CS264615B1 - Improving the quality of petroleum distillates - Google Patents

Abstract

Method for improving the quality of petroleum distillates, especially gasoline, kerosene and diesel fuel, by hydrotreating sulfur and nitrogen compounds of unsaturated and aromatic hydrocarbons at a pressure of 2.5 to 5.0 MPa and a throughput of 1.0 to 6.0 h-·*· in the presence of extruded alumina-based catalysts containing metals of groups VI and VIII of the periodic table, wherein extrudates of 1 to 2 mm in diameter based on cobalt and molybdenum are prepared by coextrusion with aluminum hydrate of a boehmite or pseudoboehmite structure with a C0M0O4 crystal size below 50 8 and hydrotreating is carried out at a temperature of 280 to 360 °C.

Description

The invention relates to improving the quality of petroleum distillates by hydrotreating sulfur and nitrogen compounds and hydrogenation of aromatics using catalysts in the form of fine-grained extrudates with a diameter of 1 to 2 mm and the shape of three- or four-leaf clovers prepared by coextrusion of aluminum hydrate in the form of boehmite or pseudoboehmite and catalytically active metals of groups VI and VIII of the periodic table.

Currently, hydrotreating in a hydrogen stream using Co-Mo-alumina or Ni-Mo-alumina catalysts is used to improve the quality of petroleum distillates and various hydrocarbon fractions, the activity of which, expressed in the conversion of sulfur and nitrogen compounds, does not reach a satisfactory level of quality. These catalysts, used in the production of gasoline, kerosene, diesel fuel, etc., do not provide products of the required quality.

In order to achieve increased quality of these products, it is often necessary to work at increased temperature or pressure, and it is necessary to regenerate the catalyst more frequently, which places increased demands on energy, or investment and maintenance costs of the equipment used, or even increased hydrogen consumption.

However, it has now been found that in the processing of petroleum distillates and the production of gasoline, jet kerosene, diesel fuel, etc., it is possible to achieve an increased degree of desulfurization and degradation of nitrogen compounds by hydrorefining in a hydrogen stream at significantly lower temperatures and lower pressure losses in the reactor, thereby extending the entire operating cycle.

A method of improving the quality of petroleum distillates, in particular gasoline, kerosene and diesel fuel by hydrotreating sulfur and nitrogen compounds, unsaturated and aromatic hydrocarbons in the presence of a catalyst in the form of alumina-based extrudates containing metals of groups VI and VIII of the periodic table, in which gasoline fractions boiling in the range up to 200 °C or kerosene fractions boiling in the range 140 to 250 °C or diesel fuel boiling in the range 140 to 360 °C are treated in a stream of hydrogen gas at a pressure of 2.5 to 5.0 MPa and a throughput of 1.0 to 6.0 h, according to the invention, consists in that heavy diesel fuel containing 5 to 15 wt. parts boiling in the range of 350 to 360 °C are hydrorefined at a desulfurization degree of 85% and at a temperature of 280 to 360 °C on a catalyst in the form of extrudates with a diameter of 1 to 2 mm based on cobalt or/and Ni and molybdenum or/and W prepared by coextrusion with aluminum hydrate of boehmite "3" or pseudoboehmite structure with a pore volume of 0.35 to 0.70 cm /g and with a crystal size of CoMoO^ below 50 8. Before starting hydrorefining, the catalyst is treated with a mixture of hydrogen and sulfur in a molar ratio of 80 to 600 with a gradual increase in temperature in the range of 20 to 400 °C.

In this method of processing petroleum distillates, catalysts based on alumina and metals of groups VI and VIII of the periodic table are used, especially based on Co-Mo-alumina and Ni-Mo-alumina or Co-Ni-Mo-alumina in the form of fine-grained extrudates with a diameter of 1 to 2 mm and profiled into the shape of three- or four-leaf cylinders, prepared by coextrusion of aluminum hydrate from alumina, especially aluminate, alkoxide or chloride, in the form of boehmite or pseudoboehmite. The catalyst mass is prepared by peptization with organic or inorganic acid and a soluble cobalt or/and nickel compound and gradual neutralization of the plastic mass thus formed with ammonium molybdate or ammonium tungstate compounds.

