RU2384366C2 - Heterogeneous catalyst and method of producing alkylation gasoline - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention relates to a solid heterogeneous super acid catalyst for synthesis of alkylation gasoline by bringing a liquid mixture of isobutane and butenes into contact with the said catalyst which is a porous composition made from a template substrate consisting of particles of an "expanded" intercalated mixture of acids and hexahydrate of cerium (III) nitrate graphite having nano-sized pores and an inorganic acid deposited on particles of the said graphite, where the said inorganic acid is based on zirconium metallosilicates promoted with zinc or nickel sulphates or mixtures thereof, having the following general formula: (ZrO₂·17SiO₂)·0.5MSO₄, where M=Zn²⁺ and/or Ni²⁺. The invention also relates to a method of producing alkylation gasoline via alkylation of isobutane with a mixture of butenes in the presence of the above mentioned catalyst at temperature ranging from 50 to 70°C, pressure ranging from 1.7 to 3.0 MPa, molar ratio of isobutane to butenes equal to 15:1, feed space velocity of material ranging from 6.4 to 8.5 g/ml_cat·hour, and possibly subsequent regeneration of the said catalyst.

EFFECT: invention increases service life of the catalysts and increases their activity and selectivity.

7 cl, 3 ex, 1 tbl

Description

The invention relates to the chemistry of heterogeneous catalysis, in particular to processes for producing the high-octane component of gasoline, referred to in the refining industry as “alkylate”. The alkylate production process is based on the alkylation reaction of isoparaffins (isobutane) with lower olefins (propene, butenes). Industrial alkylation catalysts are anhydrous hydrogen fluoride or concentrated sulfuric acid. The technological design of the reaction has been brought to a high degree of perfection - no more than 0.4 kg of hydrogen fluoride or 70 kg of sulfuric acid is required to obtain 1 ton of alkylate. Despite the return and regeneration of the used catalysts, the cost of alkylate at 30% is determined by the price of the catalyst. Reducing the requirements for the quality of reagents (in terms of moisture, dienes, sulfur-containing compounds) increases the consumption of hydrogen fluoride to 1 kg per 1 ton of alkylate, and the consumption of sulfuric acid increases to 200 kg / t of alkylate. Toxicity, a correlating effect on equipment materials, the formation of difficult to recycle waste with a global scale of alkylate production exceeding 70 million tons per year, and a high probability of environmental disasters make the use of these catalysts very problematic.

Various acid heterogeneous systems have been proposed as alternative catalysts for the alkylation reaction. Only four of them are brought to the level of demonstration pilot plants. Among them are the developments of Haldor Topsoe, Catalitika, Neste Oy, Konoko, Chemical Research and Licensing, Chevron and UOP. The developments of these firms proposed several technological schemes for the use of heterogeneous catalysts, among them:

1. Known Bronsted acids heterogenized on inorganic carriers of a porous and non-porous nature, as described in European Patents EP 0433954 A1, EP 0542620 A1.

2. Known Lewis acids heterogenized on inorganic crystalline supports with regular porous structure (zeolites) or on polymer supports, both zeolites and organic polymers initially possess the Bronsted acid function, US Pat. Nos. 3,975,299, 4,384,161, 4,992,616.

3. Polymer materials containing perfluoroalkylene sulfonic or perfluoroarylene sulfonic groups, their use is described in US patents 3855342, 3862258, 4038213.

4. Solid inorganic crystalline materials with a regular porous structure of certain sizes (zeolites) having both the properties of Bronsted and Lewis acids, US patents 4300015, 4992615, 5258569, world patents WO 93/017106, 99/19279.

5. Solid inorganic amorphous materials with an irregular porous structure, modified by the deposition of compounds with the properties of "super acid". By a well-known definition, “superacid” is a mixture of such compounds that separately possess the properties of Bronsted and Lewis acids with known properties, and their mixture surpasses in strength 100% sulfuric acid. Patent information on the catalytic effect of such systems is represented by Japanese patents 51-63386, 57-3650, 59-40056, 59-6181, 61-242461; China 1230463, 1362286; US 3251902, 3655813, 4377721, 5491278, 5493067, which together set forth the concept of analogues of our invention, and RF patent 2313391, adopted by us for the prototype of the invention.

All five areas of using heterogeneous catalysts for the production of alkylate require professional expert evaluation on a number of parameters. These parameters of the alkylation process are:

- the conversion of olefins (butenes), K%, which at the time of completion of the inter-regeneration run of the catalyst should be at least 90%,

- the yield of alkylate on the missed butenes, In wt.%. In real conditions, alkylation includes not only the main reaction of isobutane + butenes → trimethylpentanes, dimethylhexanes (alkylate) alkylate formation (1), but also a side process of butene oligomerization → butene oligomer (2). Therefore, the theoretical yield of reaction products according to equations (1) and (2) is taken equal to 203.6 and 100 wt.%, Respectively. In the presence of superacids, the yield of alkylate increases due to the self-alkylation of isobutane 2 (isobutane) → trimethylpentanes, dimethylhexanes (alkylate) + hydrogen (3) and increases up to 210% or more,

- productivity on alkylate, measured by the mass of alkylate produced by the unit mass (volume) of the catalyst for 1 hour, Pkg _alk / kg _cat · h, kg _alk / l _cat · h,

- the resource (lifetime) of the catalyst, measured by the amount of alkylate obtained from a unit mass (volume) of catalyst for the inter-regeneration run, Rkg _alk / kg _cat , kg _alk / l _cat . The duration of the catalyst run in hours is the quotient of dividing the value of P by the value of P.

