A nickel alloy, a 3D printing preparation method thereof, a skeleton-type nickel alloy catalyst and applications thereof

Abstract

This application relates to the technical field of catalysts, and specifically discloses a nickel alloy, a 3D printing preparation method thereof, a skeletal nickel alloy catalyst, and applications. The nickel alloy disclosed in this application includes the following elements in parts by weight: 449-78 parts of Ni, 12-23 parts of Al, 0-33 parts of X; the X is one or more of Co, Cr, and Mo; the weight ratio of the Ni element to the Al element is (2.5-4.5):1. This application also discloses a 3D printing preparation method of the above nickel alloy, a skeletal nickel alloy catalyst prepared using the nickel alloy, and applications. Using the nickel alloy disclosed in this application, a skeletal nickel alloy catalyst with a high specific surface area, high catalytic activity, and excellent mechanical properties can be obtained.

Description

Technical Field

[0001] This application relates to the technical field of catalysts, and particularly relates to a nickel alloy, a 3D printing preparation method thereof, a skeletal nickel alloy catalyst and applications thereof. Background Art

[0002] Environmental problems are one of the main challenges faced by humanity currently, and the use of clean energy has received extensive attention from society. Among them, synthetic natural gas, as a clean energy source, has attracted people's attention. Using synthetic natural gas can effectively reduce carbon emissions, thereby reducing environmental pollution. At the same time, synthetic natural gas produced from coal through coal gasification and methanation can make more rational use of coal resources, thereby meeting the market demand for natural gas in coal-rich countries.

[0003] In the research process of synthetic natural gas produced from coal, the synthesis of CO hydrogenation to methane is a very important type of reaction. In this type of reaction, industrial production usually requires the use of a catalyst for catalytic reaction; the skeletal nickel alloy catalyst developed by M. Raney has the advantages of low cost, simple preparation method, and good catalytic effect, and has extensive applications in the preparation method of synthetic natural gas.

[0004] As a fixed-bed reactor catalyst, the preparation methods of the skeletal nickel alloy catalyst mainly include co-precipitation, sol-gel, microemulsion, plasma and other methods. Among them, the mechanical properties of the catalysts prepared by the co-precipitation method, sol-gel method, and microemulsion method are poor, and they are extremely prone to vibration damage, abrasion, pollution, etc. when the carrier gas flow rate fluctuates. In severe cases, the pipeline will be blocked; while the plasma preparation method has a high cost and is not suitable for industrial production. Summary of the Invention

[0005] In order to solve the above problems, this application provides a nickel alloy, a 3D printing preparation method thereof, a skeletal nickel alloy catalyst and applications thereof.

[0006] In a first aspect, this application provides a nickel alloy, the nickel alloy is NiAlX, and includes the following elements in each weight part: 49 - 78 parts of Ni, 12 - 23 parts of Al, 0 - 33 parts of X; the X is one or more of Co, Cr, Mo;

[0007] The weight ratio of the Ni element to the Al element is (2.5 - 4.5):1.

[0008] The nickel alloy provided by the present application using the above-mentioned elemental composition by weight can be used as a precursor of a skeletal nickel alloy catalyst to obtain a catalyst with a relatively high specific surface area, high catalytic activity, and excellent mechanical properties; the nickel alloy can also use simple substances or alloys with Co, Cr, and Mo as the main elements as additives; due to the special arrangement of the outermost electrons of the above-mentioned additives, the relevant properties of the skeletal nickel alloy catalyst can be effectively improved, such as product selectivity, hydrogen adsorption, or inhibition of carbon deposition formation.

[0009] Preferably, the weight ratio of the Ni element to the Al element is (2.5 - 3.5):1.

[0010] Preferably, the nickel alloy includes the following elements in parts by weight: 49 - 57 parts of Ni, 12 - 20 parts of Al, and 28 - 33 parts of X.

[0011] Preferably, in the nickel alloy: X is CoCrMo, and the weight ratio of each element in CoCrMo is: Co:Cr:Mo = (54 - 67):(21 - 26):(5 - 8).

[0012] Through experimental analysis, it can be known that the present application selects the above CoCrMo as an additive and controls the elemental composition in CoCrMo, which can significantly improve the catalytic activity and mechanical properties of the skeletal nickel catalyst.

