The structure property is the fundamental factor in determining the stability, adsorption, catalytic performance, and selectivity of microporous materials. Seven density functional approximations (DFAs) are used to simulate the crystal structure of microporous material for examining the efficiency and accuracy. In comparison with the existing zeolites, microporous materials with CHA framework are selected as the testing model. The calculation results indicate that the least lattice volume deviation is 5.18/2.72 Å3 from PBE_mGGA, and the second least is −5.55/−10.36 Å3 from LDA_PP. Contrary to USPP_LDA, PBE_GW, PAW_PBE, and PAW_GGA overestimate the lattice volume by ~15.00–20.00 Å3. For each method, RMS deviations are less than 0.016 Å for bond length and less than 2.813° for bond angle. To complete the crystal structure calculation, the CPU time reduces in order of USPP_GGA > PBE_GW > PAW_GGA, PBE_mGGA > PAW_PBE > LDA_PP > USPP_LDA. For two testing models, when the calculation time is not important, PBE_mGGA is the best choice, and when the tradeoff between accuracy and efficiency is considered, LDA_PP is preferred. It seems feasible and efficient to simulate the zeolite structure through E-V curve fitting, full optimization, and phonon analysis bythe periodic density functional theory.

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Periodic Density Functional Theory (PDFT) Simulating Crystal Structures with Microporous CHA Framework: An Accuracy and Efficiency Study

Unveiling the Anti-Trap Effect for Bridging Intermediates on ZnAlOx/AlPO-18 Bifunctional Catalysts to Boost Syngas to Olefin Conversion

The Promotional Role of Potassium on InZr/SAPO-34 for Syngas to Light Olefins

A series of Mo-Co-K sulfide catalysts were prepared with the assistance of different surfactants, and these catalysts were used in CO2 hydrogenation. It was found that the surfactant type had a significant impact on the properties and catalytic performance of these catalysts. When cetyl trimethyl ammonium bromide (CTAB, a cationic surfactant) was used in the synthesis, the steric hindrance effect of micelles and the electrostatic interaction between micelles and ions in the solution would reduce the number and length of MoS2-based layers in the catalyst, thus exposing more “edges” related to the active site. Moreover, CTAB, being a carbon source, was able to promote the generation of carbon species in the catalysts, beneficial for the adsorption of CO2 on the catalyst surface. Under the optimal conditions (320°C, 5.0 MPa, V(H2)/V(CO2) = 3, GHSV = 3000 ml•gcat−1•h−1), the catalyst showed a CO2 conversion of 26.9%, a total alcohol selectivity of 83.7% (excluding CO), and a C2+ alcohol selectivity of 17.7% (excluding CO). Sodium dodecyl benzene sulfonate (SDBS, an anionic surfactant) and polyvinyl pyrrolidone (PVP, a non-ionic surfactant) were also attempted for the preparation of Mo-Co-K sulfide catalysts for comparison. 

Lin Zhang

Papers

The Promotional Role of Potassium on InZr/SAPO-34 for Syngas to Light Olefins

Unveiling the Anti-Trap Effect for Bridging Intermediates on ZnAlOx/AlPO-18 Bifunctional Catalysts to Boost Syngas to Olefin Conversion

Surfactant-assisted preparation of Mo-Co-K sulfide catalysts for the synthesis of low-carbon alcohols via CO2 hydrogenation