Method for preparing liquid oxygen-containing fuel by catalyzing selective hydrogenolysis of lignin through one-step method

Abstract

The invention discloses a method for preparing liquid oxygen-containing fuel by catalyzing selective hydrogenolysis of lignin through a one-step method. The method comprises the following steps: by taking lignin as a raw material, adding a hydrated ruthenium-based modified molecular sieve catalyst and an alcohol solvent into the raw material, reacting for 2-6 hours at 210-290 DEG C under the H2 pressure of 1-4 MPa, and selectively depolymerizing the lignin to obtain the liquid oxygen-containing fuel, the formula of the hydrated ruthenium-based catalyst is HRO (at) CaTS. The conversion rate of the lignin reaches up to 98.5%, the total yield of volatile products reaches 46.0%, the yield of liquid oxygen-containing fuel products can reach 31.9%, and the selectivity reaches 69.5%. The catalyst used in the invention does not need additional reduction, the preparation process is simple, the environmental pollution is small, the efficient directional conversion of lignin is realized in a short preparation period, and the alcohol-based liquid oxygen-containing fuel with high selectivity and high added value is obtained.

Description

Technical Field

[0001] The present invention relates to a method for catalyzing lignin hydrogenolysis, in particular to a method for preparing liquid oxygen-containing fuel by catalyzing lignin selective hydrogenolysis in one step, belonging to the field of high-value utilization of renewable biomass. Background Art

[0002] Since the beginning of the 21st century, humanity's understanding of the energy crisis and environmental issues has deepened, prompting a pressing search for new, green energy sources to replace traditional fossil fuels. As the only renewable aromatic macromolecule, lignin holds enormous potential for biofuel production. However, lignin depolymerization products typically form complex, viscous, and acidic derivatives of phenolic compounds, making their direct utilization difficult. Therefore, converting lignin into saturated oxygenated fuels with stable properties and higher calorific value presents a more optimal value-added solution. Compared to fossil fuels, lignin-derived oxygenated fuels offer numerous advantages. Their relatively high oxygen content improves fuel efficiency and can reduce negative environmental impacts such as PM 2.5 and carbon monoxide emissions. Furthermore, saturated alcohols generally have good solubility and can be blended with a variety of fuel additives, enhancing overall fuel performance. Furthermore, oxygenated fuels derived from biomass are renewable and have low energy and environmental costs. Therefore, the value-added of lignin into saturated oxygenated fuels holds significant practical significance.

[0003] Lignin, the world's most abundant natural phenolic polymer, is composed of three basic structural units: p-coumaryl alcohol, coniferyl alcohol, and sinapyl alcohol. The proportions of these three monomers vary significantly in lignin from different plant sources: softwood lignin is dominated by coniferyl alcohol (90-95%), while hardwood lignin exhibits a binary dominance of coniferyl alcohol (25-50%) and sinapyl alcohol (50-75%). Herbaceous plant lignin typically contains all three structural units. Lignin is an aromatic, amorphous biomacromolecule with a high degree of polymerization, formed by random, disordered bonding of these structural units through CO and CC bonds. Its complex and highly cross-linked structure contains a rich variety of functional groups, including aliphatic hydroxyl groups, phenolic hydroxyl groups, and methoxyl groups. This makes lignin promising for broad applications in biomass conversion and materials science.

[0004] Reductive depolymerization, also known as catalytic hydrogenolysis, involves reducing lignin at 180-300°C in the presence of an external hydrogen source and a catalyst, promoting the breakage of CO and CC chemical bonds and thereby increasing the yield of soluble depolymerization products. Compared to other lignin depolymerization methods, catalytic hydrogenolysis offers advantages such as mild reaction conditions, concentrated distribution of depolymerization products, and low unsaturation, making it a highly promising lignin depolymerization method. The catalyst's pore structure and acidity / alkalinity significantly influence its hydrogenolysis activity for lignin. Molecular sieves are a highly performing and widely used catalyst, characterized by their high stability, regularly adjustable pore structure, abundant acid sites, and good product selectivity.

[0005] Chinese invention patent application CN118813294A discloses a method for producing a high-energy-density fuel using lignin oil as a single raw material. Using lignin oil as the single raw material, a core-shell catalyst is added and reacted under certain conditions to produce an oxygen-free fuel precursor. This technical embodiment involves adding 2.0 g of lignin sulfonate, 0.20 g of Ru / C, and 20 mL of methanol to a 100 mL stainless steel autoclave with an internal Teflon insert and mechanical stirring. The reaction is carried out at 3 MPa H₂ and 250°C for 12 hours to produce crude lignin oil. The mixture is then etherified in 10 mL of dimethyl carbonate in the presence of 100 mg of Cs₂CO₃ at 180°C for 3 hours. The solids are filtered, the solvent evaporated, and the polymer is extracted with petroleum ether to remove the polymer, producing lignin oil. The lignin oil obtained in this step is then used as the raw material for a catalytic reaction at 2-6 MPa H₂ pressure for 10-24 hours to ultimately produce the high-energy-density fuel. This technology requires a long reaction time under high pressure, and the reaction conditions are relatively harsh. At the same time, it is necessary to pre-treat lignin to obtain the reaction raw materials. The process is cumbersome and the preparation cycle is long, making it difficult to cater to rapid industrial applications.

[0006] Chinese invention patent application CN105152854A discloses a one-step method for converting lignin into liquid fuel. Lignin is used as the raw material, and a mixture of NaOH solution and a low-carbon alcohol is used as the composite reaction solvent. A depolymerization reaction is then carried out in the presence of a hydrogenation catalyst. After the reaction, the mixture is neutralized with HCl solution and filtered. Ethyl acetate is added to the filtrate, separating it into an aqueous phase and an oil phase. The oil phase is then subjected to rotary evaporation of the ethyl acetate to obtain a liquid product of lignin degradation. This technology uses a sealed autoclave with nitrogen displacing the air inside. The reaction is carried out at a temperature of 200-240°C and a pressure of 4-7 MPa for 3-7 hours, ultimately producing a lignin-derived liquid fuel. Although this technology can efficiently depolymerize lignin, the selectivity of alcohol products is low, and a large number of unsaturated small molecule products such as ketones and phenols are present in the products. At the same time, it uses a mixture of NaOH solution and low-carbon alcohols as a composite reaction solvent. On the one hand, the alkaline sodium hydroxide solution will cause certain corrosion to the reaction equipment (reactor), shortening the service life of the equipment. In addition, the treatment of the reaction liquid is complicated and tedious, and the discharge of waste liquid is likely to cause certain pollution to the environment, which also increases the cost of the process and the length of the preparation cycle. Summary of the Invention

[0007] The present invention aims to provide a one-step catalytic lignin selective hydrogenolysis method for preparing liquid oxygenated fuels, which is simple to prepare, has a low content of unsaturated small molecule product by-products, is convenient for post-processing, and does not require additional reduction. The method has a lignin conversion rate of 88.6-99.0%, a total yield of volatile products of 23.0-46.0%, a yield of alcohol liquid fuel products of 9.33-31.9%, and a selectivity of 32.8-71.0%.

[0008] The purpose of the present invention is achieved through the following technical solutions:

[0009] A one-step method for preparing liquid oxygenated fuel by catalytic selective hydrogenolysis of lignin comprises: adding a modified molecular sieve-supported hydrated ruthenium catalyst and an alcohol solvent to organically dissolved lignin, and reacting the catalyst at 210-290°C for 2-5 hours under an H2 pressure of 1-4 MPa to obtain an alcohol-based liquid oxygenated fuel; the modified molecular sieve-supported hydrated ruthenium catalyst is expressed as HRO@CaTS-x and comprises a carrier CaTS-x and an active component hydrated ruthenium HRO, wherein HRO is a ruthenium complex composed of Ru(OH)3, RuO2, and bonded water molecules; x represents the molar ratio of Ca to Ti in the carrier, which is 2-16.

[0010] In order to further achieve the purpose of the present invention, preferably, the preparation method of the hydrated ruthenium-based catalyst is: fully dissolving hydrated ruthenium trichloride (RuCl3·xH2O) in deionized water, adding CaTS-x and stirring, adjusting the pH to 9-10, filtering after 3-5 hours, washing the filter cake and drying it to obtain a modified molecular sieve-supported hydrated ruthenium catalyst.

