CS238793B1 - Process for producing a raw material for catalytic reforming - Google Patents

Abstract

Production of raw material for catalytic reforming or catalytic isomerization from medium-boiling suitably selected two fractions of crude oil during their parallel hydrorefining on mixed sulfide catalysts and redistillation of the hydrorefining products to a fraction up to 180 or up to 220 °C, which is combined with petroleum gasoline before its hydrorefining.

Description

The invention relates to a raw material for catalytic reforming and/or catalytic isomenization of suitably selected medium-boiling fractions of crude oil during their simultaneous hydrorefining on mixed sulfide catalysts under hydrogen pressure and at elevated temperature.

Low-lead motor gasolines are currently the most important product from oil and all available sources are still being sought for their production. Often, primary gasoline from oil boiling above 80 to above 110 °C is not enough as a raw material and the shortage of raw material must be solved in the refinery by supplying it from other sources. This is especially critical in a refinery without cracking processes and with the simultaneous production of aromatic hydrocarbons of high C? and 0θ from the product of catalytic reforming.

In the refinery there is usually an excess of medium-boiling fractions, from which fuels for jet aircraft and diesel engines, or light heating oils, are prepared by hydrotreating. Catalysts for hydrotreating have undergone changes in recent times and, as a result of sophisticated activation and sulfurization processes, have significantly increased service life even under harsh temperature conditions at medium pressures.

The invention solves the problem of supplementing the feedstock for catalytic reforming and possibly also for catalytic isomerization by producing medium-boiling petroleum fractions during their hydrorefining on mixed sulfide catalysts. According to the process according to the invention, two medium-boiling fractions A and B are separated during the distillation of sulfurous crude oil with a distillation range of fraction A: 150 °C to 300 °C and fraction B: 200 to 360 °C. These are fed to parallel hydrotreating units, in whose reactors pellets or extrudates containing cobalt and/or nickel and molybdenum sulfides are stored as catalysts, on a carrier consisting mainly of a refractory metal oxide, especially aluminum, combined with hydrogen gas in a volume ratio of 1:50 to 500 at temperatures on the catalysts in the range of 260 to 350 ^° C for fraction A and 340 to 420 °C for fraction B, with a volume rate of 1 to 6 volumes of fraction per volume of catalyst per hour, at a pressure of 2.5 to 4.0 MPa. The resulting liquid product after separation of the gas phase under pressure is fed to a distillation column, where it is separated at a pressure of 0.01 to 0.2 MPa as a distillate, a raw material for catalytic reforming with the end of the distillation range up to 220 °C, preferably up to 180 °C. Both distillates are combined with equally boiling fractions from the same crude oil in a mass ratio of 1:5 to 50 and is fed through the hydrogenation refining of gasoline, redistillation to the catalytic reforming unit, or the lighter part to the catalytic isoaerization unit.

Preferably, in the process, fraction A has a boiling point of 150 to 220 °C and fraction B has a boiling point of 200 to 360 °C or fraction A has a boiling point of 180 to 300 °C and fraction B is formed from a mixture of fraction 180 to 300 °C and fraction 280 to 360 °C in mass ratios of 2:1 to 1:3.

The catalyst carrier contains mainly gamma alumina and a small amount of impurities, such as SiO ² . The hydrogen gas produced preferably contains 85 to 96 vol. % hydrogen in addition to light hydrocarbons C 1 to C 2 . The reaction pressure is preferably 3 to 4 MPa and the preferred reaction temperature for fraction B is 360 to 420 °C. The resulting feedstock for catalytic reforming has 3 to 15 t wt. more cyclanes than the gasoline fraction of the same boiling point from the same crude oil.

From the complex scheme of production of raw material for catalytic reforming according to the invention, the main features leading to higher effects than the current common scheme of processing middle fractions from crude oil can be identified in the analysis. These are the distillation ranges of fractions A and B in both alternatives, as well as the combination of reaction temperatures, pressure and partial pressure of hydrogen.

This is in contrast to the usual process, where the kerosene fraction and the diesel fraction are isolated and desulfurization is carried out at lower pressures and lower partial pressures of hydrogen and at lower temperatures, producing a small amount of secondary gasoline, especially from the diesel fraction. The secondary gasoline thus produced is often then sent to less advantageous further processing than reforming and aromatics production.

The example below illustrates the characteristics of the invention.

