A catalyst for the synthesis of advanced alcohols that can be blended with marine fuels, its preparation method and application

Abstract

This invention proposes a catalyst for the synthesis of higher alcohols that can be blended with marine fuels, its preparation method, and its application, belonging to the field of catalyst technology. Nickel salt and bismuth salt are dissolved in deionized water and stirred to form a homogeneous solution. CeO2 is added to the homogeneous solution and stirred, then dried to obtain a precursor. The precursor is calcined under an inert atmosphere to obtain the catalyst for the synthesis of higher alcohols that can be blended with marine fuels. This catalytic system achieves significant optimization of reaction conditions through carefully designed metal-support interactions, enabling the catalyst to maintain high activity while significantly improving the selectivity for long-chain alcohol products. Furthermore, the controllable oxygen vacancies on the CeO2 support surface in this catalyst not only stabilize reaction intermediates and remove surface carbon, ensuring the long-term recycling of the catalyst, but also facilitate separation, recovery, and reuse during the preparation of higher alcohols.

Description

Technical Field

[0001] This invention belongs to the field of catalyst technology, and particularly relates to a catalyst for the synthesis of advanced alcohols that can be blended with marine fuels, its preparation method, and its application. Background Technology

[0002] Methanol is one of the most critical organic raw materials in the modern coal chemical industry, playing a vital supporting role as a fundamental material. In nature, water is photolyzed by sunlight to produce hydrogen, which then combines with carbon dioxide in the air to form methanol. The synthesis process produces almost zero carbon emissions, achieving both energy conservation and emission reduction. Furthermore, like ethanol, methanol can be used as a fuel for internal combustion engines, alleviating my country's current energy and chemical raw material shortages. In the shipping industry, using methanol as a power fuel can reduce nitrogen oxide emissions by 80% and sulfur oxide emissions by 99%, and can reduce carbon dioxide emissions by up to 25%, making it considered an environmentally friendly alternative to LNG for marine fuels.

[0003] Currently, the developed alternative biomass fuels are mainly used in blends with traditional fuels. However, there are still significant differences in the physicochemical properties of traditional fuels and small-molecule methanol and ethanol, leading to problems in blending ratios and storage and transportation. Higher alcohols (such as n-butanol, isoamyl alcohol, n-hexanol, and isohexanol) have energy densities closer to diesel fuel, while also possessing advantages such as low corrosivity and convenient storage and transportation. Furthermore, the physicochemical properties of higher alcohols, such as calorific value and cetane number, are similar to diesel fuel, allowing for blending with diesel in any proportion. Therefore, higher alcohols represent a highly promising high-quality biomass-based fuel. Blending higher alcohols with diesel fuel for ship propulsion can not only solve the cost problem of methanol dual-fuel propulsion systems but also significantly reduce fuel storage tank space, resulting in substantial advantages in ship transportation costs and the scale of refueling stations.

[0004] The conversion of methanol and ethanol to higher alcohols can be achieved through the Guerbet coupling reaction. The cross-coupling mainly includes three steps: (1) methanol dehydrogenates to formaldehyde and ethanol dehydrogenates to acetaldehyde; (2) aldehyde and alcohol condense and lose a water molecule to obtain an alkenal; (3) the alkenal is hydrogenated to generate the coupled alcohol.

[0005] In the field of alcohol catalytic coupling, existing catalytic systems still face several key challenges, which severely restrict the economic efficiency and feasibility of this technology in industrial applications. Traditional transition metal catalysts typically require high reaction temperatures to achieve effective C-C coupling. These demanding reaction conditions not only lead to excessive energy consumption but also trigger a series of side reactions, such as alcohol dehydration to olefins and excessive dehydrogenation to aldehydes and ketones. Even more challenging is the limited selectivity of most catalytic systems for the target product, making it difficult to achieve the targeted synthesis of products with specific carbon chain lengths. Summary of the Invention

[0006] To overcome the problem that existing catalysts require high reaction temperatures for the synthesis of higher alcohols from small molecules in aqueous phase, this invention proposes a catalyst for the synthesis of higher alcohols that can be blended with marine fuels, as well as its preparation method and application.