[0011] Preferably, the CaTS-x is prepared by the following method: adding hydrochloric acid to deionized water to adjust the pH to 1-2, adding cetyltrimethylammonium bromide and calcium nitrate tetrahydrate, and adding tetraethyl silicate and tetrabutyl titanate dissolved in isopropyl alcohol after sufficient dissolution, stirring and fully co-hydrolyzing, adding tetrapropylammonium hydroxide to adjust the pH to 5-6, stirring until sufficient gel is formed, standing and then hydrothermally crystallizing at 170-180° C., filtering the crystallized liquid, washing and drying the filter cake, and then calcining in air to obtain CaTS-x;

[0012] The pH value is adjusted to 9-10 by adding ammonia water;

[0013] The filter cake is washed and then dried by washing the obtained filter cake with deionized water for 2 to 3 times and then drying it in an oven at 100 to 120°C.

[0014] Preferably, the mass ratio of cetyltrimethylammonium bromide, tetrapropylammonium hydroxide, tetraethyl silicate, calcium nitrate tetrahydrate and tetrabutyl titanate is 4:7:25:11:1 to 4:7:40:1:1.

[0015] Preferably, the stirring time until sufficient gelation occurs is 0.5 to 1 hour; the stirring time for sufficient co-hydrolysis after stirring is 20 to 24 hours; the standing time is 6 to 12 hours; the hydrothermal crystallization is carried out in a hydrothermal kettle; and the hydrothermal crystallization time is 2 to 3 days.

[0016] The calcination is carried out in a muffle furnace at a temperature of 500-600° C. for 3-5 hours.

[0017] The drying in the washing and drying is carried out in an oven at a drying temperature of 80 to 100° C. and a drying time of 10 to 12 hours.

[0018] Preferably, the mass ratio of lignin to hydrated ruthenium-based catalyst is 1:0.6-1:1.4, and the mass ratio of lignin to alcohol solvent is 1:10-1:20; and the HRO loading accounts for 3-7 wt.% of the total mass of the catalyst.

[0019] Preferably, the alcohol solvent is any one of methanol, ethanol and isopropanol.

[0020] Preferably, the organosoluble lignin is obtained by the following method: adding lignin and an extract into a reactor, reacting at 100-120° C. for 2-6 hours, and then filtering and separating; adding deionized water to the filtrate, filtering to obtain a solid, and drying to obtain the organosoluble lignin; the extract is composed of adding 3000-4000 mL of anhydrous ethanol and 800-1000 mL of deionized water to every 20-25 g of concentrated sulfuric acid, and adding 120-150 mL of the extract to every 10.0 g of lignin raw material.

[0021] Preferably, the lignin is derived from any one of bagasse, poplar, bamboo, straw, and corn cob.

[0022] Preferably, the liquid oxygen-containing fuel is one or more of cyclohexanol, 4-methylcyclohexanol, 4-ethylcyclohexanol and 4-propylcyclohexanol.

[0023] In the above technical measures of the present invention, the stirring speed involved in stirring until sufficient gelation, sufficient co-hydrolysis after stirring, adding CaTS-x and stirring is 300-400 r / min.

[0024] Compared with other lignin catalytic depolymerization technologies, the present invention has the following characteristics:

[0025] (1) The present invention addresses the current problems of low lignin depolymerization conversion rate and low yield and selectivity of alcohol-based liquid oxygen-containing products. By modifying conventional molecular sieves, a multi-level pore molecular sieve material with rich acidity and alkalinity and containing a large number of micropores and mesopores is prepared, which can catalyze the selective hydrogenolysis of lignin to obtain highly selective alcohol-based liquid oxygen-containing fuel products.

[0026] (2) The modified molecular sieve-supported hydrated ruthenium catalyst used in the present invention has excellent catalytic activity. Furthermore, its preparation process is simple, energy-saving, does not require additional reduction, and has minimal environmental pollution. The reaction conditions for lignin depolymerization are mild. A high yield of saturated alcohols can be obtained at a reaction pressure of 1 to 4 MPa and a reaction temperature of 210 to 290°C, achieving efficient and selective depolymerization of lignin under mild conditions.

[0027] (3) The catalyst used in the present invention can efficiently catalyze the hydrogenolysis of lignin while exhibiting high selectivity for saturated alcohol products. Lignin conversion can reach 88.6-99.0%, the total yield of volatile products can reach 23.0-46.0%, and the yield of alcohol liquid fuel products can reach 9.33-31.9%, with selectivity reaching 32.8-71.0%.

[0028] (4) The high selectivity of the catalyst of the present invention for high value-added chemicals not only helps to reduce the occurrence of side reactions, but also reduces the difficulty of separating the target product. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 This is the XRD pattern of CaTS-4 in Example 1 of the present invention.

[0030] Figure 2 The N2 physical adsorption-desorption isotherm and pore size distribution diagram of CaTS-x in Example 1 of the present invention.

[0031] Figure 3 This is the SEM image of CaTS-4 in Example 1 of the present invention.

[0032] Figure 4 This is the TEM image of CaTS-4 in Example 1 of the present invention.

[0033] Figure 5 This is the XRD pattern of HRO5@CaTS-x in Example 1 of the present invention.

[0034] Figure 6 The physical adsorption-desorption isotherm and pore size distribution diagram of HRO5@CaTS-4 in Example 1 of the present invention.

[0035] Figure 7 This is the SEM image of HRO5@CaTS-4 in Example 1 of the present invention.

[0036] Figure 8 This is the TEM image of HRO5@CaTS-4 in Example 1 of the present invention.

[0037] Figure 9 This is the H2-TPR spectrum of HRO5@CaTS-4 in Example 1 of the present invention.

[0038] Figure 10 This is the CO2-TPD diagram of HRO5@CaTS-4 in Example 1 of the present invention.

[0039] Figure 11 This is the NH3-TPD diagram of HRO5@CaTS-4 in Example 1 of the present invention.

[0040] Figure 12 This is the GC-MS-FID spectrum of the product obtained by HRO5@CaTS-4 catalyzing organic lignin dissolution in Example 9 of the present invention. DETAILED DESCRIPTION

[0041] For a better understanding of the present invention, the present invention is further described below with reference to the accompanying drawings and specific embodiments, but the embodiments of the present invention are not limited thereto. The embodiments described are part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0042] Liquid oxygenated fuels usually include: These substances have stable chemical properties and are widely used as alcoholic organic compounds in the fields of food, health products, cosmetics, etc. They can be used as organic reagents and can also be used to produce other chemicals, making them important chemical raw materials. In the pharmaceutical field, these saturated alcohol products are often used as pharmaceutical intermediates for organic synthesis. In addition, they can also serve as intermediates for emerging cycloalkane biofuels and are attractive fuel admixtures in jet and naval fuels. The liquid oxygenated fuel products of the present invention are one or more of cyclohexanol, 4-methylcyclohexanol, 4-ethylcyclohexanol, and 4-propylcyclohexanol.

[0043] The existing technology for preparing liquid oxygen-containing fuels using lignin has the following problems: low selectivity of alcohol products, the presence of a large number of unsaturated small molecular products such as ketones and phenols in the products, complex and tedious reaction liquid treatment, and waste liquid discharge that can easily cause certain pollution to the environment, increasing the cost of the process and the length of the preparation cycle. The main feature of the method for preparing liquid oxygen-containing fuels by one-step catalytic lignin selective hydrogenolysis of the present invention is the use of a hydrated ruthenium catalyst supported by a modified molecular sieve, which is expressed as HRO5@CaTS-x and consists of a carrier CaTS-x active component hydrated ruthenium. HRO is a ruthenium complex composed of Ru(OH)3, RuO2 and bonded water molecules, wherein the loading amount of hydrated ruthenium preferably accounts for 3-7wt.% of the total mass of the total catalyst, and x represents the molar ratio of Ca to Ti in the carrier CaTS-x, which is 2-16. The preparation method for the hydrated ruthenium-based catalyst is relatively simple: hydrated ruthenium trichloride (RuCl3·xH2O) is fully dissolved in deionized water, CaTS-x is added and stirred, and the pH is adjusted to 9-10. After 3-5 hours, the mixture is filtered, the filter cake is washed, and then dried. CaTS-x is prepared by the following method: hydrochloric acid is added to deionized water to adjust the pH to 1-2, cetyltrimethylammonium bromide and calcium nitrate tetrahydrate are added, and after fully dissolving, tetraethyl silicate and tetrabutyl titanate dissolved in isopropyl alcohol are added. After stirring, the mixture is fully co-hydrolyzed, and tetrapropylammonium hydroxide is added to adjust the pH to 5-6. The mixture is stirred until a gel is formed, and the mixture is allowed to stand for hydrothermal crystallization at 170-180°C. The crystallized solution is filtered, the filter cake is washed, dried, and then calcined in air to obtain CaTS-x. The mass ratio of hexadecyltrimethylammonium bromide, tetrapropylammonium hydroxide, tetraethyl silicate, calcium nitrate tetrahydrate, and tetrabutyl titanate is preferably 4:7:25:11:1 to 4:7:40:1:1. The tetrapropylammonium hydroxide serves not only as a pH regulator but also as a microporous template required for molecular sieve preparation. The gelling time, standing time, hydrothermal crystallization, calcination, pH adjustment, washing, and drying can all be determined based on existing technologies in accordance with the present invention. The stirring time to achieve complete gelling is preferably 0.5 to 1 hour; the stirring time for complete co-hydrolysis after stirring is preferably 20 to 24 hours; the standing time is preferably 6 to 12 hours; the hydrothermal crystallization is carried out in a hydrothermal kettle; the hydrothermal crystallization time is preferably 2 to 3 days; the calcination is preferably carried out in a muffle furnace at a temperature of 500 to 600°C for 3 to 5 hours; and the drying process during washing and drying is preferably carried out in an oven at a temperature of 80 to 100°C for 10 to 12 hours. In addition to the simplicity of the above-mentioned preparation method, the modified molecular sieve-loaded hydrated ruthenium catalyst of the present invention has abundant acidic and alkaline sites and a multi-level pore structure. The synergy between the two can enhance the ability to break the connecting bonds between the basic structural units of lignin. At the same time, the suitable pore structure is beneficial to mass transfer and target product selection during the catalytic hydrogenolysis process, thereby facilitating the selective hydrogenolysis of lignin to obtain a high-yield alcohol-based liquid oxygen-containing fuel.

