DD258535A3 - METHOD FOR HYDRORAFFINATION OF VISBREAKER DISTILLATES - Google Patents

Abstract

A process is proposed for the hydrorefining of visbreaker distillates mixed with straight-run petroleum distillates in a mixing ratio of 1: 1 to 1: 5, the mixture having a boiling range of 450 to 750 K. The desulfurization is carried out on a catalyst arrangement with catalysts of the type Ni-Mo-Al2O3. According to the invention, two catalyst zones of the raw material mixture in the presence of hydrogen are successively purged at adiabatic reaction conditions. The catalyst of the first zone has an atomic Ni / Mo ratio greater than 1, the catalyst of the second zone an atomic Ni / Mo ratio less than 1 and additionally 1.5 to 5.0% fluorine. The method is characterized in that a substantial desulfurization and hydrogenation of the diolefins and olefins takes place, while aromatics are hardly hydrogenated and the accumulation of fission products is low.

Description

Field of application of the invention

The invention relates to a process for the hydrocatalytic desulfurization of hydrocarbon mixtures in the boiling range from 450 to 750 K, which contain diolefins, olefins and aromatics.

The process is suitable for the desulfurization of mixtures consisting of thermal decomposition of petroleum residue-derived unstable hydrocarbon distillates, especially visbreaker distillates, and straight-run distillates, with adiabatic reaction at pressures of 3 to 7 MPa and temperatures of 570 to 680 K.

Characteristic of the known technical solutions

Visbreaker distillates in the boiling range 450 to 750 K have relatively high sulfur contents and contain diolefins, olefins, mononuclear and polynuclear aromatics.

Visbreaker distillates are not suitable as blending components for diesel fuels without pretreatment because of the high sulfur content and because of the content of diolefins, which tend to polymerize and thus adversely affect the storage stability. To reduce the sulfur and Diolefinehaltes a hydrocatalytic treatment is common. Known hydrocatalytic desulfurization are for the processing of Visbreakerdestillaten in mixture with straight-run fractions for the production of diesel fuel components only limited use or their use is uneconomical, since by the use of conventional Ni-Mo-Al2O ₃ catalysts under the required reaction conditions the hydrogen consumption by the partial aromatics hydrogenation and by cracking reactions is high, since the hydrogenation process as a side reaction coke is formed, which deactivates the catalyst progressively and thus allows only short driving periods and because the liberated by the hydrogenation reaction heat restricts the proportion of unstable components in the raw material.

Thus, according to DE-OS 2517231 a process for the hydrogenation of strongly unsaturated heavy hydrocarbon fractions is known which involves the use of Ni-Mo-Al ₂ O 3 catalysts and the raw material is passed in succession over two different catalysts in the presence of hydrogen. The first catalyst may have an atomic Ni / Mo ratio of 1.5: 1 to 10: 1, and the second catalyst may have an atomic Ni / Mo ratio of 0.1: 1 to 1: 1. The proposed method is not very suitable for the production of diesel fuel components, since it refers to raw materials with a minimum content of aromatic compounds of 80 wt .-%, since it works with a combination of catalysts, which has a strong hydrogenating effect, the aromatic content drops sharply, which is associated with a very high hydrogen consumption and a large exotherm, since it does not allow adiabatic reaction, but between the secondary catalyst beds cold hydrogen and / or cold hydrogenated product must be fed to thermally control the process. Furthermore, according to DE-AS 1645739 a process for the hydrorefining of mixtures consisting of unstable and stable hydrocarbon fractions on a conventional catalyst, preferably nickel molybdate on a silica containing alumina carrier known. The untreated stable constituents used according to the invention serve to dilute the reactive and unstable constituents and to absorb the heat of reaction liberated during the hydrogenation. The process is suitable for the production of cracking raw materials since polycyclic aromatic compounds are converted into easier crackable naphthenes, but the process is not very suitable for the production of diesel fuel components because it prescribes a particular raw material composition which only a few users can satisfy. since the hydrogenation of the aromatics is associated with a high consumption of hydrogen, since due to the high degree of hydrogenation liberated heat of reaction greatly limits the use of unstable components in the raw material.