The operating parameters for the catalysts of all five of the above types of catalysts are presented in the table. As follows from the table, the best indicators for the yield of alkylate, productivity and resource of action have a prototype catalyst.

Performance characteristics of heterogeneous catalysts for the production of alkylate in accordance with the five concepts of their origin Indicators Heterogeneous catalysts in accordance with the concept 12 3, 4 5 Analogs Prototype The conversion of butenes, K% 98-100 90-100 95-100 96-100 The yield of alkylate, In wt.% 190-210 180-210 195-200 195-215 Alkylate Performance P 2.0-2.1 0.05-1.0 0.2-0.3 0.2-1.7 kg _alk / kg _cat · h (1.2-1.3) (0.03-0.6) (0.1-0.24) (0.12-0.99) Resource, Rkg _alk / kg _cat 500-600 3-24 20-50 300-670 (300-360) (2-15) (14-35) (180-400) Life time, h 250-300 40-200 80-250 200-880 Possibility of regeneration No 3 - no, 4 - yes Yes Yes Note: in brackets are indicated the volumetric indicators, kg / l · h, kg / l.

All other catalysts have no prospects for implementation either on environmental or on technical and economic indicators. The authors of the analogue of the Russian Federation 2091360 declared the presence of high rates of the proposed catalysts by the method of their synthesis, characterized in that at the first stage of preparation of the catalyst it is necessary to synthesize a carrier matrix, and then at the second stage apply the active component with a particle size of not more than 1-50 nm on the carrier. The samples of the catalysts of the prototype of the Russian Federation 2313391, made using nanotechnological techniques, exceeded the technical samples of the analogue of the RF 2091360 in technical and economic indicators. However, during the long-term operation of the catalysts of the prototype, shortcomings appeared. So, despite the high reproducibility of the prototype in the process of scaling catalyst samples, i.e. during the transition to industrial methods of preparation, there was a loss in the multiplicity (repeatability from experience to experience) of operational indicators. Regeneration in the presence of hydrogen, especially at a pressure increased to 5 MPa, was accompanied by the loss of high qualities of the catalyst, which occurred at a certain critical temperature of regeneration. The analysis of the samples that lost their activity by physicochemical methods showed that the cause of the deactivation of the samples according to the prototype is not only the enlargement of platinum or palladium particles, but also the partial reduction of metal sulfates to sulfides, which is irreversible.

The objective of the invention is the creation of an environmentally friendly method for producing gasoline-alkylate in the presence of a superacid heterogeneous catalyst with high reproducibility of performance in the conditions of preparation of catalytic factories using existing equipment.

To solve the technical problem, we propose a method for producing the named catalyst, characterized in that the precursor substances of the active active components of the catalyst are applied to the template substrate from a carbon-containing material consisting of particles having nanosized pores (the materials are described by Ubellode A. R., Lewis F.A. Graphite and its crystalline compounds, Moscow: Mir, 1965. P.126. Kinetics and Catalysis, 2007, Volume 48, No. 4, pp. 612-620, Advances in Chemistry ", 2006, Volume 75, No. 11, pp. 1119-113 2).

The alkylation catalyst is prepared as follows.

First prepare the template substrate. For this purpose, natural graphite de-acidified by processing acid in the form of particles passing through a sieve with a mesh size of 0.3 mm and remaining on a sieve of 0.1 mm, having a bulk density of about 800 kg / m ³ , in an amount of 100 g is wetted with a mixture of 100 g of 96-98% sulfuric acid and 50 g of 68% nitric or 72% perchloric acid at room temperature. The mixture also contains in the indicated quantity (150 g) 20 g of cerium (III) nitrate hexahydrate. After ten minutes of exposure, the mass of graphite impregnated with the acid mixture is washed until the washing liquid reaches pH 0. The graphite thus intercalated is dried at 120 ° C to constant weight and heated in a muffle furnace at a temperature of 900 ° C for 60 s. Get about 8 l of "expanded graphite" with a bulk density of 10 kg / m ³ , which indicates the high porosity of the obtained material. In addition, an analysis of “expanded graphite” particles shows that they have nanoscale pores. Apparently, these pores form (as templates) nanosized particles of the superacid component promoted by nickel or zinc sulfates (or mixtures thereof) of zirconium silicate.

