KR100409083B1 - Steam cracking catalyst of hydrocarbons for olefins production - Google Patents

Abstract

The present invention relates to a steam cracking catalyst for hydrocarbon for olefin production, and more particularly, an olefin comprising an alpha alumina carrier having a surface area of 0.01 to 0.1 m 2 / g, an average pore diameter of 10 to 150 μm, and a porosity of 10 to 30%. The present invention relates to a steam cracking catalyst for producing hydrocarbons.

In addition, the present invention is 5 to 15% by weight of potassium vanadate, and boron oxide 1 to 6 with respect to an alpha alumina carrier having a surface area of 0.01 to 0.1 m 2 / g, an average pore diameter of 10 to 150 µm, and a porosity of 10 to 30%. The present invention relates to a steam cracking catalyst for hydrocarbons for producing olefins containing a catalyst supported by weight%.

The catalyst according to the present invention has a large effect of improving the yield of ethylene and propylene when applied to the steam cracking reaction of paraffinic hydrocarbons, and has excellent coke removal performance, and can greatly reduce the amount of COx generated as a byproduct during coke removal.

Description

Steam cracking catalyst of hydrocarbon for olefin production {STEAM CRACKING CATALYST OF HYDROCARBONS FOR OLEFINS PRODUCTION}

The present invention relates to a steam cracking catalyst for olefin production hydrocarbons, and more particularly, to a catalyst for ethylene and propylene production which can reduce the amount of coke and COx generated while simultaneously improving the yield of ethylene and propylene by steam cracking hydrocarbons.

Ethylene and propylene are important basic raw materials for petrochemicals. The ethylene and propylene are mainly produced by pyrolyzing hydrocarbons containing paraffinic compounds as main components such as natural gas, naphtha and gas oil at high temperature of 800 ° C. or higher in the presence of steam. In order to increase the yield of ethylene and propylene in steam cracking of hydrocarbons, the conversion of hydrocarbons or the selectivity of olefins should be increased. However, since pure steam pyrolysis has reached the limit for increasing the conversion of hydrocarbons and the selectivity of olefins, various methods for increasing the yield of olefins have been proposed.

A steam cracking method using a catalyst has been proposed as a method for improving the yield of ethylene and propylene in steam pyrolysis of hydrocarbons. U.S. Patent No. 3,644,557 uses a catalyst composed of magnesium oxide and zirconium oxide, U.S. Patent No. 3,969,542 uses a catalyst based on calcium aluminate, while U.S. Patent No. 4,111,793 uses a manganese oxide catalyst supported on zirconium oxide. Patent 0212320 A2 proposes an iron catalyst supported on magnesium oxide, and US Pat. No. 5,600,051 proposes a catalyst composed of barium oxide, alumina and silica. However, the catalysts of the above methods have the advantage of significantly increasing the olefin yield in the steam cracking reaction of hydrocarbons, but there is a problem in that the coking of the catalyst is severe.

Hydrocarbon decomposition reactions at high temperatures give rise to coke. Although steam is used as the reactant diluent to remove such coke, coking still occurs severely and accumulates in the reactor walls, causing various problems as follows.

That is, the coke accumulated on the pyrolysis reaction tube wall increases the heat transfer resistance, thereby reducing the amount of heat transfer to the hydrocarbon. As the heat transfer resistance increases, the reactor must be heated more to supply sufficient heat for the reaction, which leads to an increase in the reactor surface temperature, which shortens the reactor life. Also, coke accumulated on the reactor wall reduces the effective cross-sectional area of the reactor, increasing the differential pressure of the reactor and consequently requiring more energy to compress and inject the reactants.

