Continuous production method for preparing long-chain alkane intermediate from bio-based platform compound

Abstract

The invention discloses a continuous production method for preparing a long-chain alkane intermediate from a bio-based platform compound, and belongs to the technical field of preparation of bio-based long-chain alkanes. The method comprises the following steps: in a water phase, under the catalysis of a basic catalyst, performing aldol condensation reaction on a biomass-based furfural derivative, biomass-based levulinic acid and a derivative thereof to obtain a condensation solution; acidifying the condensation liquid with a sulfuric acid aqueous solution, carrying out solid-liquid separation to obtain a condensation intermediate solid and a mother solution, and returning the mother solution to prepare the sulfuric acid aqueous solution; drying and dehydrating the condensation intermediate solid; dissolving in a solvent to obtain a condensation intermediate solution; enabling the condensation intermediate solution to pass through two fixed bed Raney nickel reaction towers which are connected in series, and reacting with hydrogen under the action of a Raney nickel catalyst, so as to obtain a saturated long-chain alkane intermediate solution. The production process is continuous, the product quality is stable, and the method is suitable for large-scale production of long-chain alkane intermediates prepared from bio-based platform compounds as raw materials.

Description

Technical Field

[0001] The present invention belongs to the technical field of preparation of bio-based long-chain alkanes, and specifically relates to a continuous production method for preparing long-chain alkane intermediates from bio-based platform compounds. Background Art

[0002] Compared to other biomass-to-aviation fuel technologies, aqueous biomass-based aviation fuel synthesis offers unique advantages by addressing the challenges of high water content, heterogeneity, bioactivity, and high ash content in biomass. This aqueous biomass-based synthesis utilizes the hydrolysis of lignocellulose and hemicellulose in biomass to produce platform compounds such as sugars and their derivatives, such as furfural. These compounds are then condensed to extend the carbon chain. The condensation products are then hydrodeoxygenated to produce aviation fuel-like hydrocarbons, primarily composed of C8-C15 long-chain alkanes. This method produces high-quality bio-aviation fuel at a relatively low cost, promising promising large-scale, stable production.

[0003] Patent CN113444543A uses a batch reactor to carry out an aldol condensation reaction with lignocellulose-based furfural compounds and carbonyl compounds as raw materials. The reaction is carried out under base catalysis, at a reaction temperature of 0-100°C and a reaction time of 1-12 hours. After the aldol condensation reaction, the condensation product is dissolved in an oxygen-containing organic solvent and hydrogenated in a fixed-bed reactor using a nickel and silica composite as a catalyst. The hydrogenation reaction conditions are: 0-200°C, 0.5-15 MPaA, and a mass space velocity of 0.1 h. -1 ~10h -1 , the hydrogen-to-oil volume ratio is 50-3000.

[0004] Patent CN114891535B uses furfural and levulinic acid, prepared from agricultural and forestry waste, as raw materials to undergo an aldol condensation reaction in an alkaline environment. The resulting bio-jet fuel precursor is dispersed into the bio-jet fuel and fed into a continuous kettle-type hydrogenation and saturation reactor. The product then enters a fixed-bed reactor for hydrodeoxygenation, hydrocracking, and isomerization to produce the bio-jet fuel. Both the aldol condensation and hydrogenation saturation steps utilize kettle-type reactors, and the aldol condensation reaction is a batch process, resulting in relatively low production efficiency.

[0005] Patent CN102850157A proposes a one-step method for preparing long-chain alkanes using a multifunctional catalyst. The condensation product of furfural (or 5-hydroxymethylfurfural) and acetone is dissolved in a solvent such as methanol, ethanol, or ether, and hydrogenated under the catalysis of a metal (I)-metal (II)-solid acid three-center multifunctional catalyst. The reaction is carried out using a batch reactor or fixed-bed reaction method. The fixed-bed reaction uses a stainless steel tubular reactor with a hydrogen-nitrogen mixed pressure of 0.5 to 3 MPaA (hydrogen partial pressure of 0.2 to 1 MPaA). The temperature in the reactor is raised to 110 to 190°C, and the liquid phase space velocity is 0.5 to 10 h-1 .

[0006] Patent CN107400531 proposes a new route for synthesizing liquid chain hydrocarbon fuels from platform compounds based on lignocellulose. Using the aldol condensation product 5-methyl-3-(2-methylenefuranyl)-2(3H)-furanone as an example, the patent proposes a batch reactor and a fixed-bed reactor for hydrogenation reactions. The batch reactor reaction conditions are: 30°C to 300°C, a hydrogen pressure of 1MPaA to 10MPaA, and a reaction time of 3 to 12 hours; the fixed-bed reactor reaction conditions are: 80°C to 350°C, a hydrogen pressure of 1MPaA to 10MPaA, and a mass space velocity of 0.1 to 10.0h / min for the reaction material / catalyst. -1 .

[0007] Patent CN114907295A uses bio-based platform compound molecules as raw materials and employs a series of multi-stage stirred reactors. By gradually increasing the reaction temperature of the series reactors, the process achieves continuous production of bio-based long-chain alkane intermediates. The stirring action of the kettle reactor employed in this patent can cause back-mixing of the fluid within the kettle, and the catalyst also carries a certain risk of breakage during stirring within the kettle, potentially reducing the catalyst's reusable life.

