Bifunctional catalyst, preparation method thereof and method for adsorbing and catalyzing H2S

Abstract

The invention relates to the technical field of catalysts, and discloses a bifunctional catalyst which comprises a carrier and metal active components loaded on the carrier, the carrier is a modified 13X molecular sieve, and the metal active components are Fe2O3 and ZnO; wherein on the basis of the total weight of the catalyst, the content of Fe2O3 is 4-5 wt%, the content of ZnO is 2-2.5 wt%, and the specific surface active site density of the catalyst is 1000-1500 / m < 2 >. Wherein the metal active component interacts with hydroxyl on the modified 13X molecular sieve, so that the metal active component is fixed on a pore channel, the metal active component and the molecular sieve act together to achieve a better catalytic effect, and the density of active sites on the specific surface is increased by regulating and controlling the ratio and preparation conditions of the catalyst, so that the catalytic activity of the catalyst is improved. Therefore, the catalytic activity and selectivity of the catalyst are improved, the catalyst has a bifunctional adsorbent-catalyst which selectively adsorbs H2S and catalyzes H2S into elemental sulfur, and adsorption desulfurization, adsorbent regeneration and sulfur recovery are integrated.

Description

Technical Field

[0001] The present invention relates to the technical field of catalysts, and in particular to a bifunctional catalyst and a preparation method thereof, and an adsorption catalytic H 2 S's method. Background Art

[0002] Natural gas is an important clean energy source. Major countries attach great importance to the proportion of natural gas in the primary energy structure. The International Energy Agency (IEA) predicts that global natural gas consumption will continue to grow in the next five years. The huge natural gas consumption market and the continuous improvement of exploration technology have promoted the development of natural gas around the world. With the vigorous exploitation of natural gas, the remaining resources tend to be inferior, and many of them are sulfur-containing (mainly H 2 In fact, in order to obtain more natural gas and sulfur, Russia, France, Canada, the United States, Kazakhstan and other countries have started to develop high-sulfur natural gas very early.

[0003] Adsorption desulfurization is widely used in low-content H 2 S natural gas desulfurization, fine desulfurization or removal of organic sulfur and other process steps. If the natural gas H 2 The S adsorbent also has the ability to catalyze H 2 S into elemental sulfur, multiple adsorption towers can be used to simultaneously perform adsorption desulfurization of natural gas and remove H 2 The adsorption tower and sulfur recovery tower are operated alternately to realize the coupling process of adsorption-sulfur recovery. The two steps involved in this technology have a large number of industrial cases. They can not only meet the technical requirements of desulfurized natural gas, but also process H2O2 after desulfurization. 2 S deals with the problem that makes H 2 The quality of sulfur after S conversion can reach the industrial sulfur standard, but after the chemical reactions involved in the two steps are coupled together, the adsorption-catalyst with both absorption desulfurization and catalytic conversion is a new problem that needs to be solved. Therefore, after solving the new problem, the adsorption desulfurization-catalytic conversion sulfur recovery coupling technology is a competitive natural gas desulfurization treatment technology. Summary of the invention

[0004] The purpose of the present invention is to overcome the problem of poor catalyst effect of the prior art adsorption desulfurization-catalytic conversion sulfur recovery coupling technology, and to provide a bifunctional catalyst and a preparation method thereof and an adsorption catalytic H 2 S's method.

[0005] In order to achieve the above object, the present invention provides a bifunctional catalyst in the first aspect, wherein the catalyst comprises: a carrier and a metal active component supported on the carrier, wherein the carrier is a modified 13X molecular sieve, and the metal active component is Fe 2 O 3 and ZnO; wherein, based on the total weight of the catalyst, Fe 2 O 3 The content of ZnO is 4-5wt%, the content of ZnO is 2-2.5wt%, and the specific surface active site density of the catalyst is 1000-1500 / m 2 .

[0006] A second aspect of the present invention provides a method for preparing a bifunctional catalyst, comprising:

[0007] (1) adding 13X molecular sieve into an alkaline solution, ultrasonicating and drying to obtain a modified 13X molecular sieve;

[0008] (2) The zinc salt, the iron salt and the modified 13X molecular sieve are mixed, dried and calcined to prepare the bifunctional catalyst.

[0009] The third aspect of the present invention provides a bifunctional catalyst prepared by the preparation method.

[0010] A fourth aspect of the present invention provides an adsorption catalytic H 2 S method, wherein the method comprises: in SO 2 In the presence of gas and catalyst, 2 S raw natural gas is subjected to a desulfurization reaction, wherein the catalyst is the bifunctional catalyst.

[0011] Through the above technical scheme, the present invention provides a bifunctional catalyst, wherein the metal active component interacts with the hydroxyl group on the modified 13X molecular sieve, so that the metal active component is fixed on the pore, and the metal active component and the molecular sieve work together to have a good catalytic effect, and by regulating the ratio and preparation conditions of the catalyst, the density of active sites on the specific surface is increased, thereby improving the catalytic activity and selectivity of the catalyst, and by limiting the specific content of the metal active component, the acidity and alkalinity of the catalyst can be adjusted, and the catalyst has the selective adsorption of H 2 S, while catalyzing H 2 S is a dual-function adsorbent-catalyst for elemental sulfur, which realizes adsorption desulfurization, adsorbent regeneration and sulfur recovery in one. In terms of process: natural gas adsorption desulfurization and sulfur recovery are integrated, simplifying the traditional independent adsorption, regeneration, acid gas sulfur recovery multi-equipment combination process into a limited number of reactors, which is easy to operate, saves investment, reduces energy consumption, reduces floor space, and can be skid-mounted. DETAILED DESCRIPTION

[0012] The endpoints and any values ​​of the ranges disclosed in this article are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

[0013] The first aspect of the present invention provides a bifunctional catalyst, wherein the catalyst comprises: a carrier and a metal active component supported on the carrier, wherein the carrier is a modified 13X molecular sieve, and the metal active component is Fe 2 O 3 and ZnO; wherein, based on the total weight of the catalyst, Fe 2 O 3 The content of ZnO is 4-5wt%, the content of ZnO is 2-2.5wt%, and the specific surface active site density of the catalyst is 1000-1500 / m 2 .

