A method for preparing biomass-based long-chain ethers

Abstract

The present application discloses a method for preparing biomass-based long-chain ethers, comprising the following steps: subjecting biomass materials to physical pulverization treatment and then steam explosion treatment, removing most of the lignin, and then performing drying treatment to obtain pretreated biomass; converting the pretreated biomass into an aqueous solution of mixed carbonyl compounds through a fluidized-catalytic reaction in a first inert gas environment, and then dehydrating the liquid product to obtain mixed carbonyl compounds; adding lower alcohols to the mixed carbonyl compounds, and in a second inert gas environment, adding a hydrogenation catalyst and an acid catalyst to convert the carbonyl compounds into saturated alcohols and then undergoing an etherification reaction; obtaining an etherification mixture after the etherification reaction is completed, separating the hydrogenation catalyst, the acid catalyst and the liquid-phase ether mixture in the etherification mixture, and distilling and purifying the ether mixture to finally obtain a long-chain ether mixture. It has many beneficial effects such as a short production process, low cost and wide application range.

Description

Technical Field

[0001] The present invention relates to the field of preparing mixtures of ether substances, and particularly to a method for preparing biomass-based long-chain ethers. Background Art

[0002] Diesel fuel, as one of the main fuels, is widely used in various fields. However, the environmental pollution problems caused by diesel combustion have always attracted people's attention. At present, there is a mature method of adding oxygen-containing additives to diesel fuel. This method effectively avoids local oxygen deficiency during the diffusion process of diesel fuel, thus better achieving complete combustion of diesel fuel and suppressing the emission of diesel pollutants. Among them, the new additive, long-chain ether substances, because of their physical and chemical properties similar to diesel fuel, require less modification work during the design of the feeding and combustion systems, so they are more favored. Traditional long-chain ether preparation technologies include five methods: direct etherification of alcohols, reductive etherification of carbonyl compounds and alcohols, furan solvent hydrogen supply etherification, acetalization of aldehydes and alcohols, and alkoxylation of epoxides and alcohols. All of them have certain application limitations.

[0003] First of all, direct etherification of alcohols means that two molecules of alcohol are dehydrated on a solid acid catalyst to form ether and water. The competitive reaction of direct etherification is the unimolecular dehydration of alcohol to form olefins, and olefins may further polymerize to form carbon deposits, resulting in catalyst deactivation. Moreover, the water generated by etherification will also have a negative impact on the reaction rate and product selectivity. In addition, the direct etherification method is only applicable to the production of symmetric ethers from linear alcohols, and its application range is relatively narrow.

[0004] Reductive etherification of carbonyl compounds and alcohols means that aldehydes or ketones react with alcohols under the combined action of external H2, a hydrogenation catalyst, and an acid catalyst to form ether and water. The reductive etherification reaction of aldehydes or ketones and alcohols can more flexibly select two reactants. Therefore, biomass-derived alcohols and carbonyl compounds can be fully utilized to synthesize various symmetric or asymmetric ethers. The disadvantage of the reductive etherification reaction is that it requires external H2 and noble metal catalysts.

[0005] The main difference between furan solvent hydrogen supply etherification and reductive etherification is that alcohol is used as the hydrogen donor instead of external H2. In this case, alcohol is both a solvent and a reactant, and the reaction conditions are milder. It is the most promising long-chain ether production process. However, at present, this method is mainly used to synthesize furan ethers and does not have high generality for other ether substances.

[0006] Acetalization of aldehydes and alcohols means that aldehydes react with alcohols under acid-catalyzed conditions to dehydrate to form acetals and water. For example, polyoxymethylene dimethyl ethers (PODE n ) widely studied at present are synthesized by the above method, but the production process route of this long-chain ether is relatively long.

[0007] The essence of the alkoxylation reaction between epoxides and alcohols is a ring-opening addition reaction. Alcohols (such as methanol, ethanol, and propanol) and epoxides (such as ethylene oxide and propylene oxide) can undergo alkoxylation reactions under the action of catalysts to prepare various long-chain ethers or alcohol ethers containing oxygen compounds, which have the advantages of high cetane number, high oxygen content, sulfur-free and aromatic-free, and physical and chemical properties close to diesel. However, there are also problems such as long production process routes and harsh reaction conditions.

[0008] The current biomass-based long-chain ether preparation process involves at least two platform compounds from biomass to long-chain ethers. Moreover, individual processes require conditions such as consuming external H2 and using noble metal catalysts, resulting in long process routes, harsh reaction conditions, and high production costs. Summary of the Invention

[0009] Technical problems to be solved:

[0010] The current biomass-based long-chain ether preparation methods have many problems such as narrow application scope, long production process routes, harsh preparation conditions, and high production costs. The purpose of the present invention is to provide a long-chain ether preparation method with a wide application scope, a short production process route, and low preparation conditions and costs.

