阅读说明：本技术 一种L-苹果酸插层镁铝水滑石负载钌催化剂催化α-蒎烯加氢制备顺式蒎烷的方法 (Method for preparing cis-pinane by catalyzing hydrogenation of alpha-pinene with L-malic acid intercalation magnalium hydrotalcite loaded ruthenium catalyst ) 是由 胡银 陈伟 章芬 王玲玲 宋卫国 韩飞 于 2021-09-30 设计创作，主要内容包括：本发明公开了一种L-苹果酸插层镁铝水滑石负载钌催化剂催化α-蒎烯加氢制备顺式蒎烷的方法,催化剂为Ru/Mg-Al-L-(-)-MA LDH,Ru/Mg-Al-L-(-)-MA LDH复合催化剂与α-蒎烯的质量比为0.1:100,二者混合,反应温度为100℃～140℃,氢气压力为2～4MPa,反应得到顺式蒎烷。本发明所采用Ru/Mg-Al-L-(-)-MA LDH复合催化剂作为α-蒎烯加氢催化剂,制备工艺简单,在低温下就能高效催化α-蒎烯加氢合成顺式蒎烷,转化率高,选择性高,优于同类非均相催化剂。(The invention discloses a method for preparing cis-pinane by catalyzing alpha-pinene hydrogenation by using an L-malic acid intercalation magnalium hydrotalcite loaded ruthenium catalyst, wherein the catalyst is Ru/Mg-Al-L- (-) -MA LDH, the mass ratio of the Ru/Mg-Al-L- (-) -MA LDH composite catalyst to alpha-pinene is 0.1:100, the Ru/Mg-Al-L- (-) -MA LDH composite catalyst and the alpha-pinene are mixed, the reaction temperature is 100-140 ℃, the hydrogen pressure is 2-4 MPa, and the cis-pinane is obtained by reaction. The Ru/Mg-Al-L- (-) -MA LDH composite catalyst adopted by the invention is used as the alpha-pinene hydrogenation catalyst, the preparation process is simple, the cis-pinane can be synthesized by efficiently catalyzing the alpha-pinene hydrogenation at low temperature, the conversion rate is high, the selectivity is high, and the method is superior to the similar heterogeneous catalyst.)

1. A method for preparing cis-pinane through hydrogenation of alpha-pinene under catalysis of an L-malic acid intercalation magnalium hydrotalcite loaded ruthenium catalyst is characterized in that the mass ratio of ruthenium to the L-malic acid intercalation magnalium hydrotalcite in a composite catalyst is 3-10: 100, the mass ratio of the L-malic acid intercalation magnalium hydrotalcite loaded ruthenium composite catalyst to the alpha-pinene is 0.1:100, the ruthenium and the L-malic acid intercalation magnalium hydrotalcite loaded ruthenium composite catalyst are mixed, the reaction temperature is 90-140 ℃, the hydrogen pressure is 2-4 MPa, and the cis-pinane is prepared after complete reaction.

2. The method for preparing cis-pinane by catalyzing hydrogenation of alpha-pinene with the L-malic acid intercalated magnesium aluminum hydrotalcite supported ruthenium catalyst as claimed in claim 1, which comprises the following steps:

adding 50g of alpha-pinene into a reaction kettle, adding 0.05g of the prepared malic acid intercalation magnalium hydrotalcite loaded ruthenium composite catalyst according to the mass ratio of the catalyst to the alpha-pinene of 0.1:100, and sealing the reaction kettle;

replacing three to four times by using hydrogen under the gauge pressure of 2.5-3.5 MPa, detecting leakage, and confirming that the reaction kettle is well sealed;

and opening a hydrogen inlet valve, adjusting the pressure in the kettle to be 2-4 MPa, opening the reaction kettle, raising the temperature, and reacting at 100-140 ℃.

3. The method for preparing cis-pinane by catalyzing hydrogenation of alpha-pinene through the L-malic acid intercalation magnalium hydrotalcite supported ruthenium catalyst as claimed in claim 2, wherein in the step (c), the stirring speed is 500r/min, and the reaction time is 5 h.

4. An L-malic acid intercalated magnesium-aluminum hydrotalcite supported ruthenium catalyst for synthesizing cis-pinane through alpha-pinene hydrogenation is characterized in that the mass ratio of ruthenium to L-malic acid intercalated magnesium-aluminum hydrotalcite is 3-10: 100.

5. The L-malic acid intercalated magnesium aluminum hydrotalcite supported ruthenium catalyst for synthesizing cis-pinane by hydrogenating alpha-pinene as claimed in claim 4, wherein the L-malic acid intercalated magnesium aluminum hydrotalcite is prepared from Mg (NO)₃)₂·6H₂O、Al(NO₃)₃·9H₂The O-malic acid and the L-malic acid are mixed and reacted according to the molar ratio of 2:1: 1.