[0013] In the second aspect, the present application provides a 3D printing preparation method for the above nickel alloy, including the following steps:

[0014] Feed the powder raw materials of each element simultaneously at a powder feeding speed of 2 - 4 r / min to obtain a premix;

[0015] Use the LENS technology to perform 3D printing and forming on the premix; the process parameters of the LENS technology are: laser power 200 - 300 W, scanning speed 40 - 60 cm / min, layer thickness 10 - 30 μm, oxygen content < 20 ppm, and filling spacing 60 - 90 μm.

[0016] The laser engineered net shaping technology (LENS) adopted by the present application has the advantages of high forming efficiency and good cooling effect; at the same time, LENS can transport raw material powders through multiple external powder feeders to prepare functional materials and gradient materials with different compositions. This method of adjusting the transport rate of different powder feeders can adjust the proportion of elemental powders during the printing process at any time, and thus quickly prepare a large number of new materials with different components, which plays an important role in the development of new materials. Therefore, the 3D printing method provided by the present application can prepare a nickel alloy with a designable composition, and further prepare a skeletal nickel catalyst with a designable composition.

[0017] Furthermore, the nickel alloy can form a stable alloy solid solution after being prepared by 3D printing. It can be stored in normal-temperature air, is convenient for transportation with low risk, can be stored for a long time and then activated for use, which can effectively reduce the transportation and use costs.

[0018] Both the shape and the scanning path of the nickel alloy prepared in this application can be designed. By adjusting parameters such as the scanning path and the filling rate, the macroscopic voids of the 3D printed formed sample can be adjusted to obtain a multi-porous formed sample; furthermore, the wettability of the NaOH solution on the formed sample can be effectively improved, the leaching time can be reduced, the production cost can be lowered, and at the same time, the specific surface area of the catalyst can be increased.

[0019] In a specific embodiment, the scanning path can be selected as: straight line, orthogonal, 45° cross, 60° cross and other multi-angle straight line crosses.

[0020] In a specific embodiment, the filling rate can be adjusted according to the needs of the bed layer design; the filling rate can be 10% - 100%.

[0021] In a specific embodiment, the filling rate can also be 10%, 30%, 60%, 80%, 100%.

[0022] In this application, by controlling the parameter of the filling rate during the 3D printing process, the performance of the nickel alloy and the skeletal nickel alloy catalyst can be regulated. Further, when the filling rate is selected in the range of 30 - 60%, the catalytic activity and mechanical properties of the catalyst can be improved simultaneously.

[0023] Preferably, the particle size of the powder raw materials of each element is 45 - 100 μm.

[0024] Preferably, the ratio of the powder feeding speed of the Ni powder to the Al powder is (2 - 3) : (2 - 4).

[0025] In a specific embodiment, the ratio of the powder feeding speed of the Ni powder to the Al powder can be 2 : 2, 2 : 3, 2 : 4, 3 : 2, 3 : 3, 3 : 4, 4 : 2, 4 : 3, 4 : 4.

[0026] Through experimental analysis, it can be known that by controlling the powder feeding ratio of the Ni powder to the Al powder within the above range in this application, a skeletal nickel catalyst with a high specific surface area can be obtained, and thus the activity of the catalyst can be effectively improved.

[0027] When X is used as an additive, the additive powder of X raw material can be pre-added to the main raw material or distributed by an additional powder feeder, with high operation freedom and can be freely selected. When the method of pre-adding the additive powder of X raw material to the main raw material is selected, the obtained powder cannot be stored for a long time. If the powder stands for too long, powder segregation with different densities will occur, affecting the uniformity, and the catalyst composition cannot be adjusted in real time, which will cause the problem of local overheating of the bed layer; however, this method can reduce the technical and equipment costs. When the method of using an additional powder feeder to distribute the additive powder of X raw material is selected, the catalyst performance can be regulated according to the design requirements of the bed layer.

[0028] Preferably, when X in the nickel alloy is CoCrMo, the weight ratio of each element in the X powder is: Co:Cr:Mo = (54 - 67):(21 - 26):(5 - 8).

[0029] Furthermore, the volume ratio of the X powder to the Al powder is (2 - 4):(6 - 8).

[0030] Through experimental analysis, it can be known that in this application, by selecting the above alloy powder as the additive powder and controlling the volume ratio of the additive powder to the Al powder, the mechanical properties of the skeletal nickel catalyst can be significantly improved, and at the same time, the activity of the catalyst can be effectively enhanced.

[0031] In a third aspect, this application provides a skeletal nickel alloy catalyst, which is prepared by using the above nickel alloy.

[0032] Preferably, the specific surface area of the skeletal nickel alloy catalyst is 2 - 42 m 2 / g.