[0014] In the present invention, the metal active component interacts with the hydroxyl group on the modified 13X molecular sieve, so that the metal active component is fixed on the pores. The metal active component and the molecular sieve work together to have a good catalytic effect. At the same time, by limiting the specific content of the metal active component, when Fe 2 O 3 When the content of ZnO is 4-5wt% and the content of ZnO is 2-2.5wt%, the acidity and alkalinity of the catalyst can be adjusted, and the obtained catalyst has the highest saturated sulfur capacity. The catalyst has the ability to selectively adsorb H 2 S, while catalyzing H 2 S is a dual-function adsorbent-catalyst for elemental sulfur, which realizes adsorption desulfurization, adsorbent regeneration and sulfur recovery in one.

[0015] In some specific embodiments of the present invention, the modified 13X molecular sieve has a porous structure and an adjustable pore size distribution. The modified 13X molecular sieve has a suitable pore size and pore structure, which is more conducive to the adsorption of H 2 S molecules have a good catalytic effect and can make the specific surface active site density of the catalyst 1000-1500 / m 2 .

[0016] In some specific embodiments of the present invention, the specific surface active site density of the catalyst is 1000-1500 / m 2, by regulating the catalyst ratio and preparation conditions, the density of active sites on the specific surface can be increased, thereby improving the catalytic activity and selectivity of the catalyst. This limitation can bring the following advantages: (1) Improving reaction rate and product selectivity: Increasing the active site density can increase the contact opportunity between the reactants and the catalyst, enhance the adsorption and reaction process, thereby accelerating the reaction rate and improving product selectivity. (2) Reducing the amount of catalyst used: High active site density means that less catalyst can achieve the same reaction effect, thereby reducing the catalyst cost. The specific surface active site density can be determined by nitrogen adsorption-desorption measurement (BET method) to measure the specific surface area and pore volume of the catalyst, and then calculate the specific surface active site density. The specific surface active site density is calculated by correlating the specific surface area with the number of active sites in the catalyst.

[0017] In some specific embodiments of the present invention, the silicon-aluminum ratio of the modified 13X molecular sieve is 2-5: 1. The silicon-aluminum ratio refers to the molar ratio of silicon to aluminum in the modified 13X molecular sieve. By adjusting the silicon-aluminum ratio of the modified 13X molecular sieve within this range, the chemical properties and pore structure of the molecular sieve can be changed, thereby improving the adsorption and catalytic performance of the catalyst.

[0018] In some specific embodiments of the present invention, the average particle size of the catalyst is 0.3-0.5 mm. Smaller particle size can increase the contact area between the catalyst and the reactant and improve the adsorption effect. However, too small particles may cause the adsorption rate to drop rapidly after penetration. Therefore, the average particle size of the modified 13X molecular sieve used in the present invention is 0.3-0.5 mm, the catalyst adsorption effect is the best, and the best adsorption performance can be achieved.

[0019] In some specific embodiments of the present invention, the specific surface area of ​​the catalyst is 300-500m 2 / g. This limitation can bring the following advantages: (1) The catalyst of the present invention has a higher specific surface area, which can provide more active surface area, increase the contact area between the catalyst and the reactant, and thus promote the improvement of the reaction rate. More active surface area provides more catalytic active sites, which can make the specific surface active site density of the catalyst be 1000-1500 / m 2, which increases the catalyst's ability to adsorb and convert reactants, thereby effectively improving the catalyst's catalytic activity, achieving higher reaction conversion rates and product yields, thereby improving resource utilization efficiency and reducing catalyst waste. (2) Improved reaction selectivity: The catalyst's specific surface active site density plays a key role in the diffusion and transfer of reactant molecules. An appropriate specific surface active site density can achieve a uniform distribution of reactant molecules on the catalyst surface and reduce non-uniform reactions caused by local concentration changes. This helps to improve the selectivity of the reaction, reduce the occurrence of side reactions, and thus improve the purity and quality of the product. (3) Reaction kinetics control: The regulation of specific surface area can affect the adsorption capacity of the catalyst surface and the diffusion rate of reactant molecules, thereby affecting the reaction kinetics process. By controlling the range of specific surface area, effective control and regulation of the reaction rate can be achieved, making the reaction process more controllable and stable.

[0020] In some specific embodiments of the present invention, the pore volume of the catalyst is 0.3-0.5 cm 3 / g. This limitation can bring the following advantages: (1) Effective diffusion path: The appropriate pore volume range can provide suitable pore size and pore structure, providing a good channel for the diffusion and transfer of reactant molecules. A larger pore volume can provide a wider pore size distribution, promote the entry and exit of larger molecules into and out of the catalyst, and facilitate the diffusion-limited reaction. (2) Enhanced catalytic activity: The increase in pore volume can increase the active surface area inside the catalyst and provide more catalytic active sites. These sites can provide more adsorption sites, enhance the interaction between reactant molecules and catalysts, and help the catalytic reaction. In addition, a larger pore volume can also provide a larger reaction space, reduce competitive adsorption between reactants, and improve the selectivity of the catalyst. (3) Restriction of reactant molecules: The appropriate pore volume range can restrict the movement of reactant molecules inside the catalyst and reduce the occurrence of side reactions. A smaller pore volume can restrict the entry of larger molecules, thereby reducing non-selective reactions with the catalyst surface. This helps to improve the selectivity of the reaction and improve the purity and quality of the product. (4) Dispersion of reaction heat: A larger pore volume can provide more channels and pores, enhancing the catalyst's ability to disperse reaction heat. The heat generated during the catalytic reaction can be more evenly dispersed inside the catalyst, avoiding the formation of local high-temperature areas, alleviating the hot spot effect, and helping to improve the stability and service life of the catalyst.

