A Schizothrix algin and a method for producing hydrocarbons and oil using the same

Abstract

The present invention belongs to the technical fields of ecological restoration of water bodies and development of biomass energy, and particularly relates to a schizothrix algin and a method for producing hydrocarbon and oil by using the same. The novel schizothrix algin in the present invention has high fat content, high hydrogen index and low nitrogen and oxygen contents. The content of fatty carbon is 79.2%, and the contents of nitrogen and oxygen are 2.34% and 10.9% respectively, which are significantly lower than those of its original sample (6.27% and 38.1% respectively), and it has a high oil yield (58%) and hydrocarbon generation potential (64%).

Description

Technical Field

[0001] The invention belongs to the technical field of ecological restoration of water bodies and development of biomass energy, and particularly relates to a phycocyanin of Schizostigma fasciatum and a method for producing hydrocarbons and oil by utilizing the phycocyanin. Background Art

[0002] With the rapid development of economy, fossil fuels are being exploited and utilized in large quantities worldwide, and fossil energy is being exhausted. At the same time, greenhouse gases, harmful gases and heavy metals are emitted in large quantities, which leads to a series of related energy, ecological environment and human health problems. Global changes and human activities also lead to the outbreak of algae such as cyanobacteria in water bodies, causing algal blooms and red tides. Therefore, it is very urgent and urgent to find alternative resources for fossil fuels. Cyanobacteria (cyanobacteria) are the oldest photosynthetic bacteria on earth, but there is still a lack of systematic research on whether they can fix carbon and generate hydrocarbons; only a few studies at home and abroad have shown that only a few cyanobacteria can be isolated from algae. In recent years, biomass energy, as a green and environmentally friendly renewable energy, has been highly expected in solving the energy crisis. So, can we develop algae biomass such as cyanobacteria to achieve the restoration of water pollution and convert them into biomass resources? Reduce dependence on fossil energy?

[0003] Green algae are regarded as a new generation of biodiesel raw materials that can even completely replace fossil fuels due to their high photosynthesis efficiency, high oil content, short growth cycle, and high oil yield per unit area. Of course, corresponding technical means have also been developed one after another. In fact, as early as the 1990s, there were literature records on the related research of using hydrothermal liquefaction to treat Botryococcus braunii to produce biofuels. In addition, pyrolysis is also a technical means that can effectively convert biomass into bio-oil and hydrocarbon gases. However, these technologies can only convert biomass into biofuels and cannot accurately evaluate the oil and hydrocarbon production potential of biomass. In addition, there are also some problems in the energy application of green algae, such as it is difficult to select strains with fast growth and high oil content, and in most studies, researchers do not perform any treatment on green algae and directly produce biodiesel. However, due to the large amount of lipids, proteins, and polysaccharides in green algae and other algae, they are easily decomposed by heat during pyrolysis, resulting in high oxygen and nitrogen content and high acidity index in biodiesel, thus reducing the quality of biodiesel; in addition, the cost of artificially cultivating algal biomass is too high. Therefore, it is particularly important to remove proteins and polysaccharides from different algae. In 1998, Allard et al. reported a separation method that can effectively remove lipids, proteins, and polysaccharides from algae to obtain a type of algae-derived refractory organic matter with low nitrogen and oxygen content, namely algin. In fact, this algin is a highly fatty, non-hydrolyzable, and insoluble biopolymer, mainly present in the cell walls of some green algae, Stigonema, and flagellates. Only a few studies have reported the existence of this refractory organic matter in cyanobacteria. One of them was in 1988, when Chalansonnet et al. reported its existence in Schizothrix, but in subsequent studies, it was found that the separation method used by Chalansonnet et al. resulted in the algin isolated from Schizothrix containing some artificially synthesized substances. In addition, Biller et al. isolated a biomacromolecule similar to algin from Gloeobacter violaceus in 2015 and pyrolyzed it, and found that there were differences in the pyrolysis products of this biomolecule and those of green algal algin, such as the absence of some n-alkanes. However, there are few reports on the research of this type of cyanobacteria-derived biomacromolecule (algin) in the production of biodiesel as a third-generation biomass energy raw material. In this invention, we successfully isolated a new type of algin organic matter from pure-cultured cyanobacteria (Schizothrix), and used advanced solid-state 13 CNMR technology, Rock-Eval pyrolysis technology, and a gold tube-high-pressure autoclave closed pyrolysis system to perform structural characterization and pyrolysis experiments on the original sample of Schizothrix and the new type of algin organic matter isolated from it, and compared the structures and hydrocarbon generation capabilities of different organic matters in Schizothrix. Summary of the Invention