[0044] To this end, the present invention provides a one-step catalytic selective hydrogenolysis method for preparing liquid oxygenated fuels using organosoluble lignin as the raw material. After adding a hydrated ruthenium-based catalyst and an alcohol solvent to the raw material, the reaction is carried out at a hydrogen pressure of 1 to 4 MPa and 210 to 290°C for 2 to 6 hours to depolymerize the lignin and obtain the liquid oxygenated fuel. In the technical measures of the present invention, the alcohol solvent medium, due to its inherent hydroxyl groups, is an excellent hydrogen donor and can also promote hydrogen exchange between the solvent and hydrogen, which is beneficial for the cleavage of CO bonds in the lignin. Using the present method, the lignin conversion rate can reach 88.6 to 99.0%, the total yield of volatile products can reach 23.0 to 46.0%, the yield of alcohol liquid fuel products can reach 9.33 to 31.9%, and the selectivity can reach 32.8 to 71.0%.

[0045] The lignin extraction method of the present invention is essentially a method already disclosed in the prior art. Specifically, a lignin raw material and an extracting solution are added to a reactor, reacted at 100-120°C for 2-6 hours, and then filtered and separated. The resulting filtrate is added with deionized water, filtered to obtain a solid, and then dried to obtain an organosoluble lignin. The extracting solution comprises a mixture of concentrated sulfuric acid, anhydrous ethanol, and deionized water. The mass concentration of the concentrated sulfuric acid is 95-98%, and 3200-4000 mL of anhydrous ethanol and 800-1000 mL of deionized water are added to every 24 g of concentrated sulfuric acid. 120-150 mL of the extracting solution is added to every 10.0 g of the lignin raw material. The lignin can be derived from any of bagasse, corn stalks, poplar, and bamboo. The mass ratio of lignin to hydrated ruthenium-based catalyst is preferably 1:0.2 to 1:1.2. The mass ratio of lignin to alcoholic solvent is preferably 1:10 to 1:20. The alcoholic solvent is preferably any of methanol, ethanol, and isopropanol.

[0046] Example 1: Preparation of HRO5@CaTS-4 catalyst

[0047] The CaTS-4 catalyst is achieved through a two-step process:

[0048] (1) The preparation method of the carrier CaTS-4 is as follows: weigh 50 ml of deionized water in a beaker, add an appropriate amount of hydrochloric acid to adjust the pH to 1, add 2.915 g of hexadecyltrimethylammonium bromide (CTAB) and 2 g of calcium nitrate tetrahydrate respectively, and add 17.7 ml of tetraethyl silicate after they are fully dissolved. At the same time, dissolve 0.68 ml of tetrabutyl titanate in 6.5 ml of isopropanol, slowly drop them into the above solution and stir for 20 hours to fully hydrolyze them. Then, slowly add 20 ml of tetrapropylammonium hydroxide to the solution to adjust the pH to 5, stir for half an hour to fully gelate it, and after standing for 12 hours, place the gel in a hydrothermal autoclave and hydrothermally crystallize it at 180°C for two days. Filter the crystal liquid to obtain a white solid, wash and dry it, and calcine it in air. The obtained gray-yellow solid is CaTS-4.

[0049] The prepared CaTS-4 was characterized by X-ray diffraction to explore its crystal structure. Figure 1 As shown in Figure 3, the prepared catalyst has a typical MFI topological structure, with obvious diffraction peaks observed at 8.0°, 8.6°, 23.1°, 24.0°, and 24.4°, which are attributed to the (101), (200), (002), (332), (051), and (303) crystal planes of MFI, respectively. In addition, as the Ca / Ti molar ratio decreases, the characteristic diffraction peaks of the catalyst gradually become stronger, indicating that a smaller Ca / Ti ratio is conducive to the crystallization of the molecular sieve.

[0050] The prepared CaTS-4 was characterized by N2 physical adsorption and desorption to explore its pore structure. Figure 2 As shown. Figure 2 It can be seen that the adsorption isotherms of CaTS-x prepared with different Ca / Ti molar ratios are all typical type IV isotherms, and a clear H4 hysteresis loop can be observed, indicating the presence of a mesoporous structure in the support. Combined with the pore size distribution, it can be seen that when the Ca / Ti molar ratio is 16, the catalyst mainly contains mesopores of 20-50 nm. When the Ca / Ti molar ratios are 2, 4, and 8, the mesopores and micropores on the catalyst increase. Among them, CaTS-4 has micropores of 0.6-0.7 nm and 1.2-1.6 nm, small mesopores of 2.1-2.9 nm, and some large mesopores and macropores, showing the richest pore structure. This multi-level pore structure is beneficial for mass transfer and target product selection during catalytic hydrogenolysis.

[0051] The surface morphology of the prepared CaTS-4 was investigated by SEM and TEM. Figure 3 and Figure 4 shown. Figure 3 Shown are SEM images of CaTS-4 taken at different magnifications. It can be clearly observed that the carrier is a three-dimensional interlayer structure formed by the accumulation of nanosheets. On the one hand, this structure helps to anchor the metal active center and stabilize the catalytic activity of the catalyst. On the other hand, it is conducive to exposing more active sites, which is conducive to reducing mass transfer resistance and making the catalyst exhibit higher catalytic activity. Figure 4 Shown are TEM images, high-resolution TEM images and TEM selected-area electron diffraction images of CaTS-4 taken at different magnifications. The TEM images also show that CaTS-4 has a three-dimensional layer network structure. The TEM selected-area electron diffraction image is ring-shaped, indicating that the catalyst is polycrystalline. Further analysis of the lattice fringes on the catalyst shows that the lattice spacings observed in the high-resolution TEM image are 1.03 nm and 0.37 nm, respectively, corresponding to the (200) crystal plane and (033) crystal plane of the MFI molecular sieve.

[0052] (2) Preparation of HRO5@CaTS-4 catalyst: Weigh 0.0324 g of RuCl3·xH2O solid and dissolve it in 150 ml of deionized water. Add the solution to a beaker containing 0.3 g of CaTS-4, add an appropriate amount of ammonia water to adjust the pH of the solution to 10, stir vigorously for 4 h, and filter. Wash the filter cake three times with deionized water and then dry it in an oven at 80°C. After drying, grind the sample into powder. The resulting solid is HRO5@CaTS-4.

[0053] The prepared HRO5@CaTS-4 catalyst was characterized by X-ray diffraction to explore its phase structure. Figure 5 The results show that the catalyst loaded with hydrated ruthenium has obvious diffraction peaks at 8.0°, 8.6°, 23.1°, 24.0°, and 24.4°, indicating that the carrier HRO5@CaTS-4 still maintains its original phase structure, while HRO has no relevant diffraction peaks due to its amorphous nature.

[0054] The prepared HRO5@CaTS-4 catalyst was characterized by N2 physical adsorption and desorption to explore its pore structure. Figure 6 shown. Figure 6 The N2 physical adsorption-desorption isotherm and pore size distribution of HRO5@CaTS-4 are shown. The N2 physical adsorption-desorption isotherm of the catalyst is also a typical type IV isotherm, with a distinct H4-type hysteresis loop, indicating the presence of a mesoporous structure. Combined with the pore size distribution, the pore size distribution of the catalyst remains unchanged after HRO loading, with micropores ranging from 0.6 to 0.7 nm and 1.2 to 1.6 nm, small mesopores ranging from 2.1 to 2.9 nm, and some large mesopores and macropores.