[0033] In a fourth aspect, this application provides a preparation method of the above skeletal nickel alloy catalyst, which is characterized in that the nickel alloy sample is immersed in a NaOH solution with a concentration of 4 - 6 mol / L to obtain the finished product;

[0034] The conditions of the immersion treatment are: immersion temperature 20 - 80 °C, immersion time 2 - 18 h.

[0035] In this application, by adjusting the powder feeding speeds of Ni powder and Al powder, the content ratio of Ni element and Al element in the nickel alloy is further controlled, and the LENS technology is used to select appropriate process parameters for 3D printing forming. Then, after immersion treatment with NaOH solution, soluble elements such as Al and Si can be removed to obtain a porous skeletal nickel catalyst with a high specific surface area and high mechanical properties.

[0036] Furthermore, after the nickel alloy is immersed in the NaOH solution, elements Al and Si react with NaOH and dissolve in the solution. The catalyst exhibits different specific surface areas after leaching. As the specific surface area increases, the active sites of the catalyst also increase, and the catalyst exhibits different catalytic performances.

[0037] Furthermore, the skeletal nickel alloy catalyst is mainly composed of Ni-Al solid solution materials. After being immersed in the NaOH solution after 3D printing and forming, the material can maintain a complete main structure. The alloy catalyst can directly replace the traditional carrier and has good mechanical properties; there are no problems of surface layer shedding and coating wear in the reactor.

[0038] Preferably, the conditions for the immersion treatment are: immersion temperature 40 - 60 °C, immersion time 6 - 18 h.

[0039] In a specific embodiment, the immersion temperature can be 20 °C, 40 °C, 60 °C, 80 °C.

[0040] In some specific embodiments, the immersion time can be 2 h, 6 h, 12 h, 18 h.

[0041] Through experimental analysis, it can be seen that as the immersion temperature and time increase, the surface of the catalyst material is further corroded, showing more obvious pores, and the specific surface area increases accordingly; however, too many pores will reduce the mechanical properties of the catalyst material. In order to enable the catalyst material to obtain good specific surface area and mechanical properties at the same time, the temperature and time of the NaOH solution immersion treatment in this application are controlled within the above ranges.

[0042] In a specific embodiment, the skeletal nickel alloy catalyst needs to be reduced by hydrogen to activate the catalyst. Fifthly, this application provides a composite structure reactor, including the nickel alloy and stainless steel, and the nickel alloy and the stainless steel are integrally formed.

[0043] Using the preparation method provided by this application, the 3D printed and formed nickel alloy and stainless steel are integrally formed, and the obtained composite structure reactor has a compressive strength of 850 - 1000 MPa under 10% strain.

[0044] Sixthly, this application provides a preparation method for the above composite structure reactor, which specifically includes the following steps:

[0045] Adopt a forming process from the inside out, and use the LENS technology to deposit stainless steel layer by layer on the outer protective part of the nickel alloy;

[0046] The LENS technical process parameters in the preparation method of the stainless steel are as follows: the raw material composition is 316L stainless steel powder, the powder feeding speed is 3 - 6 r / min, the laser power is 320 - 380 W, the scanning speed is 15 - 20 cm / min, the layer thickness is 10 - 30 μm, the oxygen content is < 60 ppm, and the filling spacing is 60 - 90 μm.

[0047] In a seventh aspect, the present application provides the use of the above-mentioned skeletal nickel alloy catalyst and the above-mentioned composite structure reactor in the preparation of synthetic natural gas from coal.

[0048] The preparation of synthetic natural gas is an exothermic reaction. In a fixed-bed reactor, local overheating problems are extremely likely to occur, affecting the chemical reaction process.

[0049] The present application can analyze and design the synthesis process of the reactor, and use different active catalysts at different positions in the reactor. The catalysts with different activities can be added at different positions in the reactor to improve problems such as too high activity of some catalysts and local overheating caused by violent reactions in some parts; make the temperature distribution in the reactor uniform, make the reaction more smooth, and prevent the inactivation of some catalysts.

[0050] In summary, the technical solution of the present application has the following effects:

[0051] 1. The nickel alloy provided by the present application can be used as a precursor of the skeletal nickel alloy catalyst to obtain a catalyst with a relatively high specific surface area, high catalytic activity, and excellent mechanical properties; the nickel alloy can also use simple substances or alloys with Co, Cr, and Mo as the main elements as additives; further improving the relevant properties of the catalyst.

[0052] 2. The present application uses a general atomized powder as a raw material in the preparation method of the nickel alloy, with low cost.

