Showing papers on "Partial oxidation published in 1986"

Partial Oxidation of Methane

Abstract: Partial oxidation is a widely used process to convert hydrocarbons and alcohols to valuable oxygen-containing chemicals. Although methane is the simplest hydrocarbon which gives formaldehyde and methanol as partial oxidation products, the direct utilization of these reactions for the manufacture of formaldehyde and methanol has remained extremely difficult. During the 1940s, two processes for the conversion of methane to formaldehyde were developed in Germany [l]. The first process used NO as a catalyst, and a commercial plant using this process was known to have been in operation in Copsa Mica in Romania. The second process used a combination of ozone and barium peroxide as the catalyst. In the current industrial practice, however, methane is converted to HCHO through a three-step process involving high temperature steam reforming, low pressure methanol synthesis, and oxidative dehydrogenation of methanol to formaldehyde, as shown by Unlike steam reforming, direct oxidation does not require ener...

Photooxidation of methanol using vanadium pentoxide/titanium dioxide and molybdenum trioxide/titanium dioxide surface oxide monolayer catalysts

Abstract: The authors have compared the conversion and selectivity obtained using 7 wt% V/sub 2/O/sub 5//TiO/sub 2/ and 4.0 wt% MoO/sub 3//TiO/sub 2/ catalysts for the partial oxidation of CH/sub 3/OH, as a function of reaction temperature and illumination. The thermally controlled reaction is faster and slightly less selective to CH/sub 2/O on the vanadia/TiO/sub 2/ catalyst. In contrast, the incremental photoassisted reaction rate is much lower on the vanadia catalyst than on the molybdena catalyst, which in turn is less photoactive than pure TiO/sub 2/. The observed sequence of the relative photoactivities varies inversely with the concentration of V or Mo cations in the surface oxide monolayers, which suggests that the photoassisted alkoxy dehydrogenation process occurs primarily at exposed TiO/sub 2/ surface sites.

SYNTHESIS OF ETHYLENE BY PARTIAL OXIDATION OF METHANE OVER THE OXIDES OF TRANSITION ELEMENTS WITH LiCl

Abstract: The synthesis of ethylene directly from methane has been tested in the presence of oxygen over the LiCl-added transition metal oxides. The oxides of Mn and Ni with LiCl produced ethylene with high selectivity (ca. 60%) and yield (ca. 27%) under the following experimental conditions: T=1023 K, P(CH4)/P(O2)=2/1, P(CH4)=5.1 kPa, and W/F=600–1200 g l−1s.

Partial oxidation process with magnetic separation of the ground slag

Abstract: Synthesis gas is produced by the partial oxidation of a feedstock comprising petroleum coke and/or heavy liquid hydrocarbon fuel containing sulfur and having an ash that contains nickel, vanadium and silicon. An iron-containing or an iron and calcium-containing additive is introduced into the reaction zone along with the feed. The additive combines with at least a portion of the iron and nickel constituents and sulfur found in the feedstock to produce a liquid phase washing agent that collects and transports at least a portion of the vanadium-containing oxide laths and spinels and other ash components out the reaction zone. Slag and other particulate matter is separated from the effluent gas stream and ground to produce a heterogeneous mixture of magnetic and non-magnetic solid particles. The particles have various degrees of magnetic susceptibility and are thereby separated into the following three separate portions of magnetic particles: (1) particles of an Fe-Ni alloy, and a minor amount of magnetite particles; (2) particles of an oxysulfide phase of iron and nickel, a minor amount of particles of vanadium compounds, and particles of iron silicate and calcium silicate; and (3) particles of vanadium-containing spinels, and particles of metal silicates. The first and third portions are sent to a metal refiner to recover nickel and vanadium respectively. The second portion of magnetic particles having an increased Fe/V wt. ratio is recycled through the gasifier.

Catalytic hydrogen generator for use with methanol

Abstract: A catalytic hydrogen generator which generates hydrogen by the partial oxidation of methanol by oxygen (usually supplied as air) which comprises a gas permeable catalyst system having an upstream zone (2) filled with a copper catalyst supported on a refractory support (3) (for example silica or silicate granules) and a downstream zone (4) filled with a mixture of a similar supported copper catalyst and a platinum or palladium catalyst supported on a similar refractory support (5b). A mixture of methanol and oxygen is fed to the upstream zone and initially permeates through to the downstream zone where spontaneous oxidation of the methanol is initiated raising the temperature of the system to a level at which partial oxidation of methanol in the presence of the copper catalyst in the upstream zone (2) commences and produces hydrogen.

Producing ammonia synthesis gas

Abstract: Production of ammonia synthesis gas by partial oxidation of a hydrocarbon feedstock, using air, oxygen enriched air, or oxygen depleted air, in admixture with steam, followed by shift and the removal of the excess of nitrogen, and also impurities such as carbon oxides and methane, by pressure swing adsorption (PSA). The PSA waste gas is combusted and used to heat the air and/or steam prior to the use thereof in the partial oxidation.

