Hydrogenation / dechlorination conversion technology and preparation methods and applications of site-synergistic catalysts

Abstract

This invention provides a hydrogenation / dechlorination conversion technology and a method for preparing and applying a site-synergistic catalyst. The catalyst is designated as w-M1 / MoS2, and its structural characteristics are: the active component is stably and atomically dispersed on a MoS2 support with uniformly distributed pore size; metal atoms occupy edge S vacancies while also replacing Mo atoms in the basal region, forming a synergistically enhanced M1. δ+ -S / M1 0 -V s (0

Description

Technical Field

[0001] This invention belongs to the fields of petrochemicals, fine chemicals, and fluorochemicals, and specifically relates to hydrogenation / dechlorination conversion technology and the preparation method and application of site-synergistic catalysts. Background Technology

[0002] Supported metal catalysts are a large and important class of catalytic materials, playing a crucial role in petrochemicals, fine chemicals, coal chemicals, and environmental chemicals, particularly in selective hydrogenation and selective oxidation. Among these, site-isolated catalysts have attracted widespread attention due to their superior catalytic behavior, exhibiting the highest atom utilization, low coordination number, and strong interaction with the catalyst support. The traditional method for preparing supported metal catalysts is aqueous solution impregnation. However, due to the solvation effect of the impregnation solvent and the clustering effect of the active component, the active component is not easily highly dispersed. Furthermore, during subsequent reduction and heat treatment, the microcrystals of the active component tend to agglomerate and aggregate, ultimately leading to poor metal dispersion (especially at high loadings), which severely affects catalytic performance. Therefore, improving the degree and number of isolated active sites is crucial for enhancing catalyst performance, especially catalytic activity. To achieve this goal, researchers have proposed a new approach: reducing the size of active metal particles to the nanoscale or even atomic scale to maximize metal utilization efficiency. To improve catalytic performance, researchers have controlled the size and structure of the active component and selected suitable supports to enhance catalytic activity, selectivity, and stability.

[0003] For example, Orla M. Wilson et al., in their study "Effect of Pd Nanoparticle Size on the Catalytic Hydrogenation of Allyl Alcohol" (J. Am. Chem. Soc., 2006, 128, 4510-4511), investigated the effect of Pd size on catalytic activity using Pd as the active component. Their study found that smaller Pd particles were more beneficial for the catalytic hydrogenation of allyl alcohol compared to bulk catalysts, but their activity still needs further improvement. To address this issue, Academician Zhang Tao's research team, in their study "Single-Atom Catalysis of CO Oxidation Using Pt1 / FeO," explored the effect of Pd size on catalytic activity. x The concept of "single-atom catalysis" was proposed in Nat. Chem., 2011, 3, 634-640, and the single-atom catalyst Pt1 / FeO was successfully synthesized. xThe reaction rate in the CO oxidation reaction is twice that of ordinary Au / Fe2O3 catalysts. However, as the metal particle size decreases, the surface energy increases sharply, and metal atoms are prone to migration and aggregation during preparation and reaction, thus reducing catalyst stability. Feng et al., in "Enhancement of Metal Dispersion and Selective Acetylene Hydrogenation Catalytic Properties of A Supported Pd Catalyst, Ind. Eng. Chem. Res., 2011, 50, 1947-1954," prepared a highly dispersed Pd / MgO-Al2O3 catalyst using Al2O3 modified with layered MgAl-LDH as a support and applied it to the selective hydrogenation of alkynes. Compared with conventional Pd / Al2O3, the Pd / MgO-Al2O3 catalyst exhibits higher reactivity and longer-term stability. In their paper "Controlling Oxidation State of Pt Single-Atoms for Maximizing Catalytic Activity" (Angew. Chem. Int. Ed., 2020, 59, 20691-20696), Hyunjoo Lee et al. used defective CeO2-Al2O3 to anchor Pt single atoms and applied it to the oxidation reactions of CO, CH4, and NO. Their study found that, compared to conventional Pt / Al2O3, the defect-rich Pt1 / CeO2-Al2O3 catalyst facilitated the diffusion and adsorption of reactant molecules and the desorption of products, achieving a combined improvement in activity and selectivity. Therefore, selecting a suitable support is crucial for enhancing the activity, selectivity, and stability of catalysts.

[0004] MoS2 is a typical two-dimensional transition metal chalcogenide, with strong Mo-S covalent bonds within its layers and weaker van der Waals forces between them. Due to its tunable band structure and abundant edge defects, it can be widely used as a catalyst and support in heterogeneous catalytic reactions, providing a platform for the preparation of novel catalytic materials. Different defects, such as edge defects, sulfur / molybdenum vacancies, and dislocations, play important roles in altering the physicochemical properties of MoS2 and enhancing its reactivity. Zhang et al., in their paper "Defect-Rich MoS2 Ultrathin Nanosheets with Additional Active Edge Sites for Enhanced Electrocatalytic Hydrogen Evolution" (Adv. Mater., 2013, 25, 5807-5813), used MoS2 ultrathin nanosheets with edge defect sites as a catalyst and applied them to the electrocatalytic hydrogen evolution reaction. The study found that the catalytic activity of the defect-rich ultrathin nanosheets was 1.5 times higher than that of the defect-free ultrathin nanosheets, confirming that the construction of defects can improve catalytic activity. Meanwhile, the defect structure of MoS2 can also serve as a trapping center for active metals, further improving catalytic performance. For example, Chuan Xia et al., in their paper CN 115852418A, described a single-atom Pt catalyst supported on the edge sites of a monolayer MoS2 substrate, anchoring the active metal Pt at the edge sulfur vacancies of layered MoS2 to achieve atomic-level dispersion, thus obtaining a single-atom Pt / MoS2 catalyst. This catalyst was then used in the electrochemical reduction of oxygen to hydrogen peroxide, exhibiting a hydrogen peroxide selectivity as high as 45%. However, for most active metal loading methods, only the edge defects of MoS2 are utilized, leaving the large-area basal surface exhibiting reaction inertness and low support utilization. Therefore, it is urgent to develop new strategies that, while anchoring the active metal at the edge sites of the MoS2 support, also activate its inert basal surface sites, achieving efficient utilization of the support properties, which is crucial for improving catalytic performance.

