A method for producing polycyclic high-density fuels from a tetralindene process by-product

Abstract

The present invention relates to a process for the production of polycyclic high-density fuel from the by-products of tetrahydrodicyclopentadiene process. The process involves 1) recovering the by-product multimeric heavies from the production of tetrahydrodicyclopentadiene by Diels-Alder addition process using a wiped-plate rectifier to obtain C17-C22 components; 2) subjecting the C17-C22 components obtained in step 1 to hydroisomerization to obtain a polycyclic composition which can be used as a high-density fuel, as a space or aviation fuel or as a space or aviation fuel additive. The process recovers the excessive multimeric by-products that were previously discarded from the tetrahydrodicyclopentadiene production process.

Description

Technical Field

[0001] This invention belongs to the field of tetracyclododecene technology, specifically relating to a method for high-value utilization of tetracyclododecene process by-products. Background Technology

[0002] Multi-ring high-density fuels can improve the performance of aerospace vehicles (range, payload, speed). Compared with conventional fuels (such as aviation kerosene and rocket kerosene), they have advantages such as high density and high volumetric calorific value, and have a lower freezing point, making them suitable for a wide range of applications. Existing technologies have reported numerous applications of polycyclic high-density fuels. Patent CN116355646 discloses a method for preparing high-density fuels by hydrogenating polycyclic aromatic hydrocarbons; patent CN109852441 discloses high-density C19-C20 polycyclic alkane fuels prepared from biomass; patent CN104449818 discloses a mixture of tetrahydrodicyclopentadiene and tetrahydrotricyclopentadiene as a high-density fuel; patent CN116924883 discloses a method for obtaining high-density fuel by hydrogenating tetracyclododecene to obtain tetracyclododecane, mentioning the conversion of some bridged structures to hanging structures to lower the freezing point of the material and improve its low-temperature performance; similarly, CN105062579 discloses the conversion of some bridged tetrahydrodicyclopentadiene to hanging tetrahydrodicyclopentadiene to improve the low-temperature performance of the fuel.

[0003] Coated carbon (COC) is a high-performance thermoplastic engineering plastic, and tetracyclododecene is the monomer for synthesizing lens-grade COC. Tetracyclododecene (TCD) is synthesized using the traditional DA addition method, as described in patent JP1998287592A. This involves reacting dicyclopentadiene and norbornene at 190-200°C, followed by multi-step distillation to obtain the tetracyclododecene product, with a final yield of 78%. Because cyclopentadiene and the TCD product are relatively reactive at high temperatures, they further react with the generated TCD to produce hexacycloheptadecene and octacyclotidecene, while some TCD dimers, such as nonacyclotetracosane, are also formed. These substances are mostly of a bridged configuration, exhibit poor low-temperature fluidity, and have low freezing points. They are trapped within larger molecular weight polymers and are treated as waste liquid. Summary of the Invention

[0004] To address the aforementioned problems in existing technologies, the present invention aims to provide a method for preparing polycyclic high-density fuel using a byproduct of the tetracyclododecene process. The method involves using the heavy polymer byproducts from the traditional DA addition method for preparing tetracyclododecene, followed by scraped distillation to obtain C17-C22 fractions, which are then subjected to hydroisomerization to obtain a polycyclic composition containing 5-95% heptadecane, 5-95% octacyclododecene, and 5-95% nonacyclotetracosane. The composition has a density of 0.932-1.01 g / ml, a freezing point of -10 to -40°C, and a calorific value of 40-48 MJ / kg, thus avoiding the low-value utilization of the C19-C22 fraction in the tetracyclododecene preparation process. This results in a novel fuel with high density, high calorific value, and a low freezing point.

[0005] To achieve the above-mentioned objectives, the technical solution adopted by the present invention is as follows:

[0006] A method for preparing polycyclic high-density fuels using tetracyclododecene as a byproduct of a process includes the following steps:

[0007] 1) The by-product polymer heavy component generated during the preparation of tetracyclododecene by the DA addition method was obtained by scraped distillation to obtain the C17-C22 component;

[0008] 2) The C17-C22 components obtained in step 1 were subjected to hydrogenation isomerization to obtain a polycyclic composition.

[0009] In one specific implementation, the polymeric heavy component in step 1) is a heavy component waste liquid obtained by distillation after dicyclopentadiene and norbornene undergo a DA addition reaction at 170℃-250℃ to remove tetracyclododecene.

[0010] The polymeric heavy components are mainly composed of A) hexacycloheptadecene, B) octacyclotidodecene, and C) nonacyclotidodecane, wherein the content of the main component is greater than 50%, or greater than 70%, or greater than 90%.

