Research into a gas sensing material with excellent performance to detect or remove toxic phosgene (COCl₂) is of great significance to environmental and biological protection. In the present work, the adsorption performance of COCl₂ on pristine phthalocyanine (Pc) and metal-decorated Pc (MePc, Me = Cu, Ga, and Ru) monolayers was studied by first-principles calculations. The results show that the absorption process of COCl₂ on pristine Pc and CuPc both belong to physisorption, indicating that they are not suitable gas sensing materials for COCl₂. When Pc sheets are decorated by Ga and Ru atoms, the adsorption of COCl₂ is changed into chemisorption, and the corresponding adsorption energies are -0.57 and -0.50 eV for GaPc and RuPc, respectively. The microcosmic mechanism between COCl₂ and adsorbents (GaPc, RuPc) was clarified by the analysis of the density of states, the charge density difference, and the Hirshfeld charge. In addition, the COCl₂ adsorption results in a significant conductivity variation of the RuPc monolayer, demonstrating it exhibits a high sensitivity to the COCl₂ molecule. Meanwhile, quick desorption processes were noticed at various temperatures for the COCl₂/RuPc system. Consequently, the RuPc monolayer can be considered as a potential candidate for phosgene sensors because of the moderate adsorption strength, high sensitivity, and fast desorption speed.

The design of the good-performance materials for toxic formaldehyde (CH₂O)-gas-detection is critical for environmental preservation and human health. In this work, density functional theory (DFT) calculations were employed to investigate the adsorption behavior and electronic properties of CH₂O on transition metal (TM)-doped phthalocyanine monolayers. Our results prove that PdPc and RuPc monolayers are thermodynamically stable. Analysis of the adsorption energy showed that the CH₂O gas molecule was chemisorbed on the RuPc monolayer, while it was physisorbed on the PdPc nanosheet. The microcosmic interaction mechanism within the gas-adsorbent system was revealed by analyzing the density of states, the charge-density difference, the electron-density distribution, and the Hirshfeld charge transfer. Additionally, the RuPc monolayer was highly sensitive to CH₂O due to the obvious changes in electrical conductivity, and the recovery time of CH₂O molecule was predicted to be 2427 s at room temperature. Therefore, the RuPc monolayer can be regarded as a promising gas-sensing material for CH₂O detection.

The hydrochlorination process is a necessary technological step for the production of polycrystalline silicon using the Siemens method. In this work, the adsorption behaviors of silicon tetrachloride (SiCl₄), silicon dichloride (SiCl₂), dichlorosilane (SiH₂Cl₂), trichlorosilane (SiHCl₃), HCl, and H₂ on the Si(100) surface were investigated by first-principles calculations. The different adsorption sites and adsorption orientations were taken into account. The adsorption energy, charge transfer, and electronic properties of different adsorption systems were systematically analyzed. The results show that all of the molecules undergo dissociative chemisorption at appropriate adsorption sites, and SiHCl₃ has the largest adsorption strength. The analysis of charge transfer indicates that all of the adsorbed molecules behave as electron acceptors. Furthermore, strong interactions can be found between gas molecules and the Si(100) surface as proved by the analysis of electronic properties. In addition, SiCl₂ can be formed by the dissociation of SiCl₄, SiH₂Cl₂, and SiHCl₃. The transformation process from SiCl₄ to SiCl₂ is exothermic without any energy barrier. While SiH₂Cl₂ and SiHCl₃ can be spontaneously dissociated into SiHCl₂, SiHCl₂ should overcome about 110 kJ/mol energy barrier to form SiCl₂. Our works can provide theoretical guidance for hydrochlorination of SiCl₄ in the experimental method.

Exploring the fluidization behaviors and chemical performance in silicon tetrachloride (SiCl₄) hydrochlorination processes within a fluidized bed reactor (FBR) poses significant challenges. In this study, we developed an Eulerian-granular model (EGM) by integrating the Eulerian–Eulerian two-fluid model with the kinetic theory of granular flow (KTGF). The effect of fluidization velocities on the flow regime, heat transfer, and chemical reaction performance were investigated. The applicability of the simulation method and the validity of the model were confirmed through comprehensive comparisons, including the simulated values of the maximum bed expansion height (H_max) with theoretical values derived from empirical formulas and the simulated gas temperature profile with Hsu’s experimental data. The results indicate that the present EGM can be feasible to describe the variation of the flow regime within the FBR. An increase in bed voidage over time, coinciding with transitions in the flow regime, can be observed. Particularly noteworthy was the attainment of a more uniform distribution of SiCl₄ under the bubbling fluidization state. Furthermore, the FBR possess high heat transfer characteristics, and the reaction gas can reach the set temperature of the bed after entering a small distance (about 10 mm). The presence of circulating bubbles within the FBR enhances the mixing uniformity of the SiCl₄ reaction gas and silicon particles, particularly in the central and upper regions of the bed under the bubbling fluidization state. As a result, the predicted highest concentration of SiHCl₃ was 13.08% and the conversion rate of SiCl₄ was 28.97% under the bubbling fluidization state. Our results can provide a theoretical basis for further understanding of the hydrochlorination process of SiCl₄ within the FBR.

Recent advances in petroleum exploration have revealed that the vertical zonality in hydrogeochemistry may be reversed to varying degrees in oil and gas-bearing formations. In the petroleum basins in eastern China, the regional groundwater is dominated by a sodium bicarbonate water poor in calcium. Moreover, there is clearly a negative correlation between the contents of Ca and HCO₃ in the groundwater. This correlation may become more distinct near petroleum accumulations, resulting in a stronger reversal of vertical zonality in hydrogeochemistry. For example, in the Songliao basin, the eastern part of Northern China and East China Sea, total salinity of the deep oil field water may decrease with depth. Although various factors can lead to the decrease in total salinity, the three important ones are (1) thermal dehydration of clay minerals in the argillaceous rock; (2) bacterial sulfate reduction in shallow formations; (3) thermo-chemical sulfate reduction in deep formation.