[0005] Based on this, the present invention uses layered MoS2 with uniformly distributed pore size as a carrier, and employs a strong electrostatic adsorption-excess temperature-controlled impregnation strategy to load a hydrogenation-active transition metal M onto the surface of MoS2. Continuous heat treatment under inert and reducing atmospheres activates the edge and basal sites of MoS2, further inducing the active metal M to monodispersely occupy edge S vacancies while simultaneously replacing Mo atoms, thus constructing M1 with a strong synergistic effect. δ+ -S / M1 0 -V s The advantageous catalytic sites enable a combined improvement in the activity, selectivity, and stability of selective hydrogenation / dechlorination catalysts. Summary of the Invention

[0006] The purpose of this invention is to provide a hydrogenation / dechlorination conversion technology and a method for preparing and applying a site-synergistic catalyst.

[0007] The supported catalyst provided by this invention is denoted as w-M1 / MoS2, where M represents the active component, M1 represents an atomically dispersed active metal, and M is one of Ni, Pd, Pt, Co, Ru, Ga, Fe, and Cu, preferably Ni, Pd, or Fe, with MoS2 serving as the support; w represents the active metal M as a percentage of the catalyst mass, wherein w is 0.05–5.0 wt.%, preferably 0.5–3.5 wt.%; the structural feature of this catalyst is that the M1 active component is stably and atomically dispersed on a MoS2 support with uniformly distributed pore size. Through an inert-reducing atmosphere-programmed temperature-induction strategy, M1 is not only anchored by edge S defects but also successfully occupies basal Mo sites, exhibiting a geometrically discontinuous site state, forming M1 with adjacent S atoms and edge S vacancies. δ+ -S / M1 0 -V s Co-occurrence sites, 0 < δ < 2.

[0008] The specific steps of the above-mentioned hydrogenation / dechlorination conversion technology and site-synergistic catalyst preparation method provided by the present invention are as follows:

[0009] A. Dissolve the molybdenum source and sulfur source precursors in 30-80 mL of deionized water to obtain solution A and solution B. After stirring and dissolving at 20 °C, transfer solution A and solution B to a three-necked flask to obtain a mixed solution.

[0010] B. Slowly add 1-2 mol / L HCl solution dropwise to the mixed solution obtained in step A at a rate of 10 mL / min, stir at 20 °C for 2-6 h until a black precipitate appears in the solution, centrifuge and filter until the supernatant is neutral, and dry at 60-120 °C for 16-24 h to obtain MoS3. Place the prepared MoS3 in an atmosphere furnace and heat it to 500-700 °C at a rate of 2-10 °C / min for 1-3 h in a reducing atmosphere to obtain two-dimensional layered MoS2 with uniform pore size distribution between 19-30 nm.

[0011] C. The MoS2 with uniformly distributed pore size obtained in step B is uniformly dispersed in a soluble metal M salt solution, where the transition metal M is 0.05–5.0 wt.% of the support mass. A strong electrostatic adsorption-excess temperature-controlled impregnation strategy is employed, and the mixture is stirred at 200–500 rpm for 4–6 hours at 30–80°C until it reaches a viscous consistency. After drying in a constant-temperature drying oven at 50–120°C for 8–24 hours, wM is obtained. 2+ / MoS2 precursor;

[0012] D. The wM obtained in step C2+ The MoS2 precursor was placed in an atmosphere furnace and heated to 200–300 °C for 1–2 h in an inert atmosphere at a rate of 5–20 °C / min. It was then further treated at 250–350 °C for 2–3 h in a reducing atmosphere at a gas flow rate of 40–70 mL / min. After cooling to 20 °C, the w-M1 / MoS2 catalyst was obtained, possessing M1... 0 and M1 δ+ (0<δ<2) Active sites for synergistic effects.

[0013] The key features of this preparation method are: utilizing the abundant edge defects and tunable basal coordination structure of the layered MoS2 support, a strong electrostatic adsorption-excess temperature-controlled impregnation strategy is employed to coordinate and load the hydrogenation-active transition metal M. Through continuous driving in an inert-reducing atmosphere-programmed temperature rise, more MoS2 edge and basal sites are activated, causing the active metal M to occupy edge S vacancies while simultaneously replacing Mo atoms in the basal region, thereby constructing an M1 with synergistic enhancement. δ+ -S / M1 0 -V s Advantageous catalytic sites. This preparation method can precisely construct abundant vacancies in space, thereby achieving atomic-level dispersion of active metal species under high loading, solving the problem of agglomeration of small-sized active metal particles prepared by traditional methods. The preparation requires no surfactant and is simple in process. The prepared catalyst is mainly used in selective hydrogenation and dechlorination reactions in important fine chemical processes, exhibiting excellent activity, target product selectivity, and stability.