[0021] In some specific embodiments of the present invention, the pH value of the surface acidity and alkalinity of the modified 13X molecular sieve is 8-9.5. The modified 13X molecular sieve has a certain acidity and alkalinity, and the acidity and alkalinity of the catalyst surface can be adjusted by regulating the ratio of the modified 13X molecular sieve and the preparation conditions of the present invention. The effects and advantages of limiting the surface acidity and alkalinity include: (1) regulating the adsorption and dissociation of reactants: appropriate acidity and alkalinity can regulate the adsorption and dissociation characteristics of reactants on the catalyst surface, which is conducive to the reaction and the formation of transition states. (2) controlling the reaction pathway and product selectivity: different acidity and alkalinity conditions can guide different reaction pathways and affect the product selectivity of the reaction, thereby achieving the desired reaction process and product distribution. (3) stability and life: limiting the stability and service life of the catalyst is crucial to achieving long-term stable catalytic performance. Optimizing the catalyst ratio, carrier selection and surface modification methods can improve the stability of the catalyst and extend its service life. (4) Improving the long-term performance of the catalyst: a stable catalyst can maintain its catalytic activity and selectivity over a long period of time, reduce the frequency of catalyst deactivation and regeneration, and improve production efficiency and economy. (5) Reduce catalyst replacement and maintenance costs: Improved stability and lifespan can extend the service life of the catalyst and reduce the frequency and cost of replacement and maintenance. Surface acidity and alkalinity can be analyzed by Fourier transform infrared spectroscopy (FTIR) to measure the vibration frequency and intensity of specific molecules adsorbed on the catalyst surface.

[0022] In some specific embodiments of the present invention, by adjusting the silicon-aluminum ratio, average particle size, specific surface area and pore volume of the modified 13X molecular sieve, the modified 13X molecular sieve can provide a more optimized pore structure, specific surface area and adsorption performance, thereby enhancing the interaction between the catalyst and the reactant, and improving the catalytic activity, selectivity and stability of the catalyst. The modified 13X molecular sieve has a porous structure and an adjustable pore size distribution. Through reasonable synthesis and treatment methods, the presence of micropores and mesopores can be achieved, and their size and distribution can be adjusted. This porous structure and pore size distribution are conducive to increasing the surface area, adsorption capacity and transfer rate of the catalyst, thereby improving the catalytic performance of the catalyst.

[0023] A second aspect of the present invention provides a method for preparing a bifunctional catalyst, comprising:

[0024] (1) adding 13X molecular sieve into an alkaline solution, ultrasonicating and drying to obtain a modified 13X molecular sieve;

[0025] (2) The zinc salt, the iron salt and the modified 13X molecular sieve are mixed, dried and calcined to prepare the bifunctional catalyst.

[0026] In the present invention, the chemical properties of 13X molecular sieve are improved by impregnating with alkaline solution. -Will react with SiO in the molecular sieve 2 Reaction occurs, so that part of the SiO in the molecular sieve 2 Erosion, modified 13X molecular sieve has a high specific surface area and developed pore volume, which changes the original structural characteristics of the molecular sieve, thereby increasing the adsorption performance of the catalyst. Its surface chemical properties play an important role in the removal of hydrogen sulfide and improve the desulfurization effect.

[0027] In some specific embodiments of the present invention, the modified 13X molecular sieve has a silicon-aluminum ratio of 2-5:1, an average particle size of 0.3-0.5 mm, and a specific surface area of ​​300-500 m 2 / g, and the pore volume is 0.3-0.5cm3 / g.

[0028] In some specific embodiments of the present invention, the alkaline solution is selected from NaOH solution, KOH solution, NH 4 One or more of OH.

[0029] In some specific embodiments of the present invention, the zinc salt is selected from one or more of zinc nitrate and zinc chloride.

[0030] In some specific embodiments of the present invention, the iron salt is selected from one or more of ferric nitrate and ferric chloride.

[0031] In some specific embodiments of the present invention, in step (1), the ultrasonication time is 10-20 min, the drying temperature is 80-120° C., and the drying time is 2-4 h.

[0032] In some specific embodiments of the present invention, step (2) further comprises standing for 8-12 hours after the mixing.

[0033] In some specific embodiments of the present invention, in step (2), the drying temperature is 120-150° C., and the drying time is 3-6 hours.

[0034] In some specific embodiments of the present invention, in step (2), the calcination temperature is 300-500° C. and the calcination time is 2-4 hours. By controlling the calcination temperature and time, the pore structure and pore size distribution of the catalyst can be adjusted.

[0035] In some specific embodiments of the present invention, the zinc and iron salt solution contains 0.5-1 parts by weight of zinc salt and 1-2 parts by weight of iron salt relative to 5-10 parts by weight of 13X molecular sieve and 10-20 mL of 25 wt% alkaline solution.

[0036] The third aspect of the present invention provides a bifunctional catalyst prepared by the preparation method.