[0011] Technical solution:

[0012] The present application discloses a method for preparing biomass-based long-chain ethers, which includes the following steps:

[0013] Step 1: Pretreatment of biomass materials: Physically decompose the biomass materials and then perform steam explosion treatment. After removing lignin with a proportion greater than 25% in the biomass materials, perform drying treatment to obtain pretreated biomass.

[0014] Step 2: Fluidization-catalysis treatment: Under the first environment of inert gas, convert the pretreated biomass into an aqueous solution of mixed carbonyl compounds through fluidization-catalysis reaction, and dehydrate the liquid product to obtain mixed carbonyl compounds.

[0015] Step 3: Etherification treatment: Add low-carbon alcohols to the mixed carbonyl compounds, and then under the second environment of inert gas, add a hydrogenation catalyst to cause the hydrogen in the low-carbon alcohols to add to the mixed carbonyl compounds to synthesize saturated alcohols, and at the same time add an acid catalyst to cause the saturated alcohols to undergo etherification reactions; after the etherification reaction is completed, obtain an etherification mixture, separate the hydrogenation catalyst, acid catalyst, and liquid-phase ether mixture in the etherification mixture, and distill and purify the ether mixture to finally obtain a long-chain ether mixture.

[0016] Preferably, the biomass material in step one is agricultural or forestry waste. The agricultural waste is straw and / or corncob, and the forestry waste is wood chips. The physical pulverization includes pulverizing the above biomass material into particles with a particle size range of 0.6 - 1.25 mm.

[0017] Preferably, the steam explosion treatment in step one is to perform steam explosion on the physically decomposed biomass material at a steam explosion pressure of 1.2 - 2.8 MPa, and the subsequent pressure holding time range is 1 - 5 min.

[0018] Preferably, the first inert gas environment in step two is a nitrogen or argon environment maintaining a flow rate of 0.8 L / min. The fluidization-catalytic reaction is a fluidized pyrolysis reaction with a pyrolysis temperature of 550°C and a fluidization medium of quartz sand, and a catalytic reaction carried out at a reaction temperature of 450°C with the addition of an Fe / CeO2 catalyst with a molar ratio range of 0.1 - 0.6. The biomass feed rate of this catalytic reaction is set to 20 g / h, and the mass space velocity range is 1 - 4 h -1 。

[0019] Preferably, the lower alcohols in step three include at least one of methanol, ethanol, propanol, butanol, isopropanol, and isobutanol. In the solution after mixing the lower alcohols with the mixed carbonyl compounds, the concentration range of carbonyl compounds is 1 - 6 mol / L.

[0020] Preferably, the second inert gas environment in step three is a nitrogen or argon environment maintaining a gas pressure of 2 MPa.

[0021] Preferably, the hydrogenation catalyst in step three is at least one of Cu / Char, Fe / Char, Ni / Char, Co / Char, Zr / Char, and Sn / Char, and the acid catalyst is at least one of H-Beta, HZSM-5, and Amberlyst-15.

[0022] Preferably, the metal ion loading amount range in the hydrogenation catalyst is 0.1 - 0.5 mol / L. The mass ratio range of the hydrogenation catalyst to the lower alcohols is 0.5 - 4%, and the mass ratio range of the acid catalyst to the lower alcohols is 0.5 - 4%.

[0023] Preferably, the etherification reaction in step three is to heat for 1 - 12 hours at a temperature of 120°C. Separating the hydrogenation catalyst, acid catalyst, and liquid-phase ether mixture from the etherification mixture is to cool the etherification mixture to precipitate the solid-phase hydrogenation catalyst and acid catalyst.

[0024] Preferably, the drying treatment temperature in step one is 105°C; the distillation and purification temperature in step three is 100°C.

[0025] Beneficial effects:

[0026] By successively performing pretreatment, fluidization-catalysis treatment, and final etherification treatment on waste biological materials, mixed long-chain ether substances are generated, which have many beneficial effects such as a short production process, low cost, and a wide application range. Description of the drawings

[0027] Figure 1 It is a flowchart of the detection method of this application;

[0028] Figure 2 It is a schematic structural diagram of the biomass-based long-chain ether preparation device in each embodiment of this application;

[0029] Figure 3 It is a graph showing the relationship between the mass yield of long-chain ether and the heating time during the etherification process in Example 1 of this application;

[0030] Description of reference numerals: Figure 2 In it, 1 is a steam generator, 2 is an air inlet device, 3 is a biomass feeding device, 4 is an explosion steaming device,

[0031] 5 is a fluidized bed reactor, 6 is a catalytic bed reactor, 7 is a condensation device, 8 is a gas collection device, 9 is an explosion steaming solution collection device,

[0032] 10 is a pyrolytic carbon collection device, 11 is a lower alcohol storage device, 12 is a dehydration device, 13 is a reaction kettle, 14 is a solid-liquid separation device,

[0033] 15 is a distillation device, 16 is a long-chain ether storage device, 17 is a catalyst storage device. Detailed implementation manners

[0034] The technical solutions of the present invention will be further described below with reference to the drawings.