6. A preparation method of L-malic acid intercalation magnalium hydrotalcite loaded ruthenium catalyst for synthesizing cis-pinane by alpha-pinene hydrogenation is characterized in that Mg (NO) is added according to a molar ratio of 2:1₃)₂·6H₂O and Al (NO)₃)₃·9H₂Dissolving O in deionized water, and mixing the amount of substance with Al³⁺Dissolving equal L-malic acid in deionized water, slowly mixing the two solutions, adjusting the pH value of the mixed solution to be alkalescent by using a sodium hydroxide solution, standing, sealing in a reaction container, placing in a constant-temperature oven for a period of time, cooling to room temperature after reaction, and centrifuging, washing and drying the product to obtain L-malic acid intercalated magnesium-aluminum hydrotalcite; adding RuCl according to the mass ratio of Ru to L-malic acid intercalated magnesium-aluminum hydrotalcite of 1-10: 100₃Standing at normal temperature for reaction for a period of time, then heating and adding a proper amount of sodium borohydride solution, and reactingAnd cooling to room temperature, centrifuging, washing and drying to obtain the malic acid intercalation magnalium hydrotalcite-loaded ruthenium composite catalyst.

7. The method for preparing the L-malic acid intercalated magnesium aluminum hydrotalcite supported ruthenium catalyst for synthesizing the cis-pinane by hydrogenating the alpha-pinene as claimed in claim 6, which is characterized by comprising the following steps:

weighing 0.02mol of Mg (NO)₃)₂·6H₂O and 0.01mol of Al (NO)₃)₃·9H₂Dissolving O in 30mL of deionized water to obtain solution A, weighing 0.01mol of L-malic acid, and dissolving in 30mL of deionized water to obtain solution B;

dropping A into B, dropping 1mol/L sodium hydroxide solution, adjusting pH value to about 10.5 to obtain suspension, standing for 1h, placing the suspension in a reaction kettle, sealing by a stainless steel jacket, and keeping for 6h in a constant-temperature oven at 150 ℃;

③ after the reaction is finished, the reaction kettle is naturally cooled to room temperature, the product is centrifuged and washed by deionized water until the pH value is equal to 7, and is dried for 12 hours at 80 ℃ to obtain Mg-Al-L- (-) -MA LDH;

weighing 0.1g of Mg-Al-L- (-) -MA LDH obtained from the third step, adding into a conical flask, adding 250mL of deionized water into the conical flask, and performing ultrasonic treatment for 1 h;

fifthly, adding Na into the conical flask after the ultrasonic treatment is finished₂CO₃Adjusting the pH value of the solution in the conical flask to be 9-10;

sixthly, heating to 35 ℃, and adding 0.01-0.1 mmol of RuCl according to the mass ratio of Ru to Mg-Al-L- (-) -MA LDH of 1-10: 100₃Keeping the temperature at 35 ℃ for 3 h;

seventhly, after keeping at 35 ℃ for 3 hours, heating to 95 ℃, adding 0.2-2 mL of 300mM sodium borohydride solution, and keeping at 95 ℃ for 0.5 hour;

eighthly, cooling the liquid to room temperature, centrifugally washing for 3-4 times, and drying the product obtained by centrifugation at 60 ℃ for 12 hours to obtain the Ru/Mg-Al-L- (-) -MA LDH composite catalyst.

Technical Field

The invention relates to a method for preparing cis-pinane by catalyzing alpha-pinene hydrogenation by using an organic acid intercalated hydrotalcite supported ruthenium catalyst, in particular to a novel method for preparing cis-pinane by catalyzing alpha-pinene hydrogenation with high selectivity by using a composite material of L-Malic acid (L- (-) -Malic acid) intercalated magnesium aluminum hydrotalcite (Mg-Al LDH) supported ruthenium metal nanoparticles as a catalyst, and belongs to the field of preparation and application of catalysts.

Background

Turpentine is a kind of natural aromatic essential oil obtained by distilling turpentine secreted by plants of Pinus of Pinaceae, belongs to one of terpenoid essential oils, and can be used as organic solvent and for preparing high-grade perfume. The main component of alpha-pinene can be subjected to different reactions such as selective hydrogenation, epoxidation or isomerization to generate various deep-processed products, and the alpha-pinene is an indispensable raw material in the fields of spices, foods, medicines and the like. Wherein, the hydrogenation product cis-pinane is an important intermediate for producing terpenoid spices such as linalool, citronellol, dihydromyrcene and the like. The trans-pinane has far lower activity than cis-pinane due to steric hindrance effect, and is easy to cause more by-products and difficult to purify products. At present, the annual output of turpentine oil all over the world is about 40 ten thousand tons, and China is one of main production places. However, because the processing technology is limited, the quality of the relevant chemical products such as pinane and the like is poorer than that of foreign products, so that the alpha-pinene is mostly directly exported in a raw material form, and the additional value is lower. Therefore, the research and the application of the alpha-pinene catalytic hydrogenation for preparing the high-purity cis-pinane have important scientific significance and economic value.