[0037] A fourth aspect of the present invention provides an adsorption catalytic H 2 S method, wherein the method comprises: in SO 2 In the presence of gas and catalyst, 2 S raw natural gas is subjected to a desulfurization reaction, wherein the catalyst is the bifunctional catalyst.

[0038] In some specific embodiments of the present invention, the catalytic reaction temperature is 150-250° C., and the catalytic reaction pressure is 0.5-5 MPa.

[0039] In some specific embodiments of the present invention, n(H 2 S) / n(SO 2 ) is 1-3, preferably 2.

[0040] In some specific embodiments of the present invention, the air velocity is 200-500h -1 , the H in the crude natural gas 2 The volume fraction of S is 1.6-2%, where space velocity refers to the rate at which gas passes through the catalyst per unit time.

[0041] The present invention will be described in detail below through examples.

[0042] Specific surface active site density and specific surface area determination: Nitrogen adsorption-desorption measurement (BET method) can be used to determine the specific surface area and pore volume of the catalyst, and then calculate the specific surface active site density.

[0043] General steps for determining the specific surface active site density of a catalyst using the BET method:

[0044] (1) Preparation of catalyst samples: Catalyst samples are usually pre-treated at high temperature to remove any adsorbent. This is to ensure that the sample is in a dry state.

[0045] (2) Nitrogen adsorption: The dried catalyst sample is exposed to liquid nitrogen and then exposed to nitrogen gas so that the nitrogen gas is adsorbed onto the catalyst surface.

[0046] (3) Nitrogen desorption: The catalyst sample is gradually heated while monitoring the desorption of nitrogen. This can be used to determine the adsorption and desorption isotherms.

[0047] (4) Data analysis: The adsorption-desorption data were analyzed using methods such as the BET equation to calculate the specific surface area and specific surface active site density of the catalyst.

[0048] The specific surface active site density was calculated by relating the specific surface area to the number of active sites in the catalyst.

[0049] Surface acidity and alkalinity determination: Fourier transform infrared spectroscopy (FTIR) can analyze the acidity and alkalinity of the catalyst by measuring the vibration frequency and intensity of specific molecules adsorbed on the catalyst surface.

[0050] In the following examples and comparative examples, if no specific conditions are specified, the experiments were carried out under conventional conditions or conditions recommended by the manufacturer. The reagents or instruments used, if no manufacturer is specified, are all conventional products that can be obtained through commercial channels.

[0051] Example 1

[0052] (1) After grinding and sieving the 13X molecular sieve, a molecular sieve with an average particle size of 0.3-0.5 mm was selected and repeatedly washed in deionized water until the water was clear and free of suspended matter, and then immersed in deionized water for 4 hours, filtered and dried in a drying oven at 105° C. for 12 hours to obtain the pretreated 13X molecular sieve as is.

[0053] (2) The ground and sieved 13X molecular sieve was dried in a drying oven at 105° C. for 12 h, and then calcined in a muffle furnace at 500° C. for 3 h to obtain a pretreated 13X molecular sieve.

[0054] (3) The pretreated 13X molecular sieve was uniformly added into 15 ml of an alkaline solution with a concentration of 25 wt %, ultrasonically shaken for 30 min, left to stand for 1 hour, and then dried in a drying oven at 105° C. for 12 hours to prepare a modified 13X molecular sieve.

[0055] (4) Weigh different masses of zinc nitrate and iron nitrate, dissolve them completely in distilled water, and then add 20.0 g of modified 13X molecular sieve. Stir evenly and place for 24 hours, then bake at 120°C for several hours. 2 Under protection, it was placed in a muffle furnace at 350°C for calcination for 2 hours, and then cooled to obtain a bifunctional catalyst A1.

[0056] Wherein, based on the total weight of the catalyst, Fe 2 O 3 The content of is 4.5wt%, and the content of ZnO is 2.5wt%; wherein the silicon-aluminum ratio of the modified 13X molecular sieve is 3:1.

[0057] Example 2

[0058] (1) After grinding and sieving the 13X molecular sieve, a molecular sieve with an average particle size of 0.3-0.5 mm was selected and repeatedly washed in deionized water until the water was clear and free of suspended matter, and then immersed in deionized water for 4 hours, filtered and dried in a drying oven at 105° C. for 12 hours to obtain the pretreated 13X molecular sieve as is.

[0059] (2) The ground and sieved 13X molecular sieve was dried in a drying oven at 105° C. for 12 h, and then calcined in a muffle furnace at 500° C. for 3 h to obtain a pretreated 13X molecular sieve.

[0060] (3) The pretreated 13X molecular sieve was uniformly added to the alkaline solution in proportion, ultrasonically shaken for 30 minutes, left to stand for hours, and then dried in a drying oven at 105° C. for 12 hours to prepare a modified 13X molecular sieve.

[0061] (4) Weigh different masses of zinc nitrate and iron nitrate, dissolve them completely in distilled water, and then add 20.0 g of modified 13X molecular sieve. Stir evenly and place for 24 hours, then bake at 120°C for several hours. 2 Under protection, it was placed in a muffle furnace at 350°C for calcination for 2 h, and then cooled to obtain a bifunctional catalyst A2;

[0062] Based on the total weight of the catalyst, Fe 2 O 3 The content of is 4wt%, the content of ZnO is 3wt%, wherein the silicon-aluminum ratio of the modified 13X molecular sieve is 4:1.

[0063] Example 3

[0064] (1) After grinding and sieving the 13X molecular sieve, a molecular sieve with an average particle size of 0.3-0.5 mm was selected and repeatedly washed in deionized water until the water was clear and free of suspended matter, and then immersed in deionized water for 4 hours, filtered and dried in a drying oven at 105° C. for 12 hours to obtain the pretreated 13X molecular sieve as is.