[0008] In summary, based on currently published patents, the aldol condensation reaction of bio-based platform compounds, such as biomass-based furfural derivatives and biomass-based levulinic acid and its derivatives, is generally performed using a tank reactor. However, batch production in a tank reactor has a low degree of automation, making it difficult to maintain high product quality due to multiple batch reactions. Furthermore, mixing efficiency is low, reaction times are long, and large-scale production can lead to stability issues in the agitator system. Continuous large-scale production using tandem tank reactors can also result in varying degrees of material backmixing, and the equipment requires a large footprint and high investment costs. Furthermore, the hydrogenation of condensation intermediates using a tank reactor requires the use of a solid catalyst such as Raney nickel. Using a tank reactor carries the risk of catalyst breakage during the stirring process, potentially reducing the catalyst's reusability. While existing patents have proposed fixed-bed reactors for hydrogenating condensation intermediates, they lack detailed descriptions of the fixed-bed reactor's structure and catalyst loading method.

[0009] To this end, the present invention proposes a continuous production method for preparing long-chain alkane intermediates from bio-based platform compounds. Summary of the Invention

[0010] In view of the shortcomings of the prior art, the purpose of the present invention is to provide a continuous production method for preparing long-chain alkane intermediates from bio-based platform compounds, which solves the problems in the prior art.

[0011] The purpose of the present invention can be achieved through the following technical solutions:

[0012] A continuous production method for preparing long-chain alkane intermediates from bio-based platform compounds comprises the following steps:

[0013] In an aqueous phase, under the catalysis of an alkaline catalyst, a biomass-based furfural derivative and a biomass-based levulinic acid and its derivatives undergo an aldol condensation reaction to obtain a condensation liquid;

[0014] The condensation liquid is acidified with a sulfuric acid aqueous solution, and the condensation intermediate is precipitated from the aqueous solution, and then the condensation intermediate solid and mother liquor are obtained by solid-liquid separation, and the mother liquor is used to return to prepare the sulfuric acid aqueous solution; the condensation intermediate solid is then dried and dehydrated;

[0015] The dried and dehydrated condensation intermediate solid is dissolved in a solvent to obtain a condensation intermediate solution;

[0016] The condensation intermediate solution is passed through two fixed-bed Raney nickel reaction towers connected in series, and reacts with hydrogen under the action of Raney nickel catalyst to obtain a saturated long-chain alkane intermediate solution.

[0017] Furthermore, the biomass-based furfural derivatives include: furfural-based compounds obtained by dehydration and hydrolysis of hemicellulose and cellulose;

[0018] The biomass-based levulinic acid is levulinic acid prepared by acid-catalyzed hydrolysis of cellulose as a raw material; the derivative of the biomass-based levulinic acid is levulinic acid ester;

[0019] The alkaline catalyst is NaOH or KOH.

[0020] Furthermore, the concentration of the biomass-based furfural derivative is 60wt% to 90wt%, the concentration of the alkaline catalyst is 2wt% to 10wt%; and the molar ratio of the biomass-based furfural derivative to biomass-based levulinic acid and its derivatives is 1 to 2:1.

[0021] Furthermore, static mixing internal components and tube wall flow-disturbing internal components are arranged in the tubular reactor.

[0022] Furthermore, the condensation liquid is acidified with 8 wt % sulfuric acid aqueous solution; the pH of the condensation liquid after acidification is 3-5.

[0023] Furthermore, the solvent is methanol, ethanol or tetrahydrofuran, and the concentration of the condensation intermediate in the condensation intermediate solution is 0.5 wt% to 50 wt%.

[0024] Furthermore, the fixed-bed Raney nickel reaction tower is provided with two-stage fixed bed layers for loading Raney nickel catalyst, and a liquid redistributor is provided between the fixed bed layers.

[0025] Further, the Raney nickel catalyst contains 25-35wt% of Ni.

[0026] Further, in the fixed bed Raney nickel reactor, hydrogen is fed from the bottom to maintain the hydrogen pressure in the reactor at 0.5-3MPaA; the hydrogen extracted from the top of the first fixed bed Raney nickel reactor is compressed by a hydrogen compressor and then sent to the second fixed bed Raney nickel reactor for reuse.

[0027] Further, the fixed bed Raney nickel reactor is heated by an outer jacket or an inner coil, the temperature of the first fixed bed Raney nickel reactor is 100-140℃, and the temperature of the second fixed bed Raney nickel reactor is 140-180℃.

[0028] The present application has the following advantages:

[0029] 1. The present application uses biomass-based furfural derivatives and biomass-based levulinic acid and its derivatives as raw materials, proposes a three-stage series tubular reactor for aldol condensation reaction, and sets static mixing internal components and pipe wall disturbance internal components in the reactor to strengthen the reaction process. The use of a tubular reactor can effectively enhance the reaction rate, reduce the reaction volume, reduce the equipment investment, and enhance the operation safety of the reaction system. The condensation intermediates obtained by aldol condensation are subjected to acidification, solid-liquid separation, drying, and redissolution, and then sent to a fixed bed reactor for saturated hydrogenation reaction. The whole system can be continuously and stably, safely and reliably operated, and the shortcomings of the prior art route that cannot be continuously operated are changed.

