Preparation method and application of Ti-based material loaded Ru-based catalyst

Abstract

The invention provides a preparation method of a Ti-based material supported Ru-based catalyst and application of the Ti-based material supported Ru-based catalyst in preparation of cyclohexene by partial hydrogenation of benzene. The auxiliaries 1 and 2 are added into the Ti-based material at the same time, and the high cyclohexene yield can be obtained under the condition of the low Ru content. The addition of the assistant increases the surface alkalinity of the catalyst, thereby being more beneficial to the adsorption of benzene and the desorption of cyclohexene, finally promoting the conversion of benzene and avoiding the excessive hydrogenation of cyclohexene to generate cyclohexane. In addition, electron interaction exists between the auxiliary agent and the metal Ru. Due to the fact that the electronegativity of the auxiliary is high, electrons in the metal Ru can be adsorbed, so that the electrons are transferred, and Ru delta + with part of positive charges is generated. The presence of Ru delta < + > can reduce the hydrogenation capacity of the catalyst, thereby avoiding excessive hydrogenation of cyclohexene to generate cyclohexane. In addition, according to the Ru-based catalyst, the content of metal Ru is far lower than that of an industrial catalyst (the content of Ru is 10 wt%).

Description

Technical Field

[0001] The invention belongs to the technical field of catalyst preparation, and particularly relates to a preparation method of a Ti-based material-loaded Ru-based catalyst and application thereof. Background Art

[0002] Cyclohexene is an important industrial raw material that can be used to synthesize high value-added chemicals such as cyclohexanol, caprolactam and adipic acid. Cyclohexene can be obtained by partial hydrogenation of benzene, dehydration of cyclohexanol, dehydrogenation of cyclohexane and Birch reduction. Among them, partial hydrogenation of benzene to produce cyclohexene has become the most commonly used method for cyclohexene production due to the advantages of easy availability of raw materials-benzene, low price, simple reaction process and easy operation. Thermodynamically, the standard Gibbs free energy change (-98kJ / mol) of benzene hydrogenation to cyclohexane is much smaller than the standard Gibbs free energy change (-23kJ / mol) of benzene hydrogenation to cyclohexene. Therefore, thermodynamically, benzene hydrogenation is more likely to produce cyclohexene. Selecting appropriate catalysts and reaction systems is of great significance to improving the yield of cyclohexene.

[0003] At present, the academic and industrial circles mainly use the following three methods to improve the yield of cyclohexene. 1) Adding additives. For example, Zhou et al. [Zhou G, et al. J Catal 2014; 311: 393-403] added additive B to Ru / ZrO2, and used the increase in acidity and the electronic interaction between B and Ru to improve the yield of cyclohexene. 2) Adding hydrophilic substances. For example, patent CN105664931A wraps SiO2 on the surface of Ru particles to improve the hydrophilicity of the catalyst, thereby avoiding the cyclohexene generated by the reaction from being enriched on the catalyst surface and over-hydrogenated to produce cyclohexane. Patent CN103785378A doped SiO2 into TiO2 to prepare Ti-Si composite materials, and used the hydrophilicity of SiO2 to improve the hydrophilicity of the catalyst surface. 3) Adding organic substances such as alcohols. For example, Estevam et al. [Estevam V, et al. Catal Commun 2003; 4: 91-96] added methanol, ethanol, ethylene glycol and propylene glycol to Ru-based catalysts, and the activity test results showed that the appropriate addition of alcohol organic matter can increase the cyclohexene yield to a certain extent. Sun et al. [Sun H, et al. Chem Eng J 2013; 218: 415-424] added ethanol, ethylene glycol and polyethylene glycol to Ru-Zn catalysts, and the catalytic performance test results showed that the appropriate addition of polyethylene glycol can increase the cyclohexene yield to a certain extent. In industry, benzene partial hydrogenation catalysts have gone through two stages: unsupported Ru-Zn catalysts and supported Ru-based catalysts. When China introduced Asahi Kasei's benzene partial hydrogenation process to produce cyclohexene from Japan in the early days, the catalyst used was a non-supported Ru-Zn catalyst with a Ru content of up to 20wt% to 30wt%, which was very expensive. Subsequently, the Sinopec Institute of Petroleum and Chemical Industry and Zhengzhou University improved the catalyst and developed a Ru-Zn-ZrO2 catalyst with the Ru content reduced to about 10wt%. Although the cost of this new catalyst has been reduced, the precious metal content is still high, and the catalyst cost burden is relatively large. Therefore, developing a low-Ru content catalyst with industrial application value is a huge challenge faced by both industry and academia. Summary of the invention

