A method for preparing high-density fuel by modifying coal tar with diazomethane

Abstract

The application discloses a method for preparing high-density fuel by modifying coal tar with diazomethane, which comprises the following steps: distilling and separating coal tar to obtain a coal tar naphthalene oil fraction, adding a catalyst and a modifier into the coal tar naphthalene oil fraction in sequence to perform ring-increasing modification reaction and obtain a modified product, performing liquid separation and purification on the modified product, obtaining an aqueous phase and an organic phase by liquid separation, treating the aqueous phase to recover the catalyst, purifying the organic phase to obtain modified tar, and performing hydrogen treatment on the modified tar to synthesize high-density fuel; the coal tar naphthalene oil fraction has a distillation range of 210 DEG C to 230 DEG C; the modifier is diazomethane; the purification is performed by performing rotary evaporation on the organic phase; and the hydrogen treatment on the modified tar to synthesize high-density fuel specifically comprises: performing hydrofining on the modified tar to obtain hydrogenated modified tar, performing deep hydrogen saturation reaction on the hydrogenated modified tar to obtain a deep hydrogenation product, and feeding the deep hydrogenation product into a separator to separate the high-density fuel.

Description

Technical Field

[0001] This invention belongs to the field of coal tar technology, specifically relating to a method for modifying coal tar with diazomethane to prepare high-density fuel. Background Technology

[0002] Coal tar is a liquid byproduct of coal pyrolysis at high temperatures. It is a complex mixture primarily composed of hydrocarbons, including benzene, toluene, xylene, naphthalene, and benzo[a]pyrene. Due to its high energy density and low sulfur content, coal tar is widely used in the fuel and energy sectors. The process of preparing fuel from coal tar typically involves the separation, dehydrogenation, and upgrading of the coal tar. First, coal is pyrolyzed by heating, producing coal tar and coke. Then, different components in the coal tar are separated through distillation and separation processes. Finally, through a series of catalytic, hydrogenation, and reforming reactions, the low-carbon hydrocarbons in the coal tar are converted into high-carbon hydrocarbons to improve its energy density and combustion performance. Coal tar-based fuel production is a viable alternative energy option that can effectively utilize coal resources and reduce dependence on petroleum.

[0003] Currently, traditional high-density fuels have five- or six-membered ring structures, which have relatively low density and calorific value, making them unsuitable for current demands. Existing technologies for producing jet fuel from coal tar cannot achieve ring-growth reactions, thus failing to fully utilize the potential of coal tar to obtain fuels with higher density. To obtain higher-density fuels, it is necessary to artificially synthesize hydrocarbons with polycyclic structures. A remaining problem is that as the number of rings increases, the hydrogen content gradually decreases, leading to a reduction in gravimetric calorific value, which limits further increases in volumetric calorific value.

[0004] Cyclopropane structures store high strain energy, and synthesizing fuels containing this structure can compensate for the decrease in calorific value caused by reduced hydrogen content, thereby further increasing the volumetric calorific value of the fuel. Currently, there is no well-developed technology for cyclopropanization in the synthesis of high-density fuels from coal tar. Summary of the Invention

[0005] The purpose of this invention is to overcome the problem of lack of cyclopropanization in the synthesis of high-density fuels from coal tar. A method for preparing high-density fuels by modifying coal tar with diazonium methane is proposed. The method involves distilling coal tar to obtain naphthalene oil fraction, adding a catalyst and a modifier to the obtained solution in sequence to carry out the modification reaction, and then synthesizing high-density fuel by hydrogenation of the modified product.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] A method for preparing high-density fuel by modifying coal tar with diazonium methane includes the following steps:

[0008] Coal tar is distilled to obtain a coal tar naphthalene oil fraction. A catalyst and a modifier are added sequentially to the coal tar naphthalene oil fraction to carry out a ring-proliferation modification reaction to obtain a modified product. The modified product is separated and purified to obtain an aqueous phase and an organic phase. The aqueous phase is treated to recover the catalyst, and the organic phase is purified to obtain modified tar. The modified tar is then hydrogenated to synthesize high-density fuel.

