Characterization nitrogen adsorption-desorption

Catalysts Characterization Catalysts were characterized by nitrogen adsorption-desorption isotherms, XRD, XPS, TEM, and FT-IR. The concentration and the strength of the acid sites were determined using a combination of NHs-chemisorption and FTIR. Detailed procedures are given elsewhere [18, 19]. 

Characterization. The high resolution TEM images were obtained on a JEOL 2010 electron microscope with an acceleration voltage of 200 kV. Measurement of nitrogen adsorption-desorption isotherms was performed on a Micromeritics ASAP... 

The new composite (SC-155) and some of its precursors and derivatives were characterized by LOI (loss on ignition), XRD ( X ray diffraction), 1R (infrared spectra), BET specific surface area, nitrogen adsorption desorption isotherms, pore size distribution (mercury porosimetry), dynamic methylene blue adsorption and SEM (Scanning Electron... 

The catalyst powder was characterized by atomic absorption (chemical composition), X-ray powder diffraction (structure identification and degree of crystallinity) and nitrogen adsorption/desorption. For the latter method, an automatic Micromeretics ASAP 2000 apparatus was used, which also allowed the determination of the pore size distribution in the mesopore and macropore region (2 nm to 300 nm). 

Mesoporous melamine-formaldehyde and phenolic-formaldehyde resins were synthesized in the process of polymerization in the presence of fumed silica as an inorganic template. The surface and structural characteristics of the obtained sorbents were investigated using XPS technique and sorption from gas phase. The parameters characterizing porous structure of the synthesized resins in a dry state were determined from nitrogen adsorption/desorption isotherms. The sorption processes of benzene and water vapor accompanied by simultaneous swelling of both polymers were also studied. 

There are other techniques that can be used to characterize the thin film. For powdered materials, nitrogen adsorption-desorption isotherms are typically used to determine the pore volume and surface area. However, this technique is rather difficult for films, as the... 

The materials were characterized by XRD (Rigaku Rint - 2400, Cu-Ka radiation, 40 kV, 40 mA), UV-Vis (Photal Otsuka Electronics, MC-2530 UVA IS light source), and nitrogen adsorption/desorption, BET surface area measurements (Micromeritics ASAP 2010 apparatus). 

The characterisation of the colloids both in the free and in the embedded state was first performed using transmission electron microscopy (TEM), energy dispersive X-ray analysis (EDX), and atomic absorption spectroscopy (AAS). In addition, nitrogen adsorption-desorption curves at 77 K, H2-chemisorption measurements, solid state Si-NMR, XRD, SAXS, XPS, MAS-NMR, NH3-FTIR, and Au Mossbauer spectroscopy were applied. For the embedded triflates, the catalysts were characterized by nitrogen adsorption-desorption isotherms at 77K, TG-DTA, H, C, and Si solid state MAS-NMR, XRD, TEM, SEM, XPS and, FTIR after adsorption of NH3. 

Sample Characterization. The BET nitrogen adsorption-desorption isotherms were performed in an ASAP 2000 instrument using N2 at -195 °C. The microporous area was estimated using the correlation of t-Harkings Jura (T-plot method). 

Nitrogen adsorption-desorption isotherms of the samples with different Co/Si molar ratio (Fig. 6) are characterized by a very steep increase at the relative pressure P/Po of around 0.38, indicating the homogeneity of our bimetallic incorporated mesoporous molecular sieves. 

Measurement of pore size distribution has now become an essential feature of particle characterization. Questions of pore didusional resistance, pore mouth poisoning, and deactivation control can only be answered if accurate descriptions of both size and shape are available over the whole pore size range. Historically, macroporcs have been measured with mercury porosimeters and mesopores with nitrogen adsorption-desorption isotherms. 

FIGURE 1.254 Pore size distributions of unmodified and modified nanosilica A-380 (Table 1. 3) calculated on the basis of the nitrogen adsorption/desorption isotherms using DFT method with the model of pores as voids between spherical particles and NMR cryoporometry with IGT equation. (Adapted from/ Colloid Interface ScL, 308, Gun ko, V.M., Turov, V.V., Zarko, V.I. et al., Comparative characterization of polymethylsiloxane hydrogel and silylated fumed silica and silica gel, 142-156,2007h. Copyright 2007, with permission from Elsevier.)... 

Consequently, LiChrolut EN is a nano/mesoporous adsorbent. This adsorbent is characterized by pores of a more complex shape than carbon adsorbents (even produced from natural raw materials) because cross-linked polymer chains form a disordered tangle structure. Therefore, the nitrogen adsorption/desorption isotherm for this adsorbent has a large and practically open hysteresis loop (Figure 5.26). 

In this work the merits of the use of a natural fibrous mineral, sepiolite, as a binder to produce titania based monoliths of high mechanical strength and abrasion resistance is discussed. The monoliths of square channels were conformed with an initial 7.5 channels cm and 1 mm wall thickness. TTie textural characterization was made by mercury intrusion porosimetry (MIP), nitrogen adsorption/desorption (BET), and X-ray diffraction (XRD). The mechanical resistance, dimensional changes and weight losses al each stage of heat treatment were also determined. The thermal expansion coefficients (TEC) of the monoliths were determined between 200 and 400 C, since in practice the usual working temperature of DENOX catalysts lies between 250°-350 C. 

The effect of compression on the structure of MCM-41 with the template within the pores was examined by N2 adsorption. Fig. 6 shows the N2 adsorption/desorption isotherms for the as-synthesized MCM-41 before and after compression. The nitrogen adsorption/desorption isotherm for as-synthesized sample and samples after hydrostatic pressure experiment exhibit over the relative pressine p/po = 0.9 hysteresis loop which is characteristic of the c illary condensation between silica particles. Some parameters characterizing porosity of the investigated samples are collected in Table 1. Two samples with the template do not exhibit porosity of MCM-41 silica. Only for MCM-41 after compression in argon the specific surface area and pore volume are little higher in comparison to the as-synthesized sample. 

---