RU2496574C1 - Catalyst for hydrofining diesel fractions - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention relates to catalysis. Described is a catalyst for hydrofining diesel fractions, which contains molybdenum disulphide, cobalt, nickel or iron, pseudoboehmite γ-AlOOH, obtained from electroexplosive aluminium nitride, which contains as a modifying additive nanodiamonds with size of not more than 20 nm, with the following ratio of components, wt %: pseudoboehmite - 10, nanodiamonds - 20, cobalt, nickel or iron - 20-30, molybdenum disulphide - the balance.

EFFECT: high mechanical stability of the catalyst.

2 cl, 1 tbl, 5 ex

Description

The invention relates to the field of oil refining, in particular, to catalysts for the production of motor fuels. Catalysis by nanoparticles of metals immobilized on solid supports is one of the most important directions in the development of catalytic science and catalytic technologies in the 21st century. In the field of hydrotreating fuel fractions, one of the methods allowing the formation of an active metal-sulfide Co (Ni) / Mo (W) -S phase is the deposition of the corresponding precursors of active components from salt solutions with the addition of chelating agents (nitrilotriacetic acid, ethylenediaminetetraacetic and cyclohexanediaminopentaacetic, citric and thioglycolic acids, as well as heteropoly acids) [Startsev A.E. Sulfide Hydrotreating Catalysts: Synthesis, Structure, Properties. - Novosibirsk: Science. 2007. - 203 p .; Tomina N.N., Pimerzan A.A., Moiseev I.K. Sulfide catalysts for hydrotreating oil fractions // Russian Chemical Journal. - 2008. - T. LII. - No. 4. - S. 41-52; Pashigreva A.V., Bukhtiyarova G.A., Klimov O.V., Noskov A.S., Polunkin Ya.M. Deep hydrotreating of oil distillates of primary and secondary origin on new generation catalysts // Oil Refining and Petrochemicals. - 2007. - No. 10. - S.19-23].

The problem of all supported catalysts supported on substrates remains the possible partial ablation of the active component and support in a finely dispersed form in the flow of the working gas (nitrogen, hydrogen) at high temperatures and pressures. Meanwhile, the maximum catalytic activity was established just for the form of the catalyst with weak binding of the active component to the substrate [Antony Stanislaus, Abdulazeem Marafi, Mohan S. Rana. Recent advances in the science and technology of ultra low sulfar diesel (ULSD) production. Catalysis Today. - 2010. - 153. P.1-68]. This problem becomes even more urgent for massive nanoscale catalysts prepared on the basis of solid-phase precursors. The volatility and entrainment of nanopowder components is very difficult to control. The result of this effect can be observed indirectly when, after some time of operation of the units, the corresponding capillaries of the working, monitoring and measuring equipment become clogged, and, as an inevitable consequence, the catalyst activity decreases due to entrainment of the active phase. So the question of creating nanoscale catalytic hydrotreating systems with an even higher level of activity, characterized by an increased level of structural organization and stability over time, remains unresolved. It was previously established that the adsorption properties of detonation synthesis nanodiamonds are not inferior to many carbon sorbents in adsorption properties; there are a number of advantages: nanodiamonds have catalytic activity and abrasive ability. Each nanodiamond particle consists of a single-crystal diamond core (core) and a graphite shell, on the surface of which there is a functional cover (carboxyl, hydroxyl groups, etc.) [6]. [Eremenko A.N., Besedina O.A., Obraztsova I.I. // ZhPKh. 2004. V.77. No. 12. S.1956-1959.]. Nanodiamonds have a high specific surface, their particles have nanometric sizes, are characterized by the hydrophilic nature of the surface, on which there is an abundance of electrons (this is a multiple donor radical), and the "core" of the nanodiamond is chemically inert. A catalyst for the oxidation of carbon monoxide is described, containing a porous oxide carrier, one or more catalytically active metals of the platinum group and nanodiamond, on which clusters of the catalytic metal of the platinum group are fixed in the following ratio of components (wt.%): Catalytically active metal - 0.05-1 0; nanodiamonds - 0.5-5.0; porous oxide carrier - the rest. A method for producing the above catalyst is also described, which consists in impregnating a porous oxide support with an aqueous suspension of nanodiamond with clusters of a catalytically active platinum group metal attached to it and ultrasonically processing it at a temperature of 50-80 ° C for 30-60 minutes and then drying at a temperature of 100-150 ° C. EFFECT: obtained catalyst is highly effective in the conversion of carbon monoxide to carbon dioxide in air at temperatures from 0 to 50 ° C and a range of CO concentrations from 1 to 1000 ppm. [Patent RU 2411993 C1].