Pd/C and Raney-Ni catalysts commonly used for preparing cis-pinane by hydrogenating alpha-pinene have good catalytic activity, but have poor selectivity to the cis-pinane and are difficult to recycle (appl.Catal.A: Gen.,2009,356,216; CN 1262263A). To this end, researchers in this field have been working on developing stable catalysts with high cis-pinane selectivity (RSC adv.,6,81310; US 4018842; CN 104003831A; CN 105330505). Mainly classified into noble and non-noble catalysts (CN 106316747A; RSC adv, 6,54806; J)Ind.eng.chem.,26,333; CN 104001515A; CN 102125864B; forestry chemistry and industry, 2016, 92). Although the noble metal catalyst has good activity and mild reaction conditions, the noble metal catalyst is expensive, high in production cost and easy to leach and run off in the reaction process; the non-noble metal catalyst has low price and wide source, but has relatively harsh reaction conditions and poor activity. Especially, the homogeneous catalyst has good activity and is difficult to recycle. The composite material of the noble metal and the metal oxide can reduce the use amount of the noble metal and is beneficial to the interaction between two components, thereby showing the physicochemical property superior to that of a single material. Such as Al₂O₃The supported nano noble metal Ru catalyst shows better catalytic activity than Pd/C in alpha-pinene hydrogenation reaction (US 4018842; US 4310714). Therefore, the research and development of the noble metal and metal oxide composite material for the alpha-pinene hydrogenation reaction are expected to obtain the catalyst which is cheap, efficient, stable and easy to recycle.

Disclosure of Invention

The invention aims to solve the problems of complex preparation process, high production cost, low selectivity, difficult recovery and reuse and the like of catalysts such as noble metals and the like used in the reaction for preparing cis-pinane by catalytic hydrogenation of alpha-pinene, and provides a catalyst of L-malic acid intercalation magnalium hydrotalcite (Mg-Al-L- (-) -MA LDH) loaded ruthenium metal nanoparticles, which has the advantages of simple preparation process, low cost and easy recovery and reuse, and the L-malic acid intercalation magnalium hydrotalcite loaded ruthenium catalyst is used for catalyzing the hydrogenation of alpha-pinene to prepare cis-pinane to obtain the performance of synthesizing the cis-pinane by the high-selectivity catalytic hydrogenation of alpha-pinene.

The invention is realized by the following technical scheme.

A method for preparing cis-pinane through hydrogenation of L-malic acid intercalation magnalium hydrotalcite loaded ruthenium catalyst to catalyze alpha-pinene is disclosed, the mass ratio of ruthenium to L-malic acid intercalation magnalium hydrotalcite in a composite catalyst is 3-10: 100, the mass ratio of the L-malic acid intercalation magnalium hydrotalcite loaded ruthenium (Ru/Mg-Al-L- (-) -MA LDH) composite catalyst to the alpha-pinene is 0.1:100, the ruthenium and the L-malic acid intercalation magnalium hydrotalcite are mixed, the reaction temperature is 100-140 ℃, the hydrogen pressure is 2-4 MPa, the reaction is complete, the cis-pinane is prepared, the catalytic activity is high, the catalyst is environment-friendly, the post-treatment is simple, and the catalyst can be recycled.

The detailed steps are as follows:

adding 50g of alpha-pinene into a reaction kettle, adding 0.05g of prepared malic acid intercalation magnalium hydrotalcite loaded ruthenium (Ru/Mg-Al-L- (-) -MA LDH) composite catalyst according to the mass ratio of the catalyst to the alpha-pinene of 0.1:100, and sealing the reaction kettle;

replacing three to four times by using hydrogen under the gauge pressure of 2.5-3.5 MPa, detecting leakage, and confirming that the reaction kettle is well sealed;

and opening a hydrogen gas inlet valve, adjusting the pressure in the kettle to be 2-4 MPa, opening a temperature rise controller of the reaction kettle, reacting at 100-140 ℃, and reacting at a stirring speed of 500 r/min.

Specifically, the stirring speed is 500r/min, and the reaction time is 5 h.

An L-malic acid intercalation magnalium hydrotalcite supported ruthenium catalyst for synthesizing cis-pinane by alpha-pinene hydrogenation, wherein the mass ratio of ruthenium (Ru) to L-malic acid intercalation magnalium hydrotalcite (Mg-Al-L- (-) -MA LDH) is 3-10: 100.

More particularly, the L-malic acid intercalated magnesium aluminum hydrotalcite (Mg-Al-L- (-) -MA LDH) is prepared from Mg (NO)₃)₂·6H₂O、Al(NO₃)₃·9H₂The O-malic acid and the L-malic acid are mixed and reacted according to the molar ratio of 2:1: 1.

