WO2023024254A1 - 一种嵌入式耐水热NiSn-CS纳米催化剂及其制备方法和应用 - Google Patents

一种嵌入式耐水热NiSn-CS纳米催化剂及其制备方法和应用 Download PDF

Info

Publication number
WO2023024254A1
WO2023024254A1 PCT/CN2021/127576 CN2021127576W WO2023024254A1 WO 2023024254 A1 WO2023024254 A1 WO 2023024254A1 CN 2021127576 W CN2021127576 W CN 2021127576W WO 2023024254 A1 WO2023024254 A1 WO 2023024254A1
Authority
WO
WIPO (PCT)
Prior art keywords
nisn
hydrothermal
embedded
resistant
catalyst
Prior art date
Application number
PCT/CN2021/127576
Other languages
English (en)
French (fr)
Inventor
王铁军
陈铂
张浅
郑欣琪
仇松柏
Original Assignee
广东工业大学
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by 广东工业大学 filed Critical 广东工业大学
Publication of WO2023024254A1 publication Critical patent/WO2023024254A1/zh

Links

Images

Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J23/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
    • B01J23/70—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of the iron group metals or copper
    • B01J23/76—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of the iron group metals or copper combined with metals, oxides or hydroxides provided for in groups B01J23/02 - B01J23/36
    • B01J23/835—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of the iron group metals or copper combined with metals, oxides or hydroxides provided for in groups B01J23/02 - B01J23/36 with germanium, tin or lead
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J27/00—Catalysts comprising the elements or compounds of halogens, sulfur, selenium, tellurium, phosphorus or nitrogen; Catalysts comprising carbon compounds
    • B01J27/24—Nitrogen compounds
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J35/00—Catalysts, in general, characterised by their form or physical properties
    • B01J35/60—Catalysts, in general, characterised by their form or physical properties characterised by their surface properties or porosity
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
    • B01J37/02—Impregnation, coating or precipitation
    • B01J37/03—Precipitation; Co-precipitation
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
    • B01J37/08—Heat treatment
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C29/00—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom not belonging to a six-membered aromatic ring
    • C07C29/32—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom not belonging to a six-membered aromatic ring increasing the number of carbon atoms by reactions without formation of -OH groups
    • C07C29/34—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom not belonging to a six-membered aromatic ring increasing the number of carbon atoms by reactions without formation of -OH groups by condensation involving hydroxy groups or the mineral ester groups derived therefrom, e.g. Guerbet reaction
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C31/00—Saturated compounds having hydroxy or O-metal groups bound to acyclic carbon atoms
    • C07C31/02—Monohydroxylic acyclic alcohols
    • C07C31/12—Monohydroxylic acyclic alcohols containing four carbon atoms
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C31/00—Saturated compounds having hydroxy or O-metal groups bound to acyclic carbon atoms
    • C07C31/02—Monohydroxylic acyclic alcohols
    • C07C31/125—Monohydroxylic acyclic alcohols containing five to twenty-two carbon atoms
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P20/00—Technologies relating to chemical industry
    • Y02P20/50—Improvements relating to the production of bulk chemicals
    • Y02P20/52—Improvements relating to the production of bulk chemicals using catalysts, e.g. selective catalysts