[0035] As Figure 1 and Figure 2 shown, the specific experimental methods used in the following examples are as follows:

[0036] Step 1: First, at least one biomass material among straw, corn cobs, and wood chips is physically pulverized, and the particle size of the pulverized particles is controlled within the range of 0.6 - 1.25 mm; then it is added to the biomass feeding device 3 and automatically fed into the explosion steaming device 4, and the explosion steaming device 4 also includes a steam generator 1 for supplying steam; the explosion steaming pressure range of the explosion steaming device 4 is 1.2 - 2.8 MPa to perform steam explosion on the physically pulverized biomass particles, and the subsequent pressure holding time range is 1 - 5 min.

[0037] The biomass particles after steam explosion are subjected to drying treatment at 105 °C, wherein the liquid phase components are collected in the explosion steaming solution collection device 9, and the solid phase components enter the fluidized bed reactor 5.

[0038] Step 2: The fluidized bed reactor 5 is connected to the air inlet device 2, and the air inlet device 2 supplies nitrogen or argon; the solid-phase components entering the fluidized bed reactor 5 will be pyrolyzed at 550 °C in an environment of nitrogen or argon with a flow rate of 0.8 L / min and in an environment with quartz sand as the fluidization medium; the pyrolyzed carbon will be separated and stored in the pyrolyzed carbon collection device 10, and the remaining high-temperature gas-phase mixture rich in carbonyl compounds and nitrogen will enter the catalytic bed device 6.

[0039] In the catalytic bed device 6, a Fe / CeO2 catalyst with a molar ratio range of 0.1 - 0.6 is added, and the catalytic reaction is carried out at a reaction temperature of 450 °C with the biomass feeding rate set at 20 g / h and the mass space velocity in the range of 1 - 4 h -1 After the catalytic reaction, a mixture of inert gas and gaseous organic compounds is obtained. This high-temperature gas-phase mixture is condensed by the condensation device 7. The inert gas, which is difficult to condense, is collected and stored in the gas collection device 8. The remaining aqueous solution of various carbonyl compounds is transferred to the dehydration device 12 for dehydration treatment to obtain a mixed carbonyl compound.

[0040] Step 3: The obtained mixed carbonyl compound is placed into the reaction kettle 13, and nitrogen or argon maintained at a pressure of 2 Mpa is introduced through the air inlet device 2. At the same time, lower alcohols, a hydrogenation catalyst, and an acid catalyst are added through the lower alcohol storage device 11 and the catalyst storage device 17 respectively. The lower alcohol is at least one of methanol, ethanol, propanol, butanol, isopropanol, and isobutanol; in the solution obtained by mixing the lower alcohol and the mixed carbonyl compound, the concentration range of the carbonyl compound is 1 - 6 mol / L; the hydrogenation catalyst is at least one of Cu / Char, Fe / Char, Ni / Char, Co / Char, Zr / Char, and Sn / Char, and the metal ion loading range is 0.1 - 0.5 mol / L; the acid catalyst is at least one of H-Beta, HZSM-5, and Amberlyst-15, and the mass ratio of the sum of the hydrogenation catalyst and the acid catalyst to the mass of the lower alcohol ranges from 1 - 8%; then, it is heated at 120 °C for 1 - 12 hours for the etherification reaction. The product of the etherification reaction is subjected to solid-liquid separation by cooling. The two solid-phase catalysts are retained in the catalyst storage device 17 for recycling; after the liquid-phase etherification product undergoes a distillation and purification process at 100 °C in the distillation device 15, a mixed long-chain ether is finally obtained and stored in the long-chain ether storage device 16.

[0041] The mass yield of the long-chain ether is calculated by comparing the mass of the obtained mixed long-chain ether with the mass of the biomass material.

[0042] Example 1

[0043] (1) Biomass steam explosion pretreatment

[0044] In this example, the biomass raw material is corn straw. The explosion pressure is set to 1.2 MPa and the pressure holding time is 3 min. After the explosion, the solid residue is dried at 105 °C. At this time, the lignin removal rate is 55.19%, the lignin content in the exploded biomass is 9.97%, and the holocellulose content is 69.47%.

