1,2,4-Trimethylbenzene Transformation Reaction Compared With Its Transalkylation Reaction With Toluene Over USY Zeolite

1,2,4-Trimethylbenzene (TMB) transalkylation with toluene has been studied over USY zeolite type catalyst using a riser simulator that mimics the operation of a fluidized-bed reactor. Reaction mixtures of 50:50 wt % TMB and toluene were used for the transalkylation reaction. The range of temperature investigated was 400-500 degrees C with time on stream ranging from 3 to 15 s. The effect of reaction conditions on the variation of the p-xylene to o-xylene product ratio (P/O), distribution of trimethylbenzene (TMB) isomers (1,3,5-TMB to 1,2,3-TMB), and values of xylene/tetramethylbenzene (X/TeMB) ratios are reported. Comparisons are made between the results of the transalkylation reaction with the results of pure 1,2,4- TMB and toluene reactions earlier reported. Toluene, which was found almost inactive, became reactive upon blending with 1,2,4-TMB. This shows that toluene would rather accept a methyl group to transform to xylene than lose a methyl group to form benzene under the present experimental conditions. The experimental results were modeled using a quasi-steady-state approximation. Kinetic parameters for the 1,2,4-TMB disappearance during the transalkylation reaction and in its conversion into isomerization and disproportionation products were calculated using the catalyst activity decay function based on time on stream (TOS). The apparent activation energies were found to decrease as follows: E-transalkylation > E-isomerization > E-disproportionation

Catalytic Transformation Of C-7-C9 Methyl Benzenes Over USY-Based FCC Zeolite Catalyst

Catalytic transformation of three methyl benzenes (toluene, m-xylene, and 1,2,4- trimethylbenzene) has been investigated over USY-based FCC zeolite catalyst in a novel Riser Simulator at different operating conditions. The effect of reaction conditions on the variation of isomerization to disproportionation products ratio (I/D), distribution of trimethylbenzene (TMB) isomers (1,3,5-to-1,2,3-) and values of pxylene/ o-xylene (P/O) ratios are reported. The sequence of reactivity of the three alkyl benzenes was found to decrease as the number of methyl group per benzene ring decreases, as follows: 1,2,4-trimethylbenzene > m-xylene > toluene. This is true at all temperatures investigated over the USY zeolite. Toluene was found unreactive in our reaction condition. Effectiveness factor (eta(ss)) of both 1,2,4-TMB and m-xylene have been estimated. While m-xylene's eta(ss) was close to unity at all condition, 1,2,4-TMB's eta(ss) was less than that of m-xylene. The effectiveness factor was estimated from the quasi-steady state approximation modeling of the experimental data involving a decay function based on 'Time on Stream' (TOS). Based on the present study, it was found that the number of methyl groups has the most important role on the reactivity of 1,2,4-TMB, m-xylene and toluene over Y-based catalyst

Alternative Approaches to the Equilibrium Properties of Hard-Sphere Liquids

An overview of some analytical approaches to the computation of the structural and thermodynamic properties of single component and multicomponent hard-sphere fluids is provided. For the structural properties, they yield a thermodynamically consistent formulation, thus improving and extending the known analytical results of the Percus–Yevick theory. Approximate expressions for the contact values of the radial distribution functions and the corresponding analytical equations of state are also discussed. Extensions of this methodology to related systems, such as sticky hard spheres and squarewell fluids, as well as its use in connection with the perturbation theory of fluids are briefly addressed.