected by a high concentration of methanol and by the addition of small amounts of ethylbenzene or styrene to the feed. Some kinetic models, able to represent such inhibition phenomena, were compared on the basis of optimization procedures.

Application of computer graphics to catalyst design

The suitability of computer graphics for the investigation of the structure and function of heterogeneous catalysts has been demonstrated with supported Perovskite oxide catalysts, supported vanadium oxide catalysts, supported gold catalysts, and acid-base cooperative catalysis in the side-chain alkylation of toluene with methanol on alkali-ion exchanged zeolites. Computer graphics is especially effective for discussing the geometrical factors relevant to catalysis and catalyst formulation.

Side-chain alkylation of toluene with methanol on KX/KZSM-5 binary zeolite catalysts

The side-chain alkylation of toluene with methanol catalyzed by the modified binary zeolite catalysts of KX and Al2O3, KX, KY, KM, or KZSM-5 has been studied. It was found that the selectives of styrene increased with the partial charge on the (A104)− tetrahedra in the second zeolite component. The KX/KZSM-5 binary zeolite catalysts had much higher activities than did the separate zeolite catalysts, and the catalytic properties were greatly improved after H3BO3 and KOH modifications. Comparing the alkylation data with the t.p.d. measurements of NH3 and CO2, Sanderson's electronegativity, and the partial charge on the (A104)− tetrahedra, it is concluded that the side-chain alkylation of toluene with methanol on the binary zeolite catalysts is an acid-base cooperative, selective reaction.

Base catalysis by alkali modified zeolites: III. Alkylation with methanol

Ion exchanged CsNaX and CsNaY, cesium acetate impregnated CsNaX ( CsAce CsNaX ) and CsNaY ( CsAce CsNaY ), and MgO have been reacted with isopropanol at 425 °C and atmospheric pressure to assess their acid/base properties at a temperature consistent with that used in the side chain alkylation of toluene with methanol. The results suggest that the ability of the catalysts tested here to promote a base mediated reaction follow the order of MgO > CsAce CsNaY > CsAce CsNaX ⋍ CsNaY > CsNaX . Selectivities to acetone measured at 4.73% conversion follow this order as well, ranging from 95.7% and 93.9% for MgO and CsAce CsNaY , respectively, to 17.6% for the CsNaX. Thus, these catalysts can be grouped into two categories: (i) catalysts which vary in acid/base properties yet possess identical topology (e.g., the zeolites) and (ii) catalysts which vary in topology yet have similar acid/base properties (e.g., MgO and CsAce CsNaY ). These catalysts were compared using the side chain alkylation of toluene, ethane, methane, and acetone with methanol. For the impregnated zeolites, similar toluene conversions were observed. Unlike the impregnated X zeolite, no formaldehyde (i.e., the alkylating agent) was observed in the product stream of the impregnated Y zeolite. Both MgO and CsAce CsNaY had similar methanol decomposition products; i.e., no formaldehyde and high CO formation, yet unlike CsAce CsNaY no toluene conversion was observed for MgO. No conversion of ethane or methane was observed for either impregnated zeolite at 425 °C. Attempts at higher temperatures (e.g., 465 °C) failed also. Acetone was alkylated to methyvinylketone and methylethylketone; however, the majority of the reacted acetone formed products which appear to result from acetone aldol condensations.

Promotion role of some metals (Cu, Ag) in the side chain alkylation of toluene by methanol

The side chain alkylation of toluene by methanol is favoured by metallic promotors (Cu, Ag) deposited on ceasium exchanged and boron doped zeolite 13X but also by the use of hydrogen as carrier gas. A reaction scheme is proposed.

Side-chain alkylation of toluene with methanol over Cs2O-activated carbon catalyst

The side-chain alkylation of toluene to form ethylbenzene or styrene has been investigated using a conventional flow reactor at temperatures near 475°C. Cs2O (10–20 wt. %)-activated carbon catalyst prepared by an impregnation method showed an excellent activity and selectivity. The calcination temperature of the catalyst and the addition of CO2 or H2O into the reactant mixture affected the catalyst activity in a striking manner.

A Study of Catalysis by Metal Phosphates. V. The Alkylation of Toluene with Methanol over Metal Phosphate Catalysts

Abstract The side chain alkylation of toluene with methanol over the catalyst of Ca3(PO4)2 or K3PO4 supported on active carbon gave more ethylbenzene than that over MgO. It was found that there are correlations between the catalytic activities and acid-base properties.

Anomalous effect of nitrogen on side-chain alkylation of toluene with methanol over solid bases

The alkylation of toluene with methanol was carried out at 500°C over various base catalysts. The activity of MgO was found to be highest when treated specially with nitrogen. The effect of nitrogen was anomalously large, 8, 8% ethylbenzene and 2.3% styrene being formed.

Side‐Chain Alkylation of Toluene with Ethylene

Side‐Chain Alkylation of Toluene with Ethylene