Oxidation products stainless steel reactor

For the production of tartar emetic (antimony potassium tartrate [28300-74-5]), potassium bitartrate [868-14 ] and antimony oxide, Sb202, are added simultaneously to water in a stainless-steel reactor. The reaction mixture is diluted, filtered, and collected in jacketed granulators where crystallization takes place after cooling. Centrihiging, washing, and drying complete the process. 

Product C also contained iron and chromium suggesting the use of a stainless-steel reactor for processing. Even these small levels of metals may contribute to rapid oxidation of product C, and it probably has a shortened shelf-life when compared with the other products. 

A tubular stainless steel reactor (I.D. 104 mm) heated by an electrical oven at atmospheric pressure is used for the oxidation of toluene [Fig. 1]. The toluene is dosed with an HPLC pump (LKB2150) to an evaporator at 320 °C and then mixed to the O2 and N2 flows which are controlled with mass flow controllers (Bronkhorst High-Tech B. V ). Nitrogen is used as diluent. The catalyst fixed-bed preceded by quartz beads is maintained between quartz wool. The temperature of the fixed-bed is measured with a K-type thermocouple (Philips AG). The outlet gases are cooled in three consecutive condensers. The liquid products are collected and analysed by gas chromatography with a flame ionisation detector for quantification (Perkin-Elmer Autosystem gas chromatograph, capillary column Supelco SPB-1, 30 m x 0.53 mm I.D. X 0.50 jum film thickness) and with an electron ionisation detector for identification (Hewlett-Packard, G1800A, GCD System, capillary column HP-5, 30 m x 0.25 mm I.D. x 0.25 fm film thickness). The experiments are carried out at a conversion less than 5 per cent. 

The pretreatment of the metal reactors effected the product composition. For example, as shown in Figure 1, one of the runs in the Incoloy reactor having a reduced inner surface had at a given ethane conversion a product composition similar to that for the Vycor reactor. Yet a second run in which the Incoloy reactor had a more oxidized surface resulted in a product containing less ethylene and more hydrogen the product for the second run was relatively similar to that for the stainless steel reactor. 

At pyrolysis conditions, steam and oxygen react with Iron, nickel, and chromium to form oxides of these metals (1,2). Crynes and Albright (3), In their 304 stainless steel reactor, found that metal oxides were formed on the Inner wall of the reactor used for propane pyrolysis. These metal oxides apparently often promote secondary and undesired reactions that reduced the yield of products. More recently, Dunkleman, Brown, and Albr1ght(4,5) have reported more evidence confirming the undesirability of these metal oxides. 

Production and Destructiy of Metal Sulfides. Hydrogen sulfide was passed on two different occasions through a preoxidized stainless steel reactor (i.e. one that had considerable metal oxides on the surface). On both occasions, both water and sulfur dioxide were produced in significant amounts especially during the initial stages of the run. At least part of the hydrogen sulfide decomposed, perhaps in the gas phase, as follows ... 

Then at 550-575°C in the Incoloy reactor and at 575-600°C in the 304 stainless steel reactor, significant reactions were noted. Products were obtained of what was apparently both gas-phase free-radical reactions and surface deconposition reactions coke and carbon oxides were both formed in significant amounts. The production of carbon oxides indicated that the propylene was reacting with surface oxides on the reactor surface. The level and the types of surface oxides were changing (e.g. Fe O was probably converted to Fe,0, or FeO), hence changing the sorface activ-... 

Carbon steel, monel-400, zircalloy-2 and stainless steel form the major materials of construction in the PHWRs. Out of the total surface area of these construction materials exposed to the PHT system about 94% can be attributed to carbon steel, monel-400 and zircalloy-2, and only about 6% to stainless steel. The major chemical constituents of the oxide film are magnetite and nickel ferrite. Activated corrosion products Co-60, Mn-54, etc., and fission products Cs-137, Ce-144, Ru-103, Ru-106 are the contaminants in the oxide film. Stainless steel is the chief construction material for Boiling Water Reactor systm and the major contaminant film consists of chromium rich ferrites. 