[0004] The present invention aims to provide a method for preparing a catalyst for preparing cyclohexene by partial hydrogenation of benzene, so as to overcome the difficulties faced by existing catalysts, such as low cyclohexene yield and high cost caused by high precious metal content. The Ru-based catalyst provided by the present invention is mainly used for preparing cyclohexene by partial hydrogenation of liquid benzene, has the advantages of low precious metal Ru content, low cost burden, etc., and has certain price advantages in industrial production.

[0005] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0006] (1) Tetraethyl titanate, additives 1 and 2 are added to water, the pH value is adjusted to 8.5-9.0 with aqueous ammonia, the mixture is heated to reflux, filtered, dried overnight, and then calcined at high temperature;

[0007] (2) Dispersing the sample obtained in step 1 in water, adding Ru salt, stirring and dissolving, adding urea or N-phenylurea, heating to reflux, filtering, drying overnight, and then calcining at high temperature;

[0008] (3) The sample obtained in step 2 is dispersed in water, and hydrazine hydrate is added to reduce the metal Ru.

[0009] In some preferred embodiments, the additive 1 in step (1) is one or more of Li salt, Na salt, K salt and Cs salt. Wherein, the Li salt is one or more of LiNO3, Li2CO3, LiCl and Li2SO4; the Na salt is one or more of NaNO3, Na2CO3, NaCl and Na2SO4; the K salt is one or more of KNO3, K2CO3, KCl and K2SO4; the Cs salt is one or more of CsNO3, Cs2CO3, CsCl and Cs2SO4; the content of the additive 1 is 1wt% to 10wt%.

[0010] In some preferred embodiments, the auxiliary agent 2 in step (1) is one or more of a Zn salt, a La salt and a Co salt. The Zn salt is one or more of Zn(NO3)2·6H2O, [ZnCO3]2·[Zn(OH)2]3, ZnCl2 and ZnSO4; the La salt is one or more of La(NO3)3, La2(CO3)3·xH2O, LaCl3 and La2(SO4)3; the Co salt is one or more of Co(NO3)2·6H2O, CoCO3, CoCl2 and CoSO4·H2O; the content of the auxiliary agent 2 is 1wt% to 10wt%.

[0011] In some preferred embodiments, the calcination temperature in step (1) is 350° C. to 800° C., and the calcination time is 3 h to 8 h.

[0012] In some preferred embodiments, the Ru salt in step (2) is one or more of RuCl3, Ru(acac)3 and Ru(NO)(NO3)3.

[0013] In some preferred embodiments, the content of metal Ru in step (2) is 0.5 wt% to 5.0 wt%.

[0014] In step (2), the amount of N-phenylurea added is 10-50 times the mass of the Ru salt. The amount of urea or N-phenylurea used is slightly in excess of the mass of the Ru salt.

[0015] The present invention provides a method for preparing a Ru-based catalyst supported by a Ti-based material according to the technical solution, and an application of the catalyst in a reaction of partially hydrogenating benzene to produce cyclohexene.

