RU2019290C1 - Microspherical zeolite-containing catalyst for conversion of aliphatic hydrocarbons c1- c4 - Google Patents

Abstract

FIELD: chemical technology. SUBSTANCE: catalyst has, wt.-%: high-siliceous zeolite of pentasil type in hydrogen form at ratio Si/Al = 12-30 25-35; binder - zirconium oxide (ZrO₂) 5-10; promoter - zinc oxide (ZnO) 1-2; zirconium phosphate (Zr₃(PO₄)₄) 25-30, and aluminium oxide (Al₂O₃) - the rest. Content of zirconium compounds in catalyst does not exceed 35 wt. -% . Condensate and aqueous "tablet" of aluminium hydroxide are loaded in apparatus with a mixer and heating, stirred and aqueous solutions of zirconyl nitrate and zinc nitrate are added, stirred for 1 h, and zeolite ЦВМ-III in ammonium form is added. After stirring aqueous solution of ortho-phosphoric acid is added gradually, and temperature is increased up to 90-60 C, and suspension is kept for 3 h following by spraying drying at 190-220 C. Granules are roasted in the muffle furnace at 550 C for 5 h. EFFECT: enhanced properties of catalyst prepared. 4 tbl

Description

The invention relates to compositions of a microspherical zeolite-containing catalyst for converting C ₂ -C ₁₀ aliphatic hydrocarbons contained in low-octane gas condensate or straight-run gasolines and broad light hydrocarbon fractions into a high-octane gasoline component or aromatic hydrocarbon concentrate.

In aromatization reactions of C ₂ -C ₄ olefins and C ₂ -C ₁₀ paraffins, zeolites of the pentasil group — ZSM-5, ZSM-11, CVM, CVN, and others, are highly active. Zeolite is usually used in hydrogen form (Na ₂ O content less than 0.1 wt.%) [1, 2] and γ - Al ₂ O ₃ alumina as a binder. The zeolite content in the catalyst varies widely - from 1 to 99 wt.%. In addition, the catalyst may contain promoters that increase the yield of arenes - one or more metals of groups II, III or VIII of the Periodic system - usually Zn, Cd, Ga, Pt or Pd in an amount of 0.1-10 wt.%, Preferably 0, 1-2%.

Known [3] a catalyst for the dehydrocyclodimerization of aliphatic hydrocarbons With ₂ -C ₅ including 40-60 wt. % phosphorus-containing alumina (P / Al = 0.01-1). 0.1-5 wt. % gallium and crystalline aluminosilicate with SiO ₂ / Al ₂ O ₃ ≥ 1 2 (zeolite ZSM - 5). The catalyst is prepared as follows. A mixture of a gel-forming agent, hexamethylenetetramine and a source of P (usually phosphoric acid or its salts), is introduced into a mixture of freshly prepared hydrosol Al ₂ O ₃ and zeolite and a homogeneous mass is obtained which is dispersed in oil. The catalyst particles are designed in the conditions of formation of a hydrogel is washed with water, dried and calcined at 482.2 ° ^C. Compounds Ga deposited on the catalyst is impregnated or mixed with the zeolite hydrosol and Al ₂ O _3. The introduction of a phosphorus-containing alumina into the dehydrocyclodimerization catalyst provides its increased resistance to coke formation.

The introduction of zirconium salts into a bifunctional catalyst is known. The n-paraffin isomerization catalyst according to the patent [4] contains 49.9-97 wt.% Zeolite (mordenite or faujasite), 49.9 - 1 wt.% Metal oxide (Al ₂ O ₃ , binder), 0.1-1 % of the mass. Pt or Pd and 0.1-1 wt.% Zn (but not less than a noble metal). The zeolite is impregnated with a solution of Zn salt until it is mixed with a binder, and Pt (Pd) compounds are impregnated on a calcined catalyst. The use of a bimetallic pair of Zn and Pt or Zn and Pd increases the activity and selectivity of the n-paraffin isomerization catalyst.