[0014] Figure 1 The X-ray diffraction (XRD) spectra of the 2.3% Ni1 / MoS2 catalyst and MoS2 prepared in Example 1 are shown in the figure. It can be seen from the figure that the catalyst before and after loading has similar crystal structure. No crystal structure of active metal Ni particles was observed, and it is preliminarily inferred that the metal is dispersed at the atomic level on the support.

[0015] Figure 2 The image shows a scanning transmission electron microscope (STEM) image of the 2.3% Ni1 / MoS2 catalyst prepared in Example 1. It can be seen from the image that no obvious particles were observed on the surface of the catalyst support, which further suggests that the active metal Ni is atomically dispersed.

[0016] Figure 3 The image shows the Ni 2p X-ray photoelectron spectroscopy (XPS) spectrum of the 2.3%-Ni1 / MoS2 catalyst prepared in Example 1. It can be seen from the figure that after continuous heat treatment in inert and reducing atmospheres, the Ni species exhibits valence states of δ+ and 0.

[0017] Figure 4The EPR spectrum of the 2.3% Ni1 / MoS2 catalyst prepared in Example 1 shows a sulfur vacancy characteristic peak at g = 2.003, indicating the presence of sulfur vacancies in the catalyst.

[0018] Figure 5 The X-ray photoelectron spectroscopy (XPS) spectra of Mo 3d and S2p of the MoS2 support and 2.3% Ni1 / MoS2 catalyst prepared in Example 1 are shown in the figure. The S2p of 2.3% Ni1 / MoS2 can be seen from the figure. 3 / 2 The spectrum shifts to lower energies (0.4 eV) compared to pure MoS2. This is because Ni atoms have a higher electronegativity than Mo atoms, resulting in a higher electron density for S atoms (bonded with Ni atoms). Furthermore, the content of high-valence Mo species increases significantly after Ni modification, indicating that the introduced Ni species replace Mo atoms in MoS2.

[0019] Figure 6 The experimental results for the selective hydrogenation of acetylene using the 2.3% Ni1 / MoS2 catalyst prepared in Example 1 are shown. a) is the curve of acetylene conversion versus reaction temperature, and b) is the curve of ethylene selectivity versus reaction temperature. When the reaction temperature is 200℃, the acetylene conversion is close to 100%, corresponding to an ethylene selectivity of 85%.

[0020] Figure 7 The figure shows the long-term stability test results of the 2.3%-Ni1 / MoS2 catalyst prepared in Example 1 in the selective hydrogenation reaction of acetylene. As can be seen from the figure, after 40 hours of continuous reaction, the catalyst performance did not change significantly, the conversion rate was still maintained at 60%, and the ethylene selectivity was still maintained at about 75±3%, indicating that the catalyst has good long-term recyclability.

[0021] The beneficial effects of this invention are:

[0022] This catalyst uses layered MoS2 with uniformly distributed pore size, prepared by acid solution-coprecipitation, as a support. A strong electrostatic adsorption-excess temperature-controlled impregnation strategy is employed to anchor active metal M single atoms based on MoS2's abundant edge vacancies and tunable basal plane structure. After continuous heat treatment in inert and reducing atmospheres, a catalyst with M1 is obtained. δ+ -S / M1 0 -V s A novel M1 / MoS2 catalyst with synergistic sites. The preparation conditions are mild, the process requires no surfactant, and the procedure is simple.

[0023] The prepared active metal components are atomically dispersed on the support surface, achieving effective isolation of continuous M sites. Furthermore, by effectively utilizing edge defects and basal sites, M1 is obtained with synergistic reinforcement from basal metal sites and edge S sites.δ+ -S / M1 0 -V s Advantageous Catalysis Center. This catalyst can be applied to C≡C selective hydrogenation and C-Cl bond hydrogenation and dechlorination reactions. It exhibits excellent hydrogenation activity and selectivity while achieving reduction and effective substitution of precious metals. It has outstanding catalytic performance, is easy to recover and reuse, and has good stability. Attached Figure Description

[0024] Figure 1 X-ray diffraction (XRD) spectra of the 2.3% Ni1 / MoS2 catalyst and MoS2 prepared in Example 1.

[0025] Figure 2 Scanning transmission electron microscopy (STEM) images and mapping images of the 2.3% Ni1 / MoS2 catalyst prepared for Example 1.

[0026] Figure 3 The Ni 2p X-ray photoelectron spectroscopy (XPS) spectrum of the 2.3% Ni1 / MoS2 catalyst prepared in Example 1.

[0027] Figure 4 The EPR spectrum of the 2.3% Ni1 / MoS2 catalyst prepared in Example 1 is shown.

[0028] Figure 5 The X-ray photoelectron spectroscopy (XPS) spectra of the MoS2 support and the 2.3% Ni1 / MoS2 catalyst Mo 3d and S2p prepared in Example 1 are shown.

[0029] Figure 6 The experimental results of the 2.3%-Ni1 / MoS2 catalyst prepared in Example 1 in the selective hydrogenation reaction of acetylene are shown in Figure a. The curve of acetylene conversion versus reaction temperature is shown in Figure b. The curve of ethylene selectivity versus acetylene conversion is shown in Figure b.