[0016] The beneficial results of the present invention are:

[0017] The present invention provides a preparation method of a Ti-based material-supported Ru-based catalyst and its application in a liquid phase partial hydrogenation reaction to produce cyclohexene. Thanks to the synergistic effect of additives 1 and 2, the catalyst involved in the present invention can quickly convert benzene into cyclohexene under conditions of low Ru content and maintain a high cyclohexene yield. This is mainly because the addition of additives 1 and 2 can change the acidity and alkalinity of the catalyst surface, and there is an electronic interaction between the additives 1 and 2 and the metal Ru, attracting some electrons to transfer from Ru to the additives, thereby generating Ru with a partial positive charge. δ+ . δ+ The presence of can weaken the hydrogenation ability of the Ru-based catalyst, thereby avoiding excessive hydrogenation of the product cyclohexene to form cyclohexane. DETAILED DESCRIPTION

[0018] The present invention provides a method for preparing a Ti-based material-supported Ru-based catalyst, which is applied to the reaction of preparing cyclohexene by partial hydrogenation of benzene. In the present invention, the catalytic performance evaluation device used is a kettle reactor, which is similar to the production device of preparing cyclohexene by partial hydrogenation of benzene in industrial production.

[0019] In the present invention, unless otherwise specified, the evaluation method for preparing cyclohexene by partial hydrogenation of benzene is as follows: a certain amount of catalyst and water are taken, loaded into a kettle reactor, filled with hydrogen and then emptied, and this process is repeated three times to exhaust the air in the kettle. After the pressure is held down and leaks are detected, the reaction temperature is raised, and after reaching the target temperature, benzene is added to start the timing reaction.

[0020] In the present invention, unless otherwise specified, the reaction conditions for preparing cyclohexene by partial hydrogenation of benzene are: 5.0 MPa, 140° C., rotation speed 1000 r / min, catalyst 1 g, benzene 50 mL, water 100 mL.

[0021] In the present invention, unless otherwise specified, the benzene conversion rate and cyclohexene selectivity listed in Table 1 are obtained under the condition of the highest cyclohexene yield.

[0022] To further illustrate the present invention, the following embodiments are described in detail, but the protection scope of the present invention is not limited to the following embodiments.

[0023] Example 1

[0024] Take 14.3g of tetraethyl titanate and disperse it in 100mL of water, add 0.19g of NaNO3 as additive 1, 0.25g of Co(NO3)2·6H2O as additive 2, add ammonia water to adjust the pH value to 8.5-9.0, heat and reflux at 80℃ for 5h, filter, dry at 100℃ overnight, and then calcine at 600℃ to obtain a Ti-based material doped with Na and Co, abbreviated as Na-Co-Ti. The mass fractions of Na and Co are both 1.0wt%.

[0025] The above Na-Co-Ti was dispersed in 150 mL of water, and 0.18 g of RuCl3 was added. After the metal salt was completely dissolved, 5 g of urea was added, and the mixture was heated to reflux at 80 °C for 12 h. The mixture was filtered and washed with deionized water until there were no Cl ions in the filtrate. Finally, the mixture was dried at 100 °C overnight to obtain a catalyst precursor.

[0026] The catalyst precursor was dispersed in 200 mL of water, 5 g of hydrazine hydrate was added, and after stirring for 1 hour, it was filtered and washed with deionized water until the solution was neutral. The obtained product was a Ru-based catalyst supported by a Ti-based material.

[0027] Example 2

[0028] A Ti-based material-supported Ru-based catalyst was prepared with reference to Example 1. The difference from Example 1 is that the mass fractions of Na and Co in this example are both 2.5 wt %.

[0029] Example 3

[0030] A Ti-based material-supported Ru-based catalyst was prepared with reference to Example 1. The difference from Example 1 is that the mass fractions of Na and Co in this example are both 5.0 wt %.

[0031] Example 4

[0032] Referring to Example 2, a Ti-based material loaded with Ru-based catalyst was prepared. The difference from Example 2 is that in this example, the Na salt is Na2CO3 and the Co salt is CoCO3.

[0033] Example 5

[0034] Referring to Example 2, a Ti-based material loaded Ru-based catalyst was prepared. The difference from Example 2 is that the auxiliary agent 1 in this example is LiNO 3 .

[0035] Example 6

[0036] Referring to Example 2, a Ti-based material loaded Ru-based catalyst was prepared. The difference from Example 2 is that the auxiliary agent 1 in this example is KNO3.

