A method for producing natural gas from biomass and polyols

Abstract

The application relates to a method for preparing natural gas by taking biomass and polyhydroxy compounds as raw materials. The method comprises the following steps: mixing the raw materials with water and a catalyst, and carrying out a reduction reaction in a reducing atmosphere to obtain a product containing natural gas; the raw materials are selected from biomass raw materials or / and polyhydroxy compounds; the biomass raw materials are selected from at least one of beech sawdust, poplar sawdust, pine sawdust, birch sawdust, wheat straw or corn straw; the polyhydroxy compounds are selected from at least one of cellulose, hemicellulose, cellobiose, xylose, guaiacol, sorbitol, isosorbide, glycerol, erythritol, xylitol or glucose; the catalyst comprises a carrier and an active component loaded on the surface of the carrier; the active component is selected from metal elements; the metal elements are selected from at least one of the single elements of ruthenium, rhodium, platinum, palladium or iridium. The method provides a path for converting biomass such as sawdust and polyhydroxy compounds to prepare natural gas, and has important industrial application prospects.

Description

Technical Field

[0001] This application relates to the fields of chemical engineering or polymer science, specifically to a method for preparing natural gas, applicable to the reaction process of preparing natural gas from biomass such as wood chips and polyhydroxy compounds through carbon-oxygen and carbon-carbon bond breaking strategies. Background Technology

[0002] Biofuels are among the most important renewable energy sources, produced directly or indirectly from biomass. Biomass feedstocks have attracted widespread attention from researchers due to their abundant sources and renewable properties. In 2016, biofuels provided approximately 10% of total primary energy supply; therefore, researching and developing renewable biomass energy is of great significance for sustainable social development. Catalytic biomass conversion to produce biofuels and chemicals has a profound impact on alleviating the global energy crisis and global environmental problems. Lignocellulose, as an abundant renewable biomass resource, has been recognized as a promising sustainable source for producing biofuels and chemicals. Lignocellulose in plant cell walls is a biopolymer, mainly composed of cellulose (35-50 wt%), hemicellulose (20-35 wt%), and lignin (10-25 wt%). Due to the structural heterogeneity and complexity of cell wall components, innovative methods for utilizing lignocellulose biomass have attracted widespread attention.

[0003] Currently, research on biomass-to-natural-gas conversion mainly focuses on the following technologies: fermentation, pyrolysis gasification, and catalytic hydrothermal conversion. Fermentation is considered one of the most promising methods for converting lignocellulosic materials into bioenergy. This method offers advantages such as mild reaction conditions, a wide range of raw material sources, and low production costs. However, it suffers from long reaction cycles, low efficiency, and high CO2 emissions (25-50%) during fermentation. Many researchers have attempted to use biomass pyrolysis gasification to produce natural gas, but its reaction temperatures are generally high, and the CH4 content in the gaseous products is low. Furthermore, pyrolysis gasification generates large amounts of tar and coke. Therefore, more and more researchers are focusing on hydrothermal catalytic conversion, which offers milder reaction conditions. Biomass hydrothermal catalytic conversion to natural gas is typically carried out at or near supercritical water conditions (374℃, 22MPa). Compared to pyrolysis gasification, which has higher reaction temperatures (>500℃), this method is more conducive to the generation of CH4-rich gas. However, existing methods generally suffer from low efficiency and demanding conditions, necessitating the development of new conversion technologies to reduce reaction conditions and improve product selectivity. Summary of the Invention

[0004] The purpose of this application is to provide a new route for producing natural gas using biomass and polyhydroxy compounds through carbon-oxygen and carbon-carbon bond breaking strategies.

[0005] According to one aspect of this application, a method for preparing natural gas is provided, comprising at least the following steps: mixing raw materials with water and a catalyst, and conducting a reduction reaction in a reducing atmosphere to obtain a product containing natural gas;

[0006] The raw materials are selected from biomass raw materials and / or polyhydroxy compounds;

[0007] The biomass raw material is selected from at least one of beech wood chips, poplar wood chips, pine wood chips, birch wood chips, wheat straw, or corn straw;

[0008] The polyhydroxy compound is selected from at least one of cellulose, hemicellulose, cellulose diol, xylose, guaiacol, sorbitol, isosorbide, glycerol, erythritol, xylitol or glucose;

[0009] The catalyst includes a support and an active component supported on the surface of the support;

[0010] The active component is selected from metal elements; the metal element is selected from at least one of ruthenium, rhodium, platinum, palladium or iridium.

