Sulfate sampling

In the first set of comparison test runs, a 0. lOg of each sulfated sample was examined by TPR in a soak (300°C)-ramp (up to 850°C at 20°C/min.) mode, using propane at 14.2 ml/min as the reactant. In the second set of propane-TPR comparison test mns, another 0. lOg of each sulfated sample was examined by a soak (300°C)-ramp (30°C/min.)-soak (up to 530°C) mode. The reaction products such as SO and HjS released during the course of a TPR run were determined by means of mass spectrometry (Hiden Analytical, HAL-2) in MID mode, monitoring mass numbers 48 for SO fragment from SOj, and 34 for H S. 

Figure 1. Results from propane-TPR/MS tests in soak-ramp mode of sulfated samples.

The total amount of HjS released per 0.10 g of sulfated sample during the soak-ramp (up to 800°C) mode test, i.e., the integrated area up to 800°C under each plot in Figure 1, is included in Table 2. Because each sample was 3h sulfated and all thrre steps (1 - 3) are reflected in these data, it is not surprising to see that the results do not parallel with the ranking based on TGA data (also included in Table 2) which cover a 15-min period of the steps 1 and 2 combined. Nevertheless, we found these data quite useful especially when TGA data for steps 1 and 2 were not immediately available. 

Method The sample contained starch, API, Avicel, crospovidone, and sodium lauryl sulfate. Sample and references were analyzed in triplicate by NIR imaging (Spectral Dimensions, 20 coadds, spectral range 1100-2450nm). Full image size was 320 x 256 pixels or 4.1 x 3.3 mm. The NIR images were interpreted, and sample raw materials mapped, using PLS classification with five loadings (based on the reference spectra for starch, API, Avicel, crospovidone, and sodium lauryl sulfate). 

Figure 4. Scattering spectra for titania-sulfate samples before (a) and after calcination (b). To separate the curves, intensities for the samples A15, A20, A20Pt and B20 were shifted upward.

Acid mixtures containing dissolved butyl sulfate and relatively small amounts of acid were stable at temperatures from -30 to -10 C. There was no Indication of instability for samples stored several days at -20 C or several hours at -10 C. Furthermore, subsequent reactions of these stored butyl sulfates with Isobutane, as will be discussed later (9), resulted in identical products as compared to freshly prepared butyl sulfate samples. 

The sulfate samples have IR spectra that are different from those of metal sulfates the materials show absorption bands at 980-990, 1040, 1130-1150, and 1210-1230cm , which are assigned to the bidentate sulfate coordinated to metal ions. 

Name SodiuiTi dodecyl sulfate Sample preparation Potassium bromide dispersion 1 mg / 300 mg... 

A series of sulfate samples is to be analyzed by precipitation as BaS04. known that the sulfate content in these samples ranges between 20% and 55%, what minimum sample mass should be taken to ensure that a precipitate mass no smaller... 

Sulfated samples will be hereafter designated as NZSCa(Ba) -A, where N is the number of sample, A is the molar concentration of CaO or BaO in the initial composites. 

Vanadia doped sulfated Ti-pillared clays were prepared and characterized by BET, XRD, XPS, TPD-NH3 and compared with sulfated Ti-pillared clays and vanadia-doped unsulfated Ti-pillared clays. When sulfated Ti-pillared clay was doped with vanadia, the BET surface areas decrease whereas the diffraction line (001) are not significantly affected. The acidic properties of sulfated catalysts are higher than vanadia doped sulfated samples. The comparison of the activity of the catalysts in the selective catalytic reduction (SCR) of NO by ammonia in presence of oxygen show that vanadia doped sulfated Ti-pillared clay were highly active for the SCR NO. Therefore sulfated Ti-pillared clay appears as a good support for vanadia catalysts for the SCR reaction. 

The sulfated samples show a feature at 168.5 eV which was assigned to S2p of S . Catalysts which were subjected to the SCR reaction show two peaks for N1 s in the XPS spectrum, namely at 399.9 and 401.7 eV. These peaks were assigned to the ammonia chemisorbed on Lewis sites and ammonia chemisorbed on Bronsted sites, respectively. This was confirmed by means of an intensity at 1401 cm in the FTIR spectrum which was assigned to chemisorbed ammonia on Bronsted sites. 

Tablel6.1. Performance of supported oxides in the reduction of sulfated samples by propane-TPR [14],...

For the study of sulfate reduction, a large excess of H2 (Pe 13 kPa) was introduced at r.t. in the thermobalance and then the sulfated sample was heated under H2 atmosphere at increasing temperature (0.5°C.min ). 

In figure 4, we have reported the variation of the sulfated samples mass versus temperature during treatment under H2 atmosphere for Ce02 and Ce02-Zr02 compounds with or without... 

Figure 5 - IR spectra of species formed from the reoxidation at 450°C of the reduced sulfated samples a) Pt/Ce02, b) Pt/Ce02-Zr02).

It has recently been published that ceria reduction leads to Ce ions giving rise to an IR band near 2120 cm"l (14). This band appears during the H2 reduction of all sulfated samples (Fig.6) showing that ceria reduction concomitantly occurs with the sulfate reduction. 

