Carbon monoxide/ethylene decomposition

It seems to be well-established that methane and ketene are formed in the main reaction, while carbon monoxide, ethylene and other products, produced in trace amounts, are probably the result of the ketene decomposition. Ethane and acetonyl acetone are chain termination products (see later), while the precursor of acetyl acetone is probably the radical formed in the reaction of the acetonyl radical and the ketene. 

With the exception of formic acid, the lower fatty acids are quite stable np to relatively high temperatures. Cahours and Berthelot early notedos the thermal stability of these acids, and the latter reported that acetic acid did not decompose until above a dull red heat. More recently Senderens showed that acetic, propionic, /i-butyric, isobutyric, and isovaleric acids were perfectly stable at temperatures as high as 460° C.os At higher temperatures these acids undergo pyrogenic decomposition to yield simple and stable substances. In the case of acetic acid, Nef 01 reported the presence of methane, carbon dioxide, carbon monoxide, ethylene, hydrogen, and acetone in the products from decomposition. 

Of particular interest in this chapter are the specific hazards associated with the combustion of methane, hydrogen, ethylene, and carbon monoxide, the decomposition of ethylene and of ozone, and the reaction of a variety of combustibles in air, oxygen, and fluorine. 

The surface reactivity of TMCs has attracted considerable attention because of their use as catalytic materials for the hydrogenation of benzene, ethylene, and carbon monoxide the decomposition of methanol etc. (1). Studies of gas adsorption on well-defined surfaces of TMCs have been performed for some systems, and it has been found that the surface reactivity of TMCs shows considerable face dependence the surface reactivity toward gas adsorption of (111) is much higher than that of (100). For example, oxygen adsorption studies of TiC(lOO) and (111) surfaces have shown that the sticking probability of oxygen on (111) is two orders of magnitude... 

Oxychlorination of Ethylene or Dichloroethane. Ethylene or dichloroethane can be chlorinated to a mixture of tetrachoroethylene and trichloroethylene in the presence of oxygen and catalysts. The reaction is carried out in a fluidized-bed reactor at 425°C and 138—207 kPa (20—30 psi). The most common catalysts ate mixtures of potassium and cupric chlorides. Conversion to chlotocatbons ranges from 85—90%, with 10—15% lost as carbon monoxide and carbon dioxide (24). Temperature control is critical. Below 425°C, tetrachloroethane becomes the dominant product, 57.3 wt % of cmde product at 330°C (30). Above 480°C, excessive burning and decomposition reactions occur. Product ratios can be controlled but less readily than in the chlorination process. Reaction vessels must be constmcted of corrosion-resistant alloys. 

Thermal Decomposition. The therm decompn was studied betw 380 and 430° and found to be homogeneous and apparently 1st order. The products were complex and included nitric oxide, methane, carbon monoxide, and w plus small amts of ethane, ethylene, and nitrous oxide (Ref 23)... 

During the vacuum fractional distillation of bulked residues (7.2 t containing 30-40% of the bis(hydroxyethyl) derivative, and up to 900 ppm of iron) at 210-225°C/445-55 mbar in a mild steel still, a runaway decomposition set in and accelerated to explosion. Laboratory work on the material charged showed that exothermic decomposition on the large scale would be expected to set in around 210-230°C, and that the induction time at 215°C of 12-19 h fell to 6-9 h in presence of mild steel. Quantitative work in sealed tubes showed a maximum rate of pressure rise of 45 bar/s, to a maximum developed pressure of 200 bar. The thermally induced decomposition produced primary amine, hydrogen chloride, ethylene, methane, carbon monoxide and carbon dioxide. 

Diazomethane when heated with copper powder gives nitrogen and an insoluble polymethylene, indicating that one of its reactions is the decomposition into methylene radicals. The methylene radical can also be formed in the gas phase and detected by a mirror experiment.81 The pyrolysis of ketene in the gas phase gives carbon monoxide and methylene radical. The methylene radical both reacts with itself to give ethylene and removes tellurium mirrors, forming tellurform-aldehyde.82 Thus the methylene diradical(P) behaves as expected. 

The tabulated data have been obtained for the vapor phase decomposition of ethylene oxide (A) into methane and carbon monoxide at 414.5°C (Heppert Mack, JACS 5J 2706, 1929). Show that the rate equation is first order, nt = 2na0-na... 

According to H. Rose,47 dry powdered ammonium chloride at 0° absorbs the vapour of sulphur trioxide without decomposition, forming a hard mass which, when heated, first develops hydrogen chloride, and forms ammonium sulphate— it has been suggested that the product may be ammonium chloropyro-sulphate, NH4.0.S205C1. With carbon monoxide at a red heat, C. Stammer observed no changes, but with calcium carbide, R. Salvadori obtained calcium chloride, nitrogen, ammonia, carbon, and a series of hydrocarbons—methane, ethylene, and acetylene. 

With respect to the untreated Reactor I, the hydrogen peroxide yield was very small, and that of methane, ethylene, carbon monoxide, and acetaldehyde was large. The small ratio of hydrogen peroxide to propylene is possibly caused by the successive decomposition of hydrogen peroxide once formed. With aged Reactor II, the yield of hydrogen peroxide and methanol increased, while that of methane, ethylene, and carbon monoxide decreased significantly. 