Since the cost of producing one kilogram of hydrogen is much higher than the price of one kilogram of diesel fuel (ten times as much), it is advantageous for economic reasons to obtain diesel fuel components with as little hydrogen consumption as possible.

Object of the invention

The object is a process for the hydro-refining of visbreaker distillates in admixture with straight-run fractions capable of producing diesel fuel components of the low sulfur content range 450 to 750 K and having sufficient storage stability in a particularly economical manner.

Explanation of the essence of the invention

The object is to develop a simple catalytic process for the hydrorefining of visbreaker distillates in a mixture with straight-run distillates, which allows an adiabatic reaction and operates with low hydrogen consumption and largely avoided in the cracking reactions that lead to coke formation and the formation of short-chain hydrocarbons be so that a long-term stability of the catalyst is ensured.

This object is achieved by a method for the hydrorefining of visbreaker distillates in admixture with straight-run petroleum distillates, wherein the mixture boils in the temperature range of 450 to 750 K at normal pressure, on a catalyst arrangement with catalysts of the type Ni-IVIo-AI ₂ O ₃ , the a particle density of 0.90 to 1.30 g / cm ³ , solved by inventively two catalyst zones in succession from a visbreaker distillate straight-run petroleum distillate mixture in the volume ratio of 1: 1 to 1: 5 at adiabatic reaction conditions in cocurrent Hydrogen flows through it by the catalyst of the first zone in a conventional manner contains a catalyst consisting of extrudate particles with ring profile and an atomic Ni / Mo ratio of greater than 1.0 by the catalyst of the second zone in known manner has an atomic Ni / Mo ratio of 0.2 to 1.0 and (novel in the combination of first and second catalysis Atorzone) additionally contains 1.5 to 5.0% fluorine and also consists of extrudate particles with a V voices of 45 to 60% and a surface volume ratio of 3.5 to 10 mm " ¹ , by the nickel of the second catalyst zone before sulfurization is basically present as a disperse yellowish NiMoO ₄ , which by impregnation of the carrier moldings successively with [Ni (NH ₃ ) _e ] (OH) ₂ - or [Ni (NH ₃ ) 6] CO ₃ solution and (NH ₄ I ₂ MoO ₄ at an intermediate annealing was obtained and in that the volume ratio of second to first catalyst zone 3: 1 to 25: 1. Both zones are arranged in a reactor.

An advantage of the method according to the invention is that existing technological devices that are projected, constructed and operated for the desulfurization of straight-run gas oils and usually allow only an adiabatic reaction, with low investment expenditure also for the processing of Visbreakerdestillaten in a mixture with straight- Run-distillates can be operated at mixing ratios up to 1: 1 with high desulfurization and at relatively low hydrogen demand.

It has surprisingly been found that Visbreakerdestillate in a mixture with straight-run gas oil at known physical reaction conditions according to the method of the invention can be desulfurized by passing over a catalyst arrangement to a high degree without a significant hydrogenation of the aromatics takes place that a hydrogenating the Diolefins and olefins take place without cracking reactions which lead to coke formation and formation of short-chain hydrocarbons, which are to be expected especially when acid catalysts and unstable constituents are used in the raw material under refining conditions.

embodiments

The raw material 1 is a mixture of visbreaker distillate and straight-run gas oil in a mixing ratio of 1: 1, as raw material 2, a mixture of the same components in the mixing ratio 1: 4.2 and the product characteristics according to Table 1 for Hydroraffinationsversuche on a small scale (raw material 250 ml / h) used.

Table 1

raw material kg / m ³ 1 2 Density at 293 K K 862 850 Initial boiling point K (bei98Vol .-%) 455 451 Final boiling point Wt .-% 700 693 sulfur content mgNH ₃ / l 1.51 1.05 Base salary GBR / 100g 175 95 bromine number Wt .-% 28.3 14.5 aromatics 37.5 32.5

example 1

The raw material 1 is passed in a refining trial under the process parameters set forth in Table 3, column 1 over a catalyst according to Table 2, column A. After 240 operating hours at 323 KH ₂ S-stripped and subsequently analyzed.

