Production process for preparing pyridine-rich bio-oil through pretreatment biomass classification-nitrogen-rich pyrolysis

Abstract

The invention belongs to the technical field of biomass high-value utilization, and particularly relates to a production process for preparing pyridine-rich bio-oil through pretreatment biomass classification-nitrogen-rich pyrolysis. According to the production process for preparing the pyridine-rich bio-oil through pretreatment biomass classification-nitrogen-rich pyrolysis, classification-nitrogen-rich pyrolysis is that different pyrolysis reaction temperature intervals are set according to pyrolysis characteristics of three major components of biomass, and different pyrolysis steam with relatively enriched component contents is collected step by step. And converting the aldehyde-ketone-rich pyrolysis steam into pyridine-rich bio-oil under a nitrogen-rich pyrolysis condition. For pyrolysis steam with low content of aldehyde and ketone components, further online catalytic regulation is carried out to convert components which are easy to be subjected to aldehyde and ketonization into aldehyde and ketone substances, and then nitrogen-rich pyrolysis conversion is carried out. The pyrolysis steam which is not easy to generate aldehyde ketonization and is high in component content is used for preparing liquid fuel or other chemicals, and grading, quality-dividing and high-value utilization of all components of biomass is achieved.

Description

Technical Field

[0001] The invention belongs to the technical field of high-value utilization of biomass, and specifically relates to a production process for preparing pyridine-rich bio-oil by pre-treating biomass for classification and nitrogen-rich pyrolysis. Background Art

[0002] Nitrogen-containing compounds occupy an important position in fine chemicals, among which pyridine and its derivatives are one of the most common skeletons in drug molecules and agricultural chemicals, with huge annual demand. For example, pyridine pesticides are considered to be the fourth generation of pesticides, with advantages such as high efficiency, low toxicity, and good environmental compatibility. In addition, some pyridine derivatives have good fluorescence and have important applications in energy fields such as electroluminescent materials. However, at present, pyridine compounds in industry are mainly synthesized from fossil raw materials through multi-step reactions, which have prominent problems such as complex processes and large pollutant emissions. Studies have pointed out that compared with petroleum-based hydrocarbons, biomass as raw materials is easier to ammine to form nitrogen-containing chemicals. Therefore, it is of great significance to use pyrolysis of biomass raw materials to prepare high-value-added nitrogen-containing compounds such as pyridine.

[0003] There are many synthetic routes for pyridine compounds. For example, the main chemical synthesis methods for pyridine base (pyridine and its methyl substitutes) in industry include aldehyde (ketone)-ammonia method, acetylene-acetonitrile method and side chain alkylation method, among which aldehyde (ketone)-ammonia method is the main one at present. Most biomass in nature has low nitrogen content and cannot meet the conditions for the formation of large amounts of nitrogen-containing chemicals. Therefore, there are two main routes for preparing nitrogen-containing compounds such as pyridine by rapid pyrolysis: (1) Directedly obtain a single intermediate oxygen-containing substance, such as aldehydes, ketones, acetic acid, ethanol, etc., and then catalytically generate it in an ammonia atmosphere.

[0004] (2) The pyrolysis process directly introduces exogenous nitrogen (such as NH3, urea, etc., known as "nitrogen-rich pyrolysis") to catalyze the production of pyridine compounds.

[0005] Compared with route (1), route (2) does not require separation of intermediate products, reduces the high-energy consumption steps of bio-oil condensation-component purification-re-evaporation reaction, and converts multi-step reactions into one-step reactions, shortens the process route, and has the advantages of high atomic utilization. Studies have shown that small molecular aldehydes and ketones are important intermediates for the generation of pyridine compounds (CN202210149448.4); under high temperature conditions, weak acid catalysts and short residence time are easy to form pyridine compounds; nitrogen-containing compounds such as indole can also be converted into pyridine compounds under certain conditions. However, due to the activeness of aldehydes and ketones, condensation conversion is prone to occur during the purification process. Therefore, by regulating the biomass pyrolysis reaction process, the pyrolysis product components mainly composed of aldehydes and ketones can be generated in a targeted manner, and the yield of pyridine compounds and their enrichment in bio-oil can be significantly improved under nitrogen-rich pyrolysis conditions.