[0030] 2. The present application designs a fixed bed Raney nickel reactor with an outer jacket for saturated hydrogenation of the condensation intermediates, and the two-stage fixed bed Raney nickel reactors are operated in series, and the saturated long-chain alkanes are collected from the bottom of the second reactor. Compared with the full-mixed flow reactor of the prior art route, the fixed bed reactor eliminates the solid-liquid separation step of the reaction products, avoids the wear and loss of the catalyst in the stirring state, and makes the hydrogenation operation suitable for large-scale continuous production.

[0031] 3. The production process proposed by the present application is continuous, the product quality is stable, the equipment occupies a small area, the equipment investment is low, and it is suitable for large-scale production of long-chain alkane intermediates using biomass-based platform compounds as raw materials. BRIEF DESCRIPTION OF DRAWINGS

[0032] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed to be used in the embodiments or the prior art description will be briefly introduced below, and obviously, other drawings can also be obtained by those skilled in the art without creative labor.

[0033] Figure 1 is a continuous production process route of the present application;

[0034] Figure: 1-1, primary tubular reactor, 1-2, secondary tubular reactor, 1-3, tertiary tubular reactor, 2, buffer modification kettle, 3, condensation liquid delivery pump, 4, condensation liquid filter, 5, drying kiln, 6, dissolution kettle, 7, dissolution liquid delivery pump, 8-1, primary fixed bed Raney nickel reaction tower, 8-2, secondary fixed bed Raney nickel reaction tower, 9, hydrogen compressor, 10, reaction liquid delivery pump. DETAILED DESCRIPTION

[0035] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0036] As shown in the figure, a continuous production method for preparing long-chain alkane intermediates from a biomass-based platform compound comprises the following steps: Figure 1

[0037] S1, in an aqueous phase, under the catalysis of an alkaline substance, in a condensation reactor, a biomass-based furfural derivative and a biomass-based levulinic acid and its derivatives are subjected to a hydroxy aldehyde condensation reaction to obtain a condensation liquid (C10-C20 oxygen-containing compound); wherein the condensation reactor adopts a three-stage series tubular reactor (i.e., a primary tubular reactor 1-1, a secondary tubular reactor 1-2, and a tertiary tubular reactor 1-3 connected in series), static mixing internal components and pipe wall turbulence internal components are arranged in the tubular reactor; the condensation reaction conditions are as follows: 20-100℃, 0.2-0.5MPaA, and the total residence time of the material in the three-stage series tubular reactor is 0.5-2h.

[0038] S2, after the hydroxy aldehyde condensation reaction is completed, the condensation liquid is delivered to a buffer modification kettle 2, 8wt% sulfuric acid aqueous solution is added to the buffer modification kettle 2 to adjust the pH of the condensation liquid to 3-5, and a suspended precipitate is generated; the acidified condensation liquid is pumped into a condensation liquid filter 4 for solid-liquid separation by a condensation liquid delivery pump 3, to obtain a condensation intermediate solid and a mother liquor, and the mother liquor is returned to be used for preparing an 8% sulfuric acid aqueous solution; then the condensation intermediate solid is sent to a drying kiln 5 for drying and dehydration at 100-200℃, to ensure that the water content in the dried solid material is ≤2wt%;

[0039] S3, the dried and dehydrated condensation intermediate solid is delivered to a dissolution kettle 6 and dissolved by adding a solvent, to obtain a condensation intermediate solution; wherein the solvent is methanol, ethanol or tetrahydrofuran, and the condensation intermediate concentration in the condensation intermediate solution is 0.5wt%-50wt%.

[0040] ​S4, the condensation intermediate solution is fed from the top of the first fixed bed Raney nickel reactor 8-1 by the dissolving liquid delivery pump 7, and the condensation intermediate solution is hydrogenated under the action of the Raney nickel catalyst to obtain a reaction liquid, which is collected from the bottom of the first fixed bed Raney nickel reactor 8-1, and then is sent into the second fixed bed Raney nickel reactor 8-2 by the reaction liquid delivery pump 10, and the condensation intermediate which is not completely reacted continues to be hydrogenated under the action of the Raney nickel catalyst to obtain a saturated long-chain alkane intermediate solution, which is collected from the bottom of the second fixed bed Raney nickel reactor 8-2;

[0041] In the first fixed bed Raney nickel reactor 8-1 and the second fixed bed Raney nickel reactor 8-2, the hydrogen gas is fed from the bottom to maintain the hydrogen pressure in the reactor at 0.5-3 MPaA, and the hydrogen gas collected from the top of the first fixed bed Raney nickel reactor 8-1 is compressed by the hydrogen compressor 9 and then is recycled to the second fixed bed Raney nickel reactor 8-2. The temperature of the fixed bed Raney nickel reactor is 100-200℃.

[0042] In S1, the biomass-based furfural derivative is a biomass-based furfural derivative (5-hydroxymethylfurfural, furfural, etc.) obtained by dehydration and hydrolysis of hemicellulose and cellulose; the biomass-based levulinic acid is levulinic acid prepared by acid-catalyzed hydrolysis of cellulose, and the derivative of the biomass-based levulinic acid is levulinic acid ester (such as methyl levulinate, ethyl levulinate, etc.) obtained by esterification of levulinic acid.

[0043] In S1, the catalyst for the aldol condensation reaction is NaOH or KOH, and the concentration of the catalyst in the aldol condensation reaction liquid is 1.1-1.5 wt%. Preferably, the aldol condensation reaction temperature is 20-50℃, the total residence time of the materials in the three-stage tubular reactor is 1-1.5 h, and the operating pressure is 0.25-0.4 MPaA.