The analysis results are in Table 4, column A.

Example 2

The raw material 1 is passed in a second refining trial under those set forth in Table 3, column 1 process parameters over a catalyst according to Table 2, column B.

After 240 hours of operation, a raffinate sample was taken, stripped with nitrogen at 323 KH ₂ S-free, and subsequently analyzed. The analysis results are shown in Table 4, column B.

Example 3

The raw material 1 is passed over two catalyst zones according to the process of the invention and those set forth in Table 3, column 2 process parameters. The first contains the catalyst according to Table 2, column A and the second the catalyst according to Table 2, column B. The volume ratio of second to first zone is 5: 1.

After 240 hours of operation, a raffinate sample was taken, stripped with nitrogen at 323 KH ₂ S-free, and subsequently analyzed.

The analysis results are in Table 4, column C.

Example 4

The raw material 1 is passed in a fourth refining trial and those described in Table 3, column 2 process parameters over two catalyst zones. The first contains the catalyst according to Table 2, column A and the second the catalyst according to Table 2, column C. The volume ratio of second to first zone is 5: 1.

After an operating time of 240 h, a raffinate sample is taken, stripped with nitrogen at 323 KH ₂ S-free and subsequently analyzed. The results of the analysis are shown in Table 4, column D. The catalyst according to Table 2, column C is commercially available and corresponds to the prior art. It was prepared by impregnating annealed Al ₂ O ₃ preforms with NiNO ₃ and (NH 4) IVoCu solution.

Example 5

The raw material 1 is passed in a fifth refining trial under the process parameters set forth in Table 3, column 1 over a conventional catalyst according to Table 2, column C. After 240 hours of operation, raffinate was removed, stripped with nitrogen at 323KH ₂ S-free, and analyzed. The analysis results are in Table 4, Column E.

Example 6

The raw material 2 is passed in accordance with the process uY according to the invention over the process parameters set forth in Table 3, column 2 over two catalyst zones according to Example 3. After 240 hours of operation, a raffinate sample was taken, stripped with nitrogen at 323KH ₂ S-free, and subsequently analyzed. The analytical results are in Table 4, column F.

Example 7

The raw material 2 is passed over two catalyst zones according to the process of the invention and those set forth in Table 3, column 2 process parameters. The first contains the catalyst according to Table 2, column A, and the second the catalyst according to Table 2, column D. The volume ratio of second to first zone is 25: 1.

After 240 hours of operation, a raffinate sample was taken with nitrogen stripped at 323K H ₂ S free and subsequently analyzed.

The analysis results are in Table 4, column G.

Table 2 mm A B C 1.6 D 1.5 mm extrudate Extrudate vortex Profile 3-6 3-5 catalyst composition kg / m ³ circular profile 670 630 column cnrVg 1.8 1.6 Ό, 60 0.63 shape g / cm ³ 4-6 3-6 1.25 1.07 Wt .-% 500 650 4.4 6.7 diameter Wt .-% 0.80 0.55 20.2 16.3 length Wt .-% 1.05 1.20 1.7 1.4 bulk weight Wt .-% 8.2 4.5 2.0 4.9 pore volume 5.1 20.3 0.5 0.9 particle 1 mm 2 1.5 3.2 9.7 Ni content 0.001 2.0 Al ₂ O ₃ Al ₂ O ₃ MoO ₃ content 3.7 0.5 SiO ₂ content 3.0 5.0 F content Al ₂ O ₃ Al ₂ O ₃ Ni / Mo ratio O / V ratio support material

Annotation:

Catalysts B and D are prepared by soaking shaped Y-Al ₂ O ₃ particles containing 2% SiO ₂ with an ammoniacal (Ni (NH ₃ ) ₆ ) CO ₃ solution, draining the impregnation solution, and molding are dried and calcined and then impregnated with a (NH ₄ I ₂ MoO ₄ - and NH ₄ F solution and dried.