[0011]

[0012] In one specific implementation, the scraped distillation in step 1) uses a distillation apparatus with 10-35 trays; a vacuum degree of 0.15-0.45 kPa; a reflux ratio of 3-10:1; and a fraction with a top temperature of 135-190℃.

[0013] In one specific implementation, the C17-C22 components in step 1) comprise 2.5wt%-95wt% hexacycloheptadecene, 2.5wt%-95wt% octacyclotidodecene, and 2.5wt%-95wt% nonacyclotetracosane.

[0014] In one specific embodiment, the hydroisomerization in step 2) is carried out in the presence of a hydroisomerization catalyst, which comprises an active metal and a catalyst support. The active metal is selected from one or more combinations of Ni, Ru, Pt, and Pd, preferably Ni. The content of the active metal is 0.5wt%-5wt%, preferably 1.5wt%-3.5wt%. The catalyst support is selected from cobalt oxide or a mixture of cobalt trioxide, alumina, and silicon oxide, wherein the Si / Al mass ratio is 3-8, preferably 3.5-6, and the Co / Al mass ratio is 0.1-0.5, preferably 0.2-0.4.

[0015] In one specific embodiment, the method for preparing the hydroisomerization catalyst includes the following steps:

[0016] 1) A certain proportion of hydrated alumina, silica sol, cobalt nitrate, sodium hydroxide, diethylamine, and deionized water are added to a hydrothermal reactor for high-temperature hydrothermal treatment. Preferably, the hydrothermal temperature is 150-210℃, more preferably 160-190℃, the hydrothermal time is 4-12h, more preferably 6-9h, the sodium hydroxide concentration is 0.1-1%, more preferably 0.2-0.5%, and the diethylamine concentration is 2%-15%, more preferably 2%-8%. The solid obtained after filtration is then washed with deionized water.

[0017] 2) The above solid is calcined at high temperature in air atmosphere, preferably at a calcination temperature of 300-550℃, more preferably at 400-500℃, and for a calcination time of 2-8h, more preferably 4-6h;

[0018] 3) Add the calcined solid to an aqueous solution, and impregnate it with Ni, Ru, Pt, and Pd metal salts respectively. After filtration and calcination, a catalyst is obtained. Preferably, the impregnation temperature is 25-85℃, more preferably 40-60℃, the impregnation time is 4-12h, 6-10h, the calcination temperature is preferably 300-550℃, more preferably 400-500℃, and the calcination time is 1-6h, more preferably 2-4h.

[0019] In one specific implementation, the hydroisomerization reaction in step 2) is carried out in a fixed bed at a reaction temperature of 135-200°C, preferably 140-180°C, and a space velocity of 1-10 h⁻¹. -1 3-5 hours is preferred -1 The reaction pressure is 0.5-7 MPa, preferably 1-4 MPa; the hydrogen-to-oil ratio is 100-600, preferably 200-400.

[0020] In one specific implementation, the hydroisomerized product described in step 2) comprises S1: 2.5-95 wt% of hexacycloheptadecane, S2: 2.5-95 wt% of octacyclododecane, and S3: 2.5-95 wt% of nonacyclotetradecane, with a total proportion of 98-100%.

[0021]

[0022] In one specific implementation, the hydroisomerized product described in step 2) further includes the following three non-hydrogenated components: F1, F2, and C, with a total mass content ≤ 2%.

[0023]

[0024] In one specific implementation, the hydroisomerized product described in step 2) further includes unhydrogenated components A and B, with a total mass content ≤1%.

[0025] In one specific implementation, the hydrogenated isomer product described in step 2) has a density of 0.932-1.01 g / ml, a freezing point of -10 to -40°C, and a calorific value of 40-48 MJ / Kg.

[0026] The positive effects of this invention are as follows:

[0027] The purpose of this invention is to provide a method for preparing polycyclic high-density fuels using tetracyclododecene as a byproduct of the process. The method utilizes the advantages of scraped distillation to separate high-viscosity, high-boiling-point substances byproducts of tetracyclododecene prepared by the traditional DA addition method, and successfully obtains C17-C22 components by controlling the collection conditions of the distillate.

