Steam hydrocarbon reforming naphtha

In Europe, synthesis gas is mainly produced by steam reforming naphtha. Because naphtha is a mixture of hydrocarbons ranging approximately from C5-C10, the steam reforming reaction may be represented using n-heptane ... 

Steam-naphtha reforming a process that is essentially similar in nature to the steam-methane reforming process (q.v.) but which used higher molecular weight hydrocarbons as the feedstock. 

Description Natural gas or another hydrocarbon feedstock is compressed (if required), desulfurized, mixed with steam and then converted into synthesis gas. The reforming section comprises a prereformer (optional, but gives particular benefits when the feedstock is higher hydrocarbons or naphtha), a fired tubular reformer and a secondary reformer, where process air is added. The amount of air is adjusted to obtain an H2/N2 ratio of 3.0 as required by the ammonia synthesis reaction. The tubular steam reformer is Topsoe s proprietary side-wall-fired design. After the reforming section, the synthesis gas undergoes high- and low-temperature shift conversion, carbon dioxide removal and methanation. 

In a manner similar to FCC, fluidized beds have also been utilized for catalytic reforming of straight-chain naphtha hydrocarbon compounds into branched-chain compounds of higher octane number. While most steam reforming of natural gas to produce hydrogen has been carried out in fixed-bed reactors, there have also been periodic efforts to conduct steam methane reforming (SMR) in fluidized beds. 

On many crude units, steam stripping of naphtha, kerosene, and furnace oil appears adequate. On the other hand, stripping of FCCU feed is frequently poor. Figure 1-5 shows the effect of stripping. Hydrocarbons boiling below 500 F belong in naphtha reformer feed or kerosene, not in the FCCU charge. 

Steam Reforming. In steam reforming, light hydrocarbon feeds ranging from natural gas to straight mn naphthas are converted to synthesis gas (H2, CO, CO2) by reaction with steam (qv) over a catalyst in a primary reformer furnace. This process is usually operated at 800—870°C and 2.17—2.86... 

Naphtha desulfurization is conducted in the vapor phase as described for natural gas. Raw naphtha is preheated and vaporized in a separate furnace. If the sulfur content of the naphtha is very high, after Co—Mo hydrotreating, the naphtha is condensed, H2S is stripped out, and the residual H2S is adsorbed on ZnO. The primary reformer operates at conditions similar to those used with natural gas feed. The nickel catalyst, however, requires a promoter such as potassium in order to avoid carbon deposition at the practical levels of steam-to-carbon ratios of 3.5—5.0. Deposition of carbon from hydrocarbons cracking on the particles of the catalyst reduces the activity of the catalyst for the reforming and results in local uneven heating of the reformer tubes because the firing heat is not removed by the reforming reaction. 

Tubular Fixed-Bed Reactors. Bundles of downflow reactor tubes filled with catalyst and surrounded by heat-transfer media are tubular fixed-bed reactors. Such reactors are used most notably in steam reforming and phthaUc anhydride manufacture. Steam reforming is the reaction of light hydrocarbons, preferably natural gas or naphthas, with steam over a nickel-supported catalyst to form synthesis gas, which is primarily and CO with some CO2 and CH. Additional conversion to the primary products can be obtained by iron oxide-catalyzed water gas shift reactions, but these are carried out ia large-diameter, fixed-bed reactors rather than ia small-diameter tubes (65). The physical arrangement of a multitubular steam reformer ia a box-shaped furnace has been described (1). 

Steam Reforming Processes. In the steam reforming process, light hydrocarbon feedstocks (qv), such as natural gas, Hquefied petroleum gas, and naphtha, or in some cases heavier distillate oils are purified of sulfur compounds (see Sulfurremoval and recovery). These then react with steam in the presence of a nickel-containing catalyst to produce a mixture of hydrogen, methane, and carbon oxides. Essentially total decomposition of compounds containing more than one carbon atom per molecule is obtained (see Ammonia Hydrogen Petroleum). 

In Europe naphtha is the preferred feedstock for the production of synthesis gas, which is used to synthesize methanol and ammonia (Chapter 4). Another important role for naphtha is its use as a feedstock for steam cracking units for light olefins production (Chapter 3). Heavy naphtha, on the other hand, is a major feedstock for catalytic reforming. The product reformate containing a high percentage of Ce-Cg aromatic hydrocarbons is used to make gasoline. Reformates are also extracted to separate the aromatics as intermediates for petrochemicals. 

Steam reforming was developed in Germany at the beginning of the 20th century, to produce hydrogen for ammonia synthesis, and was further introduced in the 1930s when natural gas and other hydrocarbon feedstocks such as naphtha became available on a large scale. 

Most industrial hydrogen is manufactured by the following hydrocarbon-based oxidative processes steam reforming of light hydrocarbons (e.g., NG and naphtha), POx of heavy oil fractions, and ATR. Each of these technological approaches has numerous modifications depending on the type of feedstock, reactor design, heat input options, by-product treatment,... 

RKN A process for making hydrogen from hydrocarbon gases (from natural gas to naphtha) by steam reforming. Developed by Haldor Topsoe in the 1960s as of 1975, 24 plants were operating. 

Hydrocarbon feedstocks for steam reformers include natural gas, refinery gas, propane, LPG and butane. Naphtha feedstocks with boiling points up to about 430°F can also be used. The ideal fuels for steam reformers are light hydrocarbons such as natural gas and refinery gas, although distillate fuels are also used. Residual fuels are not used since they contain metals that can damage reformer tubes. 

Fuel Hydrogen for PAFC power plants will typically be produced from conversion of a wide variety of primary fuels such as CH4 (e.g., natural gas), petroleum products (e.g., naphtha), coal liquids (e.g., CH3OH) or coal gases. Besides H2, CO and CO2 are also produced during conversion of these fuels (unreacted hydrocarbons are also present). These reformed fuels contain low levels of CO (after steam reforming and shift conversion reactions in the fuel processor) which cause anode poisoning in PAFCs. The CO2 and unreacted hydrocarbons (e.g., CH4) are electrochemically inert and act as diluents. Because the anode reaction is nearly reversible, the fuel... 

In addition to natural gas, steam reformers can be used on light hydrocarbons such as butane and propane and on naphtha with a special catalyst. Steam reforming reactions are highly endothermic and need a significant heat source. Often the residual fuel exiting the fuel cell is burned to supply this requirement. Fuels are typically reformed at temperatures of 760 to 980°C (1,400 to 1,800°F). 

Reforming, In refining, a catalytic process in which naphtha molecules are cracked, rearranged, and/or recombined for the purpose of increasing the octane number of the naphtha. Reforming is also the process of converting hydrocarbons and steam to synthesis gas (carbon monoxide and hydrogen). 

Hydrogen production by partial oxidation is similar to production by catalytic steam reforming. The process basically involves the conversion of steam, oxygen and hydrocarbons to hydrogen and carbon oxides. The process proceeds at moderately high pressures with or without a catalyst depending on the feedstock and process selected. The catalytic POX, which occurs at about 865 K, will work with feedstock ranging from methane to naphtha. The non-catalytic POX, which occurs... 

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