[0065] (2) The ground and sieved 13X molecular sieve was dried in a drying oven at 105° C. for 12 h, and then calcined in a muffle furnace at 500° C. for 3 h to obtain a pretreated 13X molecular sieve.

[0066] (3) The pretreated 13X molecular sieve was uniformly added to the alkaline solution in proportion, ultrasonically shaken for 30 minutes, left to stand for hours, and then dried in a drying oven at 105° C. for 12 hours to prepare a modified 13X molecular sieve.

[0067] (4) Weigh different masses of zinc nitrate and iron nitrate, dissolve them completely in distilled water, and then add 20.0 g of modified 13X molecular sieve. Stir evenly and place for 24 hours, then bake at 120°C for several hours. 2 Under protection, it was placed in a muffle furnace at 350°C for calcination for 2 h, and then cooled to obtain a bifunctional catalyst A3;

[0068] Based on the total weight of the catalyst, Fe 2 O 3The content of is 5.0wt%, the content of ZnO is 2.0wt%, and the silicon-aluminum ratio of the modified 13X molecular sieve is 5:1.

[0069] Example 4

[0070] (1) After grinding and sieving the 13X molecular sieve, a molecular sieve with an average particle size of 0.4-0.6 mm was selected and repeatedly washed in deionized water until the water was clear and free of suspended matter, and then immersed in deionized water for 4 hours, filtered and dried in a drying oven at 105° C. for 12 hours to obtain the pretreated 13X molecular sieve as is.

[0071] (2) The ground and sieved 13X molecular sieve was dried in a drying oven at 105° C. for 12 h, and then calcined in a muffle furnace at 500° C. for 3 h to obtain a pretreated 13X molecular sieve.

[0072] (3) The pretreated 13X molecular sieve was uniformly added to the alkaline solution in proportion, ultrasonically shaken for 30 minutes, left to stand for hours, and then dried in a drying oven at 105° C. for 12 hours to prepare a modified 13X molecular sieve.

[0073] (4) Weigh different masses of zinc nitrate and iron nitrate, dissolve them completely in distilled water, and then add 20.0 g of modified 13X molecular sieve. Stir evenly and place for 24 hours, then bake at 120°C for several hours. 2 Under protection, it was placed in a muffle furnace at 350°C for calcination for 2 h, and then subjected to subsequent cooling treatment to obtain a bifunctional catalyst A4;

[0074] Wherein, based on the total weight of the catalyst, Fe 2 O 3 The content of is 4.5wt%, the content of ZnO is 2.5wt%, and the silicon-aluminum ratio of the modified 13X molecular sieve is 3:1.

[0075] Example 5

[0076] (1) After grinding and sieving the 13X molecular sieve, a molecular sieve with an average particle size of 0.2-0.4 mm was selected and repeatedly washed in deionized water until the water was clear and free of suspended matter, and then immersed in deionized water for 4 hours, filtered and dried in a drying oven at 105° C. for 12 hours to obtain the pretreated 13X molecular sieve as is.

[0077] (2) The ground and sieved 13X molecular sieve was dried in a drying oven at 105° C. for 12 h, and then calcined in a muffle furnace at 500° C. for 3 h to obtain a pretreated 13X molecular sieve.

[0078] (3) The pretreated 13X molecular sieve was uniformly added to the alkaline solution in proportion, ultrasonically shaken for 30 minutes, left to stand for hours, and then dried in a drying oven at 105° C. for 12 hours to prepare a modified 13X molecular sieve.

[0079] (4) Weigh different masses of zinc nitrate and iron nitrate, dissolve them completely in distilled water, and then add 20.0 g of modified 13X molecular sieve. Stir evenly and place for 24 hours, then bake at 120°C for several hours. 2 Under protection, it was placed in a muffle furnace at 350°C for calcination for 2h, and then cooled to obtain a bifunctional catalyst A5;

[0080] Wherein, based on the total weight of the catalyst, Fe 2 O 3 The content of is 4.5wt%, the content of ZnO is 2.5wt%, and the silicon-aluminum ratio of the modified 13X molecular sieve is 3:1.

[0081] Example 6

[0082] (1) After grinding and sieving the 13X molecular sieve, a molecular sieve with an average particle size of 0.5-0.7 mm was selected and repeatedly washed in deionized water until the water was clear and free of suspended matter, and then immersed in deionized water for 4 hours, filtered and dried in a drying oven at 105° C. for 12 hours to obtain the pretreated 13X molecular sieve as is.

[0083] (2) The ground and sieved 13X molecular sieve was dried in a drying oven at 105° C. for 12 h, and then calcined in a muffle furnace at 500° C. for 3 h to obtain a pretreated 13X molecular sieve.

[0084] (3) The pretreated 13X molecular sieve was uniformly added to the alkaline solution in proportion, ultrasonically shaken for 30 minutes, left to stand for hours, and then dried in a drying oven at 105° C. for 12 hours to prepare a modified 13X molecular sieve.

[0085] (4) Weigh different masses of zinc nitrate and iron nitrate, dissolve them completely in distilled water, and then add 20.0 g of modified 13X molecular sieve. Stir evenly and place for 24 hours, then bake at 120°C for several hours. 2 Under protection, it was placed in a muffle furnace at 350°C for calcination for 2 h, and then subjected to subsequent cooling treatment to obtain a bifunctional catalyst A6;

[0086] Wherein, based on the total weight of the catalyst, Fe 2 O 3 The content of is 4.5wt%, the content of ZnO is 2.5wt%, and the silicon-aluminum ratio of the modified 13X molecular sieve is 1:1.

