Separating Binary Gaseous Mixtures of Ethene + Ethyne Using Cement Hydrate: A Multiscale Computational Study

Cement production is a carbon intensive industry and is responsible for large quantities of greenhouse gases released into the atmosphere. Due to the significant embedded carbon costs of cement, it might be promising to investigate waste cement for alternative uses so as to maximize utility of this material. Recent computational work on the sorption of natural gas constitutions in cement hydrate suggested that it might be worthwhile examining its usefulness in separating mixtures of C₂ hydrocarbons. In light of this and the ongoing challenges of separating ethene and ethyne in industry, this study employed a multiscale approach to assess the feasibility of pressure swing adsorption to separate mixtures of ethene + ethyne. By combining stochastic atomistic simulations with macroscale batch equilibrium modeling, ethene recovery, product gas composition, and the separation power were computed over a range of temperatures (from 273 to 323 K), pressures (100 to 2000 kPa), and adsorbent masses (10 to 40 g per mole of feed gas). The results of this study include a look at the intermolecular interactions in the system and their relationship to the adsorption behavior as described by well-known adsorption isotherm models. This can help point the way to selecting materials that are promising for gas separations.