Hydrothermal testing

Investigations performed by Dupont on the chemical stability of Teflon reveal that Teflon immersed in a 20% HC1 solution at 200°C for extended periods will not absorb any chlorine within detectability limits. In addition, Teflon does not absorb any detectable sulfur from sulfuric acid or sulfur vapor. Therefore, a Teflon H, membrane may prove to be superior to a platinum-group metal membrane for use in sulfur- or chlorinebearing systems. Investigations are currently being performed to determine the feasibility of employing a Teflon membrane as an H2 monitor/controller in hydrothermal test apparatus. 

Figure 54. Test cell used for studying the general corrosion of Type 304 SS in HCl + NaCl solutions at temperatures ranging from 150"C to 400°C. (a) ENA sensor and data aequisition system, (b) Schematic of hydrothermal test cell. Reprinted from Ref. 140, Copyright (2009) with permission from Elsevier.

Under heated or hydrothermal conditions, the possible degradation mechanism for AEMs has been discussed in the literatures. Hydrolytic stability of the AEMs is performed by treating the membrane in hot water for a specific period. Only a few reports are concerned with the hydrolytic stability so far. For Watanabe research gronps, they performed the hydrolytic stability test in hot water at 80 C for 500 h the chemical structures before and after the hydrothermal test were analyzed by the use of H NMR spectra. A long-term hydrothermal test was also performed for 5000 h, and the ionic conductivity was used to assess the stability. According to their results, the major degradation mode of the AEM (based on quaternary PES) under the hydrothermal condition is most likely to be the elimination of a tertiary amine to form benzyl alcohol and its further decomposition via dehydration. ... 

Richter S, Goldberg SA, Mason PB, Traina AJ, Schwieters JB (2001) Linearity tests for secondary electron multipliers used in isotope ratio mass spectrometry. Inti J Mass Spectrom 206 105-127 Rihs S, Condomines M, Sigmarsson O (2000) U, Ra, and Ba incorporation dining precipitation of hydrothermal carbonates imphcations for Ra-Ba dating of impure travertines. Geochim Cosmochim Acta 64 661-671... 

Hydrothermal stability (HTS). The stability of the chlorinated resins was determined by a test procedure described in the experimental. The resin according to the standard test is treated with water in a sealed flask at 200 °C for 24 hours to determine the loss in acid functionality and additionally, the level of chlorine released into the aqueous phase. 

Mobile, on-line XRF methods have been tested in the Au exploration targets. Analysis of continuous till and weathered bedrock samples shows clear variation of the contents of pathfinder elements of hydrothermal alteration. Particularly, in the weathered bedrock, the presence of narrow mineralized veins is seen (Fig. 5). One interesting feature is that the indication of the weathered bedrock sources can be traced 2 to 5 m down-ice in the till. These results suggest very short glacial transport of mineralized debris from the bedrock sources. Information on... 

Recently, mesoporous aluminosilicates with strong acidity and high hydrothermal stability have been synthesized via self-assembly of aluminosilicate nanoclusters with templating micelles. The materials were found to contain both micro- and mesopores, and the pore walls consist of primary and secondary building units, which might be responsible for the acidity and stability (181). These materials were tested in isobutane/n-butene alkylation at 298 K, showing a similar time-on-stream behavior to that of zeolite BEA. No details of the product distribution were given. 

These ideas are readily testable and therefore can constitute a research enterprise. For example, the hydrolysis of polyphosphates to monomeric phosphate is relatively fast in weak aqueous acid and warm temperatures. [129, 205] Curiously, however, the same acidity would promote thermal polyphosphate synthesis under the dehydrating conditions of the heated subterranean mineral pores within a hydrothermal system. Measurement of the stability of polyphosphates in microscopic environments where the activity of water might be low would test the phosphate-polyphosphate conjecture made above. If polyphosphates are not stabilized relative to bulk water solutions, as dissolved within micron-sized mineral pores or within vesicles, perhaps in the presence of dissolved organics, then this hypothesis is in danger. Additionally, the proposed production and delivery of polyphosphates by hydrothermal systems can be tested in an appropriate laboratory setting. 

Cao et al. produced HTC/Sn nanocomposites by hydrothermal treatment of sucrose and SnCl4 solution [37]. After the carbon was removed, the electrochemical properties of the hollow Sn02 materials were tested. This material has a high initial dis-... 