[0007] To achieve the above objectives, the present invention provides the following technical solution:

[0008] One of the technical solutions of the present invention:

[0009] A method for preparing a catalyst for the synthesis of higher alcohols that can be blended with marine fuels includes the following steps:

[0010] Nickel salt and bismuth salt are dissolved in deionized water and stirred to form a homogeneous solution;

[0011] CeO2 was added to the homogeneous solution and stirred, then dried to obtain the precursor;

[0012] The precursor is calcined under an inert atmosphere to obtain the advanced alcohol synthesis catalyst that can be blended with marine fuel.

[0013] Further, the molar ratio of the nickel salt to the bismuth salt is (1-4):4; preferably, the molar ratio of the nickel salt to the bismuth salt is 1:2.

[0014] Further, the molar ratio of the nickel salt to CeO2 is (1-4):4; preferably, the molar ratio of the nickel salt to CeO2 is 1:2.

[0015] Further, the roasting temperature is 300-600℃ and the roasting time is 1-3h; preferably, the roasting temperature is 550℃ and the roasting time is 2h.

[0016] Nickel salts conventional in the art can be used in this invention. Preferably, the nickel salt is selected from nickel nitrate.

[0017] Commonly used bismuth salts in the art can be used in this invention. Preferably, the nickel salt is selected from bismuth nitrate.

[0018] The second technical solution of the present invention:

[0019] A catalyst for the synthesis of advanced alcohols that can be blended with marine fuels, prepared by the above method.

[0020] The third technical solution of the present invention:

[0021] Application of the above-mentioned catalyst for the synthesis of higher alcohols that can be blended with marine fuel in the aqueous phase synthesis of higher alcohols from small molecule alcohols.

[0022] Furthermore, the small molecule alcohol is methanol and ethanol, and the higher alcohol is an alcohol with 5 to 16 carbon atoms.

[0023] More specifically, a method for the aqueous-phase synthesis of higher alcohols from small molecule alcohols using a catalyst that can be blended with marine fuel includes the following steps:

[0024] The above-prepared advanced alcohol synthesis catalyst for blendable marine fuel, sodium hydroxide, methanol, ethanol, and water were mixed in a reaction vessel at a mass ratio of 1:1:(10-40):(10-40):(10-40). After leak testing, the air inside the vessel was replaced with high-purity hydrogen. The reaction was carried out continuously for 20 hours at a reaction temperature of 180℃, an initial pressure of 0.2 MPa, and a stirring speed of 2000 rpm. After the reaction, the substrate spontaneously separated into oil and water phases. After centrifugation, the oil and water phases were analyzed by gas chromatography.

[0025] The advanced alcohol synthesis catalyst for blendable marine fuels of this invention significantly reduces the methanol-ethanol coupling reaction temperature through the synergistic effect of multiple components. Its core mechanism lies in the fact that controllable oxygen vacancies on the CeO2 surface can efficiently activate the OH bond of alcohol molecules at low temperatures to generate key alkoxy intermediates. At the same time, the Ni-Bi bimetallic components form a unique electron transfer channel through CeO2 bridging. The electron-rich characteristics of Ni sites promote the polarization and breaking of CH bonds, while the electron-deficient state of Bi sites effectively inhibits the β-H elimination side reaction. This combination of electron synergy between metal and support and the intrinsic activation ability of oxygen vacancies not only lowers the activation energy barrier of CC coupling, but also achieves high selectivity conversion under low temperature conditions by stabilizing reaction intermediates, ultimately reducing the reaction temperature window by 70-100℃ compared with traditional catalysts.