[0030] Figure 7 Stability curves of the 2.3% Ni1 / MoS2 catalyst prepared in Example 1 in the selective hydrogenation reaction of acetylene. Detailed Implementation

[0031] Example 1

[0032] A. Take 4.0g of (NH4)6Mo7O 24 ·4H2O and 17.5075gNa2S·9H2O were dissolved in 50mL of deionized water to obtain solution A and solution B, respectively. After stirring and dissolving at 20℃, solution A and solution B were simultaneously transferred to a three-necked flask to obtain a mixed solution.

[0033] B. 1.5 mol / L HCl solution was slowly added dropwise to the mixed solution obtained in step A at a rate of 10 mL / min. The mixture was stirred at 20 °C for 4 h until a black precipitate appeared in the solution. The mixture was centrifuged and filtered until the supernatant was neutral. The supernatant was then dried at 60 °C for 24 h to obtain MoS3. The prepared MoS3 was placed in an atmosphere furnace and heated to 600 °C at a rate of 10 °C / min for 2 h in a 10 vol.% H2 / N2 mixed gas to obtain two-dimensional layered MoS2 with uniform pore size distribution between 19 and 30 nm.

[0034] C. The MoS2 with uniformly distributed pore size obtained in step B was uniformly dispersed in a soluble Ni salt Ni(NO3)2·6H2O solution, with the transition metal Ni being 2.3 wt.% of the support mass. A strong electrostatic adsorption-excess temperature-controlled impregnation strategy was employed, and the mixture was stirred at 300 rpm for 6 hours at 60°C until it reached a viscous state. After drying in a constant-temperature drying oven at 60°C for 24 hours, 2.3% Ni-N was obtained. 2+ / MoS2 precursor;

[0035] D. The 2.3% Ni obtained in step C 2+ The MoS2 precursor was placed in an atmosphere furnace and heated to 300°C for 1 h in a N2 atmosphere at a rate of 10°C / min. It was then further treated at 300°C for 2 h by introducing a 10 vol.% H2 / N2 mixture at a gas flow rate of 50 mL / min. After cooling to 20°C, a 2.3% Ni1 / MoS2 catalyst was obtained, exhibiting Ni1... 0 and Ni1 δ+ (0<δ<2) Active sites for synergistic effects.

[0036] The catalyst prepared above was used in an experiment on the selective hydrogenation of acetylene:

[0037] 0.3g of catalyst was weighed and thoroughly mixed with 1.4g of quartz sand with a particle size of 40-70 mesh, and then loaded into a quartz reaction tube with a diameter of 7mm. The gas composition of the reaction feed gas was a balance gas of 0.33% acetylene / 1.99% hydrogen / 3.3% ethylene / nitrogen. The catalytic performance was tested at temperatures ranging from 25 to 250℃, with temperature intervals of 10℃, at atmospheric pressure, and with a space velocity of 9960 h⁻¹. -1 The composition and content of reactants and products were analyzed using gas chromatography, with sampling taken every 10 minutes. Results are shown below. Figure 6 and Figure 7 .

[0038] Depend on Figure 6 It is evident that the catalyst Ni1 / MoS2 with a loading of 2.3% achieved complete acetylene conversion at 200℃, with an ethylene selectivity of 85%. Figure 7It can be seen that after 40 hours of reaction, the acetylene conversion of the 2.3%-Ni1 / MoS2 catalyst still maintains a selectivity of about 75% at 60%, indicating that the catalyst has good long-term recyclability.

[0039] Example 2

[0040] A. Take 4.0g of (NH4)6Mo7O 24 ·4H2O and 17.5075gNa2S·9H2O were dissolved in 50mL of deionized water to obtain solution A and solution B, respectively. After stirring and dissolving at 20℃, solution A and solution B were simultaneously transferred to a three-necked flask to obtain a mixed solution.

[0041] B. 1.5 mol / L HCl solution was slowly added dropwise to the mixed solution obtained in step A at a rate of 10 mL / min. The mixture was stirred at 20 °C for 4 h until a black precipitate appeared in the solution. The mixture was centrifuged and filtered until the supernatant was neutral. The supernatant was then dried at 60 °C for 24 h to obtain MoS3. The prepared MoS3 was placed in an atmosphere furnace and heated to 600 °C at a rate of 10 °C / min for 2 h in a 10 vol.% H2 / N2 mixed gas to obtain two-dimensional layered MoS2 with uniform pore size distribution between 19 and 30 nm.

[0042] C. The MoS2 with uniformly distributed pore size obtained in step B was uniformly dispersed in a soluble Ni salt Ni(NO3)2·6H2O solution, with the transition metal Ni being 2.3 wt.% of the support mass. A strong electrostatic adsorption-excess temperature-controlled impregnation strategy was employed, and the mixture was stirred at 300 rpm for 6 hours at 60°C until it reached a viscous state. After drying in a constant-temperature drying oven at 60°C for 24 hours, 2.3% Ni-N was obtained. 2+ / MoS2 precursor;

[0043] D. The 2.3% Ni obtained in step C 2+ The MoS2 precursor was placed in an atmosphere furnace and heated to 300°C for 1 h in a N2 atmosphere at a rate of 10°C / min. It was then further treated at 300°C for 2 h by introducing a 10 vol.% H2 / N2 mixture at a gas flow rate of 50 mL / min. After cooling to 20°C, a 2.3% Ni1 / MoS2 catalyst was obtained, exhibiting Ni1... 0 and Ni1 δ+ (0<δ<2) Active sites for synergistic effects.

