Excellent Catalytic Performance of Ce–MOF with Abundant Oxygen Vacancies Supported Noble Metal Pt in the Oxidation of Toluene

Metal organic framework (MOF) is a type of porous organic material. In this work, three catalysts loaded with noble metal Pt were prepared by NaBH4 reduction method with three different morphologies of Ce–MOF as carriers. Their physicochemical properties were characterized by XRD, Raman, FTIR, N2 adsorption, SEM, XPS, and TGA. The catalytic performances of different catalysts were evaluated via toluene oxidation and CO2 selectivity. Rod–shaped Pt/MOF–BTC exhibited best catalytic performance compared to Pt/MOF–808 and Pt/UiO–66, its T50 and T90 were 140 °C and 149 °C, respectively. After deducting the effect of specific surface, Pt/MOF–BTC still had the lowest apparent activation energy (62.8 kJ·mol−1), which is due to the abundant atomic Pt and oxygen vacancy content on its surface. After the reaction, the structure of Pt/MOF–BTC may become amorphous according to XRD results. Furthermore, the presence of amorphous structure had no effect on the catalytic activity of the catalyst. In the stability test of Pt/MOF–BTC to toluene oxidation, both toluene conversion and CO2 selectivity remained at 100%, and remained stable for 11 h. Moreover, Pt/MOF–BTC also had better resistance to high weight hourly space velocity (WHSV) or water resistance. The catalyst maintained high catalytic activity for 3 times reusability. This study provides valuable experience for the future work of MOF in the field of VOC catalytic oxidation

Excellent Catalytic Performance of Ce–MOF with Abundant Oxygen Vacancies Supported Noble Metal Pt in the Oxidation of Toluene

Metal organic framework (MOF) is a type of porous organic material. In this work, three catalysts loaded with noble metal Pt were prepared by NaBH4 reduction method with three different morphologies of Ce–MOF as carriers. Their physicochemical properties were characterized by XRD, Raman, FTIR, N2 adsorption, SEM, XPS, and TGA. The catalytic performances of different catalysts were evaluated via toluene oxidation and CO2 selectivity. Rod–shaped Pt/MOF–BTC exhibited best catalytic performance compared to Pt/MOF–808 and Pt/UiO–66, its T50 and T90 were 140 °C and 149 °C, respectively. After deducting the effect of specific surface, Pt/MOF–BTC still had the lowest apparent activation energy (62.8 kJ·mol−1), which is due to the abundant atomic Pt and oxygen vacancy content on its surface. After the reaction, the structure of Pt/MOF–BTC may become amorphous according to XRD results. Furthermore, the presence of amorphous structure had no effect on the catalytic activity of the catalyst. In the stability test of Pt/MOF–BTC to toluene oxidation, both toluene conversion and CO2 selectivity remained at 100%, and remained stable for 11 h. Moreover, Pt/MOF–BTC also had better resistance to high weight hourly space velocity (WHSV) or water resistance. The catalyst maintained high catalytic activity for 3 times reusability. This study provides valuable experience for the future work of MOF in the field of VOC catalytic oxidation

Selective capture of Tl2O from flue gas with formation of p–n junction on V2O5–WO3/TiO2 catalyst under working conditions

Thallium (Tl) compounds, highly toxic to biology, are usually released into flue gas during fossil/minerals combustion, and further distributed in water and soil. In this work, we fundamentally investigated the capture of gaseous Tl2O by industrial V2O5–WO3/TiO2 catalyst under working condition in Tl-containing flue gas. Experimental and theoretical results indicated that the Tl2O has significant electron-feeding capacity and easily donate electron to unoccupied orbitals of TiO2, leading to dismutation of Ti 2p and inartificial formation of p–n junction on TiO2 surface, which prompted Tl2O selectively interacted with TiO2 in flue gas. Herein, we proposed and verified an effective way to capture gaseous Tl2O, which offered almost the best choice to eliminate Tl emission from flue gas and expanded the function of the TiO2-based catalyst. The formation of p–n junction on commercial V2O5–WO3/TiO2 catalyst under working condition was revealed for the first time, which can be a valuable reference for both heterocatalysis and electro/photocatalysis

Synergetic analysis between polyvinyl chloride (PVC) and coal in chemical looping combustion (CLC)

This effort is to investigate three different Cu-based oxygen carriers (OCs) with polyvinyl chloride (PVC) and coal in chemical-looping combustion (CLC). The combustion process and synergetic analysis of PVC with coal were evaluated. There were four stages in the reaction of OCs with PVC, which HCl released from PVC could react with OCs at about 200–400 °C. CuO and CuO modified by limestone showed better immobilization of chlorine while CuO modified by iron ore and chrysolite inhibited the reaction of HCl with CuO. PVC char combustion temperature started at about 500 °C which were lower than that of coal char. The combustion efficiency of PVC CLC was all above 92%, except using Cu-Fe as OC which was about 88%. The presence of ZD in PVC showed positive effect on every stage. The addition of coal inhibited the reaction of HCl with CuO. The presence of PVC in ZD reduced the temperature of coal char and the addition of ZD in PVC increased the reaction rate. The synergistic effect was obvious between the PVC and coal blends which is beneficial for the complete combustion in solid fuel CL

Study on the Accuracy of Fracture Criteria in Predicting Fracture Characteristics of Granite with Different Occurrence Depths

The fracture network of a deep geothermal reservoir forms the place for heat exchange between injected fluid and rock mass with high temperature. The fracture resistance ability of reservoir rocks will affect the formation of fracture-network structure, heat exchange and transmission characteristics, and reservoir mechanical stability. However, there are few reports on the fracture toughness and trajectory prediction of geothermal reservoirs with different depths. In this paper, the modified maximum tangential stress criterion (MMTS) is analyzed. The results show that the experimental data are significantly different from the theoretical estimate of MMTS under the influence of different occurrence depths. It is found that the fracture process zone (FPZ) seriously affects the accuracy of predicting fracture initiation angle and mixed-mode (I+II) fracture toughness by MMTS. The FPZ value, considering the influence of different occurrence depths, is modified, and the accuracy of MMTS in predicting the fracture mechanical characteristics of granite is improved. In addition, the mechanical test results show that the Brazilian splitting strength (σt) of granite fluctuates increase with the increase in temperature. With the increase in deviatoric stress, the Brazilian splitting strength and the Brazilian splitting modulus of rock show a trend of first increasing, then decreasing, and then increasing