Definitions

  • Chitosan (Chitosan, CS) is the product of deacetylation of chitin, is one of the most abundant natural biopolymers, and is also a rare natural alkaline polysaccharide, soluble in dilute acid solution. Chitosan has a wide range of applications in materials and other industries due to its non-toxic, odorless, and biodegradable properties. Chitosan mainly has two groups, amino group and hydroxyl group, which can coordinate with heavy metal ions to form stable chelate complexes. C4+ high-carbon alcohols are immiscible with water, non-corrosive, high energy density, and have an octane number close to that of gasoline, making them ideal advanced biofuels.
  • the Guerbet coupling reaction is an ideal choice for the synthesis of high-carbon alcohols from low-carbon alcohols. It is generally believed that the Guerbet coupling mechanism includes a multi-step reaction. First, the raw material alcohol is dehydrogenated to form an aldehyde, and then undergoes aldol condensation. The condensation product is dehydrated to form an alcohol. Saturated alkenals, and finally alkenals are hydrogenated to higher alcohols.
  • the homogeneous catalysts of iridium-based and ruthenium-based complexes have good catalytic performance, but there are disadvantages such as expensive iridium and ruthenium, difficult separation after reaction, and non-continuous operation.
  • Metal Ni as a non-precious metal element, is abundant in the earth's crust and is one of the best alternative materials for precious metals. The addition of metal Sn can change the electronic environment of metal Ni, and then regulate the metallicity of metal Ni, so that it can weaken the methanation during the dehydrogenation of small molecule alcohols, thus facilitating the formation of higher alcohols.
  • CN104289248A discloses a carbon nanotube composite material and its preparation method and application, which provides a composite material of a carbon layer coated carbon nanotube embedded with noble metal nanoparticles.
  • the carbon layer outside the carbon nanotubes is composed of noble metal nanoparticles embedded in the carbon layer, which effectively prevents the strong corrosion of the inner carbon nanotubes by high acidity and high voltage in the process of catalytic redox reaction, so that the catalyst maintains good electrical conductivity , improve the corrosion resistance stability and catalytic activity of the catalyst, but its cost is high, the preparation process is complicated, and the catalyst does not have good hydrothermal resistance.
  • the purpose of the present invention is to overcome the defects and deficiencies of poor particle dispersion and poor hydrothermal resistance of NiSn nano catalyst active components, and to provide a preparation method of embedded hydrothermal NiSn-CS nano catalyst, by combining Ni salt, Sn salt and shell The polysaccharides were mixed to form a sol solution, the solvent was removed to obtain a gel, and then carbonized to prepare an embedded hydrothermally resistant NiSn-CS nanocatalyst.
  • Another object of the present invention is to provide an embedded hydrothermal resistant NiSn-CS nano catalyst.
  • Another object of the present invention is the application of the embedded hydrothermal resistant NiSn-CS nano-catalyst in the synthesis of high-carbon alcohols from small molecule alcohols.
  • a kind of preparation method of embedded hydrothermal resistance NiSn-CS nanometer catalyst comprises the following steps:
  • Ni salt, Sn salt and chitosan are dissolved to form a sol solution
  • the carbonization temperature is 400-600° C.
  • the carbonization time is 1-4 hours.
  • the sol solution in step S1 can be prepared according to the following method: dissolve Ni salt, Sn salt and chitosan in 1-5wt% acetic acid aqueous solution, heat and stir at 60-90°C, and the stirring speed is 300-1000rpm, chitosan After the sugar is completely dissolved, a sol solution is formed.
  • the drying temperature of the sol solution in step S2 is 40-70°C, preferably 50°C; the carbonization temperature is preferably 500°C, if the carbonization temperature is too low, it will lead to insufficient carbonization of chitosan, incomplete exposure of metal active sites, and excessive carbonization temperature. It is easy to cause the agglomeration and growth of metal nanoparticles, thus affecting the catalytic activity of the catalyst.
  • the carbonization time is too short, the carbonization of chitosan will be insufficient, the metal ions cannot be completely reduced, and the metal active sites will be reduced; if the carbonization time is too long, the structure of the carbon layer will be destroyed, and the metal particles will agglomerate and grow, which will affect the catalyst. catalytic activity.
  • the Mw of the chitosan in step S1 is 700-250,000.
  • the Mw of the chitosan in step S1 is 100,000-150,000.
  • chitosan There are hydroxyl, amino, and carboxyl groups in chitosan, which can chelate with Ni ions and Sn ions, which is beneficial to the formation and dispersion of NiSn active sites in the catalyst, and at the same time, it is coated on the surface of NiSn nanoparticles to form a hydrothermally resistant catalyst structure.
  • the molar ratio of Ni salt and Sn salt in step S1 is 1:(0.03-0.24).
  • Ni salt to Sn salt is 1:0.06.
  • the molar ratio of the mixture of Ni salt and Sn salt to chitosan in step S1 is 1: (0.2-2).
  • the molar ratio of the mixture of Ni salt and Sn salt to chitosan in step S1 is 1: (1-1.5).
  • the molar ratio of the mixture of Ni salt and Sn salt to chitosan is too small, resulting in too few metal active sites of the catalyst, and the catalyst performance is poor; the molar ratio of the mixture of Ni salt and Sn salt to chitosan is too large, Chitosan cannot fully reduce metal ions, and NiSn nanoparticles cannot be fully embedded in the carbon layer, thereby reducing the activity of the catalyst.
  • NiSn-CS nano catalyst prepared by the above preparation method.
  • the embedded hydrothermal resistant NiSn-CS nano catalyst prepared by the invention can be applied to catalyze the synthesis of higher alcohols from small molecular alcohols.
  • the catalytic condition is that the mass ratio of NiSn-CS nano catalyst: inorganic base: small molecule alcohol: water is 1: (1 ⁇ 4): (10 ⁇ 43): (10 ⁇ 43), and the catalytic reaction temperature is 200 ⁇ 250°C, the pressure is 0.1-2Mpa, the more preferable catalytic conditions are NiSn-CS nano catalyst: inorganic base: small molecule alcohol: water mass ratio is 1:3:33:33, the catalytic reaction temperature is 230°C, the pressure is 0.1Mpa.
  • the invention provides an embedded hydrothermal resistant NiSn-CS nano-catalyst, the NiSn nano-particles in the catalyst are evenly distributed on the carbon layer, which significantly improves the dispersion of the NiSn catalytic active center and its structure and structure in the hydrothermal environment.
  • the stability of the activity when applied to the synthesis of high-carbon alcohols from small molecule alcohols, after 5 cycles of catalysis, its structure remains basically unchanged, and the conversion rate of ethanol is still as high as 65.7% (66.3% for the first time), and the selectivity of C4+ high-carbon alcohols Reaching 83.4%, showing excellent catalytic efficiency and hydrothermal resistance, easy to separate and recover, less pollution, and excellent recyclability.
  • the preparation method of the invention does not need complex pre-treatment, and the preparation process is simple.
  • Fig. 1 is the SEM figure of embedded hydrothermal resistance NiSn-CS nano-catalyst in the embodiment of the present invention 4;
  • Fig. 2 is the TEM figure under different magnifications of the embedded hydrothermal resistant NiSn-CS nanocatalyst in the embodiment 4 of the present invention
  • Fig. 3 is the TEM picture of the embedded hydrothermal resistant NiSn-CS nanocatalyst in Example 4 of the present invention after being catalyzed 5 times;
