Light hydrocarbons partial oxidation

We have summarized below recent results concerning spectroscopic / flow reactor investigations of hydrocarbons partial and total oxidation on different transition metal oxide catalysts. The aim of this study is to have more information on the mechanisms of the catalytic activity of transition metal oxides, to better establish selective and total oxidation ways at the catalyst surface, and to search for partial oxidation products from light alkane conversion. 

CAR [Combined autothermal reforming] A "reforming process for making "syngas from light hydrocarbons, in which the heat is provided by partial oxidation in a section of the reactor. Developed by Uhde and commercialized at an oil refinery at Strazske, Slovakia, in 1991. 

The partial oxidation method is normally used for heavier feedstocks, everything from naphtha to residual fuel, in those places where natural gas or light hydrocarbons (ethane, propane, or butane) are not readily available. 

Synthesis gas generation Process in which light hydrocarbons are partially oxidized over a catalyst at about 875 K with oxygen and the carbon monoxide is shifted with steam to produce CO and H. ... 

In the past, coal or heavy hydrocarbon feedstock ammonia plants were not economically competitive with plants where the feedstocks were light hydrocarbons (natural gas to naphtha). Because of changing economics, however, plants that can handle heavy hydrocarbon feedstock are now attracting increasing attention- In addition, the continuous development and improvement of partial oxidation processes at higher pressure have allowed reductions in equipment size and cost. Therefore, the alternate feedback ammonia plants based on a partial oxidation process may become economically competitive in the near future. 

The continental biosphere is a large source of hydrocarbons. Quantification of these sources in toms of geophysical (e.g. temperature, humidity, light levels) and biogeochemical (soil physical and chemical properties, land use) parameters is much needed for inclusion in atmospheric models. The hydrocarbon oxidation mechanisms in the atmosphere should also be better understood, so that formation of ozone, carbon monoxide, partially oxidized gaseous hydrocarbons, and organic aerosol can be better quantified. The formation of organic aerosol from hydrocarbon precursors and then-capability to serve as cloud condensation nuclei are issues which need to be studied in depth. 

Process hydrogen is produced by steam reforming light hydrocarbon gases. An alternative method for hydrogen production is partial oxidation of the heavy vacuum bottoms stream or of coal. 

There are basically three processes in usage today for the production of hydrogen or ammonia synthesis gas Steam Reforming for the conversion of light hydrocarbons from natural gas to straight run naphthas Partial Oxidation for heavy hydrocarbons and coal and Electrolysis of Water. 

Coal Feed. As in the case of steam reforming versus partial oxidation, a plant based on use of coal as feedstock is expected to cost more than one based on partial oxidation because of additional equipment requirements, particularly with regard to coal handling operations, gasification and raw gas treatment. Despite these cost differences, coal based plants can be justified if the cost of coal is sufficiently low, that is, relative to light or heavy hydrocarbons. The approximate investment for a coal-based plant appears to be about 2.0 times that for a natural gas plant.The investment is about 33% more for a fuel oil... 

The raw synthesis gases from partial oxidation of heavy hydrocarbons and coal differ mainly in two aspects from that produced from light hydrocarbons by steam reforming. First, depending on the feedstock composition, the gas may contain a rather high amount of sulfur compounds (mainly H2S with smaller quantities of COS) second, the CO content is much higher, in some cases in excess of 50%. The sulfur compounds (Section 4.3.1.4) can be removed ahead of the shift conversion to give a sulfur-free gas suitable for the classical iron HTS catalyst. In another process variant the sulfur compounds are removed after shift conversion at lower concentration because of dilution by C02. The standard iron catalyst can tolerate only a limited amount of sulfur compounds. With a sulfur concentration in the feed >100 ppm sulfur will be stored as iron sulfide (Eq. 87) ... 

With the exception of the Koppers-Totzek coal gasification process, which operates at near atmospheric pressure, all modern gasification processes operate at elevated pressure. Steam reforming of light hydrocarbons at 30-40 bar and partial oxidation of heavy hydrocarbons at 40-90 bar are generally used. 

A hydrocarbon feed (e.g., methane, light and heavy liquids or petroleum coke and coal) is converted to synthesis gas (mostly CO and H2 with small amounts of acid gases C02 H2S and COS as impurities) in the partial oxidation process by reacting with steam and oxygen at a temperature of 1,370-1,540X. By cooling off the hot gas, CO is converted with the steam to form C02andH2. 

Under idealized conditions, the primary products of biomass gasification by pyrolysis, partial oxidation, or reforming are essentially the same The carbon oxides and hydrogen are formed. Methane and light hydrocarbon gases are also formed under certain conditions. Using cellulose as a representative feedstock, examples of some stoichiometries are illustrated by these equations ... 

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