[0009] The coal tar naphthalene oil fraction has a distillation range of 210℃ to 230℃; the modifier used is diazonium methane; the purification process involves rotary evaporation of the organic phase.

[0010] The specific process of synthesizing high-density fuel by hydrogenating modified tar is as follows: the modified tar is hydrogenated and refined to obtain hydrogenated modified tar, the hydrogenated modified tar is subjected to a deep hydrogenation saturation reaction to obtain a deep hydrogenation product, and the deep hydrogenation product is passed into a separator for separation to obtain high-density fuel.

[0011] Furthermore, the reaction solvent for the ring-enhancing modification reaction is 1,2-dichloromethane, and the reaction conditions are as follows: reaction temperature of 10℃~20℃, reaction time of 250 min under normal pressure, and Pd / C catalyst with a mass fraction of 5%.

[0012] Furthermore, the modified products include 1a,2,7,7a-tetrahydrocyclo[1,2-b]naphthalene, 4-methyl-1a,7b-dihydrocyclo[1,2-a]naphthalene, 5-methyl-1a,7b-dihydrocyclo[1,2-a]naphthalene, 4,7-dimethyl-1a,7b-dihydrocyclo[1,2-a]naphthalene, and 3,4-dimethyl-1a,7b-dihydrocyclo[1,2-a]naphthalene. Naphthalene, 5,6-dimethyl-1a,7b-dihydrocyclo[1,2-a]naphthalene, 3,7-dimethyl-1a,7b-dihydrocyclo[1,2-a]naphthalene, 3,4,6-trimethyl-1a,7b-dihydrocyclo[1,2-a]naphthalene, 6,6a-dihydro-1aH-cyclopropano[1,2-a]indene, and 1a,6b-dihydrocyclopropano[1,2-d]benzo[b]thiophene.

[0013] Furthermore, when the catalyst and modifier are added sequentially to the obtained coal tar naphthalene oil fraction, the mass ratio of the coal tar naphthalene oil fraction to the modifier is 1:2.2.

[0014] Furthermore, when the catalyst and modifier are added sequentially to the obtained coal tar naphthalene oil fraction, the mass ratio of the catalyst to the coal tar naphthalene oil fraction is 1:6.6.

[0015] Furthermore, the catalyst is recovered by treating the aqueous phase by centrifugation and washing with deionized water and ethanol, followed by vacuum drying.

[0016] Furthermore, the evaporation temperature of rotary evaporation is 45–60℃, the absolute pressure of rotary evaporation is 15–25 kPa, and the evaporation time of rotary evaporation is 6–8 h.

[0017] Furthermore, the specific reaction conditions for hydrorefining are as follows: reaction temperature of 360℃~380℃, pressure of 10~11MPa, hydrogen-to-oil volume ratio of 1000:1~1200:1, reaction time of 5~6h, and catalyst of Ni-Mo / γ-Al2O3.

[0018] Furthermore, the reaction conditions for deep hydrogenation saturation are as follows: reaction temperature of 240℃~300℃, pressure of 5~9MPa, hydrogen-to-oil volume ratio of 700:1~1200:1, reaction time of 6~8h, and catalyst of Pt-Pd / SiO2-Al2O3.

[0019] A high-density fuel is prepared by the method described above for modifying coal tar with diazonium methane. The high-density fuel has a density value greater than 1.050 g / mL and a calorific value greater than 41.56 MJ / kg.

[0020] Compared with the prior art, the present invention has the following beneficial technical effects:

[0021] This invention proposes a method for modifying coal tar to prepare high-density fuel using diazonium methane. By using diazonium methane as a modifier to cyclopropanize coal tar, a high-density fuel containing a cyclopropane structure is synthesized, which increases the fuel density and improves combustion performance and stability.

[0022] This invention proposes a method for modifying coal tar with diazonium methane to prepare high-density fuel. The method uses naphthalene oil fraction from medium- and low-temperature coal tar to produce high-density fuel, thus fully realizing the efficient utilization of coal tar resources.

[0023] The present invention proposes a method for modifying coal tar to prepare high-density fuel using diazonium methane. The modified tar is subjected to hydrogenation treatment by combining hydrogenation refining with deep hydrogenation saturation, so that the cyclic aromatics are fully saturated into cyclic alkanes.

