A sterically hindered amine for natural gas purification and a synthesis method and application thereof

Abstract

The application discloses a kind of steric hindrance amine for natural gas purification and synthesis method, application, the structural formula of the steric hindrance amine is as shown below:Wherein, R 1 It is methyl or ethyl;R 2 It is methyl or ethyl;R 3 Optionally is isopropyl or tert-butyl;Synthesis route is as shown below:Wherein, catalyst is TiO2 Supported quaternary metal catalyst or molecular sieve supported Ni-Y-La metal catalyst.The steric hindrance amine of the application, under the synergies of methyl or ethyl, isopropyl or tert-butyl structure and electronic effect, can be well removed to hydrogen sulfide and organic sulfur, and R 3 Position isopropyl or tert-butyl can make amine molecule have stronger steric effect, so that it has better selectivity to carbon dioxide, compared with traditional steric hindrance amine TBEE has higher sulfide removal capacity and carbon dioxide retention capacity, suitable for deep removal of carbonyl sulfur and retention of carbon dioxide in purified gas.

Description

Technical Field

[0001] This invention relates to the field of natural gas purification technology, and more specifically, to a sterically hindered amine for natural gas purification, its synthesis method, and its application. Background Technology

[0002] Among natural gas purification technologies both domestically and internationally, the amine method is the most widely used method for desulfurization and decarbonization. However, these purification processes all have certain limitations and face significant compliance challenges under the new natural gas standard GB17820-2018. Against this backdrop, sterically hindered amines, with their highly efficient ability to remove organic sulfur, have been introduced into the field of natural gas desulfurization.

[0003] Steric hindered amines are novel organic amines that possess one or two substituent groups on the α-carbon atom adjacent to the nitrogen atom in their molecules, thereby generating a steric hindrance effect. They have been extensively studied due to their excellent ability to remove H2S and CO2. Currently, commonly used steric hindered amines for desulfurization of natural gas or refinery gas include tert-butylaminoethoxyethanol (TBEE), 2-amino-2-methyl-1-propanol (AMP), and 2-piperidineethanol (PE). Steric hindered amines can currently be used for deep decarbonization or selective removal of hydrogen sulfide under high and normal pressures. TBEE can selectively remove hydrogen sulfide, but its removal effect on organic sulfur is poor. AMP and PE can remove CO2, but lack selectivity and are also ineffective at removing organic sulfur. Therefore, the continuous development of new steric hindered amines and their application in the field of natural gas purification is of great value.

[0004] In view of the above, this application is hereby submitted. Summary of the Invention

[0005] To address the aforementioned problems, the present invention aims to provide a sterically hindered amine for natural gas purification, its synthesis method, and its application. The sterically hindered amine exhibits excellent removal effects on hydrogen sulfide and carbonyl sulfide. Furthermore, due to the steric hindrance effect of its large sterically hindered groups, the absorption rate of CO2 by the sterically hindered amine is significantly reduced, resulting in better selectivity compared to traditional sterically hindered amines.

[0006] This invention is achieved through the following technical solution:

[0007] A sterically hindered amine for natural gas purification, the structural formula of which is shown below:

[0008]

[0009] Among them, R 1 It is methyl or ethyl; R 2 It is methyl or ethyl; R 3It can be selected as either isopropyl or tert-butyl.

[0010] The sterically hindered amine of the present invention, through the synergistic effect of the structural and electronic effects of methyl or ethyl, isopropyl or tert-butyl groups, can effectively remove hydrogen sulfide and organic sulfur compounds, and R 3 The isopropyl or tert-butyl groups at the position enable the amine molecule to have a stronger steric hindrance effect, making it more selective for carbon dioxide. Compared with traditional sterically hindered amines (TBEE), it has a higher sulfide removal capacity and carbon dioxide retention capacity, making it suitable for deep removal of carbonyl sulfides while retaining carbon dioxide in the purified gas.

[0011] A method for synthesizing a sterically hindered amine for natural gas purification, the synthetic route is shown below:

[0012]

[0013] The catalyst is either a TiO2-supported quaternary metal catalyst or a molecular sieve-supported Ni-Y-La metal catalyst.