A preparation method of L-malic acid intercalation magnalium hydrotalcite loaded ruthenium catalyst for synthesizing cis-pinane by alpha-pinene hydrogenation comprises the step of adding Mg (NO) according to a molar ratio of 2:1₃)₂·6H₂O and Al (NO)₃)₃·9H₂Dissolving O in deionized water, and mixing the amount of substance with Al³⁺Dissolving equal L-malic acid in deionized water, slowly mixing the two solutions, adjusting the pH value of the mixed solution to be alkalescent by using a sodium hydroxide solution, standing, sealing in a reaction container, placing in a constant-temperature oven for a period of time, cooling to room temperature after reaction, and centrifuging, washing and drying the product to obtain L-malic acid intercalation magnalium hydrotalcite (Mg-Al-L- (-) -MA LDH); adding RuCl according to the mass ratio of Ru to L-malic acid intercalated magnesium-aluminum hydrotalcite (Mg-Al-L- (-) -MA LDH) of 1-10: 100₃Standing at normal temperature for reaction for a period of time, and then risingAnd (3) adding a proper amount of sodium borohydride solution, cooling to room temperature after reaction, centrifuging, washing and drying to obtain the malic acid intercalation magnalium hydrotalcite loaded ruthenium (Ru/Mg-Al-L- (-) -MA LDH) composite catalyst.

More specifically, a preparation method of an L-malic acid intercalation magnalium hydrotalcite supported ruthenium catalyst for synthesizing cis-pinane by alpha-pinene hydrogenation comprises the following steps:

weighing 0.02mol of Mg (NO)₃)₂·6H₂O and 0.01mol of Al (NO)₃)₃·9H₂Dissolving O in 30mL of deionized water to obtain solution A, weighing 0.01mol of L-malic acid, and dissolving in 30mL of deionized water to obtain solution B;

dropping A into B, dropping 1mol/L sodium hydroxide solution (about 100mL) at the same time, adjusting the pH value to about 10.5 to obtain suspension, standing for 1h, placing the suspension into a reaction kettle, sealing by using a stainless steel jacket, and keeping for 6h in a constant-temperature oven at 150 ℃;

③ after the reaction is finished, the reaction kettle is naturally cooled to room temperature, the product is centrifuged and washed by deionized water until the pH value is equal to 7, and is dried for 12 hours at 80 ℃ to obtain Mg-Al-L- (-) -MA LDH.

Weighing 0.1g of Mg-Al-L- (-) -MA LDH obtained from the third step, adding into a conical flask, adding 250mL of deionized water into the conical flask, and performing ultrasonic treatment for 1 h;

fifthly, adding Na into the conical flask after the ultrasonic treatment is finished₂CO₃Adjusting the pH value of the solution in the conical flask to be 9-10;

sixthly, heating to 35 ℃, and adding 0.01-0.1 mmol of RuCl according to the mass ratio of Ru to Mg-Al-L- (-) -MA LDH of 1-10: 100₃Keeping the temperature at 35 ℃ for 3 h;

seventhly, after keeping at 35 ℃ for 3 hours, heating to 95 ℃, adding 0.2-2 mL of 300mM sodium borohydride solution, and keeping at 95 ℃ for 0.5 hour;

eighthly, cooling the liquid to room temperature, centrifugally washing for 3-4 times, and drying the product obtained by centrifugation at 60 ℃ for 12 hours to obtain the Ru/Mg-Al-L- (-) -MA LDH composite catalyst.

The Ru/Mg-Al-L- (-) -MA LDH composite catalyst adopted by the invention belongs to a heterogeneous catalyst, has a simple preparation process and easy recovery, can efficiently catalyze alpha-pinene to synthesize cis-pinane by hydrogenation at a low temperature, is heated and stirred for 5 hours at 120 ℃, and is filled with 3.0MPa hydrogen, the conversion rate of the Ru/Mg-Al-L- (-) -MA LDH (wherein the mass ratio of Ru to Mg-Al-L- (-) -MA LDH is 5:100) for catalyzing the alpha-pinene hydrogenation reaction is 100.00 percent, and the selectivity of the cis-pinane is 97.74 percent, which is superior to that of the similar heterogeneous catalysts.

Drawings

FIG. 1 is an XRD pattern of Mg-Al-L- (-) -MA LDH synthesized by the same procedure (r) -c) of example 1-3.

Detailed Description

The process of the present invention is further illustrated by the following examples, which are not intended to limit the invention.