[0045] (2)Non-in-situ catalytic fast pyrolysis of exploded biomass

[0046] 5 g of exploded biomass is respectively loaded into the biomass feeding device, 20 g of quartz sand is loaded into the fluidized bed reactor, and 15 g of a solid-phase catalyst with a Fe / CeO2 molar ratio of 0.3 is loaded into the catalytic bed reactor. At this time, the biomass feeding rate of the catalytic bed is set to 20 g / h, and the WSHV is 1.33 h -1 The temperatures of the fluidized bed and the catalytic bed are respectively set to 550 °C and 450 °C, and the N2 flow rate is maintained at 0.8 L / min. After the reaction, the gaseous products are first condensed to remove inert gases, and then the condensed liquid products are dehydrated through a dehydration device to obtain a mixed carbonyl compound. The mass yield of the carbonyl compound is 28.91%, and the components are aldehydes, ketones, furfural, and 5-hydroxymethylfurfural;

[0047] (3)Solvent hydrogen-donating etherification of carbonyl compounds

[0048] 50 mL of an isopropanol / carbonyl compound mixed solution (where the carbonyl compound concentration is 4 mol / L), 0.5 g of H-Beta acid catalyst, and 0.5 g of Cu / Char hydrogenation catalyst are placed in a stainless-steel high-pressure batch reactor. After the reactor is sealed, it is repeatedly purged with high-purity N2 5 times to displace the air inside, and then N2 is filled to a pressure of 2 MPa. Then the reactor is heated to 120 °C and reacted for 1–12 h. After the reaction, the reactor is immediately cooled in ice water. After opening the reactor, the solid catalyst and the liquid product are separated by vacuum filtration. The liquid product is distilled and purified at 100 °C to obtain a long-chain ether mixture. The relationship between the mass yield of the long-chain ether and the reaction time is as Figure 3 shown.

[0049] Example 2

[0050] (1)Biomass explosion pretreatment

[0051] In this example, the biomass raw material is corn straw. The explosion pressure is set to 2 MPa and the pressure holding time is 3 min. After the explosion, the solid residue is dried at 105 °C. At this time, the lignin removal rate is 58.86%, the lignin content in the exploded biomass is 9.2%, and the holocellulose content is 71.57%.

[0052] (2)In-situ catalytic fast pyrolysis of steam-exploded biomass

[0053] 5 g of steam-exploded biomass was respectively loaded into the biomass feeding device, 20 g of quartz sand was loaded into the fluidized bed reactor, and 15 g of solid-phase catalyst with a Fe / CeO2 molar ratio of 0.3 was loaded into the catalytic bed reactor. At this time, the biomass feeding rate of the catalytic bed was set at 20 g / h, and the WSHV was 1.33 h -1 , the temperatures of the fluidized bed and the catalytic bed were respectively set at 550 °C and 450 °C, the N2 flow rate was maintained at 0.8 L / min. After the reaction, the gaseous products were first condensed to remove inert gases, and then the condensed liquid products were dehydrated through a dehydration device to obtain a mixed carbonyl compound. The mass yield of the carbonyl compound was 28.91%, and the components were aldehydes, ketones, furfural, and 5-hydroxymethylfurfural;

[0054] (3)Solvent hydrogen-donating etherification of carbonyl compounds

[0055] 50 mL of isopropanol / carbonyl compound mixed solution (where the concentration of the carbonyl compound was 4 mol / L), 0.5 g of H-Beta acid catalyst, and 0.5 g of Cu / Char hydrogenation catalyst were placed in a stainless-steel high-pressure batch reactor. After the reactor was sealed, it was repeatedly purged 5 times with high-purity N2 to displace the air inside, and then N2 was filled until the pressure reached 2 MPa. Then the reactor was heated to 120 °C and reacted for 12 h. After the reaction, the reactor was immediately cooled in ice water. After opening the reactor, the solid catalyst and the liquid product were separated by vacuum filtration. The liquid product was distilled and purified at 100 °C to obtain a long-chain ether mixture. The mass yield of the long-chain ether was 64.75%.

[0056] Example 3

[0057] (1)Biomass steam explosion pretreatment

[0058] In this example, the biomass raw material was corn straw. The steam explosion pressure was set at 2.8 Pa and the pressure holding time was 3 min. After the steam explosion, the solid residue was dried at 105 °C. At this time, the lignin removal rate was 26.37%, the lignin content in the steam-exploded biomass was 16.8%, and the holocellulose content was 62.67%;

