Mass-Transfer Effects in Liquid-Phase Alkylation of Benzene with Zeolite Catalysts

Abstract

The alkylation of benzene with light hydrocarbons over an acidic catalyst is an important industrial process. Metal halides and solid phosphoric acid have been the most commonly used acid catalysts for this purpose, while zeolite catalysts are excellent, environmentally clean alternatives. Although liquid-phase alkylation with certain synthetic zeolites has been established commercially (such as in catalytic distillation), little has been published on the fundamental parameters governing the reaction kinetics. This paper examines the effect of external (liquid−solid) and internal (pore diffusion) mass transfer on the main reaction of benzene alkylation with ethylene and propylene using various zeolite catalysts. The results and its implications on the effective catalyst utilization will be presented. This constitutes one of the series of basic studies in an effort to optimize aromatic alkylation reactor systems such as catalytic distillation.

Adsorption and diffusion of benzene in the nanoporous catalysts FAU, ZSM-5 and MCM-22: A molecular dynamics study

“…The product, cumene, can then be converted to phenol and acetone by peroxidation. The former is an important petrochemical used in the phenolic resins, nylon, and many other chemicals [5,6]. A new high silica zeolite, MCM-22, has also been claimed to be a good catalysts for cumene synthesis [7][8][9].…”

Alkylation of Benzene Using Batch and Continuous Fixed-Bed Reactors

“…However, the different external flow conditions of the different reactors change the external mass transfer rates. Since the alkylation reaction to produce cumene is relatively fast, the difference in concentration between the surface of the catalyst and the bulk fluid, and thus the external mass transfer resistances, is important (Ercan et al, 1998). The higher fluid velocities of the forced gas flow of the continuous fixed-bed reactor may allow for lower external mass transfer resistance, creating a positive effect in the catalyst activity.…”

Liquid-Phase Alkylation of Benzene with Propylene Catalysed by HY Zeolites

“…The influence of liquid-solid mass transfer and pore diffusion on the global process kinetics were checked by using the Mears' and Weisz-Prater' criteria [11,12]. Mears' criterion states that when the following inequality is satisfied, external mass transfer influence is negligible:…”