[0037] Example 7

[0038] Referring to Example 2, a Ti-based material loaded Ru-based catalyst was prepared. The difference from Example 2 is that the auxiliary agent 1 in this example is CsNO3.

[0039] Example 8

[0040] Referring to Example 2, a Ti-based material loaded Ru-based catalyst was prepared. The difference from Example 2 is that the auxiliary agent 2 in this example is Zn(NO3)2·6H2O.

[0041] Example 9

[0042] Referring to Example 2, a Ti-based material loaded Ru-based catalyst was prepared. The difference from Example 2 is that the auxiliary agent 2 in this example is La(NO3)3.

[0043] Example 10

[0044] Referring to Example 2, a Ti-based material loaded Ru-based catalyst was prepared. The difference from Example 2 is that in this example, the auxiliary agent 1 is LiNO3 and the auxiliary agent 2 is Zn(NO3)2·6H2O.

[0045] Embodiment 11

[0046] Referring to Example 2, a Ti-based material loaded Ru-based catalyst was prepared. The difference from Example 2 is that in this example, the auxiliary agent 1 is LiNO3 and the auxiliary agent 2 is La(NO3)3.

[0047] Example 12

[0048] Referring to Example 2, a Ti-based material loaded Ru-based catalyst was prepared. The difference from Example 2 is that in this example, the auxiliary agent 1 is KNO3 and the auxiliary agent 2 is Zn(NO3)2·6H2O.

[0049] Embodiment 13

[0050] Referring to Example 2, a Ti-based material loaded Ru-based catalyst was prepared. The difference from Example 2 is that in this example, the auxiliary agent 1 is KNO3 and the auxiliary agent 2 is La(NO3)3.

[0051] Embodiment 14

[0052] Referring to Example 2, a Ti-based material loaded Ru-based catalyst was prepared. The difference from Example 2 is that in this example, the auxiliary agent 1 is CsNO3 and the auxiliary agent 2 is Zn(NO3)2·6H2O.

[0053] Embodiment 15

[0054] Referring to Example 2, a Ti-based material loaded Ru-based catalyst was prepared. The difference from Example 2 is that in this example, the auxiliary agent 1 is CsNO3 and the auxiliary agent 2 is La(NO3)3.

[0055] Example 16

[0056] Take 14.3g of tetraethyl titanate and disperse it in 100mL of water, add 0.19g of NaNO3 as additive 1, 0.25g of Co(NO3)2·6H2O as additive 2, add ammonia water to adjust the pH value to 8.5-9.0, heat and reflux at 80℃ for 5h, filter, dry at 100℃ overnight, and then calcine at 600℃ to obtain a Ti-based material doped with Na and Co, abbreviated as Na-Co-Ti. The mass fractions of Na and Co are both 1.0wt%.

[0057] The above Na-Co-Ti was dispersed in 150 mL of water, and 0.18 g of RuCl3 was added. After the metal salt was completely dissolved, 5 g of N-phenylurea was added, and the mixture was heated to reflux at 80 °C for 12 h. The mixture was filtered and washed with deionized water until there were no Cl ions in the filtrate. Finally, the mixture was dried at 100 °C overnight to obtain a catalyst precursor.

[0058] The catalyst precursor was dispersed in 200 mL of water, 5 g of hydrazine hydrate was added, and after stirring for 1 hour, it was filtered and washed with deionized water until the solution was neutral. The obtained product was a Ru-based catalyst supported by a Ti-based material.

[0059] Comparative sample 1

[0060] Referring to Example 2, a Ti-based material loaded Ru-based catalyst was prepared. The difference from Example 2 is that there are no additives 1 and 2 in this example.

[0061] Comparative sample 2

[0062] Referring to Example 2, a Ti-based material loaded Ru-based catalyst was prepared. The difference from Example 2 is that there is no auxiliary agent 1 in this example.