It is known that Zr salts have weak acidic properties and can be used as catalysts. A catalyst has been patented for the conversion of methanol or dimethyl ether to C ₂ -C ₆ olefins [5], containing 1-60 wt.% (Preferably 5-20%) of partially hydrated zirconium sulfate Zr (SO ₄ ) ₂ on γ -Al ₂ O ₃ , SiO ₂ or ZrO ₂ .

The patent [6] proposes the composition of the bifunctional catalyst closest to the proposed invention. The catalyst contains 1-20 wt. % (preferably 1-5%) ZrO ₂ , zeolite with an average pore size (ZSM - 5, ZSM - 23, β) and a binder (Al ₂ O ₃ , SiO ₂ or aluminosilicate) in any proportion, as well as a noble metal). The introduction of components containing a complex zirconium cation (Zr hydroxychloride or Al ₃ Zr (OH) ₉ Cl ₄ ) into the catalyst improves the hydrothermal stability of the catalyst and the fineness of the noble metal. The compound containing the complex Zr cation is mixed with a zeolite or with a binder at any stage in the preparation of the catalyst. It is assumed that upon calcination of the catalyst granules, Zr complexes are converted to ZrO ₂ . An example of the preparation of a catalyst of the following composition (wt.%) Is given: ZSM zeolite - 5-65, Al ₂ O ₃ - 32.5; ZrO ₂ - 2.5; Pd 0.39. The zeolite is mixed with Pd (NH ₃ ) ₄ Cl ₂ dissolved in water containing the reaction products of equimolar amounts of glycine and Al ₃ Zr (OH) ₉ Cl ₄ , Al ₂ O _{3 is} added and the mass is extruded. The bulk density of the calcined catalyst is 0.63 g / cm ³ , the density is 2.65 g / cm ³ .

The microspherical catalyst used in the fluid process should have a bulk density of 0.80-0.85 g / cm ³ , avoiding uncontrolled entrainment of the catalyst with reaction products at linear practical feed rates of 0.15-0, 25 m / s In addition, the catalyst must have high abrasion resistance. These qualities are provided by the composition of the catalyst and the technology of its preparation. In this case, the catalyst should contain the maximum amount of the active component - zeolite, components with a high specific gravity and a sufficient amount of plastic component.

An increase in the content of ZrO ₂ in the catalyst to 20 wt.% Allowed in [6] is insufficient to obtain a catalyst with the necessary bulk density, and leads to a decrease in the specific surface area of the catalyst and the specific pore volume.

In accordance with the invention, the microspherical catalyst for converting C ₂ -C ₁₀ aliphatic hydrocarbons into a high-octane gasoline component enriched in aromatic hydrocarbons contains a pentasil group zeolite with Si / Al = 12-30 in hydrogen form, alumina and zirconia as a binder, zinc oxide as a promoter and zirconium phosphate in the following ratio of components, wt.%: Zeolite 25-35 ZrO ₂ 5-10 Zr (PO ₄ ) ₄ 25-30 ZnO 1-2 Al ₂ O ₃ The rest
The content of zirconium compounds in the catalyst does not exceed 35 wt.%.

The proposed composition of the catalyst differs from the known introduction of a new component - zirconium phosphate in an amount of 25-30 wt.%, Formed at the stage of calcination of the catalyst from zirconyl nitrate ZrO (NO ₃ ) ˙ 2H ₂ O and phosphoric acid H ₃ PO ₄ . Thus, the claimed solution meets the criterion of "novelty."

Known zeolite-containing catalysts include phosphorus-containing alumina [3] or zirconia [6]. However, their use in these cases in combination with other components does not provide the composition with the properties that they exhibit when used together in the claimed solution, namely, an increase in the activity of the catalyst having a bulk density of 0.80-0.85 g / cm required for practical purposes ³ .

