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Jan 8, 2017 - ABSTRACT: 1-(3-Cyclopentyl)cyclopentyl-2-cyclopentylcy- clopentane, a renewable high-density fuel, was first produced in a high overall ...
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Synthesis of Renewable High-Density Fuel with Cyclopentanone Derived from Hemicellulose Wei Wang, Ning Li, Guangyi Li, Shanshan Li, Wentao Wang, Aiqin Wang, Yu Cong, Xiaodong Wang, and Tao Zhang ACS Sustainable Chem. Eng., Just Accepted Manuscript • DOI: 10.1021/ acssuschemeng.6b02554 • Publication Date (Web): 08 Jan 2017 Downloaded from http://pubs.acs.org on January 17, 2017

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Synthesis of Renewable High-Density Fuel with Cyclopentanone Derived from Hemicellulose Wei Wang†,‡, Ning Li*,†,§, Guangyi Li†,§, Shanshan Li†, Wentao Wang†, Aiqin Wang†,§, Yu Cong†, Xiaodong Wang†, Tao Zhang*,†,§ †State

Key Laboratory of Catalysis, Dalian Institute of Chemical Physics, Chinese Academy of

Sciences, No. 457 Zhongshan Road, Dalian 116023, China. ‡

Shaanxi Key Laboratory of Catalysis, School of Chemistry and Environment Science, Shaanxi

Sci-tech University, No. 1 Dongyihuan Road, Hanzhong, 723001, China. §iChEM (Collaborative Innovation Centre of Chemistry for Energy Materials), Dalian Institute of Chemical Physics, Chinese Academy of Sciences, No. 457 Zhongshan Road, Dalian 116023, China. E-mail addresses of the corresponding authors: [email protected]

(T. Zhang);

[email protected] (N. Li).

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ABSTRACT: 1-(3-Cyclopentyl)cyclopentyl-2-cyclopentylcyclopentane, a renewable highdensity fuel, was first produced in a high overall carbon yield (~70%) with cyclopenanone which can be derived from hemicellulose. The synthetic route used this work contains three steps. In the first step, 2-cyclopentyl cyclopentanone was synthesized for the first time by a one-pot reaction of cyclopentanone and hydrogen under the catalysis of Raney metal and alkali hydroxides. Over the optimized catalyst (Raney cobalt + KOH), a high carbon yield (83.3%) of 2-cyclopentyl cyclopentanone

was

achieved

at

353

K.

In

the

second step,

2-cyclopentyl-5-(2-

cyclopentylcyclopentylidene)cyclopentanone was produced in a high carbon yield (95.4%) by the solvent-free self-aldol condensation of 2-cyclopentyl cyclopentanone under the vacuum conditions. In the third step, the 2-cyclopentyl-5-(2-cyclopentylcyclopentylidene)cyclopentanone was hydrodeoxygenated over the Ni-SiO2 catalyst under solvent-free conditions. High carbon yields of 1-(3-cyclopentyl)cyclopentyl-2-cyclopentylcyclopentane (88.5%) and polycycloalkanes (99.0%) were obtained. The Ni-SiO2 catalyst was stable under investigated conditions. No evident deactivation was noticed during the 50 h time on stream. The polycycloalkane mixture as obtained has a density of 0.943 g mL-1 and a freezing point of 233.7 K. As a potential application, it can be blended into conventional high density fuels (e.g. JP-10) for rockets and missile propulsion.

KEYWORDS: High density fuel; Lignocellulose; Cyclopentanone; Aldol condensation; Selective hydrogenation; Hydrodeoxygenation.