As described above, in the steam cracking reaction of hydrocarbons, the heat transfer resistance or the differential pressure increases due to the coke, making it impossible to operate the reactor normally. For the normal operation of the reactor, the reactor operation must be stopped and the coke removed. In particular, when the catalyst is used in the hydrocarbon steam cracking reaction, coke accumulates not only on the reactor wall but also on the surface of the catalyst, so that problems due to coking may be more serious. Accumulation of coke on the surface of the catalyst not only degrades the performance of the catalyst, but also increases the differential pressure on the catalyst layer due to the accumulated coke, so that the reactor operation may need to be stopped more frequently for normal reactor operation. The catalyst surface acts to capture and condense coke precursors produced in the gas phase and, depending on the catalyst component, has the activity of promoting coke formation, so that the catalyst for steam cracking reaction of hydrocarbons can prevent coking as much as possible. Should have

Commercial steam pyrolysis reactors usually remove coke in cycles of 30 to 60 days. To do this, the coke is removed by shutting down the reactor and blowing air under a steam atmosphere. The time it takes to remove coke depends on the amount of coke accumulated in the reactor, which usually takes 1 to 2 days. However, if the coke removal cycle is significantly shortened by using a catalyst with insufficient coke removal performance, even if the catalyst is used to increase the yield of ethylene and propylene, the yield of ethylene and propylene per unit period may be reduced compared to pure pyrolysis process. In addition, the additional cost for coke removal can increase significantly. Therefore, in order to have an economical process using a catalyst in steam cracking of hydrocarbons, a catalyst capable of minimizing the coking of the catalyst and extending the coke removal cycle is required.

As a method for reducing coke formation in a catalyst, a method of gasifying and removing coke has been proposed. U.S. Patent No. 3,872,179 proposes a catalyst for adding an alkali metal oxide to a zirconia catalyst, and Russian Patent No. 1,011,236 proposes a potassium vanadate catalyst modified with boron oxide on an alumina carrier. Alkali metal oxides or potassium vanadate compounds presented in the above invention are very effective in removing coke because they have the ability to gasify the generated coke with COx, and also increase the amount of loading to improve the coke removal performance and the coke removal cycle. The advantage is that it can be extended. However, the COx generated during the gasification of the coke must be removed because it causes contamination and plugging in the downstream process of separating the olefins. However, as the COx generation concentration increases, the separation cost increases significantly.

In view of the problems in the prior art, an object of the present invention is to provide a steam cracking catalyst for olefin production hydrocarbons that can minimize the amount of COx while having excellent coke removal performance as a catalyst for ethylene and propylene production.

The present invention to achieve the above object,

In the hydrocarbon steam cracking catalyst for olefin production,

A hydrocarbon steam cracking catalyst for olefin production comprising an alpha alumina carrier having a surface area of 0.01 to 0.1 m 2 / g, an average pore diameter of 10 to 150 μm, and a porosity of 10 to 30% is provided.

In addition, the present invention is a hydrocarbon steam cracking catalyst for olefin production,

For preparing an olefin carrying 5 to 15% by weight of potassium vanadate and 1 to 6% by weight of boron oxide to an alpha alumina carrier having a surface area of 0.01 to 0.1 m 2 / g, an average pore diameter of 10 to 150 μm, and a porosity of 10 to 30%. A hydrocarbon steam cracking catalyst is provided.

Hereinafter, the present invention will be described in detail.

Conventional hydrocarbon steam cracking reaction is a reaction for producing ethylene and propylene by steam pyrolysis of a reactant at a high temperature of 800 ° C. or higher under a catalyst-free condition using natural gas, naphtha, gas oil and the like as a reactant.

The present invention uses an alpha alumina carrier having a very small surface area as a decomposition catalyst for steam pyrolysis of such hydrocarbons.

The present invention also includes a catalyst in which potassium vanadate and boron oxide are supported as an active ingredient using alpha alumina having a small surface area as a carrier for steam decomposition catalyst of hydrocarbons.

It is preferable that the physical property of the said alpha alumina is 0.01-0.1 m <2> / g in surface area, 10-150 micrometers of average pore diameters, and 10-30% of porosity. The alpha alumina has a chemical composition comprising an oxide of at least one component selected from the group consisting of silica, alkali metals and alkaline earth metals. Preferably, the alkali metal and alkaline earth metal may be selected from at least one selected from the group consisting of sodium, potassium, magnesium, calcium, and barium. More preferably, the alpha alumina is 85 to 90% by weight of aluminum oxide, 9.0 to 12.0% by weight of silicon oxide (silica), 0.2 to 0.4% by weight of sodium oxide, 0.3% by weight or less of iron oxide, 0.2 to 0.4% by weight of titanium oxide, calcium 0.1 to 0.6 wt% of oxide, 0.1 to 0.4 wt% of magnesium oxide, 0.1 to 0.2 wt% of potassium oxide, and 0.8 wt% or less of barium oxide.