[0014] More preferably, the TiO2-supported quaternary metal catalyst comprises four metal elements: Pd, Mn, Al, and Fe, wherein the molar content of Pd is 1-5%, the molar content of Mn is 15-25%, the molar content of Al is 20-40%, and the molar content of Fe is 40-60%; and the molar content of Ni-Y-La metal catalyst supported on molecular sieve is 10-20%, the molar content of Y is 10-60%, and the molar content of La is 5-10%.

[0015] Further preferred embodiments include a TiO2-supported quaternary metal catalyst in which the molar ratio of the four metal elements Pd, Mn, Al, and Fe is 1:20:25:45; and a molecular sieve-supported Ni-Y-La metal catalyst in which the molar ratio of the three metal elements Ni, Y, and La is 3:2:1.

[0016] This invention provides two methods for synthesizing the sterically hindered amine, as follows:

[0017] 1. Synthesis of the sterically hindered amine molecule using a TiO2-supported quaternary metal catalyst.

[0018] The synthesis steps are as follows:

[0019] 1) First, add the TiO2-supported quaternary metal catalyst and the substrate into a protic solvent. The molar ratio of the TiO2-supported quaternary metal catalyst to the substrate is 1:100-200. React for 1-4 hours.

[0020] 2) Add 1 equivalent of inorganic base, and reflux at 60-90℃ for 2-8 hours;

[0021] 3) Filter the generated salt and catalyst, collect the filtrate, distill the filtrate at atmospheric pressure in an oil bath at 200℃ for about 3 hours, filter it again, collect the filtrate and distill it under reduced pressure to obtain the product, a sterically hindered amine.

[0022] Further preferred, the molar ratio of TiO2-supported quaternary metal catalyst to substrate is 1:120.

[0023] Further preferred, the reaction time in step 1) is 2 hours.

[0024] Further preferred, the reaction temperature in step 2) is 85°C.

[0025] In a further preferred embodiment, the reflux reaction in step 2) is carried out for 4 hours.

[0026] A further preferred protic solvent is isopropanol.

[0027] A further preferred inorganic base is sodium bicarbonate.

[0028] 2. Synthesis of the sterically hindered amine molecule using a Ni-Y-La metal catalyst supported on a molecular sieve.

[0029] The synthesis steps are as follows:

[0030] 1) First, add the molecular sieve-supported Ni-Y-La metal catalyst and substrate to a protic solvent. The molar ratio of the catalyst to the substrate is 1:50 to 200, and the reaction time is 4 to 12 hours.

[0031] 2) Add 1 equivalent of inorganic base, and reflux at 60-90℃ for 2-8 hours;

[0032] 3) Filter the generated salt and catalyst, collect the filtrate, distill the filtrate at atmospheric pressure in an oil bath at 200℃ for about 3 hours, filter it again, collect the filtrate and distill it under reduced pressure to obtain a sterically hindered amine.

[0033] More preferably, the molar ratio of the molecular sieve-supported Ni-Y-La metal catalyst to the substrate is 1:150.

[0034] Further preferred, the reaction time in step 1) is 5 hours.

[0035] Further preferred, the reaction temperature in step 2) is 85°C.

[0036] In a further preferred embodiment, the reflux reaction in step 2) is carried out for 5 hours.

[0037] A further preferred protic solvent is isopropanol.

[0038] A further preferred inorganic base is sodium bicarbonate.

[0039] The method for synthesizing sterically hindered amines in this invention uses the two supported catalysts mentioned above. Compared with traditional synthesis methods, this catalytic synthesis method has mild reaction conditions, low catalyst loading, and high catalytic efficiency.

[0040] The present invention further provides an application of sterically hindered amine in natural gas desulfurization.

[0041] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0042] 1. The sterically hindered amine for natural gas purification provided in this embodiment of the invention can simultaneously and effectively remove hydrogen sulfide and organic sulfur under the synergistic effect of the structure and electronic effects of methyl or ethyl, isopropyl or tert-butyl groups. Compared with the traditional sterically hindered amine TBEE, it has a better desulfurization effect and can improve the removal effect of organic sulfur.