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INTRODUCTION In recent years, the conversion of abundant and renewable biomass to high quality fuels1-3 and useful chemicals4-8 has drawn a lot of attention. Polycycloalkanes are a family of high density fuels which are widely used for special aviation and propulsion. Due to their special chemical structures, polycycloalkanes have relatively higher densities (or volumetric heat values) than traditional refined fuels9. In real application, polycycloalkanes can be used to increase the range, payload and/or velocity of aircrafts without increasing the volume of oil tank. Alternatively, they can also be used to decrease the size of fuel tank without impairing the flight performance. This character is especially useful for some volume-constrained aircrafts (such as rocket and missile) to save more space for ordinance, electronics, and other components. The currently used high density fuels (for example JP-10, RJ-4, RJ-5, etc.) are derived from fossil energy by the Diels-Alder reactions of cyclopentadiene (or methyl-cyclopentadiene) followed by isomerization and hydrogenation9. Because the fossil energy is limited and unrenewable, it is necessary to exploit some new synthetic routes for the preparation of high density fuel with renewable biomass. In the previous work of the Harvey10-12, Zou et al.13 and their co-workers, several synthetic routes for the renewable high density fuels have been developed using terpenes (such as pinene, limonene, camphene and crude turpentine, etc.), cineoles and linalool as the feedstocks. As we know, the terpenes, cineoles and linalool are usually obtained from some specific woods and plants. Their resources are limited. To fulfil the great demand of future application, some new synthetic routes for the production of high density fuels with cheaper and ampler biomass feedstocks should be exploited. Lignocellulose is the chief constitute of forestry and agricultural residues. It is much cheaper and more abundant than other forms of biomass. In recent years, plenty of work has been carried out on the synthesis of renewable fuels with the platform compounds which can be obtained from

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lignocellulose14-19. However, the reports about the production of high density fuel using lignocellulosic platform compounds are relatively fewer. Cyclopentanone is a lignocellulosic platform compound which can be obtained by the hydrogenation of furfural20. On the basis of its cyclic chemical structure, this compound can be utilized for the production of renewable high density fuel. In this work, 1-(3-cyclopentyl)cyclopentyl-2-cyclopentylcyclopentane, a C20 polycycloalkane with a density of 0.943 g mL-1 and a freezing point of 233.7 K, was first obtained in an overall carbon yield of ~70% with cyclopentanone and hydrogen. To the best of our knowledge, this density is the highest among those of reported lignocellusic hydrocarbon biofuels. As a potential application, this polycycloalkane can be used as an alternative fuel for rockets and missile propulsion. EXPERIMENTAL SECTION Catalyst Preparation. The KOH, NaOH, LiOH were supplied by Aladdin Chemical Reagent Co., Ltd. Raney Co, Raney nickel, Raney copper, and Raney iron were purchased from Dalian Tongyong

Chemical

Co.,

Ltd.

The

Ni-SiO2

catalyst

utilized

in

the

solvent-free

hydrodeoxygenation (HDO) step was prepared in accordance with literature21 by the depositionprecipitation (DP) method. Typically, 250 mL Ni(NO3)2⋅6H2O (10.2 g) aqueous solution was divided into two parts. 6.3 g urea was added to one part (50 mL), then the urea solution was added dropwise to the rest Ni(NO3)2⋅6H2O solution (200 mL) together with 1.9 g SiO2 and 0.3 mL HNO3 (65wt.%) under vigorous stirring at 353 K. After the precipitation process, the resulting suspension was rapidly heated to 363 K and stirred at that temperature for 10 h. Then the solid was filtered, washed to neutral, desiccated at 383 K for 10 h, and heated in air flow at 773 K for 4 h. Activity Test. Synthesis of 2-Cyclopentyl Cyclopentanone. The direct synthesis of 2cyclopentyl cyclopentanone by the one-pot reaction of cyclopentanone and hydrogen was

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conducted with a stainless steel batch reactor. For each test, 2.0 g cyclopentanone, 2.0 mL alkali hydroxide solution (1.25 mol L-1), 0.1 g Raney metal were utilized. Before the test, the stainless steel batch reactor was purged by argon for three times. The mixture of catalyst and reactant was stirred at 353 K for 6 h (According to the blank experiment result which was illustrated in Figure S1, the carbon yield of cyclopentylidene cyclopentanone over KOH at 353 K increased with reaction time, reached the maximum after 6 h and stabilized. Therefore, we chose 6 h as the reaction time for the first stage of the one-pot reaction). At this moment, hydrogen was introduced into the reactor until the system pressure reached 2.0 MPa. The reaction was conducted at 353 K for additional 2 h. Subsequently, the stainless steel batch reactor was quenched with ice. The liquid products were collected from the stainless steel batch reactor, extracted using ethyl acetate and analyzed by an Agilent 7890A gas chromatograph (GC) which equipped with a HP-INNOWAX capillary column (30 m, 0.25 mm ID, 0.5 mm film) and a flame ionization detector (FID). The oven temperature was held at 313 K for 2 min, increased to 553 K at a rate of 15 K min-1, and stayed at that temperature for 5 min. Helium was used as the carrier gas at a flow rate of 1.5 mL min−1. Synthesis of 2-cyclopentyl-5-(2-cyclopentylcyclopentylidene)cyclopentanone. The self-aldol condensation