[0044] In S1, during the aldol condensation reaction, the concentration of the biomass-based furfural derivative is 60 wt%-90 wt%, the concentration of the biomass-based levulinic acid or its derivative is 2 wt%-10 wt%, and the concentration of the catalyst (catalyst raw material prepared before the reaction) is 2 wt%-10 wt%.

[0045] In S1, the molar ratio of the biomass-based furfural derivative to the biomass-based levulinic acid and its derivative is 1-2:1.

[0046] In S1, the tubular reactor is a horizontal tubular reactor, the inner diameter of the tubular reactor is 1-50 mm, and the first-stage tubular reactor 1-1 is provided with a static mixing internal component at the inlet, and the type of the mixing internal component is one or more of an SV type static mixer, an SL type static mixer, and an SX type static mixer, and the length is 500-1500 mm.

[0047] In S1, the tubular reactor is provided with a baffle plate type inner member for disturbing the tube wall.

[0048] Preferably, in S2, the pH of the condensation solution is adjusted to 3.5-4; the drying kiln 5 is a rotary drying kiln, the drying kiln is continuously operated, the operating pressure is normal pressure, the operating temperature is 100-130℃, and the residence time is 0.5-2h.

[0049] Preferably, in S3, the solvent is methanol, the concentration of the condensation intermediate in the condensation intermediate solution is 10wt%-30wt%, and the operating conditions of the dissolving kettle 6 are 0.1-0.2MPa and 20-50℃.

[0050] Further, in S4, the fixed bed Raney nickel reaction tower is provided with two-stage fixed bed layers loaded with Raney nickel catalyst, and a liquid redistributor is arranged between the fixed bed layers.

[0051] In S4, the diameter of the Raney nickel reaction tower is 125mm-250mm, the length-diameter ratio is 4-10, and the material is 316L.

[0052] In S4, the content of Ni in the Raney nickel catalyst is 25-35wt%.

[0053] Preferably, in S4, the flowing mode of the hydrogen and the reaction liquid is countercurrent, the hydrogen is compressed by the hydrogen compressor 9, and the pressure is increased to 1.2-3.2MPaA.

[0054] Preferably, in S4, the fixed bed Raney nickel reaction tower is designed with an outer jacket for heating, the operating conditions are as follows: the temperature of the first-stage fixed bed Raney nickel reaction tower is 100-140℃, and the temperature of the second-stage fixed bed Raney nickel reaction tower is 140-180℃, and the reaction pressure is 1-3MPaA (there is a resistance drop in the pipeline, valve and the like between the outlet of the compressor and the reaction tower, so the outlet pressure of the compressor is higher than that of the reaction tower).

[0055] The present application is further illustrated by the following examples, but is not limited to the following examples. The process is described in detail by taking 80% furfural and 5% levulinic acid as raw materials, and the equipment and chemicals used in the present application are conventional commercially available products in the technical field.

[0056] The process flow of the present application is as follows Figure 1As shown, the feed pipelines for furfural solution, levulinic acid solution, and sodium hydroxide solution are directly connected to the internal components of the static mixer at the inlet of the first-stage tubular reactor 1-1. Tubular reactors 1-1, 1-2, and 1-3 are connected in series. The outlet of the third-stage tubular reactor 1-3 is directly connected to the buffer modification kettle 2, which is equipped with a dilute sulfuric acid feed pipeline and a stirring device. The buffer modification kettle discharge pipeline is connected to the condensation liquid delivery pump 3, the delivery pump outlet is directly connected to the condensation liquid filter 4, and the filter mother liquor outlet pipeline is connected to the 8% sulfuric acid preparation section. The solid material outlet is connected to a drying kiln, and the drying kiln outlet pipeline is connected to the feed inlet of the dissolution kettle 6, which is also equipped with a methanol feed pipeline. The dissolving liquid outlet of the dissolving kettle 6 is connected to the dissolving liquid delivery pump 7, the pump outlet is connected to the top feed port of the first-stage fixed-bed Raney nickel reaction tower 8-1, the reaction liquid outlet of the reaction tower 8-1 is connected to the top feed port of the second-stage fixed-bed Raney nickel reaction tower 8-2 via the reaction liquid delivery pump 10, the top gas phase outlet of the first-stage fixed-bed Raney nickel reaction tower 8-1 is connected to the hydrogen compressor 9, the compressor outlet pipeline is connected to the bottom gas phase inlet of the second-stage fixed-bed Raney nickel reaction tower 8-2, and the bottom gas phase inlet of the second-stage fixed-bed Raney nickel reaction tower 8-2 is also designed with a hydrogen supplement pipeline. The top gas phase outlet pipeline of the second-stage fixed-bed Raney nickel reaction tower 8-2 is connected to the gas phase inlet at the bottom of the tower, and the tower kettle is provided with an outlet for saturated long-chain alkane intermediate products.

[0057] Example 1

[0058] 1) An 80% furfural solution, a 5% levulinic acid solution, and a 5% sodium hydroxide solution are directly introduced into a first-stage tubular reactor 1-1 at feed rates of 20.0 kg / h, 180.4 kg / h, and 74.7 kg / h, respectively. An SV-type static mixer is installed at the feed inlet of the first-stage tubular reactor 1-1, and baffled internals are installed within tubular reactors 1-1, 1-2, and 1-3. An aldol condensation reaction occurs within the tubular reactor at a reaction pressure of 0.6 MPa and a reaction temperature of 20°C. The residence time of the materials in the three-stage series tubular reactor is 1.5 hours.