Closest to the claimed invention is a catalyst capable of providing an ultra-low level of residual sulfur in hydrodesulfurizates [Patent No. 2445163], which contains commodity molybdenum and / or tungsten disulfide or obtained by the method of self-propagating high temperature synthesis (SHS), with a carrier - nanosized pseudobeam in a ratio of 20:80 or without it, the constituent components of which during the manufacturing process are subjected to mechanochemical effects in vertical vibration mill, under a vacuum of 10 ^-5 Torr, with a frequency and amplitude of exposure of 16 Hz and 2 mm, respectively, and an activation time of 4-12 hours. The catalyst contains a promoter, which is used nanopowders of 3d metals (Ni, Co, Fe) obtained by electrophysical methods, with a ratio of the active component and promoter of 30:70 with a particle size of less than 100 nm, and, in addition, a gas-phase Ni nanopowder in a pyrocarbon shell , with a particle size of less than 10 nm in an amount of 3% of the active component.

The disadvantages of the prototype are - an insufficient level of mechanical and structural strength, which leads to the formation of a fine catalyst fraction, subject to entrainment under conditions of high pressure and temperature, and, as a result, (along with other possible reasons) - a decrease in the level of catalyst activity over time, as well as the need the use of only nanosized metal powders obtained by the method of electric explosion of a conductor or gas-phase synthesis, which entails the complication and cost of the procedure for their manufacture ovalization.

The objective of the invention is to obtain in one stage a highly efficient multifunctional catalyst for hydrotreating diesel fractions, characterized by high mechanical stability, increased catalytic activity and availability of feedstock.

The technical result of the invention consists in increasing the mechanical stability of the catalytic system, lowering the working temperature of hydrotreating due to the use of nanoscale diamonds in its composition, and also the ability to use not only nanoscale powders of cobalt and nickel obtained by electric explosion of a conductor and gas-phase synthesis [Patent No. 2445163], but also commercial, coarse powders of the same metals of micron sizes.

The technical result is achieved in that the catalytic mixture contains abrasive detonation nanodiamonds (ON) with a size of not more than 20 nm, pseudoboehmite (γ-AlOOH) and coarse powders of molybdenum disulfide (active component), cobalt, nickel or iron (as promoters) of micron size 2 -30 μm with a ratio of γ-AlOOH: HA: Co (Ni, Fe): MoS ₂ = 10: 20: 20-30: 50-40 (% wt.), Which undergo nanofragmentation during the mechanochemical combination (the average particle size becomes 50-100 nm); as well as pseudoboehmite obtained from electroexplosive aluminum nanopowder. In this case, nanodiamonds provide additional structuring of the mixture, increase the activity of the catalyst due to its own hydrodesulphurizing and hydrogenating ability.

The catalyst is obtained from the following components: coarse-dispersed commercial molybdenum disulfide (for example, DMI-7) is used as the active component, industrial powders of cobalt, nickel, micron-sized iron are used as promoters, detonation nanodiamonds with a particle size of 2-20 are used as a modifying additive nm, and the binder is pseudoboehmite γ-AlOOH, which, in turn, is obtained from electroexplosive aluminum nitride.

The method for producing the catalyst includes a one-stage solid-phase mechanochemical activation of the components in a vertical vibration mill, under a vacuum of 10 ^-5 Torr with a frequency and amplitude of exposure of 16 Hz and 2 mm, respectively, and an activation time of 4-12 hours; the product is stored in an inert atmosphere of argon. The catalyst is prepared in the form of tablets by compression under a pressure of 250 kg / cm ² , which are then crushed and sieved through sieves, taking a fraction of 0.5-4 mm.