[0004] To overcome the disadvantages and deficiencies of the above-mentioned prior art, the primary object of the present invention is to provide a schizothrix phycocolloid.

[0005] Another object of the present invention is to provide a method for preparing the above-mentioned schizothrix phycocolloid.

[0006] Still another object of the present invention is to provide a method for producing hydrocarbons and oil using the above-mentioned schizothrix phycocolloid.

[0007] The object of the present invention is achieved by the following solutions:

[0008] A schizothrix phycocolloid, the molecular formula of the basic structural unit contained therein is C 32 H 58 O3.

[0009] Preferably, the content of fatty carbon in the schizothrix phycocolloid is 55.0% - 79.9%, and the contents of nitrogen and oxygen are 1.73% - 6.27% and 5.20% - 15.7% respectively. More preferably, the content of fatty carbon in the schizothrix phycocolloid is 79.2%, and the contents of nitrogen and oxygen are 2.34% and 10.9% respectively.

[0010] A method for preparing the above-mentioned schizothrix phycocolloid, comprising the following steps:

[0011] Mix schizothrix with dichloromethane and methanol for Soxhlet extraction, mix the obtained solid with trifluoroacetic acid (TFA), heat it at 90 - 130 °C in a protective atmosphere, hydrolyze the obtained solid precipitate at 60 - 100 °C under alkaline conditions, after the hydrolysis is completed, mix the precipitate with an acidic solution and heat it at 90 - 130 °C in a protective atmosphere, and obtain schizothrix phycocolloid after the reaction is completed.

[0012] The volume ratio of the dichloromethane to the methanol is 80 - 100:4 - 10, preferably 93:7.

[0013] The temperature of the Soxhlet extraction is 40 - 55 °C, preferably 46.5 °C, and the time is 12 - 72 h.

[0014] Preferably, the step of mixing the obtained solid with trifluoroacetic acid (TFA) and heating it at 90 - 130 °C in a protective atmosphere specifically is: (1) mix the solid with 1 - 4 M trifluoroacetic acid and heat it at 90 - 130 °C for 0.5 - 5 h; (2) mix the obtained precipitate with 3 - 8 M trifluoroacetic acid and heat it at 90 - 130 °C for 30 - 48 h.

[0015] More preferably, step (1) is repeated 2 - 4 times;

[0016] More preferably, the heating temperature in step (1) is 100 - 110 °C, and the heating time is 3 - 5 h.

[0017] More preferably, in step (2), the precipitate is successively mixed with trifluoroacetic acid at 2-4M and 4-6M, and after each mixing, it is heated at 100-110°C for 15-24h.

[0018] More preferably, after step (2) is completed, the product is washed with water until neutral.

[0019] The alkaline condition is composed of a methanol / water solution containing an alkali; the volume ratio of methanol to water is 80-90:10-20, preferably 85:15. The alkali is at least one of common alkalis such as sodium hydroxide and / or potassium hydroxide. The concentration of the alkali in the methanol / water solution is 0.5-3M.

[0020] The hydrolysis time is 0.5-5h, preferably 1h.

[0021] Preferably, after the hydrolysis reaction is completed, the obtained solid precipitate is washed with water until neutral.

[0022] The acidic solution is hydrochloric acid, and the concentration of the acidic solution is 4-8M, preferably 6M.

[0023] The heating reaction temperature for mixing the precipitate with the acidic solution is 100-120°C, and the heating reaction time is 12-36h. More preferably, the heating reaction temperature is 120°C and the heating reaction time is 24h.

