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The plane exposure of support vitally affects the catalytic performance of the catalyst. In this work, CeO2 nanorods ((1 1 0) plane exposure), nano-octahedrons ((1 1 1) plane exposure) and nano-cubes ((1 0 0) plane exposure) were prepared as the supports of Pt/CeO2 samples to investigate the effect of CeO2 plane exposure on total toluene oxidation. Characterizations reveal that the (1 1 0) plane of CeO2 is more helpful to the dispersion of Pt species, followed by (1 1 1) face. The improved dispersion of Pt species can enhance the metal-supports interaction, which promotes the electron transfer of CeO2 carrier to Pt nanoparticles and the adsorption-activation of O2, thereby facilitating the total oxidation of toluene via the Langmuir–Hinshelwood (L-H) mechanism. Therefore, Pt/CeO2-r (nanorods) sample expresses the most excellent catalytic performance of toluene oxidation. Finally, the procedure of toluene total oxidation was studied by in-situ DRIFT. We expect that this work can contribute to the development of an effective sample for the decomposition of volatile organic compounds (VOCs).

In this study, the acid sites on the surface of the catalyst were quantitatively analyzed by pyridine adsorption infrared spectroscopy. When the molar ratio of V/P is 5, the molar ratio of HCl/V is 3, and the calcination temperature is 450 °C, the selective catalytic reduction effect of NO over VPO/TiO2 catalyst is the best (up to 99% at 200 °C), and the acidity of the catalyst is the highest, which is 5600 μmol·g−1. The results showed that the SCR activity of VPO/TiO2 catalyst increased with the increase of acidity at low temperature. Furthermore, the correlation between the denitration activity and the surface acid level was established by means of data fitting. The results showed that the low temperature denitrification activities of all VPO/TiO2 catalysts were positively correlated with the content of weak Lewis acid center (correlation coefficient > 0.9). In conclusion, this study provides a new method for analyzing the structure–activity relationship of the catalyst and provides some theoretical basis for the design of NH3-SCR catalyst.

A high moisture content in the flue gas of iron and steel sintering process causes the issue of filter material pasting, which leads to a decrease in the filtration effect and service life of the filter material. Surface modification of the filter materials is a useful strategy for their hydrophobicity enhancement. Therefore, the Sol–gel method was employed to modify the polyethylene glycol terephthalate (PET) filter with tetraethyl orthosilicate(TEOS) as precursor and perfluorodecyl triethoxysilane (PFDTES) as modifier. Field emission scanning electron microscope (FESEM), Fourier transform infrared spectrometer (FT-IR), and contact angle tester were used to characterize the PET filter materials before and after modification, and exhaustive filter efficiency was evaluated by the comprehensive performance test machine. The particle size and distribution of SiO2 nanoparticles were analyzed using a nanometer particle size analyzer, the effects of TEOS/PFDTES loading on the hydrophobic performance and filtration performance of the filter material have been discussed. Based on the results of these studies, superhydrophobic stability of the filter material was evaluated. The results show that the microscopic pore structure of PET filter materials was retained after modification. TEOS modified PET (T-PET) filter materials were completely wetted with static contact angle (WCA) of 0°. The surface energy of PFDTES modified PET (F-PET) filter materials was reduced, the WCA was 144.6 ± 1.6° and WSA was 7.6 ± 4.5°. For TEOS/PFDTES co-modified PET (TF-PET), the SiO2 nanoparticles was modified by the long fluorine chain -CH2CH2(CF2)7CF3 groups, endowing TF-PET with superhydrophobic property. With the increasing of TEOS loading, TF-PET fiber presented significant enhancement of roughness, while average particle size of SiO2 nanoparticles on the fiber surface gradually decreased. The particle size distribution first increased sharply, and then, slowly decreased when TEOS addition was enhanced. TF-PET filter material possessed WCA of 163.2 ± 2.3°, while when TEOS: PFDTES mass ratio was 2.5:2, WSA was 6.2 ± 1.9° with filtration efficiency (0.3 μm) of 68.61%.

Mine dust removing systems mostly use wet dust collectors at present, according to the latest national emission standard, it is difficult to meet the emission requirements. Although the traditional bag filter can meet emission requirements, the water content of the particles is high in the mine, and the filter bag usually has the phenomenon of condensation, sticking to bags, and dust cleaning difficulties during use. Therefore, the experimental system was designed for low-pressure pulse dust cleaning of plate-frame microporous membrane dust collector, and the influence of different cleaning parameters on cleaning performance was studied, including the number of injection holes, injection distance, injection pressure and pulse injection time. And the optimal working conditions were selected to test the effect of the filter plate under the condition of powder attachment. The results show that the number of injection holes, injection distance and injection pressure have effects on the peak pressure, and the effect of pulse injection time on the peak pressure is implicit. The optimal conditions for the pulse cleaning operation parameters of plate-frame filter is 10 × Φ 5 injection hole, the injection distance of 20 mm, the injection pressure of 0.30 MPa, and the pulse injection time of 100 ms. On this basis, the cleaning effect of the filter plate with powder test is better, and the dust stripping rate φ was 92.9%, which is higher than 81%. The optimized plate-frame type dust collector has a better cleaning effect, indicating that the feasibility and applicability of pulse dust cleaning in plate-frame type dust collector have been improved.