This catalyst preparation procedure enables the decomposition of ColNO^ upon thermal activation to form cobalt aluminate or cobalt molybdate with very small crystal grains below 50 8, or with an amorphous structure. As the size of the CoMoO^ crystallites decreases, the activity of the catalyst increases.

Peptization of the catalytic mass can be carried out with an aqueous solution of acetic acid and cobalt nitrate or nickel nitrate, followed by gradual neutralization with an aqueous solution of ammonium molybdate.

The essence of the invention therefore lies in the high efficiency of catalysts based on Co-Mo-alumina or Ni-Mo-alumina or Co-Ni-Mo-alumina prepared by the above-mentioned process and formed into the shape of fine-grained extrudates in the shape of a trefoil or four-leaf clover, thereby achieving increased desulfurization and denitrogenation activity in the processing of petroleum distillates under mild operating conditions.

These catalysts contain 14 to 25 wt. % MoOj, 3.5 to 5.0 wt. % CoO, 0.0 to 2.5 wt. % SiO ₂ , 0.01 to 0.1 wt. % Na ₂ 0 and the balance Al ₂ Oj. Or 14 to 25 wt. % MoC> ₃ , 3.5 to 10 wt. % NiO, 0.0 to 2.5 wt. % SiO ₂ , 0.01 to 0.1 wt. % Na ₂ <3 and the balance Al ₂ O ₃ . Or 11 to 25 wt. % Mo0 ₃ , 2.5 to 5.0 wt. % CoO, 0.5 to 2.5 wt. % NiO, 0.0 to 2.5 wt. % SiO ₂ ,

0.01 to 0.1 wt. % Na.,0 and the rest Al ₂ O ₃ o

These catalysts exhibit a high specific surface area of approximately 180 to 250 m/g, a high strength of 3 in brrtu mm. 10 N, a total pore volume of approximately 0.35 to 0.70 cm/g, an average pore radius of 25 to 70 ΐ and a CoMo0 ₄ crystal size below 50 8.

These catalysts further exhibit increased porosity and bulk density in the range of 600 to 800 g/l.

Using these catalysts, a high degree of hydrotreating of S- and N-compounds, hydrogenation of unsaturated hydrocarbons and aromatics can be achieved.

Quality indicators can be improved, for example, for kerosene, such as the luminescence number, the height of the soot-free flame, and for diesel fuel, the crystallization point, diesel index, etc.

Using these catalysts, a high degree of desulfurization is achieved using a relatively low hydrotreating temperature, a low hydrogen partial pressure, and a high throughput. A smaller reactor pressure drop can also be achieved, thereby extending the operating cycle and catalyst life.

Example 1

The primary petroleum fraction was hydrotreated in a flow-through pressure reactor with hydrogen at a pressure of 3 MPa using the process according to the invention on a nickel-molybdenum catalyst (A) prepared by coextrusion. The volume of the catalytic bed was 100 cm3, the reaction temperature was 300 °C and the volumetric rate was 2.0 h. The ratio of hydrogen to raw material was 300:1 m _n /m. Before the experiment, the catalyst was sulfurized with a mixture of hydrogen and hydrogen sulfide containing 1.0 vol. % H ₂ S so that the catalyst was gradually heated in the stream of the above mixture to a temperature of 410 °C. After sulfurization, the temperature was reduced to 300 °C and the injection of raw material was started. And the gas mixture was replaced with technically pure hydrogen.

For comparison, the petroleum fraction was hydrotreated using the same procedure on a nickel-molybdenum catalyst (B) prepared by coprecipitation and also on a nickel-molybdenum catalyst (C) prepared by double carbonation of the carrier - active alumina with solutions of active metals.

The properties of the starting kerosene fraction were as follows:

Density/20° 786 kg/m² Sulfur content 0.130% mass Distillation test Smoky flame height 24.2 mm start dest. 155°C Luminometric number 57.2. 5% vol. 165, °C Aromatic content by UV spectrometer: 10% vol. 167°C monoaromatics 20.8 % 50% vol. 180°C diaromatics 0.54 : % 90% vol. 197°C Bromine Index 690 mg Br/100 end of dist. °C/% vol. 213°C/99

Properties of catalysts: A B C bulk weight g/1 700 780 710 MoO^ wt.% 18.0 18.2 17.8 NiO % wt. 4.5 4.3 4.2 At ₂₀ % wt. 0.02 0.09 0.08

The catalysts were used for the tests in a granular state (grain size 1 to 2 mm).