[0053] 3. In the LENS preparation method provided by the present application, the shape of the skeletal nickel alloy catalyst product can be designed, can be customized according to requirements, with high flexibility; the composition of the skeletal nickel alloy catalyst can be designed, and different active catalysts can be prepared at any time.

[0054] 4. The skeletal nickel alloy catalyst product obtained by 3D printing in the present application can be stored at room temperature, is convenient for transportation, and can reduce costs.

[0055] 5. The skeletal nickel alloy catalyst provided by the present application can be used as a main mechanical structure with certain mechanical properties, which can prevent the inactivation of some traditional catalysts.

[0056] 6. The skeletal nickel alloy catalyst provided by the present application can be added according to different reactor designs to improve the service life. Description of the Drawings

[0057] Figure 1 It is the morphology diagram of the skeletal nickel alloy catalyst in Example 5.

[0058] Figure 2 It is the morphology diagram of the skeletal nickel alloy catalyst in Example 3.

[0059] Figure 3 It is the morphology diagram of the skeletal nickel alloy catalyst in Example 23.

[0060] Figure 4 It is the catalytic activity of the skeletal nickel alloy catalysts in Example 3 and Example 10; among them, Figure 4 (a) is the conversion rate of CO, where Figure 4 (b) is the selectivity of CH4. Detailed implementation manners

[0061] The present application will be further described in detail below in combination with preparation examples, examples, comparative examples and performance detection tests. These examples should not be construed as limiting the scope claimed by the present application.

[0062] Preparation examples

[0063] Preparation Examples 1-5

[0064] Preparation Examples 1-5 respectively provide a nickel alloy.

[0065] The differences between the above preparation examples are: the powder feeding speeds of each raw material, as shown in Table 1 specifically.

[0066] The preparation method of the nickel alloy in the above preparation examples specifically includes the following steps: using Ni powder and Al powder with powder particle sizes of 45-100 μm as the main raw materials, and at the same time using CoCrMo alloy powder (the weight ratio of each element is: Co: Cr: Mo = 60: 24: 6) as the additive powder raw material; premixing the CoCrMo alloy powder and Al powder according to a volume ratio of 3: 7 to obtain Al-CoCrMo powder;

[0067] Using two external powder feeders, simultaneously conveying Ni powder and Al-CoCrMo powder according to the powder feeding speeds in Table 1 respectively to obtain a premixed material;

[0068] 3D printing: Using the LENS technology to perform 3D printing and forming on the premixed material to make a nickel alloy thin sheet with a size of 6 mm × 6 mm and a thickness of 1 mm. The process parameters of the LENS technology are: the scanning path is orthogonal, the laser power is 250 w, the scanning speed is 50 cm / min, the layer thickness is 25 μm, the oxygen content is 15 ppm, and the filling spacing is 75 μm.

[0069] Table 1 Powder feeding speeds of each raw material in Preparation Examples 1-5

[0070]

[0071] Preparation Examples 6 - 9

[0072] Preparation Examples 6 - 9 respectively provide a nickel alloy.

[0073] The differences between the above Preparation Examples and Preparation Example 3 are as follows: the process parameters of the LENS technology, as shown in Table 2 specifically; the raw materials used and other steps of the above Preparation Examples are the same as those of Preparation Example 3.

[0074] Table 2 Process Parameters of the LENS Technology in Preparation Examples 3, 6 - 9

[0075]

[0076] Preparation Example 10

[0077] This Preparation Example provides a nickel alloy.

[0078] The differences between this Preparation Example and Preparation Example 3 are as follows: the raw materials do not contain CoCrMo alloy powder as the additive powder; the remaining raw materials and process steps of this Preparation Example are the same as those of Preparation Example 3.

[0079] Preparation Example 11

[0080] This Preparation Example provides a nickel alloy.

[0081] The differences between this Preparation Example and Preparation Example 3 are as follows: using Mo elemental powder as the additive powder; pre - mixing the Mo elemental powder and Al powder in a volume ratio of 3:7 to obtain Al - Mo powder; the remaining raw materials, the powder feeding speed of the raw materials and the process steps of this Preparation Example are the same as those of Preparation Example 3.

[0082] Preparation Example 12

[0083] This Preparation Example provides a nickel alloy.

[0084] The differences between this Preparation Example and Preparation Example 3 are as follows: using Co elemental powder as the additive powder; pre - mixing the Co elemental powder and Al powder in a volume ratio of 3:7 to obtain Al - Co powder; the remaining raw materials, the powder feeding speed of the raw materials and the process steps of this Preparation Example are the same as those of Preparation Example 3.