[0055] The prepared HRO5@CaTS-4 catalyst was characterized by SEM to explore its surface morphology. Figure 7 shown. Figure 7 SEM images and EDS mapping images of the HRO5@CaTS-4 catalyst, taken at different magnifications, show that after CaTS-4 is loaded with HRO, the HRO nanoparticles are dispersed abundantly within the interstices of the nanosheets, resulting in a more folded nanosheet and a denser spherical structure. The EDS mapping image demonstrates the uniform distribution of all elements in the catalyst.

[0056] The prepared HRO5@CaTS-4 catalyst was characterized by TEM to explore its microstructure. Figure 8 shown. Figure 8The following are the TEM images, high-resolution TEM images and EDS mapping images of the HRO5@CaTS-4 catalyst after fresh and catalytic lignin hydrogenolysis. Compared with the pure carrier CaTS-4, the TEM image shows that the catalyst with a three-dimensional network interlayer structure after loading has many nanoparticles, indicating the successful loading of HRO. The high-resolution TEM image shows that the lattice spacing of 0.209nm and 0.227nm are observed on the HRO5@CaTS-4 catalyst after catalytic lignin hydrogenolysis, which correspond to the (101) crystal plane of Ru (PDF#88-1734) species and the (200) crystal plane of RuO2 (PDF#88-0323) species, respectively. This indicates that after the catalytic lignin hydrogenolysis process, part of HRO is in situ reduced to zero-valent Ru species, and the other part is converted into RuO2. At the same time, its EDS mapping results show that the Ru element is well dispersed on the catalyst, which is conducive to improving the catalytic lignin hydrogenolysis activity.

[0057] The prepared catalyst was characterized by H2-TPR to explore its redox performance. Figure 9 HRO5@CaTS-4 has a peak at 159℃ and 266℃, which are respectively attributed to Ru in HRO. 3+ With Ru 4+ Restoration.

[0058] The prepared HRO5@CaTS-4 catalyst was characterized by NH3-TPD to explore its acidity. Figure 10 As shown in Figure 3 , five NH3 desorption peaks were obtained from the catalyst through peak fitting. The NH3-TPD can be divided into three temperature ranges: the desorption peak below 150°C corresponds to weak acid sites, the desorption peak between 150-450°C corresponds to medium-strong acid sites, and the desorption peak above 450°C corresponds to strong acid sites. The results show that the acid distribution of the catalyst is primarily dominated by weak acid sites, with some medium-strong acid sites and strong acid sites also present.

[0059] The prepared catalyst was characterized by CO2-TPD to explore its basicity. Figure 11 As shown, the catalyst also exhibited five desorption peaks through peak fitting. CO2-TPD can be divided into three temperature ranges: the desorption peak below 270°C corresponds to weak base sites, the desorption peak between 200-500°C corresponds to medium-strong base sites, and the desorption peak above 500°C corresponds to strong base sites. The catalyst is primarily characterized by medium-strong base sites, with both strong and weak base sites. Combined with NH3-TPD characterization results, the HRO5@CaTS-4 catalyst has a rich acidity and alkalinity profile, which is beneficial for the efficient and selective depolymerization of lignin.

[0060] Example 2: Preparation of HRO3@CaTS-4 catalyst

[0061] The preparation of HRO3@CaTS-4 catalyst is achieved by a two-step process:

[0062] (1) The preparation method of the carrier CaTS-4 is as follows: weigh 50 ml of deionized water in a beaker, add an appropriate amount of hydrochloric acid to adjust the pH to 1, add 2.915 g of hexadecyltrimethylammonium bromide (CTAB) and 2 g of calcium nitrate tetrahydrate respectively, and add 17.7 ml of tetraethyl silicate after they are fully dissolved. At the same time, dissolve 0.68 ml of tetrabutyl titanate in 6.5 ml of isopropanol, slowly drop them into the above solution and stir for 20 hours to fully hydrolyze them. Then, slowly add 20 ml of tetrapropylammonium hydroxide to the solution to adjust the pH to 5, stir for half an hour to fully gelate it, and after standing for 12 hours, place the gel in a hydrothermal autoclave and hydrothermally crystallize it at 180°C for two days. Filter the crystal liquid to obtain a white solid, wash and dry it, and calcine it in air. The obtained gray-yellow solid is CaTS-4.

[0063] (2) Preparation of catalyst 6: Weigh 0.0193 g of RuCl3·xH2O solid and dissolve it in 150 ml of deionized water. Add the solution to a beaker containing 0.3 g of CaTS-4. Add an appropriate amount of ammonia water to adjust the pH of the solution to 10. After vigorous stirring for 4 h, filter the solution. Wash the filter cake three times with deionized water and then dry it in an oven at 80°C. After drying, grind the sample into powder. The resulting solid is HRO3@CaTS-4.

[0064] Example 3: Preparation of HRO3@CaTS-4 catalyst

[0065] The preparation of HRO3@CaTS-4 catalyst is achieved by a two-step process:

[0066] (1) The preparation method of the carrier CaTS-4 is as follows: weigh 50 ml of deionized water in a beaker, add an appropriate amount of hydrochloric acid to adjust the pH to 1, add 2.915 g of hexadecyltrimethylammonium bromide (CTAB) and 2 g of calcium nitrate tetrahydrate respectively, and add 17.7 ml of tetraethyl silicate after they are fully dissolved. At the same time, dissolve 0.68 ml of tetrabutyl titanate in 6.5 ml of isopropanol, slowly drop them into the above solution and stir for 20 hours to fully hydrolyze them. Then, slowly add 20 ml of tetrapropylammonium hydroxide to the solution to adjust the pH to 5, stir for half an hour to fully gelate it, and after standing for 12 hours, place the gel in a hydrothermal autoclave and hydrothermally crystallize it at 180°C for two days. Filter the crystal liquid to obtain a white solid, wash and dry it, and calcine it in air. The obtained gray-yellow solid is CaTS-4.

[0067] (2) Preparation of HRO7@CaTS-4 catalyst: Weigh 0.0482 g of RuCl3·xH2O solid and dissolve it in 150 ml of deionized water. Add the solution to a beaker containing 0.3 g of CaTS-4, add an appropriate amount of ammonia water to adjust the pH of the solution to 10, stir vigorously for 4 h, and filter. Wash the filter cake three times with deionized water and then dry it in an oven at 80°C. After drying, grind the sample into powder. The resulting solid is HRO7@CaTS-4.

[0068] Example 4: Preparation of HRO5@CaTS-16 catalyst

[0069] The preparation of HRO5@CaTS-16 catalyst is achieved by a two-step process:

[0070] (1) Preparation of CaTS-16 carrier: Weigh 50 ml of deionized water into a beaker, add appropriate amount of hydrochloric acid to adjust the pH to 1, add 2.915 g of hexadecyltrimethylammonium bromide (CTAB) and 8 g of calcium nitrate tetrahydrate respectively, and add 17.7 ml of tetraethyl silicate after they are fully dissolved. At the same time, dissolve 0.68 ml of tetrabutyl titanate in 6.5 ml of isopropanol, slowly drip into the above solution and stir for 20 hours to allow it to be fully hydrolyzed. Then slowly add 20 ml of tetrapropylammonium hydroxide to the solution to adjust the pH to 5, stir for half an hour to allow it to fully gel. After standing for 12 hours, place the gel in a hydrothermal autoclave and hydrothermally crystallize at 180°C for two days. Filter the crystal liquid to obtain a white solid, wash and dry it, and calcine it in air. The obtained gray-yellow solid is CaTS-16.

[0071] (2) Preparation of HRO5@CaTS-16 catalyst: 0.0324 g of hydrated ruthenium trichloride (RuCl3·xH2O) was fully dissolved in 150 ml of deionized water, 0.3 g of CaTS-16 was added and stirred, and an appropriate amount of ammonia was added to adjust the pH to 10. After 4 h, the mixture was filtered and washed three times with deionized water. The filter cake was placed in an oven at 80 °C and dried for 12 h. After drying, the sample was ground into powder, and the resulting solid was HRO5@CaTS-16.