The observed technical result is explained by the fact that under the conditions of preparation of the catalyst, phosphoric acid interacts with zirconyl nitrate to form zirconium phosphates of the conditional composition Zr ₃ (PO ₄ ) ₄ , which have catalytic activity in acid-base reactions and are involved in the conversion of aliphatic hydrocarbons C ₂ - C ₁₀ . Therefore, with close physical characteristics, a zeolite catalyst containing zirconium oxide and zirconium phosphate is more active than a catalyst containing only zirconium oxide. This is manifested in a higher degree of conversion of raw materials and a high yield of aromatic hydrocarbons and can be used to lower the process temperature or to reduce the zeolite content in the catalyst. Thus, the catalyst of the proposed composition has new properties and meets the criterion of "inventive step".

The catalyst is prepared as follows. In a steel apparatus with a stirrer and heating, an aqueous suspension of the catalyst mass of a given composition is obtained. To do this, the calculated amount of condensate and a water cake of aluminum hydroxide is loaded into the apparatus and, after mixing, an aqueous solution of zirconyl nitrate ZrO (NO ₃ ) ₂ ˙ 2H ₂ O and an aqueous solution of zinc nitrate Zn (NO ₃ ) ₂ ˙ 6H ₂ O. The resulting suspension is mixed within 1 hour. Then, the calculated amount of CVM-III zeolite in ammonium form is added to the mixer (relative crystallinity, x-ray, 100%. Si / Al = 15.7. - static capacity for water vapor 0.08 cm ³ / g, for heptane vapors 0 24 cm ³ / g). After 30 minutes of stirring the resulting suspension, a calculated amount of an aqueous solution of orthophosphoric acid H ₃ PO _{4 is} gradually added to it. The temperature in the apparatus was raised to 50-60 ^{° C} and the suspension is kept at this temperature and constant stirring for 3 hours. The suspension was drained and sent to the laboratory spray dryer on RLS-10 at a rotational speed of the spray abalone 7500-8500 rev / min at 190-220 ° ^C. The resulting microspheres calcined pellets in a muffle furnace at 550 ^{° C} for 5 h. The calcined pellets to scatter the sieves and separating the fraction 20-150 microns with a fraction of 20-50 mm for 70 wt.%.

The following are examples of the preparation of the catalysts of the proposed invention and for comparison, the results of their tests in the reactions of conversion of hydrocarbon raw materials C ₂ -C ₁₀ containing aliphatic hydrocarbons - low-octane gas condensate gasoline and light hydrocarbon fractions into a high-octane gasoline component.

EXAMPLE 1. To prepare a homogeneous aqueous suspension of the catalyst mass of a given composition, 20 l of condensate and 1400 g of an aqueous pellet of aluminum hydroxide (SPP = 80 wt.%) Are loaded into the mixer and a homogeneous suspension is obtained. Then a solution of 523.7 g of zirconyl nitrate ZrO (NO ₃ ) ₂ x x2H ₂ O in 2 l of condensate is loaded into the apparatus and a solution of 74.2 g of zinc nitrate Zn (NO ₃ ) ₂ ˙ 6H ₂ O in 1 l of condensate. After stirring for 1 h, 412 g of zeolite NH ₄ CVM-III (PPP - 15 wt%) are added to the mixer and after 30 minutes of stirring, a solution of 150.1 g of H ₃ PO ₄ in 5 l of condensate is added. The resulting mixture was stirred until homogeneous for 3 hours at 50-60 ^{° C,} drained and directed to spray.

The obtained microspherical granules were calcined in a muffle furnace at 550 ^about C for 5 hours. The catalyst has the following composition, wt.%: Zeolite CVM-III 35 ZrO ₂ 10 Zr (PO ₄ ) ₂ 25 ZnO 2 Al ₂ O ₃ 28
The catalysts of Examples 2-6 were prepared analogously to the catalyst of Example 1. The amounts of the blend components and composition calcined at 550 ^{° C} the catalysts are shown in Table. 1. The composition of the catalyst mass does not take into account water condensate, the flow rate of which for the preparation of the catalysts according to examples 1-6 is as follows: obtaining an aqueous suspension of aluminum hydroxide - 20 l; obtaining solutions of zirconyl nitrate - 2 l, zinc nitrate - 1 l, phosphoric acid - 5 l.