[0085] Preparation Example 13

[0086] This Preparation Example provides a nickel alloy.

[0087] The difference between this Preparation Example and Preparation Example 3 is as follows: CoMo alloy powder (weight ratio of each element: Co:Mo = 60:6) is used as the additive powder; the CoMo alloy powder and Al powder are pre-mixed at a volume ratio of 3:7 to obtain Al-CoMo powder; the remaining raw materials, the powder feeding speed of the raw materials, and the process steps in this Preparation Example are the same as those in Preparation Example 3.

[0088] Preparation Example 14

[0089] This Preparation Example provides a nickel alloy.

[0090] The difference between this Preparation Example and Preparation Example 3 is as follows: CoCrMo alloy powder (weight ratio of each element: Co:Cr:Mo = 50:28:6) is used as the additive powder; the CoCrMo alloy powder and Al powder are pre-mixed at a volume ratio of 3:7; the remaining raw materials, the powder feeding speed of the raw materials, and the process steps in this Preparation Example are the same as those in Preparation Example 3.

[0091] Preparation Example 15

[0092] This Preparation Example provides a nickel alloy.

[0093] The difference between this Preparation Example and Preparation Example 3 is as follows: CoCrMo alloy powder (weight ratio of each element: Co:Cr:Mo = 60:24:6) is used as the additive powder; the CoCrMo alloy powder and Al powder are pre-mixed at a volume ratio of 2:9; the remaining raw materials, the powder feeding speed of the raw materials, and the process steps in this Preparation Example are the same as those in Preparation Example 3.

[0094] Preparation Example 16

[0095] This Preparation Example provides a nickel alloy.

[0096] The difference between this Preparation Example and Preparation Example 3 is as follows: CoCrMo alloy powder (weight ratio of each element: Co:Cr:Mo = 60:24:6) is used as the additive powder; the CoCrMo alloy powder and Al powder are pre-mixed at a volume ratio of 4:5; the remaining raw materials, the powder feeding speed of the raw materials, and the process steps in this Preparation Example are the same as those in Preparation Example 3.

[0097] Preparation Example 17

[0098] This Preparation Example provides a nickel alloy.

[0099] The difference between this Preparation Example and Preparation Example 3 is as follows: the powder feeding speed of Ni powder is 1.5 r / min, and the powder feeding speed of Al powder is 5 r / min; the remaining process steps in this Preparation Example are the same as those in Preparation Example 3.

[0100] Preparation Example 18

[0101] This preparation example provides a nickel alloy.

[0102] The difference between this preparation example and Preparation Example 3 is that the powder feeding rate of Ni powder is 5 r / min and the powder feeding rate of Al powder is 1.5 r / min; the remaining process steps of this preparation example are the same as those of Preparation Example 3.

[0103] Preparation Examples 19 - 22

[0104] Preparation Examples 19 - 22 respectively provide a skeletal nickel alloy catalyst.

[0105] The difference between Preparation Examples 19 - 22 and Preparation Example 3 is that the process parameters of the LENS technology are as shown in Table 3 specifically; the raw materials and other steps used in the above preparation examples are the same as those of Preparation Example 3.

[0106] Table 3 Process parameters of the LENS technology in Preparation Examples 19 - 22

[0107]

[0108] Performance detection test

[0109] An energy dispersive spectrometer (EDS) was used to calibrate the elemental composition of the nickel alloy samples prepared in Preparation Examples 1 - 22.

[0110] Detection result: The elemental composition of the nickel alloy samples is shown in Table 4.

[0111] Table 4 Detection results of the elemental composition of the nickel alloy samples in Preparation Examples 1 - 22

[0112]

[0113]

[0114] As can be seen from the table, in this application, by using the 3D printing preparation method, a nickel alloy NiAlX is obtained, which includes the following elements in parts by weight: 49 - 78 parts of Ni, 12 - 23 parts of Al, 0 - 33 parts of X; X is one or more of Co, Cr, Mo; and the weight ratio of Ni element to Al element is (2.5 - 4.5):1.

[0115] Examples 1 - 16

[0116] Examples 1 - 16 respectively provide a skeletal nickel alloy catalyst.

[0117] The difference in the above examples is that the sources of the nickel alloy are different, as shown in Table 5 specifically.

[0118] The nickel alloy samples prepared in the preparation examples were put into a 5 mol / L NaOH solution, soaked at 40 °C for 2 h, and dried at room temperature to obtain the finished products.

