Catalytic reforming feeds

Catalytic reformer feeds are saturated (i.e., not olefinic) materials in the majority of cases that feed may be a straight-run naphtha but in others by-product low-octane naphtha (e.g., coker naphtha) can be processed after treatment to remove olefins and other contaminants. Hydrocracker naphtha that contains substantial quantities of naphthenes is also a suitable feed. 

An example of the need for sharpness control might be the benefit of removing dicyclic hydrocarbons boiling at 400° F or above from the catalytic reforming feed, while maintaining naphtha yield. These dicyclics are known to foul platinum reforming catalysts with carbon. 

Many hydrotreaters are stay-in-business investments, so it s diffieult to quantify their upgrade value, which is the value of products minus costs -labor, materials (liquid feed, hydrogen, catalysts and chemicals), utilities, maintenance, and investment amortization. In some plants, the refinery planning LP assigns equal value to treated and imtreated naphtha, and even to treated and untreated distillates. This reflects the underlying assumption that the increase in value across a hydrotreater is equal to the cost of running the unit, i.e., the upgrade value is zero. In other LPs, the NHT that pretreats catalytic reformer feed is lumped in with the reformer. Certainly, if a key naphtha or distillate hydrotreater shuts down, ihe refinery may have to run at reduced rate, but that can be said of most units. 

Catalytic Reformer Feed for Motor Gasoline Production... 

Tordcoiogy. Inh. may cause dizziness, headache, drowsiness, nausea, unconsciousness contact may cause dry skin, eye redness Ing. may cause cough, diarrhea, sore throat, vomiting if aspirated, may cause chem. pneumonitis Environmental Toxic to aquatic organisms prevent entry into sewers Precaution Flamm. explosive limits in air 0.7-6.0 vol.% may forni explosive vapor/ air mixts. above 40 C reacts with strong oxidants, causing fire/explosion hazard Uses Solvent catalytic reformer feed flow aid food-contact paper, robber articles ... 

For the refiner, the reduction in benzene concentration to 3% is not a major problem it is achieved by adjusting the initial point of the feed to the catalytic reformers and thereby limiting the amount of benzene precursors such as cyclohexane and Cg paraffins. Further than 3% benzene, the constraints become very severe and can even imply using specific processes alkylation of benzene to substituted aromatics, separation, etc. 

Butanes are recovered from raw natural gas and from petroleum refinery streams that result from catalytic cracking, catalytic reforming, and other refinery operations. The most common separation techniques are based on a vapor—Hquid, two-phase system by which Hquid butane is recovered from the feed gas. 

The predominant feeds for reforming are straight-mn naphthas from cmde stills. Naphthas from catalyst crackers and naphthas from code stills are also used. Typical compositions are summarized in Table 5. Typical operating conditions for catalytic reforming are 1.135—3.548 MPa (150—500 psi),... 

C, 0.356—1.069 m H2/L (2000—6000 fU/bbl) of Hquid feed, and a space velocity (wt feed per wt catalyst) of 1—5 h. Operation of reformers at low pressure, high temperature, and low hydrogen recycle rates favors the kinetics and the thermodynamics for aromatics production and reduces operating costs. However, all three of these factors, which tend to increase coking, increase the deactivation rate of the catalyst therefore, operating conditions are a compromise. More detailed treatment of the catalysis and chemistry of catalytic reforming is available (33—35). Typical reformate compositions are shown in Table 6. 

Catalytic Reforming. Worldwide, approximately 30% of commercial benzene is produced by catalytic reforming, a process ia which aromatic molecules are produced from the dehydrogenation of cycloparaffins, dehydroisomerization of alkyl cyclopentanes, and the cycHzation and subsequent dehydrogenation of paraffins (36). The feed to the catalytic reformer may be a straight-mn, hydrocracked, or thermally cracked naphtha fraction ia the... 

Hydrofining is applied to virgin naphthas mainly in the form of a pretreatment step for the feed to catalytic reformers (Powerforming). Sulfur levels of 5 parts per million (ppm) or less are required to avoid deactivation of the platinum reforming catalyst. 

In order to produce more paraxylene than is available in catalytic reformate, a xylenes-isomerization plant is sometimes included in the processing scheme. The isomerization step uses the effluent (filtrate) from the paraxylene crystallization step as feed. The filtrate contains about 7-9 percent of paraxylene. The isomerization unit brings the concentration back to its equilibrium value of about 20 percent. 

Liquid solvents are used to extract either desirable or undesirable compounds from a liquid mixture. Solvent extraction processes use a liquid solvent that has a high solvolytic power for certain compounds in the feed mixture. For example, ethylene glycol has a greater affinity for aromatic hydrocarbons and extracts them preferentially from a reformate mixture (a liquid paraffinic and aromatic product from catalytic reforming). The raffinate, which is mainly paraffins, is freed from traces of ethylene glycol by distillation. Other solvents that could be used for this purpose are liquid sulfur dioxide and sulfolane (tetramethylene sulfone). 

Reduce harmful impurities in petroleum fractions and residues to control pollution and to avoid poisoning certain processing catalysts. For example, hydrotreatment of naphtha feeds to catalytic reformers is essential because sulfur and nitrogen impurities poison the catalyst. 

The feed to a catalytic reformer is normally a heavy naphtha fraction produced from atmospheric distillation units. Naphtha from other sources such as those produced from cracking and delayed coking may also be used. Before using naphtha as feed for a catalytic reforming unit, it must be hydrotreated to saturate the olefins and to hydrodesulfurize... 

Normally, catalytic reformers operate at approximately 500-525°C and 100-300 psig, and a liquid hourly space velocity range of 2-4 hr" Liquid hourly space velocity (LHSV) is an important operation parameter expressed as the volume of hydrocarbon feed per hour per unit volume of the catalyst. Operating at lower LHSV gives the feed more contact with the catalyst. 

The process consists of a reactor section, continuous catalyst regeneration unit (CCR), and product recovery section. Stacked radial-flow reactors are used to minimize pressure drop and to facilitate catalyst recirculation to and from the CCR. The reactor feed consists solely of LPG plus the recycle of unconverted feed components no hydrogen is recycled. The liquid product contains about 92 wt% benzene, toluene, and xylenes (BTX) (Figure 6-7), with a balance of Cg aromatics and a low nonaromatic content. Therefore, the product could be used directly for the recovery of benzene by fractional distillation (without the extraction step needed in catalytic reforming). 

I. Catalytic reformer, combined feed/effluent exchanger shell plate postweld heat treated at 1250°F. 

K. Catalytic reformer combined feed piping welds and base metal postweld heat treatment. 

Methanol production, where CO is added as additive, is very a well-known reaction. The production is carried out in two steps. The first step is to convert the feedstock natural gas into a synthesis gas stream consisting of CO, CO2, H20 and hydrogen. This is usually accomplished by the catalytic reforming of feed gas and steam. The second step is the catalytic synthesis of methanol from the synthesis gas. If an external source of C02 is available, the excess hydrogen can be consumed and converted to additional methanol. 

The bulk of the naphtha was hydrotreated and catalytically reformed over a chlorided Pt/Al203-based catalyst to produce an aromatic motor gasoline. However, the hydrotreated Fischer-Tropsch naphtha is a poor feed for standard catalytic reforming on account of its high linear hydrocarbon content (>75%).37 In order to limit liquid yield loss, typical operation resulted in a reformate with quite low octane value (Table 18.10). Higher octane reformate could be produced, but at the expense of significant liquid yield loss. 

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