of

2-cyclopentyl

cyclopentanone

to

2-cyclopentyl-5-(2-

cyclopentylcyclopentylidene)cyclopentanone was conducted in a flask which was connected with a condenser and a water pump to remove the water generated during the reaction (see Figure 1). Typically, 5.0 g 2-cyclopentyl cyclopentanone and 0.25 g alkali hydroxide were vigorously stirred at 423 K and ~3 kPa for 1 h. The liquid product was collected from the flask, diluted and analyzed by the same Agilent 7890A GC. According to the supporting information, the self-aldol condensation reactions of cyclopentanone and 2-cyclopentyl cyclopentanone under the catalysis of alkali hydroxide solution and alkali hydroxides follow heterogeneously-catalyzed pathways.

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Figure

1.

Reactor

for

the

synthesis

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of

2-cyclopentyl-5-(2-

the

2-cyclopentyl-5-(2-

cyclopentylcyclopentylidene)cyclopentanone. Hydrodeoxygenation

(HDO).

The

HDO

of

cyclopentylcyclopentylidene)cyclopentanone was conducted at 533 K under solvent-free conditions. 1.8 g of Ni-SiO2 catalyst was used. Before the test, the catalyst was in-situ pretreated at 733 K in a stainless steel tubular reactor by H2 flow (120 mL min-1) for 2 h. After the reactor temperature decreased to 533 K and stabilized at that value for 0.5 h. The 2-cyclopentyl-5-(2cyclopentylcyclopentylidene)cyclopentanone (purified by vacuum distillation) was fed into the reactor (0.04 mL min-1) along with H2 (120 mL min-1). After passing through a gas-liquid separator and a back pressure regulator (which was used to maintain the system pressure at 6 MPa), the gas phase products were analyzed online by an Agilent 6890N GC. The CO2 in the gaseous product was separated by a RESTEK HS-DB 100/120 packed column (30 feet, 1/8 inch outer diameter, 2.0 mm inner diameter) using helium as the carrier gas (flow rate: 24 mL min−1) and analyzed by a Thermal Conductivity Detector (TCD). The TCD and the injection port were held at 523 K and 393 K, respectively. The alkanes in the gaseous product were analyzed by a FID which was connected with a RESTEK Rt-Q-BOND capillary column (30 m, 0.32 mm ID, 10 μm film) using helium as the carrier gas (flow rate of 1 mL min−1). The oven temperature was held at 323 K for 2 min, then increased to 473 K at a rate of 15 K min-1 and kept at that

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temperature for 10 min. The liquid phase products were collected periodically from the bottom of separator, diluted and analyzed by the Agilent 7890A GC which was used for the analysis of condensation products. Results and Disscussion Synthesis of 2-Cyclopentyl cyclopentanone. 2-Cyclopentyl cylopentanone has a jasmine like smell and can be used as perfume, flavouring or wood preservative22. In the first part of this work, we explored the direct synthesis of 2-cyclopentyl cylopentanone by the one-pot reaction of cylopentanone and hydrogen under the catalysis of different Raney metals and alkali hydroxides. On the basis of GC analysis and NMR spectra (see Figures S2-S4), 2-cyclopentyl cylopentanone, 2-cyclopentylidene cyclopentanone and small amount of cyclopentanol were identified in the liquid products. According to Scheme 1, the 2-cyclopentylidene cyclopentanone was generated from the self-aldol condensation of cylopentanone. Cyclopentyl cylopentanone was produced by the selective hydrogenation of C=C bond in 2-cyclopentylidene cyclopentanone. The cyclopentanol was generated by the hydrogenation of unreacted cyclopentanone (or the cyclopentanone from the retro-aldol condensation of 2-cyclopentylidene cyclopentanone).

