A metallocene cis-trans isomerization catalyst, its preparation method and use

Abstract

The application discloses a piperitone cis-trans isomerization catalyst and a preparation method and application thereof. The catalyst is prepared by an impregnation reaction method from a noble metal precursor and a carrier precursor. The noble metal precursor accounts for 0.1-5% of the mass of the carrier precursor in terms of the noble metal contained. The application first uses a supported noble metal catalyst to perform an isomerization reaction under a hydrogen-free (inert) condition. The catalyst is simple to prepare and operate. The obtained supported noble metal catalyst has good catalytic activity in isomerization of cis-piperitone into trans-piperitone. The conversion rate of the cis-piperitone can reach 13.5%, the selectivity of the trans-piperitone can reach 100%, and the yield of the trans-piperitone can reach 13.5%.

Description

TECHNICAL FIELD

[0001] The present application relates to the research field of catalyzing cis-olefins to isomerize into trans-olefins, in particular, supported noble metal catalyst catalyzing cis-piperylene to isomerize into trans-piperylene under hydrogen-free conditions. BACKGROUND

[0002] Tetrahydrophthalic anhydride (methyl tetrahydrophthalic anhydride) is a new type of fine chemical product indispensable to electronic and electromechanical industrial products. It has excellent properties such as lower freezing point, smaller volatility, lower toxicity, and long-term existence at room temperature. The epoxy resin curing agent synthesized from tetrahydrophthalic anhydride is widely used in processes such as pouring, pouring and sealing, encapsulation, molding, and adhesion, as well as in electronic and electrical insulation materials, glass fiber reinforced plastic composites, and the like. Among them, trans-piperylene is an effective component for synthesizing tetrahydrophthalic anhydride.

[0003] The by-products generated from catalytic cracking of petroleum and ethylene industry are mainly carbon five (C5) compounds, mainly including piperylene (PD), cyclopentadiene (CPD), and dicyclopentadiene (DCPD). Carbon five compounds are raw materials for synthesizing hexahydrophthalic anhydride and tetrahydrophthalic anhydride, but only trans-piperylene is an effective component for the synthesis reaction. Among the recovered carbon five after the reaction, it mainly contains cyclopentene, cyclopentane, isoprene, cis-piperylene (with the highest content, about 40%-50%), and unreacted trans-piperylene. For the recovered carbon five compounds, under suitable reaction conditions, the piperylene isomerization reaction is completed, part of the cis-piperylene isomerization reaction, and is converted into trans-piperylene, so that the content of trans-piperylene in the recovered carbon five by-products is increased, and it is reused in the original synthesis process, which can improve the utilization rate of the raw material, reduce the waste of energy, and effectively reduce the cost.

[0004] From a theoretical point of view, the stability of trans-piperylene is higher than that of cis-piperylene, so under suitable conditions, cis-piperylene can be converted into trans-piperylene. [Wang Z G, Liu H, Chen J T, et al. Theoretical study on the mechanism of cis-trans isomerization of piperylene [J]. Science and Technology Information, 2011, No. 357(01): 443-444.] It is mentioned that the activation energy of cis-trans conversion calculated at the MP2 / 6-311G** level is 12.35-15.76 kJ·mol -1 , which indicates that the conversion from cis to trans can be realized at a temperature slightly higher than room temperature. Currently, there are two types of reactions for isomerizing cis-piperylene into trans-piperylene, namely, photo-catalysis and thermal catalysis. The photo-catalysis is difficult to carry out large-scale industrialization due to the limitation of light source conditions. Secondly, in the reaction of thermal catalysis for isomerizing cis-piperylene into trans-piperylene, most of them are carried out in a hydrogen atmosphere, which has high safety requirements for the construction of reactors and workshops. The reaction of catalyzing cis-piperylene to convert into trans-piperylene under an inert gas (such as N2) atmosphere has not been reported.

[0005] Our research group designed a kind of noble metal catalyst, in inert gas atmosphere, and the appropriate temperature catalytic cis-piperylene isomerization into trans-piperylene, achieved higher yield, so that cis-piperylene has been fully utilized. The catalyst catalytic activity effect is good, high stability, for isomerization reaction provides a new research way. SUMMARY

[0006] The application aims to provide a kind of noble metal catalyst and its preparation method, and in the reaction of cis-piperylene isomerization into trans-piperylene. The noble metal catalyst of the application, wherein noble metal is active center, by adjusting the content of noble metal, realize the high efficiency isomerization of cis-piperylene into trans-piperylene under hydrogen-free condition.

[0007] The technical scheme of the application is as follows:

[0008] A kind of noble metal catalyst, which is made by impregnation reaction method from noble metal precursor and carrier precursor. The content of noble metal precursor in carrier precursor is 0.1-5% by weight, preferably 0.1-1%.

