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Na 4 Mn 9 O 18 whiskers were prepared on the wall of cordierite honeycomb ceramics using the molten salt synthesis, and Na 4 Mn 9 O 18 whiskers were grew on channel surface of cordierite honeycomb ceramics to form hierarchical microstructure for catalytic combustion of soot. Scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), and X-ray diffraction (XRD) were used to characterize the structural morphology and phase compositions. Na 4 Mn 9 O 18 whiskers with aspect ratio of 24.4 measured by statistics. It was found that the loading rate of the monolithic catalyst reaches 3.588% while the binding rate after sonication almost no change. Whiskers are tightly combined with the cordierite ceramic substrate by the binding strength experiments and EDS analysis. The oxygen temperature-programmed desorption (O 2 -TPD) measurements were performed to investigate the O 2 adsorption property. The catalytic performance of the samples were examined by semi-quantitative thermal gravimetric analysis (TG-DTG) and temperature-programmed oxidation (TPO). The catalyst performance study demonstrates that Na 4 Mn 9 O 18 whiskers decrease the soot combustion temperature apparently. Experiments show the characteristic temperature could be reduced by increasing the catalyst loading. The Na 4 Mn 9 O 18 decreased the ignition temperature of soot particles oxidation, and the cycle stability experiment confirmed that the sample (0h-m-k) has good structural stability and stable catalytic performance. The coarseness of the interface increased because Na 4 Mn 9 O 18 whiskers grew on the cordierite substrate, and the trapping ability improved. Na 4 Mn 9 O 18 is an important type of catalyst which is rarely studied in catalytic oxidation of soot. This catalyst displays good activity and stability in the soot catalytic oxidation. This unique microstructure has potential application in the DPF field. [ABSTRACT FROM AUTHOR]

Mullite whiskers were prepared on the wall of cordierite honeycomb ceramics using the gas-phase growth method. Subsequently, Co/Ce 0.75 Zr 0.25 O 2 catalyst was loaded on the mullite whiskers to form hierarchical microstructure by the sol-gel technology for catalytic combustion of soot. Scanning electron microscopy, energy dispersive X-ray spectroscopy, Fourier transform-infrared spectroscopy, X-ray diffraction and Transmission electron microscopy were used to characterize the structural morphology and phase compositions. The filtration capability can be improved by mullite whiskers growth on the wall of cordierite honeycomb ceramics, and the microstructural feature is similar to the pseudostratified ciliated epithelium on the tracheal cavity surface (one section of human respiratory system). The Co/Ce 0.75 Zr 0.25 O 2 catalyst decreased the ignition temperature of soot particles oxidation, and the cycle stability experiment confirmed that Co/CZ@M/C sample has good structural stability and stable catalytic performance. The high-efficiency filtration and the low-temperature catalytic oxidation of soot particles are combined with the hierarchical microstructure of Co/CZ@M/C, which has potential application in the diesel particulate filter (DPF) field. [ABSTRACT FROM AUTHOR]

In this paper, potassium titanate whiskers was prepared via the Molten salt synthesis on the surface of cordierite ceramics for the regeneration of diesel particulate filters (DPFs). SEM, EDS, XRD, FT-IR, TG-DSC and TPO were carried out to characterize the morphology, microstructure, growth mechanism and catalytic performance of the samples. Potassium titanate whiskers with diameter (100–500 nm) and length (about 3 μm) is tightly combined with the cordierite ceramic substrate. The catalyst performance investigation demonstrates that potassium titanate whiskers decrease the soot combustion temperature apparently. The soot combustion process was studied by thermal analysis tests, and the activation energy of the combustion reaction can be calculated using Freeman-Carroll method. The carbon oxidation activation energy is 14.009 kcal/mol, and the activation energy for the catalytic reaction with potassium titanate whiskers is 6.287 kcal/mol, it can be illustrated that potassium titanate whiskers/cordierite catalyst possess excellence performance for carbon catalytic combustion. The coarseness of the interface increased because potassium titanate whiskers grew on the cordierite substrate, and the trapping ability could improve. This unique microstructure has potential application in the DPF field. [Display omitted] [ABSTRACT FROM AUTHOR]