[0026] Compared with the prior art, the present invention has the following advantages and technical effects:

[0027] (1) The advanced alcohol synthesis catalyst for blendable marine fuels developed in this invention exhibits unique advantages. This catalytic system achieves significant optimization of reaction conditions through carefully designed metal-support interactions. Specifically, the tunable oxygen vacancies on the CeO2 support surface not only significantly reduce the activation energy and required reaction temperature but also provide crucial intermediate stabilization; while the Ni-Bi bimetallic component precisely regulates the selectivity of CH bond activation and CC coupling through electronic synergistic effects. This multi-component synergistic mechanism enables the catalyst to maintain high activity while significantly improving the selectivity for long-chain alcohol products.

[0028] (2) The advanced alcohol synthesis catalyst for blendable marine fuel developed in this invention exhibits excellent stability. The tunable oxygen vacancies on the CeO2 support surface not only stabilize the reaction intermediates but also potentially oxidize carbon deposits into volatile substances such as CO or CO2 by adsorbing and activating oxygen-containing species in the reaction, thereby removing surface carbon deposits and ensuring the long-term recycling of the catalyst. These innovative designs provide new ideas for solving key scientific problems in alcohol coupling reactions and lay an important foundation for the development of related industrial processes.

[0029] (3) The advanced alcohol synthesis catalyst of the present invention that can be blended with marine fuel is a heterogeneous catalyst, which is easy to separate, recover and reuse during the preparation of advanced alcohols. Attached Figure Description

[0030] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0031] Figure 1 The image shows the XRD pattern of the NiBi-CeO2 ternary catalyst prepared in Example 1. Detailed Implementation

[0032] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0033] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Every smaller range between any stated value or intermediate value within a stated range, and any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0034] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0035] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be apparent to those skilled in the art. This specification and embodiments are merely exemplary.

[0036] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0037] This invention provides a method for preparing a catalyst for the synthesis of higher alcohols that can be blended with marine fuels, comprising the following steps:

[0038] (1) Dissolve nickel salt and bismuth salt in deionized water and stir to form a homogeneous solution;

[0039] (2) Add CeO2 to the homogeneous solution and stir, then dry to obtain the precursor;

[0040] (3) The precursor is calcined in an inert atmosphere to obtain a high alcohol synthesis catalyst that can be blended with marine fuel (denoted as NiBi-CeO2 ternary catalyst).

[0041] In a preferred embodiment of the present invention, the molar ratio of nickel salt to bismuth salt is (1-4):4; more preferably, the molar ratio of nickel salt to bismuth salt is 1:2.

[0042] In a preferred embodiment of the present invention, the molar ratio of nickel salt to CeO2 is (1-4):4; more preferably, the molar ratio of nickel salt to CeO2 is 1:2.

[0043] In a preferred embodiment of the present invention, the roasting temperature is 300-600°C and the roasting time is 1-3 hours; more preferably, the roasting temperature is 550°C and the roasting time is 2 hours.

[0044] In a preferred embodiment of the present invention, the stirring in step (2) is: stirring at 40 to 100°C for 1 to 6 hours; more preferably, stirring at 70°C for 2 hours.

[0045] Nickel salts are conventionally used in this invention. Preferably, the nickel salt is selected from nickel nitrate.

[0046] Bismuth salts are conventionally used in this invention. Preferably, the nickel salt is selected from bismuth nitrate.

[0047] This invention also proposes an advanced alcohol synthesis catalyst that can be blended with marine fuel, prepared by the above-described method.

