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• CO 2 -kerogen interaction dominated counter-current diffusion is investigated. • Molecular models of hydrocarbons extraction from kerogen using CO 2 are constructed. • Effects of pressure, temperature, hydrocarbon, and type of kerogen are analyzed. The affinity of CO 2 to kerogen represents an opportunity to increase shale oil/gas recovery using CO 2 , and as well represents great potential for CO 2 sequestration in shale formations. In this study, the CO 2 -kerogen interaction dominated counter-current diffusion was investigated using molecular dynamics simulation. Molecular models of ad-/absorbed hydrocarbons extraction from kerogen using CO 2 were constructed, and the CO 2 -hydrocarbon counter-current displacement processes were simulated. Results showed that the stronger interaction between kerogen and CO 2 than that between kerogen and hydrocarbons results in a spontaneous counter-current diffusion process. That is, the ad-/absorbed hydrocarbons in kerogen can effectively be extracted out and CO 2 can flow into and be stored in kerogen simultaneously. Effects of pressure, temperature, hydrocarbon, and the type of kerogen on the efficiency of hydrocarbon extraction, and CO 2 storage capacity were analyzed. Further, in field applications, methods of evaluating the enhanced hydrocarbon recovery and the CO 2 storage capacity of shale formations were proposed. Results obtained from this study provide guidance for enhancing shale oil/gas recovery using CO 2 and for CO 2 sequestration in shale formations. [ABSTRACT FROM AUTHOR]

• Main carbon, nitrogen and sulfur-precursors are indicated by XPS method. • The same precursors result in close temperatures at which characteristic pollutants occurred. • A full view of transformation mechanism of FCC pollutant emission is presented. Fluid catalytic cracking processes generate various gas pollutants, which are the major concern for environmental protection in refineries. However, the transformation mechanism from deposits to gas pollutants is not well understood. In this work, spent catalysts from different typical FCC units were analyzed to evaluate the effect of pollutant precursors on pollutant emission. The main carbon, nitrogen and sulfur precursors of FCC pollutant emission were identified. Regeneration experiments were conducted to assess the relationship between regeneration temperature and pollutant emission under partial combustion conditions. Results showed that the same precursors from different catalysts result in close temperatures at which characteristic pollutants occurred. VOCs are firstly generated by the coke branches cracking under low temperature. Then, nitrogen-containing compounds convert to NH 3 and HCN, and some of them are oxidized into NO x. After that, sulfur-containing compounds convert to C-S group and H-S group, which finally convert to SO 2 at high temperature. At last, a full view of transformation mechanism of FCC pollutant emission is presented, which will give a further insight into the prediction and control of pollutants. [ABSTRACT FROM AUTHOR]

• Newly designed two-core series tests are conducted, and a new shale oil flow behavior is observed. • A threshold stress change is defined for the mobilization of the oil in organic matter (OM). • Mobilization of the oil in OM is the result of the compression of surrounding inorganic matrix. • Effects of permeability, Young's modulus, pressure drop, and matrix size on oil flow in OM are investigated. Oil in shale formation includes free oil in inorganic pores and ad-/absorbed oil within organic matter (OM). The latter is immobile without exerting extra forces due to the strong molecular interactions between oil and OM. In this study, we conducted newly designed two-core series oil flow experiments with shale and sandstone samples to reveal the mechanisms of mobilizing the oil in OM, and a new phenomenon in shale samples was observed. Analysis using the theory of shale compaction showed that the OM and oil within it are compressed by the inorganic matrix in the depletion process, raising the effective stress of OM and its pore pressure. When the effective stress of OM attains a threshold value, the oil in OM is squeezed out into the surrounding inorganic matrix. For the first time, a threshold stress change of OM is defined, and a model is proposed for describing the mechanisms of mobilizing the oil in OM validated by the experimental results. The values of threshold tress change τ increases from 0.14 MPa to 0.48 MPa with the saturation pressure increasing from 0.51 MPa to 1.47 MPa. Field scale modeling shows that the mobilization of oil in OM is greatly affected by the permeability of OM and inorganic matrix, the stiffness of inorganic matrix, pressure drawdown, and the matrix size. [ABSTRACT FROM AUTHOR]

• Different proportions of MoS 2 /Fe 3 O 4 adsorbents were synthesized. • MoS 2 /Fe 3 O 4 adsorbents show great removal efficiency for mercury. • MF-10 have a higher specific surface area than pure MoS 2. • High specific surface area and lattice oxygen play an important role in mercury removal. • MF-10 has good magnetic and recycling ability. At the front end of the Electrostatic precipitator (ESP), activated carbon injection is a common method to remove mercury from flue gas, but the high cost, low efficiency and non-recyclability limit the practical application of activated carbon. MoS 2 , a transition metal sulfide with a two-dimensional layered structure, was found to have favourable performances in removing contaminant. In this work, Fe 3 O 4 was successfully grown on the surface of flower-like MoS 2 by two-steps hydrothermal methods. The experimental results showed that the specific surface area of MoS 2 /Fe 3 O 4 (MF) was the largest when the ratio is 10 wt% (MF-10). Compared with pure MoS 2 , the specific surface area of MF-10 increased by 6.7467 m2/g, which was attributed to the growth of Fe 3 O 4. At the same time, the introduction of Fe 3 O 4 made the MF possess superparamagnetism to facilitate its retrievability under an external magnetic field. In addition, MF-10 also showed a mercury removal efficiency of almost 100%. Although the efficiency of the MF-10 has decreased after 5 cycles and 24 h, it could still maintain about 90%, revealing a stable cycle life. Due to its mercury removal performance and recyclability, MF can be considered as a favorable adsorbent for removing elemental mercury. [ABSTRACT FROM AUTHOR]

[Display omitted] • LaFeO 3 perovskite was synthesized by sol–gel method and calcination method. • LaFeO 3 has ∼94% removal efficiency at 120 ℃. • LaFeO 3 exhibits excellent simulated flue gas resistance. • Density functional theory was applied to verify the performance of samples. LaFeO 3 perovskite was synthesized by sol–gel method and calcination method and used to remove mercury in flue gas. Three kinds of metal oxides La 2 O 3 , Fe 2 O 3 , and LaFeO 3 were evaluated. The results indicated that the performances for Hg0 removal decreased in the order of LaFeO 3 > Fe 2 O 3 > La 2 O 3. LaFeO 3 has ∼94% removal efficiency at 120 ℃. To explore the temperature response range and the influence of simulated flue gas, the performance of LaFeO 3 to remove Hg0 under O 2 , NO, SO 2 , and different temperature conditions was further examined. Furthermore, LaFeO 3 is repeat-ability. The characterization results showed that the Hg0 transition to HgO is due to the valence change of iron and the release of lattice oxygen. In addition, density functional theory (DFT) was conducted to calculate the density of states to verify the performance of the sample. This work shows that LaFeO 3 is a promising adsorbent for mercury removal from flue gas in coal-fired power plants. [ABSTRACT FROM AUTHOR]