[0059] (2)In-situ catalytic fast pyrolysis of steam-exploded biomass

[0060] 5 g of steam-exploded biomass was respectively loaded into the biomass feeding device, 20 g of quartz sand was loaded into the fluidized bed reactor, and 15 g of solid-phase catalyst with a Fe / CeO2 molar ratio of 0.3 was loaded into the catalytic bed reactor. At this time, the biomass feeding rate of the catalytic bed was set at 20 g / h, and the WSHV was 1.33 h -1, the temperatures of the fluidized bed and the catalytic bed were set at 550 °C and 450 °C respectively, the N2 flow rate was maintained at 0.8 L / min. After the reaction, the gaseous products obtained were first condensed to remove inert gases, and then the condensed liquid products were dehydrated through a dehydration device to obtain a mixed carbonyl compound. The mass yield of the carbonyl compound was 28.91%, and the components were aldehydes, ketones, furfural, and 5-hydroxymethylfurfural;

[0061] (3) Solvent hydrogen-donating etherification of carbonyl compounds

[0062] A 50 mL isopropanol / carbonyl compound mixed solution (where the concentration of the carbonyl compound was 4 mol / L), 0.5 g of H-Beta acid catalyst, and 0.5 g of Cu / Char hydrogenation catalyst were placed in a stainless-steel high-pressure batch reactor. After the reactor was sealed, it was repeatedly purged with high-purity N2 five times to displace the air inside, and then N2 was filled until the pressure reached 2 MPa. Then the reactor was heated to 120 °C and reacted for 12 h. After the reaction, the reactor was immediately cooled in ice water. After opening the reactor, the solid catalyst and the liquid product were separated by vacuum filtration. The liquid product was distilled and purified at 100 °C to obtain a long-chain ether mixture. The mass yield of the long-chain ether was 43.87%.

[0063] Example 4

[0064] (1) Biomass steam explosion pretreatment

[0065] In this example, the biomass raw material was corn straw. The steam explosion pressure was set at 2 MPa and the pressure holding time was 1 min. After the steam explosion, the solid residue was dried at 105 °C. At this time, the lignin removal rate was 62.54%, the lignin content in the steam-exploded biomass was 8.43%, and the holocellulose content was 72.94%;

[0066] (2) Non-in-situ catalytic fast pyrolysis of steam-exploded biomass

[0067] 5 g of steam-exploded biomass was respectively loaded into the biomass feeding device, 20 g of quartz sand was loaded into the fluidized bed reactor, and 15 g of a solid-phase catalyst with a Fe / CeO2 molar ratio of 0.3 was loaded into the catalytic bed reactor. At this time, the biomass feeding rate of the catalytic bed was set at 20 g / h, and the WSHV was 1.33 h -1 , the temperatures of the fluidized bed and the catalytic bed were set at 550 °C and 450 °C respectively, the N2 flow rate was maintained at 0.8 L / min. After the reaction, the gaseous products obtained were first condensed to remove inert gases, and then the condensed liquid products were dehydrated through a dehydration device to obtain a mixed carbonyl compound. The mass yield of the carbonyl compound was 28.91%, and the components were aldehydes, ketones, furfural, and 5-hydroxymethylfurfural;

[0068] (3) Solvent hydrogen-donating etherification of carbonyl compounds

[0069] 50 mL of isopropanol / carbonyl compound mixed solution (where the concentration of carbonyl compound is 4 mol / L), 0.5 g of H-Beta acid catalyst and 0.5 g of Cu / Char hydrogenation catalyst were placed in a stainless-steel high-pressure batch reactor. After the reactor was sealed, it was repeatedly purged with high-purity N2 for 5 times to displace the air inside, and then N2 was filled until the pressure reached 2 MPa. Then the reactor was heated to 120 °C and reacted for 12 h. After the reaction ended, the reactor was immediately cooled in ice water. After opening the reactor, the solid catalyst and liquid product were separated by vacuum filtration. The liquid product was distilled and purified at 100 °C to obtain a long-chain ether mixture, and the mass yield of the long-chain ether was 60.13%.

[0070] Example 5

[0071] (1) Biomass steam explosion pretreatment

[0072] In this example, the biomass raw material was corn straw. The steam explosion pressure was set at 2 MPa and the pressure holding time was 5 min. After the steam explosion, the solid residue was dried at 105 °C. At this time, the lignin removal rate was 48.83%, the lignin content in the steam-exploded biomass was 11.3%, and the holocellulose content was 73.14%;

[0073] (2) Non-in-situ catalytic fast pyrolysis of steam-exploded biomass

[0074] 5 g of steam-exploded biomass was respectively loaded into the biomass feeding device, 20 g of quartz sand was loaded into the fluidized bed reactor, and 15 g of solid catalyst with a molar ratio of Fe / CeO2 of 0.3 was loaded into the catalytic bed reactor. At this time, the biomass feeding rate of the catalytic bed was set at 20 g / h, and the WSHV was 1.33 h -1 , the temperatures of the fluidized bed and the catalytic bed were respectively set at 550 °C and 450 °C, the N2 flow rate was maintained at 0.8 L / min. After the reaction ended, the gaseous product was first condensed to remove inert gases, and then the condensed liquid product was dehydrated through a dehydration device to obtain a mixed carbonyl compound. The mass yield of the carbonyl compound was 28.91%, and the components were aldehydes, ketones, furfural and 5-hydroxymethylfurfural;