[0048] The advanced alcohol synthesis catalyst for blending marine fuel prepared in this invention can be used to catalyze the aqueous phase synthesis of advanced alcohols from small molecule alcohols. During the catalytic reaction, the small molecule alcohols are methanol and ethanol, and the advanced alcohols are alcohols with 5 to 16 carbon atoms (i.e., C5+ advanced alcohols). More specifically, the method for catalyzing the aqueous phase synthesis of advanced alcohols from small molecule alcohols using the advanced alcohol synthesis catalyst for blending marine fuel includes the following steps:

[0049] The above-prepared advanced alcohol synthesis catalyst for blending marine fuel, sodium hydroxide, methanol, ethanol, and water were mixed in a reaction vessel at a mass ratio of 1:1:(10-40):(10-40):(10-40). After leak testing, the air inside the vessel was replaced with high-purity hydrogen. The reaction was carried out continuously for 20 hours at a reaction temperature of 180℃, an initial pressure of 0.2MPa, and a stirring speed of 2000rpm. After the reaction, the substrate spontaneously separated into oil and water phases. The liquid and solid phase catalysts were obtained by centrifugation and filtration. After the liquid phase was allowed to stand, it naturally separated into oil and water phases. The oil phase product was an advanced alcohol.

[0050] All raw materials used in the embodiments of this invention were purchased commercially.

[0051] The technical solution of the present invention will be further illustrated by the following embodiments.

[0052] Example 1

[0053] A method for preparing a catalyst for the synthesis of higher alcohols that can be blended with marine fuels includes the following steps:

[0054] (1) Dissolve nickel nitrate and bismuth nitrate in deionized water and stir to form a homogeneous solution. The molar ratio of nickel nitrate to bismuth nitrate is 1:4, and the volume ratio of bismuth nitrate to deionized water is 0.01 mol: 15 mL.

[0055] (2) Add CeO2 to the homogeneous solution obtained in step (1), stir at 70°C for 2 hours and dry to obtain the precursor, wherein the molar ratio of nickel nitrate to CeO2 is 1:4;

[0056] (3) The precursor obtained in step (2) is placed in an inert atmosphere and calcined at 550°C for 2 hours to obtain an advanced alcohol synthesis catalyst (NiBi-CeO2 ternary catalyst) that can be blended with marine fuel.

[0057] Example 2

[0058] Same as Example 1, except that:

[0059] In step (1), the molar ratio of nickel nitrate to bismuth nitrate is 1:1 (i.e. 4:4);

[0060] In step (2), the molar ratio of nickel nitrate to CeO2 is 1:1 (i.e. 4:4);

[0061] The remaining steps are consistent with those in Example 1.

[0062] Example 3

[0063] Same as Example 1, except that:

[0064] In step (1), the molar ratio of nickel nitrate to bismuth nitrate is 1:2 (i.e. 2:4);

[0065] In step (2), the molar ratio of nickel nitrate to CeO2 is 1:2 (i.e. 2:4);

[0066] The remaining steps are consistent with those in Example 1.

[0067] Example 4

[0068] Same as Example 1, except that:

[0069] In step (1), the molar ratio of nickel nitrate to bismuth nitrate is 3:4;

[0070] In step (2), the molar ratio of nickel nitrate to CeO2 is 3:4;

[0071] The remaining steps are consistent with those in Example 1.

[0072] Example 5

[0073] Same as Example 1, except that:

[0074] In step (3), the precursor obtained in step (2) is placed in an inert atmosphere and calcined at 400°C for 2 hours;

[0075] The remaining steps are consistent with those in Example 1.

[0076] Example 6

[0077] Same as Example 1, except that:

[0078] In step (3), the precursor obtained in step (2) is placed in an inert atmosphere and calcined at 450°C for 2 hours;

[0079] The remaining steps are consistent with those in Example 1.

[0080] Example 7

[0081] Same as Example 1, except that:

[0082] In step (3), the precursor obtained in step (2) is placed in an inert atmosphere and calcined at 500°C for 2 hours;

[0083] The remaining steps are consistent with those in Example 1.

[0084] Example 8

[0085] Same as Example 1, except that:

[0086] In step (3), the precursor obtained in step (2) is placed in an inert atmosphere and calcined at 600°C for 2 hours;

[0087] The remaining steps are consistent with those in Example 1.