All phosphated samples, irrespective of the preparation procedure employed, showed reduced Bronsted site densities compared with the parent, non-phosphated mixed-oxide (Table 5, column 6). In sharp contrast, Lewis site densities were always higher for the phosphate containing samples. Phosphated samples displayed a trend not too dissimilar from that obtained for sulfated samples where the gain with respect to the parent mixed oxide in Lewis sites as a function of increased phosphate loading is mirrored by a corresponding loss in Bronsted sites. This mirror effect was also apparent at the highest phosphate loading where a partial recovery of Bronsted sites was matched by a loss in Lewis sites. The consequence was that the total number of acid sites remained fairly constant across the series. 

Two dimensional TLC technique was reported for the separation of more complex mixture of catharanthus alkaloids (113) The BP (6) adopted a TLC technique to test for the presence of related alkaloids in vinblastine sulfate sample (checking the purity of the sample) ... 

Gas-volumetric and microcalorimetric measurements of 2,6-dimethylpyridine adsorption have been carried out on plain tetragonal Z1O2 and on sulfated zirconia at 423 K. The non-sulfated sample displayed an initial Q iff value of about 125 kJ mol , while sulfated samples exhibited much higher values (near 175 kJ mol ). The uptake of 2,6-dimethylpyridine can reveal, although to different extents, the presence of acidic sites that differ eifiier in nature (i.e. Lewis or Bronsted) or in acid strength [106]. 

Most authors agree that ammonia adsorption does not reveal protonic acidity on pure Ti02 (356) or Z1O2 (276). However, strong Bronsted acid sites were detected on sulfated samples (276,356,448,449). By means of successive adsorption of small doses of ammonia on sulfated titania, Desmartin-Chomel et al. (448) fbimd that initially NH3 dissociates, thus creating SOH groups which then protonate ammonia. 

Busca et al. (356) invest%ated several titania samples and reported five OH groups with bands at 3735, 3725, 3715, 3670, and 3640 cm. For a sulfated sample, an additional hydroxyl band at 3690 cm was detected. Interestingly, only the two hydroxyls with the h hest frequencies were reported to reversibly protonate ammonia. This behavior was explained by an assignment of the bands to sUica impurities. 

The v(OH) positions of the zirconia hydroxyls are slightly red-shifted after sulfation. In general, the type I hydroxyls of sulfated samples appear with reduced intensity around 3770 cm (278,497,684) and the bridging hydroxyls are detected around 3640 cm (261,276,278,335,497,684). According to Ref. (688), a band at 3630 cm indicates triply bridged OH groups in the vicinity of S20y - species. These hydroxyls demonstrate... 

In Figure 7.43, showing the sodium sulfate sample, we can observe deep cracks after several temperature cycles. 

P0) and below 550°C for sulfated samples (a4)(q4). Above 550°C the losses by retention on the crucible (at least with silica) as well as from volatilization Increase sharply (g4). 

Some ionic adsorbents show unusu ll properties (see, for example, [15, 58, 68-70]). Belyakova and co-workers [68-70] have proposed barium sulfate as a selective adsorbent They successfully used barium sulfate modified with sodium chloride for separation of some isomers of unsaturated, aromatic hydrocarbons, and oxygen- and nitrogen-containing heterocyclic compounds [68]. Barium sulfate was prepared by interaction of s< ium sulfate and barium chloride solutions of various concentration present in equimolar proportions. The specific surface areas varied from 2.5 to 8 m /g. To investigate this ionic adsorbent, glass Ccipillary columns (1 mm i.d.) were packed with barium sulfate particles (0.16-0.20 mm). The maximum value of separation selectivity for all xylene isomers was observed on barium sulfate samples modified with 15% sodium chloride solution [69]. According to electron spectroscopy for chemical analysis these samples contained on the surface about 2% of... 

Addition of 1000 ppm propane to the methane feed decreased the temperature required to achieve 50% conversion from 560 to 380 °C over a pre-sulfated catalyst [357]. Combustion of the 1000 ppm propane occurred by 150°C over the platinum catalyst. A 50% propane conversion was achieved for the sulfur-free catalyst at 260 °C, while only 210°C was required for the pre-sulfated sample. However, the weight hourly space velocity was rather low at 30 L (hgcat) for the experiments of Corro et al. [357]. 

Suspension Preparation. The preparation for the activator-fi suspension After drying, chitosan sulfate samples were dispersed in a certain amoxmt of silicone oil and ball-milled imtil microscopic examination indicated a mean particle size of 10 pm and the absence of particles > 20 pm. Particles were irregular in shape but without any tendency to anisometry. The silicone oil used is a colorless oil with the following physical properties density 0.97 g/cm, viscosity 100 mPa s at 20 C, dielectric constant 2.8, and boiling temperature 300 C. There was little tendency for these dispersions to separate in the short term, and such dispersions that had separated after lengthy standing readily redispersed on agitation. 

The preparation for the activator-containing suspension The chitosan sulfate samples were immersed into the glycerin-methanol solution for 72 hours, to make sure the samples adsorb a certain amount of glycerin. The fraction of the adsorbed glycerin is determined by the weight method, and the glycerin content is 5wt%. After the removal of methanol, the chitosan sulfate suspension was made with the same procedures as the above-mentioned. 

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