[0024] The present invention proposes a method for preparing high-density fuel by modifying coal tar with diazonium methane. The synthesized high-density fuel has a density greater than 1.050 g / mL and a calorific value greater than 41.56 MJ / kg, with higher density and greater calorific value. Attached Figure Description

[0025] The accompanying drawings are provided to further understand the invention and constitute a part of this invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0026] Figure 1 This is a flowchart of a method for preparing high-density fuel by modifying coal tar with diazonium methane according to the present invention.

[0027] Figure 2 This is a schematic diagram of the modification process of a method for preparing high-density fuel by modifying coal tar with diazonium methane, as described in an embodiment of the present invention.

[0028] Figure 3 This is a schematic diagram of the refining and hydrogenation process in an embodiment of the present invention, which involves using diazonium methane to modify coal tar and prepare high-density fuel.

[0029] Figure 4 This is a schematic diagram of the deep hydrogenation process in an embodiment of the present invention, which describes a method for modifying coal tar with diazonium methane to prepare high-density fuel. Detailed Implementation

[0030] The embodiments of the present invention will be described in further detail below:

[0031] This invention proposes a method for synthesizing high-density fuel by cyclization modification of coal tar. The method involves distilling coal tar to obtain a naphthalene oil fraction, sequentially adding a catalyst and a modifier to the resulting solution to carry out a modification reaction, and then hydrogenating the modified product to synthesize high-density fuel. The specific details include the following:

[0032] See Figure 1 A method for preparing high-density fuel by modifying coal tar with diazonium methane is disclosed. First, coal tar is distilled using true boiling point distillation. The naphthalene oil fraction within the 210℃–230℃ distillation range is used as the modification feedstock. Then, a Pd / C catalyst and diazonium methane are added sequentially to achieve ring-enhancing modification of the naphthalene oil fraction. The modified product is separated, the aqueous phase is treated to recover the catalyst, and the organic phase is purified to obtain modified tar. The modified tar is then hydrotreated and deeply hydrogenated to saturate, and finally separated in a separator to obtain high-density fuel.

[0033] The modified coal tar naphthalene oil fraction was subjected to a ring-enhancing modification reaction to obtain modified tar. Specifically, the naphthalene oil fraction and 1,2-dichloromethane were placed in a batch reactor, and 5% Pd / C was added as a catalyst. Diazomethane was used as a modifier. The reaction temperature was 10℃~20℃, and the reaction was carried out at atmospheric pressure for 250 min. The reaction products were 1a,2,7,7a-tetrahydrocyclo[1,2-b]naphthalene, 4-methyl-1a,7b-dihydrocyclo[1,2-a]naphthalene, 5-methyl-1a,7b-dihydrocyclo[1,2-a]naphthalene, and 4,7... -Dimethyl-1a,7b-dihydrocyclo[1,2-a]naphthalene, 3,4-dimethyl-1a,7b-dihydrocyclo[1,2-a]naphthalene, 5,6-dimethyl-1a,7b-dihydrocyclo[1,2-a]naphthalene, 3,7-dimethyl-1a,7b-dihydrocyclo[1,2-a]naphthalene, 3,4,6-trimethyl-1a,7b-dihydrocyclo[1,2-a]naphthalene, 6,6a-dihydro-1aH-cyclopropano[1,2-a]indene, 1a,6b-dihydrocyclopropano[1,2-d]benzo[b]thiophene.

[0034] During the ring-enhancing modification process, the mass ratio of naphthalene oil fraction to modifier was adjusted to 1:2.2.

[0035] The ratio of the amount of Pd / C catalyst used to the mass ratio of naphthalene oil fraction during the ring-enhancing modification process was 1:6.6.

[0036] The modified product was separated into an aqueous phase, which was then centrifuged, washed with deionized water and ethanol, and then vacuum dried to recover the catalyst.

[0037] Modified tar was obtained by rotary evaporation of the modified organic phase at a temperature of 45–60 °C, an absolute pressure of 15–25 kPa, and an evaporation time of 6–8 h.