[0088] Example 9

[0089] Same as Example 1, except that:

[0090] In step (3), the precursor obtained in step (2) is placed in an inert atmosphere and calcined at 300°C for 3 hours;

[0091] The remaining steps are consistent with those in Example 1.

[0092] Example 10

[0093] Same as Example 1, except that:

[0094] In step (3), the precursor obtained in step (2) is placed in an inert atmosphere and calcined at 500°C for 1 hour;

[0095] The remaining steps are consistent with those in Example 1.

[0096] Comparative Example 1

[0097] Same as Example 1, except that the addition of bismuth nitrate is omitted. A method for preparing a higher alcohol synthesis catalyst includes the following steps:

[0098] (1) Dissolve nickel nitrate and CeO2 in deionized water and stir to form a homogeneous solution. The molar ratio of nickel nitrate to CeO2 is 1:4, and the volume ratio of bismuth nitrate to deionized water is 0.01 mol: 15 mL.

[0099] (2) Stir the homogeneous solution obtained in step (1) at 70°C for 2 hours and dry it to obtain the precursor;

[0100] (3) The precursor obtained in step (2) is placed in an inert atmosphere and calcined at 550°C for 2 hours to obtain a catalyst for the synthesis of higher alcohols.

[0101] Comparative Example 2

[0102] Same as Example 1, except that the addition of nickel nitrate is omitted. A method for preparing a higher alcohol synthesis catalyst includes the following steps:

[0103] (1) Dissolve bismuth nitrate and CeO2 in deionized water and stir to form a homogeneous solution. The molar ratio of bismuth nitrate to CeO2 is 1:4, and the volume ratio of bismuth nitrate to deionized water is 0.01 mol: 15 mL.

[0104] (2) Stir the homogeneous solution obtained in step (1) at 70°C for 2 hours and dry it to obtain the precursor;

[0105] (3) The precursor obtained in step (2) is placed in an inert atmosphere and calcined at 550°C for 2 hours to obtain a catalyst for the synthesis of higher alcohols.

[0106] Performance testing

[0107] (1) XRD analysis

[0108] The XRD pattern of the NiBi-CeO2 ternary catalyst prepared in Example 1 is shown in [reference needed]. Figure 1 As can be seen, CeO2, acting as a support, exhibits high diffraction peak intensities, indicating a high content and good dispersion of CeO2 in the material. This may mean that CeO2 has successfully formed a stable crystal structure within the material. The high diffraction peak intensities of Ni indicate high crystallinity and good dispersion on the CeO2 support, suggesting that Ni is successfully loaded onto the CeO2 support and uniformly distributed. Although the diffraction peaks of Bi are relatively low in intensity, they are still clearly visible, indicating that Bi is also successfully loaded onto the CeO2 support and has a certain degree of dispersion. In summary, in the NiBi-CeO2 ternary catalyst system, CeO2, as a support, provides stable structural support for Ni and Bi, enabling Ni and Bi to be successfully dispersed and loaded on its surface or within it.

[0109] The XRD patterns of the advanced alcohol synthesis catalysts that can be blended with marine fuels obtained in Examples 2-8 all showed Ni, Bi and CeO2 peaks.

[0110] (2) Catalysis experiment

[0111] The catalysts prepared in Examples 1-10 and Comparative Examples 1-2 were respectively added to a 70ml high-pressure reactor and co-catalyzed with a homogeneous base to produce higher alcohols via carbon-carbon cross-coupling of methanol and ethanol. Specifically, 0.5g of the higher alcohol synthesis catalyst, 0.5g of NaOH, 5g of methanol, 5g of ethanol, and 10g of water were added to the high-pressure reactor. After leak testing, the air in the reactor was replaced with high-purity hydrogen. The reaction was carried out continuously for 20 hours at a reaction temperature of 180℃, an initial pressure of 0.2MPa, and a stirring speed of 2000rpm. After the reaction, the reaction system was cooled to room temperature, and the gas phase was collected using a gas bag. The liquid phase product was removed from the reactor. The liquid and solid phase catalysts were separated by centrifugation and filtration. After standing, the liquid phase naturally separated into oil and water phases. The gas phase product, water phase, and oil phase were qualitatively and quantitatively analyzed by gas chromatography. The analytical results are shown in Table 1 below.