Table 3 K / m ³ 1 B ,8th C 2 D e F G experimental parameters MPa H 623 842 851 589 847 838 841 842 column m ³ iN 3 411 444 3.8 418 412 438 440 Reactor inlet temperature kg / kg · 200 712 2 695 200 710 718 688 683 reactor pressure Vol .-% 42 0.09 0.10 42 0.22 0.18 0.08 0.06 Gas raw material ratio 80 27 29 76.1 57 53 9 7 Catalyst load ¹¹ Ni + Mo on the catalyst 8.2 1.9 2.9 2.8 2.0 2.3 H ₂ in the hydrogenation gas 38.4 36.4 30.4 24.9 31.3 30.9 ¹¹ mass ratio of raw material to 8.9 2.0 6.1 8.7 2.4 2.1 Table 4 A 93.8 99.0 95.8 91.4 98.7 99.0 Raffinatbeschaffenheit 836 column 421 Density / m ³ 691 Initial boiling point K 0.49 Siedende K 147 Sulfur content Ma .-% 3.7 Base content mgNH ₃ / l 32.1 Bromine number g Br / 100g 2.1 Aromatic content Ma .-% 98.2 Fission content 455 K Ma .-% Liquid yield% by volume

The experimental results show that in the catalyst arrangement according to the inventive method (Example 3, 6 and

7) the lowest cleavage rates, the lowest density drop and the lowest aromatics upheavals are observed, taking into account the liquid yields. From this it can be seen that in example 3, 6 and 7 the hydrogen consumption and the heat of reaction are lower than in the other examples. In Example 2, equally good degrees of desulfurization are achieved as in Example 3, but these values are achieved at a higher reactor inlet temperature and with a significantly lower liquid yield of raffinate, based on the use of raw materials. Prior to the experiment, the reactor charges in all 7 examples were sulfurized in the same way with sulfur-containing straight-run distillate.

After a running time of 250 h, the catalysts were burned in the air stream and determined from the resulting CC> 2 mass of the coke content of the catalyst.

The coke content was, based on the catalyst mass, at

example 1 9,3Ma .-% Example 2 14,2Ma .-% Example 3 5,7Ma .-% Example 4 12,1Ma .-% Example 5 13.1% by mass Example 6 5,0Ma .-% Example 7 5.2mA .-%

Claims (1)

- 1 - ^ DO DJO Invention claim: Process for the hydrorefining of visbreaker distillates mixed with straight-run petroleum distillates, the mixture boiling in the temperature range of 450 to 750 K at normal pressure, on a catalyst arrangement consisting of two zones, with catalysts of the type Ni-Mo-Al ₂ O ₃ , which have a particle density of 0.90 to 1.30 g / cm ³ , and the volume ratio of second to first catalyst zone is 3: 1 to 25: 1, characterized in that the two catalysts in succession from a mixture of Visbreakerdestillaten and straight-run -Diffused in the volume ratio of 1: 1 to 1: 5 at adiabatic reaction conditions in cocurrent flow with hydrogen, that the first catalyst zone in a conventional manner contains a catalyst consisting of Extrudatteilchen with ring profile and its atomic Ni / Mo ratio greater than 1, the second catalyst zone is extrudate particles having a surface / volume ratio of 3.5 bi 10 mm ^"1 and a void volume of from 45 to 60% is that the catalyst of the second zone in a conventional manner having an atomic Ni / Mo ratio of 0.2 to 1.0 and additionally based on the total composition 1.5 contains up to 5.0% fluorine, that in the catalyst of the second zone before sulfurization, the nickel is basically present as a disperse yellowish NiMoO ₄ , which by impregnation of the carrier moldings successively with [Ni (NH ₃ J ₆ ] (OH) ₂ - or [Ni (NH ₃ ) ₆ ] CO ₃ solution and (NH ₄ ) ₂ MoO ₄ solution was obtained during an intermediate annealing.