[0075] (3) Solvent hydrogen donor etherification of carbonyl compounds

[0076] Place 50 mL of an isopropanol / carbonyl compound mixed solution (where the concentration of the carbonyl compound is 4 mol / L), 0.5 g of H-Beta acid catalyst, and 0.5 g of Cu / Char hydrogenation catalyst into a stainless-steel high-pressure batch reactor. After the reactor is sealed, it is repeatedly purged with high-purity N2 five times to displace the air inside, and then N2 is filled until the pressure reaches 2 MPa. Then, the reactor is heated to 120 °C and reacted for 12 h. After the reaction is completed, the reactor is immediately cooled in an ice bath. After opening the reactor, the solid catalyst and the liquid product are separated by vacuum filtration. The liquid product is distilled and purified at 100 °C to obtain a long-chain ether mixture, and the mass yield of the long-chain ether is 61.55%.

[0077] Example 6

[0078] (1) Biomass steam explosion pretreatment

[0079] In this example, the biomass raw material is corn stover. The steam explosion pressure is set at 2 MPa and the pressure holding time is 3 min. After the steam explosion, the solid residue is dried at 105 °C. At this time, the lignin removal rate is 58.86%, the lignin content in the steam-exploded biomass is 9.2%, and the holocellulose content is 71.57%.

[0080] (2) Non-in-situ catalytic fast pyrolysis of steam-exploded biomass

[0081] Respectively load 5 g of steam-exploded biomass into the biomass feeding device, 20 g of quartz sand into the fluidized bed reactor, and 15 g of a solid-phase catalyst with a Fe / CeO2 molar ratio of 0.1 into the catalytic bed reactor. At this time, the biomass feeding rate of the catalytic bed is set at 20 g / h, and the WSHV is 1.33 h -1 , the temperatures of the fluidized bed and the catalytic bed are set at 550 °C and 450 °C respectively, and the N2 flow rate is maintained at 0.8 L / min. After the reaction is completed, the gaseous product obtained is first condensed to remove inert gases, and then the condensed liquid product is dehydrated through a dehydration device to obtain a mixed carbonyl compound. The mass yield of the carbonyl compound is 28.91%, and the components are aldehydes, ketones, furfural, and 5-hydroxymethylfurfural;

[0082] (3) Solvent hydrogen donor etherification of carbonyl compounds

[0083] Place 50 mL of an isopropanol / carbonyl compound mixed solution (where the concentration of the carbonyl compound is 4 mol / L), 0.5 g of H-Beta acid catalyst, and 0.5 g of Cu / Char hydrogenation catalyst into a stainless-steel high-pressure batch reactor. After the reactor is sealed, purge it with high-purity N2 repeatedly 5 times to displace the air inside, and then fill it with N2 to a pressure of 2 MPa. Then heat the reactor to 120 °C and react for 12 h. After the reaction is completed, immediately cool the reactor in ice water. After opening the reactor, separate the solid catalyst and the liquid product by vacuum filtration. The liquid product is distilled and purified at 100 °C to obtain a long-chain ether mixture, and the mass yield of the long-chain ether is 61.02%.

[0084] Example 7

[0085] (1) Biomass steam explosion pretreatment

[0086] In this example, the biomass raw material is corn straw. Set the steam explosion pressure to 2 MPa and the pressure holding time to 3 min. After the steam explosion, dry the solid residue at 105 °C. At this time, the lignin removal rate is 58.86%, the lignin content in the steam-exploded biomass is 9.2%, and the holocellulose content is 71.57%;

[0087] (2) Non-in-situ catalytic fast pyrolysis of steam-exploded biomass

[0088] Load 5 g of steam-exploded biomass into the biomass feeding device, 20 g of quartz sand into the fluidized bed reactor, and 15 g of a solid-phase catalyst with a Fe / CeO2 molar ratio of 0.6 into the catalytic bed reactor. At this time, set the biomass feeding rate of the catalytic bed to 20 g / h, and the WSHV is 1.33 h -1 , Set the temperatures of the fluidized bed and the catalytic bed to 550 °C and 450 °C respectively, keep the N2 flow rate at 0.8 L / min. After the reaction is completed, the gaseous product obtained is first condensed to remove inert gases, and then the condensed liquid product is dehydrated through a dehydration device to obtain a mixed carbonyl compound. The mass yield of the carbonyl compound is 28.91%, and the components are aldehydes, ketones, furfural, and 5-hydroxymethylfurfural;

