Accurate van der Waals force field for gas adsorption in porous materials

Abstract

An accurate van der Waals force field (VDW FF) was derived from highly precise quantum mechanical (QM) calculations. Small molecular clusters were used to explore van der Waals interactions between gas molecules and porous materials. The parameters of the accurate van der Waals force field were determined by QM calculations. To validate the force field, the prediction results from the VDW FF were compared with standard FFs, such as UFF, Dreiding, Pcff, and Compass. The results from the VDW FF were in excellent agreement with the experimental measurements. This force field can be applied to the prediction of the gas density (H , CO , C H , CH , N , O ) and adsorption performance inside porous materials, such as covalent organic frameworks (COFs), zeolites and metal organic frameworks (MOFs), consisting of H, B, N, C, O, S, Si, Al, Zn, Mg, Ni, and Co. This work provides a solid basis for studying gas adsorption in porous materials. © 2017 Wiley Periodicals, Inc.

Performance of density functionals for modeling vapor liquid equilibria of CO2 and SO2

“…Conventional technologies (such as ammonia scrubbing, solvent absorption) to remove these gases have certain disadvantages such as, high energy cost, corrosion, solvent loss, degradation, and byproducts production . The development of new materials, ionic liquids, and modification of industrial processes are an ongoing effort by researchers to efficiently capture these gases . Our ability to model these sorption processes using a first principles approach can have significant impact in speeding up the discovery process.…”

The Origin of the Reproduction of Different Nitrogen Uptakes in Covalent Organic Frameworks (COFs)

“…Because of all DBA-COFs being periodic networks containing over 100 atoms in au nit cell, it is impossible to take whole crystals as the objects in achieving ac omplete set of parameter of suitable interatomic potential forms to fit the first-principles force field. [18,27] Considering the common repeat parts in the structure of DBA-COFs, the fragments of DBA [12] and PDBA (C 2 -symmetric pyrene-2,7-diboronic acid) were cut from DBA-COFs, which are selected to represent the whole structure in the simulation procedure. In addition, seven types of atoms, including three types of carbon, two types of hydrogen, and one type of boron, were defined to model gas sorption segments and further the whole COFs.…”

“…Starting from two triangular monomers and three two‐site linkers, a series of newly synthesized boron‐based COFs, including two‐dimensional and three‐dimensional COFs (Py‐DBA‐COF1, Py‐MV‐DBA‐COF2, Py‐DBA‐COF2, DBA‐COF1, DBA‐COF2 and DBA‐3D‐COF) are investigated in this work, as shown in Figure . Because of all DBA‐COFs being periodic networks containing over 100 atoms in a unit cell, it is impossible to take whole crystals as the objects in achieving a complete set of parameter of suitable interatomic potential forms to fit the first‐principles force field . Considering the common repeat parts in the structure of DBA‐COFs, the fragments of DBA[12] and PDBA ( C 2 ‐symmetric pyrene‐2,7‐diboronic acid) were cut from DBA‐COFs, which are selected to represent the whole structure in the simulation procedure.…”

“…where r i,j is the distance between atoms i and j , ϵ represents the depth of the potential well, σ i,j is the interatomic distance at which the potential is zero, Q i and Q j are the electric charge of atoms i and j , respectively. The charges of DBA‐COFs are obtained using Q eq method based on Ewald sums, ϵ 0 is the electrical permittivity. The force fields and charges of N 2 are adopted for the TraPPE force field with 3‐site model (Table S1 in Supporting Information) …”

A DFT Screening of M-HKUST-1 MOFs for Nitrogen-Containing Compounds Adsorption

“…Despite the extensive experimental studies on the adsorption performance of NCCs on HKUST-1, only a few theoretical researches have focused on NCCs’ adsorption behavior in MOFs. A lot of theoretical work has studied the adsorption in various MOFs of small molecules such as CO 2 [ 20 , 21 , 22 ], SO 2 [ 23 , 24 ], dibenzothiophene [ 25 ], CH 4 [ 21 , 26 , 27 ], N 2 [ 21 ], N 2 O [ 28 ], H 2 [ 21 ], and noble gas [ 29 ]. To our best knowledge, a systematic study on the adsorption of three NCCs (NO, NO 2 , and NH 3 ) on 19 metal-substituted variants of HKUST-1 is still missing.…”