The specific gravity of the catalysts prepared according to examples 1-6 0.80-0.85 g / cm ³ .

 Samples of microspherical catalysts were tested in a pilot plant.

The raw material passes through a heating furnace and heated to 250 ^{° C} is supplied under distribution grid of the reactor, where the conversion of raw materials into a product enriched arenas. The process is carried out in a turbulent fluidized bed partially spent catalyst at a pressure of 0.3-0.4 MPa, temperature 360-530 ^{° C,} the volumetric hourly space velocity of 500 h ^-1 and catalyst circulation multiplicity 3-6 wt. hours for 1 hour of raw materials. The set temperature is maintained by adjusting the catalyst circulation ratio automatically.

 The reactor is equipped with independent electric heating zones. Temperature control over the height of the reactor is carried out using chromel-alumel thermocouples, the readings of which are recorded with a multi-point potentiometer KSP-4.

1 l of catalyst is charged into the reactor. Before starting the test the catalyst is heated in nitrogen flow to 250-560 ^{° C} depending on the kind of raw material. In the case of the conversion of olefin-containing gas, the generated heat is partially removed by a water cooler.

 The turbulence of the fluidized bed of the catalyst is achieved by maintaining a linear vapor velocity of the feed 0.15-0.25 m / s (calculated on the cross section of the reactor).

 The reaction products rise to the top of the reactor, are separated from the catalyst particles in the cyclone and in the filter and enter the separator, where they are separated into the liquid phase - unstable condensate and gas. The condensate after stabilization and gaseous products are analyzed.

To maintain constant activity of the catalyst, part of it through the pipeline is discharged into the regenerator. Regeneration is carried out by air (volumetric feed rate of 600 h ^-1 ) at 600 ^about C.

 The residence time of the catalyst in the reactor is 1 hour, the regeneration time is 0.25 hours.

As raw materials, gas condensate gasoline (fraction 49-142 ^о С, density 0.702 g / cm ³ ) with an octane number according to the motor method of 59.8 and a wide fraction of light hydrocarbons (NGL) of the Nizhnevartovsk condensate, as well as olefin-containing gas, similar in composition, were used. catalytic cracking fatty gas. The composition of the raw materials is given in table. 2.

Given in the table. 3, the test results of the catalysts indicate that samples containing 25-30 wt.% Zr ₃ (PO ₄ ) ₄ are more active in converting the hydrocarbon feed to a high-octane gasoline component. During the conversion of olefin-containing gas, the conversion of olefins and the yield of a liquid product increase. A similar comparison of the activity is attained at the catalyst when the temperature rises to 15 ^{° C} and the catalyst of Example 4 comprising 10 wt.% Of the zeolite is less than the comparison catalyst. When converting a wide fraction of light hydrocarbons, the catalysts prepared in accordance with the proposed invention have a higher yield of liquid products and a higher content of aromatic hydrocarbons in them. Liquid products obtained from gas condensate gasoline on the catalysts of examples 1-5 are enriched in aromatic hydrocarbons and have a higher knock resistance.

 In the table. 4 shows some characteristics of liquid products obtained by converting various types of raw materials on the catalyst prepared according to example 3, in accordance with the alleged invention.

Claims (1)

MICROSPHERIC ZEOLITE-CONTAINING CATALYST FOR THE TRANSFORMATION OF C ₂ -C ₁₀ ALIPHATIC HYDROCARBONS into a high-octane gasoline component, including high-silica zeolite of the pentasil type in the hydrogen form, with a Si / Al ratio of 12.5 oxide oxide aluminum oxide that it additionally contains zirconium phosphate in the following components, wt.%:
High Silica Zeolite 25 - 35
Zirconia 5-10
Zirconium Phosphate 25 - 30
Zinc oxide 1 - 2
Alumina Else
while the content of zirconium compounds in the catalyst does not exceed 35 wt.%.

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