[0043] 2. An embodiment of the present invention provides a sterically hindered amine for natural gas purification, R 3 The presence of isopropyl or tert-butyl groups can give amine molecules a stronger steric hindrance effect and better selectivity for carbon dioxide. Compared with traditional sterically hindered amines (TBEE), it has a higher sulfide removal capacity and carbon dioxide retention capacity. It is a high-efficiency sterically hindered amine suitable for deep removal of carbonyl sulfide and retention of carbon dioxide in purified gas.

[0044] 3. The sterically hindered amine synthesis method for natural gas purification provided in this embodiment of the invention uses a TiO2-supported quaternary metal catalyst or a molecular sieve-supported Ni-Y-La metal catalyst for catalytic synthesis reaction. Compared with traditional synthesis methods, this catalytic synthesis method has mild reaction conditions, low catalyst loading, and high catalytic efficiency.

[0045] 4. The application of a sterically hindered amine in natural gas desulfurization provided in this embodiment of the invention can deeply and efficiently remove carbonyl sulfur and hydrogen sulfide from natural gas, while retaining carbon dioxide in the purified gas. Detailed Implementation

[0046] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the embodiments. The illustrative embodiments and descriptions of this invention are only used to explain this invention and are not intended to limit this invention.

[0047] In the following description, numerous specific details are set forth in order to provide a thorough understanding of the invention. However, it will be apparent to those skilled in the art that these specific details are not necessary to practice the invention. In other embodiments, well-known structures, circuits, materials, or methods have not been specifically described in order to avoid obscuring the invention.

[0048] Throughout this specification, references to "an embodiment," "an example," or "an example" mean that a particular feature, structure, or characteristic described in connection with that embodiment or example is included in at least one embodiment of the present invention. Therefore, the phrases "an embodiment," "an example," "an example," or "an example" appearing in various places throughout the specification do not necessarily refer to the same embodiment or example. Furthermore, specific features, structures, or characteristics can be combined in one or more embodiments or examples in any suitable combination and / or sub-combination.

[0049] This invention provides a sterically hindered amine for natural gas purification, the structural formula of which is shown below:

[0050]

[0051] Among them, R 1 It is methyl or ethyl; R 2 It is methyl or ethyl; R 3 It can be selected as either isopropyl or tert-butyl.

[0052] The sterically hindered amine of the present invention, through the synergistic effect of the structural and electronic effects of methyl or ethyl, isopropyl or tert-butyl groups, can effectively remove hydrogen sulfide and organic sulfur compounds, and R 3 The isopropyl or tert-butyl groups at the position enable the amine molecule to have a stronger steric hindrance effect, making it more selective for carbon dioxide. Compared with traditional sterically hindered amines (TBEE), it has a higher sulfide removal capacity and carbon dioxide retention capacity, making it suitable for deep removal of carbonyl sulfides while retaining carbon dioxide in the purified gas.

[0053] This invention provides a method for synthesizing sterically hindered amines using a TiO2-supported quaternary metal catalyst. The synthetic route is shown below:

[0054]

[0055] The steps are as follows:

[0056] 1) First, add the TiO2-supported quaternary metal catalyst and the substrate into a protic solvent. The molar ratio of the TiO2-supported quaternary metal catalyst to the substrate is 1:100-200. React for 1-4 hours.

[0057] 2) Add 1 equivalent of inorganic base, and reflux at 60-90℃ for 2-8 hours;

[0058] 3) Filter the generated salt and catalyst, collect the filtrate, distill the filtrate at atmospheric pressure in an oil bath at 200℃ for about 3 hours, filter it again, collect the filtrate and distill it under reduced pressure to obtain the product, a sterically hindered amine.

[0059] The following detailed examples 1-3 illustrate the method for synthesizing sterically hindered amines using TiO2-supported quaternary metal catalysts.