In the present invention, potassium vanadate and boron oxide are used as active ingredients included in the alpha alumina carrier. The amount of the active ingredient supported is preferably 5 to 15% by weight of potassium vanadate and 1 to 6% by weight of boron oxide based on the weight of the alpha alumina carrier. At this time, the precursors of potassium vanadate and boron oxide are used potassium hydroxide, ammonium vanadate, and boric acid, these precursors can be obtained by supporting the conventional initial impregnation method or liquid impregnation method. Therefore, the catalyst is prepared by dissolving the precursor of the active ingredient in water to form an aqueous solution, and then impregnating the aqueous solution with an alpha alumina carrier by an initial impregnation method or a liquid impregnation method, drying at 120 ° C. for at least 10 hours, and then 750 ° C. The catalyst may be prepared by baking for 4 hours or longer at

The potassium vanadate used as an active ingredient in the present invention has an activity of converting coke to COx, which is effective for removing coke, and boron oxide also serves to inhibit coke accumulation while increasing the dispersion of potassium vanadate. do.

Accordingly, the catalyst in which potassium vanadate and boron oxide are supported on an alpha alumina carrier having a small surface area of the present invention can significantly reduce the amount of COx generated as a by-product, compared to the catalyst in which potassium vanadate and boron oxide are supported. High performance can be maintained. In addition, the use of alpha alumina having a small surface area as a carrier in the present invention does not reduce the yield of ethylene and propylene, but rather has an effect of improving the yield of ethylene and propylene over a catalyst having a large surface area.

In the case of the conventional catalyst, when the coke removal performance is excellent, there is a problem that the coke removal performance is lowered when the amount of COx is excessively generated or vice versa. In contrast, the present invention is very advantageous in reducing the amount of coke accumulated in the catalyst by using alpha alumina having a very small surface area and porosity as the catalyst itself or the carrier. That is, the coke accumulated in the catalyst is converted to COx and removed, and the amount of COx generated because the accumulated amount of coke is small can be reduced. However, the alpha alumina used in the hydrocarbon steam cracking catalyst of the present invention preferably has a minimum surface area and porosity capable of supporting the amount of the coke removing component potassium vanadate and boron oxide as necessary.

Conventionally, the surface area of the catalyst or carrier for steam decomposition of hydrocarbons is proposed to be 1 m 2 / g or less. According to the present invention, even if the surface area of alpha alumina is 1 m 2 / g or less, the coke accumulates in the catalyst when the surface area is 0.1 m 2 / g or more. The amount is high and the amount of COx is generated.

In applying the catalyst to the hydrocarbon steam cracking reaction in the present invention, applicable reactor types include fixed bed reactors, fluidized bed reactors, and mobile bed reactors.

In particular, the present invention may use the alpha alumina carrier as a catalyst in a reaction process in which the catalyst is repeatedly regenerated in a short cycle such as a fluidized bed reactor or a mobile bed reactor. According to the present invention, when alpha alumina having the above-described characteristics is used for hydrocarbon steam cracking reaction in a fluidized bed or mobile bed reactor, alpha alumina acts as a heat transfer medium to increase the conversion of hydrocarbon and thus increase the yield of ethylene and propylene. In addition, the alpha alumina proposed in the present invention has the advantage that it is easier to remove the coke and reduce the cost of removing the coke compared to the conventionally proposed catalyst (or solid heat medium) having a large porosity and porosity.

In addition, when the steam decomposition reaction of hydrocarbons is carried out in a fixed bed reactor, it is preferable to use a catalyst in which potassium vanadate and boron oxide are supported on an alpha alumina carrier. The catalyst used in the fixed bed may be formed into a spherical or pellet form, but in this case, there is a problem in that the differential pressure is largely applied to the catalyst layer. In order to solve this problem, in order to solve this problem, the catalyst layer may have a LASIK ring or other special form. It is good to mold the catalyst.