  • Fig. 4 is the TEM figure of embedded hydrothermal resistance NiSn-CS nano-catalyst in comparative example 3 of the present invention.
  • Fig. 5 is the TEM figure of embedded hydrothermal resistance NiSn-CS nano-catalyst in the embodiment of the present invention 6;
  • Fig. 6 is the TEM figure of embedded hydrothermal resistance NiSn-CS nano-catalyst in comparative example 2 of the present invention.
  • the raw material reagents used in the examples of the present invention are conventionally purchased raw material reagents.
  • step S2 Transfer the sol solution obtained in step S1 to a drying oven at 50°C for 48 hours to obtain a NiSn-CS nano-catalyst precursor, and then carbonize the catalyst precursor at 500°C for 2 hours in an N atmosphere to obtain an embedded hydrothermally resistant NiSn -CS nanocatalyst.
  • step S2 Transfer the sol solution obtained in step S1 to a drying oven at 50°C for 48 hours to obtain a NiSn-CS nano-catalyst precursor, and then carbonize the catalyst precursor at 500°C for 2 hours in an N atmosphere to obtain an embedded hydrothermally resistant NiSn -CS nanocatalyst.
  • a kind of preparation method of embedded hydrothermal resistance NiSn-CS nanometer catalyst comprises the steps:
  • Ni(NO 3 ) 2 ⁇ 6H 2 O, SnCl 4 ⁇ 5H 2 O and chitosan Mw: 100000
  • a certain amount of Ni(NO 3 ) 2 ⁇ 6H 2 O, SnCl 4 ⁇ 5H 2 O and chitosan Mw: 100000
  • Ni(NO 3 ) 2 6H 2 O: SnCl 4 5H 2 O: chitosan: acetic acid: water 1.84: 0.11: 1: 0.63: 50, that is, the metal precursor (Ni salt and Sn salt
  • the mol ratio of mixture) and chitosan monomer is 1:1;
  • the Mw of the chitosan in embodiment 4 step S1 is 150000, and other is the same as embodiment 3.
  • the Mw of the chitosan in step S1 of embodiment 5 is 250000, and other is the same as embodiment 3.
  • the carbonization treatment temperature in Step S2 of Embodiment 6 is 400° C., and the others are the same as Embodiment 4.
  • the carbonization treatment temperature in Step S2 of Example 7 is 600° C., and the others are the same as in Example 4.
  • the carbonization treatment time in Step S2 of Embodiment 9 is 4 hours, and the others are the same as Embodiment 4.
  • Step S1 of Example 10 The molar ratio of Ni salt, Sn salt mixture and chitosan in Step S1 of Example 10 is 1:1.5, and the others are the same as in Example 4.
  • Step S1 of Example 11 The molar ratio of Ni salt, Sn salt mixture and chitosan in Step S1 of Example 11 is 1:2, and the others are the same as in Example 4.
  • the carbonization treatment temperature in Step S2 of Comparative Example 1 is 300° C., and the others are the same as in Example 4.
  • the carbonization treatment temperature in Step S2 of Comparative Example 2 was 700° C., and the others were the same as in Example 4.
  • a kind of preparation method of NiSn nanometer catalyst comprises the steps:
  • Ni(NO 3 ) 2 ⁇ 6H 2 O and SnCl 4 ⁇ 5H 2 O into the aqueous acetic acid solution at the same time, and stir to form a uniform solution.
  • Fig. 1 and Fig. 2 are the SEM picture and the TEM picture of different magnifications of NiSn-CS nano-catalyst in embodiment 4 respectively, can find out from SEM picture that the catalyst that makes is mosaic structure, and carbon wraps NiSn nano particle to be embedded in carbon On the thin layer, the particle diameter is small and the dispersion is good.
  • Figure 3 is a TEM image of the product obtained in Example 4 after catalyzing 5 cycles, compared with the structure before the reaction ( Figure 2), it can be seen that the catalyst structure is stable.
  • Fig. 4 is a TEM image of the product prepared in Comparative Example 3, the NiSn nanoparticles are relatively large and the particles are seriously agglomerated.
  • FIG. 1 and Fig. 2 are the SEM picture and the TEM picture of different magnifications of NiSn-CS nano-catalyst in embodiment 4 respectively, can find out from SEM picture that the catalyst that makes is mosaic structure, and carbon wraps NiSn nano particle to be embedded
  • Example 5 is a TEM image of the product obtained in Example 6.
  • the NiSn nanoparticles in the catalyst are larger and the carbon layer is thicker.
  • 6 is a TEM image of the product obtained in Comparative Example 2.
  • the NiSn nanoparticles in the catalyst have a large particle size, are prone to aggregation, have poor dispersion, and have low reactivity.
  • the XRD of the products obtained in Examples 1 to 5 of the present invention is shown in Figure 7.
  • the molecular weight of chitosan increases, the characteristic diffraction peaks of metal Ni and NiSn-CS are gradually enhanced, and NiSn-CS plays a decisive role in the catalytic process. It shows that the carbon shell of chitosan as a carbon source is conducive to the stability of the metal center; but when the molecular weight of chitosan continues to increase, the crystal phase of metal Ni and NiSn-CS gradually weakens.
  • Example 4 Take the catalyst prepared in Example 4 above, and re-catalyze ethanol carbon-carbon coupling synthesis of higher fuel alcohol with homogeneous base (NaOH) in a magnetically stirred reactor.
  • the reaction conditions are the same as above, and the cycle is repeated 4 times.
  • the effect of the prepared catalyst on the catalytic synthesis of higher alcohols showed a trend of increasing first and then decreasing, which may be related to the effect of the catalyst wrapped on the surface of NiSn nanoparticles.
  • the thickness of the carbon shell is related to the thickness of the carbon shell. The appropriate thickness of the carbon shell is beneficial to protect the metal core of the catalyst and enhance its catalytic stability in the hydrothermal reaction environment, thereby improving the conversion rate of ethanol and the selectivity of liquid phase formation.
  • the thickness of the carbon shell continued to increase, which was not conducive to the material transfer between the aqueous phase and the active core of the catalyst metal during the reaction, and the conversion rate of ethanol declined.
  • Example 4 and Examples 6 to 7 and Comparative Examples 1 to 2 it can be known that the carbonization temperature is too low to cause insufficient carbonization of chitosan, and the metal active sites are not fully exposed; if the carbonization temperature is too high, it is easy to cause metal particles to agglomerate growth, thereby affecting the catalytic activity of the catalyst.
  • the embedded hydrothermal resistant NiSn-CS nanocatalyst prepared at the carbonization temperature of 500 °C has better catalytic activity.
  • Example 4 and Examples 8 to 9 too short a carbonization time will lead to insufficient carbonization of chitosan, metal ions cannot be completely reduced, and the metal active sites will be reduced; if the carbonization time is too long, the carbon layer will be destroyed. structure, and cause the metal particles to agglomerate and grow, thereby affecting the catalytic activity of the catalyst.
  • the embedded hydrothermal NiSn-CS nanocatalyst prepared when the carbonization time is 2h has better catalytic activity.
  • the mixture of Ni salt and Sn salt and the mol ratio of chitosan are too small, resulting in too few metal active sites of the catalyst and poor catalyst performance; Ni salt and Sn salt
  • the molar ratio of the mixture of Sn salt to chitosan was too large, chitosan could not sufficiently reduce metal ions, and NiSn nanoparticles could not be completely embedded in the carbon layer, thus reducing the activity of the catalyst.
  • the embedded hydrothermal resistant NiSn-CS nanocatalyst has better catalytic activity.
  • the catalyst prepared by the invention has excellent performance in the reaction of catalyzing the synthesis of C4+ higher carbon alcohols from ethanol, the highest ethanol conversion rate reaches 66.3%, and the selectivity of C4+ higher carbon alcohols reaches 85.1%.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Catalysts (AREA)