When ethylene-vinyl acetate copolymers are manufactured, the decomposition products also contain carbon monoxide and carbon dioxide. When decomposition takes place in a tubular reactor or in a multi-chamber or cascade of autoclaves, up to 50% of the decomposition gases can consist of undecomposed ethylene. 

Acrylic acid [79-10-7] - [AIR POLLUTION] (Vol 1) - [ALDEHYDES] (Vol 1) - [ALLYL ALCOHOL AND MONOALLYL DERIVATIVES] (Vol 2) - [MALEIC ANHYDRIDE, MALEIC ACID AND FUMARIC ACID] (Vol 15) - [POLYESTERS, UNSATURATED] (Vol 19) - [FLOCCULATING AGENTS] (Vol 11) - [CARBOXYLICACIDS - SURVEY] (Vol 5) -from acetylene [ACETYLENE-DERIVED CHEMICALS] (Vol 1) -from acrolein [ACROLEIN AND DERIVATIVES] (Vol 1) -acrylic esters from [ACRYLIC ESTER P OLYMERS - SURVEY] (Vol 1) -from carbon monoxide [CARBON MONOXIDE] (Vol 5) -C-21 dicarboxylic acids from piCARBOXYLIC ACIDS] (Vol 8) -decomposition product [MAT. ETC ANHYDRIDE, MALEIC ACID AND FUMARIC ACID] (Vol 15) -economic data [CARBOXYLIC ACIDS - ECONOMIC ASPECTS] (Vol 5) -ethylene copolymers [IONOMERS] (Vol 14) -in floor polishes [POLISHES] (Vol 19) -in manufacture of ion-exchange resins [ION EXCHANGE] (V ol 14) -in methacrylate copolymers [METHACRYLIC POLYMERS] (Vol 16) -in papermaking [PAPERMAKING ADDITIVES] (Vol 18)... 

CARBENE. The name quite generally used for the methylene radical, CH,. It is formed during a number of reactions. Thus the flash photochemical decomposition of ketene (CH2=C=0) has been shown to proceed in two stages. The first yields carbon monoxide and CHj. the latter then reacting with more ketene to form ethylene and carbon monoxide. Carbcne reacts by insertion into a C- H bond to form a C-CH, bond. Thus carbene generated from ketene reacts with propane to form, i-butane and isobutane. Carbene generated by pyrolysis uf diazomethane reacts with diethyl ether to form ethylpropyl ether and ethylisopropyl ether. 

The thermal decomposition of ketene into carbon monoxide and ethylene is prevented, as far as possible, by the rapid removal of ketene from the hot tube, which is accomplished by the undccomposed acetone vapor. About half the acetone originally used should be collected unchanged as distillate by the vertical condenser. The yield of ketene will fall considerably if less distillate is formed. 

Experiments on the decomposition of the ketone in the presence of oxygen (Table I) strongly indicate that the formation of ethylene, cyclobutane (and, by inference, carbon monoxide), and pentenal is not affected by even 35.5 mm. of oxygen. This may be compared with the... 

Photolysis of cyclobutanone leads to the formation of ethylene, ketene, carbon monoxide, propylene (3), and cyclopropane (5). The formation of an isomeric product, presumed to be 3-butenal, in small yield has been reported (31). The yields of ethylene and ketene have been found to be approximately equivalent (6). The yield of carbon monoxide is in excess of the yield of hydrocarbons (5,6). The discrepancy has been attributed to the formation of a polymer (5) although no direct evidence to substantiate this explanation has been obtained. The stoichiometry of the decomposition may be represented by the following equations ... 

Compound 1 exhibits significantly different reactivity than the acyclic analogue. The metallacycle is more stable than the acyclic complex and whereas Cp2Ti"Bu2 decomposes via the expected (3-1I elimination pathway to produce butenes and butane, the thermal decomposition products of 1 are ethylene and 1-butene. In addition, the metallacycle is observed to be significantly more reactive towards CO than Cp2Ti"Bu2 Reaction of 1 with carbon monoxide at —55 °C yields the titanium acyl species, based on infrared data, which then rapidly converts to cyclopentanone at 0 °C (Scheme l).13... 

Acetic Acid.—Besides hydrogen, carbon mon- and dioxides, Maquenne 3 also obtained methane, ethylene, and acetylene. With increasing pressure he found an increase in hydrogen and carbon monoxide, a decrease in-carbonic acid and hydrocarbons. Hemptinne observed similar results with his experimental arrangement. He accepts the following as the primary decomposition process, corresponding to that of the alcohols ... 

Tucker and Moody9 were unable to prepare the almost pure carbide described by Moissan, and attributed their failure to the very small temperature-interval between the formation and the decomposition of the substance. The carbide is also formed by the interaction of lithium and any of the allotropic modifications of carbon in vacuum at dull red heat and by the combination of the metal with carbon monoxide or dioxide, or with ethylene or acetylene, an impure product is obtained.10... 

Some dense inorganic membranes made of metals and metal oxides are oxygen specific. Notable ones include silver, zirconia stabilized by yttria or calcia, lead oxide, perovskite-type oxides and some mixed oxides such as yttria stabilized titania-zirconia. Their usage as a membrane reactor is profiled in Table 8.4 for a number of reactions decomposition of carbon dioxide to form carbon monoxide and oxygen, oxidation of ammonia to nitrogen and nitrous oxide, oxidation of methane to syngas and oxidative coupling of methane to form C2 hydrocarbons, and oxidation of other hydrocarbons such as ethylene, methanol, ethanol, propylene and butene. 

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