Preparation of Ru/Mg-Al-L- (-) -MA LDH composite catalyst

Example 1 Ru/Mg-Al-L- (-) -MA LDH composite catalyst with a Ru/Mg-Al-L- (-) -MA LDH mass ratio of 1:100

Weighing 0.02mol of Mg (NO)₃)₂·6H₂O and 0.01mol of Al (NO)₃)₃·9H₂Dissolving O in 30mL of deionized water to obtain solution A, weighing 0.01mol of L-malic acid, and dissolving in 30mL of deionized water to obtain solution B;

dropping A into B, dropping 1mol/L sodium hydroxide solution (about 100mL) at the same time, adjusting the pH value to about 10.5 to obtain suspension, standing for 1h, placing the suspension into a reaction kettle, sealing by using a stainless steel jacket, and keeping for 6h in a constant-temperature oven at 150 ℃;

③ after the reaction is finished, the reaction kettle is naturally cooled to room temperature, the product is centrifuged and washed by deionized water until the pH value is equal to 7, and is dried for 12 hours at 80 ℃ to obtain Mg-Al-L- (-) -MA LDH.

Weighing 0.1g of Mg-Al-L- (-) -MA LDH obtained in the third step, adding into a conical flask, adding 250mL of deionized water, and performing ultrasonic treatment for 1 h;

fifthly, adding Na into the conical flask after the ultrasonic treatment is finished₂CO₃Adjusting the pH value in the conical flask to 9-10;

sixthly, heating to 35 ℃, and adding 0.01mmol RuCl according to the mass ratio of Ru to Mg-Al-L- (-) -MA LDH of 1:100₃Keeping the temperature at 35 ℃ for 3 h;

seventhly, after keeping the temperature at 35 ℃ for 3 hours, heating the mixture to 95 ℃, adding 0.2mL of 300mM sodium borohydride solution, and keeping the mixture at 95 ℃ for 0.5 hour;

eighthly, cooling the liquid to room temperature, centrifugally washing for 3-4 times, and drying the product obtained by centrifugation at 60 ℃ for 12 hours to obtain the Ru/Mg-Al-L- (-) -MA LDH composite catalyst.

Example 2 Ru/Mg-Al-L- (-) -MA LDH composite catalyst with a Ru/Mg-Al-L- (-) -MA LDH mass ratio of 3:100

Weighing 0.02mol of Mg (NO)₃)₂·6H₂O and 0.01mol of Al (NO)₃)₃·9H₂Dissolving O in 30mL of deionized water to obtain solution A, weighing 0.01mol of L-malic acid, and dissolving in 30mL of deionized water to obtain solution B;

dropping A into B, dropping 1mol/L sodium hydroxide solution (about 100mL) at the same time, adjusting the pH value to about 10.5 to obtain suspension, standing for 1h, placing the suspension into a reaction kettle, sealing by using a stainless steel jacket, and keeping for 6h in a constant-temperature oven at 150 ℃;

③ after the reaction is finished, the reaction kettle is naturally cooled to room temperature, the product is centrifuged and washed by deionized water until the pH value is equal to 7, and is dried for 12 hours at 80 ℃ to obtain Mg-Al-L- (-) -MA LDH.

Weighing 0.1g of Mg-Al-L- (-) -MA LDH obtained in the third step, adding into a conical flask, adding 250mL of deionized water, and performing ultrasonic treatment for 1 h;

fifthly, adding Na into the conical flask after the ultrasonic treatment is finished₂CO₃Adjusting the pH value in the conical flask to 9-10;

sixthly, heating to 35 ℃, and adding 0.03mmol of RuCl according to the mass ratio of 3:100 of Ru to Mg-Al-L- (-) -MA LDH₃Keeping the temperature at 35 ℃ for 3 h;

seventhly, after keeping at 35 ℃ for 3 hours, heating to 95 ℃, adding 1mL of 300mM sodium borohydride solution, and keeping at 95 ℃ for 0.5 hour;

eighthly, cooling the liquid to room temperature, centrifuging and washing for 4 times, and drying the product obtained by centrifuging at 60 ℃ for 12 hours to obtain the Ru/Mg-Al-L- (-) -MA LDH composite catalyst.

Example 3 Ru/Mg-Al-L- (-) -MA LDH composite catalyst with a Ru/Mg-Al-L- (-) -MA LDH mass ratio of 5:100

Weighing 0.02mol of Mg (NO)₃)₂·6H₂O and 0.01mol of Al (NO)₃)₃·9H₂Dissolving O in 30mL of deionized water to obtain solution A, weighing 0.01mol of L-malic acid, and dissolving in 30mL of deionized water to obtain solution B;

dropping A into B, dropping 1mol/L sodium hydroxide solution (about 100mL) at the same time, adjusting the pH value to about 10.5 to obtain suspension, standing for 1h, placing the suspension into a reaction kettle, sealing by using a stainless steel jacket, and keeping for 6h in a constant-temperature oven at 150 ℃;

③ after the reaction is finished, the reaction kettle is naturally cooled to room temperature, the product is centrifuged and washed by deionized water until the pH value is equal to 7, and is dried for 12 hours at 80 ℃ to obtain Mg-Al-L- (-) -MA LDH.