Abstract

本发明公开了一种嵌入式耐水热NiSn-CS纳米催化剂及其制备方法和应用。该方法包括以下步骤：先将Ni盐、Sn盐和壳聚糖溶解形成溶胶溶液，然后除去溶胶溶液中的溶剂得到凝胶，再将其碳化处理，获得嵌入式耐水热NiSn-CS纳米催化剂，其中，碳化温度为400～600℃，碳化时间为1～4h。本发明所制得的嵌入式耐水热NiSn-CS纳米催化剂显著提升了NiSn催化活性中心的分散性及其在水热环境下的结构和活性的稳定性，应用于小分子醇合成高碳醇时，表现出优异的催化效率和耐水热稳定性，且易于分离回收、污染小，具有优异的循环利用性。

Description

一种嵌入式耐水热NiSn-CS纳米催化剂及其制备方法和应用 技术领域
本发明涉及催化剂技术领域，更具体地，涉及一种嵌入式耐水热NiSn-CS纳米催化剂及其制备方法和应用。
背景技术
壳聚糖(Chitosan,CS)是甲壳素脱乙酰基的产物，是最丰富的天然生物高分子之一，也是少有的天然碱性多糖，可溶于稀酸溶液。壳聚糖由于其无毒、无味、可生物降解等特性在材料等行业具有广泛的应用。壳聚糖主要有氨基和羟基两种基团，可以与重金属离子配位形成稳定的螯合物。C4+高碳醇具有与水不混溶、无腐蚀性、能量密度高、接近汽油的辛烷值的特点，是理想的先进生物燃料。Guerbet偶联反应是实现低碳醇合成高碳醇的一种理想选择，通常认为Guerbet偶联机理包括多步反应，首先原料醇脱氢生成醛，然后进行醇醛缩合，缩合产物通过脱水生成不饱和的烯醛，最终烯醛通过加氢生成高碳醇。一般认为，醇脱氢和烯醛加氢是在金属催化剂的催化作用下进行的，羟醛缩合在酸或碱的作用下进行，因此低碳醇偶联制备高碳醇需要具有加氢-脱氢能力的金属催化剂和酸性或碱性催化剂。
目前，催化低碳醇偶联制备高碳醇的催化剂中，铱基和钌基络合物均相催化剂的催化性能良好，但是存在铱和钌价格昂贵、反应后难分离、不可连续操作等缺点。而金属Ni作为一种非贵金属元素，地壳中产量丰富，是最好的贵金属替代材料之一。金属Sn的加入可改变金属Ni的电子环境，进而调控金属Ni的金属性，使其在小分子醇脱氢过程中甲烷化减弱，从而利于高碳醇的生成。例如，CN104289248A中公开一种碳纳米管复合材料及其制备方法和应用，提供了一种嵌有贵金属纳米粒子的碳层包覆碳纳米管的复合材料，由碳纳米管和包覆在所述碳纳米管外的碳层组成，碳层中嵌有贵金属纳米粒子，有效防止了催化氧化还原反应过程中的高酸性、高电压对内层碳纳米管的强烈腐蚀，使催化剂保持良好的导电性能，提高了催化剂的耐腐蚀稳定性和催化活性，不过，其成本高，制备工艺复杂，催化剂不具备良好的耐水热性能。
发明内容
本发明的目的是克服NiSn纳米催化剂活性组分颗粒分散性差、耐水热性能 差的缺陷和不足，提供一种嵌入式耐水热NiSn-CS纳米催化剂的制备方法，通过将Ni盐、Sn盐和壳聚糖混合形成溶胶溶液，除去溶剂得到凝胶，再碳化处理制得嵌入式耐水热NiSn-CS纳米催化剂。
本发明的另一目的是提供一种嵌入式耐水热NiSn-CS纳米催化剂。
本发明的又一目的是嵌入式耐水热NiSn-CS纳米催化剂在小分子醇合成高碳醇中的应用。
本发明上述目的通过以下技术方案实现：
一种嵌入式耐水热NiSn-CS纳米催化剂的制备方法，包括以下步骤：
S1.将Ni盐、Sn盐和壳聚糖溶解形成溶胶溶液；
S2.将S1中的溶胶溶液除去溶剂得到凝胶，再将其在惰性氛围中碳化处理，获得嵌入式耐水热NiSn-CS纳米催化剂；
其中，碳化温度为400～600℃，碳化时间为1～4h。
其中，步骤S1中的溶胶溶液可按以下方法制备：将Ni盐、Sn盐和壳聚糖溶解于1～5wt％乙酸水溶液中，60～90℃加热搅拌，搅拌转速为300～1000rpm，壳聚糖完全溶解后形成溶胶溶液。
步骤S2中溶胶溶液的干燥温度为40～70℃，优选为50℃；碳化温度优选为500℃，碳化温度过低会导致壳聚糖碳化不充分，金属活性位点暴露不完全，碳化温度过高易造成金属纳米粒子团聚长大，从而影响催化剂的催化活性。
碳化时间过短会导致壳聚糖碳化不充分，金属离子无法被完全还原，金属活性位点减少；碳化时间过长，会破坏碳层的结构，并造成金属粒子团聚长大，从而影响催化剂的催化活性。
优选地，步骤S1中的壳聚糖的Mw为700～250000。
优选地，步骤S1中的壳聚糖的Mw为100000～150000。
壳聚糖中有羟基、氨基、羧基多种基团可与Ni离子、Sn离子进行螯合，有利于催化剂中NiSn活性位点的生成和分散，同时包覆于NiSn纳米粒子表面形成耐水热的催化剂结构。
优选地，步骤S1中Ni盐和Sn盐的摩尔比为1：(0.03～0.24)。
Ni盐与Sn盐的优选摩尔比为1：0.06。
优选地，步骤S1中Ni盐和Sn盐的混合物与壳聚糖的摩尔比为1：(0.2～2)。
优选地，步骤S1中Ni盐和Sn盐的混合物与壳聚糖的摩尔比为1：(1～1.5)。
Ni盐和Sn盐的混合物与壳聚糖的摩尔比过小，导致催化剂的金属活性位点数量过少，催化剂性能较差；Ni盐和Sn盐的混合物与壳聚糖的摩尔比过大，壳聚糖不能充分还原金属离子，以及NiSn纳米粒子无法完全嵌入碳层，从而降低催化剂的活性。
一种由上述制备方法制备的嵌入式耐水热NiSn-CS纳米催化剂。