[0009] The noble metal precursor is selected from one or more of palladium nitrate, rhodium nitrate, silver nitrate, platinum nitrate, iridium nitrate, palladium chloride, rhodium chloride, silver chloride, platinum chloride, iridium chloride, palladium acetylacetone, rhodium acetylacetone, silver acetylacetone, platinum acetylacetone, iridium acetylacetone, preferably palladium nitrate, rhodium nitrate, silver nitrate, platinum nitrate, iridium nitrate.

[0010] The carrier precursor is zinc-based carrier precursor or silicon-based carrier precursor.

[0011] The zinc-based carrier precursor is selected from one or more of zinc oxide, zinc nitrate, zinc acetate, zinc glycinate, zinc gluconate, zinc acetylacetone, zinc oxalate, diethyl zinc, zinc chloride, zinc citrate, zinc sulfate, preferably zinc oxide, zinc nitrate, zinc acetate, zinc acetylacetone, zinc chloride.

[0012] The silicon-based carrier precursor is selected from one or more of ordinary SiO2, fumed SiO2, ZSM-5, SBA-15, SBA-16, Y-type molecular sieve, mordenite, erionite, chabazite, preferably fumed SiO2, ZSM-5, SBA-15.

[0013] Particularly preferably, the noble metal catalyst is made by impregnation reaction method from palladium acetylacetone and zinc oxide. The content of palladium acetylacetone in zinc oxide is 0.5% by weight.

[0014] Also particularly preferred, the supported noble metal catalyst is prepared by impregnation reaction method using palladium acetylacetonate, fumed SiO2; palladium acetylacetonate is 0.3% of the mass of fumed SiO2 in terms of the contained palladium.

[0015] The preparation method of the supported noble metal catalyst according to the present application is as follows:

[0016] The noble metal precursor and the carrier precursor are mixed uniformly in a solvent, the obtained mixture is subjected to impregnation reaction at 30-100℃ for 12-48h, and then the solvent is evaporated (preferably at 100-120℃) to obtain a powder solid, which is put into a blast oven after being ground thoroughly and is treated at 100-180℃ for 6-24h to obtain the supported noble metal catalyst;

[0017] The solvent used is selected from one or more of water, acetylacetone, N,N-dimethylformamide, ethanol, methanol, cyclohexane, n-hexane, acetone, acetic acid, ethylene glycol, toluene, chloroform, preferably water, acetylacetone, N,N-dimethylformamide, ethanol, methanol.

[0018] The supported noble metal catalyst according to the present application can be applied to the reaction of isomerization of cis-piperylene into trans-piperylene under hydrogen-free conditions. The specific application method is as follows:

[0019] The catalyst is put into a reaction kettle, 0.1-1MPa of nitrogen is flushed in as protective gas (to exclude other gases in the reaction kettle), carbon five compound raw material is added, and the reaction is carried out at 40-100℃, and the reaction time is 2-96h.

[0020] The present application has the following beneficial effects:

[0021] The present application realizes the isomerization of cis-piperylene into trans-piperylene under hydrogen-free conditions for the first time. The preparation of the catalyst according to the present application is simple, the obtained supported noble metal catalyst has good catalytic isomerization activity, and the yield of the obtained trans-piperylene reaches 13.5%. DETAILED DESCRIPTION

[0022] The present application is further described below through specific examples, but the scope of protection of the present application is not limited to this.

[0023] Example 1

[0024] Preparation of 0.1% Pd / ZnO by impregnation reaction method

[0025] Take 0.0029 g of palladium acetylacetonate, dissolve in a 100 mL single-mouth round-bottom flask containing 57.3 mL of acetylacetone, stir at 50°C and 450 r / min for 30 min. After the palladium acetylacetonate is completely dissolved, 1.000 g of zinc oxide is added, and stirring at 50°C is continued for 24 h. The solution is transferred to a 100 mL beaker, and is evaporated to dryness in an oil bath at 120°C and a rotation speed of 300 r / min. Finally, drying in a 150°C oven for 12 h, and is recorded as catalyst A.

[0026] Take 0.2 g of catalyst, reduce in a H2 atmosphere with a flow rate of 20 mL / min at 270°C for 4 h. Then load into a 50 mL reaction kettle, introduce nitrogen at room temperature, wait for 2 min, then exclude the nitrogen, repeat this operation 3 times, and then exclude the air in the reaction kettle, and finally flush in 0.4 MPa pressure of nitrogen, and add 18.48 g (25 mL) of carbon five mixture. The reaction temperature is 50°C and 100°C, respectively, the stirring speed of the reaction is 800 r / min, and the reaction time is 4 h.

[0027] Among them, the reaction raw material is derived from the carbon five mixture recovered from the synthesis of tetrahydrophthalic anhydride reaction, mainly including cis-piperylene, trans-piperylene, cyclopentene, cyclopentane, 2-pentene, etc.

[0028] Example 2

[0029] The preparation method of catalyst B and the evaluation method of the catalyst are consistent with example 1, but the amount of palladium acetylacetonate is 0.0086 g, and the other contents remain unchanged.

[0030] Example 3

[0031] The preparation method of catalyst C and the evaluation method of the catalyst are consistent with example 1, but the content of palladium acetylacetonate is 0.0143 g, and the content of other reagents remains unchanged.