Weighing 0.1g of Mg-Al-L- (-) -MA LDH obtained in the third step, adding into a conical flask, adding 250mL of deionized water, and performing ultrasonic treatment for 1 h;

fifthly, adding Na into the conical flask after the ultrasonic treatment is finished₂CO₃Adjusting the pH value in the conical flask to 9-10;

sixthly, heating to 35 ℃, and adding 0.05mmol of RuCl according to the mass ratio of 5:100 of Ru to Mg-Al-L- (-) -MA LDH₃Keeping the temperature at 35 ℃ for 3 h;

seventhly, after keeping at 35 ℃ for 3 hours, heating to 95 ℃, adding 1mL of 300mM sodium borohydride solution, and keeping at 95 ℃ for 0.5 hour;

eighthly, cooling the liquid to room temperature, centrifuging and washing for 4 times, and drying the product obtained by centrifuging at 60 ℃ for 12 hours to obtain the Ru/Mg-Al-L- (-) -MA LDH composite catalyst.

Example 4 Ru/Mg-Al-L- (-) -MA LDH composite catalyst with a mass ratio of Ru to Mg-Al-L- (-) -MA LDH of 10:100

Weighing 0.02mol of Mg (NO)₃)₂·6H₂O and 0.01mol of Al (NO)₃)₃·9H₂Dissolving O in 30mL deionized water to obtain solution A, weighing 0.01mol L-malic acid, and dissolving in 30mL deionized waterWater to obtain solution B;

dropping A into B, dropping 1mol/L sodium hydroxide solution (about 100mL) at the same time, adjusting the pH value to about 10.5 to obtain suspension, standing for 1h, placing the suspension into a reaction kettle, sealing by using a stainless steel jacket, and keeping for 6h in a constant-temperature oven at 150 ℃;

③ after the reaction is finished, the reaction kettle is naturally cooled to room temperature, the product is centrifuged and washed by deionized water until the pH value is equal to 7, and is dried for 12 hours at 80 ℃ to obtain Mg-Al-L- (-) -MA LDH.

Weighing 0.1g of Mg-Al-L- (-) -MA LDH obtained in the third step, adding into a conical flask, adding 250mL of deionized water, and performing ultrasonic treatment for 1 h;

fifthly, adding Na into the conical flask after the ultrasonic treatment is finished₂CO₃Adjusting the pH value in the conical flask to 9-10;

sixthly, heating to 35 ℃, and adding 0.1mmol of RuCl according to the mass ratio of 10:100 of Ru to Mg-Al-L- (-) -MA LDH₃Keeping the temperature at 35 ℃ for 3 h;

seventhly, after keeping the temperature at 35 ℃ for 3 hours, heating the mixture to 95 ℃, adding 2mL of 300mM sodium borohydride solution, and keeping the mixture at 95 ℃ for 0.5 hour;

eighthly, cooling the liquid to room temperature, centrifuging and washing for 3 times, and drying the product obtained by centrifuging at 60 ℃ for 15 hours to obtain the Ru/Mg-Al-L- (-) -MA LDH composite catalyst.

Synthesis of cis-pinane by selective hydrogenation of alpha-pinene

Example 5

According to the mass ratio of the catalyst to the alpha-pinene of 0.1:100, 0.05g of Ru/Mg-Al-L- (-) -MA LDH (wherein the mass ratio of Ru to Mg-Al-L- (-) -MA LDH is 3:100) and 50g of alpha-pinene are added into a polytetrafluoroethylene reaction kettle, the air in the kettle is replaced by hydrogen for 4 times, then 3.0MPa hydrogen is filled, the mixture is heated and stirred for 5 hours at the temperature of 120 ℃, and the mixture is kept stand and cooled to the room temperature. The conversion rate of alpha-pinene is 100.00%, and the selectivity of cis-pinane is 97.64%.

Example 6

According to the mass ratio of the catalyst to the alpha-pinene of 0.1:100, 0.05g of Ru/Mg-Al-L- (-) -MA LDH (wherein the mass ratio of Ru to Mg-Al-L- (-) -MA LDH is 5:100) and 50g of alpha-pinene are added into a polytetrafluoroethylene reaction kettle, the air in the kettle is replaced by hydrogen for 4 times, then 3.0MPa hydrogen is filled, the mixture is heated and stirred for 5 hours at the temperature of 100 ℃, and the mixture is kept stand and cooled to the room temperature. The conversion of alpha-pinene was 96.61% and the selectivity to cis-pinane was 97.33%.