[0060] Example 1

[0061] This invention provides a method for synthesizing a sterically hindered amine for natural gas purification, comprising the following steps:

[0062] 1) 2,3-Dimethylbut-2-amine (1 mol) and 2-chloroethanol (1 mol) and 50 mL of isopropanol were added to a 500 mL reactor, and then 8 mmol of a quaternary TiO2 supported metal catalyst with a Pd-Mn-Al-Fe molar ratio of 1:20:25:45 was added. The mixture was stirred at 25 °C (600 rpm) for 4 h.

[0063] 2) After the reaction is complete, pour the mixture into a single-necked flask, add 1 equivalent of sodium bicarbonate, and reflux at 85°C for 6 hours.

[0064] 3) The generated salt and catalyst were filtered, the filtrate was collected, and the filtrate was distilled at atmospheric pressure in an oil bath at 200℃ for 3 hours. After filtration again, the filtrate was collected and distilled under reduced pressure to obtain the product 2-((2,3-dimethylbut-2-yl)amino)ethane-1-ol, with a yield of 92%.

[0065] Example 2

[0066] This invention provides a method for synthesizing a sterically hindered amine for natural gas purification, comprising the following steps:

[0067] 1) 2,3-dimethylpentane-3-amine (1 mol) and 2-chloroethanol (1 mol) and 50 mL of isopropanol were added to a 500 mL reactor, and then 8 mmol of a quaternary TiO2 supported metal catalyst with a Pd-Mn-Al-Fe molar ratio of 1:20:25:45 was added. The mixture was stirred at 25 °C (600 rpm) for 4 h.

[0068] 2) After the reaction is complete, pour the mixture into a single-necked flask, add 1 equivalent of sodium bicarbonate, and reflux at 85°C for 6 hours.

[0069] 3) Filter the generated salt and catalyst, collect the filtrate, distill the filtrate at atmospheric pressure in an oil bath at 200℃ for about 3 hours, filter again, collect the filtrate and distill under reduced pressure to obtain the product 2-((2,3-dimethylpent-3-yl)amino)ethane-1-ol, with a yield of 90%.

[0070] Example 3

[0071] This invention provides a method for synthesizing a sterically hindered amine for natural gas purification, comprising the following steps:

[0072] 1) 2,2,3-trimethylpentane-3-amine (1 mol), 2-chloroethanol (1 mol), and 50 mL of isopropanol were added to a 500 mL reactor. Then, a quaternary TiO2 supported metal catalyst (8 mmol) with a Pd-Mn-Al-Fe molar ratio of 1:20:25:45 was added. The mixture was stirred at 25 °C (600 rpm) for 4 h.

[0073] 2) After the reaction is complete, pour the mixture into a single-necked flask, add 1 equivalent of sodium bicarbonate, and reflux at 85°C for 6 hours.

[0074] 3) The generated salt and catalyst were filtered, the filtrate was collected, and the filtrate was distilled at atmospheric pressure in an oil bath at 200℃ for about 3 hours. After filtration again, the filtrate was collected and distilled under reduced pressure to obtain the product 2-((2,2,3-trimethylpentan-3-yl)amino)-1-ethanol, with a yield of 87%.

[0075] This invention also provides a method for synthesizing sterically hindered amines using a Ni-Y-La metal catalyst supported on a molecular sieve, as shown in the following synthetic route:

[0076]

[0077] The steps are as follows:

[0078] 1) First, add the molecular sieve-supported Ni-Y-La metal catalyst and substrate to a protic solvent. The molar ratio of the catalyst to the substrate is 1:50 to 200, and the reaction time is 4 to 12 hours.

[0079] 2) Add 1 equivalent of inorganic base, and reflux at 60-90℃ for 2-8 hours;

[0080] 3) Filter the generated salt and catalyst, collect the filtrate, distill the filtrate at atmospheric pressure in an oil bath at 200℃ for about 3 hours, filter it again, collect the filtrate and distill it under reduced pressure to obtain a sterically hindered amine.

[0081] The following detailed examples 4-6 illustrate the method for synthesizing sterically hindered amines using a Ni-Y-La metal catalyst supported on a molecular sieve.