本发明制备的嵌入式耐水热NiSn-CS纳米催化剂可应用于催化小分子醇合成高碳醇。
优选地，催化条件为NiSn-CS纳米催化剂：无机碱：小分子醇：水的质量比为1：(1～4)：(10～43)：(10～43)，催化反应温度为200～250℃，压力为0.1～2Mpa，更优选的催化条件为NiSn-CS纳米催化剂：无机碱：小分子醇：水的质量比为1：3：33：33，催化反应温度为230℃，压力为0.1Mpa。
与现有技术相比，本发明的有益效果是：
本发明提供一种嵌入式耐水热NiSn-CS纳米催化剂，该催化剂中的NiSn纳米粒子均匀于分布于碳层上，显著提高了NiSn催化活性中心的分散性及其在水热环境中的结构和活性的稳定性，应用于小分子醇合成高碳醇时，循环催化5次后，其结构基本保持不变，乙醇转化率依然高达65.7％(第一次66.3％)，C4+高碳醇选择性达到83.4％，表现出优异的催化效率和耐水热性能，且易于分离回收、污染小，具有优异的循环利用性。
本发明的制备方法无需经过复杂的前期处理，制备工艺简单。
附图说明
图1为本发明实施例4中嵌入式耐水热NiSn-CS纳米催化剂的SEM图；
图2为本发明实施例4中嵌入式耐水热NiSn-CS纳米催化剂在不同放大倍数下的TEM图；
图3为本发明实施例4中嵌入式耐水热NiSn-CS纳米催化剂循环催化5次后的TEM图；
图4为本发明对比例3中嵌入式耐水热NiSn-CS纳米催化剂的TEM图；
图5为本发明实施例6中嵌入式耐水热NiSn-CS纳米催化剂的TEM图；
图6为本发明对比例2中嵌入式耐水热NiSn-CS纳米催化剂的TEM图；
图7为本发明实施例1～5中嵌入式耐水热NiSn-CS纳米催化剂的XRD图。
具体实施方式
下面结合具体实施方式对本发明作进一步的说明，但实施例并不对本发明做任何形式的限定。除非另有说明，本发明实施例采用的原料试剂为常规购买的原料试剂。
实施例1
一种嵌入式耐水热NiSn-CS纳米催化剂的制备方法包括如下步骤：
S1.将一定量的Ni(NO 3) 2·6H 2O、SnCl 4·5H 2O和壳聚糖(Mw：700～1000)同时加入乙酸的水溶液中，搅拌形成均质溶胶，其中，各物质质量比如下：Ni(NO 3) 2·6H 2O：SnCl 4·5H 2O：壳聚糖：乙酸：水＝1.84：0.055：1：0.63：50，即金属前驱体(Ni盐和Sn盐的混合物)与壳聚糖单体的摩尔比为1：1；
S2.将步骤S1得到的溶胶溶液转移到50℃的干燥箱中干燥48h，得到NiSn-CS纳米催化剂前驱体，再将催化剂前驱体在N 2氛围中500℃碳化处理2h得到嵌入式耐水热NiSn-CS纳米催化剂。
实施例2
一种嵌入式耐水热NiSn-CS纳米催化剂的制备方法，包括如下步骤：
S1.将一定量的Ni(NO 3) 2·6H 2O、SnCl 4·5H 2O和壳聚糖(Mw：50000)同时加入乙酸的水溶液中，搅拌形成均质溶胶，其中，各物质质量比如下：Ni(NO 3) 2·6H 2O：SnCl 4·5H 2O：壳聚糖：乙酸：水＝1.84：0.66：1：0.63：50，即金属前驱体(Ni盐、Sn盐混合物)与壳聚糖单体的摩尔比为1：1；
S2.将步骤S1得到的溶胶溶液转移到50℃的干燥箱中干燥48h，得到NiSn-CS纳米催化剂前驱体，再将催化剂前驱体在N 2氛围中500℃碳化处理2h得到嵌入式耐水热NiSn-CS纳米催化剂。
实施例3
一种嵌入式耐水热NiSn-CS纳米催化剂的制备方法，包括如下步骤：
S1.将一定量的Ni(NO 3) 2·6H 2O、SnCl 4·5H 2O和壳聚糖(Mw：100000)同时加入乙酸的水溶液中，搅拌形成均质溶胶，其中，各物质质量比如下：Ni(NO 3) 2·6H 2O：SnCl 4·5H 2O：壳聚糖：乙酸：水＝1.84：0.11：1：0.63：50，即金属前驱体(Ni盐和Sn盐的混合物)与壳聚糖单体的摩尔比为1：1；
S2.将步骤S1得到的溶胶溶液转移到50℃的干燥箱中干燥48h，得到NiSn-CS纳米催化剂前驱体，再将催化剂前驱体在N 2氛围中500℃碳化处理2h得到嵌入式耐水热NiSn-CS纳米催化剂。
实施例4～5
实施例4步骤S1中的壳聚糖的Mw为150000，其他同实施例3。
实施例5步骤S1中的壳聚糖的Mw为250000，其他同实施例3。
实施例6～7
实施例6步骤S2中的碳化处理温度为400℃，其他同实施例4。
实施例7步骤S2中的碳化处理温度为600℃，其他同实施例4。
实施例8～9
实施例8步骤S2中的碳化处理时间为1h，其他同实施例4。
实施例9步骤S2中的碳化处理时间为4h，其他同实施例4。
实施例10～12
实施例10步骤S1中的Ni盐、Sn盐混合物与壳聚糖的摩尔比为1：1.5，其他同实施例4。
实施例11步骤S1中的Ni盐、Sn盐混合物与壳聚糖的摩尔比为1：2，其他同实施例4。
实施例12步骤S1中的Ni盐、Sn盐混合物与壳聚糖的摩尔比为1：0.2，其他同实施例4。
对比例1～2
对比例1步骤S2中的碳化处理温度为300℃，其他同实施例4。
对比例2步骤S2中的碳化处理温度为700℃，其他同实施例4。
对比例3