The specified fraction of the catalyst is loaded into the reactor flow-through catalytic installation of hydrotreatment, providing a layer height of 6 mm Test conditions for laboratory flow-through installation - hydrogen pressure 4.0 MPa; H ₂ / feed ratio = 400: 1; feed rate of 40 ml / hour (as in the prototype); T = 390 ° C (temperature range of the hydrotreatment catalysts is 340-400 ° C). The activity of catalytic systems in hydrotreating processes is estimated by the value of the residual content of sulfur, nitrogen, and aromatic hydrocarbons (AC) in hydrodesulfurizates. The elemental content of sulfur and nitrogen was determined on an Antek analyzer. The hydrogenating ability of the catalysts was assessed by ¹ H NMR by the change in the proportion of aromatic protons in hydrodesulfurizates in comparison with the initial diesel fraction, followed by recalculation of the change in the content of aromatic hydrocarbons in%.

Hydrodesulfurizates are selected (after the preparatory steps are completed, the unit is pressed, the catalyst is dried, the catalyst is wetted and activated) at two temperatures of 340 and 390 ° C at two times - 1 hour after the process enters the operating mode and after 10 hours of operation of the catalytic layer.

The catalyst efficiency tests were carried out on a straight run diesel fraction of the Ryazan Oil Refinery (temperature range 180-360 ° C; density 0.866 g / cm ³ , total sulfur content 1.18%; total aromatics content 30.86%; nitrogen 138 ppm); the sulfide sulfur content of 0.4%.

Examples of specific performance.

Example 1. The composition catalyst is 2.0 g (20%) of cobalt powder, 2.0 g (20%) of nanodiamonds, 1.0 g of pseudoboehmite (10%), 5.0 g (50%) of molybdenum disulfide are loaded into a steel mortar of a vertical vibrating mill, quantity powder in one load - a total of 10 g, balls are made of steel, the mass of balls is 200 g. Air is pumped out of a mortar with balls and powder to a level of 10 ^-5 Torr, then the mortar is fixed on a frame that vibrates with a frequency of 16 Hz and an amplitude of 2 mm . Activation time 4 hours. The granular form of the catalyst is prepared by separating and separating a certain fraction in the form of granules of the desired size, which is placed in the reactor of a flow-through hydrotreatment unit. Hydrodesulfurization is taken after 1 hour and after 10 hours for operating temperatures of 390 and 340 ° C.

Example 2. The catalyst is similar in composition as in example 1, only nickel powder is taken instead of cobalt powder and hydrodesulfurizate is sampled after 1 hour only for a temperature of 390 ° C. The results are presented in the table.

Example 3. The catalyst composition is 3.0 g (30%) of nickel powder, 2.0 g (20%) of nanodiamonds, 1.0 g of pseudoboehmite (10%), 4.0 g (50%) of molybdenum disulfide are prepared and used in the hydrotreating process as example 1 (table 1).

Example 4. The composition of the catalyst is similar to example 1, only instead of cobalt powder, iron powder is taken (Table 1).

Example 5. The catalyst composition is 3.0 g (30%) of cobalt powder, 2.0 g (20%) of nanodiamonds, 1.0 g of pseudoboehmite (10%), 4.0 g (50%) of molybdenum disulfide are prepared and used in the hydrotreating process as example 1 (table 1).

Thus, the proposed catalyst is characterized by greater catalytic activity in the hydrotreatment processes, due to which the process temperature decreases by 50 ° C, while providing an ultra-low content of residual sulfur and nitrogen and a decrease in the amount of aromatic hydrocarbons.

Table 1 Sulfur content in the initial diesel fraction 11800 ppm, nitrogen 138 ppm Example No. T, ° C Residual Content The decrease in the content of AC, in%, 1 h S ppm N ppm Process time 1 hour 1 hour 10 h one 390 48 46 55 8 340 53 55 fifty 13 2 390 49 - 33 10 3 390 52 52 25 5 340 47 44 23 fifteen four 390 86 87 79 8 340 72 72 85 10 5 390 10 12 fifteen 8 340 fifteen fifteen fifteen eighteen

Claims (2)

1. The catalyst for hydrotreatment of diesel fractions containing molybdenum disulfide, cobalt, nickel or iron, γ-AlOOH pseudoboehmite obtained from electroexplosive aluminum nitride, characterized in that it contains nanodiamonds no larger than 20 nm in size as a modifying additive, in the following ratio of components, wt.%:
Pseudoboehmite 10 Nanodiamonds twenty Cobalt, Nickel or Iron 20-30 Molybdenum disulfide Rest 2. The catalyst according to claim 1, characterized in that it contains cobalt, nickel or iron in a finely divided state.