[0059] (2) The condensation liquid prepared in step (1) flows continuously by gravity into the modified buffer kettle 2, and an 8% sulfuric acid aqueous solution is added to the kettle to maintain the pH of the condensation liquid in the kettle at 4. The condensation intermediate precipitates under acidic conditions. The condensation intermediate suspension in the modified buffer kettle is pumped into the condensation liquid filter 4 by the condensation liquid delivery pump 3. The filtered mother liquor is transported to the sulfuric acid preparation section for application, and the solid material is automatically unloaded to the feed port of the drying kiln 5. The material stays in the drying kiln for 30 minutes, the operating pressure is normal pressure, the operating temperature is 130°C, the extraction rate of the condensation solid material after drying is 22.30 kg / h, the moisture content is 1.7%, and the calculated condensation solid yield is 95.4% (the mass ratio of the condensation solid to the theoretical condensation solid generated by the added levulinic acid, the same below).

[0060] (3) The condensation intermediate obtained in step (2) was dissolved in methanol in dissolving tank 6, and the solvent methanol was added at a rate of 46.59 kg / h, and the mass concentration of the condensation intermediate in the solution was 32%.

[0061] (4) The condensation intermediate solution prepared in step (3) was transported from the dissolving tank by dissolving liquid pump 7 at a rate of 68.89 kg / h to first-stage fixed-bed Raney nickel reaction tower 8-1 (fixed-bed Raney nickel reaction tower 8-1, 8-2: Ф150 mm x 1200 mm; material: 316L; catalyst filling amount: 18 L of Raney nickel catalyst). Both the fixed-bed Raney nickel reaction towers 8-1, 8-2 were provided with two-stage fixed-bed layers, and a liquid redistributor was arranged between the fixed-bed layers, and the space velocity of the reaction liquid was 5 h -1 . The condensation intermediate was reacted with hydrogen in countercurrent in the two-stage Raney nickel reaction towers in series, the hydrogen was collected from the top of the first-stage fixed-bed Raney nickel reaction tower 8-1, was compressed by hydrogen compressor 9, and was used for the second-stage fixed-bed Raney nickel reaction tower 8-2. A hydrogen supplement pipeline was arranged at the tower bottom of the second-stage fixed-bed Raney nickel reaction tower 8-2, and the hydrogen pressure at the top of the first-stage fixed-bed Raney nickel reaction tower 8-1 was automatically controlled to be 1 MPaA. The saturated long-chain alkane intermediate product was collected from the tower bottom of the second-stage fixed-bed Raney nickel reaction tower 8-2; the collection rate was 69.75 kg / h, and the yield of the saturated long-chain alkane intermediate product was detected to be 93.9% (the same below). Both the two-stage reaction towers were provided with a jacket, steam was introduced into the jacket for heating, and the operating temperature was 120°C for the first-stage fixed-bed Raney nickel reaction tower and 170°C for the second-stage fixed-bed Raney nickel reaction tower.

[0062] Example 2

[0063] (1) 80% Furfural solution, 5% levulinic acid solution, and 5% sodium hydroxide were directly introduced into the first-stage tubular reactor 1-1 at a rate of 20.0 kg / h, 180.4 kg / h, and 74.7 kg / h, respectively. An SV type static mixer was arranged at the inlet of the first-stage tubular reactor 1-1, and baffle plate type internal components were arranged in the tubular reactors 1-1, 1-2, and 1-3. The aldol condensation reaction occurred in the tubular reactors, the reaction pressure was 0.6 MPa, the reaction temperature was 20°C, and the residence time of the material in the tubular reactors was 1 h.

[0064] (1) The condensation liquid prepared in step (1) flows continuously by gravity into the modified buffer kettle 2, and an 8% sulfuric acid aqueous solution is added to the kettle to maintain the pH of the condensation liquid in the kettle at 4. The condensation intermediate precipitates under acidic conditions. The condensation intermediate suspension in the modified buffer kettle is pumped into the condensation liquid filter 4 by the condensation liquid delivery pump 3. The filtered mother liquor is transported to the sulfuric acid preparation section for application, and the solid material is automatically unloaded to the feed port of the drying kiln 5. The material stays in the drying kiln for 30 minutes, the operating pressure is atmospheric pressure, the operating temperature is 130°C, the extraction rate of the condensation solid material after drying is 21.60 kg / h, the moisture content is 1.8%, and the calculated condensation solid yield is 92.3%.

[0065] (2) The condensation intermediate obtained in step (2) was dissolved in methanol in a dissolving vessel 6, with the addition rate of the solvent methanol being 45.07 kg / h. The mass concentration of the condensation intermediate in the solution was 32.0%.