[0032] Example 4

[0033] The preparation method of catalyst D and the evaluation method of the catalyst are consistent with example 1, but the content of palladium acetylacetonate is 0.0230 g, and the content of other reagents remains unchanged.

[0034] Example 5

[0035] The preparation method of catalyst E and the evaluation method of the catalyst are consistent with example 1, but the content of palladium acetylacetonate is 0.0286 g, and the content of other reagents remains unchanged.

[0036] The catalyst is used in the reaction of cis-piperylene isomerization to trans-piperylene in a reaction kettle, and the catalytic performance is shown in Table 1.

[0037] Table 1 Performance of Pd / ZnO catalyst

[0038]

[0039] Note: The product was analyzed by manual injection into the chromatograph (FuLi GC97902 II) FID detector, with a PoraPLOT, 60 m x 0.32 nm, DF = 10 μm with 1 PT (couple 2 x 30 with Ultra interconnector) Fused Silica column.

[0040] The activity data in Table 1 shows that with the increase of noble metal content, the isomerization activity first increases and then decreases, the selectivity of trans-piperylene remains 100%, and the yield shows a trend of first increasing and then decreasing. When the content of noble metal reaches 0.5%, the catalyst has the best catalytic effect, and the highest yield is 13.5%. Excessive noble metal will cause the activity of the catalyst to decrease.

[0041] Comparative Example 1

[0042] In order to compare the influence of different carriers on the catalytic activity, the same preparation method as in Example 1 was used to obtain a catalyst with fumed silica as the carrier. 0.1% Pd / SiO2, 0.3% Pd / SiO2, 0.5% Pd / SiO2, 0.8% Pd / SiO2, and 1% Pd / SiO2 are denoted as F, G, H, I, and J, respectively, and are applied to the reaction of isomerization of cis-piperylene to trans-piperylene.

[0043] Except for the different catalysts, the reaction conditions are exactly the same as in Example 1. The catalysts were used to catalyze the reaction of isomerization of cis-piperylene to trans-piperylene in a reaction kettle, and the catalytic performance is shown in Table 2.

[0044] Table 2 Performance of Pd / SiO2 catalysts

[0045]

[0046]

[0047] The activity data in Table 2 also shows that when the zinc-based carrier of the catalyst is replaced by fumed silica, with the increase of noble metal content, the isomerization activity also first increases and then decreases, the selectivity of trans-piperylene remains 100%, and the yield shows a trend of first increasing and then decreasing. When the content of noble metal is 0.3%, the highest yield is 12.9%. Further increasing the content of noble metal will cause the activity of the catalyst to decrease.

Claims

1. Use of a supported noble metal catalyst in a reaction of cis-piperylene isomerization to trans-piperylene under hydrogen-free conditions. The supported noble metal catalyst is prepared by an impregnation reaction method from a noble metal precursor and a carrier precursor; the noble metal precursor accounts for 0.1-5% of the mass of the carrier precursor in terms of the noble metal contained therein. The noble metal precursor is selected from one or more of palladium nitrate, rhodium nitrate, silver nitrate, palladium chloride, rhodium chloride, silver chloride, platinum chloride, iridium chloride, palladium acetylacetonate, rhodium acetylacetonate, and iridium acetylacetonate. The carrier precursor is a zinc-based carrier precursor or a silicon-based carrier precursor.

2. Use according to claim 1, wherein The zinc-based carrier precursor is zinc oxide.

3. The use according to claim 1, wherein The silicon-based carrier precursor is selected from one or more of ordinary SiO2, fumed SiO2, ZSM-5, SBA-15, SBA-16, Y-type molecular sieve, mordenite, erionite, and chabazite.

4. The use according to claim 1, wherein The supported noble metal catalyst is prepared by an impregnation reaction method from palladium acetylacetonate and zinc oxide; the palladium acetylacetonate accounts for 0.5% of the mass of the zinc oxide in terms of the palladium contained therein.

5. The use according to claim 1, wherein The supported noble metal catalyst is prepared by an impregnation reaction method from palladium acetylacetonate and fumed SiO2; the palladium acetylacetonate accounts for 0.3% of the mass of the fumed SiO2 in terms of the palladium contained therein.

6. The use according to claim 1, wherein The preparation method of the supported noble metal catalyst is as follows: The noble metal precursor and the carrier precursor are mixed uniformly in a solvent, the obtained mixture is subjected to an impregnation reaction at 30-100 ℃ for 12-48 h, after which the solvent is evaporated to dryness, a powdery solid is obtained, which is ground thoroughly and then placed in a blast oven, and is treated at 100-180 ℃ for 6-24 h to obtain the supported noble metal catalyst.

7. Use according to claim 6, wherein The solvent used is selected from one or more of water, acetylacetone, N,N-dimethylformamide, ethanol, methanol, cyclohexane, n-hexane, acetone, acetic acid, ethylene glycol, toluene, and chloroform.

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