The potential for methanol production from natural gas by direct catalytic partial oxidation

Abstract: An evaluation of methanol production from natural gas by the conventional synthesis process shows that gas feedstock and capital charges are the dominant components of the methanol cost. Small but significant reductions In product cost can be made by increasing the conversion per pass and heat recovery from the synthesis reactor. However, the overall performance of the process is limited by the high cost and thermal Inefficiencies associated with the steam reforming step used to produce the synthesis gas. Catalytic partial oxidation (CPO) of methane directly to methanol has a potential advantage over the conventional process in that it eliminates the need for steam reforming. However, although considerable research has been conducted on CPO, no commercially viable process has yet been developed. An economic evaluation of a conceptual process for methanol production by CPO has been carried out assuming pure oxygen is used as oxidant. Results show that CPO has potential for reducing the coat of met...

New Multi-Sulfur 1,2-Dithiolene Complexes. Preparation, Structure, and Electrochemical Properties

Abstract: New multi-sulfur 1,2-dithiolene complexes in which the 1,2-dithiolene moiety is extended by incorporating heterorings have been prepared and characterized by IR spectroscopy, X-ray diffraction method, and cyclic voltammetry. Partial oxidation of these complexes are expected to provide the multi-dimensional molecular conductors. Electrochemical properties of these complexes are compared with those of the dmit-complexes (dmit=2-thioxo-1,3-dithiole-4,5-dithiolate).

Selective synthesis of ethylene by partial oxidation of methane over LiCl–Sm2O3

Abstract: Methane is partially oxidised over LiCl–Sm2O3 catalyst to give C2-compounds (ethylene and ethane) in 7.2–19.9% C2-yield at 750 °C, with a high C2H4:C2H6 ratio.

Vessel for the generation of synthesis gas

Abstract: A vessel for the generation of synthesis gas at a high pressure, using hydrocarbons, includes a catalytic endothermic reforming section with a plurality of reformer tubes heated externally and filled with a catalyst, and a mixture of hydrocarbons and steam entering the reformer tubes which are positioned by a common plate. The reforming gas generated in the tubes flows from the tubed section into a partial oxidation section which has a larger diameter than the tubed section and the shape of a pressure vessel closed at one end, the free ends of the reformer tubes penetrating into the partial oxidation section, and in which inlet gas such as additional hydrocarbons and oxygen or oxygen-rich gas are mixed with the reforming gas. A plurality of inlet devices for the inlet gas are positioned in the cylindrical shell of the partial oxidation section with the axes of the gas flow streams being inclined away from the radial. The inlet devices are spaced a predetermined distance from the outlet end of the reformer tubes such that a rotary gas vortex is produced and the product gas stream flows through the outer section of the chamber, heats the reformer tubes and leaves the reforming section via an outlet nozzle.

A wet chemical method for the determination of free carbon in boron carbide, silicon carbide and mixtures thereof

Abstract: Since known methods for the quantitative determination of free carbon in boron carbide were found to be unsatisfactory, a new method was developed based on a modified Meerson-Samsonov technique, i.e. wet chemical dissolution in hot chromic-sulphuric-iodic acid mixtures. All free carbon, and usually a small amount of combined carbon, is oxidized to carbon dioxide, which is measured coulometrically as a function of the oxidation time. From the CO2 concentration versus time curve plotted, the free carbon content can be calculated; partial oxidation of combined carbon is accounted for by graphical extrapolation. The method was successfully applied also to SiC and further to dense ternary composites made from SiC, boron carbide and carbon. Especially in the case of submicrometre-sized particle carbide powders the new free carbon analyser proved to be very useful.

Partial oxidation of propene by active oxygen generated electrochemically on gold through yttria-stabilized zirconia

Abstract: Propene was partially oxidized to acrylaldehyde by oxygen species generated electrochemically on an inert gold film via yttria-stabilized zirconia at 450 °C.

Apparatus for the production of synthesis gas

Abstract: In an apparatus for producing synthesis gas at an elevated pressure of hydrocarbons, particularly natural gas, naphtha and / or refinery gas in a catalytic endothermic reforming portion (1) having a cylindrical pressure vessel, and a multiplicity of externally heated catalyst-filled reformer tubes (6), wherein in held in a tube sheet plate (25) reformer tube (6) entering a mixture of hydrocarbons and steam and exiting a reforming gas from them and, in a subsequent in diameter to the aforementioned reforming enlarged partial oxidation section (2) in pressure vessel form a closed-end, in the extend the reformer tube (6) with the free ends (8) and are introduced into the the reformate from the reformer tubes, as well as additional hydrocarbons and oxygen or oxygen-containing gas, to a solution to be found with the thermal reactions operationally safe and effectively vol lstandig proceed. This is achieved in that a plurality of feeder means (10) for hydrocarbons and / or oxygen or oxygen-containing gas are arranged in the cylinder wall of the partial oxidation section (12) whose center axes are aligned at an angle to the radial beam and parallel inclined to the radial plane and whose spacing is dimensioned to the outflow ends of the reformer tubes so that (2) is formed a rotating loop flow of the gases in the free partial oxidation part and flows, the product gas outside, in order then the reformer tubes to flow around to heat and the reforming part (1) through the outlet to leave (19).