[0119] Catalyst activation: When using the skeletal nickel alloy catalyst, it needs to be reduced by hydrogen to activate the catalyst.

[0120] Table 5 Sources of nickel alloys in Examples 1-16

[0121] Example Source of nickel alloy Example Source of nickel alloy 1 Preparation Example 1 9 Preparation Example 9 2 Preparation Example 2 10 Preparation Example 10 3 Preparation Example 3 11 Preparation Example 11 4 Preparation Example 4 12 Preparation Example 12 5 Preparation Example 5 13 Preparation Example 13 6 Preparation Example 6 14 Preparation Example 14 7 Preparation Example 7 15 Preparation Example 15 8 Preparation Example 8 16 Preparation Example 16

[0122] Examples 17-24

[0123] Examples 17-24 respectively provide a skeletal nickel alloy catalyst.

[0124] The differences between the above examples and Example 3 are as follows: The temperature and time conditions of the soaking treatment with 5 mol / L NaOH solution are different, as shown in Table 6 specifically; the raw materials and other process steps of the above examples are the same as those of Example 3.

[0125] Table 6 Conditions of the soaking treatment with NaOH solution in Examples 3, 17-24

[0126] Example Immersion temperature (°C) Immersion time (h) 3 40 2 17 40 6 18 40 12 19 40 18 20 20 2 21 60 2 22 80 2 23 80 12 24 80 18

[0127] Comparative examples

[0128] Comparative examples 1-6

[0129] Comparative examples 1-6 respectively provide a skeletal nickel alloy catalyst.

[0130] The differences between the above comparative examples and Example 3 are as follows: The sources of the nickel alloys are different; the nickel alloys in Comparative examples 1-6 are respectively from Preparation examples 17-22; the remaining steps of the above comparative examples are the same as those of Example 3.

[0131] Performance detection test

[0132] (1) Morphology observation of the skeletal nickel alloy catalyst

[0133] The surface morphology of the sample was observed by scanning electron microscopy (SEM, JEB6510, JEOL, Japan).

[0134] The morphology of the skeletal nickel alloy catalyst in Example 5 is as Figure 1 shown, the morphology of the skeletal nickel alloy catalyst in Example 3 is as Figure 2 shown, the morphology of the skeletal nickel alloy catalyst in Example 23 is as Figure 3 shown,

[0135] From Figures 1 - 3From the morphology diagrams, it can be seen that in Example 5, the powder feeding rate of Ni powder is 4 r / min and the powder feeding rate of Al powder is 2 r / min. The prepared skeletal nickel alloy catalyst has a lower aluminum content, and the surface of the catalyst ( Figure 1 ) is relatively flat; while in Example 3, the powder feeding rate of Ni powder is 2 r / min and the powder feeding rate of Al powder is 4 r / min. The prepared skeletal nickel alloy catalyst has a higher aluminum content, and the surface of the catalyst ( Figure 2 ) is corroded to form a petal-like structure. Therefore, the catalyst with a rough petal-like structure in Example 3 can effectively increase the contact area with the reactants, thereby improving the catalytic ability of the catalyst; compared with the conditions of soaking in NaOH solution in Example 5, which are soaking temperature 40°C and soaking time 2 h, in Example 23, the soaking temperature is increased to 80°C and the soaking time is increased to 12 h. As the leaching temperature and time increase, the surface of the catalyst ( Figure 3 ) is further corroded, showing more obvious pores, resulting in an increase in the specific surface area of the catalyst and further improving the catalytic ability of the catalyst.

[0136] (2) Specific surface area of the skeletal nickel alloy catalyst

[0137] Detection method: Use a specific surface area analyzer (ASAP2460, Micromeritics, USA). Refer to the national standard GB / T24533-2009, and calculate the specific surface area of the sample based on N2 adsorption measurement and the BET method.

[0138] Detection results: As shown in Table 7.

[0139] (3) Catalytic activity of the skeletal nickel alloy catalyst

[0140] Detection method: Place the skeletal nickel alloy catalysts prepared in the examples and comparative examples on an adiabatic fixed-bed reactor to measure their activities. The specific steps are as follows: Load the skeletal nickel alloy catalyst into a stainless steel reaction tube, introduce pure hydrogen with a flow rate of 200 ml / min, 0.1 MPa, and a programmed heating rate of 1°C / min. Reduce the temperature at 400°C for 4 h under constant temperature; naturally cool down to 240°C, first slowly pressurize with nitrogen to 3 MPa, and then switch to H2:CO = 3:1 under the evaluation conditions, where the H2 flow rate is 300 ml / min, the CO flow rate is 100 ml / min, and the space velocity is 15000 h -1 , the reaction temperature is 260 - 280°C, and collect the activity data after the evaluation temperature is stable, and analyze the products using a gas chromatograph analyzer.