[0011] The mass of the raw material is 1 to 25% of the mass of water;

[0012] Optionally, the mass of the raw material is 1 to 15% of the mass of water;

[0013] Optionally, the mass of the raw material is 2 to 10% of the mass of water.

[0014] The support in the catalyst is selected from mesoporous silica or mesoporous titanium dioxide;

[0015] The mesopore size of the carrier is 2–4 nm;

[0016] The content of the active component in the catalyst is 5-10 wt%.

[0017] The catalyst is pretreated;

[0018] The pretreatment process involves reduction in a reducing gas at 200–350°C for 3–6 hours.

[0019] The reducing gas is selected from a hydrogen atmosphere.

[0020] The mass of the catalyst is 5-60% of the mass of the raw material;

[0021] Optionally, the mass of the catalyst is 10-50% of the mass of the biomass feedstock.

[0022] The reduction reaction is carried out under closed conditions.

[0023] The temperature of the reduction reaction is 120–350°C;

[0024] Optionally, the temperature of the reduction reaction is 180–350°C;

[0025] Optionally, the temperature of the reduction reaction is 210–350°C.

[0026] The reduction reaction takes 0.5 to 24 hours.

[0027] Optionally, the reduction reaction takes 2 to 15 hours;

[0028] Optionally, the reduction reaction takes 2 to 10 hours.

[0029] The reducing atmosphere is a hydrogen atmosphere;

[0030] The reaction pressure is 0.1–8 MPa;

[0031] Optionally, the reaction pressure is 1–6 MPa;

[0032] Optionally, the reaction pressure is 3 to 6 MPa.

[0033] When the raw material is biomass, the natural gas yield is 43-63%.

[0034] When the feedstock is a polyhydroxy compound, the natural gas yield is 70-94%.

[0035] Specifically, the method includes at least the following steps:

[0036] (1) Preparation of mesoporous silica (MSN);

[0037] (2) Metal loading on mesoporous silica (MSN);

[0038] (3) Mix biomass such as wood chips and production raw materials such as polyhydroxy compounds with water and catalyst, and react them in a closed pressure vessel with a reducing atmosphere.

[0039] In step (3), the volume of water is 10-65% of the total volume of the pressure vessel;

[0040] Optionally, the volume of the water is 20% to 50% of the total volume of the pressure vessel;

[0041] Alternatively, the volume of water is 30 to 45% of the total volume of the pressure vessel.

[0042] Low temperatures can lead to low substrate conversion rates, while increasing the reaction temperature can cause side reactions. Within a certain time range, the conversion rate increases with increasing reaction time, but after a certain period of time, the conversion rate and product selectivity tend to stabilize.

[0043] The reaction is carried out in a high-pressure reactor, sealed at room temperature and normal atmospheric pressure. The reaction atmosphere is replaced by argon, nitrogen, or hydrogen. During the reaction, the pressure inside the reactor includes the solvent pressure and the high pressure generated by the thermal expansion of hydrogen.

[0044] The advantages of this application are:

[0045] This paper discloses for the first time a novel pathway for the production of natural gas under relatively mild conditions using biomass such as sawdust and polyhydroxy compounds via carbon-oxygen and carbon-carbon bond breaking strategies. This pathway, through C / C and CO bond breaking strategies, opens up new applications for the catalytic conversion of biomass and polyhydroxy compounds, and provides a new method for synthesizing natural gas with significant application value. Detailed Implementation

[0046] The present application is described in detail below with reference to the embodiments, but the present application is not limited to these embodiments.

[0047] Unless otherwise specified, the raw materials and catalysts used in the embodiments of this application were all purchased commercially.

[0048] The analysis method in the embodiments of this application is as follows:

[0049] Gas products were analyzed using gas chromatographs (Agilent 7890A and Agilent 7890B) equipped with thermal conductivity detectors (TCD) and flame ionization detectors (FID).