一种NiSn纳米催化剂的制备方法包括如下步骤：
S1.将一定量的Ni(NO 3) 2·6H 2O、SnCl 4·5H 2O同时加入乙酸水溶液中，搅拌形成均匀溶液，其中，各物质质量比如下Ni(NO 3) 2·6H 2O：SnCl 4·5H 2O：乙酸：水＝1.84：0.11：0.63：50；
S2.将步骤S1中均匀溶液转移到50℃的干燥箱中干燥48h，得到NiSn纳米催化剂前驱体，再将催化剂前驱体在N 2氛围中500℃碳化处理2h得到NiSn纳米催化剂。
表1 各实施例及对比例汇总
Figure PCTCN2021127576-appb-000001
Figure PCTCN2021127576-appb-000002
结果检测
(1)SEM和TEM测试
图1和图2分别是实施例4中NiSn-CS纳米催化剂的SEM图及不同放大倍数的TEM图，从SEM图中可看出制得催化剂呈镶嵌结构，碳包裹着NiSn纳米颗粒镶嵌在碳薄层上，粒子的直径小且分散性好。图3为实施例4制得产物循环催化5次后的TEM图，与反应前的结构(图2)相比，可以看出该催化剂结构稳定。图4为对比例3制得产物的TEM图，NiSn纳米颗粒较大且粒子团聚严重。图5为实施例6制得产物的TEM图，催化剂中NiSn纳米颗粒较大且碳层较厚。图6为对比例2制得产物的TEM图，催化剂中NiSn纳米颗粒的粒径较大，易发生聚集，分散度较差，反应活性低。
(2)XRD测试
本发明实施例1～5制得产物的XRD如图7所示，随着壳聚糖分子量增大，金属Ni与NiSn-CS的特征衍射峰逐渐增强，NiSn-CS在催化过程中起了决定性作用，说明壳聚糖作为碳源的碳壳层有利于实现金属中心的稳定性；但壳聚糖分 子量持续增大时，金属Ni和NiSn-CS的晶型相慢慢减弱。
(3)催化剂催化性能测试
具体测试方法：将实施例1～12和对比例1～3制得产物在70mL钢制磁力搅拌反应釜中与均相碱(NaOH)协同催化乙醇碳-碳偶联合成高级燃料醇反应，其中，催化剂：NaOH：乙醇：水的质量比为1：3：33：33，反应温度230℃、起始压力为0.1MPa，反应时长12h，反应结束后使反应釜冷却至室温，进行离心、过滤，得到液相和催化剂固相，收集气相和液相产物，液相产物离心后静置，可加速自发相分层得到有机相和水相，液相产物离心分离后通过气相色谱进行检测分析，有机相主要产物即为C4+高碳醇。取上述实施例4所制备的催化剂，重新在磁力搅拌反应釜中与均相碱(NaOH)协同催化乙醇碳-碳偶联合成高级燃料醇反应，反应条件同上，如此循环4次。
表2 各实施例及对比例所制得产物的催化活性结果
Figure PCTCN2021127576-appb-000003
由实施例1～5可知，在制备过程中，随着壳聚糖分子量的增加，所制得催化剂催化合成高碳醇效果呈现先递增后递减的趋势，这可能与包裹在NiSn纳米颗粒表面的碳壳层厚度有关，适当的碳壳层厚度有利于保护催化剂金属核心，增强其在水热反应环境下的催化稳定性，从而提升乙醇的转化率及液相生成的选择性。当壳聚糖分子量继续增加时，使得碳壳层的厚度持续增加，不利于反应中水相与催化剂金属活性核心的物质传递，乙醇的转化率出现下滑。
由实施例4和实施例6～7及对比例1～2可知，碳化温度过低会导致壳聚糖碳化不充分，金属活性位点暴露不完全；碳化温度过高，则易造成金属粒子团聚长大，从而影响催化剂的催化活性。其中，碳化温度为500℃时所制备的嵌入式耐水热NiSn-CS纳米催化剂具有更优的催化活性。
由实施例4和实施例8～9可看出，碳化时间过短会导致壳聚糖碳化不充分，金属离子无法被完全还原，金属活性位点减少；碳化时间过长，会破坏碳层的结构，并造成金属粒子团聚长大，从而影响催化剂的催化活性。其中，碳化时间为2h时所制备的嵌入式耐水热NiSn-CS纳米催化剂具有更优的催化活性。
由实施例4和实施例10～12可看出，Ni盐和Sn盐的混合物与壳聚糖的摩尔比过小，导致催化剂的金属活性位点数量过少，催化剂性能较差；Ni盐和Sn盐的混合物与壳聚糖的摩尔比过大，壳聚糖不能充分还原金属离子，以及NiSn纳米颗粒无法完全嵌入碳层，从而降低催化剂的活性。其中，Ni盐和Sn盐的混合物与壳聚糖的摩尔比为1：1时所制备的嵌入式耐水热NiSn-CS纳米催化剂具有更优的催化活性。
本发明制得的催化剂在催化乙醇合成C4+高碳醇反应中表现优异，乙醇转化率最高达到66.3％，C4+高碳醇选择性达到85.1％。
表3 实施例4制得的催化剂第1、3、5次的催化活性结果
Figure PCTCN2021127576-appb-000004
实施例4所制得的催化剂在催化乙醇合成C4+高碳醇反应中的催化活性结果如表3所示，由表中数据可看出，其催化性能稳定，循环催化至第5次时，乙醇转化率依然高达65.7％，C4+高碳醇选择性达到83.4％。
显然，本发明的上述实施例仅仅是为清楚地说明本发明所作的举例，而并非是对本发明的实施方式的限定。对于所属领域的普通技术人员来说，在上述说明的基础上还可以做出其它不同形式的变化或变动。这里无需也无法对所有的实施方式予以穷举。凡在本发明的精神和原则之内所作的任何修改、等同替换和改进等，均应包含在本发明权利要求的保护范围之内。