In addition, as a catalyst for selectively decomposing hydrocarbon steam, heat-resistant oxides such as zirconium oxide, magnesium oxide, magnesium aluminate, etc. having a surface area and porosity similar to those of the alpha alumina may be used as a carrier, in addition to the alpha alumina supported catalyst provided in the present invention. have.

In the present invention, the reaction for preparing an olefin using a hydrocarbon steam cracking catalyst is carried out under conventional steam pyrolysis reaction conditions. For example, in the presence of the hydrocarbon steam cracking catalyst, steam pyrolysis is carried out under the conditions of a reaction temperature of 600 to 1000 ° C., a ratio of steam / naphtha 0.3 to 1.0, and LHSV 1 to 20 ^{hr −1} to produce an olefin.

As described above, the present invention is capable of obtaining a high yield of ethylene and propylene by applying the catalyst to steam pyrolysis of hydrocarbons, and in particular, the amount of COx generated as a by-product when removing coke and coke generated during the reaction is conventionally used. It can be significantly reduced than the catalyst.

Hereinafter, the effect of the present invention through the examples. However, this invention is not limited only to a following example.

[Comparative Examples 1-3 and Examples 1-4]

As a catalyst, alpha alumina carriers A to G having physical properties as shown in Table 1 provided by Norton were used. Alpha alumina is spherical with a 5 mm diameter, the physical properties and chemical composition thereof are shown in Table 1. Porosity shown in Table 1 represents the porosity measured by moisture absorption.

division Comparative Example 1 Comparative Example 2 Comparative Example 3 Example 1 Example 2 Example 3 Example 4 carrier A B C D E (Bimodal Pore) F G Physical properties Surface area (㎡ / g) 0.88 0.76 0.32 0.01 0.07 0.04 0.05 Porosity (%) 29.2 53.6 34.1 27.14 16.4 21.89 28.12 Average pore diameter (㎛) 1.3 6.1 4 146.8 15/150 19.76 20 Chemical composition (% by weight) Aluminum oxide 99.6 85-100 90 86.1 86.2 86.2 89.4 Silicon oxide 0.1 0-15 10 12 11.5 11.5 9.3 Sodium oxide 0.3 - 0.2 0.2 0.4 0.4 0.4 Iron oxide - - - 0.1 0.3 0.2 - Titanium oxide - - - 0.2 0.4 0.4 0.3 Calcium oxide - - 0.1 0.6 0.1 0.1 0.1 Magnesium oxide - - - 0.4 0.1 0.1 0.1 Potassium oxide - - - 0.1 0.2 0.2 0.2 Barium oxide - - - - 0.8 0.8 -

Experimental Example 1

Hydrocarbon steam decomposition reaction was carried out using the alpha alumina (the above carriers A to G) carrier of Table 1 as a catalyst. In this case, naphtha was used as a hydrocarbon, and the composition and properties of the used naphtha are shown in Table 2 below.

Specific gravity, g / cc 0.675 Initial boiling point, ℃ 30.9 Apocalyptic boiling point, ℃ 160.7 n-paraffins, wt% 39.5 I-paraffins, weight percent 38.9 Naphthenic, wt% 15.3 Aromatic, wt% 6.3

The reactant naphtha and water were injected into the reactor with a metering pump. At this time, the naphtha and water injection ratio was 2: 1 by weight ratio, and the naphtha flow rate was adjusted to 10 LHSV. Naphtha and water injected into the reactor were respectively mixed through a vaporizer, passed through a primary preheater heated to 550 ° C., and then injected into a reactor filled with a catalyst through a secondary preheater heated to 650 ° C. The reactor used a quartz reactor (length: 18 cm, diameter: 1/2 inch), the temperature of the electric furnace was set to 920 ℃. The steam-naphtha mixture passed through the secondary preheater caused a catalytic pyrolysis reaction through the reactor. The reaction product was passed through two condenser connected in series, water and heavy oil condensed into the liquid phase, and the remaining gas phase mixture was analyzed by on-line gas chromatography and discharged. The yield of ethylene was calculated by Equation 1 below, and the yield of other products was calculated in the same manner.