[0050] The yield calculation in the embodiments of this application is as follows:

[0051]

[0052] The MSN used in the embodiments was prepared by the method described in reference [1] Lu, F.; Wu, SH; Hung, Y.; Mou, CY. Size Effect on Cell Uptake in Well-suspended, Uniform Mesoporous SilicaNanoparticles. Small 2009, 5, 1408-1413.

[0053] Example 1

[0054] Catalyst pretreatment: 0.18 g Ru / SiO2 was reduced at 200 °C under a hydrogen atmosphere for 3 h. In a reactor, 1 g isosorbide, 0.15 g Ru / SiO2, and 20 mL of water were added. The reactor was purged with nitrogen, then with hydrogen, and purged to a pressure of 4 MPa. The reaction was carried out at 210 °C for 2 h. After the reaction, the mixture was cooled to room temperature, and qualitative and quantitative analyses were performed by gas chromatography. The retention times of the products were consistent with those of the standards. The natural gas yield was 41%.

[0055] Example 2

[0056] Catalyst pretreatment: 0.18 g Ru / MSN was reduced at 200 °C under a hydrogen atmosphere for 3 h. In a reactor, 1 g isosorbide, 0.15 g Ru / MSN, and 20 mL of water were added. The reactor was purged with nitrogen, then with hydrogen, and the pressure was increased to 4 MPa. The reaction was carried out at 230 °C for 5 h. After the reaction, the temperature was lowered to room temperature, and qualitative and quantitative analyses were performed by gas chromatography. The retention times of the products were consistent with those of the standards. The natural gas yield was 84%.

[0057] Example 3

[0058] Catalyst pretreatment: 0.18 g Ru / MSN was reduced at 350 °C under a hydrogen atmosphere for 3 h. In a reactor, 1 g isosorbide, 0.15 g Ru / MSN, and 20 mL of water were added. The reactor was purged with nitrogen, then with hydrogen, and the pressure was increased to 4 MPa. The reaction was carried out at 210 °C for 2 h. After the reaction, the temperature was lowered to room temperature, and qualitative and quantitative analyses were performed by gas chromatography. The retention times of the products were consistent with those of the standards. The natural gas yield was 89%.

[0059] Example 4

[0060] Catalyst pretreatment: 0.18 g Ru / MSN was reduced at 350 °C under a hydrogen atmosphere for 3 h. In a reactor, 1 g isosorbide, 0.15 g Ru / MSN, and 20 mL of water were added. The reactor was purged with nitrogen, then with hydrogen, and the pressure was increased to 4 MPa. The reaction was carried out at 220 °C for 2 h. After the reaction, the temperature was lowered to room temperature, and qualitative and quantitative analyses were performed by gas chromatography. The retention times of the products were consistent with those of the standards. The natural gas yield was 91%.

[0061] Example 5

[0062] Catalyst pretreatment: 0.18 g Ru / MSN was reduced at 350 °C under a hydrogen atmosphere for 3 h. In a reactor, 1 g isosorbide, 0.15 g Ru / MSN, and 20 mL of water were added. The reactor was purged with nitrogen, then with hydrogen, and the pressure was increased to 4 MPa. The reaction was carried out at 230 °C for 2 h. After the reaction, the temperature was lowered to room temperature, and qualitative and quantitative analyses were performed by gas chromatography. The retention times of the products were consistent with those of the standards. The natural gas yield was 92%.

[0063] Example 6

[0064] Catalyst pretreatment: 0.18 g Ru / MSN was reduced at 350 °C under a hydrogen atmosphere for 3 h. In a reactor, 1 g isosorbide, 0.15 g Ru / MSN, and 20 mL of water were added. The reactor was purged with nitrogen, then with hydrogen, and the pressure was increased to 4 MPa. The reaction was carried out at 240 °C for 2 h. After the reaction, the temperature was lowered to room temperature, and qualitative and quantitative analyses were performed by gas chromatography. The retention times of the products were consistent with those of the standards. The natural gas yield was 94%.