[0072] Example 5: Preparation of HRO5@CaTS-8 catalyst

[0073] The preparation of HRO5@CaTS-8 catalyst was achieved by a two-step process:

[0074] (1) Preparation of CaTS-8 carrier: Weigh 50 ml of deionized water into a beaker, add appropriate amount of hydrochloric acid to adjust the pH to 1, add 2.915 g of hexadecyltrimethylammonium bromide (CTAB) and 4 g of calcium nitrate tetrahydrate respectively, and add 17.7 ml of tetraethyl silicate after they are fully dissolved. At the same time, dissolve 0.68 ml of tetrabutyl titanate in 6.5 ml of isopropanol, slowly drip into the above solution and stir for 20 hours to allow it to be fully hydrolyzed. Then slowly add 20 ml of tetrapropylammonium hydroxide to the solution to adjust the pH to 5, stir for half an hour to allow it to fully gel. After standing for 12 hours, place the gel in a hydrothermal autoclave and hydrothermally crystallize at 180°C for two days. Filter the crystal liquid to obtain a white solid, wash and dry it, and calcine it in air. The obtained gray-yellow solid is CaTS-8.

[0075] (2) Preparation of HRO5@CaTS-8 catalyst: 0.0324 g of hydrated ruthenium trichloride (RuCl3·xH2O) was fully dissolved in 150 ml of deionized water, 0.3 g of CaTS-8 was added and stirred, and an appropriate amount of ammonia was added to adjust the pH to 10. After 4 h, the mixture was filtered and washed three times with deionized water. The filter cake was placed in an oven at 80 °C and dried for 12 h. After drying, the sample was ground into powder. The resulting solid was HRO5@CaTS-8.

[0076] Example 6: Preparation of HRO5@CaTS-2 catalyst

[0077] The preparation of HRO5@CaTS-2 catalyst was achieved by a two-step process:

[0078] (1) Preparation of CaTS-2 carrier: Weigh 50 ml of deionized water in a beaker, add appropriate amount of hydrochloric acid to adjust the pH to 1, add 2.915 g of hexadecyltrimethylammonium bromide (CTAB) and 4 g of calcium nitrate tetrahydrate respectively, and add 17.7 ml of tetraethyl silicate after they are fully dissolved. At the same time, dissolve 0.68 ml of tetrabutyl titanate in 6.5 ml of isopropanol, slowly drip into the above solution and stir for 20 hours to allow it to be fully hydrolyzed. Then slowly add 20 ml of tetrapropylammonium hydroxide to the solution to adjust the pH to 5, stir for half an hour to allow it to fully gel. After standing for 12 hours, place the gel in a hydrothermal autoclave and hydrothermally crystallize at 180°C for two days. Filter the crystal liquid to obtain a white solid, wash and dry it, and calcine it in air. The obtained gray-yellow solid is CaTS-2.

[0079] (2) Preparation of HRO5@CaTS-2 catalyst: 0.0324 g of hydrated ruthenium trichloride (RuCl3·xH2O) was fully dissolved in 150 ml of deionized water, 0.3 g of CaTS-2 was added and stirred, and an appropriate amount of ammonia was added to adjust the pH to 10. After 4 h, the mixture was filtered and washed three times with deionized water. The filter cake was placed in an oven at 80 °C and dried for 12 h. After drying, the sample was ground into powder, and the resulting solid was HRO5@CaTS-2.

[0080] Example 7: HRO5@CaTS-4 catalyzes lignin depolymerization

[0081] (1) Lignin extraction: Weigh 10.0 g of sugarcane bagasse raw material and 120 mL of extracting solution into a 250 mL hydrothermal kettle and place in an oven at 110°C for 4 h. After cooling to room temperature, filter and wash with ethanol. Collect the filtrate and washing solution, and add 500 mL of deionized water to precipitate lignin. After filtering through a 0.22 μm filter membrane, place in a fume hood to air dry, and grind into powder to obtain organosoluble bagasse lignin. The extracting solution consists of 24 g of 98% concentrated sulfuric acid, 3200 mL of anhydrous ethanol, and 800 mL of deionized water.

[0082] (2) Catalytic depolymerization of lignin: 100 mg of the organic-soluble bagasse lignin extracted in step (1), 120 mg of HRO5@CaTS-4 catalyst, and 20 mL of isopropanol were weighed in a 50 mL reactor. The reactor was sealed, the air in the reactor was replaced three times with high-purity hydrogen, and 2.0 MPa of hydrogen was filled in. The reaction was carried out at 270 ° C for 4 h. After the reaction was completed and cooled to room temperature, the reaction solution was taken out and added with internal standard dimethyl phthalate. 1 mL of the reaction solution was analyzed by GC-MS-FID. The reaction solution was filtered to obtain a filtrate, and deionized water was added to 200 mL. The solution was allowed to stand for about 24 h to precipitate the unreacted lignin. After filtration and drying, the regenerated lignin was obtained.

[0083] The chromatographic column was 30 m × 0.25 mm × 0.25 μm and the flow rate was 2 mL min-1. -1 , split ratio 4:1. Heating program: 50℃ for 1min, then 10℃ for -1 The heating rate was raised to 280°C and maintained for 15 min) to conduct qualitative analysis and quantitative calculation of the product. The GC-FID results of the product are as follows Figure 12 and as shown in Table 1.

[0084] The calculation results show that under the action of HRO5@CaTS-4 catalyst, the conversion rate of lignin reached 97.6%, the total yield of volatile products was 46.0%, and the yield and selectivity of saturated alcohol products mainly composed of 4-ethylcyclohexanol were 31.9% and 69.5%, respectively.

[0085] Table 1 Volatile product identity and yield

[0086]

[0087]

[0088] Example 8: HRO3@CaTS-4 catalyzed lignin depolymerization

[0089] (1) Lignin extraction: Weigh 10.0 g of sugarcane bagasse raw material and 120 mL of extracting solution into a 250 mL hydrothermal kettle and place in an oven at 110°C for 4 h. After cooling to room temperature, filter and wash with ethanol. Collect the filtrate and washing solution, and add 500 mL of deionized water to precipitate lignin. After filtering through a 0.22 μm filter membrane, place in a fume hood to air dry, and grind into powder to obtain organosoluble bagasse lignin. The extracting solution consists of 24 g of 98% concentrated sulfuric acid, 3200 mL of anhydrous ethanol, and 800 mL of deionized water.

[0090] (2) Catalytic depolymerization of lignin: 100 mg of the organic-soluble bagasse lignin extracted in step (1), 120 mg of HRO3@CaTS-4 catalyst, and 20 mL of isopropanol were weighed in a 50 mL reactor. The reactor was sealed, the air in the reactor was replaced three times with high-purity hydrogen, and 2.0 MPa of hydrogen was filled in. The reaction was carried out at 270°C for 4 h. After the reaction was completed and cooled to room temperature, the reaction solution was taken out and added with internal standard dimethyl phthalate. 1 mL of the reaction solution was analyzed by GC-MS-FID. The reaction solution was filtered to obtain a filtrate, and deionized water was added to 200 mL. The solution was allowed to stand for about 24 h to precipitate the unreacted lignin. After filtration and drying, the regenerated lignin was obtained.

[0091] The calculation results show that the conversion rate of lignin is 94.4%, the total yield of volatile products is 17.8%, and the yield and selectivity of saturated alcohol products are 9.9% and 52.7%, respectively.

[0092] Example 9: HRO7@CaTS-4 catalyzes lignin depolymerization

[0093] (1) Lignin extraction: Weigh 10.0 g of sugarcane bagasse raw material and 120 mL of extracting solution into a 250 mL hydrothermal kettle and place in an oven at 110°C for 4 h. After cooling to room temperature, filter and wash with ethanol. Collect the filtrate and washing solution, and add 500 mL of deionized water to precipitate lignin. After filtering through a 0.22 μm filter membrane, place in a fume hood to air dry, and grind into powder to obtain organosoluble bagasse lignin. The extracting solution consists of 24 g of 98% concentrated sulfuric acid, 3200 mL of anhydrous ethanol, and 800 mL of deionized water.

[0094] (2) Catalytic depolymerization of lignin: 100 mg of the organic-soluble bagasse lignin extracted in step (1), 120 mg of HRO7@CaTS-4 catalyst, and 20 mL of isopropanol were weighed in a 50 mL reactor. The reactor was sealed, the air in the reactor was replaced three times with high-purity hydrogen, and 2.0 MPa of hydrogen was filled in. The reaction was carried out at 270 ° C for 4 h. After the reaction was completed and cooled to room temperature, the reaction solution was taken out and added with internal standard dimethyl phthalate. 1 mL of the reaction solution was analyzed by GC-MS-FID. The reaction solution was filtered to obtain a filtrate, and deionized water was added to 200 mL. The solution was allowed to stand for about 24 h to precipitate the unreacted lignin. After filtration and drying, the regenerated lignin was obtained.

[0095] The calculated results showed that the conversion rate of lignin was 95.0%, the total yield of volatile products was 27.1%, and the yield and selectivity of saturated alcohol products were 17.2% and 64.2%, respectively.