[0066] (4) The condensation intermediate solution prepared in step (3) is delivered to a fixed-bed Raney nickel reaction tower 8-1 (fixed-bed Raney nickel reaction towers 8-1 and 8-2, specifications: Ø150 mm × 1200 mm; material: 316L; catalyst filling amount: Raney nickel catalyst 18L) at a rate of 66.67 kg / h by a dissolving liquid delivery pump 7. The fixed-bed Raney nickel reaction towers 8-1 and 8-2 are both provided with two-stage fixed bed layers, with a liquid redistributor provided between the fixed bed layers. The reaction liquid space velocity is 4.71 h -1 . The condensation intermediate reacts with hydrogen in a countercurrent manner in a two-stage Raney nickel reaction tower connected in series. The hydrogen is extracted from the top of the first-stage fixed-bed Raney nickel reaction tower 8-1, compressed by the hydrogen compressor 9, and then reused in the second-stage fixed-bed Raney nickel reaction tower 8-2. A hydrogen supplement pipeline is provided at the kettle of the second-stage fixed-bed Raney nickel reaction tower 8-2, which automatically controls the hydrogen pressure at the top of the first-stage fixed-bed Raney nickel reaction tower 8-1 to 1MPaA. The saturated long-chain alkane intermediate product is extracted from the kettle of the second-stage fixed-bed Raney nickel reaction tower at a extraction rate of 67.50kg / h. The yield of the saturated long-chain alkane intermediate product is detected to be 93.6%. The outside of the two-stage reaction tower is provided with a jacket, and steam is introduced into the jacket for heating. The operating temperature is 120°C for the first-stage fixed-bed Raney nickel reaction tower and 170°C for the second-stage fixed-bed Raney nickel reaction tower.

[0067] Example 3

[0068] (1) 80% furfural solution, 5% levulinic acid solution, and 5% sodium hydroxide were directly introduced into a primary tubular reactor 1-1 at feed rates of 20.0 kg / h, 180.4 kg / h, and 74.7 kg / h, respectively. An SV-type static mixer was installed at the feed port of the primary tubular reactor 1-1, and no internal components were installed in the tubular reactor. An aldol condensation reaction occurred in the tubular reactor at a reaction pressure of 0.6 MPa and a reaction temperature of 30°C. The material residence time in the tubular reactor was 1 h, and the condensation liquid withdrawal rate was 275.1 kg / h.

[0069] (2) The condensation liquid prepared in step (1) flows continuously by gravity into the modified buffer kettle 2, and an 8% sulfuric acid aqueous solution is added to the kettle to maintain the pH of the condensation liquid in the kettle at 4. The condensation intermediate precipitates under acidic conditions. The condensation intermediate suspension in the modified buffer kettle is pumped into the condensation liquid filter 4 by the condensation liquid delivery pump 3. The filtered mother liquor is transported to the sulfuric acid preparation section for application, and the solid material is automatically unloaded to the drying kiln feed port. The material stays in the drying kiln for 30 minutes, the operating pressure is atmospheric pressure, the operating temperature is 130°C, the extraction rate of the condensation solid material after drying is 20.41 kg / h, the moisture content is 1.8%, and the calculated condensation solid yield is 87.2%.

[0070] (3) The condensation intermediate obtained in step (2) was dissolved in methanol in a dissolving vessel 6, with the addition rate of the solvent methanol being 42.58 kg / h. The mass concentration of the condensation intermediate in the solution was 32%.

[0071] (4) The condensation intermediate solution prepared in step (3) is delivered to a fixed-bed Raney nickel reaction tower 8-1 at a rate of 62.99 kg / h by a dissolving liquid delivery pump 7 (specifications of fixed-bed Raney nickel reaction towers 8-1 and 8-2: Ø150 mm × 1200 mm; material: 316 L; catalyst filling amount: Raney nickel catalyst 18 L). The fixed-bed Raney nickel reaction towers 8-1 and 8-2 are both equipped with two fixed bed layers, with a liquid redistributor between the fixed bed layers. The reaction liquid space velocity is 4.45 h -1 . The condensation intermediate reacts with hydrogen in a countercurrent manner in a two-stage Raney nickel reaction tower connected in series. The hydrogen is extracted from the top of the first-stage fixed-bed Raney nickel reaction tower 8-1, compressed by the hydrogen compressor 9, and then reused in the second-stage fixed-bed Raney nickel reaction tower 8-2. A hydrogen supplement pipeline is provided at the kettle of the second-stage fixed-bed Raney nickel reaction tower 8-2, which automatically controls the hydrogen pressure at the top of the first-stage fixed-bed Raney nickel reaction tower 8-1 to 1MPaA. The saturated long-chain alkane intermediate product is extracted from the kettle of the second-stage fixed-bed Raney nickel reaction tower at a extraction rate of 63.77kg / h. The yield of the saturated long-chain alkane intermediate product is detected to be 93.4%. The outside of the two-stage reaction tower is provided with a jacket, and steam is introduced into the jacket for heating. The operating temperature is 120°C for the first-stage fixed-bed Raney nickel reaction tower and 170°C for the second-stage fixed-bed Raney nickel reaction tower.

[0072] Example 4

[0073] (1) The hydroxy aldehyde condensation reaction process is the same as that of Example 1.

[0074] (2) The solid condensate preparation process is the same as that of Example 1.

[0075] (3) The condensate solution preparation process is the same as that of Example 1.