[0065] Example 7

[0066] Catalyst pretreatment: 0.18 g Ru / MSN was reduced at 350 °C under a hydrogen atmosphere for 3 h. In a reactor, 1 g isosorbide, 0.15 g Ru / MSN, and 20 mL of water were added. The reactor was purged with nitrogen, then with hydrogen, and the pressure was increased to 4 MPa. The reaction was carried out at 250 °C for 2 h. After the reaction, the temperature was lowered to room temperature, and qualitative and quantitative analyses were performed by gas chromatography. The retention times of the products were consistent with those of the standards. The natural gas yield was 92%.

[0067] Example 8

[0068] Catalyst pretreatment: 0.18 g Ru / MSN was reduced at 350 °C under a hydrogen atmosphere for 3 h. In a reactor, 1 g glycerol, 0.15 g Ru / MSN, and 20 mL water were added, purged with nitrogen, then with hydrogen, and the pressure was increased to 4 MPa. The reaction was carried out at 250 °C for 5 h. After the reaction, the mixture was cooled to room temperature, and qualitative and quantitative analyses were performed by gas chromatography. The retention times of the products were consistent with those of the standards. The natural gas yield was 92%.

[0069] Example 9

[0070] Catalyst pretreatment: 0.18 g Ru / MSN was reduced at 350 °C under a hydrogen atmosphere for 3 h. In a reactor, 1 g erythritol, 0.15 g Ru / MSN, and 20 mL of water were added. The reactor was purged with nitrogen, then with hydrogen, and the pressure was increased to 4 MPa. The reaction was carried out at 250 °C for 5 h. After the reaction, the temperature was lowered to room temperature, and qualitative and quantitative analyses were performed by gas chromatography. The retention times of the products were consistent with those of the standards. The natural gas yield was 90%.

[0071] Example 10

[0072] Catalyst pretreatment: 0.18 g Ru / MSN was reduced at 350 °C under a hydrogen atmosphere for 3 h. In a reactor, 1 g xylitol, 0.15 g Ru / MSN, and 20 mL of water were added. The reactor was purged with nitrogen, then with hydrogen, and the pressure was increased to 4 MPa. The reaction was carried out at 250 °C for 5 h. After the reaction, the temperature was lowered to room temperature, and qualitative and quantitative analyses were performed by gas chromatography. The retention times of the products were consistent with those of the standards. The natural gas yield was 86%.

[0073] Example 11

[0074] Catalyst pretreatment: 0.18 g Ru / MSN was reduced at 350 °C under a hydrogen atmosphere for 3 h. In a reactor, 1 g xylose, 0.15 g Ru / MSN, and 20 mL of water were added. The reactor was purged with nitrogen, then with hydrogen, and the pressure was increased to 4 MPa. The reaction was carried out at 250 °C for 5 h. After the reaction, the temperature was lowered to room temperature, and qualitative and quantitative analyses were performed by gas chromatography. The retention times of the products were consistent with those of the standards. The natural gas yield was 93%.

[0075] Example 12

[0076] Catalyst pretreatment: 0.18 g Ru / MSN was reduced at 350 °C under a hydrogen atmosphere for 3 h. In a reactor, 1 g glucose, 0.15 g Ru / MSN, and 20 mL water were added. The reactor was purged with nitrogen, then with hydrogen, and the pressure was increased to 4 MPa. The reaction was carried out at 250 °C for 5 h. After the reaction, the mixture was cooled to room temperature, and qualitative and quantitative analyses were performed by gas chromatography. The retention times of the products were consistent with those of the standards. The natural gas yield was 88%.

[0077] Example 13

[0078] Catalyst pretreatment: 0.18 g Ru / MSN was reduced at 350 °C under a hydrogen atmosphere for 3 h. In a reactor, 1 g microcrystalline cellulose, 0.15 g Ru / MSN, and 20 mL of water were added. The reactor was purged with nitrogen, then with hydrogen, and the pressure was increased to 4 MPa. The reaction was carried out at 250 °C for 5 h. After the reaction, the temperature was lowered to room temperature, and qualitative and quantitative analyses were performed by gas chromatography. The retention times of the products were consistent with those of the standards. The natural gas yield was 83%.

