Asap 2010 analyzer

The surface morphology of samples was observed using a field emission scanning electron microscope (FESEM, JSM–6701 F, JEOL, Ltd. Japan) after the samples were fixed on copper stubs and coated with gold film. The XRD patterns were collected using an X’Pert PRO diffractometer equipped with a Cu Kα radiation source (40 kV, 40 mA). TEM was observed using a JEM-1200 EX/S transmission electron microscope (TEM) (JEOL, Tokyo, Japan). FTIR spectra were measured on a Thermo Nicolet NEXUS TM spectrophotometer in the range of 4000–400 cm^–1 using a KBr platelet. The specific surface area was measured on ASAP 2010 analyzer (Micromeritics, USA) at 77 K by determining the N₂ adsorption-desorption isotherms. The values of specific surface area (S_BET) were calculated by the BET equation. The total pore volumes (V_total) were obtained from the volume of liquid N₂ held at the relative pressure P/P₀ = 0.95. The micropore volume (V_micro) was estimated by the t-plot method. The chemical composition was determined using a Minipal 4 X-ray fluorescence spectrometer (PANalytical, Netherland). Zeta potentials were measured on a Malvern Zetasizer Nano system with irradiation from a 633 nm He-Ne laser (ZEN3600). Before measurement, samples were dispersed in deionized water by a high-speed stirring to form a uniform 0.5% (w/v) aqueous dispersion.

The three Al₂O₃ particles were purchased as powders from different manufacturers. They are named in the following as Alu1 (AEROXIDE^® Alu C, Evonik Degussa GmbH), Alu2 (TAIMICRON^®, TM-DAR, Taimei Chemicals Co., LTD.), and Alu3 (NABALOX^®, NO-625-10, Nabaltec AG). The morphology of the particle powders was investigated by scanning electron microscopy (SEM, Zeiss Leo 982 FEG, Carl Zeiss SMT AG). The N₂-BET-specific surface area was obtained by gas adsorption measurement according to the Brunauer-Emmet-Teller method (ASAP 2010 Analyzer, Micromeritics GmbH), and the crystalline structure of the powders was determined by X-ray diffraction (XRD7, Seifert-FPM). The powder density was determined using helium pycnometry (Penta Pycnometer, Quantachrome GmbH & Co. KG). Theoretical primary particle size (x_BET) was calculated on the basis of the BET and density values obtained.

The surface and morphology were visualized using electron microscopy facility (JEOL FE-2010 high-resolution microscope operated at 200 kV). The Raman spectra were recorded with a Renishaw inVia unit using the Ar ion laser with an excitation wavelength of 514.5 nm. X-ray photoelectron spectroscopy (XPS) analysis was studied using a VG Scientific ESCALAB 220 iXL spectrometer with an Al Kα (hv = 1486.69 eV) X-ray source. Nitrogen adsorption and desorption isotherms were measured at 77 K using Micromeritics ASAP 2010 Analyzer (USA) to obtain the Brunauer-Emmett-Teller (BET) surface area and pore size distribution.

All the aforementioned CeO₂ morphologies were characterized by means of X-ray diffraction (PW1710 Philips diffractometer, Amsterdam, The Netherlands, equipped with a Cu Kα radiation monochromator to check that the cerium oxide crystalline structure had been achieved and to estimate the average crystallite size via the Debye-Scherrer technique. A field emission scanning electron microscope (FESEM, Leo 50/50 VP Gemini column) was used to analyze the morphology of the CeO₂ structures and to correlate it to its activity towards soot oxidation. A BET analysis (Micromeritics ASAP 2010 analyzer, Norcross, GA, USA) was conducted to evaluate the specific surface area of the catalysts and to perform a porosimetry analysis of the prepared catalysts. An ageing thermal treatment was performed for all three catalysts at 600°C for 5 h in order to have a better understanding of their reliability and performances under stressed conditions, namely when exposed to high temperatures for a certain period.

OM-Co₃O₄ was synthesized using nanocasting route with KIT-6 as hard template, and the procedure was conducted as described before.^{16 (link)} For the preparation of Co₃O₄-composite spinels, 1.0 g OM-Co₃O₄ was dispersed in 2.5 mL ethanol of Fe(NO₃)₃·9H₂O, Mn(NO₃)₂·4H₂O, Cu(NO₃)₂·3H₂O and Ni(NO₃)₂·6H₂O, respectively, and Co/M molar ratio was controlled at 3. After magnetic stirring for 1 h, the mixture was dried overnight at 60 °C and then calcined at 450 °C for 5 h (the heating rate was set at 2 °C min⁻¹). Finally, the obtained composite spinels were referenced as Co₃O₄–CoM₂O₄ (M = Fe, Mn) and Co₃O₄–MCo₂O₄ (M = Cu, Ni) which depended on the oxidation state of dopant.
The crystal structures of catalysts were characterized by X'Pert PRO diffractometer (PANalytical, Holland) with Cu Kα radiation. The morphologies and structures of Co₃O₄-composite spinels were observed using transmission electron microscopy (TEM) (Philips, Holland). N₂ adsorption and desorption isotherms were measured using ASAP 2010 analyzer (Micromeritics, USA) at liquid nitrogen temperature (−196 °C). The pH at point of zero charge (pH_pzc) was determined by Zetasizer Nano analyzer (Malvern, UK).