Oxidation studies of selected lanthanides in acetonitrile

Abstract: Cerium(III), praseodymium(III) and terbium(III) nitrates were subjected to prolonged (3–24 h) ozonolysis in the presence of oxygen donor ligands in acetonitrile at 70 °C in an effort to stabilize the IV oxidation state of these metal ions. From spectroscopic and electrochemical studies it was determined that the lanthanides were oxidized to the IV oxidation state. Acetonitrile solutions of cerium(III) nitrate and cerium(III) chloride in the presence of triphenylarsine oxide (TPAsO) were also subjected to prolonged bubbling with air or oxygen at 70 °C. It was determined from spectroscopic studies that at least partial oxidation to the IV oxidation state of cerium occurred.

Partial oxidation of vanadium-containing heavy liquid hydrocarbonaceous and solid carbonaceous fuels

Abstract: Process for the production of gaseous mixtures comprising H2 +CO eg synthesis gas, reducing gas, or fuel gas by the partial oxidation of a vanadium-containing liquid hydrocarbonaceous fuel, solid carbonaceous fuel, or mixtures thereof in a free-flow vertical refractory lined gas generator The feed mixture to the gas generator comprises (i) a vanadium-containing fuel; (ii) supplemental iron-containing ash fusion temperature reducing agent; and (iii) at least a portion of the remainder of the iron-containing slag after separation of an enriched vanadium-containing coarse slag fraction The coarse slag fraction has a decreased Fe/V weight ratio and is formed by depositing a portion of the slag entrained in the hot raw effluent gas stream from the partial oxidation reaction zone on the walls of a slag separation chamber located between the bottom discharge outlet in the reaction zone and the effluent gas quench tank located at the bottom of the gas generator It is economically advantageous to recover by-product vanadium from the coarse slag fraction in a metal refining plant

Coal gasification process

Abstract: Low sulfur, iron and calcium containing solid carbonaceous fuel having a high melting point ash is mixed with a sufficient amount of iron sulfide containing material or supplemental iron and sulfur containing reactant materials that react in the reaction zone to produce iron and sulfur containing compounds. The mixture of materials is reacted in a free-flow gasifier by partial oxidation to produce a raw gas stream of synthesis gas, reducing gas or fuel gas, containing entrained particulate matter including molten slag. By the process, sufficient iron and sulfur are in the reaction zone so that the melting point of the fuel ash is decreased, and the mole ratio H2 S/H2 +CO in the raw gas stream is greater than 0.01. Further, the amount of iron in the molten ash is greater than 10.0 wt. %, and preferably at least 14 wt. % of the molten ash. By this means, the fluid temperature of the molten ash entrained in the raw gas stream is reduced at least 100° F. less than the fluid temperature of the fuel ash without the addition of iron and sulfur, and the gasifier may be operated in the molten slagging mode at a lower temperature. Further, coal wash tailings containing iron sulfides may be disposed of as a portion of the feed to the gasifier in an environmentally acceptable manner; and useful by-product sulfur may be recovered.

Partial oxidation of solid carbonaceous fuel-water slurries

Abstract: Aqueous slurries of solid carbonaceous fuel having an increased reactivity of the solid material are produced by maintaining the solid carbonaceous fuel-water slurry at a temperature in the range of about 300° to 650° F. and a pressure in the range of about 100 to 3500 psia and sufficient to maintain the H 2 O in the slurry in liquid phase; at substantially constant temperature depressurizing said slurry to a pressure in the range of about above atmospheric to 250 psia above that in the reaction zone of a partial oxidation gas generator, thereby partially vaporizing the water in the slurry and producing steam. After depressurizing, the slurry is cooled so that the solid particles drop in temperature about 2° F. to 10° F. and the water in the slurry drops in temperature about 100° F. to about 200° F. the upgraded solid carbonaceous fuel-water slurry is then introduced into the reaction zone of the gas generator with substantially no further charge in pressure and/or temperature except for that resulting from ordinary pressure and/or heat losses in the lines. By the partial oxidation of the upgraded stream of solid carbonaceous fuel-water slurry with a free-oxygen containing gas in the gas generator, synthesis gas, reducing gas, or fuel gas is produced with a greater efficiency.