[0096] Example 10: HRO5@CaTS-16 catalyzes lignin depolymerization

[0097] The difference between this embodiment and embodiment 5 is that:

[0098] 100 mg of organosoluble bagasse lignin, 100 mg of HRO5@CaTS-16 catalyst, and 20 mL of isopropanol were weighed sequentially into a 50 mL reactor. The reactor was sealed, the air in the reactor was replaced three times with high-purity hydrogen, and then filled with 2.0 MPa of hydrogen. The reaction was carried out at 270°C for 4 hours. After the reaction was completed and cooled to room temperature, the reaction solution was removed and added with dimethyl phthalate as an internal standard. 1 mL of the reaction solution was analyzed by GC-MS-FID.

[0099] The calculation results show that the conversion rate of lignin is 91.1%, the total yield of volatile products is 17.8%, and the yield and selectivity of saturated alcohol products are 11.9% and 66.8%, respectively.

[0100] Example 11: HRO5@CaTS-8 catalyzes lignin depolymerization

[0101] The difference between this embodiment and embodiment 5 is that:

[0102] 100 mg of organosoluble bagasse lignin, 100 mg of HRO5@CaTS-8 catalyst, and 20 mL of isopropanol were weighed sequentially into a 50 mL reactor. The reactor was sealed, the air in the reactor was replaced three times with high-purity hydrogen, and then filled with 2.0 MPa of hydrogen. The reaction was carried out at 270°C for 4 hours. After the reaction was completed and cooled to room temperature, the reaction solution was removed and added with dimethyl phthalate as an internal standard. 1 mL of the reaction solution was analyzed by GC-MS-FID.

[0103] The calculated results showed that the conversion rate of lignin was 94.0%, the total yield of volatile products was 27.5%, and the yield and selectivity of saturated alcohol products were 19.5% and 71.2%, respectively.

[0104] Example 12: HRO5@CaTS-2 catalyzes lignin depolymerization

[0105] The difference between this embodiment and embodiment 5 is that:

[0106] 100 mg of organosoluble bagasse lignin, 100 mg of HRO5@CaTS-8 catalyst, and 20 mL of isopropanol were weighed sequentially into a 50 mL reactor. The reactor was sealed, the air in the reactor was replaced three times with high-purity hydrogen, and then filled with 2.0 MPa of hydrogen. The reaction was carried out at 270°C for 4 hours. After the reaction was completed and cooled to room temperature, the reaction solution was removed and added with dimethyl phthalate as an internal standard. 1 mL of the reaction solution was analyzed by GC-MS-FID.

[0107] The calculation results show that the conversion rate of lignin is 94.0%, the total yield of volatile products is 27.8%, and the yield and selectivity of saturated alcohol products are 18.3% and 65.8%, respectively.

[0108] Example 13: HRO5@CaTS-4 catalyzes lignin depolymerization

[0109] The difference between this embodiment and embodiment 5 is that:

[0110] 100 mg of organosoluble bagasse lignin, 140 mg of HRO5@CaTS-4 catalyst, and 20 mL of isopropanol were weighed sequentially into a 50 mL reactor. The reactor was sealed, the air in the reactor was replaced three times with high-purity hydrogen, and then filled with 2.0 MPa of hydrogen. The reaction was carried out at 270°C for 4 hours. After the reaction was completed and cooled to room temperature, the reaction solution was removed and added with dimethyl phthalate as an internal standard. 1 mL of the reaction solution was analyzed by GC-MS-FID.

[0111] The calculation results show that the conversion rate of lignin is 98.7%, the total yield of volatile products is 41.1%, and the yield and selectivity of saturated alcohol products are 24.2% and 59.0%, respectively.

[0112] Example 14: HRO5@CaTS-4 catalyzes lignin depolymerization

[0113] The difference between this embodiment and embodiment 5 is that:

[0114] 100 mg of organosoluble bagasse lignin, 100 mg of HRO5@CaTS-4 catalyst, and 20 mL of isopropanol were weighed sequentially into a 50 mL reactor. The reactor was sealed, the air in the reactor was replaced three times with high-purity hydrogen, and then filled with 2.0 MPa of hydrogen. The reaction was carried out at 270°C for 4 hours. After the reaction was completed and cooled to room temperature, the reaction solution was removed and added with dimethyl phthalate as an internal standard. 1 mL of the reaction solution was analyzed by GC-MS-FID.

[0115] The calculation results show that the conversion rate of lignin is 97.5%, the total yield of volatile products is 35.5%, and the yield and selectivity of saturated alcohol products are 25.2% and 71.0%, respectively.

[0116] Example 15: HRO5@CaTS-4 catalyzes lignin depolymerization

[0117] The difference between this embodiment and embodiment 5 is that:

[0118] 100 mg of organosoluble bagasse lignin, 80 mg of HRO5@CaTS-4 catalyst, and 20 mL of isopropanol were weighed sequentially into a 50 mL reactor. The reactor was sealed, the air in the reactor was replaced three times with high-purity hydrogen, and then filled with 2.0 MPa of hydrogen. The reaction was carried out at 270°C for 4 hours. After the reaction was completed and cooled to room temperature, the reaction solution was removed and added with dimethyl phthalate as an internal standard. 1 mL of the reaction solution was analyzed by GC-MS-FID.

[0119] The calculation results show that the conversion rate of lignin is 93.0%, the total yield of volatile products is 28.2%, and the yield and selectivity of saturated alcohol products are 16.5% and 58.4%, respectively.

[0120] Example 16: HRO5@CaTS-4 catalyzes lignin depolymerization

[0121] The difference between this embodiment and embodiment 5 is that:

[0122] 100 mg of organosoluble bagasse lignin, 120 mg of HRO5@CaTS-4 catalyst, and 20 mL of isopropanol were weighed sequentially into a 50 mL reactor. The reactor was sealed, the air in the reactor was replaced three times with high-purity hydrogen, and then filled with 1.0 MPa of hydrogen. The reaction was carried out at 270°C for 4 hours. After the reaction was completed and cooled to room temperature, the reaction solution was removed and added with dimethyl phthalate as an internal standard. 1 mL of the reaction solution was analyzed by GC-MS-FID.

[0123] The calculation results show that the conversion rate of lignin is 95.2%, the total yield of volatile products is 37.8%, and the yield and selectivity of saturated alcohol products are 25.7% and 68.1%, respectively.

[0124] Example 17: HRO5@CaTS-4 catalyzes lignin depolymerization

[0125] The difference between this embodiment and embodiment 5 is that:

[0126] 100 mg of organosoluble bagasse lignin, 120 mg of HRO5@CaTS-4 catalyst, and 20 mL of isopropanol were weighed sequentially into a 50 mL reactor. The reactor was sealed, the air in the reactor was replaced three times with high-purity hydrogen, and then filled with 3.0 MPa of hydrogen. The reaction was carried out at 270°C for 4 hours. After the reaction was completed and cooled to room temperature, the reaction solution was removed and added with dimethyl phthalate as an internal standard. 1 mL of the reaction solution was analyzed by GC-MS-FID.

[0127] The calculation results show that the conversion rate of lignin is 95.7%, the total yield of volatile products is 40.8%, and the yield and selectivity of saturated alcohol products are 26.2% and 64.3%, respectively.

[0128] Example 18: HRO5@CaTS-4 catalyzes lignin depolymerization

[0129] The difference between this embodiment and embodiment 5 is that:

[0130] 100 mg of organosoluble bagasse lignin, 120 mg of HRO5@CaTS-4 catalyst, and 20 mL of isopropanol were weighed sequentially into a 50 mL reactor. The reactor was sealed, the air in the reactor was replaced three times with high-purity hydrogen, and then filled with 2.0 MPa of hydrogen. The reaction was carried out at 270°C for 2 h. After the reaction was completed and cooled to room temperature, the reaction solution was removed and added with dimethyl phthalate as an internal standard. 1 mL of the reaction solution was analyzed by GC-MS-FID.

[0131] The calculation results show that the conversion rate of lignin is 92.1%, the total yield of volatile products is 25.5%, and the yield and selectivity of saturated alcohol products are 17.1% and 67.3%, respectively.

[0132] Example 19: HRO5@CaTS-4 catalyzes lignin depolymerization

[0133] The difference between this embodiment and embodiment 5 is that:

[0134] 100 mg of organosoluble bagasse lignin, 120 mg of HRO5@CaTS-4 catalyst, and 20 mL of isopropanol were weighed sequentially into a 50 mL reactor. The reactor was sealed, the air in the reactor was replaced three times with high-purity hydrogen, and then filled with 2.0 MPa of hydrogen. The reaction was carried out at 270°C for 3 hours. After the reaction was completed and cooled to room temperature, the reaction solution was removed and added with dimethyl phthalate as an internal standard. 1 mL of the reaction solution was analyzed by GC-MS-FID.

