An atomistic model of a disordered nanoporous solid: Interplay between Monte Carlo simulations and gas adsorption experiments

Abstract

A combination of physisorption measurements and theoretical simulations was used to derive a plausible model for an amorphous nanoporous material, prepared by Friedel-Crafts alkylation of tetraphenylethene (TPM), leading to a crosslinked polymer of TPM connected by methylene bridges. The model was refined with a trial-and-error procedure, by comparing the experimental and simulated gas adsorption isotherms, which were analysed by QSDFT approach to obtain the details of the porous structure. The adsorption of both nitrogen at 77 K and CO2 at 273 K was considered, the latter to describe the narrowest pores with greater accuracy. The best model was selected in order to reproduce the pore size distribution of the real material over a wide range of pore diameters, from 5 to 80 Å. The model was then verified by simulating the adsorption of methane and carbon dioxide, obtaining a satisfactory agreement with the experimental uptakes. The resulting model can be fruitfully used to predict the adsorption isotherms of various gases, and the effect of chemical functionalizations or other post-synthesis treatments.

On the Gas Storage Properties of 3D Porous Carbons Derived from Hyper-Crosslinked Polymers

“…UPO8 and UPO16 were also activated chemically with KOH at high temperatures, causing the carbonization of the materials: this is an effective method for the preparation of highly microporous materials. The activation mechanism occurs as a stoichoimetric solid–solid/solid–liquid reaction [63,64], according to equation 6KOH + 2C → 2 K + 3H 2 + 2K 2 CO 3 . With the increase of the activation temperature above 700 °C, the resulting K 2 CO 3 starts to decompose into K 2 O and CO 2 .…”

“…Obtaining a reliable model of HCP amorphous structures is a very complex task. Recently, the UPO network was modeled by a trial-and-error procedure, based on the simulation of N 2 and CO 2 adsorption in different tentative models of suitable stoichiometry, compared with experimental uptake [64]. A snapshot of the structure proposed by this procedure is shown in Figure 2.…”

Modeling Amorphous Microporous Polymers for CO2Capture and Separations

“…493 In this particular case, an amorphous model overpredicted CO 2 uptake when compared with experimental results, indicating that the model can be further improved. Canti et al 497 explored various methodologies for constructing amorphous mPAFs by using the Polymatic simulated polymerization. 280 They explored various degrees of monomer complexity to obtain realistic pore size distributions and were able to improve the accuracy of predicted CH 4 and CO 2 uptake in mPAFs.…”

“…Computational studies have also been performed on microporous aromatic frameworks (mPAFs), which were synthesized experimentally based on Friedel–Crafts condensation of tetraphenylmethane (TPM) and formaldehyde dimethyl acetal (FDA). , The simulated and experimental adsorption isotherms deviated significantly, even though the authors state that the force field in this work was optimized to correctly describe interactions between CO 2 and PAFs. For example, the simulations predicted loading capacities of 125 and 210 cm 3 (STP)/g at 298 K and 1 and 10 bar, respectively, compared to experimental values of 38 and 136 cm 3 (STP)/g .…”

A Porous Carbon with Excellent Gas Storage Properties from Waste Polystyrene

“…Analogous procedures were recently employed to prepare porous carbons from HCP [36,37,38,39,40]. We have also followed this approach in the past starting from tetraphenylmethane, testing different reaction conditions to optimize the textural properties of the products [31,41,42].…”