[0087] Example 7

[0088] (1) After grinding and sieving the 13X molecular sieve, a molecular sieve with an average particle size of 0.3-0.5 mm was selected and repeatedly washed in deionized water until the water was clear and free of suspended matter, and then immersed in deionized water for 4 hours, filtered and dried in a drying oven at 105° C. for 12 hours to obtain the pretreated 13X molecular sieve as is.

[0089] (2) The ground and sieved 13X molecular sieve was dried in a drying oven at 105° C. for 12 h, and then calcined in a muffle furnace at 500° C. for 3 h to obtain a pretreated 13X molecular sieve.

[0090] (3) The pretreated 13X molecular sieve was uniformly added to the alkaline solution in proportion, ultrasonically shaken for 30 minutes, left to stand for hours, and then dried in a drying oven at 105° C. for 12 hours to prepare a modified 13X molecular sieve (silicon-aluminum ratio of 1:1).

[0091] (4) Weigh different masses of zinc nitrate and iron nitrate, dissolve them completely in distilled water, and then add 20.0 g of modified 13X molecular sieve. Stir evenly and place for 24 hours, then bake at 120°C for several hours. 2 Under protection, it was placed in a muffle furnace at 350°C for calcination for 2 h, and then cooled to obtain a bifunctional catalyst A7;

[0092] Based on the total weight of the catalyst, Fe 2 O 3 The content of is 4.5wt%, the content of ZnO is 2.5wt%, and the silicon-aluminum ratio of the modified 13X molecular sieve is 6:1.

[0093] Comparative Example 1

[0094] (1) After grinding and sieving the 10X molecular sieve, a molecular sieve with an average particle size of 0.3-0.5 mm was selected and repeatedly washed in deionized water until the water was clear and free of suspended matter, and then immersed in deionized water for 4 hours, filtered and dried in a drying oven at 105° C. for 12 hours to obtain the pretreated 13X molecular sieve as is.

[0095] (2) The ground and sieved 10X molecular sieve was dried in a drying oven at 105° C. for 12 h, and then calcined in a muffle furnace at 500° C. for 3 h to obtain a pretreated 10X molecular sieve.

[0096] (3) The pretreated 10X molecular sieve was uniformly added to the alkaline solution in proportion, ultrasonically shaken for 30 minutes, left to stand for hours, and then dried in a drying oven at 105° C. for 12 hours to prepare a modified 13X molecular sieve.

[0097] (4) Weigh different masses of zinc nitrate and iron nitrate, dissolve them completely in distilled water, and then add 20.0 g of modified 10X molecular sieve. Stir evenly and place for 24 hours, then bake at 120°C for several hours. 2 Under protection, the catalyst was placed in a muffle furnace at 350°C and calcined for 2 h, and then cooled to obtain catalyst B1;

[0098] Wherein, based on the total weight of the catalyst, Fe 2 O 3 The content of is 4.5wt%, the content of ZnO is 2.5wt%, wherein the silicon-aluminum ratio of the modified 10X molecular sieve is 3:1.

[0099] Comparative Example 2

[0100] (1) After grinding and sieving the 10X molecular sieve, select a molecular sieve with an average particle size of 0.3-0.5 mm and repeatedly wash it in deionized water until the water is clear and free of suspended matter, then immerse it in deionized water for 4 hours, filter it, and dry it in a drying oven at 105° C. for 12 hours to obtain the pretreated 10X molecular sieve as is.

[0101] (2) The ground and sieved 10X molecular sieve was dried in a drying oven at 105° C. for 12 h, and then calcined in a muffle furnace at 500° C. for 3 h to obtain a pretreated 10X molecular sieve.

[0102] (3) The pretreated 10X molecular sieve was uniformly added to the alkaline solution in proportion, ultrasonically shaken for 30 minutes, left to stand for hours, and then dried in a drying oven at 105° C. for 12 hours to prepare a modified 10X molecular sieve.

[0103] (4) Weigh different masses of zinc nitrate and iron nitrate, dissolve them completely in distilled water, and then add 20.0 g of modified 10X molecular sieve. Stir evenly and place for 24 hours, then bake at 120°C for several hours. 2 Under protection, it was placed in a muffle furnace at 350°C for calcination for 2 h, and then cooled to obtain a bifunctional catalyst B2;

[0104] Wherein, based on the total weight of the catalyst, Fe 2 O 3 The content of is 4.5wt%, the content of ZnO is 4wt%, and the silicon-aluminum ratio of the modified 10X molecular sieve is 3:1.

[0105] Comparative Example 3

[0106] (1) After grinding and sieving the 13X molecular sieve, a molecular sieve with an average particle size of 0.3-0.5 mm was selected and repeatedly washed in deionized water until the water was clear and free of suspended matter, and then immersed in deionized water for 4 hours, filtered and dried in a drying oven at 105° C. for 12 hours to obtain the pretreated 13X molecular sieve as is.

[0107] (2) The ground and sieved 13X molecular sieve was dried in a drying oven at 105° C. for 12 h, and then calcined in a muffle furnace at 500° C. for 3 h to obtain a pretreated 13X molecular sieve.

[0108] (3) The pretreated 13X molecular sieve was uniformly added to the alkaline solution in proportion, ultrasonically shaken for 30 minutes, left to stand for hours, and then dried in a drying oven at 105° C. for 12 hours to prepare a modified 13X molecular sieve.