Magnesium borate whiskers were used to prepare a hierarchical microstructure on cordierite ceramic substrate through the precipitation-molten salt method. The La 2-X Ce X Zr 2 O 7 catalyst was then loaded onto the magnesium borate whiskers to form the hierarchical microstructure. The Ce-doped catalysts exhibited a significant improvement in the catalytic activity of soot combustion compared to the La 2 Zr 2 O 7 catalyst. The study employed various techniques to characterize the structural morphology and phase composition, including scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), Fourier transform-infrared spectroscopy (FT-IR), and X-ray diffraction (XRD). The growth of Magnesium borate whiskers (Mg 2 B 2 O 5) with diameters of 100–200 nm and lengths of 2–5 μm were grown and tightly bonded to the cordierite ceramic substrate to mimic the structure of human respiratory system cilia. This could improve the filtration efficiency of soot in car exhaust. BET analysis showed that the specific surface area of cordierite increased from 0.684 m2/g to 1.363 m2/g after whisker growth. The study confirmed that the whiskers were firmly attached to the cordierite ceramic substrate, as demonstrated by the binding strength experiments. The addition of Ce metal has been found to significantly enhance soot combustion due to the presence of more active oxygen species and superior mobility of lattice oxygen species with more oxygen vacancies. The catalyst's intrinsic redox property was characterized using X-ray photoelectron spectroscopy (XPS) and H 2 temperature-programmed reduction (H 2 -TPR). The semi-quantitative thermogravimetric analysis (TG-DTG) and the temperature-programmed oxidation (TPO) of catalysts showed that Z-La 1.9 Ce 0 · 1 Zr 2 O 7 exhibited the highest catalytic activity for soot combustion, with an ignition temperature of 268 °C, a peak temperature of 418 °C, and a temperature of 90 % soot conversion of 464 °C. Furthermore, cyclic stability experiments demonstrate that the Z-La 1.9 Ce 0 · 1 Zr 2 O 7 catalyst exhibits excellent structural stability and consistent catalytic performance. This distinctive microstructure holds great potential for applications in the field of DPF. [ABSTRACT FROM AUTHOR]

Particulate matter (PM) generated by residential wood combustion is a major environmental concern in Europe. This study focuses on the influence of potassium chloride (KCl) on fine particle emissions from a modern wood stove. Wood logs with and without KCl impregnation were subjected to batch combustion and emission measurements. A bi-modal particle number-size distribution characterized by a nucleation mode and an accumulation mode was identified for all types of wood fuel. However, in the presence of KCl, a lower number emission of ultrafine particles and a higher number emission of larger particles (size ∼200–500 nm) were observed. In addition, the emission factor of condensed organic compounds (COC) increased with increasing KCl content, from 0.16 g/kg dry wood for normal wood (NW) to 0.48 g/kg dry wood for wood impregnated with the 2 mol/L KCl solution (HKW), most likely due to the facilitated heterogeneous condensation of semi-volatile hydrocarbons on pre-existing ash particles. In addition, the emission factor of soot particles also increased slightly when the KCl content was high, from 1.47 g/kg dry wood for NW to 2.23 g/kg dry wood for HKW. • PM emissions from the combustion of KCl-impregnated wood in a domestic stove were characterized. • The emission of accumulation mode particles from the wood stove increased in the presence of KCl. • The organic carbonaceous emissions from the wood stove increased with increasing KCl content in the fuel. • A high KCl content in the fuel slightly promoted the soot emissions from the wood stove. [ABSTRACT FROM AUTHOR]

The influence of potassium chloride (KCl) and potassium hydroxide (KOH) on the formation of benzene and soot in fuel-rich oxidation of methane was investigated experimentally using a flow reactor at atmospheric pressure and temperatures ranging from 1273 to 1673 K. The methane inlet concentration was kept constant at 2 vol.% (nitrogen balance), while the C/O ratio was 2 or 5. The potassium salt was fed into the main gas flow at a comparatively high concentration of around 1000 ppm. The onset of formation of acetylene and benzene was around 1373 K. The addition of both potassium salts was found to promote formation of acetylene and benzene at temperatures below 1523 K. This effect was most pronounced at a high C/O ratio of 5 and in the presence of KOH, but diminished at temperatures above 1523 K. A detailed chemical kinetic model was used to interpret the experimental results and was found to be able to partially reproduce the promoting effect of KOH. According to the model, the addition of KOH facilitates the buildup of OH radicals through the rate controlling reaction KOH + M ⇌ K + OH + M. The promotion of the radical pool favors the formation of active intermediates including methyl and vinyl radicals, both of which play an important role in the major benzene formation pathways under the conditions investigated. Particle analysis using SMPS showed a net increase in the volume concentration of soot and a shift of the particle size distribution towards larger diameters in the presence of KOH, but no quantitative difference was observed for the mass of carbonaceous materials collected on filters. [ABSTRACT FROM AUTHOR]