[0028] By selecting a catalyst support consisting of cobalt oxide, cobalt trioxide, and a mixture of alumina and silica, and leveraging the multivalent state changes of cobalt and the acidity of the support, polycyclic C17 and C22 olefin fractions are hydrogenated and isomerized into high-hanging C17 and C22 polycyclic alkanes. Due to the high proportion of hanging alkanes, the prepared polycyclic alkanes still exhibit better low-temperature performance. Simultaneously, the process offers advantages such as good reaction selectivity and high yield, facilitating industrial production. The resulting novel high-density fuel achieves the same level of calorific value, density, and low-temperature performance as other similar products, and possesses a price advantage due to the use of raw materials derived from other industrial wastewater. Detailed Implementation

[0029] The technical solution of the present invention will be further described below through examples, but it is not limited thereto.

[0030] Unless otherwise specified, all raw materials used in this invention are commercially available; and unless otherwise specified, all equipment is conventionally used in the field.

[0031] The gas chromatography analysis method used in this invention was as follows: a Shimadzu Anglilent 7820A gas chromatograph, a DB-5 capillary column (5% Phenoyl Methyl Siloxan, 30m × 0.32mm × 0.25μm), and a flame ionization detector (FID). The injector and detector temperatures were both 290℃; the column temperature was initially set at 100℃ and held for 1 minute, then increased to 250℃ at a rate of 15℃ / min and held for 5 minutes. The column pressure was 8.59 ps i, and the flow rate was 1.5 mL / min. The injection volume was 0.2 μL. Conversion and selectivity were calculated using the area normalization method.

[0032] In this invention, the preparation method of the hydrogenation catalyst in the embodiments is as follows:

[0033] Add 500g of deionized water to a hydrothermal reactor, along with a certain amount of alumina, silica sol, cobalt nitrate, 0.3% sodium hydroxide, and 5% diethylamine. The mixture is then hydrothermally treated at 170℃ for 8 hours. The resulting solid is then filtered and washed with deionized water. The solid is calcined at 450℃ for 5 hours in air. The calcined solid is then added to an aqueous solution, and a metal salt is added for impregnation at 50℃ for 8 hours. After filtration and washing, the solid is calcined again at 450℃ for 5 hours in air to obtain the catalyst. The raw materials and dosages used in each embodiment are shown in the table below.

[0034]

[0035]

[0036] Example 1

[0037] The polymeric heavy components (60% hexacyclic heptadecene, 30% octacyclic dodecene, and 10% nonacyclic tetradecane) produced by the addition process of 1 kg DA were separated by distillation in a scraped plate distillation unit with 15 trays. The top vacuum was 0.35 kPa, the reflux ratio was 5:1, and the fraction with a top temperature of 135-190 °C was collected. This collected fraction was introduced into a fixed-bed hydrogenation reactor, using a mixed oxide support of 2.5 wt% Ni / cobalt oxide, alumina, and silica as the catalyst (Si / Al ratio 4.5, Co / Al ratio 0.2). The reaction temperature was 170 °C, and the space velocity was 4 h⁻¹. -1 The reaction pressure was 3 MPa, and the hydrogen-to-oil ratio was 300. Gas phase analysis of the collected product showed that it contained 98.0% of heptadecane, octacyclododecane, and nonacyclotetradecane. The total content of F1, F2, and C (three non-hydrogenated isomers) was 1.5%. The total content of unhydrogenated olefin impurities was 0.5%. The product density was 1.00 g / ml, freezing point -40℃, and calorific value (determined according to the national standard GB384-81 "Determination of Calorific Value of Petroleum Products") was 48 MJ / kg.

[0038] Example 2

[0039] In a scraped-plate distillation unit with 10 trays, the byproducts (60% hexacyclic heptadecene, 30% octacyclic dodecene, and 10% nonacyclic tetradecane) from the preparation of tetracyclododecene via the DA addition method were separated by distillation. The column was kept under a vacuum of 0.45 kPa and a reflux ratio of 10:1. The fraction with a top temperature between 135 and 190 °C was collected. This collected fraction was introduced into a fixed-bed hydrogenation reactor, using a mixed oxide support of 1.5 wt% Ru / cobalt oxide, alumina, and silica as the catalyst (Si / Al ratio 3.5, Co / Al ratio 0.4). The reaction temperature was 180 °C, and the space velocity was 5 h⁻¹. -1 The reaction pressure was 0.5 MPa, and the hydrogen-to-oil ratio was 600. Gas phase analysis of the collected product showed that it contained 99.9% of heptadecane, octacyclododecane, and nonacyclotetradecane. The total content of non-hydrogenated impurities F1, F2, and C was 0.1%. The total content of non-hydrogenated olefin impurities was 0%. The product density was 0.932 g / ml, freezing point -30℃, and calorific value (determined according to the national standard GB384-81 "Determination of Calorific Value of Petroleum Products") was 42 MJ / kg.