[0044] The catalyst prepared above was used in the selective hydrogenation reaction of 1,4-butynediol:

[0045] 0.3 g of catalyst and 1,4-butynediol working solution were weighed and placed into a reaction vessel. Hydrogen gas was introduced to the reaction pressure, and the temperature was heated to the reaction temperature before stirring was started. The catalytic performance was tested at 100℃, 450 rpm, with a 1,4-butynediol working solution concentration of 0.387 mol / L and a test pressure of 10 bar. The composition and content of the reactants and products were analyzed using gas chromatography, with sampling taken every 1 hour.

[0046] Table 1 Catalytic performance of 1,4-butynediol hydrogenation

[0047]

[0048] Example 3

[0049] A. Take 4.0g of (NH4)6Mo7O 24 ·4H2O and 17.5075gNa2S·9H2O were dissolved in 50mL of deionized water to obtain solution A and solution B, respectively. After stirring and dissolving at 20℃, solution A and solution B were simultaneously transferred to a three-necked flask to obtain a mixed solution.

[0050] B. 1.5 mol / L HCl solution was slowly added dropwise to the mixed solution obtained in step A at a rate of 10 mL / min. The mixture was stirred at 20 °C for 4 h until a black precipitate appeared in the solution. The mixture was centrifuged and filtered until the supernatant was neutral. The supernatant was then dried at 60 °C for 24 h to obtain MoS3. The prepared MoS3 was placed in an atmosphere furnace and heated to 600 °C at a rate of 10 °C / min for 2 h in a 10 vol.% H2 / N2 mixed gas to obtain two-dimensional layered MoS2 with uniform pore size distribution between 19 and 30 nm.

[0051] C. The MoS2 with uniformly distributed pore size obtained in step B was uniformly dispersed in a soluble Ni salt Ni(NO3)2·6H2O solution, with the transition metal Ni being 2.3 wt.% of the support mass. A strong electrostatic adsorption-excess temperature-controlled impregnation strategy was employed, and the mixture was stirred at 300 rpm for 6 hours at 60°C until it reached a viscous state. After drying in a constant-temperature drying oven at 60°C for 24 hours, 2.3% Ni-N was obtained. 2+ / MoS2 precursor;

[0052] D. The 2.3% Ni obtained in step C 2+ The MoS2 precursor was placed in an atmosphere furnace and heated to 300°C for 1 h in a N2 atmosphere at a rate of 10°C / min. It was then further treated at 300°C for 2 h by introducing a 10 vol.% H2 / N2 mixture at a gas flow rate of 50 mL / min. After cooling to 20°C, a 2.3% Ni1 / MoS2 catalyst was obtained, exhibiting Ni1... 0 and Ni1 δ+(0<δ<2) Active sites for synergistic effects.

[0053] The catalyst prepared above was used in the hydrogenation and dechlorination reaction of dichloroethane:

[0054] 0.3g of catalyst was weighed and thoroughly mixed with 1.4g of quartz sand with a particle size of 40-70 mesh, and then loaded into a quartz reaction tube with a diameter of 7mm. The gas composition of the reaction feed gas was a balance gas of 0.14% dichloroethane / 7% hydrogen / nitrogen. The catalytic performance was tested at temperatures ranging from 170 to 350℃, with temperature intervals of 10℃, at atmospheric pressure, and with a space velocity of 9900 h⁻¹. -1 Gas chromatography was used to analyze the composition and content of reactants and products, with sampling taken every 10 minutes.

[0055] Table 2 Catalytic performance of dichloroethane hydrodechlorination

[0056]

[0057] The 17Ni-PC@SBA-15 catalyst described in Chem. Commun. 2020, 56, 6985 exhibits a selectivity of 90% and a conversion rate of 65.5% in the hydrodechlorination of 1,2-dichloroethane at 300 °C. As shown in Table 1, compared to the 17Ni-PC@SBA-15 catalyst reported in the literature, the Ni1 / MoS2 catalyst prepared in this invention demonstrates higher activity and selectivity.

[0058] Example 4

[0059] A. Take 4.0g of (NH4)6Mo7O 24 ·4H2O and 17.5075gNa2S·9H2O were dissolved in 50mL of deionized water to obtain solution A and solution B, respectively. After stirring and dissolving at 20℃, solution A and solution B were simultaneously transferred to a three-necked flask to obtain a mixed solution.

[0060] B. 1.5 mol / L HCl solution was slowly added dropwise to the mixed solution obtained in step A at a rate of 10 mL / min. The mixture was stirred at 20 °C for 4 h until a black precipitate appeared in the solution. The mixture was centrifuged and filtered until the supernatant was neutral. The supernatant was then dried at 60 °C for 24 h to obtain MoS3. The prepared MoS3 was placed in an atmosphere furnace and heated to 600 °C at a rate of 10 °C / min for 2 h in a 10 vol.% H2 / N2 mixed gas to obtain two-dimensional layered MoS2 with uniform pore size distribution between 19 and 30 nm.