[0135] The calculation results show that the conversion rate of lignin is 94.2%, the total yield of volatile products is 33.5%, and the yield and selectivity of saturated alcohol products are 22.8% and 68.1%, respectively.

[0136] Example 20: HRO5@CaTS-4 catalyzes lignin depolymerization

[0137] The difference between this embodiment and embodiment 5 is that:

[0138] 100 mg of organosoluble bagasse lignin, 120 mg of HRO5@CaTS-4 catalyst, and 20 mL of isopropanol were weighed sequentially into a 50 mL reactor. The reactor was sealed, the air in the reactor was replaced three times with high-purity hydrogen, and then filled with 2.0 MPa of hydrogen. The reaction was carried out at 270°C for 5 hours. After the reaction was completed and cooled to room temperature, the reaction solution was removed and added with dimethyl phthalate as an internal standard. 1 mL of the reaction solution was analyzed by GC-MS-FID.

[0139] The calculation results show that the conversion rate of lignin is 97.9%, the total yield of volatile products is 42.2%, and the yield and selectivity of saturated alcohol products are 27.9% and 66.0%, respectively.

[0140] Example 21: HRO5@CaTS-4 catalyzes lignin depolymerization

[0141] The difference between this embodiment and embodiment 5 is that:

[0142] (1) Lignin extraction: Weigh 10.0 g of bamboo raw material and 120 mL of extract solution, add them to a 250 mL hydrothermal kettle, and place in an oven at 110°C for 4 h. After cooling to room temperature, filter and wash with ethanol. Collect the filtrate and washing solution, and add 500 mL of deionized water to precipitate the lignin. After filtering through a 0.22 μm filter membrane, place in a fume hood to air dry, and grind into powder to obtain organic-soluble bamboo lignin. The extract solution consists of 24 g of 98% concentrated sulfuric acid, 3200 mL of anhydrous ethanol, and 800 mL of deionized water.

[0143] (2) Catalytic depolymerization of lignin: 100 mg of the organic-soluble bamboo lignin extracted in step (1), 120 mg of HRO5@CaTS-4 catalyst, and 20 mL of isopropanol were weighed in a 50 mL reactor. The reactor was sealed, the air in the reactor was replaced three times with high-purity hydrogen, and 2.0 MPa of hydrogen was filled in. The reaction was carried out at 270°C for 4 h. After the reaction was completed and cooled to room temperature, the reaction solution was taken out and added with internal standard dimethyl phthalate. 1 mL of the reaction solution was analyzed by GC-MS-FID. The reaction solution was filtered to obtain a filtrate, and deionized water was added to 200 mL. The filtrate was allowed to stand for about 24 h to precipitate the unreacted lignin. After filtration and drying, the regenerated lignin was obtained.

[0144] The calculation results show that the conversion rate of lignin is 99.0%, the total yield of volatile products is 41.2%, and the yield and selectivity of saturated alcohol products are 29.4% and 70.6%, respectively.

[0145] Example 22: HRO5@CaTS-4 catalyzes lignin depolymerization

[0146] The difference between this embodiment and embodiment 5 is that:

[0147] (1) Lignin extraction: Weigh 10.0 g of poplar wood raw material and 120 mL of extract solution, add them to a 250 mL hydrothermal kettle, and place in an oven at 110°C for 4 h. After cooling to room temperature, filter and wash with ethanol. Collect the filtrate and washing solution, and add 500 mL of deionized water to precipitate lignin. After filtering through a 0.22 μm filter membrane, place in a fume hood to air dry, and grind into powder to obtain organic-soluble poplar wood lignin. The extract solution consists of 24 g of 98% concentrated sulfuric acid, 3200 mL of anhydrous ethanol, and 800 mL of deionized water.

[0148] (2) Catalytic depolymerization of lignin: 100 mg of the organic-soluble poplar lignin extracted in step (1), 120 mg of HRO5@CaTS-4 catalyst, and 20 mL of isopropanol were weighed in a 50 mL reactor. The reactor was sealed, the air in the reactor was replaced three times with high-purity hydrogen, and 2.0 MPa of hydrogen was filled in. The reaction was carried out at 270 ° C for 4 h. After the reaction was completed and cooled to room temperature, the reaction solution was taken out and added with internal standard dimethyl phthalate. 1 mL of the reaction solution was analyzed by GC-MS-FID. The reaction solution was filtered to obtain a filtrate, and deionized water was added to 200 mL. The solution was allowed to stand for about 24 h to precipitate the unreacted lignin. After filtration and drying, the regenerated lignin was obtained.

[0149] The calculation results show that the conversion rate of lignin is 99.0%, the total yield of volatile products is 37.0%, and the yield and selectivity of saturated alcohol products are 29.2% and 79.0%, respectively.

[0150] Example 23: HRO5@CaTS-4 catalyzes lignin depolymerization

[0151] The difference between this embodiment and embodiment 5 is that:

[0152] (1) Lignin extraction: Weigh 10.0 g corn cob raw material, add 120 mL of extract solution to a 250 mL hydrothermal kettle, and place in an oven at 110°C for 4 h. After cooling to room temperature, filter and wash with ethanol. Collect the filtrate and washing solution, and add 500 mL of deionized water to precipitate lignin. After filtering through a 0.22 μm filter membrane, place in a fume hood to air dry, and grind into powder to obtain organic-soluble poplar lignin. The extract solution consists of 24 g of 98% concentrated sulfuric acid, 3200 mL of anhydrous ethanol, and 800 mL of deionized water.

[0153] (2) Catalytic depolymerization of lignin: 100 mg of the organic-soluble corncob lignin extracted in step (1), 120 mg of HRO5@CaTS-4 catalyst, and 20 mL of isopropanol were weighed in a 50 mL reactor. The reactor was sealed, the air in the reactor was replaced three times with high-purity hydrogen, and 2.0 MPa of hydrogen was filled in. The reaction was carried out at 270 ° C for 4 h. After the reaction was completed and cooled to room temperature, the reaction solution was taken out and added with internal standard dimethyl phthalate. 1 mL of the reaction solution was analyzed by GC-MS-FID. The reaction solution was filtered to obtain a filtrate, and deionized water was added to 200 mL. The solution was allowed to stand for about 24 h to precipitate the unreacted lignin. After filtration and drying, the regenerated lignin was obtained.

[0154] The calculation results show that the conversion rate of lignin is 94.5%, the total yield of volatile products is 32.5%, and the yield and selectivity of saturated alcohol products are 17.0% and 52.1%, respectively.

[0155] Example 24: HRO5-MgO 20 @TS-1 catalytic depolymerization of lignin

[0156] The difference between this embodiment and embodiment 9 is that:

[0157] (1) Lignin extraction: Weigh 10.0 g of rice straw raw material and 120 mL of extract solution, add them to a 250 mL hydrothermal kettle, and place in an oven at 110°C for 4 h. After cooling to room temperature, filter and wash with ethanol. Collect the filtrate and washing solution, and add 500 mL of deionized water to precipitate lignin. After filtering through a 0.22 μm filter membrane, place it in a fume hood to air dry, and grind it into powder to obtain organic-soluble rice straw lignin. The extract solution consists of 24 g of 98% concentrated sulfuric acid, 3200 mL of anhydrous ethanol, and 800 mL of deionized water.

[0158] (2) Catalytic depolymerization of lignin: 100 mg of the organically soluble rice straw lignin extracted in step (1), 100 mg of HRO5-MgO 20 Place @TS-1 catalyst and 20 mL of isopropanol in a 50 mL reactor. Seal the reactor, replace the air in the reactor with high-purity hydrogen three times, then fill it with 2.0 MPa of hydrogen. Reaction is continued at 270°C for 4 hours. After the reaction is complete and cooled to room temperature, remove the reaction solution and add dimethyl phthalate (as an internal standard). Analyze 1 mL of the reaction solution by GC-MS-FID. Filter the reaction solution to obtain a filtrate, add deionized water to 200 mL, and let it stand for approximately 24 hours to precipitate unreacted lignin. Filter and dry to obtain regenerated lignin.

[0159] The calculation results show that the conversion rate of lignin is 92.2%, the total yield of volatile products is 23.0%, and the yield and selectivity of saturated alcohol products are 15.8% and 68.5%, respectively.

[0160] As can be seen from the above examples, the present invention uses a modified molecular sieve-supported hydrated ruthenium-based catalytic system to achieve efficient and selective hydrogenolysis of lignin. Under the conditions of H2 pressure of 1 to 4 MPa, reaction temperature of 210 to 290°C, and reaction time of 2 to 6 hours, the conversion rate of lignin in this method can reach 88.6 to 99.0%, the total yield of volatile products can reach 23.0 to 46.0%, the yield of alcohol liquid fuel products can reach 9.33 to 31.9%, and the selectivity can reach 32.8 to 71.0%.