[0082] Example 4

[0083] This invention provides a method for synthesizing a sterically hindered amine for natural gas purification, comprising the following steps:

[0084] 1) 2,3-dimethylpentane-3-amine (1 mol) and 2-chloroethanol (1 mol) and 50 mL of isopropanol were added to a 500 mL reactor, and then Ni-Y-La metal catalyst (6.7 mmol) supported on molecular sieve with a Ni-Y-La molar ratio of 3:2:1 was added. The mixture was stirred at 25 °C (600 rpm) for 4 h.

[0085] 2) After the reaction is complete, pour the mixture into a single-necked flask, add 1 equivalent of sodium bicarbonate, and reflux at 85°C for 6 hours.

[0086] 3) Filter the generated salt and catalyst, collect the filtrate, distill the filtrate at atmospheric pressure in an oil bath at 200℃ for about 3 hours, filter again, collect the filtrate and distill under reduced pressure to obtain the product 2-((2,3-dimethylpent-3-yl)amino)ethane-1-ol, with a yield of 95%.

[0087] Example 5

[0088] This invention provides a method for synthesizing a sterically hindered amine for natural gas purification, comprising the following steps:

[0089] 1) 2,3,3-trimethylbut-2-amine (1 mol) and 2-chloroethanol (1 mol) and 50 mL of isopropanol were added to a 500 mL reactor, and then Ni-Y-La metal catalyst (6.7 mmol) supported on molecular sieve with a Ni-Y-La molar ratio of 3:2:1 was added. The mixture was stirred at 25 °C (600 rpm) for 4 h.

[0090] 2) After the reaction is complete, pour the mixture into a single-necked flask, add 1 equivalent of sodium bicarbonate, and reflux at 85°C for 6 hours.

[0091] 3) Filter the generated salt and catalyst, collect the filtrate, distill the filtrate at atmospheric pressure in an oil bath at 200℃ for about 3 hours, filter again, collect the filtrate and distill under reduced pressure to obtain the product 2-((2,3,3-trimethylbut-2-yl)amino)ethane-1-ol, with a yield of 94%.

[0092] Example 6

[0093] This invention provides a method for synthesizing a sterically hindered amine for natural gas purification, comprising the following steps:

[0094] 1) 2,4,4-trimethylpentane-2-amine (1 mol) and 2-chloroethanol (1 mol) and 50 mL of isopropanol were added to a 500 mL reactor, and then Ni-Y-La metal catalyst (6.7 mmol) supported on molecular sieve with a Ni-Y-La molar ratio of 3:2:1 was added. The mixture was stirred at 25 °C (600 rpm) for 4 h.

[0095] 2) After the reaction is complete, pour the mixture into a single-necked flask, add 1 equivalent of sodium bicarbonate, and reflux at 85°C for 6 hours.

[0096] 3) The generated salt and catalyst were filtered, the filtrate was collected, and the filtrate was distilled at atmospheric pressure in an oil bath at 200℃ for about 3 hours. After filtration again, the filtrate was collected and distilled under reduced pressure to obtain the product 2-((2,4,4-trimethylpentan-2-yl)amino)-1-ethanol, with a yield of 83%.

[0097] As can be seen from the above, the present invention uses TiO2-supported quaternary metal catalysts or molecular sieve-supported Ni-Y-La metal catalysts to catalyze the synthesis of sterically hindered amines. The reaction conditions are mild, the catalyst loading is low, the catalytic efficiency is high, and the product yield is high.

[0098] Example 7

[0099] This invention provides an application of a sterically hindered amine in natural gas desulfurization. The natural gas feedstock to be purified is passed through a conventional TBEE solution and an aqueous solution of the sterically hindered amine of this invention, respectively. The content of each component in the purified gas after treatment is then measured. The experimental data are shown in Table 1. The aqueous solution of the sterically hindered amine of this invention is preferably an aqueous solution of 2-((2,4,4-trimethylpentan-2-yl)amino)-1-ethanol prepared in Example 6. The structure of 2-((2,4,4-trimethylpentan-2-yl)amino)-1-ethanol is shown below:

[0100]

[0101] Table 1 Comparative experimental results of the sterically hindered amine aqueous solution of the present invention and the traditional solution for natural gas desulfurization.