[0038] Modified tar was hydrorefined under the following conditions: reaction temperature 360℃~380℃, pressure 10~11MPa, hydrogen-to-oil volume ratio 1000:1~1200:1, reaction time 5~6h, and Ni-Mo / γ-Al2O3 catalyst.

[0039] The modified tar after hydrogenation was placed in a high-pressure reactor for deep hydrogenation saturation reaction to obtain high-density fuel. The reaction conditions were: reaction temperature 240℃~300℃, pressure 5~9MPa, hydrogen-to-oil volume ratio 700:1~1200:1, reaction time 6~8h, and catalyst was Pt-Pd / SiO2-Al2O3.

[0040] The deep hydrogenation products are fed into a separator to obtain high-density fuel, with the reaction temperature and pressure kept consistent with those in the deep hydrogenation section.

[0041] A high-density fuel is prepared by the method described above for modifying coal tar with diazonium methane. The high-density fuel has a density value greater than 1.050 g / mL and a calorific value greater than 41.56 MJ / kg.

[0042] The present invention will be further described in detail below with reference to embodiments:

[0043] Example 1

[0044] (1) Take an appropriate amount of medium- and low-temperature coal tar and distill it in a true boiling point distillation apparatus. Take the coal tar naphthalene oil fraction at 210℃~230℃ as the modified raw material. The specific properties of the medium- and low-temperature coal tar used are shown in Table 1.

[0045] Table 1 Properties of Low-Temperature Coal Tar in Raw Materials

[0046]

[0047]

[0048] (2) After the coal tar naphthalene oil fraction cooled to room temperature, 800 μL of the coal tar naphthalene oil fraction and 18 mL of 1,2-dichloromethane, 124 mg of 5% Pd / C catalyst, and 1.8 g of diazomethane as a modifier were added to a 50 mL batch reactor. The reaction temperature was controlled at 15 °C, and the reaction was carried out for 250 min under normal pressure. The reaction products were 1a,2,7,7a-tetrahydrocyclo[1,2-b]naphthalene, 4-methyl-1a,7b-dihydrocyclo[1,2-a]naphthalene, and 5-methyl-1a,7b-dihydrocyclo[1,2-a]naphthalene. Naphthalene, 4,7-dimethyl-1a,7b-dihydrocyclo[1,2-a]naphthalene, 3,4-dimethyl-1a,7b-dihydrocyclo[1,2-a]naphthalene, 5,6-dimethyl-1a,7b-dihydrocyclo[1,2-a]naphthalene, 3,7-dimethyl-1a,7b-dihydrocyclo[1,2-a]naphthalene, 3,4,6-trimethyl-1a,7b-dihydrocyclo[1,2-a]naphthalene, 6,6a-dihydro-1aH-cyclopropano[1,2-a]indene, 1a,6b-dihydrocyclopropano[1,2-d]benzo[b]thiophene. The modification process involves reactions such as... Figure 1 As shown.

[0049] (3) After the reaction is complete, the reaction system is separated into an organic phase and an aqueous phase. The aqueous phase is centrifuged for 10 min, then washed with 10 mL of deionized water and 10 mL of ethanol, and then placed in a vacuum drying oven and dried at -0.1 MPa for 2 h to recover the catalyst Pd / C.

[0050] (4) The organic phase was rotary evaporated at 45℃ and 15kPa for 6 hours to remove the solvent and obtain modified tar. The properties of the obtained modified tar are shown in Table 2.

[0051] Table 2 Properties of Modified Tar

[0052] <![CDATA[Kinematic viscosity (100°C) / mm 2 ·s -1 > 70.8 Total sulfur content / % 0.18 Moisture content / % 0.95 Alkane content / % 7.82 Aromatic content / % 74.83