Claims (10)

  1. 一种嵌入式耐水热NiSn-CS纳米催化剂的制备方法，其特征在于，包括以下步骤：
    S1.将Ni盐、Sn盐和壳聚糖(C 6H 11NO 4) n溶解形成溶胶溶液；
    S2.将S1中的溶胶溶液除去溶剂得到凝胶，再将其在惰性氛围中碳化处理，获得嵌入式耐水热NiSn-CS纳米催化剂；
    其中，碳化温度为400～600℃，碳化时间为1～4h。
  2. 如权利要求1所述嵌入式耐水热NiSn-CS纳米催化剂的制备方法，其特征在于，S1中所述壳聚糖的Mw为700～250000。
  3. 如权利要求2所述嵌入式耐水热NiSn-CS纳米催化剂的制备方法，其特征在于，S1中所述壳聚糖的Mw为100000～150000。
  4. 如权利要求1所述嵌入式耐水热NiSn-CS纳米催化剂的制备方法，其特征在于，S1中所述Ni盐和Sn盐的摩尔比为1：(0.03～0.24)。
  5. 如权利要求1所述嵌入式耐水热NiSn-CS纳米催化剂的制备方法，其特征在于，S1中所述Ni盐和Sn盐的混合物与壳聚糖的摩尔比为1：(0.2～2)。
  6. 如权利要求5所述嵌入式耐水热NiSn-CS纳米催化剂的制备方法，其特征在于，S1中所述Ni盐和Sn盐的混合物与壳聚糖的摩尔比为1：(1～1.5)。
  7. 如权利要求1所述嵌入式耐水热NiSn-CS纳米催化剂的制备方法，其特征在于，碳化温度为500℃，碳化时间为2h。
  8. 一种权利要求1～7任一项所述嵌入式耐水热NiSn-CS纳米催化剂的制备方法制得的催化剂。
  9. 如权利要求8所述嵌入式耐水热NiSn-CS纳米催化剂在催化小分子醇合成高碳醇中的应用。
  10. 如权利要求9所述嵌入式耐水热NiSn-CS纳米催化剂在催化小分子醇合成高碳醇中的应用，其特征在于，NiSn-CS纳米催化剂：无机碱：小分子醇：水的质量比为1：(1～4)：(10～43)：(10～43)，催化反应温度为200～270℃，压力为0.1～2MPa。
PCT/CN2021/127576 2021-08-26 2021-10-29 一种嵌入式耐水热NiSn-CS纳米催化剂及其制备方法和应用 WO2023024254A1 (zh)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
CN202110991336.9A CN115722230A (zh) 2021-08-26 2021-08-26 一种嵌入式耐水热NiSn-CS纳米催化剂及其制备方法和应用
CN202110991336.9 2021-08-26

