Yunfeng Liang

Carbon dioxide (CO₂) capture and storage (CCS) is an important climate change mitigation option along with improved energy efficiency, renewable energy, and nuclear energy. CO₂ geosequestration, that is, to store CO₂ under the subsurface of Earth, is feasible because the world's sedimentary basins have high capacity and are often located in the same region of the world as emission sources. How CO₂ interacts with the connate water and minerals is the fo

Contrary to ordinary solids, which are normally known to harden by compression, the compressibility of $\mathrm{Si}{\mathrm{O}}_{2}$ (silica) glass has a maximum at about $2--4\phantom{\rule{0.3em}{0ex}}\mathrm{GPa}$ and its mechanical strength shows a minimum around $10\phantom{\rule{0.3em}{0ex}}\mathrm{GPa}$. At this pressure, the compression of silica glass undergoes a change from purely elastic to plastic, and samples recovered from above $10\phantom{\rule{0.3em}{0ex}}\mathrm{GPa}$ are found

The general aim of this study is to test the reliability of polarizable model potentials for the prediction of vibrational (infrared and Raman) spectra in highly anharmonic systems such as high temperature crystalline phases. By using an ab initio parametrized interatomic potential for SiO2 and molecular dynamics simulations, we calculate the infrared and Raman spectra for quartz, cristobalite, and stishovite at various thermodynamic conditions. The model is found to perform very well in the pre

The transformation of SiO2 from low pressure tetrahedral phases into denser octahedral phases takes place via the collapse of the oxygen sublattice into a close-packed arrangement. The transition paths and the resulting products are known to be affected by the presence of anisotropic stresses, which are difficult to control, so interpretation of the experimental results is problematic. Based on nonhydrostatic molecular dynamics simulations, we show that the collapse of the oxygen sublattice in t

With the continuous development of shale gas, CO2 storage in shale gas reservoirs has gained significant attention due to the massive available space in these reservoirs. These shale formations exhibit a complex pore structure with micropores (<2 nm) and mesopores (2–50 nm), which profoundly influence gas sorption behaviors. This work used grand canonical Monte Carlo to study the sorption behavior of CH4, CO2, and their binary mixtures (from 1:9 to 9:1) in kerogen nanopore systems with mesopores

Carbon capture and storage (CCS) in subsurface reservoirs represents a highly promising and viable strategy for mitigating global carbon emissions. In the context of CCS implementation, it is particularly crucial to understand the complex molecular diffusive and adsorptive behaviors of anthropogenic carbon dioxide (CO₂) in the subsurface at the nanoscale. Yet, conventional molecular models typically represent only single-slit pores and overlook the complexity of interconnected nanopor

Annealing to several hundred Kelvin has been recently shown to induce densification in compressed SiO2 glass. By means of an ab-initio parameterised interatomic potential for SiO2 and molecular dynamic simulations, we studied the structural properties of compressed glass by cold compression at room temperature and by quenching the liquid at selected pressures. The noticeable differences found below 10 GPa between the two results are interpreted in the context of the experimentally reported tempe

Geochemical trapping (i.e., mineralization) is considered to be the most efficient way for long-term CO2 storage in order to mitigate "global warming effect" induced by anthropogenic CO2 emission. The common view is that the reaction process takes hundreds of years; however, recent field pilots have demonstrated that it only took 2 years to convert injected CO2 to carbonates in reactive basaltic reservoirs. In this work, ab initio molecular dynamics simulations were employed to investigate chemi

First-principles molecular dynamics calculations were performed to investigate the mechanism on thermal decomposition of H2 of ammonia borane (NH3BH3) at ambient and high pressure. Under atmospheric pressure, one H2 molecule was released through an intramolecular reaction of a single NH3BH3. Nudged elastic band calculations show that the activation barrier for the decomposition in the crystalline environment is reduced by almost 1/3 from the gas phase value. When the system is heated under press

In a shale gas and oil reservoir, hydrocarbon fluids are stored in organic nanopores with sizes on the order of ∼1–100 nm. The adsorption, selectivity, and phase behavior of hydrocarbons in the nanopores are crucial for estimating the gas-in-place and predicting the productivity. In this study, to understand the characteristics of the phase behavior of multicomponent hydrocarbon systems in shale reservoirs, the phase behavior of a CH4/n-C4H10 binary mixture in graphite nanopores was investigated