[0061] C. The MoS2 with uniformly distributed pore size obtained in step B was uniformly dispersed in a soluble Ni salt Ni(NO3)2·6H2O solution, with the transition metal Ni being 1.7 wt.% of the support mass. A strong electrostatic adsorption-excess temperature-controlled impregnation strategy was employed, and the mixture was stirred at 300 rpm for 6 hours at 60°C until it reached a viscous state. After drying in a constant-temperature drying oven at 60°C for 24 hours, 1.7% Ni-N was obtained. 2+ / MoS2 precursor;

[0062] D. Take the 1.7% Ni obtained in step C. 2+ The MoS2 precursor was placed in an atmosphere furnace and heated to 300°C for 1 h in a N2 atmosphere at a rate of 10°C / min. Then, a 10 vol.% H2 / N2 mixture was introduced and the mixture was treated at 300°C for 2 h at a gas flow rate of 50 mL / min. After cooling to 20°C, a 1.7% Ni1 / MoS2 catalyst was obtained.

[0063] The catalyst prepared above was used in an experiment on the selective hydrogenation of acetylene:

[0064] 0.3g of catalyst was weighed and thoroughly mixed with 1.4g of quartz sand with a particle size of 40-70 mesh, and then loaded into a quartz reaction tube with a diameter of 7mm. The gas composition of the reaction feed gas was a balance gas of 0.33% acetylene / 1.99% hydrogen / 3.3% ethylene / nitrogen. The catalytic performance was tested at temperatures ranging from 25 to 250℃, with temperature intervals of 10℃, at atmospheric pressure, and with a space velocity of 9960 h⁻¹. -1 Gas chromatography was used to analyze the composition and content of reactants and products, with sampling taken every 10 minutes.

[0065] Table 3 Catalytic performance of selective hydrogenation of acetylene

[0066]

[0067] Example 5

[0068] A. Take 4.0g of (NH4)6Mo7O 24 ·4H2O and 17.5075gNa2S·9H2O were dissolved in 50mL of deionized water to obtain solution A and solution B, respectively. After stirring and dissolving at 20℃, solution A and solution B were simultaneously transferred to a three-necked flask to obtain a mixed solution.

[0069] B. 1.5 mol / L HCl solution was slowly added dropwise to the mixed solution obtained in step A at a rate of 10 mL / min. The mixture was stirred at 20 °C for 4 h until a black precipitate appeared in the solution. The mixture was centrifuged and filtered until the supernatant was neutral. The supernatant was then dried at 60 °C for 24 h to obtain MoS3. The prepared MoS3 was placed in an atmosphere furnace and heated to 600 °C at a rate of 10 °C / min for 2 h in a 10 vol.% H2 / N2 mixed gas to obtain two-dimensional layered MoS2 with uniform pore size distribution between 19 and 30 nm.

[0070] C. The MoS2 with uniformly distributed pore size obtained in step B was uniformly dispersed in a soluble Ni salt Ni(NO3)2·6H2O solution, with the transition metal Ni being 3.5 wt.% of the support mass. A strong electrostatic adsorption-excess temperature-controlled impregnation strategy was employed, and the mixture was stirred at 300 rpm for 6 hours at 60°C until it reached a viscous state. After drying in a constant-temperature drying oven at 60°C for 24 hours, 3.5% Ni was obtained. 2+ / MoS2 precursor;

[0071] D. Take the 3.5% Ni obtained in step C. 2+ The MoS2 precursor was placed in an atmosphere furnace and heated to 300°C for 1 hour in a N2 atmosphere at a rate of 10°C / min. Then, a 10 vol.% H2 / N2 mixture was introduced and the mixture was treated at 300°C for 2 hours at a gas flow rate of 50 mL / min. After cooling to 20°C, a 3.5% Ni1 / MoS2 catalyst was obtained.

[0072] The catalyst prepared above was used in an experiment on the selective hydrogenation of acetylene:

[0073] 0.3g of catalyst was weighed and thoroughly mixed with 1.4g of quartz sand with a particle size of 40-70 mesh, and then loaded into a quartz reaction tube with a diameter of 7mm. The gas composition of the reaction feed gas was a balance gas of 0.33% acetylene / 1.99% hydrogen / 3.3% ethylene / nitrogen. The catalytic performance was tested at temperatures ranging from 25 to 250℃, with temperature intervals of 10℃, at atmospheric pressure, and with a space velocity of 9960 h⁻¹. -1 Gas chromatography was used to analyze the composition and content of reactants and products, with sampling taken every 10 minutes.

[0074] Table 4 Catalytic performance of selective hydrogenation of acetylene

[0075]

[0076] Example 6

[0077] A. Take 4.0g of (NH4)6Mo7O 24·4H2O and 17.5075gNa2S·9H2O were dissolved in 50mL of deionized water to obtain solution A and solution B, respectively. After stirring and dissolving at 20℃, solution A and solution B were simultaneously transferred to a three-necked flask to obtain a mixed solution.

[0078] B. 1.5 mol / L HCl solution was slowly added dropwise to the mixed solution obtained in step A at a rate of 10 mL / min. The mixture was stirred at 20 °C for 4 h until a black precipitate appeared in the solution. The mixture was centrifuged and filtered until the supernatant was neutral. The supernatant was then dried at 60 °C for 24 h to obtain MoS3. The prepared MoS3 was placed in an atmosphere furnace and heated to 600 °C at a rate of 10 °C / min for 2 h in a 10 vol.% H2 / N2 mixed gas to obtain two-dimensional layered MoS2 with uniform pore size distribution between 19 and 30 nm.