In experiments on a pilot plant with a flow stainless steel reactor at a gas flow rate of 1000 m /h [78], among the oxidation byproducts, normal C2—C4 alcohols and acetone were identified, the yield of which relative to the methanol yield ranged from 2% for ethanol to less than 0.2% for butanol. The formation of C2—C4 products in this work is most likely associated with the use of natural gas, although its composition was not specified. 

A strong influence of the reactor surface material on a slow (fr 50—100 s) DMTM process was demonstrated in [41,86]. The authors used a stainless steel reactor with an inner quartz insert firmly planted on O-rings, which eliminated the contact of the heated reactants and products to the metal surface. The products were quickly carried away from the hot zone to stop the radical reactions and prevent further oxidation. The data show that, in this case, the selectivity of methanol formation at P = 50 atm, T = 450 °C, and a mixture composition of [CH4] [02] [N2] = 100 10 10 reached a very high value, 62.3%, with an yield of 8.2%. When the O-rings were removed, a modification that presumably allowed the reagents to penetrate into the gap between the quartz insert and the stainless steel surface, the selectivity and yield dropped to values typical of these conditions, 31.6 and 2.9%, respectively. 

A well-pronounced dependence of the yield of DMTM products on the reactor surface material (quartz vs. stainless steel) at a short residence time ( 2s), especially strong at lower pressures, was observed in [91] (Fig. 3.14). Only at high pressures, close to 80 atm, the difference becomes insignificant. At this pressure, both materials provided nearly the same maximum yield of methanol, which was achieved, however, at different oxygen concentrations 3.5% O2 for the stainless steel reactor and 6—8% O2 for the quartz reactor (Fig. 3. 40). Such a sharp distinction can be explained not only by different rates of the heterogeneous activation of methane and decomposition of the products on these surfaces, but also by different rates of the heterogeneous oxidation of methane to deep-oxidation products, CO2 and H2O. 

Two types of continuous flow solid oxide cell reactors are typically used in electrochemical promotion experiments. The single chamber reactor depicted in Fig. B.l is made of a quartz tube closed at one end. The open end of the tube is mounted on a stainless steel cap, which has provisions for the introduction of reactants and removal of products as well as for the insertion of a thermocouple and connecting wires to the electrodes of the cell. A solid electrolyte disk, with three porous electrodes deposited on it, is appropriately clamped inside the reactor. Au wires are normally used to connect the catalyst-working electrode as well as the two Au auxiliary electrodes with the external circuit. These wires are mechanically pressed onto the corresponding electrodes, using an appropriate ceramic holder. A thermocouple, inserted in a closed-end quartz tube is used to measure the temperature of the solid electrolyte pellet. 

A microchannel reactor for CO preferential oxidation was developed. The reactor was consisted of microchannel patterned stainless steel plates which were coated by R11/AI2O3 catalyst. The reactor completely removed 1% CO contained in the Ha-rich reformed gas and controlled CO outlet concentration less than Ippm at 130 200°C and 50,000h. However, CH4 was produced from 180"C and CO selectivity was about 50%. For high performance of present PrOx reactor, reaction temperature should be carefully and uniformly controlled to reach high CO conversion and selectivity, and low CH4 production. It seems that the present microchaimel reactor is promising as a CO removal reactor for PEMFC systems. 

The oxygen and radiolysis products attack the outer layers of the stainless steel or nickel-based alloys used in the reactor structure, forming a thin oxide layer on these components. Corrosion products are released from this thin oxide layer by... 

The benefits of the use of micromembranes for the selective removal of one or more products during reaction have been demonstrated for equdibrium-limited reactions [289]. For example, the performance of hydrophilic ZSM-5 and NaA membranes over multichannel microreactors prepared from electro-discharge micromachining of commercial porous stainless steel plates was studied by Yeung et al. in the Knoevenagel condensation [290,291] and andine oxidation to azoxybenzene [292]. For such kind of reactions, the zeolite micromembrane role consists of the selective removal of water, which indeed yields higher conversions, better product purity, and a reduction in catalyst deactivation in comparison to the traditional packed bed reactor. 

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