Scheme 1. Reaction Pathways for the Generation of 2-Cyclopentyl Cylopentanone, 2Cyclopentylidene Cyclopentanone and Cyclopentanonol. From the results shown in Figure 2, the mixture of Raney Co and KOH solution (denoted as Raney Co + KOH) exhibited the best performance among the investigated catalyst systems. Over

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it, 94.8% cyclopentanone conversion and 83.3% carbon yield of 2-cyclopentyl cylopentanone were obtained after reacted at 353 K for 6 h. For comparison, we also studied the catalytic performances of Raney Co and other alkali hydroxides. According to Figure 3, the carbon yields of 2-cyclopentyl cylopentanone over the Raney Co + NaOH and Raney Co + LiOH catalysts are obviously lower than that over the Raney Co + KOH catalyst. On the contrary, the carbon yields of cyclopentanol over the Raney Co + NaOH and Raney Co + LiOH catalysts are obviously higher than that over the Raney Co + KOH catalyst. This result can be rationalized because the base strength of KOH is higher than those of LiOH and NaOH. As we know, the higher base strength of the catalyst is favorable for the deprotonation (or the generation of carbanion) which is considered as the first step for the base-catalyzed aldol condensation reactions.

Conversion or carbon yield (%)

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

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100 80 60 40 20 0 H+ o KO yC ne a R

H+ i KO yN ne a R

H+ u KO yC ne a R

H+ e KO yF ne a R

Figure 2. Cyclopentanone conversions (black bars) and the carbon yields of 2-cyclopentyl cylopentanone (dark grey bars), 2-cyclopentylidene cyclopentanone (light grey bars) and cyclopentanonol (white bars) under the catalysis of KOH and Raney metals. Reaction conditions: 353 K, 8 h; 2.0 g cyclopentanone, 0.1 g Raney metal, 2.0 mL KOH solution (1.25 mol L-1).

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Conversion or carbon yield (%)

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100 80 60 40 20 0

H+ o KO ey C n Ra

+ OH o Na ey C n a R

H+ o LiO ey C n Ra

Figure 3. Cyclopentanone conversion (black bars) and the carbon yields of 2-cyclopentyl cylopentanone (dark grey bars), 2-cyclopentylidene cyclopentanone (light grey bars) and cyclopentanonol (white bars) under the catalysis of Raney Co and alkali hydroxides. Reaction conditions: 353 K, 8 h; 2.0 g cyclopentanone, 0.1 g Raney Co, 2.0 mL alkali hydroxide solution (1.25 mol L-1). Synthesis

of

2-cyclopentyl-5-(2-cyclopentylcyclopentylidene)cyclopentanone.

In the

second step, we explored the self-aldol condensation of the 2-cyclopentyl cyclopentanone under the catalysis of KOH. Based on the result of GC-MS analysis (see Figures S5-S6), 2-cyclopentyl5-(2-cyclopentylcyclopentylidene)cyclopentanone was detected as the predominate product from this reaction. This compound exists as a liquid at room temperature (see Figure S7). Therefore, it can be directly converted to 1-(3-cyclopentyl)cyclopentyl-2-cyclopentylcyclopentane by the solvent-free hydrodeoxygenation (see Scheme 2). From the results shown in Figure 4, it is noticed that the removal of water from the reaction system by vacuum distillation can significantly

increase

the

carbon

yield

of

2-cyclopentyl-5-(2-

cyclopentylcyclopentylidene)cyclopentanone over KOH catalyst. This phenomenon can be explained by two reasons: 1) The aldol condensation reactions are reversible. Therefore, the

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removal

of

water

is

favorable

for

the

formation

Page 10 of 22

of

2-cyclopentyl-5-(2-

cyclopentylcyclopentylidene)cyclopentanone from the pointview of reaction equilibrium. 2) The removal

of

water

can

also

promote

the

generation

of

2-cyclopentyl-5-(2-

cyclopentylcyclopentylidene)cyclopentanone by suppressing the retro-aldol condensation.

Scheme

2.