Example

In a refinery with a capacity of 3 million tons of sulfurous crude oil per year, 63 tons of gasoline and 110 tons of middle distillates are obtained per hour - distillate A with a boiling point of .80 to 300 °C 60 tons and distillate B with a boiling point of 280 to 360 °C 50 tons. Part of distillate A according to the invention was fed to one hydrorefining unit, in which a cobalt-molybdenum catalyst on gamma alumina in 5x5 mm tablets was stored. The second part of distillate A and distillate B in a ratio of 1:2 were fed to a second hydrorefining unit with the same catalyst. The conditions on both units are given in Table 1. The products from both units were fed into approximately 30 tray columns, where at a pressure of .00 kPa, gasolines were obtained in an amount of approximately 1.5 to 3.0 t/h, with the properties given in Table 2. It is evident that the gasolines have a distillation range close to heavy gasoline from crude oil, only the content of cyclanic hydrocarbons is slightly increased, as they are secondary products.

The naphthene content is distorted by dilution with light hydrocarbons up to (beginning of distillation), which enter the gasolines from the supplied reforming hydrogen gas. In heavy gasoline, with an initial boiling point of around .00 °C, an increase in the concentration of naphthenes by 3 to 5% relative can be expected. The gasolines were combined with petroleum gasoline and led with it through hydrorefining, redistillation to the reforming unit, where the amount of gasoline pushed through could be increased by 5 to 6% by weight. At elevated temperatures to 380 °C and pressures to 3.5 to 4.0 MPa, with the processing of fractions A and B, up to 10% of new secondary heavy gasoline could be obtained, mainly used for the reforming unit. Secondary gasoline had an increased yield and an increased cyclane content of 5% by weight. Gasoline gave a higher octane number by 2 units during reforming at the same pressure and temperature parameters.

Table!

Conditions for production of raw material for reforming from medium fractions unit no. 1 2 fractions A B

ratio - , :2 temperature, °C 320 340 pressure, MPa 2.9 2.95 volume speed, h ^- ' 3.5 2.5 gas to feedstock ratio by volume 1:240 1:450 % vol. Hg in gas 86.5 87

Table 2 Gasoline quality unit no. generated from the cleavage of medium fractions 1 under the conditions of Table 1. • 2 compare heavy ^d 20 -· 0.742 0.750 gasoline py 0.750 from the year- start dist., °C 84 77 105 .0% vol. 1.5 122 115 50% vol. 128 138 135 95% vol. 142 156 173 k. d. °C/% vol. ,55/97 163/97 181/99

Table 2 continued

unit no. 1 2 compare heavy petroleum gasoline aromatics, % wt. 9.6 10.9 10.0 olefins, wt.% 2.24 2.86 0.1 naphthenes, wt.% 26.7 29.1 26.2 paraffins, % wt. 61.5 57.1 63.7

SUBJECT OF THE INVENTION

Claims (5)

1. A process for producing a feedstock for catalytic reforming and, if necessary, a process for producing a feedstock. catalytic isomerization from medium boiling petroleum fractions by hydrotreating them on mixed sulphide catalysts, characterized in that, in the distillation of sulfur oil, two medium boiling fractions A and B are separated with distillation ranges of fractions A of 150 to 300 ° C and of fractions B of 200 to 360 ° G, which are fed to parallel hydrotreated units, in whose reactors are pelletized catalysts or extrudates containing cobalt and / or nickel and molybdenum sulphides, on a carrier consisting predominantly of a refractory metal oxide, in particular aluminum, together with a 1:50 to 50% hydrogen gas 500 v / v at catalyser temperatures ranging from 280 to 350 ° C for fraction A and 340 to 420 ° C for fraction B, with a flow rate of 1 to 6 volumes of fraction per catalyst volume per hour at a pressure of 2.5 to 4, 0 MPa and the resulting liquid product after separation of the gas phase under pressure is fed to a distillation column where it is separated at a pressure of 0. As distillate feedstock for catalytic reforming and at the end of the distillation range up to 220 ° C, preferably up to 180 ° C, the two distillates are combined with the same boiling gasoline fractions from the same oil in a ratio of 1: 5 to 50 mass and via gasoline hydrotreating and after re-distillation to catalytic reforming unit, eventually lighter part to catalytic isomerization unit. 2. The process according to claim 1, wherein fraction A preferably has a boiling point of 150-220 [deg.] C and fraction B a 200-360 [deg.] C or fraction A has a boiling point of 180-300 [deg.] C and fraction B is formed from a mixture of fraction 180 to 300 ° C and fractions 280 to 360 ° C in ratios of 2: 1 to 1: 3 by weight. 3. The process of claim 1 wherein the catalyst support comprises predominantly gamma alumina and a small amount of dopants such as SiO2, FegOp SO3. 4. A process according to any one of claims 1 to 3, characterized in that the hydrogen gas preferably contains 85 to 96% by volume of hydrogen in addition to the light hydrocarbons C until the reaction pressure is preferably 3 to 4.0 MPa. 5. The process according to claims 1 to 4, characterized in that the temperature for fraction B is preferably maintained between 360 and 420 [deg.] C.