[0063] Comparative sample 3

[0064] Referring to Example 2, a Ti-based material loaded Ru-based catalyst was prepared. The difference from Example 2 is that there is no auxiliary agent 2 in this example.

[0065] The above samples were evaluated for benzene partial hydrogenation activity. The evaluation conditions were as described above. The catalytic activity test results are listed in Table 1. From the implementation results, the simultaneous addition of additives 1 and 2 can greatly increase the cyclohexene yield. This is mainly because the addition of additives 1 and 2 can change the acidity and alkalinity of the catalyst surface, increase the benzene adsorption capacity and cyclohexene desorption capacity, and interact with metal Ru to attract some electrons from Ru to the additives, thereby generating some positively charged Ru. δ+ . δ+The presence of can weaken the hydrogenation ability of the Ru-based catalyst, thereby preventing the product cyclohexene from being over-hydrogenated to form cyclohexane. In addition, thanks to the promoting effect of the additives 1 and 2, the catalyst of the present invention can obtain a cyclohexene yield of 50 mol% at a lower Ru content, the metal Ru content is much less than that of the industrial catalyst, and no additional additive zinc sulfate needs to be added during the reaction.

[0066] Table 1. Example benzene partial hydrogenation performance results.

[0067]

[0068]

Claims

1. A method for preparing a Ti-based material-supported Ru-based catalyst, characterized in that: The following steps are involved: (1) Tetraethyl titanate, additives 1 and 2 are added to water, the pH value is adjusted to 8.5-9.0 with aqueous ammonia, the mixture is heated to reflux, filtered, dried overnight, and then calcined at high temperature; (2) Dispersing the sample obtained in step 1 in water, adding Ru salt, stirring and dissolving, adding urea or N-phenylurea, heating to reflux, filtering, drying overnight, and then calcining at high temperature; (3) The sample obtained in step 2 is dispersed in water, and hydrazine hydrate is added to reduce the metal Ru.

2. The method according to claim 1, characterized in that: In step (1), the auxiliary agent 1 is one or more of Li salt, Na salt, K salt and Cs salt; Wherein, the Li salt is one or more of LiNO3, Li2CO3, LiCl and Li2SO4; The Na salt is one or more of NaNO3, Na2CO3, NaCl and Na2SO4; The K salt is one or more of KNO3, K2CO3, KCl and K2SO4; The Cs salt is one or more of CsNO3, Cs2CO3, CsCl and Cs2SO4; The content of the auxiliary agent 1 is 1wt% to 10wt%.

3. The method according to claim 1, characterized in that: In step (1), the auxiliary agent 2 is one or more of Zn salt, La salt and Co salt; wherein the Zn salt is one or more of Zn(NO3)2·6H2O, [ZnCO3]2·[Zn(OH)2]3, ZnCl2 and ZnSO4; La salt is one or more of La(NO3)3, La2(CO3)3·xH2O, LaCl3 and La2(SO4)3; The Co salt is one or more of Co(NO3)2·6H2O, CoCO3, CoCl2 and CoSO4·H2O; The content of the auxiliary agent 2 is 1 wt% to 10 wt%.

4. The method according to claim 1, characterized in that: In step (1), the heating reflux reaction temperature is 50-100° C., and the reflux reaction time is 3-5 h.

5. The method according to claim 1, characterized in that: In step (1), the calcination temperature is 350° C. to 800° C., and the calcination time is 3 h to 8 h.

6. The method according to claim 1, characterized in that: In step (2), the Ru salt is one or more of RuCl3, Ru(acac)3 and Ru(NO)(NO3)3; the Ru content is 0.5wt% to 5.0wt%.

7. The method according to claim 6, characterized in that: In step (2), the amount of urea or N-phenylurea added is 10-50 times the mass of the Ru salt.

8. The method according to claim 1, characterized in that: In step (2), the heating reflux reaction temperature is 50-100° C., and the reflux reaction time is 8-12 h.

9. The method according to claim 1, characterized in that: In step (2), the calcination temperature is 350° C. to 800° C., and the calcination time is 3 h to 12 h.

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