Reaction

Pathways

for

cyclopentylcyclopentylidene)cyclopentanone

the

Generation and

of

2-Cyclopentyl-5-(2-

1-(3-Cyclopentyl)cyclopentyl-2-

cyclopentylcyclopentane. Subsequently, we compared the catalytic performances of various alkali hydroxides (see Figure 5 and Figure S8). Among them, KOH exhibited the highest activity. Over it, high carbon yield (95.4%) and TON of 2-cyclopentyl-5-(2-cyclopentylcyclopentylidene)cyclopentanone were gained after the reaction was conducted at 423 K for 1 h. Similar as what we observed in the one-pot reaction of cyclopentanone and hydrogen, the high activity of KOH can be comprehended by its higher base strength.

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Conversion or carbon yield (%)

100

80

60

40

20

0 Vacuum conditions

Atomosphere pressure

Figure 4. 2-Cyclopentyl cyclopentanone conversion (black bars) and the carbon yield of 2cyclopentyl-5-(2-cyclopentylcyclopentylidene)cyclopentanone (light grey bars) over KOH. Reaction conditions: 423 K, 1 h at the system pressure of 0.1 MPa or ~3 kPa; 5.0 g cyclopentanone, 0.25 g KOH. 100

Conversion or carbon yield (%)

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

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80

60

40

20

0 LiOH

NaOH

KOH

Figure 5. 2-Cyclopentyl cyclopentanone conversions (black bars) and the carbon yields of 2cyclopentyl-5-(2-cyclopentylcyclopentylidene)cyclopentanone (light grey bars) over alkali hydroxides. Reaction conditions: 423 K, 1 h at the system pressure of ~3 kPa; 5.0 g 2-cyclopentyl cyclopentanone, 0.25 g alkali hydroxide.

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Conversion and yield (%)

100 80 60 40 20 0 360

380 400 420 Reaction temperature (K)

440

Figure 6. 2-Cyclopentyl cyclopentanone conversion (■) and the carbon yield of 2-cyclopentyl-5(2-cyclopentylcyclopentylidene)cyclopentanone (▲) over KOH as the function of reaction temperature. Reaction conditions: 1 h, ~3 kPa; 5.0 g 2-cyclopentyl cyclopentanone, 0.25 g KOH.

Conversion and carbon yield (%)

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

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100 80 60 40 20 0 0.0

0.5 1.0 Reaction time (h)

1.5

Figure 7. 2-Cyclopentyl cyclopentanone conversion (■) and the carbon yield of 2-cyclopentyl-5(2-cyclopentylcyclopentylidene)cyclopentanone (▲) over KOH as the function of reaction time. Reaction conditions: 423 K, ~3 kPa; 5.0 g 2-cyclopentyl cyclopentanone, 0.25 g KOH. The impacts of reaction temperature and reaction time on the performance of KOH catalyst were also explored. On the basis of Figures 6 and 7, the 2-cyclopentyl cyclopentanone conversion and carbon yield of 2-cyclopentyl-5-(2-cyclopentylcyclopentylidene)cyclopentanone over KOH

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increased with reaction temperature (or reaction time), reached the maximum after reacting at 423 K for 1 h, then leveled off. Hydrodeoxygenation (HDO). Finally, we also studied the solvent-free HDO of 2cyclopentyl-5-(2-cyclopentylcyclopentylidene)cyclopentanone

over

the

Ni-SiO2

catalyst.

According to the result of GC-MS analysis (see Figures S9-S12), the 2-cyclopentyl-5-(2cyclopentylcyclopentylidene)cyclopentanone

was

completely

converted

after

being

hydrodeoxygenated over the Ni-SiO2 catalyst under investigated conditions (533 K and 6 MPa). 1-(3-cyclopentyl)cyclopentyl-2-cyclopentylcyclopentane was detected as the predominate product. Meanwhile, small amounts of 1,3-dicyclopentyl cyclopentane and 2-cyclopentyl cyclopentane were also detected in the HDO product. The carbon yields of 1-(3-cyclopentyl)cyclopentyl-2cyclopentylcyclopentane and polycycloalkanes were measured as 88.5% and 99.0%, respectively (see Figure 8). As what has been reported in our previous work about other reaction system23, the Ni-SiO2

catalyst

is

stable

for

the

solvent-free

HDO

of

2-cyclopentyl-5-(2-

cyclopentylcyclopentylidene)cyclopentanone. No distinct deactivation was observed during the 50 h time on stream. To further verify the good stability of the Ni-SiO2 catalyst, we increased the space velocity of 2-cyclopentyl-5-(2-cyclopentylcyclopentylidene)cyclopentanone. From Figure S13,