[0053] (5) Modified tar is introduced into the reactor. Nitrogen gas is first introduced to purge the air from the reactor, followed by hydrogen gas at a pressure of 10 MPa. The tar passes through a refined catalyst bed (Ni-Mo / γ-Al2O3), the reaction temperature is increased to 360℃, the reaction pressure is 10 MPa, the hydrogen-to-oil ratio is controlled at 1000:1, and the reaction time is 5 hours. This hydrogenation refining reaction removes S from 1a,6b-dihydrocyclopropano[1,2-d]benzo[b]thiophene in the form of H2S gas, generating 6,6a-dihydro-1aH-cyclopropano[1,2-a]indene. The reaction process is as follows: Figure 2 As shown. The resulting product is passed through a heat exchanger, condensed, and then fed into a high-pressure reactor. After passing through a hydrogenated catalyst bed (Pt-Pd / SiO2-Al2O3), nitrogen is first introduced to purge air from the reactor, followed by hydrogen gas at a pressure of 7 MPa. The reaction temperature is 280°C, the hydrogen-to-oil volume ratio is controlled at 1000:1, and the reaction time is 6 hours for deep hydrogenation saturation. The hydrogenated product is then passed through a separator for gas-liquid separation. The reaction temperature is 280°C, and the pressure is 7 MPa. The hydrogen in the gas phase can be recycled, and the liquid phase is a high-density fuel solution. The reactions involved in the deep hydrogenation process are as follows: Figure 3 As shown. The obtained products are decahydrocyclopropano[1,2-b]naphthalene, 4-methyldecahydrocyclopropano[1,2-a]naphthalene, 5-methyldecahydrocyclopropano[1,2-a]naphthalene, 4,7-dimethyldecahydrocyclopropano[1,2-a]naphthalene, 3,4-dimethyldecahydrocyclopropano[1,2-a]naphthalene, 5,6-dimethyldecahydrocyclopropano[1,2-a]naphthalene, 3,7-dimethyldecahydrocyclopropano[1,2-a]naphthalene, 3,4,6-trimethyldecahydrocyclopropano[1,2-a]naphthalene, and 1b,2,3,4,5,5a,6,6a-octahydro-1aH-cyclopropano[1,2-a]indene. The specific properties of the obtained products are shown in Table 3.

[0054] Table 3 Product Properties

[0055] <![CDATA[Kinematic viscosity (-40°C) / mm 2 ·s -1 > <49.9 <![CDATA[Kinematic Viscosity (-20°C) / mm 2 ·s -1 > <22.3 <![CDATA[Kinematic viscosity (20℃) / mm 2 ·s -1 > <6.9 Flash point (closed cup) ℃ >55 Mass calorific value (MJ / kg) >41.56 Freezing point ℃ <-65 Aromatic (and olefin) content % 5

[0056] Example 2

[0057] (1) Take an appropriate amount of medium- and low-temperature coal tar and distill it in a true boiling point distillation apparatus. Take the coal tar naphthalene oil fraction at 210℃~230℃ as the modified raw material. The specific properties of the medium- and low-temperature coal tar used are shown in Table 1.

[0058] (2) After the coal tar naphthalene oil fraction cooled to room temperature, 800 μL of the coal tar naphthalene oil fraction and 18 mL of 1,2-dichloromethane, 124 mg of 5% Pd / C catalyst, and 1.8 g of diazomethane as a modifier were added to a 50 mL batch reactor. The reaction temperature was controlled at 15 °C, and the reaction was carried out for 250 min under normal pressure. The reaction products were 1a,2,7,7a-tetrahydrocyclo[1,2-b]naphthalene, 4-methyl-1a,7b-dihydrocyclo[1,2-a]naphthalene, and 5-methyl-1a,7b-dihydrocyclo[1,2-a]naphthalene. Naphthalene, 4,7-dimethyl-1a,7b-dihydrocyclo[1,2-a]naphthalene, 3,4-dimethyl-1a,7b-dihydrocyclo[1,2-a]naphthalene, 5,6-dimethyl-1a,7b-dihydrocyclo[1,2-a]naphthalene, 3,7-dimethyl-1a,7b-dihydrocyclo[1,2-a]naphthalene, 3,4,6-trimethyl-1a,7b-dihydrocyclo[1,2-a]naphthalene, 6,6a-dihydro-1aH-cyclopropano[1,2-a]indene, 1a,6b-dihydrocyclopropano[1,2-d]benzo[b]thiophene.