[0040] Example 3

[0041] In a 20-plate scraped distillation unit, the byproducts (60% hexacyclic heptadecene, 30% octacyclic dodecene, and 10% nonacyclic tetracosane) from the preparation of tetracyclododecene via the DA addition method were separated by distillation. The column was kept under a vacuum of 0.4 kPa and a reflux ratio of 3:1, collecting fractions with top temperatures between 135 and 190 °C. This collected fraction was introduced into a fixed-bed hydrogenation reactor, using a mixed oxide support of 3.5 wt% Pt / cobalt oxide, alumina, and silica as the catalyst (Si / Al ratio 6, Co / Al ratio 0.3). The reaction temperature was 140 °C; the space velocity was 3 h⁻¹; the reaction pressure was 1 MPa; and the hydrogen-to-oil ratio was 400. Gas phase analysis of the collected product showed that the product contained 98.0% of the suspended hexacyclic heptadecene, suspended octacyclic dodecene, and suspended nonacyclic tetracosane. The total content of F1, F2, and C (three non-isomerized impurities from hydrogenation) was 1%. Unhydrogenated olefin impurities, total content 1%. Tests showed product density 1.01 g / ml, freezing point -10℃, calorific value (determined according to national standard GB384-81 "Determination of Calorific Value of Petroleum Products") 46 MJ / Kg.

[0042] Example 4

[0043] In a 25-plate scraped distillation unit, the byproducts (60% hexacyclic heptadecene, 30% octacyclic dodecene, and 10% nonacyclic tetracosane) from the preparation of tetracyclododecene via the DA addition method were separated by distillation. The column was kept under a vacuum of 0.3 kPa and a reflux ratio of 7, collecting fractions with top temperatures between 135 and 190 °C. This collected fraction was introduced into a fixed-bed hydrogenation reactor, using a mixed oxide support of 0.5% Pd / cobalt oxide, alumina, and silica as the catalyst (Si / Al ratio 9, Co / Al ratio 0.5). The reaction temperature was 120 °C; the space velocity was 10 h⁻¹; the reaction pressure was 4 MPa; and the hydrogen-to-oil ratio was 100. Gas phase analysis of the collected product showed that the product contained 98% of the suspended hexacyclic heptadecene, suspended octacyclic dodecene, and suspended nonacyclic tetracosane. The total content of the three non-isomerized impurities F1, F2, and C was 1.3%. Unhydrogenated olefin impurities, total content 0.7%. Tests showed product density 1.00 g / ml, freezing point -20℃, calorific value (determined according to national standard GB384-81 "Determination of Calorific Value of Petroleum Products") 41 MJ / Kg.

[0044] Example 5

[0045] In a 35-plate scraped distillation unit, the byproducts (60% hexacyclic heptadecene, 30% octacyclic dodecene, and 10% nonacyclic tetracosane) from the preparation of tetracyclododecene via the DA addition method were separated by distillation. The column was kept under a vacuum of 0.15 kPa and a reflux ratio of 8:1, collecting fractions with top temperatures between 135 and 190 °C. This collected fraction was introduced into a fixed-bed hydrotreating reactor, using a mixed oxide support of 5% Ni / cobalt oxide, alumina, and silica as the catalyst (Si / Al ratio 3, Co / Al ratio 0.1). The reaction temperature was 135 °C; the space velocity was 1 h⁻¹; the reaction pressure was 7 MPa; and the hydrogen-to-oil ratio was 200. Gas phase analysis of the collected product showed that the product contained 98.5% of the suspended hexacyclic heptadecene, suspended octacyclic dodecene, and suspended nonacyclic tetracosane. The total content of F1, F2, and C (three non-isomerized impurities from hydrotreating) was 1.1%. Unhydrogenated olefin impurities, total content 0.4%. Tests showed product density 0.95 g / ml, freezing point -30℃, calorific value (determined according to national standard GB384-81 "Determination of Calorific Value of Petroleum Products") 40 MJ / Kg.

[0046] Comparative Example 1

[0047] Except for the use of Raney nickel catalyst, all other conditions were the same as in Example 1. Results showed that the product contained 90% of the total content of heptadecane, octacyclododecane, and nonacyclotetradecane. The total content of F1, F2, and C (three non-hydrogenated isomers) was 9.5%. The total content of unhydrogenated olefin impurities was 0.5%. Tests revealed a product density of 0.925 g / ml, a freezing point of -12°C, and a calorific value (determined according to the national standard GB384-81 "Determination of Calorific Value of Petroleum Products") of 30 MJ / kg.