we

can

see

that

the

Ni-SiO2

catalyst

is

stable

when

2-cyclopentyl-5-(2-

cyclopentylcyclopentylidene)cyclopentanone conversion is around 80%. No distinct deactivation was observed during the 50 h time on stream either. According our measurement, the density and the freezing point of the polycycloalkanes mixture obtained in this work were 0.943 g mL-1 and 233.7 K, respectively. These properties are comparable with those of JP-10 and the hydrogenated pinene dimers which have been reported in the previous work of Harvey10, 24, 25, Zou

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their co-workers (see Table 1). To the best of our knowledge, this density (0.943 g mL-1) is the highest among the reported lignocellulosic liquid hydrocarbon fuels. 100

80

Carbon yield (%)

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

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Carbon yield of di(cyclopentane) (%) Carbon yield of tri(cyclopentane) (%) Carbon yield of 1-(3-cyclopentyl)cyclopentyl -2-cyclopentylcyclopentane (%)

60

40

20

0 4

8

12

16

20

24

28

32

36

40

44

48

Time on stream (h)

Figure 8. Carbon yields of different cycloalkanes over the Ni-SiO2 catalyst as the function of reaction time. Reaction conditions: 533 K, 6.0 MPa, 1.80 g catalyst; 2-cyclopentyl-5-(2cyclopentylcyclopentylidene)cyclopentanone flow rate 0.04 mL min-1, hydrogen flow rate: 120 mL min-1.

Table 1. The densities and freezing points of JP-10 fuel, hydrogenated pinene dimers and the polycycloalkanes mixture obtained in this work. JP-10a

Hydrogenated

Polycycloalkanes mixture

pinene dimersa

obtained in this workb

Density (g mL-1)

0.94

0.938

0.943

Freezing point (K)

194

243

233.7

a According b

to the values reported in literature10.

Measured in this work.

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CONCLUSIONS Herein, we reported a new route for the production of a high density fuel, 1-(3cyclopentyl)cyclopentyl-2-cyclopentylcyclopentane, with cyclopenanone which can be derived from lignocellulose. This route is composed of three steps: In the first step, 2-cyclopentyl cyclopentanone was obtained by the one-pot reaction of cyclopentanone and hydrogen under the catalysis of different Raney metals and alkali hydroxides. Among the investigated catalysts, the Raney Co + KOH exhibited the best performance. Over this catalyst, 83.3% carbon yield of 2cyclopentyl cyclopentanone was obtained under mild conditions (353 K, 2 MPa). In the second step, 2-cyclopentyl-5-(2-cyclopentylcyclopentylidene)cyclopentanone was synthesized by the self-aldol condensation of 2-cyclopentyl cyclopentanone under the catalysis of alkali hydroxides. Lower system pressure is favorable for this reaction, which can be explained by reaction equilibrium and restraining the retro-aldol condensation. Among the investigated catalysts, KOH exhibited the highest activity, which can be comprehended by its higher base strength. In the third step, the 2-cyclopentyl-5-(2-cyclopentylcyclopentylidene)cyclopentanone which can be obtained at 95.4% carbon yield from the second step were further hydrodeoxygenated under solvent-free conditions. The Ni-SiO2 catalyst exhibited high activity and good stability for the HDO reaction. Over it, high carbon yields of 1-(3-cyclopentyl) cyclopentyl-2-cyclopentyl cyclopentane (88.5%) and polycycloalkanes (99.0%) were achieved. No evident deactivation was observed during the 50 h time on stream. The polycycloalkanes mixture as obtained has a density of 0.943 g mL-1 and a freezing point of 233.7 K. As a potential application, it can be blended into conventional high density fuels (such as JP-10) for rockets and missile propulsion.

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ASSOCIATED CONTENT Supporting Information The

Supporting

Information

is

available

free

of

charge

on

the

ACS Publications website. Blank experiment result for the aldol condensation of cyclopentanone under the catalysis of KOH solution. GC-MS chromatograms, 1H and

13C

NMR spectra and photo of the different

products, activity test results for the solvent-free self-aldol condensation of 2-cyclopentyl cylopentanone under the catalysis of equal moles of alkali hydroxide, the stability test of the NiSiO2 catalyst at high space velocity. AUTHOR INFORMATION Corresponding Author Prof.