[0059] (3) After the reaction is complete, the reaction system is separated into an organic phase and an aqueous phase. The aqueous phase is centrifuged for 10 min, then washed with 10 mL of deionized water and 10 mL of ethanol, and then placed in a vacuum drying oven and dried at -0.1 MPa for 2 h to recover the catalyst Pd / C.

[0060] (4) The organic phase was rotary evaporated at 45℃ and 20kPa for 7 hours to remove the solvent and obtain modified tar. The properties of the obtained modified tar are shown in Table 4.

[0061] Table 4 Properties of Modified Tar

[0062] <![CDATA[Kinematic viscosity (100℃) / mm 2 ·s -1 > 71.3 Total sulfur content / % 0.16 Moisture content / % 0.90 Alkane content / % 8.55 Aromatic content / % 75.83

[0063] (5) The modified tar is introduced into the reactor. Nitrogen gas is first introduced to purge the air in the reactor, and then hydrogen gas at a pressure of 10.5 MPa is introduced. The catalyst is Ni-Mo / γ-Al2O3. The reaction temperature is increased to 360℃, the reaction pressure is 10.5 MPa, the hydrogen-to-oil ratio is controlled at 1100:1, and the reaction time is 5.5 h. The hydrogen refining reaction is carried out to remove S in 1a,6b-dihydrocyclopropano[1,2-d]benzo[b]thiophene in the form of H2S gas to generate 6,6a-dihydro-1aH-cyclopropano[1,2-a]indene. The resulting product is condensed in a heat exchanger and then fed into a high-pressure reactor. After hydrogenation and saturation of the catalyst bed (Pt-Pd / SiO2-Al2O3), nitrogen is first introduced to purge air from the reactor, followed by hydrogen gas at a pressure of 9 MPa. The reaction temperature is 280°C, the hydrogen-to-oil volume ratio is controlled at 1200:1, and the reaction time is 8 hours for deep hydrogenation saturation. The hydrogenated product is then passed through a separator for gas-liquid separation. The reaction temperature is 280°C, and the pressure is 9 MPa. The hydrogen in the gas phase can be recycled, while the liquid phase is a high-density fuel solution. The products obtained are decahydrocyclopropano[1,2-b]naphthalene, 4-methyldecahydrocyclopropano[1,2-a]naphthalene, 5-methyldecahydrocyclopropano[1,2-a]naphthalene, 4,7-dimethyldecahydrocyclopropano[1,2-a]naphthalene, 3,4-dimethyldecahydrocyclopropano[1,2-a]naphthalene, 5,6-dimethyldecahydrocyclopropano[1,2-a]naphthalene, 3,7-dimethyldecahydrocyclopropano[1,2-a]naphthalene, 3,4,6-trimethyldecahydrocyclopropano[1,2-a]naphthalene, and 1b,2,3,4,5,5a,6,6a-octahydro-1aH-cyclopropano[1,2-a]indene. The specific properties of the products are shown in Table 5.

[0064] Table 5 Product Properties

[0065] <![CDATA[Kinematic viscosity (-40℃) / mm 2 ·s -1 > <48.7 <![CDATA[Kinematic viscosity (-20℃) / mm 2 ·s -1 > <21.1 <![CDATA[Kinematic viscosity (20℃) / mm 2 ·s -1 > <6.1 Flash point (closed cup) ℃ >56 Mass calorific value (MJ / kg) >41.72 Freezing point ℃ <-66 Aromatic (and olefin) content % 4

[0066] Example 3

[0067] (1) Take an appropriate amount of medium- and low-temperature coal tar and distill it in a true boiling point distillation apparatus. Take the coal tar naphthalene oil fraction at 210℃~230℃ as the modified raw material. The specific properties of the medium- and low-temperature coal tar used are shown in Table 1.