Example 7

According to the mass ratio of the catalyst to the alpha-pinene of 0.1:100, 0.05g of Ru/Mg-Al-L- (-) -MA LDH (wherein the mass ratio of Ru to Mg-Al-L- (-) -MA LDH is 5:100) and 50g of alpha-pinene are added into a polytetrafluoroethylene reaction kettle, the air in the kettle is replaced by hydrogen for 4 times, then 2.0MPa hydrogen is filled, the mixture is heated and stirred for 5 hours at the temperature of 120 ℃, and the mixture is kept stand and cooled to the room temperature. The conversion of alpha-pinene was 100.00% and the selectivity to cis-pinane was 96.74%.

Example 8

According to the mass ratio of the catalyst to the alpha-pinene of 0.1:100, 0.05g of Ru/Mg-Al-L- (-) -MA LDH (wherein the mass ratio of Ru to Mg-Al-L- (-) -MA LDH is 5:100) and 50g of alpha-pinene are added into a polytetrafluoroethylene reaction kettle, the air in the kettle is replaced by hydrogen for 4 times, then 3.0MPa hydrogen is filled, the mixture is heated and stirred for 5 hours at the temperature of 120 ℃, and the mixture is kept stand and cooled to the room temperature. The conversion of alpha-pinene is 100.00% and the selectivity of cis-pinane is 97.74%.

Example 9

According to the mass ratio of the catalyst to the alpha-pinene of 0.1:100, 0.05g of Ru/Mg-Al-L- (-) -MA LDH (wherein the mass ratio of Ru to Mg-Al-L- (-) -MA LDH is 5:100) and 50g of alpha-pinene are added into a polytetrafluoroethylene reaction kettle, 4 times of air in the kettle is replaced by hydrogen, 4.0MPa of hydrogen is filled, the mixture is heated and stirred at 120 ℃ for 5 hours, and the mixture is kept stand and cooled to room temperature. The conversion rate of alpha-pinene is 100.00%, and the selectivity of cis-pinane is 97.36%.

Example 10

According to the mass ratio of the catalyst to the alpha-pinene of 0.1:100, 0.05g of Ru/Mg-Al-L- (-) -MA LDH (wherein the mass ratio of Ru to Mg-Al-L- (-) -MA LDH is 5:100) and 50g of alpha-pinene are added into a polytetrafluoroethylene reaction kettle, the air in the kettle is replaced by hydrogen for 4 times, then 3.0MPa hydrogen is filled, the mixture is heated and stirred for 5 hours at the temperature of 140 ℃, and the mixture is kept stand and cooled to the room temperature. The conversion of alpha-pinene was 100.00% and the selectivity to cis-pinane was 94.97%.

Example 11

According to the mass ratio of the catalyst to the alpha-pinene of 0.1:100, 0.05g of Ru/Mg-Al-L- (-) -MA LDH (wherein the mass ratio of Ru to Mg-Al-L- (-) -MA LDH is 10:100) and 50g of alpha-pinene are added into a polytetrafluoroethylene reaction kettle, the air in the kettle is replaced by hydrogen for 4 times, then 3.0MPa hydrogen is filled, the mixture is heated and stirred for 5 hours at the temperature of 120 ℃, and the mixture is kept stand and cooled to the room temperature. The conversion of alpha-pinene was 100.00% and the selectivity to cis-pinane was 96.80%.

Comparative example 1

According to the mass ratio of the catalyst to the alpha-pinene of 0.1:100, 0.05g of Ru/Mg-Al-L- (-) -MA LDH (wherein the mass ratio of Ru to Mg-Al-L- (-) -MA LDH is 1:100) and 50g of alpha-pinene are added into a polytetrafluoroethylene reaction kettle, the air in the kettle is replaced by hydrogen for 4 times, then 3.0MPa hydrogen is filled, the mixture is heated and stirred for 5 hours at the temperature of 120 ℃, and the mixture is kept stand and cooled to the room temperature. The conversion of alpha-pinene was 2.54% and the selectivity to cis-pinane was 0%.

Comparative example 2

According to the mass ratio of the catalyst to the alpha-pinene of 0.1:100, 0.05g of Ru/Mg-Al-L- (-) -MA LDH (wherein the mass ratio of Ru to Mg-Al-L- (-) -MA LDH is 5:100) and 50g of alpha-pinene are added into a polytetrafluoroethylene reaction kettle, the air in the kettle is replaced by hydrogen for 4 times, then 3.0MPa hydrogen is filled, the mixture is heated and stirred for 5 hours at the temperature of 90 ℃, and the mixture is kept stand and cooled to the room temperature. The conversion of alpha-pinene was 43.56% and the selectivity to cis-pinane was 96.28%.

