JPH10316974A - Catalytic reforming process for hydrocarbon and method for inhibiting coking - Google Patents

Abstract

PROBLEM TO BE SOLVED: To inhibit the formation of coke in a catalytic reforming apparatus. SOLUTION: In a process for catalytically reforming a hydrocarbon, the formation of coke due to the catalytic action of a metal, esp. iron, in a catalytic reforming apparatus can be inhibited by incorporating naphthalene in an amt. of 0.05-10 wt.%, pref. 0.05-1 wt.%, (based on the hydrocarbon) into a raw material feed comprising the hydrocarbon and hydrogen.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for suppressing coking in an apparatus for performing catalytic reforming of hydrocarbons such as naphtha and a straight-run gasoline feedstock in the presence of a catalyst.

[0002]

BACKGROUND OF THE INVENTION Contact reforming is a process used in the petroleum industry to improve the octane number of naphtha and straight run gasoline. Contact reforming is
Dehydrogenation of cyclohexanes and the like and dehydroisomerization of alkylcyclopentanes and the like to produce aromatic compounds; n
-Isomerization of paraffins; isomerization of alkylcycloparaffins; and reactions of hydrocarbons such as hydrocracking of paraffins to produce gases and unavoidable coke. Coke generated by hydrocracking accumulates on the catalyst. Basically, coking means that heavy components in feed oil or heavy components generated by partial polymerization in feed oil adhere to the walls of equipment and are exposed to higher temperatures for longer periods of time. It grows and becomes coke.

[0003] In catalytic reforming, a bifunctional catalyst in which platinum is supported on a porous inorganic oxide support such as alumina is used as a typical catalyst. Elements such as rhenium, tin, iridium, and germanium are added to platinum as needed. As a porous inorganic oxide support other than alumina, bentonite, terra alba, diatomaceous earth, zeolite, silica, activated carbon, magnesia, zirconia, thoria and the like are used.

[0004] Commercial reforming processes are typically performed in either continuous or fixed bed reactors. Fixed bed reactors are usually used in semi-regenerative mode, while circulating and moving bed reactors are used in continuous reforming.

[0005] When a fixed bed reactor is used, the regeneration operation of the catalyst must be carried out periodically. The coke that has accumulated in the reactor is removed in a combustion step during catalyst regeneration. Also, in many cases, fixed bed reactors have high hydrogen / oil ratios and are operated under relatively high reaction pressures, such as 700-3,000 kPa-G, so that coke grows in the reactor. The speed of doing was also low.

On the other hand, in the moving bed type reactor, the reactor and the regenerator are separate, so that coke is not burned in the reactor. However, in many cases, the coke grown in the reactor tends to accumulate because the hydrogen / oil ratio is lower and the reactor is operated under a relatively low reaction pressure such as 300 to 1000 kPa-G.

[0007]

SUMMARY OF THE INVENTION Contact reforming,
In particular, in the continuous reforming-type contact reforming, in recent years, the conversion to aromatic hydrocarbons has been improved by significantly lowering the reaction pressure. On the other hand, due to a decrease in pressure, particularly a decrease in hydrogen partial pressure, coke (mainly, metal-catalyzed coke) has been easily generated on a wall surface or the like in the reactor. This coke grows fast,
Due to the large voids, the mechanical strength is not very high.
However, this coke induces the growth of complex and highly crystallized coke, causing mechanical damage to the reactor,
In some cases, continuation of operation may be difficult due to blockage of the flow path.

An object of the present invention is to suppress the generation of coke inside a contact reforming apparatus.

[0009]

Means for Solving the Problems In view of the problems of the prior art, the present inventor has conducted intensive studies in order to suppress coking. As a result, in the contact reforming, the feedstock comprising hydrocarbons and hydrogen contained: By including the naphthalene in an amount of substantially 0.05 to 10% by weight with respect to the hydrocarbon, the inner wall or the inside of the contact reforming device can be
The inventors have found that metal-catalyzed coke generated by the catalytic action of metal, mainly iron, can be suppressed, and the present invention has been completed.

As described above, since the generation of coke can be suppressed inside the contact reforming apparatus, stable operation can be realized. Furthermore, the constraints imposed on the operating conditions during contact reforming in order to suppress the formation of coke,
It can be relaxed by the present invention, thereby producing more aromatic compounds and improving the octane number of gasoline.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in more detail. The present invention can be applied to a reforming system in which a plurality of reaction zones are arranged in series.
Preferably, a preheater is present between the reaction zones so that the temperature of the feed to each reaction zone can be controlled. Preferably, each reaction zone is located in a separate reactor. The invention relates to a system in which at least two reactors, preferably three to five reactors, are arranged in series. Some or all of the reactors may be fixed bed reactors or moving bed reactors, but moving bed reactors provide for coking in the reactor according to the present invention. High industrial value due to suppression.