Publications (1)

Publication Number Publication Date
WO2023024254A1 true WO2023024254A1 (zh) 2023-03-02

Family

ID=85290082

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/CN2021/127576 WO2023024254A1 (zh) 2021-08-26 2021-10-29 一种嵌入式耐水热NiSn-CS纳米催化剂及其制备方法和应用

Country Status (2)

Country Link
CN (1) CN115722230A (zh)
WO (1) WO2023024254A1 (zh)

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2010269284A (ja) * 2009-05-25 2010-12-02 Kyocera Chemical Corp 炭素基材担体触媒の製造方法及び炭素基材担体触媒
CN104538595A (zh) * 2014-12-10 2015-04-22 南京师范大学 嵌入式纳米金属负载型碳纳米片锂离子电池负极材料及其制备方法和应用
WO2017207555A1 (en) * 2016-05-31 2017-12-07 Studiengesellschaft Kohle Mbh Preparation of mesoporous carbon with catalytically active metal oxide nanoparticles for the selective hydrogenation of alpha-beta-unsaturated aldehydes
CN107895783A (zh) * 2017-11-13 2018-04-10 南京师范大学 一种柔性碳膜包覆无定型Sn‑Ni‑P三明治结构纳米材料及其制备方法和应用
CN112973707A (zh) * 2021-02-26 2021-06-18 广东工业大学 一种NiSn/C核壳形复合纳米催化剂及其制备方法和应用

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2010269284A (ja) * 2009-05-25 2010-12-02 Kyocera Chemical Corp 炭素基材担体触媒の製造方法及び炭素基材担体触媒
CN104538595A (zh) * 2014-12-10 2015-04-22 南京师范大学 嵌入式纳米金属负载型碳纳米片锂离子电池负极材料及其制备方法和应用
WO2017207555A1 (en) * 2016-05-31 2017-12-07 Studiengesellschaft Kohle Mbh Preparation of mesoporous carbon with catalytically active metal oxide nanoparticles for the selective hydrogenation of alpha-beta-unsaturated aldehydes
CN107895783A (zh) * 2017-11-13 2018-04-10 南京师范大学 一种柔性碳膜包覆无定型Sn‑Ni‑P三明治结构纳米材料及其制备方法和应用
CN112973707A (zh) * 2021-02-26 2021-06-18 广东工业大学 一种NiSn/C核壳形复合纳米催化剂及其制备方法和应用

Also Published As

Publication number Publication date
CN115722230A (zh) 2023-03-03

Similar Documents

Publication Publication Date Title
WO2022178959A1 (zh) 一种NiSn/C核壳形复合纳米催化剂及其制备方法和应用
Ruiz-Camacho et al. Pt supported on mesoporous material for methanol and ethanol oxidation in alkaline medium
Huang et al. Synthesis and structural characterization of silica dispersed copper nanomaterials with unusual thermal stability prepared by precipitation-gel method
CN110433853B (zh) 一种改性介孔分子筛负载铂基催化剂及其制备方法
CN110813363B (zh) 一种氮硫掺杂多孔碳改性碳纳米管担载Pt-Ni合金催化剂及其制备方法
CN103301841B (zh) 一种石墨烯负载高分散纳米Ni催化剂及其制备方法和应用
JP2008251413A (ja) 金属酸化物担持カーボンの製造方法
CN107282079B (zh) 一种带状碳化钒电催化剂的制备方法及产品
Lin et al. Carbohydrate-derived porous carbon materials: An ideal platform for green organic synthesis
CN107088415B (zh) 一种铂合金纳米粉末催化剂的制备方法
WO2021120928A1 (zh) 一种制备Ni-X基氧化物催化剂的方法及其在转移加氢中的应用
CN108579750B (zh) 一种铜掺杂Ni/SiO2纳米复合催化剂及其制备方法
CN108658038B (zh) 一种基于LiAlH4的储氢材料及其制备方法
Li et al. Crystalline nickel boride nanoparticle agglomerates for enhanced electrocatalytic methanol oxidation
CN110534754B (zh) 一种包裹Fe3C纳米晶的碳纳米管及其制备方法和应用
Zhang et al. Preparation of Heteroatom‐Doped Carbon Materials and Applications in Selective Hydrogenation
CN113235108B (zh) 一种MXene负载贵金属团簇催化剂及其制备方法和应用
WO2023024254A1 (zh) 一种嵌入式耐水热NiSn-CS纳米催化剂及其制备方法和应用
de Yuso et al. Optimization of the synthesis of Pd-Au nanoalloys confined in mesoporous carbonaceous materials
CN115283007B (zh) 铂金属纳米团簇ha分子筛的制备及其在1,2,3,4-四氢喹啉合成中的应用
CN115647382B (zh) 一种铂纳米棒的制备方法及其在燃料电池催化剂中的应用
JP2003320249A (ja) 金属担持触媒並びにその製造方法及びこれを利用する固体高分子電解質型燃料電池
CN108091890B (zh) 一种基于银-钴-鸟嘌呤纳米片状材料的制备方法
CN108777311B (zh) 一种具有高氧化还原电催化活性的Pd/MGN复合材料及其制备方法和应用
KR102098066B1 (ko) 고활성 전극 촉매의 제조방법 및 그를 이용하여 제조된 고활성 전극 촉매

Legal Events

Date Code Title Description
121 Ep: the epo has been informed by wipo that ep was designated in this application

Ref document number: 21954774

Country of ref document: EP

Kind code of ref document: A1

NENP Non-entry into the national phase

Ref country code: DE