[0102]

[0103]

[0104] As shown in Table 1, under the same feed gas composition and absorption pressure (6.0 MPa), the 40% aqueous solution of this invention exhibits better sulfide purification and CO2 retention capabilities than the TBEE solution. The purified gas treated with the 40% aqueous solution of this invention contains 0.99 mg / m³ of H₂S and carbonyl sulfide. 3 and 3.48 mg / m3 It is far lower than 2 mg / m³ after treatment with 40% TBEE aqueous solution. 3 and 12.12 mg / m 3 Meanwhile, the CO2 content in the purified gas after treatment with 40% of the present invention aqueous solution (1.60%) is significantly lower than the CO2 content after treatment with 40% TBEE aqueous solution (0.96%).

[0105] Furthermore, when the absorption pressure is reduced to 4 MPa and 2 MPa, the 40% aqueous solution of the present invention still shows a better sulfide purification capacity than the 40% TBEE aqueous solution.

[0106] In summary, the sterically hindered amine of the present invention can deeply and efficiently remove carbonyl sulfide and hydrogen sulfide from natural gas, while having a higher ability to retain carbon dioxide in the purified gas. It is a highly efficient sterically hindered amine suitable for deep removal of carbonyl sulfide and retention of carbon dioxide in the purified gas.

[0107] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for synthesizing a sterically hindered amine for natural gas purification, characterized in that, The synthesis route is shown below: ； Among them, R 1 It is methyl or ethyl; R 2 It is methyl or ethyl; R 3 The catalyst is isopropyl or tert-butyl; the catalyst is a TiO2-supported quaternary metal catalyst or a molecular sieve-supported Ni-Y-La metal catalyst. The TiO2-supported quaternary metal catalyst comprises four metal elements: Pd, Mn, Al, and Fe, wherein the molar content of Pd is 1-5%, the molar content of Mn is 15-25%, the molar content of Al is 20-40%, and the molar content of Fe is 40-60%. The molecular sieve-supported Ni-Y-La metal catalyst comprises Ni with a molar content of 10-20%, Y with a molar content of 10-60%, and La with a molar content of 5-10%.

2. The method for synthesizing a sterically hindered amine for natural gas purification according to claim 1, characterized in that, In TiO2-supported quaternary metal catalysts, the molar ratio of the four metal elements Pd, Mn, Al, and Fe is 1:20:25:45; in molecular sieve-supported Ni-Y-La metal catalysts, the molar ratio of the three metal elements Ni, Y, and La is 3:2:

1.

3. The method for synthesizing a sterically hindered amine for natural gas purification according to claim 1, characterized in that, The specific steps of the synthesis method are as follows: 1) First, add the catalyst and substrate to a protic solvent to react; 2) Add an inorganic base and heat to carry out a reflux reaction; 3) Filter the generated salt and catalyst, collect the filtrate, and obtain a sterically hindered amine by distillation and rectification.

4. The method for synthesizing a sterically hindered amine for natural gas purification according to claim 1, characterized in that, The molar ratio of TiO2-supported quaternary metal catalyst to substrate is 1:100~200; the molar ratio of molecular sieve-supported Ni-Y-La metal catalyst to substrate is 1:50~200.

5. The method for synthesizing a sterically hindered amine for natural gas purification according to claim 1, characterized in that, The molar ratio of TiO2-supported quaternary metal catalyst to substrate is 1:120; the molar ratio of molecular sieve-supported Ni-Y-La metal catalyst to substrate is 1:

150.

6. The method for synthesizing a sterically hindered amine for natural gas purification according to claim 3, characterized in that, Isopropanol is used as the protic solvent.

7. The method for synthesizing a sterically hindered amine for natural gas purification according to claim 3, characterized in that, Sodium bicarbonate is used as the inorganic base.

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