[0089] (3) Solvent hydrogen-donating etherification of carbonyl compounds

[0090] 50 mL of isopropanol / carbonyl compound mixed solution (where the concentration of carbonyl compound is 4 mol / L), 0.5 g of H-Beta acid catalyst and 0.5 g of Cu / Char hydrogenation catalyst were placed in a stainless-steel high-pressure batch reactor. After the reactor was sealed, it was repeatedly purged with high-purity N2 for 5 times to displace the air inside, and then N2 was filled until the pressure reached 2 MPa. Then the reactor was heated to 120 °C and reacted for 12 h. After the reaction, the reactor was immediately cooled in ice water. After opening the reactor, the solid catalyst and liquid product were separated by vacuum filtration. The liquid product was distilled and purified at 100 °C to obtain a long-chain ether mixture, and the mass yield of the long-chain ether was 60.73%.

[0091] Example 8

[0092] (1) Biomass steam explosion pretreatment

[0093] In this example, the biomass raw material was corn straw. The steam explosion pressure was set at 2 MPa and the pressure holding time was 3 min. After the steam explosion, the solid residue was dried at 105 °C. At this time, the lignin removal rate was 58.86%, the lignin content in the steam-exploded biomass was 9.2%, and the holocellulose content was 71.57%.

[0094] (2) Non-in-situ catalytic fast pyrolysis of steam-exploded biomass

[0095] 5 g of steam-exploded biomass was respectively loaded into the biomass feeding device, 20 g of quartz sand was loaded into the fluidized bed reactor, and 15 g of solid-phase catalyst with a molar ratio of Fe / CeO2 of 0.3 was loaded into the catalytic bed reactor. At this time, the biomass feeding rate of the catalytic bed was set at 20 g / h, and WSHV was 4 h -1 , the temperatures of the fluidized bed and the catalytic bed were set at 550 °C and 450 °C respectively, the N2 flow rate was maintained at 0.8 L / min. After the reaction, the gaseous product obtained was first condensed to remove inert gases, and then the condensed liquid product was dehydrated through a dehydration device to obtain a mixed carbonyl compound. The mass yield of the carbonyl compound was 28.91%, and the components were aldehydes, ketones, furfural and 5-hydroxymethylfurfural;

[0096] (3) Solvent hydrogenation etherification of carbonyl compounds

[0097] Place 50 mL of an isopropanol / carbonyl compound mixed solution (where the concentration of the carbonyl compound is 4 mol / L), 0.5 g of H-Beta acid catalyst, and 0.5 g of Cu / Char hydrogenation catalyst into a stainless-steel high-pressure batch reactor. After sealing the reactor, purge it repeatedly with high-purity N2 five times to displace the air inside, and then fill it with N2 to a pressure of 2 MPa. Then heat the reactor to 120 °C and react for 12 h. After the reaction, immediately cool the reactor in ice water. After opening the reactor, separate the solid catalyst and the liquid product by vacuum filtration. The liquid product is distilled and purified at 100 °C to obtain a long-chain ether mixture, and the mass yield of the long-chain ether is 63.23%.

[0098] Example 9

[0099] (1) Biomass steam explosion pretreatment

[0100] In this example, the biomass raw material is corn stover. Set the steam explosion pressure to 2 MPa and the pressure holding time to 3 min. After the steam explosion, dry the solid residue at 105 °C. At this time, the lignin removal rate is 58.86%, the lignin content in the steam-exploded biomass is 9.2%, and the holocellulose content is 71.57%;

[0101] (2) Non-in-situ catalytic fast pyrolysis of steam-exploded biomass

[0102] Charge 5 g of steam-exploded biomass into the biomass feeding device, 20 g of quartz sand into the fluidized bed reactor, and 15 g of a solid-phase catalyst with an Fe / CeO2 molar ratio of 0.3 into the catalytic bed reactor. At this time, set the biomass feeding rate in the catalytic bed to 20 g / h, and the WSHV is 1 h -1 , set the temperatures of the fluidized bed and the catalytic bed to 550 °C and 450 °C respectively, keep the N2 flow rate at 0.8 L / min. After the reaction, the gaseous product obtained is first condensed to remove inert gases, and then the condensed liquid product is dehydrated through a dehydration device to obtain a mixed carbonyl compound. The mass yield of the carbonyl compound is 28.91%, and the components are aldehydes, ketones, furfural, and 5-hydroxymethylfurfural;

[0103] (3) Solvent hydrogenation etherification of carbonyl compounds

[0104] Put 50 mL of isopropanol / carbonyl compound mixed solution (where the concentration of the carbonyl compound is 4 mol / L), 0.5 g of H-Beta acid catalyst, and 0.5 g of Cu / Char hydrogenation catalyst into a stainless-steel high-pressure batch reactor. After the reactor is sealed, it is repeatedly purged with high-purity N2 for 5 times to displace the air inside, and then N2 is filled until the pressure reaches 2 MPa. Then the reactor is heated to 120 °C and reacted for 12 h. After the reaction is completed, the reactor is immediately cooled in ice water. After opening the reactor, the solid catalyst and the liquid product are separated by vacuum filtration. The liquid product is distilled and purified at 100 °C to obtain a long-chain ether mixture, and the mass yield of the long-chain ether is 65.91%.

