N2 Purge

Methods presented below can be used individually or in combination. 2.12.2.1 N2 Purge 

---

A typical arrangement for a voltammetric electrochemical cell is shown in Figure 11.28. Besides the working, reference, and auxiliary electrodes, the cell also includes a N2 purge line for removing dissolved O2 and an optional stir bar. Electrochemical cells are available in a variety of sizes, allowing for the analysis of solution volumes ranging from more than 100 mL to as small as 50 )+L. 

Fig. 4. Equipment flow sheet of elemental fluorine production and liquefaction plant, 9 t/d capacity. Step 1 purging residual F2 at rates indicated all but a trace of residual F2 is removed in 15min N2 purge is maintained for 1 h to remove last traces. Step 2 HF removal at rates indicated all but a trace of HF is...

The majority of detectors, which are employed for the measurement of absorption, employ UV glass (e.g. Suprasil). AU type S-5 photomultiphers possess sheaths of this material, so that they ought to be usable in the far UV region if N2 purging IS employed (to remove O2) (Tab. 4). 

Before the measurement of HOR activity, a pretreatment of the alloy electrode was carried out by potential sweeps (10 V s ) of 10 cycles between 0.05 and 1.20 V in N2-purged 0.1 M HCIO4. The cyclic voltammograms (CVs) at all the alloys resembled that of pure Pt. As described below, these alloy electrodes were electrochemically stabilized by the pretreatment. Hydrodynamic voltammograms for the HOR were then recorded in the potential range from 0 to 0.20 V with a sweep rate of 10 mV s in 0.1 M HCIO4 saturated with pure H2 or 100 ppm CO/H2 at room temperature. The kinetically controlled current 4 for the HOR at 0.02 V was determined from Levich-Koutecky plots [Bard and Faulkner, 1994]. 

Measure a 1000 mL aliquot of sample solution and transfer to the top of the Cig SPE cartridge column which was conditioned with 5 mL of ethyl acetate, 5 mL of methanol and 10 mL of distilled water in advance at an elution rate of 10 mL min . After washing the column with 10 mL of distilled water, dry the column with suction for 30 min, then elute with 0.5 mL of acetone and then 5 mL of ethyl acetate. Dry the eluates using a rotary evaporator at 35 °C and by N2 purging. 

FIGURE 1.4 Absorption spectrum of 125 obtained by LFP of 124 in N2 purged aqueous acetonitrile. Source Data taken with permission from Ref. [40]. 

Photochemistry of Model Compounds. Preliminary photochemical studies have been carried out on l,3-diphenoxy-2-propanol (3)8 as a model compound for bisphenol A-epichloro-hydrin condensates 1. The utilization of 3 as a model compound for thermal degradation of 1 has been reported. Irradiation (254 nm) of 3 in acetonitrile (N2 purge) provides two major volatile products, which have been identified as phenol and phenoxyacetone (4), by comparison of retention times (gas chromatography) with known samples. A possible mechanism for... 

All solvent-containing process vessels are N2 purged and maintained under N2 pad or blanket. 

FIGURE 14.5. FTIR spectra for CO adsorption on Au72Pt28/Si02 catalyst calcined at 400°C under two different sample preparation conditions (A and B). N2-purging times 0 min (the spectrum was corrected by subtracting the gas-phase CO spectrum) (A), and 1 min (top) and 52 min (bottom (the gas-phase CO is absent)) (B). 

Trimethylamine alane has been used for A1 deposition on various SAMs functionalized with —COOH, -OH, and -CH3 terminal groups. No reaction was observed with -CH3 but reactions were observed with -OH and -COOH. In the latter cases room temperature deposition created A1 oxide and A1 layers under conditions of N2 purging and UHV, respectively [79, 88, 89]. 

After the solvent is added, the septum is replaced with a reflux condenser, topped with an N2-CO gas outlet, which is connected to a mineral oil bubbler. The reaction mixture is stirred at reflux for 12 h, and a slow N2 purge is maintained throughout this period. After cooling to room temperature, the gray-green powder is isolated by filtration, washed with 2 x 50 mL of fresh chlorobenzene, followed by 4 x 50 mL of hexane, and dried in vacuo (10 storr, 25 °C, 8h). It is important to free the product of all traces of chlorobenzene in order to obtain clean reductions in the following syntheses. Yield 47 g (or 96% based on WC16). 

Preparation of [Mo(N2)2(dppe)2]. A solution of 225 mg of [MoH dppe ] dissolved in 100 mL of benzene was irradiated with 366 nm for 12 hr under a continuous N2 purge. The solution changed from yellow to orange, and with a decrease in concentration to 10 mL followed by the addition of 75 mL of dried, degassed MeOH, the solution gave a 220 mg precipitate of [Mo(N2)2(dppe)2], a yield of 93%. 

N2-purged solutions of 5x1 O 4 mol dm"3 of the sterically hindered phenols in acetonitrile were photolyzed with fs-pulses. After tens of picoseconds a band between 400 and 450 nm... 

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. 

---