In a multi-stage reaction zone reforming system, the catalyst composition may be different in different reforming zones, but generally the catalyst is the same in all reactors. However, the capacity of the catalyst usually differs between the reaction zones. The first reactor generally has a small amount of catalyst. This is because the feedstock is rapidly cooled by the highly endothermic reaction that occurs in the first reactor. If a large amount of catalyst is present in the first reactor, the lower portion of the catalyst bed will not be used effectively because the temperature of the feed in the downstream portion of the catalyst bed will be too low.

[0013] The temperature of each reaction zone may be the same or different. The final reaction zone generally has the highest average catalyst bed temperature. Each reactor pressure is almost the same except for the difference in the degree of pressure loss in the piping. It is particularly advantageous for a desired reforming reaction that the temperature and pressure be correlated with the liquid hourly space velocity (LHSV). With different catalyst loadings and different reaction zones, the space velocity of the individual reaction zones can vary considerably.

The hydrogen and feed rate, and the temperature and pressure
By adjusting the contact reforming process conditions,
The operation of the contact reforming device is started. Driving is
Adjustment of key process variables within the following ranges will continue at optimal reforming conditions.

[0015]

[Table 1]

Regeneration methods, whether continuous or batch, are well known in the art. Such a method generally involves the following several steps. That is, a step of contacting the catalyst with an oxygen-containing gas and burning off until substantially all of the carbon is removed, and then contacting the catalyst with an oxygen-containing gas to redisperse the platinum group, a halogen adjustment step, and a catalyst. An optional step of reducing the regenerated catalyst with hydrogen gas before returning to the reactor.

The content of naphthalene at the inlet of the reactor is 0.05 to 10% by weight, more preferably 0.0 to 10% by weight, based on the starting material hydrocarbon (for example, naphtha).
5 to 1% by weight. The naphthalene may be added to the raw material as long as it is upstream of the heating furnace of the contact reforming reactor. However, since naphthalene is a solid at normal temperature, naphthalene can be dissolved in a hydrocarbon such as naphtha in advance and then injected into the raw material. Further, as long as it contains naphthalene in an amount of substantially 0.05 to 10% by weight, a part of the reformate, which is a product of contact reforming, may be recycled as a raw material.

For example, the amount of naphthalene in naphtha depends on the distillation properties of naphtha, but is often 0.01% by weight.
It is as follows. In this range, failure is often caused by coke generated on the contact reforming device.
On the other hand, if the concentration of naphthalene exceeds 10% by weight, the processing amount of naphtha itself greatly decreases, which is economically disadvantageous.

The catalyst used in the reaction zone comprises a platinum group component supported on a porous solid support. Platinum is preferred as the platinum group component. Further, the porous solid carrier,
Preferably, it consists of a porous refractory inorganic oxide, for example alumina. The platinum group component is present in an amount of 0.01 to 3% by weight, preferably 0.01 to 1% by weight.

Other components than the platinum group components can be present on the porous solid support. Tin for example 0.01-
It is particularly preferred that it be present at 5% by weight, more preferably 0.01 to 2% by weight. Tin significantly improves the yields obtained with platinum-containing catalysts. In general, the reforming action of the catalyst is activated by the addition of halides, especially fluorides or chlorides. Halides provide a limited amount of acidity to the catalyst, which is advantageous for most reforming operations. The catalyst activated with halide has a total halide content of 0.1 to 3% by weight,
The preferred halide is chloride.

The catalyst used in the reaction zone may be, for example, a granular catalyst. This catalyst has, for example, a diameter
Generally, it is 1 to 3 mm, preferably 1.5 to 2 mm, but these values are not restrictive. The catalyst may have a spherical shape. The bulk density of the catalyst is generally 0.4 to
1, preferably 0.5 to 0.9, more particularly 0.55 to 0.
8, but these values are not restrictive.

The feed, that is, the charged raw material is about 27
It is a hydrocarbonaceous stream in the gasoline boiling range of ~ 220 ° C. Such raw materials include straight run naphtha, cracked naphtha,
Examples include, but are not limited to, those derived from both petroleum and synthetic sources, such as Fischer-Tropsch naphtha, coal-derived naphtha, and the like.

Typical feeds are hydrocarbons having from about 5 to 12, more preferably from about 5 to about 9 carbon atoms. Naphtha or petroleum fractions having a boiling point in the range of about 27-220 ° C, preferably about 50-190 ° C, contain carbon numbers in these ranges. Thus, a typical fraction is usually about 20-
About 80% by volume of both linear and branched paraffins in the range of about C5-C12; about 10-80% by volume of naphthenes in the range of about C6-C12; and about 5-20% by volume of about C6-C1
It contains desirable aromatics belonging to the range of 2.