[0109] (4) Weigh different masses of zinc nitrate and iron nitrate, dissolve them completely in distilled water, and then add 20.0 g of modified 13X molecular sieve. Stir evenly and place for 24 hours, then bake at 120°C for several hours. 2 Under protection, it was placed in a muffle furnace at 350°C for calcination for 2 h, and then cooled to obtain a bifunctional catalyst B3;

[0110] Wherein, based on the total weight of the catalyst, Fe 2 O 3 The content of is 6wt%, and the content of ZnO is 2.5wt%; wherein the silicon-aluminum ratio of the modified 13X molecular sieve is 3:1.

[0111] Test Example 1

[0112] The test methods for adsorbent performance are divided into static method and dynamic method. Since hydrogen sulfide is mixed with various gases in this experiment, hydrogen sulfide will be adsorbed by the adsorbent when passing through the adsorption bed. Therefore, detecting the hydrogen sulfide concentration at the fixed bed outlet is an important indicator for evaluating the adsorption effect of the adsorbent. When hydrogen sulfide is detected at the fixed bed outlet, it indicates that the desulfurizer has penetrated. Continue to detect until the outlet concentration reaches a certain concentration value and stop measuring. Plot the concentration of hydrogen sulfide in the outlet gas and time to obtain the adsorbent penetration curve.

[0113] Adsorbent desulfurization evaluation indicators include breakthrough time, breakthrough sulfur capacity, saturated sulfur capacity and hydrogen sulfide conversion rate.

[0114] Sulfur capacity is defined as the mass of hydrogen sulfide adsorbed by a unit mass of adsorbent, and the unit is generally mg / g. The sulfur capacity can be determined by calculation or by directly measuring the mass change of the adsorbent before and after adsorption. When other evaluation conditions remain unchanged, there is a corresponding relationship between the sulfur capacity of the adsorbent and time.

[0115] Breakthrough sulfur capacity: When the hydrogen sulfide concentration at the outlet of the adsorption bed reaches a certain index, the mass of hydrogen sulfide adsorbed by a unit mass of adsorbent is the breakthrough sulfur capacity. Considering the safety of desulfurization adsorbents in practical applications and the generally high requirements for desulfurization effects, this experiment defines the time when the hydrogen sulfide concentration at the outlet of the adsorption bed is 1ppm as the breakthrough time, and the sulfur capacity at this time is the breakthrough sulfur capacity. The calculation formula for breakthrough sulfur capacity is as follows:

[0116]

[0117] Where: q represents the breakthrough sulfur capacity of the adsorbent, in mg / g;

[0118] Q represents the gas flow rate, in mL / min;

[0119] T represents the penetration time, in min;

[0120] C0 represents the hydrogen sulfide concentration at the inlet of the adsorption bed, in mg / m 3 ;

[0121] CT represents the hydrogen sulfide concentration at the outlet of the adsorption bed, in mg / m 3 ;

[0122] m represents the mass of the adsorbent before desulfurization, in g.

[0123] When the hydrogen sulfide concentration at the outlet of the adsorption bed is 50% of the inlet concentration, the reaction stops. In this experiment, breakthrough sulfur capacity and breakthrough curve are used as important indicators to measure adsorption performance.

[0124] The adsorbent is loaded into the reactor, and the reactor is filled with the adsorbent bifunctional agent. The same reactor is in one of the three states of adsorption, regeneration, and cooling during continuous operation. The three states are switched cyclically to achieve continuous operation of natural gas desulfurization, sulfur recovery, and adsorbent regeneration. 2 The volume fraction of S is 1.6%, the rest is nitrogen, the test pressure is 0.5MPa, and the air velocity ratio is 450h -1 , the absorbent particle size is 0.4 mm, and the gas flow rate is 380 mL / min.

[0125] According to the above method, the sulfur capacity and sulfur recovery rate of the catalysts of the examples and comparative examples were tested. The results are shown in Table 1.

[0126] Table 1

[0127]

[0128]

[0129] Table 1 (continued)

[0130]

[0131]

[0132] It can be seen from the results in Table 1 that the present invention provides a catalyst system based on 13X molecular sieve, and the optimization and adjustability of catalyst performance can be achieved by adjusting parameters such as component content, physical properties and metal weight ratio.

[0133] The results of Examples 1-3 and 4-5 show that the performance of the catalyst can be affected by adjusting the pH value of the catalyst surface acidity and alkalinity. When the pH value of the catalyst surface acidity and alkalinity is 8-9.5, the catalyst has better specific surface active site density, sulfur capacity and sulfur recovery rate.

[0134] The results of Example 1 and Examples 6-7 show that the performance of the catalyst can be affected by adjusting the silicon-aluminum ratio of the modified 13X molecular sieve of the catalyst, and the modified 13X molecular sieve has a better catalytic effect when the silicon-aluminum ratio is 2-5:1.

[0135] The results of Example 1 and Comparative Example 1 show that the 13X molecular sieve of the present application has better effects than other molecular sieves. The results of Comparative Examples 2-3 verify the importance of the metal weight ratio adopted in Example 1. The metal weight ratio setting outside the scope of the present application will lead to poor catalytic performance and a significant reduction in the catalyst surface active site density.

[0136] In summary, through the analysis of the embodiments and comparative examples, we can see the innovation and originality of the present invention in catalyst design and performance optimization, which provides new ideas and methods for research and application in the field of catalysis.

[0137] Test Example 2

[0138] The catalyst in Example 1 was measured at different n(H 2 S) / n(SO 2 ), pressure and temperature on the sulfur recovery rate. The results are shown in Table 2-4.