[0076] (4) The condensation intermediate solution prepared in step (3) is delivered by the dissolving liquid delivery pump 7 to the first fixed bed Raney nickel reaction tower 8-1 (fixed bed Raney nickel reaction tower 8-1, 8-2 specifications: Ф150mm x 1200mm; material: 316L; catalyst filling amount: Raney nickel catalyst 18L) at a rate of 68.89kg / h. The fixed bed Raney nickel reaction tower 8-1, 8-2 is provided with two fixed bed layers, and a liquid redistributor is arranged between the fixed bed layers. The reaction liquid space velocity is 4.87h -1 . The condensation intermediate is reacted with hydrogen in countercurrent in the two-stage Raney nickel reaction tower in series. The hydrogen is collected from the top of the first fixed bed Raney nickel reaction tower 8-1, compressed by the hydrogen compressor 9, and then used in the second fixed bed Raney nickel reaction tower 8-2. A supplementary hydrogen pipeline is arranged at the tower bottom of the second fixed bed Raney nickel reaction tower 8-2, and the hydrogen pressure at the top of the first fixed bed Raney nickel reaction tower 8-1 is automatically controlled at 1MPaA. The saturated long-chain alkane intermediate product is collected from the tower bottom of the second fixed bed Raney nickel reaction tower, and the collection rate is 69.55kg / h. The detection shows that the yield of the saturated long-chain alkane intermediate product is 72.1%. The two-stage reaction tower is provided with a jacket outside, steam is introduced into the jacket for heating, and the operating temperature is 100℃ for the first fixed bed Raney nickel reaction tower and 150℃ for the second fixed bed Raney nickel reaction tower.

[0077] Example 5

[0078] (5) The hydroxy aldehyde condensation reaction process is the same as that of Example 1.

[0079] (6) The solid condensate preparation process is the same as that of Example 1.

[0080] (7) The condensate solution preparation process is the same as that of Example 1.

[0081] (8) The condensation intermediate solution prepared in step (3) is delivered by the dissolving liquid delivery pump 7 to the first fixed bed Raney nickel reaction tower 8-1 (fixed bed Raney nickel reaction tower 8-1, 8-2 specifications: Ф150mm x 1200mm; material: 316L; catalyst filling amount: Raney nickel catalyst 18L) at a rate of 68.89kg / h. The fixed bed Raney nickel reaction tower 8-1, 8-2 is provided with two fixed bed layers, and a liquid redistributor is arranged between the fixed bed layers. The reaction liquid space velocity is 4.87h -1. The condensation intermediate reacts with hydrogen in a countercurrent manner in a two-stage Raney nickel reaction tower connected in series. The hydrogen is extracted from the top of the first-stage fixed-bed Raney nickel reaction tower 8-1, compressed by the hydrogen compressor 9, and then reused in the second-stage fixed-bed Raney nickel reaction tower 8-2. A hydrogen supplement pipeline is provided at the kettle of the second-stage fixed-bed Raney nickel reaction tower 8-2, which automatically controls the hydrogen pressure at the top of the first-stage fixed-bed Raney nickel reaction tower 8-1 to 1.5 MPaA. The saturated long-chain alkane intermediate product is extracted from the kettle of the second-stage fixed-bed Raney nickel reaction tower at a extraction rate of 69.75 kg / h. The yield of the saturated long-chain alkane intermediate product is detected to be 94.1%. The outside of the two-stage reaction tower is provided with a jacket, and steam is introduced into the jacket for heating. The operating temperature is 120°C for the first-stage fixed-bed Raney nickel reaction tower and 170°C for the second-stage fixed-bed Raney nickel reaction tower.

[0082] Example 6

[0083] (9) The aldol condensation reaction process is the same as in Example 1.

[0084] (10) The preparation process of the solid condensate is the same as that of Example 1.

[0085] (11) The preparation process of the condensate solution is the same as that in Example 1.

[0086] The condensation intermediate solution prepared in step (3) is delivered to a fixed-bed Raney nickel reaction tower 8-1 at a rate of 68.89 kg / h by a dissolving liquid delivery pump 7 (specifications of fixed-bed Raney nickel reaction towers 8-1 and 8-2: Ø150 mm × 1200 mm; material: 316L; catalyst filling amount: Raney nickel catalyst 18L). Both fixed-bed Raney nickel reaction towers 8-1 and 8-2 are equipped with two fixed bed layers, with a liquid redistributor between the fixed bed layers. The reaction liquid space velocity is 5h -1 . The condensation intermediate reacts with hydrogen in a countercurrent manner in a two-stage Raney nickel reaction tower connected in series. The hydrogen is extracted from the top of the first-stage fixed-bed Raney nickel reaction tower 8-1, compressed by the hydrogen compressor 9, and then reused in the second-stage fixed-bed Raney nickel reaction tower 8-2. A hydrogen supplement pipeline is provided at the kettle of the second-stage fixed-bed Raney nickel reaction tower 8-2, which automatically controls the hydrogen pressure at the top of the first-stage fixed-bed Raney nickel reaction tower 8-1 to 1.5 MPaA. The saturated long-chain alkane intermediate product is extracted from the kettle of the second-stage fixed-bed Raney nickel reaction tower at a extraction rate of 69.67 kg / h. The yield of the saturated long-chain alkane intermediate product is detected to be 85.6%. The outside of the two-stage reaction tower is provided with a jacket, and steam is introduced into the jacket for heating. The operating temperature is 110°C for the first-stage fixed-bed Raney nickel reaction tower and 160°C for the second-stage fixed-bed Raney nickel reaction tower.

