The adsorption of hydrocarbons in porous materials : a computational study

• Main Author: Fox, Joseph
• Published: University of Edinburgh 2005
• Subjects: 622
• Online Access: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.651067

In this work, Monte Carlo computer simulations are used to study hydrocarbon molecules (linear, branched and cyclic) within the pores of four different porous material: three zeolites (silicalite-1, AIPO₄-5 and ITQ-22) and one mesopore (MCM-41). The three zeolites have different compositions and pore structures and include an extremely well known and widely used structure (silicalite-1), a recently synthesised zeolite with a complex pore structure (ITQ-22) and a zeolite with a simple, one dimensional pore structure (AIPO₄-5). The mesopore, MCM-41, has pores which are an order of magnitude larger than the zeolites and can therefore accommodate many more hydrocarbons within its porous network. The adsorption characteristics of the three hydrocarbons in the zeolites are simulated and compared with the available experimental data. Binary and ternary mixtures of the hydrocarbons are also studied and the temperature dependence of the selectivity of each zeolite is discussed and an explanation given for any reversal in selectivity at high temperature. Ideal Adsorption Solution Theory is used to predict the behaviour of mixtures in zeolites and the results of the theory are compared with the simulations. A new computational model for MCM-41 is introduced and used to study the adsorption of hydrocarbons within its pores. The results are compared with experiments (where possible) and the structure of the adsorbed molecules is investigated. Possible refinements to the model are proposed and their effect on the adsorption properties discussed.