[0141] Figure 4 shows the catalytic activities of the skeletal nickel alloy catalysts in Example 3 and Example 10, where Figure 4 (a) is the conversion rate of CO, where Figure 4(b) is the selectivity of CH4.

[0142] The catalytic activities of the skeletal nickel alloy catalysts in Examples 1-24 and Comparative Examples 1-6 were evaluated by the average CO conversion rate and the average CH4 selectivity of the skeletal nickel alloy catalysts within the time period of 150-300 min. The test results are shown in Table 7.

[0143] (4) Mechanical properties

[0144] An inside-out forming process was adopted. First, nickel alloys were formed by using the 3D printing preparation methods in Examples 1-24 and Comparative Examples 1-6, and then stainless steel was deposited layer by layer on the outer protective part of the nickel alloy by using the LENS technology.

[0145] The process parameters of the LENS technology in the preparation method of stainless steel were as follows: the raw material composition was 316L stainless steel powder, the powder feeding speed was 4 r / min, the laser power was 350 W, the scanning speed was 18 cm / min, the layer thickness was 20 μm, the oxygen content was <60 ppm, and the filling spacing was 75 μm.

[0146] Then, the composite structure reactor formed by integrating nickel alloy and stainless steel was treated under the soaking treatment conditions of the NaOH solution in Examples 1-24 and Comparative Examples 1-6.

[0147] Detection method: The mechanical properties of the integrally formed composite structure reactor were tested. The surface was polished smooth and bright with sandpaper to eliminate the influence of stress concentration on the test. The reference standard was GB / T 228.1-2010. The compressive strength of the composite structure reactor was detected by using a universal mechanical testing machine with the sample at 10% strain to evaluate the mechanical properties of the skeletal nickel alloy catalyst. The test results are shown in Table 7.

[0148] Table 7 Performance test results of the skeletal nickel alloy catalysts in Examples 1-24 and Comparative Examples 1-6

[0149]

[0150]

[0151] Combined with the test results in Table 7, it can be seen that the specific surface area of the skeletal nickel alloy catalyst prepared by using the 3D printing preparation method provided by this application is 2-42 m 2 / g. In the catalytic activity test, the conversion rate of CO is 45.5 - 67.5%, and the selectivity of CH4 is 85.8 - 99.8%. Moreover, the composite structure reactor obtained by integrally forming the catalyst prepared in this application with stainless steel has a compressive strength of 850 - 1005 MPa under 10% strain. The above test results show that the skeletal nickel alloy catalyst prepared by using the technical solution provided in this application has a relatively high specific surface area, can effectively increase the contact area with the reactants, and thus improve the catalytic ability of the catalyst; and this catalyst has excellent mechanical properties.

[0152] Combining the test results in Table 4 and Table 7, by comparing the test results of Examples 1 - 5 and Comparative Examples 1 - 2, in Comparative Example 1, the powder feeding speed of Ni powder is less than 2 r / min, and the powder feeding speed of Al powder is greater than 4 r / min. Although the catalyst prepared has a relatively high specific surface area, its mechanical property is only 806 MPa; in Comparative Example 2, the powder feeding speed of Ni powder is greater than 4 r / min, and the powder feeding speed of Al powder is less than 2 r / min. Although the mechanical property of the catalyst prepared is relatively excellent, its specific surface area is only 0.2 m 2 / g, which reduces the catalytic activity of the catalyst. Therefore, in this application, by adjusting the powder feeding speeds of Ni powder and Al powder within the range of 2 - 4 r / min, the content ratio of Ni element and Al element in the catalyst is controlled, so that the prepared skeletal nickel alloy catalyst has a relatively high specific surface area, high catalytic activity, and relatively excellent mechanical properties.

[0153] Combining the test results in Table 4 and Table 7, by comparing the test results of Examples 3, 6 - 9 and Comparative Examples 3 - 6, when the power is 150 W, the molten pool depth is relatively shallow, the densities of Ni and Al elements in the molten pool are relatively low, and the content of Al in the nickel alloy is relatively high, which results in relatively poor mechanical properties of the catalyst; when the power reaches 350 W, the excessive energy density causes the low-melting-point Al to start volatilizing, reducing the content of Al in the nickel alloy, and thus reducing both the specific surface area and catalytic activity of the catalyst. In this application, appropriate process parameters are selected in the LENS technology to 3D print and form the catalyst, and the obtained skeletal nickel alloy catalyst has a relatively high specific surface area and high catalytic activity, and at the same time, the mechanical properties of the catalyst are relatively excellent.