[0079] C. The MoS2 with uniform pore size distribution obtained in step B was uniformly dispersed in a soluble Pd salt Na2PdCl4 solution, where the transition metal Pd was 0.5 wt.% of the support mass. A strong electrostatic adsorption-excess temperature-controlled impregnation strategy was employed, and the mixture was stirred at 300 rpm for 6 hours at 60°C until it reached a viscous state. After drying in a 60°C constant-temperature drying oven for 24 hours, 0.5% Pd was obtained. 2+ / MoS2 precursor;

[0080] D. Take the 0.5% -Pd obtained in step C. 2+ The MoS2 precursor was placed in an atmosphere furnace and heated to 300°C for 1 h in a N2 atmosphere at a rate of 10°C / min. Then, a 10 vol.% H2 / N2 mixture was introduced and the mixture was treated at 300°C for 2 h at a gas flow rate of 50 mL / min. After cooling to 20°C, a 0.5% Pd1 / MoS2 catalyst was obtained.

[0081] The catalyst prepared above was used in an experiment on the selective hydrogenation of acetylene:

[0082] 0.3g of catalyst was weighed and thoroughly mixed with 1.4g of quartz sand with a particle size of 40-70 mesh, and then loaded into a quartz reaction tube with a diameter of 7mm. The gas composition of the reaction feed gas was a balance gas of 0.33% acetylene / 0.5% hydrogen / 3.3% ethylene / nitrogen. The catalytic performance was tested at temperatures ranging from 25 to 250℃, with temperature intervals of 10℃, at atmospheric pressure, and with a space velocity of 9960 h⁻¹. -1 Gas chromatography was used to analyze the composition and content of reactants and products, with sampling taken every 10 minutes.

[0083] Table 5 Catalytic performance of selective hydrogenation of acetylene

[0084]

[0085] Example 7

[0086] A. Take 4.0g of (NH4)6Mo7O 24 ·4H2O and 17.5075gNa2S·9H2O were dissolved in 50mL of deionized water to obtain solution A and solution B, respectively. After stirring and dissolving at 20℃, solution A and solution B were simultaneously transferred to a three-necked flask to obtain a mixed solution.

[0087] B. Add 1.5 mol / L HCl solution dropwise to the mixed solution obtained in step A at a rate of 10 mL / min, stir at 20 °C for 4 h until a black precipitate appears in the solution, centrifuge and filter until the supernatant is neutral, and dry at 60 °C for 24 h to obtain MoS3. Place the prepared MoS3 in an atmosphere furnace and heat it in CO at a rate of 10 °C / min to 550 °C for 2.5 h to obtain two-dimensional layered MoS2 with uniform pore size distribution between 19 and 30 nm.

[0088] C. The MoS2 with uniformly distributed pore size obtained in step B was uniformly dispersed in a soluble Ni salt Ni(NO3)2·6H2O solution, with the transition metal Ni being 2.3 wt.% of the support mass. A strong electrostatic adsorption-excess temperature-controlled impregnation strategy was employed, and the mixture was stirred at 300 rpm for 6 hours at 40°C until it reached a viscous state. After drying in a constant-temperature drying oven at 50°C for 24 hours, 2.3% Ni-N was obtained. 2+ / MoS2 precursor;

[0089] D. The 2.3% Ni obtained in step C 2+ The MoS2 precursor was placed in an atmosphere furnace and heated to 300°C for 2 hours in a N2 atmosphere at a rate of 5°C / min. Then, 10 vol.% H2 / N2 was introduced and the mixture was treated at 300°C for another 2 hours at a gas flow rate of 50 mL / min. After cooling to 20°C, a 2.3% Ni1 / MoS2 catalyst was obtained, exhibiting Ni1... 0 and Ni1 δ+ (0<δ<2) Active sites for synergistic effects.

[0090] The catalyst prepared above was used in an experiment on the selective hydrogenation of acetylene:

[0091] 0.3g of catalyst was weighed and thoroughly mixed with 1.4g of quartz sand with a particle size of 40-70 mesh, and then loaded into a quartz reaction tube with a diameter of 7mm. The gas composition of the reaction feed gas was a balance gas of 0.33% acetylene / 1.99% hydrogen / 3.3% ethylene / nitrogen. The catalytic performance was tested at temperatures ranging from 25 to 250℃, with temperature intervals of 10℃, at atmospheric pressure, and with a space velocity of 9960 h⁻¹. -1 Gas chromatography was used to analyze the composition and content of reactants and products, with sampling taken every 10 minutes.

[0092] Table 6 Catalytic performance of selective hydrogenation of acetylene

[0093]