And, Table 3 shows the results of the naphtha steam decomposition reaction. The coke amount is expressed in weight percent based on the amount of naphtha injected during the 4 hour reaction.

division Comparative Example 1 Comparative Example 2 Comparative Example 3 Example 1 Example 2 Example 3 Example 4 Alumina carrier A B C D E F G Carrier surface area (㎡ / g) 0.88 0.76 0.32 0.01 0.07 0.04 0.05 Catalyst filling amount (㎡ / g) 14.25 9.66 12.02 11.63 13.59 11.52 10.42 Methane (% by weight) 12.9 13.6 13.2 14.4 13.5 - 13.1 Ethylene (% by weight) 32.1 34.0 32.8 35.0 33.6 - 33.1 Propylene (wt%) 15.0 15.9 15.4 14.9 15.7 - 16.1 Ethylene + Propylene (wt%) 47.1 49.9 48.2 49.9 49.3 - 49.1 Cork (wt%) 1.42 1.53 1.13 0.13 0.51 0.29 0.39

In Table 3, the hydrocarbon steam decomposition reaction was performed using only the alpha alumina carrier to compare the amount of coke generated under conditions of similar olefin yield. In Examples 1 to 3, the amount of coke generated was 1 m 2 / g or less. In the case of Examples 1 to 4 using the carriers D, E, F, and G having a surface area of 0.01 to 0.1 m 2 / g having a smaller surface area than the catalyst, while generating a large amount using the carriers A, B, and C having a large surface area There were few. [Comparative Examples 4-6 and Examples 5-8]

Preparation of Catalysts (KVO ₃ -B ₂ O ₃ / α-alumina)

Carriers used in the preparation of the catalyst were prepared in Comparative Examples 4 to 6 and Examples 5 to 8 using the alpha alumina A to G of Table 1, respectively.

2.03 g of potassium hydroxide, 4.24 g of ammonium vanadate, and 3.54 g of boric acid, which are precursors of the supported component, are dissolved in about 15 to 50 g of water according to the porosity of alpha alumina to form an aqueous solution. It was supported by the initial impregnation method. The catalyst impregnated with an aqueous solution of the catalyst precursor in alpha alumina was dried in an air atmosphere at 120 ° C. for at least 10 hours, and then transferred to a sintering furnace to raise the temperature to 750 ° C. at a rate of about 12 ° C./min at room temperature, and for 4 hours at this temperature. The catalyst was calcined while maintaining, and then slowly cooled to room temperature in the kiln. The catalysts completed by firing according to the above-described procedure had a composition having a composition of 5% by weight of potassium vanadate and 2% by weight of boron oxide relative to the weight of the alpha alumina carrier, and had a spherical diameter of 5 mm.

Experimental Example 2

Steam decomposition of the hydrocarbon was carried out using the catalysts prepared in Comparative Examples 4 to 6 and Examples 5 to 8, wherein naphtha of Table 2 was used as the hydrocarbon.

The reactant naphtha and water were injected into the reactor with a metering pump. At this time, the naphtha and water injection ratio was 2: 1 by weight ratio, and the naphtha flow rate was adjusted to 10 LHSV. Naphtha and water injected into the reactor were respectively mixed through a vaporizer, passed through a primary preheater heated to 550 ° C., and then injected into a reactor filled with a catalyst through a secondary preheater heated to 650 ° C.

The reactor (material: inconel, outer diameter: 1/2 inch, catalyst bed length: 60 cm) was heated to 880 ° C. by an electric furnace composed of three stages, and the steam-naphtha mixture passed through the secondary preheater as in Experiment 1 was used to prepare the reactor. A catalytic pyrolysis reaction occurred as it passed. The reaction product was passed through two condenser connected in series, water and heavy oil condensed into the liquid phase, and the remaining gas phase mixture was analyzed by on-line gas chromatography and discharged. The yield of ethylene and other products was calculated by the above equation.

