Quartz wool

Thermal and Photochemical Reactions. Unsubstituted ethyleneimine has astonishing thermal stabihty. The reaction of ethyleneimine diluted with argon proceeds to give a mixture of unidentified compounds only at temperatures above 400°C (339). In a flow pyrolysis system under pressures of <1.33 kPa (<10 mm Hg) on quartz wool, isomerization to give /V-methylenemethylamine and ethylideneimine was observed only ia the temperature range 510—535°C. Higher temperatures result ia fragmentation (340). 

Cadmium [7440-43-9] M 112.4, m 321.1°, b 767°. Oxide has been removed by filtering the molten metal, under vacuum through quartz wool. 

The carbon number distribution of technical secondary alkanesulfonates determined by pyrolysis gas chromatography and mass spectrometry (GC-MS) is shown in Fig. 13 together with the corresponding carbon number pattern of the raw material paraffins obtained by GC [16]. Pyrolysis was performed in a crucible-modified SGE pyrojector after covering the mixture with quartz wool. The presence of up to 10 wt % of disulfonates in technical alkanesulfonates is demonstrated by fast atom bombardment and mass spectrometry (FAB-MS) (Fig. 14) [24],... 

The reactor is an 8-mm i.d. quartz tube located in a tube furnace. The quartz tube is packed with 20 by 30 mesh catalyst particles. The catalyst bed is positioned in the tube using quartz wool above and below the bed, with quartz chips filling the remainder of the reactor. The furnace temperature is controlled by a thermocouple inserted into the reactor tube and positioned about 3 mm above the catalyst bed. This allows operation at constant feed temperature into the reactor. 

Carburization was carried out in a fixed-b i stainlras strel reactor (ID = 6 mm). Typically about 0.5 g of metal sulphide was sandwiched between 2 layers of quartz wool placed centrally in a temperature-programmed furnace. iTie sample was heated at 10 Kmin" to the... 

Preparation of column. Pack the chromatographic tube in the following order a quartz-wool plug, 1.0 g of silica gel (deactivated with 1.5% water), then a 5-10-mm layer of sodium sulfate. Finally, insert a small amount of quartz-wool on top of the column packing. Before use, rinse the column with 5 mL of n-hexane and discard the eluate. 

Quartz wool, extracted exhaustively with acetone... 

Experiments were carried out in a U-type quartz reactor. The sample (0.025-0.2 g) was held between plugs of quartz wool and the temperature was monitored through a WET 4000 or Eurotherm 2408 temperature controllers. Reactant gases were fed from mass flow controllers (Brooks 5850TR). 

Temperature programmed reduction (TPR) experiments. TPRs were performed for each material using a quartz reactor tube (4 mm i d ), in which a 100 mg sample was mounted on loosely packed quartz wool. Samples were predried overnight at 120 °C. The sample was heated at 5 °C /min up to 700 °C under 20 mL/min flow of a 2 1 mixture of H2 Ar. 

Figure 3.38 — Integrated flow-through sensors. (A) With electrochemical generation of the luminescent reagent. The flow stream path follows the line between the analyte inlet and the outlet to waste. (B) With immobilization of a phosphor (length, 3 cm internal diameter, 2 mm) 1 immobilized phosphor 2 CFG 3 quartz wool plug 4 KEL-F caps 5 hand-tightened screw 6 stainless steel capillaries. (C) Sensor based on reflectance measurements. The sensor membrane is fixed on a Plexiglas disc. Reflectance spectra are measured from the rear side. (Reproduced from [267] and [269] with permission of the American Chemical Society and Elsevier Science Publishers, respectively).

Sulphur dioxide can be removed at 450° using silver wool combined with a plug of platinized quartz wool. Halogens are removed by using Mg, Zn or Cu, heated to 450°. 

The catalyst was placed in the reactor and held by two small plugs of quartz wool. Prior to the reactions, the catalysts were heated in a helium stream (60 ml/min) at 450°C for 30 min and then heated in an ammonia stream at the reaction temperature for 30 min. The reaction temperature was measured by a chromel-alumel thermocouple placed adjacent to the catalytic zone of the reactor. For each pulse, 5 p of the reactant (chlorobenzene or benzaldehyde) were injected by a microsyringe. 

Deactivated catalysts (5.4-5.5 mg) were loaded at ambient conditions into a 0.1 cm id X 2.0 cm quartz tube having one sealed end. Catalyst was held in place with a plug of Amersil quartz wool. Both quartz wool and tubes were baked out at 500°C for one hour prior to use. The loaded tube was placed into the electrically heated tip of the solids probe of a DuPont model 21-491 mass spectrometer operated at 1 X 10 7 torr. The solids probe was located in the mass spectrometer so that its tip, through which desorbing hydrocarbon molecules passed, was immediately adjacent to the ion source. The probe temperature was raised from 38° to 385°C in 22 minutes. Spectral scanning was conducted automatically every 30 seconds from approximately mje 16 to ra/e 650 at 10 sec/decade. 

The catalyst pretreatment process for both the clay-supported and the reference catalysts consists of loading into the HDS reactor under N2, purging in N2 at 20°C for 30 min at 1000 cmVmin., drying in N2 at 150°C for 60 min and at 400°C for 60 min, and finally sulfiding in a 5% H2S/H2 mixture at 400°C for two hr prior to use as catalysts. The laboratory scale liquid-phase continuous-flow HDS reactor consists of a thick-walled 0.375" ID 316 SS tube, with 1 g catalyst diluted with 5 g tabular alumina (LaRoche T-1061, 10 m2/g) sitting between plugs of quartz wool. Beneath the lower plug is a 0.125" ID, 0.375" OD deadman used to minimize volume between the reactor and the liquid receiver. The liquid test feed consisted of 0.75 wt % sulfur as dibenzothiophene (DBT), dissolved in hexadecane and is representative of a middle distillate oil. All liquid-filled lines were heated to 50°C. The reaction was carried out at 400°C LHSV = 10-40/hr. 

The isomerization reactions of pentafluorophcnyl and heptafluoro-2-naphthyl propargyl sulfides have been studied under a variety of conditions.38 For example, the naphthyl sulfide rearranges to the fluoromethyl derivative 46 in 81 % yield when distilled at 360 C in vacuo through a glass tube packed with quartz wool. 

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