Claims

1. A method for preparing biomass-based long-chain ethers, characterized in that, It includes the following steps: Step 1, pretreatment of biomass materials: Physically crush the biomass materials and then perform steam explosion treatment. After removing lignin with a proportion greater than 25% in the biomass materials, perform drying treatment to obtain pretreated biomass; Step 2, fluidization-catalysis treatment: Under the first environment of inert gas, convert the pretreated biomass into an aqueous solution of mixed carbonyl compounds through fluidization-catalysis reaction, and then dehydrate the liquid product to obtain mixed carbonyl compounds; among them, the fluidization-catalysis reaction is a fluidized pyrolysis reaction with a pyrolysis temperature of 550 °C and a fluidization medium of quartz sand carried out successively, and a catalytic reaction carried out at a reaction temperature of 450 °C by adding a Fe / CeO2 catalyst with a molar ratio range of 0.1 - 0.6; Step 3, etherification treatment: Add lower alcohols to the mixed carbonyl compounds, and then under the second environment of inert gas, add a hydrogenation catalyst to cause the addition of hydrogen in the lower alcohols and the mixed carbonyl compounds to synthesize saturated alcohols, and at the same time add an acid catalyst to cause the saturated alcohols to undergo etherification reaction; after the etherification reaction is completed, obtain an etherification mixture, separate the hydrogenation catalyst, acid catalyst and liquid-phase ether mixture in the etherification mixture, and distill and purify the ether mixture to finally obtain a long-chain ether mixture; among them, the hydrogenation catalyst is at least one of Cu / Char, Fe / Char, Ni / Char, Co / Char, Zr / Char, Sn / Char, and the acid catalyst is at least one of H-Beta, HZSM-5, Amberlyst-15.

2. The method for preparing long-chain ethers according to claim 1, wherein The biomass materials in Step 1 are agricultural or forestry waste. The agricultural waste is straw and / or corncob, and the forestry waste is wood chips; the physical crushing includes crushing the above biomass materials into a particulate state with a particle size range of 0.6 - 1.25 mm.

3. The method for preparing long-chain ethers according to claim 1, wherein The steam explosion treatment in Step 1 is to perform steam explosion on the physically decomposed biomass materials at a steam explosion pressure of 1.2 - 2.8 MPa, and the subsequent pressure holding time range is 1 - 5 min.

4. The method for preparing long-chain ethers according to claim 1, wherein In Step 2, the first inert gas environment is a nitrogen or argon environment with a flow rate of 0.8 L / min; the biomass feeding rate for this catalytic reaction is set to 20 g / h, and the mass space velocity ranges from 1 to 4 h -1 .

5. The method for preparing long-chain ethers according to claim 1, wherein The lower alcohols in Step 3 are at least one of methanol, ethanol, propanol, butanol, isopropanol, isobutanol; in the solution after mixing the lower alcohols and the mixed carbonyl compounds, the concentration range of carbonyl compounds is 1 - 6 mol / L.

6. The method for preparing long-chain ethers according to claim 1, characterized in that, The second environment of inert gas in Step 3 is a nitrogen or argon environment maintaining a gas pressure of 2 MPa.

7. The method for preparing long-chain ethers according to claim 1, characterized in that, The metal ion loading amount range of the hydrogenation catalyst is 0.1 - 0.5 mol / L; the mass ratio range of the hydrogenation catalyst to the lower alcohols is 0.5 - 4%, and the mass ratio range of the acid catalyst to the lower alcohols is 0.5 - 4%.

8. The method for preparing long-chain ethers according to claim 1, wherein The etherification reaction in Step 3 is to heat at a temperature of 120 °C for 1 - 12 hours; separating the hydrogenation catalyst, acid catalyst and liquid-phase ether mixture in the etherification mixture is to cool the etherification mixture to precipitate the solid-phase hydrogenation catalyst and acid catalyst.

9. The method for preparing long-chain ethers according to claim 1, wherein The drying treatment temperature in Step 1 is 105 °C; the distillation and purification temperature in Step 3 is 100 °C.

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