Geological and geochemical applications of PXRF generally require multi-element analysis however, the more elements that are included within an analytical test, the greater the likelihood of problems such as peak overlaps or interferences, and manufacturers typically will provide machine calibrations for 20-30 elements in a particular analytical mode (see below). Our instruments have been calibrated for a range of elements for characterization of lithological units, different mineralization types and associated hydrothermal alteration, and other geochemical exploration vectors. 

It could be expected, that combustion reactions and possibly flames can be produced in such dense supercritical mixtures. Technical aspects of hydrothermal oxydation at moderate pressures have already been tested and discussed [7,8]. The study of combustion and flames in supercritical phases offers several possibilities 1. The variation of pressure over wide ranges should influence reaction mechanisms and flame characteristics because the density can be changed from low, gas-like, to high, liquid-like, values. 2. The variable temperature of the dense, fluid environment can have an influence on reactions and flames. 3. The chemical and physical character of this environment can be varied considerably, for example by using supercritical water as the major component, as in the present experiments. Certainly, the knowledge of transport coefficients of gases involved is desirable. For water the viscosity has been determined to... 

Analysis of two nickel-containing DFCC revealed that neither heating in air or in steam induced intraparticle transfer of nickel at the thermal and hydrothermal conditions used to age the fresh catalysts (11) prior to microactivity testing. 

CATALYST PREPARATION AND TESTING. The Y-containing catalysts examined in this study were prepared either by 1) a microunit accelerated metals laydown technique or 2) by a simulated deactivation procedure involving hydrothermal treatment of Y-doped catalysts. 

Catalyst hydrothermal deactivation was carried out in two different equipments a lOOg capacity fixed bed steamer was used for the advanced cracking evaluation (ACE) unit tests and a 5 kg capacity fluidized bed steamer was used for the other testing protocols. Steaming conditions in the two cases were the same 788°C for 5 hours under 100% steam flow. Although conditions were similar, higher pressure buildup in the fixed bed steamer led to lower surface area retentions. 

The catalyst used in this study corresponds to a fresh commercial catalyst used in one FCC unit of ECOPETROL S.A. This solid is hydrothermal deactivated at the laboratory in cycles of oxidation-reduction (air-mixture N2/Propylene) at different temperatures, different times of deactivation, with and without metals (V and Ni), and different steam partial pressures. Spent catalysts (with coke) are obtained by using microactivity test unit (MAT) with different feedstocks, which are described in Table 10.1. 

The catalysts with metals are previously impregnated with solutions of vanadyl and nickel naphtenates based on the Mitchell method [4], Before hydrothermal deactivation the samples were calcined in air at 600°C. The activity was performed in the conventional MAT test using 5 grams of catalyst, ratio cat/oil 5, stripping time 35 seconds, and reaction temperature 515°C. Elemental analyses to determine the total amount of carbon in the spent catalysts were done by the combustion method using a LECO analyzer. 

This type of coke depends exclnsively on the FCC cracking activity. In order to have samples with different activity and little inflnence of contaminant coke, the fresh catalyst was deactivated hydrothermally at different severity conditions withont metals. MAT test for these deactivated samples was performed with VGO as a feedstock to diminish coke yields. 

Figure 3. (A) XRD patterns and (B) N2 adsorption/desorption isotherms of the calcined mesoporous silica ropes obtained from the C,6TMAB-HNO3-TEOS-(PEO-6000)-H2O system before and after the post-synthesis ammonia treatment at 100 °C and a further hydrothermal stability test in water at 100 °C.

The synthesis of MCM-41 was carried out according to the following molar compositions of Si02 NaOH CTMABr Acid H20= 1 x y z 100, where Acid stands for HF or HC1, and molar ratios x, y, and z can be changed accordingly. A detailed synthesis procedure has been reported elsewhere [12]. For the hydrothermal stability studies, 0.5 g of the solid calcined at 550 °C for 10 h in air was tested in 60 g of boiling water in a plastic bottle for several days. 

Hydrothermal Stability Test. Hydrothermal stability of the synthesized samples was investigated by mixing about 0.2 g of the calcined sample with 20 g deionised water and heating in a closed bottle at 100°C under static condition for different time periods. After hydrothermal treatment the solid was filtered, washed with deionised water and dried at 70°C for overnight. Hydrothermal stability was followed by measuring the XRD peak intensities. 

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