[0139] Table 2n(H 2 S) / n(SO 2 ) on sulfur recovery rate

[0140] <![CDATA[n(H 2 S) / n(SO 2 )]]> Sulfur recovery rate YS (%) 1.7 97.4 1.8 97.5 1.9 98.2 2.0 98.5 2.1 98.0

[0141] Table 3 Effect of pressure on sulfur recovery rate YS (%)

[0142] Pressure(KPa) Sulfur recovery rate YS (%) 10 98.2 20 98.1 40 95.4 60 92.7 80 88.6 100 83.4

[0143] Table 4 Effect of temperature on sulfur recovery rate YS (%)

[0144] Temperature(℃) Sulfur recovery rate YS (%) 150 98.5 180 98.4 210 98.2 240 98.0 270 97.7 310 97.5

[0145] Optimize the adsorbent-catalyst and adsorbent sulfur recovery process, reduce side reactions and tail gas composition tests. In order to obtain the highest sulfur recovery rate, n(H 2 S) / n(SO 2 ) is basically maintained at a stoichiometric ratio of 2, and the exhaust SO 2 Very small; ensures both COS and CS 2 hydrolysis, therefore, the reactor needs to be maintained at a relatively high temperature, and the catalytic conversion reaction temperature is generally controlled at 150°C-310°C. Optimization of adsorption process conditions. This experiment selected 13X with an intermediate particle size of 0.5-0.3mm as the molecular sieve adsorption experimental conditions. As the bed height increased, the space velocity ratio increased, and the penetration time and saturation time increased significantly. When the bed height was 4cm, the penetration time reached 196min, and the penetration sulfur capacity was 45.3mg / g. The desulfurization performance of Zn-Fe / 13X adsorbent at three different temperatures of 20°C, 40°C and 80°C was different. As the temperature increased, the desulfurization performance of the molecular sieve gradually decreased, the penetration time was shortened, and H 2 The S gas stays on the adsorbent for a shorter time, and the adsorbent is quickly saturated after penetration. In order to obtain the highest sulfur recovery rate, the n(H 2 S) / n(SO 2 ) is around 2. Higher H 2 S concentration is beneficial to increase H 2 The sulfur recovery reaction tends to be carried out at low atmospheric pressure. The higher the pressure, the worse the effect. The temperature of the catalytic reactor has a significant effect on the total sulfur recovery rate. When the reactor temperature is reduced from 310℃ to 150℃, 3% H 2 The total sulfur recovery rate of acid gas increases with the S concentration.

[0146] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims

1. A bifunctional catalyst, characterized in that: The catalyst comprises: a carrier and a metal active component loaded on the carrier, wherein the carrier is a modified 13X molecular sieve, and the metal active component is Fe2O3 and ZnO; wherein, based on the total weight of the catalyst, the content of Fe2O3 is 4-5wt%, the content of ZnO is 2-2.5wt%, and the specific surface active site density of the catalyst is 1000-1500 / m 2 .

2. The catalyst according to claim 1, characterized in that The silicon-aluminum ratio of the modified 13X molecular sieve is 2-5:1; Preferably, the average particle size of the catalyst is 0.3-0.5 mm; Preferably, the specific surface area of ​​the catalyst is 300-500m 2 / g; Preferably, the pore volume of the catalyst is 0.3-0.5 cm 3 / g.

3. The catalyst according to claim 1 or 2, characterized in that The pH value of the surface acidity and alkalinity of the modified 13X molecular sieve is 8-9.

5.

4. A method for preparing a bifunctional catalyst, characterized in that: include: (1) exchanging the 13X molecular sieve with an alkaline solution, and obtaining a modified 13X molecular sieve after ultrasonication and drying; (2) The modified 13X molecular sieve is mixed with a solution containing zinc salt and iron salt, dried, and calcined to prepare the bifunctional catalyst.

5. The preparation method according to claim 4, characterized in that: The modified 13X molecular sieve has a silicon-aluminum ratio of 2-5:1, an average particle size of 0.3-0.5 mm, and a specific surface area of ​​300-500 m 2 / g, pore volume is 0.3-0.5cm 3 / g.

6. The preparation method according to claim 4 or 5, characterized in that: The alkaline solution is selected from one or more of NaOH solution, KOH solution, and NH4OH; Preferably, the zinc salt is selected from one or more of zinc nitrate, zinc sulfate and zinc chloride; Preferably, the iron salt is selected from one or more of ferric nitrate, ferric sulfate and ferric chloride.

7. The preparation method according to any one of claims 4 to 6, characterized in that: In step (1), the ultrasonication time is 10-20 min, the drying temperature is 80-120° C., and the drying time is 2-4 h; Preferably, step (2) further comprises standing for 8-12 hours after the mixing; Preferably, in step (2), the drying temperature is 120-150° C., and the drying time is 3-6 hours; Preferably, in step (2), the calcination temperature is 300-500° C., and the calcination time is 2-4 hours.

8. The preparation method according to any one of claims 4 to 7, characterized in that: Relative to 5-10 parts by weight of 13X molecular sieve and 10-20 mL of 25 wt% alkaline solution, the zinc salt and iron salt solution contains 0.5-1 parts by weight of zinc salt and 1-2 parts by weight of iron salt.

9. A bifunctional catalyst obtained by the preparation method according to any one of claims 4 to 8.

10. A method for adsorption catalysis of H2S, characterized in that: The method comprises: subjecting raw natural gas containing H2S to a desulfurization reaction in the presence of SO2 gas and a catalyst, wherein the catalyst is a bifunctional catalyst as claimed in any one of claims 1 to 3 and 9.

11. The method according to claim 10, characterized in that The desulfurization reaction temperature is 150-250℃, and the desulfurization reaction pressure is 0.5-5MPa; Preferably, the amount of SO2 gas introduced satisfies a molar ratio of H2S to SO2 of 1-3, preferably 2; Preferably, the airspeed is 200-500h -1 The volume fraction of H2S in the raw natural gas is 1.6-2%.

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