Tao

Zhang,

Tel:

+86-411-84379015;

Fax:

+86-411-84691570;

E-mail:

[email protected] Prof. Ning Li, Tel.: +86-411-84379738, Fax: +86-411-84685940. E-mail: [email protected].

Notes The authors declare no competing financial interest. ACKNOWLEDGMENTS This work was funded by the National Natural Science Foundation of China (no. 21277140; 21476229, 21506213, 21690082, 21690084 and 21672210), Dalian Science Foundation for Distinguished Young Scholars (no. 2015R005), the Strategic Priority Research Program of the Chinese Academy of Sciences (XDB17020100), Department of Science and Technology of Liaoning Province (under contract of 2015020086-101) and 100-talent project of Dalian Institute

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of Chemical Physics (DICP). Dr. Wei Wang appreciates the Education Department of Shaanxi Provincial Government Research Project (no. 16JK1146), the Funds of Research Programs of Shaanxi University of Technology (no. SLGQD13(2)-1) for financial support.

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(17) Xia, Q.-N.; Cuan, Q.; Liu, X.-H.; Gong, X.-Q.; Lu, G.-Z.; Wang, Y.-Q., Pd/NbOPO4 multifunctional catalyst for the direct production of liquid alkanes from aldol adducts of furans. Angew. Chem. Int. Ed. 2014, 53, 9755-9760. (18) Prasomsri, T.; Shetty, M.; Murugappan, K.; Roman-Leshkov, Y., Insights into the catalytic activity and surface modification of MoO3 during the hydrodeoxygenation of lignin-derived model compounds into aromatic hydrocarbons under low hydrogen pressures. Energy Environ. Sci. 2014, 7, 2660-2669. (19) Sankaranarayanapillai, S.; Sreekumar, S.; Gomes, J.; Grippo, A.; Arab, G. E.; Head-Gordon, M.; Toste, F. D.; Bell, A. T., Catalytic upgrading of biomass-derived methyl ketones to liquid transportation fuel precursors by an organocatalytic approach. Angew. Chem. Int. Ed. 2015, 54, 4673-4677. (20) Hronec, M.; Fulajtarova, K., Selective transformation of furfural to cyclopentanone. Catal. Commun. 2012, 24, 100-104. (21) He, J.; Zhao, C.; Lercher, J. A., Ni-Catalyzed Cleavage of Aryl Ethers in the Aqueous Phase. J. Am. Chem. Soc. 2012, 134, 20768-20775. (22) Climent, M. J.; Corma, A.; Iborra, S.; Sabater, M. J., Heterogeneous Catalysis for Tandem Reactions. ACS Catal. 2014, 4, 870-891. (23) Yang, J.; Li, N.; Li, G.; Wang, W.; Wang, A.; Wang, X.; Cong, Y.; Zhang, T., Synthesis of renewable high-density fuels using cyclopentanone derived from lignocellulose. Chem. Commun. 2014, 50, 2572-2574. (24) Meylemans, H. A.; Quintana, R. L.; Harvey, B. G., Efficient conversion of pure and mixed terpene feedstocks to high density fuels. Fuel 2012, 97, 560-568. (25) Meylemans, H. A.; Baldwin, L. C.; Harvey, B. G., Low-temperature properties of renewable high-density fuel blends. Energy Fuels 2013, 27, 883-888.

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(26) Nie, G. K.; Zou, J. J.; Feng, R.; Zhang, X. W.; Wang, L., HPW/MCM-41 catalyzed isomerization and dimerization of pure pinene and crude turpentine. Catal. Today 2014, 234, 271-277.

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GRAPHICAL ABSTRACT

Density: 0.943 g mL-1 Freezing point: 233.7 K

Synthesis of Renewable High-Density Fuel with Cyclopentanone Derived from Hemicellulose Wei Wang, Ning Li*, Guangyi Li, Shanshan Li, Wentao Wang, Aiqin Wang, Yu Cong, Xiaodong Wang, Tao Zhang* A new synthetic route for renewable high density rocket fuel was developed with cyclopentanone which can be obtained from hemicellulose.

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