[0068] (2) After the coal tar naphthalene oil fraction cooled to room temperature, 800 μL of the coal tar naphthalene oil fraction and 18 mL of 1,2-dichloromethane, 124 mg of 5% Pd / C catalyst, and 1.8 g of diazomethane as a modifier were added to a 50 mL batch reactor. The reaction temperature was controlled at 15 °C, and the reaction was carried out at atmospheric pressure for 250 min. The reaction products were 1a,2,7,7a-tetrahydrocyclo[1,2-b]naphthalene, 4-methyl-1a,7b-dihydrocyclo[1,2-a]naphthalene, and 5-methyl-1a,7b-dihydrocyclo[1,2-a]naphthalene. Naphthalene, 4,7-dimethyl-1a,7b-dihydrocyclo[1,2-a]naphthalene, 3,4-dimethyl-1a,7b-dihydrocyclo[1,2-a]naphthalene, 5,6-dimethyl-1a,7b-dihydrocyclo[1,2-a]naphthalene, 3,7-dimethyl-1a,7b-dihydrocyclo[1,2-a]naphthalene, 3,4,6-trimethyl-1a,7b-dihydrocyclo[1,2-a]naphthalene, 6,6a-dihydro-1aH-cyclopropano[1,2-a]indene, 1a,6b-dihydrocyclopropano[1,2-d]benzo[b]thiophene.

[0069] (3) After the reaction is complete, the reaction system is separated into an organic phase and an aqueous phase. The aqueous phase is centrifuged for 10 min, then washed with 10 mL of deionized water and 10 mL of ethanol, and then placed in a vacuum drying oven and dried at -0.1 MPa for 2 h to recover the catalyst Pd / C.

[0070] (4) The organic phase was rotary evaporated at 45℃ and 25kPa for 8 hours to remove the solvent and obtain modified tar. The properties of the obtained modified tar are shown in Table 6.

[0071] Table 6 Properties of Modified Tar

[0072] <![CDATA[Kinematic viscosity (100℃) / mm 2 ·s -1 > 71.8 Total sulfur content / % 0.13 Moisture content / % 0.70 Alkane content / % 9.31 Aromatic content / % 75.83

[0073] (5) The modified tar is introduced into the reactor. Nitrogen gas is first introduced to purge the air in the reactor, and then hydrogen gas at a pressure of 11 MPa is introduced. The catalyst is Ni-Mo / γ-Al2O3. The reaction temperature is increased to 360℃, the reaction pressure is 11 MPa, the hydrogen-to-oil ratio is controlled at 1200:1, and the reaction time is 6h. The hydrogenation refining reaction is carried out to remove S in 1a,6b-dihydrocyclopropano[1,2-d]benzo[b]thiophene in the form of H2S gas to generate 6,6a-dihydro-1aH-cyclopropano[1,2-a]indene. The resulting product is condensed in a heat exchanger and then fed into a high-pressure reactor. After hydrogenation and saturation of the catalyst bed (Pt-Pd / SiO2-Al2O3), nitrogen is first introduced to purge air from the reactor, followed by hydrogen gas at a pressure of 5 MPa. The reaction temperature is 280°C, the hydrogen-to-oil volume ratio is controlled at 700:1, and the reaction time is 7 hours for deep hydrogenation saturation. The hydrogenated product is then passed through a separator for gas-liquid separation. The reaction temperature is 280°C, and the pressure is 5 MPa. The hydrogen in the gas phase can be recycled, while the liquid phase is a high-density fuel solution. The products obtained are decahydrocyclopropano[1,2-b]naphthalene, 4-methyldecahydrocyclopropano[1,2-a]naphthalene, 5-methyldecahydrocyclopropano[1,2-a]naphthalene, 4,7-dimethyldecahydrocyclopropano[1,2-a]naphthalene, 3,4-dimethyldecahydrocyclopropano[1,2-a]naphthalene, 5,6-dimethyldecahydrocyclopropano[1,2-a]naphthalene, 3,7-dimethyldecahydrocyclopropano[1,2-a]naphthalene, 3,4,6-trimethyldecahydrocyclopropano[1,2-a]naphthalene, and 1b,2,3,4,5,5a,6,6a-octahydro-1aH-cyclopropano[1,2-a]indene. The specific properties of the products are shown in Table 7.

