# Coke Deposition in CHA Zeolite Predicted by CO2 Adsorption Isotherms and Molecular Simulation

## TL;DR

This paper uses CO2 adsorption and simulations to predict and understand coke buildup in CHA zeolites, which are important in industrial processes.

## Contribution

A predictive molecular simulation model for CHA zeolite with multiple cations, validated by CO2 adsorption data, is developed.

## Key findings

- N-heptane best represents coke molecules in the deactivation process of CHA zeolites.
- CO2 adsorption isotherms combined with simulations can identify the nature of coke molecules.
- The method can be applied to other molecular sieves and coke models.

## Abstract

Molecular sieves
used in catalytic and adsorptive processes in
the petroleum/petrochemical industry are subject to deactivation by
coke deposition. Here, we apply CO2 adsorption isotherms
associated with molecular simulation models to extract additional
information from the coke deactivation process. We developed a predictive
molecular simulation model for naturally occurring zeolite CHA with
multiple cation mixtures. The model was validated based on experimental
CO2 adsorption isotherms. N-heptane, benzene
and naphthalene were tested as model coke molecules to describe deactivation
as a function of carbon concentration. The n-heptane
molecule was the one that best represented coke from the available
experimental data. In addition to predicting deactivation, the combined
use of CO2 adsorption isotherms with the molecular simulation
model can discriminate the nature of coke molecules. The procedure
described can be applied to other molecular sieve structures, in catalysis
and adsorption, and to other model molecules for coke.