[0087] From the product yields of Examples 1-6, it can be seen that:

[0088] 1. The condensation conversion rate in the tubular reaction increases with the extension of the residence time. A residence time of 1.5 h can achieve a maximum condensation yield of 95.4%;

[0089] 2. As the reaction temperature increases, the yield of the condensation product decreases;

[0090] 3. The space velocity of the reaction liquid after hydrogenation of the condensation intermediate (4~5h -1 Within the range) has little effect on the yield of hydrogenation products;

[0091] 4. The reaction temperature has a great influence on the hydrogenation saturation of the condensation intermediates. The reaction temperature of the first-stage reaction tower needs to be above 120°C, and the reaction temperature of the second-stage reaction tower needs to be above 170°C.

[0092] 5. Increasing the reaction pressure of the hydrogenation saturation reaction of the condensation intermediate is helpful to improve the reaction yield. A satisfactory reaction yield can be obtained when the reaction pressure is 1.5 MPaA.

[0093] Throughout this specification, references to terms such as "one embodiment," "example," or "specific example" indicate that the specific features, structures, materials, or characteristics described in conjunction with that embodiment or example are included in at least one embodiment or example of the present invention. In this specification, schematic representations of these terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

[0094] The basic principles, main features, and advantages of the present invention are shown and described above. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions are merely illustrative of the principles of the present invention. Various changes and modifications may be made to the present invention without departing from the spirit and scope of the present invention, and such changes and modifications fall within the scope of the invention as claimed.

Claims

1. A continuous production method for preparing long-chain alkane intermediates from bio-based platform compounds, characterized in that: The following steps are involved: In an aqueous phase, under the catalysis of an alkaline catalyst, a biomass-based furfural derivative and a biomass-based levulinic acid and its derivatives undergo an aldol condensation reaction to obtain a condensation liquid; The condensation liquid is acidified with a sulfuric acid aqueous solution, and the condensation intermediate is precipitated from the aqueous solution, and then the condensation intermediate solid and mother liquor are obtained by solid-liquid separation, and the mother liquor is used to return to prepare the sulfuric acid aqueous solution; the condensation intermediate solid is then dried and dehydrated; The dried and dehydrated condensation intermediate solid is dissolved in a solvent to obtain a condensation intermediate solution; The condensation intermediate solution is passed through two fixed-bed Raney nickel reaction towers connected in series, and reacts with hydrogen under the action of Raney nickel catalyst to obtain a saturated long-chain alkane intermediate solution.

2. The continuous production method for preparing long-chain alkane intermediates from bio-based platform compounds according to claim 1, characterized in that: The biomass-based furfural derivatives include: furfural-based compounds obtained by dehydration and hydrolysis of hemicellulose and cellulose; The biomass-based levulinic acid is levulinic acid prepared by acid-catalyzed hydrolysis of cellulose as a raw material; the derivative of the biomass-based levulinic acid is levulinic acid ester; The alkaline catalyst is NaOH or KOH.

3. The continuous production method for preparing long-chain alkane intermediates from bio-based platform compounds according to claim 2, characterized in that: The concentration of the biomass-based furfural derivative is 60wt% to 90wt%, and the concentration of the alkaline catalyst is 2wt% to 10wt%. The molar ratio of the biomass-based furfural derivative to biomass-based levulinic acid and its derivatives is 1 to 2:

1.

4. The continuous production method for preparing long-chain alkane intermediates from bio-based platform compounds according to claim 1, characterized in that: Static mixing internal components and tube wall flow-disturbing internal components are arranged in the tubular reactor.

5. The continuous production method for preparing long-chain alkane intermediates from bio-based platform compounds according to claim 1, characterized in that: The condensation liquid is acidified with 8 wt % sulfuric acid aqueous solution; the pH of the condensation liquid after acidification is 3-5.

6. The continuous production method for preparing long-chain alkane intermediates from bio-based platform compounds according to claim 1, characterized in that: The solvent is methanol, ethanol or tetrahydrofuran, and the concentration of the condensation intermediate in the condensation intermediate solution is 0.5 wt % to 50 wt %.

7. The continuous production method for preparing long-chain alkane intermediates from bio-based platform compounds according to claim 1, characterized in that: The fixed-bed Raney nickel reaction tower is provided with two-stage fixed bed layers for loading Raney nickel catalyst, and a liquid redistributor is arranged between the fixed bed layers.

8. The continuous production method for preparing long-chain alkane intermediates from bio-based platform compounds according to claim 1, characterized in that: The Ni content in the Raney nickel catalyst is 25-35 wt%.

9. The continuous production method for preparing long-chain alkane intermediates from bio-based platform compounds according to claim 1, characterized in that: In the fixed-bed Raney nickel reaction tower, hydrogen is fed from the bottom of the tower to maintain the hydrogen pressure in the tower at 0.5-3 MPaA; hydrogen is extracted from the top of the first-stage fixed-bed Raney nickel reaction tower, compressed by a hydrogen compressor, and then sent to the second-stage fixed-bed Raney nickel reaction tower for reuse.

10. The continuous production method for preparing long-chain alkane intermediates from bio-based platform compounds according to claim 9, characterized in that: The fixed bed Raney nickel reaction tower is heated by an outer jacket or an inner coil, the temperature of the first fixed bed Raney nickel reaction tower is 100-140°C, and the temperature of the second fixed bed Raney nickel reaction tower is 140-180°C.

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