[0161] The modified molecular sieve-supported hydrated ruthenium catalyst used in the present invention has a simple preparation process, low environmental pollution, and achieves efficient and selective depolymerization of lignin under mild conditions. The saturated alcohol products have stable chemical properties and are alcoholic organic substances widely used in the fields of food, health products, cosmetics, etc. They can be used as organic reagents and can also be used to produce other chemicals, representing important chemical raw materials. In the pharmaceutical field, these saturated alcohol products are often used as pharmaceutical intermediates for organic synthesis. In addition, they can also serve as intermediates for the emerging cycloalkane biofuel and are attractive fuel blending agents in jet and naval fuels.

[0162] Chinese invention patent CN105152854A discloses a one-step method for converting lignin into liquid fuel. Lignin is used as the raw material, and a mixture of NaOH solution and low-carbon alcohols is used as a composite reaction solvent. A depolymerization reaction is then carried out in the presence of a hydrogenation catalyst. After the reaction, the mixture is neutralized with HCl solution and filtered. Ethyl acetate is added to the filtrate, which separates it into an aqueous phase and an oil phase. The oil phase is then subjected to rotary evaporation of ethyl acetate to obtain a liquid product of lignin degradation. This technical embodiment involves a sealed autoclave with nitrogen displacing the air inside. The reaction is carried out for 3 to 7 hours under conditions of a temperature of 200 to 240°C and a pressure of 4 to 7 MPa, ultimately yielding a lignin-derived liquid fuel. Although this technology can efficiently depolymerize lignin, the selectivity of alcohol products is low, and a large number of unsaturated small molecule products such as ketones and phenols are present in the products. At the same time, it uses a mixture of NaOH solution and low-carbon alcohols as a composite reaction solvent. On the one hand, the alkaline sodium hydroxide solution will cause certain corrosion to the reaction equipment (reactor), shortening the service life of the equipment. In addition, the treatment of the reaction liquid is complicated and tedious, and the discharge of waste liquid is likely to cause certain pollution to the environment, which also increases the cost of the process and the length of the preparation cycle.

[0163] Compared with Chinese invention patent CN118813294A, the technology of the present invention is a one-step catalytic lignin depolymerization reaction with relatively mild reaction conditions. It does not require pre-treatment of lignin to obtain lignin oil reaction raw materials. The process is simple and the preparation cycle is short, making it suitable for rapid industrial application.

[0164] Although Chinese invention patent application CN105152854A can convert lignin into liquid fuel in a one-step method, the sodium hydroxide in the composite solvent used can cause certain corrosion to reaction equipment (reactor), shortening the service life of the equipment, and its post-reaction treatment is complicated and cumbersome, and the waste liquid after the reaction needs additional treatment, which also increases the complexity and cost of the process. The present invention realizes selective depolymerization and efficient conversion of lignin in a shorter preparation cycle by a one-step hydrogenolysis reaction, and finally obtains highly selective saturated alcohol-based liquid oxygen-containing fuel. The present invention uses relatively green and environmentally friendly low-carbon alcohol solvents, and the raw material properties are stable, not easy to cause pollution to the environment, and the reaction subsequent treatment is simple.

[0165] The catalyst used in the present invention has a simple preparation process and relatively mild reaction conditions. It achieves efficient conversion of lignin within a relatively short preparation cycle by catalyzing the depolymerization reaction of lignin in one step, thereby obtaining a highly selective saturated alcohol-based liquid oxygen-containing fuel.

[0166] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A one-step catalytic method for preparing liquid oxygenated fuel by selective hydrogenolysis of lignin, characterized in that: After adding a modified molecular sieve-supported hydrated ruthenium catalyst and an alcohol solvent to organic soluble lignin, the mixture is reacted at an H2 pressure of 1 to 4 MPa and 210 to 290°C for 2 to 5 hours to obtain an alcohol-based liquid oxygen-containing fuel. The modified molecular sieve-supported hydrated ruthenium catalyst is expressed as HRO@CaTS-x, which consists of a carrier CaTS-x and an active component hydrated ruthenium HRO. HRO is a ruthenium complex composed of Ru(OH)3, RuO2 and bonded water molecules. x represents the molar ratio of Ca to Ti in the carrier, which is 2 to 16.

2. The method for preparing liquid oxygen-containing fuel by one-step catalytic selective hydrogenolysis of lignin according to claim 1, characterized in that: The preparation method of the hydrated ruthenium-based catalyst is as follows: fully dissolving hydrated ruthenium trichloride in deionized water, adding CaTS-x and stirring, adjusting the pH to 9-10, filtering after 3-5 hours, washing the filter cake and drying it to obtain a modified molecular sieve-supported hydrated ruthenium catalyst.

3. The method for preparing liquid oxygen-containing fuel by one-step catalytic selective hydrogenolysis of lignin according to claim 2, characterized in that: The CaTS-x is prepared by the following method: adding hydrochloric acid to deionized water to adjust the pH to 1-2, adding cetyltrimethylammonium bromide and calcium nitrate tetrahydrate, and fully dissolving them, adding tetraethyl silicate and tetrabutyl titanate dissolved in isopropyl alcohol, stirring and fully co-hydrolyzing them, adding tetrapropylammonium hydroxide to adjust the pH to 5-6, stirring until a gel is fully formed, standing and then hydrothermally crystallizing at 170-180° C., filtering the crystallized liquid, washing and drying the filter cake, and calcining in air to obtain CaTS-x; The pH value is adjusted to 9-10 by adding ammonia water; The filter cake is washed and then dried by washing the obtained filter cake with deionized water for 2 to 3 times and then drying it in an oven at 100 to 120°C.

4. The method for preparing liquid oxygen-containing fuel by one-step catalytic selective hydrogenolysis of lignin according to claim 3, characterized in that: The mass ratio of the hexadecyltrimethylammonium bromide, tetrapropylammonium hydroxide, tetraethyl silicate, calcium nitrate tetrahydrate and tetrabutyl titanate is 4:7:25:11:1 to 4:7:40:1:

1.

5. The method for preparing liquid oxygen-containing fuel by one-step catalytic selective hydrogenolysis of lignin according to claim 3, characterized in that: The stirring time until the gel is fully formed is 0.5 to 1 hour; the stirring time for the fully co-hydrolysis after stirring is 20 to 24 hours; the standing time is 6 to 12 hours; the hydrothermal crystallization is carried out in a hydrothermal kettle; the hydrothermal crystallization time is 2 to 3 days; The calcination is carried out in a muffle furnace at a temperature of 500-600° C. for 3-5 hours. The drying in the washing and drying is carried out in an oven at a drying temperature of 80 to 100° C. and a drying time of 10 to 12 hours.

6. The method for preparing liquid oxygen-containing fuel by one-step catalytic selective hydrogenolysis of lignin according to claim 1, characterized in that: The mass ratio of the lignin to the hydrated ruthenium-based catalyst is 1:0.6-1:1.4, and the mass ratio of the lignin to the alcohol solvent is 1:10-1:20; and the HRO loading accounts for 3-7wt.% of the total mass of the catalyst.

7. The method for preparing liquid oxygen-containing fuel by selective hydrogenolysis of lignin according to claim 1, characterized in that: The alcohol solvent is any one of methanol, ethanol and isopropanol.

8. The method for preparing liquid oxygen-containing fuel by one-step catalytic selective hydrogenolysis of lignin according to claim 1, characterized in that: The organosoluble lignin is obtained by the following method: adding lignin and an extract into a reactor, reacting at 100-120° C. for 2-6 hours, and then filtering and separating; adding deionized water to the filtrate, filtering to obtain a solid, and drying to obtain the organosoluble lignin; the extract is prepared by adding 3000-4000 mL of anhydrous ethanol and 800-1000 mL of deionized water to every 20-25 g of concentrated sulfuric acid, and adding 120-150 mL of the extract to every 10.0 g of the lignin raw material.

9. The method for preparing liquid oxygen-containing fuel by one-step catalytic selective hydrogenolysis of lignin according to claim 8, characterized in that: The lignin is derived from any one of bagasse, poplar, bamboo, straw and corn cob.

10. The method for preparing liquid oxygen-containing fuel by one-step catalytic selective hydrogenolysis of lignin according to claim 1, characterized in that: The liquid oxygen-containing fuel is one or more of cyclohexanol, 4-methylcyclohexanol, 4-ethylcyclohexanol and 4-propylcyclohexanol.

Images