[0024] The protective atmosphere in the present invention is nitrogen or a noble gas.

[0025] A method for producing hydrocarbons and oil using Schizothrix calciola algin, specifically, the obtained Schizothrix calciola algin is pyrolyzed at 40-60MPa to produce hydrocarbons and oil.

[0026] The pyrolysis temperature is 300-500°C, preferably 320-460°C, more preferably 450°C.

[0027] Preferably, the temperature increase condition for pyrolysis is to heat the temperature to 250°C within 8h, and then heat it to the target temperature at a rate of 15-20°C / h.

[0028] The present invention has the following advantages and beneficial effects compared with the prior art:

[0029] (1) The novel blue algae algin in the present invention has high fat content, high hydrogen index and low nitrogen and oxygen content. The content of fatty carbon is 79.2%, and the contents of nitrogen and oxygen are 2.34% and 10.9% respectively, which are significantly lower than those of its original sample (6.27% and 38.1% respectively).

[0030] (2) The novel blue algae algin in the present invention contains C6-C 32The n-alkane carbon chain has a maximum chain length of C 32 , and the main peak of the carbon chain is C 15 、C 17 、C 27 。

[0031] (3) The novel cyanobacterial algin in the present invention has a high oil production rate (58%) and hydrocarbon generation potential (64%). Brief Description of the Drawings

[0032] Figure 1 is the basic structural unit of the algin of Schizothrix.

[0033] Figure 2 is the NMR spectrum of the original sample of Schizothrix and its algin.

[0034] Figure 3 is a comparison chart of the oil production rate of the original sample of Schizothrix and its algin varying with temperature during the cracking process.

[0035] Figure 4 is a linear fitting chart of the hydrogen index of the algin of Schizothrix and different fractions of other algae with the oil production rate and hydrocarbon generation potential.

[0036] Figure 5 is the gas chromatogram of the light hydrocarbons and n-alkanes produced by the original sample of Schizothrix and its algin during the cracking process.

[0037] Figure 6 is a chart of the change in the n-alkane content produced by the original sample (a) of Schizothrix and its algin (b) with temperature during the cracking process.

[0038] Figure 7 is a comparison chart of the chromatograms and the corresponding n-alkane contents produced by the original sample of Schizothrix, algin, and kerogen at the optimal cracking temperature. Detailed Embodiments

[0039] The present invention will be further described in detail below in conjunction with embodiments, but the embodiments of the present invention are not limited thereto.

[0040] Reagents used in the embodiments can be conventionally purchased from the market without special instructions.

[0041] 1. Preparation of algin.

[0042] Prepare raw materials: original sample of algae, dichloromethane, methanol, trifluoroacetic acid, HCl, deionized water.

[0043] (1) Isolation of alginic acid: A certain amount of the original sample of Schizothrix (OS) was subjected to Soxhlet extraction with a mixed solution of dichloromethane and methanol (93:7) for 72 hours. The solid part (free lipid removed, LF) was dried overnight in an oven at 50 °C, and a part was saved. Take the LF fraction, add 2M trifluoroacetic acid (TFA), heat it at 100 °C under nitrogen protection for 3 hours, centrifuge to remove the supernatant, and obtain a solid precipitate. Repeat the above steps again. Then the obtained solid precipitate was mixed with 4M TFA and heated at 100 °C under nitrogen protection for 18 hours, and then the solid precipitate was mixed with 6M TFA and heated at 100 °C under nitrogen protection for 18 hours, and the supernatant was removed by centrifugation. The obtained solid precipitate was washed with ultrapure water until neutral, and then hydrolyzed with a methanol:water (85:15) (v / v) solution of 1M KOH at 80 °C for 1 hour. After the reaction, it was centrifuged at 4000 rpm, and the supernatant was discarded. The solid precipitate was washed with ultrapure water until neutral, and finally heated with 6M HCl at 110 °C under nitrogen protection for 24 hours, and the supernatant was removed by centrifugation. The solid precipitate (alginic acid, NHOM) was washed with ultrapure water until neutral, freeze-dried, and stored.