Comparative example 3

According to the mass ratio of the catalyst to the alpha-pinene of 0.1:100, 0.05g of Ru/Mg-Al-L- (-) -MA LDH (wherein the mass ratio of Ru to Mg-Al-L- (-) -MA LDH is 5:100) and 50g of alpha-pinene are added into a polytetrafluoroethylene reaction kettle, the air in the kettle is replaced by hydrogen for 4 times, then 1.0MPa hydrogen is filled, the mixture is heated and stirred for 5 hours at the temperature of 120 ℃, and the mixture is kept stand and cooled to the room temperature. The conversion of alpha-pinene was 31.08% and the selectivity to cis-pinane was 94.43%.

Comparative example 4

Weighing 0.02mol of Mg (NO)₃)₂·6H₂O and 0.01mol of Al (NO)₃)₃·9H₂Dissolving O in 30mL of deionized water to obtain solution A; dropwise adding 1mol/L sodium hydroxide solution into AAdjusting pH to about 10.5 to obtain suspension, standing for 1h, placing the suspension in a reaction kettle, sealing with a stainless steel jacket, and keeping in a constant temperature oven at 150 deg.C for 6 h; after the reaction is finished, the reaction kettle is naturally cooled to room temperature, the product is centrifuged and washed by deionized water until the pH value is equal to 7, the product is dried for 12 hours at 80 ℃ to obtain Mg-Al LDH, and the Ru/Mg-Al LDH catalyst is prepared according to the mass ratio of 5:100 of Ru to Mg-Al LDH.

Adding 0.05g of Ru/Mg-Al LDH (wherein the mass ratio of Ru to Mg-Al LDH is 5:100) and 50g of alpha-pinene into a polytetrafluoroethylene reaction kettle according to the mass ratio of the catalyst to the alpha-pinene of 0.1:100, replacing air in the kettle with hydrogen for 4 times, then filling 3.0MPa hydrogen, heating and stirring at 120 ℃ for 5 hours, standing and cooling to room temperature. The conversion of alpha-pinene was 5.43% and the selectivity of cis-pinane was 92.99%.

Comparative example 5

Weighing 0.02mol of Mg (NO)₃)₂·6H₂O and 0.01mol of Al (NO)₃)₃·9H₂Dissolving O in 30mL of deionized water to obtain solution A; dropwise adding 1mol/L sodium hydroxide solution (about 100mL) into the solution A, adjusting the pH value to about 10.5 to obtain a suspension, standing for 1h, placing the suspension into a reaction kettle, sealing by using a stainless steel jacket, and keeping for 6h in a constant-temperature oven at 150 ℃; after the reaction is finished, the reaction kettle is naturally cooled to room temperature, the product is centrifuged and washed by deionized water until the pH value is equal to 7, and the product is dried for 12 hours at 80 ℃ to obtain Mg-Al LDH.

Adding 0.05g of Mg-Al LDH and 50g of alpha-pinene into a polytetrafluoroethylene reaction kettle according to the mass ratio of the catalyst to the alpha-pinene of 0.1:100, replacing air in the kettle with hydrogen for 4 times, then filling 3.0MPa hydrogen, heating and stirring for 5h at 120 ℃, standing and cooling to room temperature. The conversion of alpha-pinene was 2.57% and the selectivity to cis-pinane was 96.21%.

The above experiments show that when the mass ratio of Ru to Mg-Al-L- (-) -MA LDH in Ru/Mg-Al-L- (-) -MA LDH is 1:100, the conversion rate of alpha-pinene is 2.54%, the selectivity of cis-pinane is 0%, and the catalytic effect is poor. The conversion rate of alpha-pinene is 43.56% and the selectivity of cis-pinene is 96.28% at the catalytic reaction temperature of 90 ℃, and when 1.0MPa hydrogen is filled in the kettle, the conversion rate of alpha-pinene is 31.08% and the selectivity of cis-pinene is 94.43%. In a comprehensive way, experiments show that when the mass ratio of Ru to Mg-Al-L- (-) -MA LDH in Ru/Mg-Al-L- (-) -MA LDH is 3-10: 100, and the reaction temperature is 100-140 ℃, and the hydrogen in a kettle is 2-4 MPa, the catalytic effect is good, the selectivity is good, and the conversion rate is high.

The comparison of comparative examples 4 and 5 shows that the L-malic acid intercalation treatment improves the performance of the catalyst, so that the conversion rate of the composite catalyst to alpha-pinene is improved from 2.57-5.43% to 100.00% and the selectivity of cis-pinane is improved from 92.99-96.21% to 97.74% when the mass ratio of Ru to Mg-Al LDH is 5:100 at 120 ℃ and the hydrogen pressure in a kettle is 3 MPa. Experiments show that the catalyst for L-malic acid intercalation can more efficiently catalyze alpha-pinene to synthesize cis-pinane through hydrogenation.

The above-described embodiments are only preferred embodiments of the present invention, and are not intended to limit the present invention in any way, and other variations and modifications may be made without departing from the spirit of the invention as set forth in the claims.