[0074] Table 7 Product Properties

[0075] <![CDATA[Kinematic Viscosity (-40°C) / mm 2 ·s -1 > <48.2 <![CDATA[Kinematic viscosity (-20°C) / mm 2 ·s -1 > <20.7 <![CDATA[Kinematic viscosity (20℃) / mm 2 ·s -1 > <5.7 Flash point (closed cup) ℃ >56 Mass calorific value (MJ / kg) >41.79 Freezing point ℃ <-66 Aromatic (and olefin) content % 4

[0076] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit its scope of protection. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that after reading the present invention, they can still make various changes, modifications or equivalent substitutions to the specific implementation of the invention, but these changes, modifications or equivalent substitutions are all within the scope of protection of the pending claims of the invention.

Claims

1. A method for preparing high-density fuel by modifying coal tar with diazonium methane, characterized in that, Includes the following steps: Coal tar is distilled to obtain a coal tar naphthalene oil fraction. A catalyst and a modifier are added sequentially to the coal tar naphthalene oil fraction to carry out a ring-proliferation modification reaction to obtain a modified product. The modified product is separated and purified to obtain an aqueous phase and an organic phase. The aqueous phase is treated to recover the catalyst, and the organic phase is purified to obtain modified tar. The modified tar is then hydrogenated to synthesize high-density fuel. The coal tar naphthalene oil fraction has a distillation range of 210℃ to 230℃; the modifier used is diazonium methane; the purification process involves rotary evaporation of the organic phase. The specific process of synthesizing high-density fuel by hydrogenating modified tar is as follows: the modified tar is hydrogenated and refined to obtain hydrogenated modified tar, the hydrogenated modified tar is subjected to a deep hydrogenation saturation reaction to obtain a deep hydrogenation product, and the deep hydrogenation product is passed into a separator for separation to obtain high-density fuel. The reaction solvent for the ring-enlargement modification reaction was 1,2-dichloromethane. The reaction conditions were: reaction temperature of 10℃~20℃, reaction time of 250 min under normal pressure, and Pd / C catalyst with a mass fraction of 5%. Modified products include 1a,2,7,7a-tetrahydrocyclo[1,2-b]naphthalene, 4-methyl-1a,7b-dihydrocyclo[1,2-a]naphthalene, 5-methyl-1a,7b-dihydrocyclo[1,2-a]naphthalene, 4,7-dimethyl-1a,7b-dihydrocyclo[1,2-a]naphthalene, 3,4-dimethyl-1a,7b-dihydrocyclo[1,2-a]naphthalene, 5 ,6-Dimethyl-1a,7b-dihydrocyclo[1,2-a]naphthalene, 3,7-dimethyl-1a,7b-dihydrocyclo[1,2-a]naphthalene, 3,4,6-trimethyl-1a,7b-dihydrocyclo[1,2-a]naphthalene, 6,6a-dihydro-1aH-cyclopropano[1,2-a]indene and 1a,6b-dihydrocyclopropano[1,2-d]benzo[b]thiophene; When the catalyst and modifier are added sequentially to the obtained coal tar naphthalene oil fraction, the mass ratio of the coal tar naphthalene oil fraction to the modifier is 1:2.2; the mass ratio of the catalyst to the coal tar naphthalene oil fraction is 1:6.

6. The specific steps for treating the aqueous phase to recover the catalyst are as follows: the aqueous phase is centrifuged and washed with deionized water and ethanol, and then vacuum dried to recover the catalyst. The evaporation temperature of rotary evaporation is 45~60℃, the absolute pressure of rotary evaporation is 15~25kPa, and the evaporation time of rotary evaporation is 6~8h; The specific reaction conditions for hydrorefining are as follows: reaction temperature is 360℃~380℃, pressure is 10~11MPa, hydrogen-oil volume ratio is 1000:1~1200:1, reaction time is 5~6h, and the catalyst is Ni-Mo / γ-Al2O3. The reaction conditions for deep hydrogenation saturation are: reaction temperature of 240℃~300℃, pressure of 5~9MPa, hydrogen-oil volume ratio of 700:1~1200:1, reaction time of 6~8h, and catalyst of Pt-Pd / SiO2-Al2O3. The high-density fuel produced has a density greater than 1.050 g / mL and a calorific value greater than 41.56 MJ / kg.

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