Hydrotreating test results:

Catalyst A B B+ C Exhaust features: sulfur % wt. 0.000' 6 0.002 5 0.001 2 0.000 height of non-soaking flame mm 25.8 25.0 25.3 25.5 luminometric number 60.0 58.0 58.7 58.6 Aroma content: monoaromatics % 15.7 18.2 17.5 16.0 diaromatics % 0.09 0.15 0.12 ' 0.10 Bromine index mg Br/100 g 62 105 90 73

+ the experiment was performed at a temperature of 320 °C

The process of refining the petroleum fraction with a coextruded nickel-molybdenum catalyst gave better results than the catalyst prepared by co-precification or the catalyst prepared by carbonation, which is expensive to prepare. The process with the catalyst prepared by co-precification (B) did not achieve significantly better results even when the temperature was increased to 320 °C.

Example 2

Heavy atmospheric gas oil prepared by distillation of crude oil supplied by the Druzhba oil pipeline was hydrodesulfurized under a hydrogen pressure of 3.0 MPa in a flow reactor with a catalytic bed volume of 100 cm by the process according to the invention on a cobalt-molybdenum catalyst (D) prepared by -1 3 3 coextrusion. The volume velocity was 2.5 h and the hydrogen to raw material ratio was 350:1 m _n /m raw material. Before the experiment, the catalyst was sulfurized with a mixture of hydrogen and hydrogen sulfide with a content of 1% by volume HjS by gradually heating it in the stream of the above mixture to a temperature of 420 °C. After sulfurization, the temperature was reduced to 330 °C and gas oil injection was started. The gas mixture was replaced with technically pure hydrogen. The reaction temperature was gradually increased until a sulfur content in the exhaust of 0.1% by mass was reached.

For comparison, gas oil was desulfurized using the same procedure on a cobalt-molybdenum catalyst (E) prepared by co-precipation and also on a cobalt-molybdenum catalyst (F) prepared by successive carbonization of the carrier - active alumina with metal solutions with intermediate calcination after each carbonization.

Properties of atmospheric gas oil:

Density/20° dist. range % vol.

% vol.

i vol. sulfur content nitrogen content

865 kg/ ^m3

270 °C 327 °C 360 °C 1.07 wt% 250 ppm

Properties of catalysts:

bulk density f/1

MyOj

CoO

Na ₂ O

D E F

700 680 690

15.2 15.1 15.0

4.4 4.6 4.5

0.05 0.09 0.07

The catalysts were used for tests in a granular state (grain size 1 to 2 mm).

Gas oil desulfurization test results:

AND.

Catalyst D

The reaction temperature required to achieve 0.1 wt. %.

sulfur in exhaust °C 350

XI.

E

370

III.

F

355

The hydrodesulfurization process according to the invention allows a reduction in the reaction temperature by 20 to 5 °C compared to processes using catalysts prepared by co-precipation or carbonation.

Claims (2)

OBJECT OF THE INVENTION 1. A method for improving the quality of petroleum distillates, in particular gasoline, kerosene and diesel fuel, by hydrotreating sulfur and nitrogen compounds, unsaturated and aromatic hydrocarbons in the presence of an alumina-based extrudate catalyst containing metals VI and VIII, boiling up to 200 ° C or a kerosene fraction boiling in the range of 140 to 250 ° C or diesel fuel boiling in the range of 140 to 360 ° C is treated in a hydrogen gas stream at a pressure of 2.5 to 5.0 MPa and a throughput of 1.0 to 6, 0 h 1, characterized in that the heavy diesel fuel contains 5 to 15 wt. portions boiling in the range of 350 to 360 ° C are hydrotreated at a desulfurization degree above 85% and at 280 to 360 ° C on a cobalt-molybdenum-1 to 2 mm extrudate catalyst prepared by coextrusion with an aluminum hydrate of Boehmite or pseudoboehmite structure, having a pore volume of 0.35 to 0.70 cm @ 2 / g and CoMoO @ 2 crystal sizes below 50 S. 2. A process according to claim 1 wherein the catalyst is treated with a mixture of hydrogen and sulfane in moles before hydrotreating. a ratio of 80 to 600 with a gradual increase in temperature in the range of 20 to 400 ° C.