Claims

1. A method for preparing a site-co-catalyst for hydrogenation or dechlorination conversion technologies, characterized in that... The specific steps are as follows: A. Dissolve the molybdenum source and sulfur source precursors in 30-80 mL of deionized water to obtain solution A and solution B. After stirring and dissolving at 20 °C, transfer solution A and solution B to a three-necked flask to obtain a mixed solution. B. Slowly add 1-2 mol / L HCl solution dropwise to the mixed solution obtained in step A at a rate of 10 mL / min, stir at 20℃ for 2-6 h until a black precipitate appears in the solution, centrifuge and filter until the supernatant is neutral, and dry at 60-120℃ for 16-24 h to obtain MoS3. Place the prepared MoS3 in an atmosphere furnace and heat it to 500-700℃ at a rate of 2-10℃ / min for 1-3 h in a reducing atmosphere to obtain two-dimensional layered MoS2 with uniform pore size distribution between 19-30 nm. C. The MoS2 with uniformly distributed pore size obtained in step B is uniformly dispersed in a soluble metal M salt solution, where the transition metal M is 0.05~2.3 wt.% of the support mass. A strong electrostatic adsorption-excess temperature-controlled impregnation strategy is employed, and the mixture is stirred at 200~500 rpm for 4~6 h at 30~80℃ until it reaches a viscous state. After drying in a constant temperature drying oven at 50~120℃ for 8~24 h, wM is obtained. 2+ / MoS2 precursor; D. The wM obtained in step C 2+ The / MoS2 precursor was placed in an atmosphere furnace and heated to 200-300 ºC for 1-2 h in an inert atmosphere at a rate of 5-20 ℃ / min. Then, a reducing atmosphere was introduced and the mixture was treated at 250-350 ℃ for 2-3 h at a gas flow rate of 40-70 mL / min. After cooling to 20 ℃, the w-M1 / MoS2 catalyst was obtained. The reducing atmosphere was a 10 vol.% H2 / N2 mixture. The catalyst is characterized by the stable and atomically dispersed M1 active component on a MoS2 support with uniformly distributed pore size. Through a continuous induction strategy involving an inert-reducing atmosphere and programmed temperature rise, M1 is not only anchored by edge S defects but also successfully occupies basal Mo sites, exhibiting a geometrically discontinuous site state. It forms M1 with adjacent S atoms and edge S vacancies. δ+ -S / M1 0 -V s Co-occurrence sites, 0 < δ < 2.

2. The preparation method according to claim 1, characterized in that: The molybdenum source is (NH4)6Mo7O 24 The molybdenum source is one of 4H2O, (NH4)2MoS4, or Na2MoO4, and the sulfur source is one of Na2S·9H2O, CH4N2S, C2H5NS, or KSCN. The molar ratio of the molybdenum source to the sulfur source is 1:5 to 1:

25.

3. The preparation method according to claim 1, characterized in that the concentration of the hydrochloric acid solution in step B is 1.5 mol / L, the reducing atmosphere is one of H2 or a 10 vol.% H2 / N2 mixture, and the treatment temperature is 550~650 ℃ for 1.5~2.5 h.

4. The preparation method according to claim 1, characterized in that the strong electrostatic adsorption-excess temperature-controlled impregnation strategy in step C, wherein the soluble metal M salt is one of Ni(NO3)2·6H2O, NiCl2·6H2O, Na2PdCl4, Pd(NO3)2, Pd(C5H7O2)2, H2PtCl6, CoCl2, RuCl3, Fe(NO3)3·9H2O, CuCl2·2H2O, and Cu(NO3)2.

5. The preparation method according to claim 1, characterized in that the inert treatment atmosphere in step D is one of N2, Ar and He.

6. A catalyst prepared by the method according to claim 1, characterized in that, The catalyst is denoted as w-M1 / MoS2, where M represents the active component, M1 represents an atomically dispersed active metal, and M is one of Ni, Pd, Pt, Co, Ru, Fe, and Cu; w represents the percentage of the active metal M by the mass of the support, and w is 0.05~2.3 wt.%.

7. The application of the catalyst as described in claim 6 in the selective hydrogenation of gas-phase acetylene to ethylene, characterized in that, The catalyst was weighed and thoroughly mixed with quartz sand with a particle size of 40-70 mesh, and then loaded into a quartz reaction tube with a diameter of 7 mm. A reaction gas was introduced, with a gas composition of 0.33%-0.6% acetylene / 0.6%-2.8% hydrogen / 3.3%-6% ethylene / nitrogen balance gas. The reaction was carried out at a temperature of 25-250 °C, a test pressure of 1-4 bar, and a space velocity of 6000-10000 h⁻¹. -1 Catalytic performance was tested under the specified conditions. The composition and content of reactants and products were analyzed by gas chromatography, with sampling taken every 10 minutes.

8. The application of the catalyst as described in claim 6 in the selective hydrogenation of alkynols to enols in the catalytic liquid phase, characterized in that, The catalyst and 1,4-butynediol working solution were weighed and placed into a reaction vessel, and hydrogen gas was introduced. The amount of catalyst was 0.20~0.50 g, the reaction temperature was 80~120 ℃, the rotation speed was 400~1000 rpm, the 1,4-butynediol working solution was 0.30~0.50 mol / L, and the test pressure was 8~12 bar. The composition and content of the reactants and products were analyzed by gas chromatography, and samples were taken every 1 hour.

9. The application of the catalyst as described in claim 6 in the selective hydrogenation and dechlorination of chlorinated organic compounds, characterized in that, The catalyst is weighed and thoroughly mixed with quartz sand with a particle size of 40-70 mesh, then loaded into a quartz reaction tube with a diameter of 7 mm. A reaction feed gas is introduced to carry out the catalytic reaction, wherein the gas composition is 0.14%-0.3% dichloroethane / 0.3%-7% hydrogen / nitrogen balance gas. The amount of catalyst used is 0.20-0.50 g, the reaction temperature is 170-350℃, and the space velocity is 2000-12000 h⁻¹. -1 Gas chromatography was used to analyze the composition and content of reactants and products, with sampling taken every 10 minutes.

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