Vapor-phase oxidation inhibitors

The per pass ethylene conversion in the primary reactors is maintained at 20—30% in order to ensure catalyst selectivities of 70—80%. Vapor-phase oxidation inhibitors such as ethylene dichloride or vinyl chloride or other halogenated compounds are added to the inlet of the reactors in ppm concentrations to retard carbon dioxide formation (107,120,121). The process stream exiting the reactor may contain 1—3 mol % ethylene oxide. This hot effluent gas is then cooled ia a shell-and-tube heat exchanger to around 35—40°C by usiag the cold recycle reactor feed stream gas from the primary absorber. The cooled cmde product gas is then compressed ia a centrifugal blower before entering the primary absorber. 

Phosphine Oxides. Development of cyanoethylphosphine oxide flame retardants has been discontinued. Triphenylphosphine oxide [791 -28-6] C gH OP, is disclosed in many patents as a flame retardant, and may find some limited usage as such, in the role of a vapor-phase flame inhibitor. 

In that same pnblication, Chnrch and Pryor (746) stated that the vapor phase of cigarette smoke contains small oxygen-and carbon-centered radicals that are mnch more reactive than the particnlate-phase radicals. Althongh no vapor-phase radicals were specifically identihed, they stated that the vapor-phase radicals do not arise from the initial combustion of the tobacco, bnt are rather prodnced in a steady state by the oxidation of NO to NO2, which then reacts with reactive species already present in smoke, snch as isoprene. They suggested that these reactive vapor-phase free radicals and the metastable prodncts derived from the radical reactions may be responsible for the inactivation of al-proteinase inhibitor by fresh smoke. 

Ammonium dimolybdate corrosion inhibitor, vapor-phase Dicyclohexylamine nitrite 2-Dimethylamino-2-methyl-1-propanol corrosion inhibitor, waterfloods Cocodiamine acetate Etidronic acid corrosion inhibitor, water systems Acrylic resin Hydrazine corrosion inhibitor, water treatment Ammonium dimolybdate Calcium oxide Etidronic acid Lauramine 2-Mercaptobenzothiazole Myristamine Myristamine acetate PEG-8 dioleate PEG-3 tallow aminopropylamine PEG-8 tallow aminopropylamine Potassium phosphate Potassium thiocyanate Potassium tripolyphosphate Sodium chromate Sodium molybdate dihydrate... 

Phosphorus could act as char promoter, but also in the vapor phase. The partition of phosphorus between condensed and vapor phases and its modes-of-action (as char promoter, flame inhibitor, etc.) depend strongly on various parameters. Phosphine oxide seems to be a relatively poor char promoter. Generally, a high oxidation state should allow more efficient... 

Oxygen and liquid CTFE react and form peroxides at fairly low temperatures. A number of oxygenated products are produced as a result of oxidation of chlorotrifluoroethylene, such as chlorodifluoro-acetylfluoride.f l The same reaction can occur photo-chemically in the vapor phase. Chlorotrifluoroethylene oxide is a by-product of this reaction. The peroxides act as initiators for the polymerization of CTFE, which can occur violently. This is the reason that all traces of oxygen must be removed for safe storage and shipping without the addition of inhibitors. 

Minor uses of vanadium chemicals are preparation of vanadium metal from refined pentoxide or vanadium tetrachloride Hquid-phase organic oxidation reactions, eg, production of aniline black dyes for textile use and printing inks color modifiers in mercury-vapor lamps vanadyl fatty acids as driers in paints and varnish and ammonium or sodium vanadates as corrosion inhibitors in flue-gas scmbbers. 

Retardation and Inhibition. In order to obtain additional information on the polymerization process, various potential inhibitors or retarding agents were added to carbon suboxide, and the rate of polymer deposition from the gas phase was quantitatively studied at 100°C. To the monomer at a pressure of 330 mm Hg was added either an equimolar quantity of inhibitor based on pressure measurements, or room temperature vapor pressure of additive if less than 330 mm Hg. The additives used were oxygen, nitric oxide, 3-methyl-1-butene, 1,3-butadiene, acetone and acetaldehyde. Polymerization rates were followed by ESR measurements. 

There is a very wide range of inhibitors available to stabilize MDC, but it is best to avoid aluminium as a material of construction when MDC may be processed or stored. Because of MDC s volatility there is always a danger that it will distil away from a less volatile inhibitor and lose its protection. Low-boihng inhibitors such as te/t-butylamine, propylene oxide and amylene (2-methylbut-2-ene) tend to stay with MDC when it is vaporized whereas dioxane, ethanol, THF, N-methyhnorpholine and cyclohexane tend to remain in the liquid phase. The concentrations required for effective inhibition are low (50 ppm to 0.2%) and, if MDC is used as a reaction medium, it is almost always possible to find one that does not become involved in the reaction itself. 

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