Example 1. 100 g of "expanded graphite" is placed in 10 l of a solution prepared as follows:

210.0 g of tetramethoxy- or 280.0 g of tetraethoxysilane are hydrolyzed in 600 ml of distilled water containing 50 mmol of nitric or hydrofluoric acid. The temperature during hydrolysis is not higher than 30 ° C. To a clear hydrolyzed solution, with stirring, a solution of 21.1 g of zirconyl nitrate dihydrate and 11.8 g of zinc sulfate heptahydrate or 10.4 g of nickel sulfate hexahydrate in 200 ml of water is added, stirred and diluted to a volume of 10 l with distilled water. A suspension of "expanded graphite" in the prepared solution is sprayed in the flame of an air-propane burner. The finely dispersed powder is collected in a cyclone using a filter heated to a temperature of 120 ° C, dried at a temperature of 150-200 ° C and impregnated with a solution of tetramminplatinum or tetramminpaladium dichlorides containing 2.0 g of platinum or 1.0 g of palladium. Wet powders are dried to constant weight and tableted by dry pressing. The optimum bulk density of the tablets is 500 kg / m ³ . The tablets are activated by heating in an oven at a maximum temperature of 600 ° C for 1 hour. The finished catalyst is placed in a hermetically sealed container. The cooled tablets are transferred to a tubular reactor, sealed and flushed with an inert gas when the temperature rises to 50-70 ° C, under a pressure of 3 MPa for 1 hour. Then a liquid mixture of isobutane with butenes with a molar ratio of components of 15: 1 is fed into the reactor, while the feed mixture is 6.4-8.5 g / ml _cat · h.

When feeding such a raw material mixture in an amount of 8.5 g / ml _cat · h, the following process indicators are achieved. At a temperature of 50 ° C and a pressure of 3.0 MPa, the indicators K, B, P and P are equal, respectively, 97-99.190-210, 0.975-1.077 and 180 in the units indicated in the table.

Example 2. At a temperature of 70 ° C, a pressure of 3.0 MPa and a feed rate of the raw mix of 6.4 g / ml _cat · h, the indicators were 98-100%, 185-205, 0.702-0.777, 154-170.220, respectively.

Example 3

The catalyst according to claim 1, deactivated under the conditions of example 1 at a temperature of 70 ° C, is washed at a temperature of 100 ° C and a pressure of 2.5 MPa with a mixture of equal volumes of isobutane and carbon tetrachloride, supplied at a flow rate of 1 hour ^-1 for 5 hour. The end of the regeneration corresponds to the absence of gasoline-alkylate components in the washing liquid at the level of 0.1 wt.%, Recorded by GLC. The temperature is reduced to 60 ° C and, under a pressure of 2.5 MPa, a raw material mixture of the above composition is fed into the reactor with a feed rate of 6.4 g / ml _cat · h, obtaining the following indices K, B, P, P, whose dimension and lifetime catalyst are presented in the table: 97-99,185-208, 0,690-0,776, 150-170,220.

Claims (7)

1. Solid heterogeneous superacid catalyst for producing gasoline alkylate by contacting a liquid mixture of isobutane and butenes with this catalyst, which is a porous composition from a template substrate, consisting of particles of "expanded" graphite containing cerium (III) nitrate, intercalated with a mixture of acids and hexahydrate, having nanosized pores, and an inorganic acid supported on particles of such graphite based on zirconium metallosilicates promoted with zinc or nickel sulfates or mixtures thereof, having a total formula
(ZrO ₂ · 17SiO ₂ ) · 0.5MSO ₄ ,
where M is Zn ²⁺ and / or Ni ²⁺ . 2. The catalyst according to claim 1, characterized in that it is obtained in two stages: at the first stage, a substrate template is formed from “expanded” intercalated graphite; in the second stage, inorganic acid based on zirconium metallosilicates promoted with zinc or nickel sulfates or mixtures thereof is applied to the particles of said graphite. 3. The catalyst according to claim 1, characterized in that the mass fraction of particles of "expanded" graphite is at least 50%. 4. The catalyst according to claim 1, characterized in that it further comprises 1.0 wt.% Platinum or 0.5 wt.% Palladium. 5. The catalyst according to claim 4, characterized in that platinum or palladium in the catalyst base is introduced in the form of tetrammine chloride of their metals. 6. The method of producing gasoline-alkylate by alkylation of isobutane with a mixture of butenes in the presence of a catalyst according to one of claims 1 to 4 at a temperature of from 50 to 70 ° C, a pressure of from 1.7 to 3.0 MPa, a molar ratio of isobutane: butenes 15: 1, the volumetric feed rate from 6.4 to 8.5 g / (ml _cat · h) and the subsequent possible regeneration of the specified catalyst. 7. The method according to claim 6, characterized in that the regeneration of the catalyst is carried out by washing it with a mixture of equal volumes of isobutane and carbon tetrachloride at a volumetric feed rate of the mixture 1 h ^-1 at a temperature of 80-100 ° C and a pressure of 2.5 MPa for 4- 6 hours