Generally, although hydrogen is produced by catalytic reforming, hydrogen separated from the effluent of any reaction zone, usually the final reaction zone, is recycled to the first or subsequent reaction zone. Is common. Hydrogen can be mixed with the feed prior to contacting with the catalyst. Increasing the hydrogen / oil ratio can reduce coke production. Hydrogen is preferably introduced into the reforming reaction zone at a rate of 0.5 to 20 moles per mole of feed. Hydrogen may be a mixture with light hydrocarbon gas.

[0025]

EXAMPLES Next, examples of the present invention and comparative examples will be described, but the present invention is not limited to these examples.

The devices and catalysts employed in the examples or comparative examples of the present invention are as follows. (Reaction tube) The specification of the catalyst reaction tube is 605 mm in overall length, 10 mm in inner diameter, and made of SUS316. (Catalyst) 400 g of γ-alumina sieved to 10 to 16 mesh is collected and impregnated with water to fill the pores. Subsequently, 8.5 × 10 ⁻³ mol / 1 aqueous solution of chloroplatinic acid, 720 cc, and 1.7 × 10 ⁻² mol / 1 stannic chloride / 0.1 mol / 1 aqueous solution of hydrochloric acid, 600 cc, were added.
Evaporate to dryness in a sand bath. Then, after drying at 120 ° C. overnight, baking is performed at 400 ° C. for 1 hour. The BET specific surface area of the obtained catalyst was 200 m ² / g, and the pore volume was 0.8 cc / g by a nitrogen adsorption method. This is previously 500
The mixture was subjected to a hydrogen reduction treatment at 1 ° C. for 1 hour and used for a catalytic reaction test.

Table 2 shows the properties and composition of the desulfurized heavy naphtha.

[0028]

[Table 2]

(Evaluation of Amount of Coke Generated on Metal Sample) The ease of forming coke was evaluated by inserting a metal piece into a tubular reactor and increasing the weight of coke formed on the metal piece. In this evaluation device, the raw material hydrocarbon is supplied to the evaporator at a constant rate (for example, 3.1 g / h) by a micropump. The raw material preheated and vaporized by the evaporator is mixed with preheated hydrogen at a constant flow rate (for example, 21 ml / min) and sent to a reaction tube heated by an electric furnace. The reaction temperature was such that the metal specimen temperature was 570 ° C. to promote coking. Mild steel (SS400), which has no chromium oxide film formed on it and has direct iron exposure to the environment, was used to promote the formation of metal catalyzed coke.
The reaction pressure is also 100 kPa to promote the formation of coke.
-G. The reaction time was constant at 29 hours.

Example 1 A raw material in which 0.05% by weight of naphthalene was dissolved was passed through the desulfurized heavy naphtha to evaluate the amount of coke produced at a reaction pressure of 100 kPa-G for 29 hours. went. Table 3 shows the reaction results.

Examples 2 and 3 The amount of coke produced was evaluated in the same manner as in Example 1 except that the concentration of naphthalene in desulfurized heavy naphtha was changed to the value shown in Table 3.

Comparative Example 1 The amount of coke produced was evaluated in the same manner as in Example 1 except that nothing was added to desulfurized heavy naphtha. (Comparative Example 2) The amount of coke produced was evaluated in the same manner as in Example 1 except that the concentration of naphthalene in desulfurized heavy naphtha was changed to the value shown in Table 3.

[0033]

[Table 3]

As can be seen from Examples 1, 2, and 3 and Comparative Examples 1 and 2, the content of naphthalene in naphtha was 0.05
By setting the content by weight or more, the amount of coke generated on the metal was significantly reduced.

[0035]

As described above, according to the present invention,
In the contact reforming, by adding naphthalene to the charged raw material or by recycling a product substantially containing naphthalene, it is possible to suppress coke growing on the wall surface or inside of the contact reforming apparatus. As a result, the stability of the continuous regeneration contact reforming operation is improved, and operation under more severe conditions becomes possible, which is more advantageous in terms of production of an aromatic compound, improvement in octane number, and the like. Therefore, the industrial value of the present invention is extremely high.

Claims (2)

[Claims] 1. A method for catalytically reforming a hydrocarbon in the presence of a catalytic reforming catalyst in a catalytic reforming apparatus, the method comprising the steps of: 0.05% by weight
A method for catalytic reforming of hydrocarbons, characterized in that it contains 10 to 10% by weight of naphthalene. 2. In a contact reforming apparatus, when a hydrocarbon is subjected to catalytic reforming in the presence of a catalyst for catalytic reforming, a feedstock containing the hydrocarbon and hydrogen is contained in the raw material containing the hydrocarbon and hydrogen. 0.05% by weight
A method of suppressing coking, comprising suppressing coke generated inside the contact reforming device by containing 10% by weight of naphthalene.