[0044] 2. Establishment of the basic molecular structural unit and molecular formula of alginic acid

[0045] The basic molecular structural unit of alginic acid was fitted using Chemsketch 12.0 (ACD / Labs 2016) software and gNMR software, and the molecular formula of the basic structural unit of alginic acid was determined.

[0046] 3. Pyrolysis in a gold tube - autoclave, and the specific experimental process is as follows:

[0047] (1) Pyrolysis process:

[0048] 50 - 100 mg of the alginic acid sample was sealed in a gold tube under argon protection. The gold tubes were placed in 10 autoclaves respectively and placed in the same pyrolysis furnace for pyrolysis reaction. During the pyrolysis process, a constant pressure of 50 MPa was maintained. The autoclaves were placed in an electric furnace controlled by programmed temperature. Set 10 temperature points (320, 340, 360, 380, 400, 410, 420, 430, 450, 460 °C). One gold tube was used for each sample at each temperature point. The pyrolysis temperature increase program was: rapidly heat the autoclave from room temperature to 250 °C within 8 hours, and then heat it to the target temperature at a heating rate of 20 °C / h respectively. Immediately close the pressure control valve corresponding to the autoclave, take the autoclave out of the electric furnace, immediately cool it in a water bath, and take out the pyrolyzed gold tube from the autoclave for the next experimental analysis. Take it out after rising from room temperature to the target temperature and wait for sample injection analysis.

[0049] (2) Analysis of gaseous hydrocarbon components:

[0050] The collection of gaseous hydrocarbon components is completed in a vacuum glass system. A gold tube with a washed surface is placed in a vacuum system of a fixed volume, pierced with a needle under vacuum conditions. After the pyrolysis gas products are completely released from the gold tube, the connection channel between the vacuum system and the Agilent 6890N gas chromatograph (GC) instrument is opened for gas composition analysis, and the external standard method is used for quantification.

[0051] (3) Analysis of light hydrocarbon components:

[0052] For the gold tube pierced under vacuum conditions, its volatile hydrocarbon components are collected in a 4 mL glass bottle. After complete volatilization, it is cooled with liquid nitrogen, and immediately 3 mL of n-pentane is added. After the gold tube is taken out, it is cut open with scissors and placed in the above-mentioned 4 mL glass bottle, and a standard sample is added for injection analysis.

[0053] (4) C 14+ Component analysis:

[0054] After the analysis of light hydrocarbon components, the n-pentane in the 4 mL glass bottle is volatilized to dryness, and the residue in the bottle is taken out and extracted with dichloromethane: methanol (93:7, v / v) in a Soxhlet extractor for 72 h. After extraction, the solvent is rotary evaporated to dryness and weighed. The extract is separated into saturates, aromatics and resins by a silica gel chromatographic column. These three parts are dried and weighed. The insoluble residue is recovered from the filter paper, dried and weighed.

[0055] Parameter comparison

[0056] The elemental analysis results and Rock-Eval parameters of the Scytosiphon algin in the present invention are compared with other fractions isolated from Scytosiphon and some kerogens and listed in Table 1. In addition, other parameters of the novel cyanobacterial algin (content of aliphatic hydrocarbons, hydrogen index, oil production rate, hydrocarbon generation potential and main carbon chain peak of n-alkanes contained) are compared with some cyanobacteria, cyanobacteria-derived algal mixtures and green algae studied by predecessors, and the comparison results are listed in Table 2.

[0057] Table 1. Comparison table of elemental analysis and Rock-Eval parameters

[0058]

[0059] Table 2. Comparison of Scytosiphon algin with other cyanobacteria, cyanobacteria-derived algal mixtures and green algae.

[0060]

[0061] The hydrogen index of the algin of Scytosiphon is 811 mg HC / g TOC, which is significantly higher than the hydrogen index of its original sample and the algin isolated from other algal species, and significantly higher than the hydrogen index of Maoming kerogen.

