(104a) Transport and Kinetic Studies in Solid Acid Alkylation Processes

Commercial alkylation processes to produce desired heavier hydrocarbon (2,2,4 tri-methyl-pentane has research octane number of 100) use concentrated liquid sulfuric acid or anhydrous hydrogen fluoride as the catalysts at sub-ambient temperature with a mixture of butene highly diluted in isobutane. During last two decades, increasing safety and environmental concerns associated with use of these toxic acids and the disposal of their related acid soluble oil have led to alternative technologies based on solid acid catalysis.

Zeolites are active alkylation catalysts, giving product distribution similar to those characteristics of the liquid acids, but their unacceptably rapid deactivation was and still is the obstacle to commercialization (Feller and Lercher 2004). Zeolites are crystalline microporous materials mainly composed of silicon and oxygen atoms. How does organic molecule diffuse inside a zeolite and how does the intra-particle and intra-crystalline channel network of a zeolite influence the diffusion, adsorption/desorption and reaction pathway of organic molecules are necessarily important questions in solid acid alkylation processes.

The objectives of the current work are to understand and exploit different phenomena taking place during alkylation of iso-butane and n-butene on zeolites. Different particle sizes and pore morphologies of the zeolites are tested to enhance the understanding of the dynamics of the reactants and products in solid acid alkylation. The understanding gained should help in quantifying the key features needed for improved catalyst and regeneration and for selecting the optimal operation for solid acid alkylation processes.

References:

Feller A. and Lercher J. A., (2004). Chemistry and technology of isobuatne/ alkene alkylation catalyzed by liquid and solid acids. Adv. Catal. 48 229-295.