In Table 4, the results of naphtha contact steam cracking reaction and pure steam pyrolysis reaction results are shown. Yields of ethylene and propylene, and H ₂ , CO, CO ₂ , and coke amounts are expressed in weight percent based on the amount of naphtha injected during the 4 hour reaction.

division catalyst pyrolysis Comparative Example 4 Comparative Example 5 Comparative Example 6 Example 5 Example 6 Example 7 Example 8 carrier A B C D E F G - Carrier Surface Area (㎡ / g) 0.88 0.76 0.32 0.01 0.07 0.04 0.05 - Catalyst filling amount (g) 50.85 33.68 44.85 41.83 52.94 56.39 43.3 - Methane (% by weight) 12.5 12.7 12.9 13.2 13.2 13.8 13.6 9.2 Ethylene (% by weight) 32.4 32.4 32.5 34.3 32.7 34.3 34.1 23.9 Propylene (wt%) 17.0 16.7 15.9 16.4 16.2 16.0 15.9 12.8 Ethylene + Propylene (wt%) 49.5 49.1 48.4 50.7 48.9 50.3 50.0 36.7 H ₂ (% by weight) 1.48 1.53 0.91 0.98 0.95 0.97 0.96 0.64 CO (% by weight) 0.66 0.75 0.06 0.09 0.07 0.07 0.08 0.05 CO ₂ (% by weight) 2.27 2.46 0.01 0.00 0.01 0.01 0.01 0.00 Cork (%) 0.47 0.47 0.78 0.16 0.27 0.27 0.31 0.13 CO + CO ₂ (wt%) 2.92 3.20 0.07 0.09 0.08 0.07 0.09 0.05 Cork + CO + CO ₂ (% by weight) 3.39 3.67 0.85 0.24 0.35 0.35 0.41 0.18

In Table 4, in Examples 5 to 8, the amount of coke and COx was higher than that of pure pyrolysis when using a catalyst, and the yield of ethylene + propylene was significantly improved compared to pyrolysis.

On the other hand, when comparing the amount of coke and COx generated under conditions similar to olefin yield, the amount of generated by using carriers A, B, and C having a large surface area of 1 m 2 / g or less for the amount of coke and COx generated in Comparative Examples 4 to 6 On the other hand, the amount of coke and COx generated was small in Examples 5 to 8 using carriers D, E, F, and G having a surface area of 0.01 to 0.1 m 2 / g having a smaller surface area than the catalyst.

As described above, since the catalyst for steam decomposition of hydrocarbons of the present invention uses alpha alumina having a small surface area and porosity as the catalyst itself or a carrier, the amount of coke accumulated in the catalyst can be greatly reduced. By using the date and boron oxide, the yield of ethylene and propylene can be greatly improved compared to pure steam pyrolysis reaction, and at the same time, the amount of COx generated when removing coke is very small, which does not burden the separation process of gaseous products, and fixed bed. It can be applied not only to the reactor but also to a mobile bed or a fluidized bed reactor, and in particular, the alumina itself can be used as a catalyst in a mobile bed or a fluidized bed reactor having a short coke removal cycle.

Claims (5)

In a hydrocarbon steam cracking catalyst for producing olefins in which potassium vanadate and boron oxide are supported on an alumina carrier, The alumina carrier is a hydrocarbon steam cracking catalyst for olefin production, characterized in that it comprises an alpha alumina carrier having a surface area of 0.01 to 0.1 m 2 / g, an average pore diameter of 10 to 150 μm, and a porosity of 10 to 30%. The hydrocarbon steam cracking catalyst for producing olefins according to claim 1, wherein the potassium vanadate is supported by 5 to 15% by weight and 1 to 6% by weight of the boron oxide. The hydrocarbon steam cracking catalyst for producing olefins according to claim 1 or 2, wherein the alpha alumina carrier comprises at least one component selected from the group consisting of silica, alkali metals and alkaline earth metals. 4. The hydrocarbon steam cracking catalyst for producing olefins according to claim 3, wherein the silica is contained in an amount of 9 to 12% by weight. 4. The hydrocarbon steam cracking catalyst for producing olefins according to claim 3, wherein the alkali metal and the alkaline earth metal are selected from the group consisting of sodium, potassium, magnesium, calcium, and barium.