[0079] Example 14

[0080] Catalyst pretreatment: 0.18 g Ru / MSN was reduced at 350 °C under a hydrogen atmosphere for 3 h. In a reactor, 1 g cellobiose, 0.15 g Ru / MSN, and 20 mL of water were added. The reactor was purged with nitrogen, then with hydrogen, and the pressure was increased to 4 MPa. The reaction was carried out at 250 °C for 5 h. After the reaction, the temperature was lowered to room temperature, and qualitative and quantitative analyses were performed by gas chromatography. The retention times of the products were consistent with those of the standards. The natural gas yield was 79%.

[0081] Example 15

[0082] Catalyst pretreatment: 0.18 g Ru / MSN was reduced at 350 °C under a hydrogen atmosphere for 3 h. In a reactor, 0.25 g beech wood chips, 0.15 g Ru / MSN, and 20 mL of water were added. The reactor was purged with nitrogen, then with hydrogen, and the pressure was increased to 4 MPa. The reaction was carried out at 250 °C for 5 h. After the reaction, the temperature was lowered to room temperature, and qualitative and quantitative analyses were performed by gas chromatography. The retention times of the products were consistent with those of the standards. The natural gas yield was 63%.

[0083] Example 16

[0084] Catalyst pretreatment: 0.18 g Ru / MSN was reduced at 350 °C under a hydrogen atmosphere for 3 h. In a reactor, 0.25 g poplar sawdust, 0.15 g Ru / MSN, and 20 mL of water were added. The reactor was purged with nitrogen, then with hydrogen, and the pressure was increased to 4 MPa. The reaction was carried out at 250 °C for 5 h. After the reaction, the temperature was lowered to room temperature, and qualitative and quantitative analyses were performed by gas chromatography. The retention times of the products were consistent with those of the standards. The natural gas yield was 61%.

[0085] Example 17

[0086] Catalyst pretreatment: 0.18 g Ru / MSN was reduced at 350 °C under a hydrogen atmosphere for 3 h. In a reactor, 0.25 g birch sawdust, 0.15 g Ru / MSN, and 20 mL of water were added. The reactor was purged with nitrogen, then with hydrogen, and the pressure was increased to 4 MPa. The reaction was carried out at 250 °C for 5 h. After the reaction, the temperature was lowered to room temperature, and qualitative and quantitative analyses were performed by gas chromatography. The retention time of the product was consistent with that of the standard. The natural gas yield was 53%.

[0087] Example 18

[0088] Catalyst pretreatment: 0.18 g Ru / MSN was reduced at 350 °C under a hydrogen atmosphere for 3 h. In a reactor, 0.25 g pine sawdust, 0.15 g Ru / MSN, and 20 mL of water were added. The reactor was purged with nitrogen, then with hydrogen, and the pressure was increased to 4 MPa. The reaction was carried out at 250 °C for 5 h. After the reaction, the temperature was lowered to room temperature, and qualitative and quantitative analyses were performed by gas chromatography. The retention time of the product was consistent with that of the standard. The natural gas yield was 50%.

[0089] Example 19

[0090] Catalyst pretreatment: 0.18 g Ru / MSN was reduced at 350 °C under a hydrogen atmosphere for 3 h. In a reactor, 1 g hemicellulose, 0.15 g Ru / MSN, and 20 mL of water were added. The reactor was purged with nitrogen, then with hydrogen, and the pressure was increased to 4 MPa. The reaction was carried out at 250 °C for 5 h. After the reaction, the temperature was lowered to room temperature, and qualitative and quantitative analyses were performed by gas chromatography. The retention times of the products were consistent with those of the standards. The natural gas yield was 85%.

[0091] Example 20

[0092] Catalyst pretreatment: 0.18 g Ru / MSN was reduced at 350 °C under a hydrogen atmosphere for 3 h. In a reactor, 0.25 g wheat straw, 0.15 g Ru / MSN, and 20 mL of water were added. The reactor was purged with nitrogen, then with hydrogen, and the pressure was increased to 4 MPa. The reaction was carried out at 250 °C for 5 h. After the reaction, the temperature was lowered to room temperature, and qualitative and quantitative analyses were performed by gas chromatography. The retention times of the products were consistent with those of the standards. The natural gas yield was 45%.