The micro-scale model of fibrous media was simulated to obtain viscous resistance in clean state, which was provided to the CFD porous media. A macro-scale model for predicting the pressure drop during dust loading was established based on the Euler-Lagrangian method by implementing the UDF in ANSYS-Fluent. The trapping mechanism programs were developed to realize different distribution forms of particles in the porous media. The macro-empirical model was used to calibrate the macro-scale model under different SVFs. The 592*592*292-4 V–F9 filter was simplified to CFD porous media and the numerical simulation was carried out during dust loading. The results show that the pressure drop shows different growth trends under different trapping mechanism programs. Very good agreement was found between the experimental and simulated pressure drop during dust loading. Thus, the macro-scale model broadens the way of studying the pressure drop of fibrous media in depth filtration.

Selective catalytic reduction（SCR） technology is the key technology of flue gas denitration. SCR reactors are the systems contributing to pollution-free emission if they function properly. In order to study SCR denitration chemical reaction simulation and optimize the denitration effect, the CFD analysis of SCR reactor was carried out. The realizable k-ϵ turbulence model, component transport model and chemical reaction model were used to simulate the SCR denitration reactor. Based on the response surface methodology (RSM), the effects of three factors on the denitration efficiency were studied, including catalyst inlet gas velocity, reaction temperature and NH3/NO molar ratio. The quadratic multinomial regression model of three factors affecting the denitration efficiency was established. In addition, the structure of hot air duct and guiding plate were optimized based on the non-uniform inlet temperature. The results showed that: three factors had a significant impact on the denitration efficiency, and the interaction of catalyst inlet gas velocity and reaction temperature is the most significant; the structure optimization of hot air duct and guiding plate can improve the denitration efficiency and reduce outlet NO concentration relative standard deviation, and avoid catalyst abrasion. In this paper, a suitable numerical simulation model is proposed for SCR denitration reaction, and the consideration of non-uniform inlet temperature and the proposition about taking relative standard deviation of NO concentration at the outlet as an optimization index contribute to a more practical and more reasonable structure optimization.

3D micro-scale model of fibrous media with controllable structural parameters (such as fiber diameter, solid volume fraction and cell configuration) was constructed by using Voronoi algorithm in this study. Compared with the fibrous media model having layer-structured topology, the Voronoi-based model can well characterize the penetration behavior between fibers and layer connections. The gas–solid flow characteristics in fibrous media under different structural and operating parameters were examined numerically and semi-analytically. The results show that the pressure drop of fibrous media between numerical results and experimental values in literature is not always consistent. A new pressure drop correlation for fibrous media is proposed. Additionally, numerical results of the filtration efficiency show similar tendencies to the results that are calculated by the semi-analytical model. For submicron particles, the Stokes-Cunningham drag law combined with Saffman’s lift force and Brownian force can accurately predict the capture action dominated by the combination of diffusion and inertia. The deviation of filtration efficiencies between numerical results and theoretical predictions increases with increase of the Peclet number. For micron particles, the semi-analytical model-determined filtration efficiency is generally higher than numerical results which adopting the spherical drag law and considering the gravity effect. Moreover, a threshold value of the Stokes number that determines the deviation between numerical and semi-analytical approaches is presented. When the Stokes number is greater than the threshold, a relatively small deviation can be achieved. It is concluded that the new pressure drop correlation can provide guidance for macro-scale model to study the filtration performance. As well, the correlation calculating of filtration efficiency between numerical simulation and semi-analytical model is obtained by using the Peclet number and the Stokes number as criteria.

In order to obtain the comprehensive filtration information, such as the deposition morphology of particles, evolutions of the instantaneous pressure drop and efficiency, 3-D mimic models of fibrous media had been established using a stochastic algorithm and computational fluid dynamics (CFD) - discrete element method (DEM) model was adopted to simulate the gas-solid flow characteristics in fibrous media exposed to particle loading in this work. Meanwhile, the simulation results had been validated by the macro-empirical model proposed in the previous literature. In addition, the influence of various parameters including porosity, face velocity and particle size on the filtration performance of fibrous media had also been investigated. It is concluded that simulation results of the CFD–DEM model are good agreement with predictive values of the macro-empirical model. Moreover, the porosity of fibrous media, face velocity and particle size have an important effect on the filtration performance of the fibrous media.

Numerical studies were conducted for different inlet particle concentrations of a cyclone. The simplified Eulerian model—Algebraic Slip Mixture Model (ASMM) was used for different inlet particle concentrations. With the increase of the inlet particle concentration, particle–particle interaction becomes important. ASMM can take into account this effect in this condition. The present work considered the particle of different size as different phase, and obtained a collision coefficient by experiment when considering the interaction between particles. The advantage of the ASMM is that this model can save a lot of calculating time comparing with the full Eulerian model. However, higher inlet particle concentration will result in the agglomeration between particles deduced by some mechanisms. In point of this fact, the calculated results based on ASMM have some differences comparing with the practical ones. Therefore, this model still has some discrepancies which plead for further improvement. In spite of this fact, this model can be used to analyze the effect of the inlet particle concentration on the separation characteristics of the cyclone qualitatively in practical applications.