[0154] Combining the test results in Table 4 and Table 7, by comparing the test results of Examples 3, 10 - 16, after adding the transition metal alloy containing Co, Cr, and Mo elements in this application, the conversion rate of CO and the selectivity of CH4 increase significantly, that is, the obtained skeletal nickel alloy catalyst has high catalytic activity.

[0155] By comparing the detection results of Examples 3 and 17-24, during the treatment process of soaking in NaOH solution, the present application controls the soaking temperature at 40-60 °C and the soaking time at 6-18 h, which improves the specific surface area of the catalyst and consequently enhances the catalytic activity of the skeletal nickel alloy catalyst.

[0156] Although the present invention has been described in detail with general descriptions and specific embodiments above, based on the present invention, some modifications or improvements can be made, which are obvious to those skilled in the art. Therefore, these modifications or improvements made without departing from the spirit of the present invention all fall within the scope of protection required by the present invention.

Claims

1. A nickel alloy, characterized in that, The nickel alloy is NiAlX, which is composed of the following elements in parts by weight: 49 - 78 parts of Ni, 12 - 23 parts of Al, and 0 - 33 parts of X; X is one or more of Co, Cr, and Mo; The weight ratio of the Ni element to the Al element is (2.5 - 4.5):1; The method for preparing the nickel alloy by 3D printing includes the following steps: Powder raw materials of each element are fed simultaneously at a powder feeding speed of 2 - 4 r / min to obtain a premix; The premix is 3D printed and formed by using the LENS technology; the process parameters of the LENS technology are: laser power 200 - 300 W, scanning speed 40 - 60 cm / min, layer thickness 10 - 30 μm, oxygen content < 20 ppm, and filling spacing 60 - 90 μm.

2. The nickel alloy according to claim 1, wherein In the nickel alloy: X is CoCrMo, and the weight ratio of each element in CoCrMo is: Co:Cr:Mo = (54 - 67):(21 - 26):(5 - 8).

3. The 3D printing preparation method of the nickel alloy according to any one of claims 1-2, characterized in that, It includes the following steps: Powder raw materials of each element are fed simultaneously at a powder feeding speed of 2 - 4 r / min to obtain a premix; The premix is 3D printed and formed by using the LENS technology; the process parameters of the LENS technology are: laser power 200 - 300 W, scanning speed 40 - 60 cm / min, layer thickness 10 - 30 μm, oxygen content < 20 ppm, and filling spacing 60 - 90 μm.

4. The 3D printing preparation method of the nickel alloy according to claim 3, characterized in that The particle size of the powder raw materials of each element is 45 - 100 μm.

5. The 3D printing preparation method of the nickel alloy according to claim 3, characterized in that, The powder raw materials of each element include Ni powder, Al powder, and X powder; when the X powder is used as an additive raw material, the volume ratio of the X powder to the Al powder is (2 - 4):(6 - 8).

6. A skeletal nickel alloy catalyst, characterized in that, The skeletal nickel alloy catalyst is prepared by using the nickel alloy according to any one of claims 1 - 2.

7. The preparation method of the skeletal nickel alloy catalyst according to claim 6, characterized in that, The nickel alloy is immersed in a NaOH solution with a concentration of 4 - 6 mol / L to obtain the finished product; The conditions for the immersion treatment are: immersion temperature 20 - 80 °C, immersion time 2 - 18 h.

8. A composite structure reactor, characterized in that, It includes the nickel alloy according to any one of claims 1 - 2 and stainless steel, and the nickel alloy and the stainless steel are integrally formed.

9. The preparation method of the composite structure reactor according to claim 8, characterized in that, Specifically, it includes the following steps: Adopting an in - out forming process, the stainless steel is deposited layer by layer on the outer protective part of the nickel alloy by using the LENS technology; The process parameters of the LENS technology in the preparation method of the stainless steel are: the raw material component is 316L stainless steel powder, the powder feeding speed is 3 - 6 r / min, the laser power is 320 - 380 W, the scanning speed is 15 - 20 cm / min, the layer thickness is 10 - 30 μm, the oxygen content < 60 ppm, and the filling spacing is 60 - 90 μm.

10. The application of the skeletal nickel alloy catalyst according to claim 6 or the composite structure reactor according to claim 8 in the coal - to - synthetic natural gas.

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