[0093] Example 21

[0094] Catalyst pretreatment: 0.18 g Ru / MSN was reduced at 350 °C under a hydrogen atmosphere for 3 h. In a reactor, 0.25 g corn stalks, 0.15 g Ru / MSN, and 20 mL of water were added. The reactor was purged with nitrogen, then with hydrogen, and the pressure was increased to 4 MPa. The reaction was carried out at 250 °C for 5 h. After the reaction, the temperature was lowered to room temperature, and qualitative and quantitative analyses were performed by gas chromatography. The retention times of the products were consistent with those of the standards. The natural gas yield was 43%.

[0095] Example 22

[0096] Catalyst pretreatment: 0.18 g Ru / MSN was reduced at 350 °C under a hydrogen atmosphere for 3 h. In a reactor, 0.25 g guaiacol, 0.15 g Ru / MSN, and 20 mL of water were added. The reactor was purged with nitrogen, then with hydrogen, and the pressure was increased to 4 MPa. The reaction was carried out at 250 °C for 5 h. After the reaction, the temperature was lowered to room temperature, and qualitative and quantitative analyses were performed by gas chromatography. The retention times of the products were consistent with those of the standards. The natural gas yield was 70%.

[0097] The above description is merely a few embodiments of this application and is not intended to limit this application in any way. Although this application discloses preferred embodiments as described above, it is not intended to limit this application. Any changes or modifications made by those skilled in the art without departing from the scope of the technical solution of this application using the disclosed technical content are equivalent to equivalent implementation cases and fall within the scope of the technical solution.

Claims

1. A method for preparing natural gas, characterized in that, It includes at least the following steps: mixing the raw materials with water and a catalyst, and carrying out a reduction reaction in a hydrogen atmosphere to obtain a product containing natural gas; The raw materials are selected from biomass raw materials and / or polyhydroxy compounds; The biomass raw material is selected from at least one of beech wood chips, poplar wood chips, pine wood chips, birch wood chips, wheat straw, or corn straw; The polyhydroxy compound is selected from at least one of cellulose, hemicellulose, cellulose diol, xylose, guaiacol, sorbitol, isosorbide, glycerol, erythritol, xylitol or glucose; The catalyst includes a support and an active component supported on the surface of the support; the support in the catalyst is selected from mesoporous silica or mesoporous titanium dioxide; the mesopore size of the support is 2~4 nm; The active component is selected from metallic elements; the metallic element is selected from at least one element selected from ruthenium, rhodium, platinum, palladium, or iridium. The catalyst is pretreated; the pretreatment process is reduction in a reducing gas at 200~350℃ for 3~6 h. The reduction reaction is carried out under closed conditions; The reduction reaction is carried out at a temperature of 120~350℃.

2. The preparation method according to claim 1, characterized in that, The mass of the raw material is 1 to 25% of the mass of water.

3. The preparation method according to claim 1, characterized in that, The mass of the raw material is 1 to 15% of the mass of water.

4. The preparation method according to claim 1, characterized in that, The mass of the raw material is 2 to 10% of the mass of water.

5. The preparation method according to claim 1, characterized in that, The active component in the catalyst is 5-10 wt%.

6. The preparation method according to claim 1, characterized in that, The mass of the catalyst is 5-60% of the mass of the raw material.

7. The preparation method according to claim 1, characterized in that, The mass of the catalyst is 10-50% of the mass of the biomass feedstock.

8. The preparation method according to claim 1, characterized in that, The reduction reaction is carried out at a temperature of 180~350℃.

9. The preparation method according to claim 1, characterized in that, The reduction reaction is carried out at a temperature of 210~350℃.

10. The preparation method according to claim 1, characterized in that, The reduction reaction takes 0.5 to 24 hours.

11. The preparation method according to claim 1, characterized in that, The reduction reaction takes 2 to 15 hours.

12. The preparation method according to claim 1, characterized in that, The reduction reaction takes 2 to 10 hours.

13. The preparation method according to claim 1, characterized in that, The reaction pressure is 0.1~8 MPa.

14. The preparation method according to claim 1, characterized in that, The reaction is carried out at a pressure of 1-6 MPa.

15. The preparation method according to claim 1, characterized in that, The reaction is carried out at a pressure of 3-6 MPa.

16. The preparation method according to claim 1, characterized in that, When the raw material is biomass, the natural gas yield is 43-63%. When the raw material is a polyhydroxy compound, the natural gas yield is 70-94%.

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