[0048] Comparative Example 2

[0049] Except for the catalyst, which uses 5% Pt / C, the other conditions were the same as in Example 1. The results showed that the product contained 81% of the total content of heptadecane, octacyclododecane, and nonacyclotetradecane. The total content of the three non-hydrogenated impurities, F1, F2, and C, was 17%. The total content of non-hydrogenated olefin impurities was 2%. Tests revealed that the product density was 0.932 g / ml, the freezing point was -10℃, and the calorific value (determined according to the national standard GB384-81 "Determination of Calorific Value of Petroleum Products") was 20 MJ / Kg.

Claims

1. A method for preparing polycyclic high-density fuels using tetracyclododecene as a byproduct of a process, comprising the following steps: 1) The by-product polymer heavy component generated during the preparation of tetracyclododecene by the DA addition method was obtained by scraped distillation to obtain the C17-C22 component; 2) The C17-C22 components obtained in step 1 were subjected to hydrogenation isomerization to obtain a polycyclic composition.

2. The method as described in claim 1, characterized in that, The polymer's main components are A) hexacyclic heptadecene, B) octacyclic dodecene, and C) nonacyclic tetradecane.

3. The method as described in claim 1 or 2, characterized in that, The C17-C22 composition in step 1) comprises 2.5wt%-95wt% hexacycloheptadecene, 2.5wt%-95wt% octacyclotidodecene, and 2.5wt%-95wt% nonacyclotetracosane.

4. The method according to any one of claims 1-3, characterized in that, Step 2) The hydroisomerization is carried out in the presence of a hydroisomerization catalyst, which comprises an active metal and a catalyst support. The active metal is selected from one or more combinations of Ni, Ru, Pt, and Pd, preferably Ni. The catalyst support is selected from cobalt oxide or a mixture of cobalt trioxide, aluminum oxide, and silicon oxide.

5. The method as described in claim 4, characterized in that, The active metal content is 0.5wt%-5wt%, preferably 1.5wt%-3.5wt%; and / or, the Si / Al mass ratio in the catalyst support is 3-8, preferably 3.5-6, and the Co / Al mass ratio is 0.1-0.5, preferably 0.2-0.

4.

6. The method as described in claim 4 or 5, characterized in that, The preparation method of the hydroisomerization catalyst includes the following steps: 1) A certain proportion of hydrated alumina, silica sol, cobalt nitrate, sodium hydroxide, diethylamine, and deionized water are added to a hydrothermal reactor for high-temperature hydrothermal treatment. Preferably, the hydrothermal temperature is 150-210℃, more preferably 160-190℃, the hydrothermal time is 4-12h, more preferably 6-9h, the sodium hydroxide concentration is 0.1-1%, more preferably 0.2-0.5%, and the diethylamine concentration is 2%-15%, more preferably 2%-8%. The solid obtained after filtration is then washed with deionized water. 2) The above solid is calcined at high temperature in air atmosphere, preferably at a calcination temperature of 300-550℃, more preferably at 400-500℃, and for a calcination time of 2-8h, more preferably 4-6h; 3) Add the calcined solid to an aqueous solution, and impregnate it with Ni, Ru, Pt, and Pd metal salts respectively. After filtration and calcination, a catalyst is obtained. Preferably, the impregnation temperature is 25-85℃, more preferably 40-60℃, the impregnation time is 4-12h, 6-10h, the calcination temperature is preferably 300-550℃, more preferably 400-500℃, and the calcination time is 1-6h, more preferably 2-4h.

7. The method according to any one of claims 1-6, characterized in that, The hydroisomerization reaction described in step 2) is carried out in a fixed bed at a temperature of 135-200°C, preferably 140-180°C, and a space velocity of 1-10 h⁻¹. -1 3-5 hours is preferred -1 The reaction pressure is 0.5-7 MPa, preferably 1-4 MPa; the hydrogen-to-oil ratio is 100-600, preferably 200-400.

8. The hydroisomerized product prepared by the method according to any one of claims 1-7, characterized in that, The hydroisomerized product contains S1: 2.5-95wt% of hexacyclic heptadecane, S2: 2.5-95wt% of octacyclic dodecane, and S3: 2.5-95wt% of nonacyclic dodecane, with the total proportion of the three being 98-100%.

9. The hydroisomerized product as described in claim 8, characterized in that, The hydrogenated isomer product described in step 2) has a density of 0.932-1.01 g / ml, a freezing point of -10 to -40℃, and a calorific value of 40-48 MJ / Kg.

Images