[0112] Table 1. Qualitative and quantitative analysis results for each example / comparative example.

[0113]

[0114]

[0115] As shown in Table 1, the higher alcohol synthesis catalysts prepared in Examples 1-10 by changing the ratio of soluble nickel salt to bismuth salt and CeO2, as well as the calcination temperature, can be used for the cross-coupling of methanol and ethanol to prepare higher alcohols, thereby reducing the reaction temperature and increasing the yield of C5+ higher alcohols. The catalyst prepared in Example 3 exhibited the best performance, achieving high levels of methanol and ethanol conversion, selectivity of C5+ higher alcohols in the liquid phase, and yield of C5+ higher alcohols. The experimental results of Comparative Examples 1 and 2 fully demonstrate the necessity of the bimetallic synergistic effect. In Comparative Example 1, although the introduction of Ni provided an active center for CH bond dissociation, the lack of electronic regulation by Bi resulted in excessive dehydrogenation activity at the Ni sites, leading to the formation of a large number of byproducts and accelerating catalyst deactivation due to carbon deposition. In Comparative Example 2, although the Bi / CeO2 system could partially suppress side reactions through the electronic effect of Bi, the lack of efficient CH bond activation by Ni significantly reduced the initial activation efficiency of the alcohol molecules. The limitations of this single-metal system are directly reflected in key performance indicators: the conversion rates of methanol and ethanol are significantly reduced, the selectivity of C5+ higher alcohols in the liquid phase products is insufficient, and ultimately the yield of C5+ higher alcohols is much lower than that of the NiBi-CeO2 ternary catalyst system formed in the examples.

[0116] The above are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. The application of a catalyst for the synthesis of higher alcohols that can be blended with marine fuel in the catalytic aqueous-phase synthesis of higher alcohols from small molecule alcohols, characterized in that, The small molecule alcohols are methanol and ethanol, and the higher alcohols are alcohols with 5 to 16 carbon atoms. The catalytic reaction temperature is 180°C and the time is 20 h. The preparation method of the advanced alcohol synthesis catalyst that can be blended with marine fuel includes the following steps: Nickel salt and bismuth salt are dissolved in deionized water and stirred to form a homogeneous solution; CeO2 was added to the homogeneous solution and stirred, then dried to obtain the precursor; The precursor is calcined under an inert atmosphere to obtain the advanced alcohol synthesis catalyst that can be blended with marine fuels. The molar ratio of nickel salt to bismuth salt is (1-4):4, and the molar ratio of nickel salt to CeO2 is (1-4):

4.

2. The application of the advanced alcohol synthesis catalyst blendable with marine fuel according to claim 1 in the catalytic aqueous-phase synthesis of advanced alcohols from small molecule alcohols, characterized in that, The molar ratio of the nickel salt to the bismuth salt is 1:

2.

3. The application of the advanced alcohol synthesis catalyst blendable with marine fuel according to claim 1 in the catalytic aqueous-phase synthesis of advanced alcohols from small molecule alcohols, characterized in that, The molar ratio of the nickel salt to CeO2 is 1:

2.

4. The application of the higher alcohol synthesis catalyst blendable with marine fuel according to claim 1 in the catalytic aqueous-phase synthesis of higher alcohols from small molecule alcohols, characterized in that, The roasting temperature is 300–600℃, and the roasting time is 1–3 hours.

5. The application of the advanced alcohol synthesis catalyst blendable with marine fuel according to claim 4 in the catalytic aqueous-phase synthesis of advanced alcohols from small molecule alcohols, characterized in that, The roasting temperature is 550℃ and the roasting time is 2 hours.

Images