[0062] From Figure 2 it can be seen that the NMR spectrum of the phycobilin of the said Schizothrix is different from that of the phycobilin of green algae. Compared with the phycobilin of green algae, the novel cyanobacteria phycobilin in the present invention contains additional functional groups. This is due to the difference in the inherent composition structures of the two types of phycobilins.

[0063] The NMR spectrum of the phycobilin of Schizothrix and the NMR spectrum of the cyanobacteria phycobilin Figure 1 are similar. However, the composition of the n-alkanes is different. The maximum chain length of the n-alkanes in a cyanobacteria phycobilin reported in the literature is C 29 , and it lacks C 27 and C 28 , while the carbon chain of the phycobilin in the present invention is C6-C 32 , and the main peak of the carbon chain is C 15 , C 17 , C 27 .

[0064] The above embodiments are the preferred embodiments of the present invention, but the embodiments of the present invention are not limited by the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications made without departing from the spirit and principle of the present invention shall be equivalent substitution methods and are all included in the protection scope of the present invention.

Claims

1. A Schizothrix algin, characterized in that: The molecular formula of the basic structural unit contained in the schizothrix alga lignin is C 32 H 58 O3, and its structural formula is shown as follows:

2. The schizothrix phycobilin according to claim 1, characterized in that: The content of fatty carbon in the schizothrix algin is 55.0% - 79.9%, and the contents of nitrogen and oxygen are 1.73% - 6.27% and 5.20% - 15.7% respectively.

3. A method for preparing the schizothrix algin described in claim 1 or 2, characterized in that It includes the following steps: Mix schizothrix with dichloromethane and methanol for Soxhlet extraction, mix the obtained solid with trifluoroacetic acid, and heat it at 90 - 130 °C in a protective atmosphere. Hydrolyze the solid precipitate obtained from the reaction at 60 - 100 °C under alkaline conditions. After the hydrolysis is completed, mix the precipitate with an acidic solution and heat it at 90 - 130 °C in a protective atmosphere. After the reaction is completed, schizothrix algin is obtained.

4. The method according to claim 3, characterized in that: The volume ratio of the dichloromethane to the methanol is 80 - 100:4 - 10; the temperature of the Soxhlet extraction is 40 - 55 °C, and the time is 12 - 72 h.

5. The method according to claim 3, characterized in that: The specific operation of mixing the obtained solid with trifluoroacetic acid and heating it at 90 - 130 °C in a protective atmosphere is as follows: (1) Mix the solid with 1 - 4 M trifluoroacetic acid and heat it at 90 - 130 °C for 0.5 - 5 h; (2) Mix the obtained precipitate with 3 - 8 M trifluoroacetic acid and heat it at 90 - 130 °C for 30 - 48 h.

6. According to the method described in claim 5, it is characterized in that: The heating temperature in step (1) is 100 - 110 °C, and the heating time is 3 - 5 h; Step (1) is repeated 2 - 4 times; In step (2), the precipitate is successively mixed with 4 M and 4 - 6 M trifluoroacetic acid, and after each mixing, it is heated at 100 - 110 °C for 15 - 24 h.

7. According to the method described in claim 5, it is characterized in that: The alkaline condition is composed of an alkali-containing methanol / water solution; the volume ratio of the methanol to the water is 80 - 90:10 - 20; the alkali is at least one of sodium hydroxide and / or potassium hydroxide; the concentration of the alkali in the methanol / water solution is 0.5 - 3 M.

8. According to the method described in claim 3, it is characterized in that: The acidic solution is hydrochloric acid, and the concentration of the acidic solution is 4 - 8 M; The heating reaction temperature after mixing the precipitate with the acidic solution is 100 - 120 °C, and the heating reaction time is 12 - 36 h.

9. A method for producing hydrocarbons and oil using the schizothrix algin described in claim 1 or 2, characterized in that: Specifically, the obtained schizothrix algin is pyrolyzed at 40 - 60 MPa to produce hydrocarbons and oil.

10. The method according to claim 9, wherein: The temperature of the pyrolysis is 300 - 500 °C.

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