[0006] Agricultural and forestry biomass has the characteristics of being rich in oxygen and poor in nitrogen (oxygen content 30-50%, nitrogen content <0.5%). Although the introduction of exogenous nitrogen during pyrolysis can significantly increase the yield of nitrogen-containing compounds in bio-oil, the selectivity of pyridine compounds is still low (generally <10%). The main reasons are: (1) Traditional biomass pyrolysis is a single-stage pyrolysis, that is, the raw material is only pyrolyzed at a certain temperature, and the product precipitation temperature ranges of cellulose, hemicellulose and lignin in biomass overlap with each other, and there are certain differences in product composition. The bio-oil obtained during nitrogen-rich pyrolysis has many types of nitrogen-containing compounds and low content of pyridine products. The pyrolysis temperature ranges of the three components of biomass overlap with each other, and there are complex interactions between the pyrolysis products. For example, the main pyrolysis range of cellulose is 300-400℃, and the products are sugars and aldehydes and ketones; the main pyrolysis range of hemicellulose is 200-300℃, and the products are acids, cyclopentanones and furans. Cellulose and hemicellulose are mainly converted into pyrrole, pyridine and indole during nitrogen-rich pyrolysis. The main pyrolysis range of lignin is 250-500°C, and the products are phenols, aromatic hydrocarbons, etc. When nitrogen-rich pyrolysis occurs, it is mainly converted into aromatic amines (CN202410176052.8). (2) The various inorganic mineral elements (including K, Ca, Na, Mg, Fe, etc.) contained in the biomass itself increase the complexity of the pyrolysis reaction and bio-oil components (CN202010712825.1).

[0007] When single-stage pyrolysis is used, a higher pyrolysis temperature is beneficial to improve the bio-oil yield, but at this time, multiple pyrolysis products are precipitated almost synchronously, making it difficult to effectively regulate the products under fixed catalytic conditions, resulting in complex bio-oil components; when the pyrolysis temperature is low, although some target products have high selectivity in bio-oil, the yield is low due to incomplete pyrolysis. In addition, acids, alcohols, esters, sugars and other substances produced by biomass pyrolysis are not easily converted into nitrogen-containing compounds such as pyridine under non-catalytic ammonia conditions, while the above substances can be converted into aldehydes and ketones through deoxygenation reactions (CN201410213889.1). Considering that the single-stage pyrolysis products are complex and it is difficult to achieve coordinated conversion of multiple components under fixed catalytic conditions, the relative enrichment advantage of the components of graded pyrolysis can be used to regulate the aldehyde-ketone reaction by preparing pyrolysis steam rich in and easy to aldehyde-ketone substances.

[0008] In addition, the composition of aldehydes and ketones obtained under different pyrolysis atmospheres and different types of catalysts varies greatly. For example, in a CO2 atmosphere, CO2 provides oxygen for the carbonylation reaction on the one hand, increasing the yield of ketones; at the same time, CO2 is adsorbed on the catalyst surface, blocking the surface active sites and inhibiting the carbonylation reaction. Metal organic frameworks (MOFs) have great advantages in chemical tunability, insolubility and recyclability due to their highly ordered structure, high specific surface area and precisely customizable composition. In recent years, they have been widely used as heterogeneous porous catalysts such as photocatalysis and CO2 reduction. Therefore, it is necessary to prepare pyridine compounds through targeted regulation by means of raw material pretreatment, high-efficiency catalysts, pyrolysis conditions and other means. Summary of the invention

[0009] The purpose of the present invention is to provide a production process for preparing pyridine-rich bio-oil by pre-treated biomass classification-nitrogen-rich pyrolysis. The production process sets different pyrolysis reaction temperature intervals according to the pyrolysis characteristics of the three major components of biomass, and collects different pyrolysis steams with relatively enriched component contents step by step. Since the pyrolysis products are precipitated step by step during the classification-nitrogen-rich pyrolysis, the complexity of the bio-oil components can be reduced, and the aldehyde-ketone-rich and aldehyde-ketone-prone pyrolysis steam can be selectively prepared through process regulation, and the pyrolysis components that are not easy to aldehyde-ketone-prone can be effectively separated, which significantly improves the yield of pyridine compounds and the selectivity in the classification pyrolysis bio-oil, which is beneficial to the subsequent product separation and processing.

[0010] The production process of the pretreated biomass classification-nitrogen-rich pyrolysis to prepare pyridine-rich bio-oil of the present invention comprises the following steps: (1) First, the biomass is crushed and sieved to obtain biomass powder, and then the biomass powder is added to a washing solution for pretreatment, and then filtered, washed, and dried to obtain pretreated biomass; (2) dispersing the mesoporous molecular sieve in deionized water, then adding a first metal salt solution, stirring, drying, and calcining to prepare a metal oxide-modified mesoporous molecular sieve catalyst; (3) dispersing MOF in deionized water, then adding a second metal salt solution, stirring, drying, and calcining to prepare a bimetallic supported MOF-based catalyst; (4) the pretreated biomass prepared in step (1) and the metal oxide-modified mesoporous molecular sieve catalyst prepared in step (2) are mixed evenly and added to a first pyrolysis reactor, and graded pyrolysis is performed in an oxygen-free atmosphere to obtain first aldehyde- and ketone-rich pyrolysis steam, aldehyde- and ketone-prone pyrolysis steam, and aldehyde- and ketone-prone pyrolysis steam in different temperature ranges; (5) passing the first aldehyde- and ketone-rich pyrolysis steam in step (4) into a second pyrolysis reactor to perform nitrogen-rich pyrolysis under ammonia conditions, and passing the volatile matter into a No. 1 condenser to condense and obtain a first pyridine-rich bio-oil; (6) passing the aldehyde-ketonization pyrolysis steam in step (4) into a catalytic reactor loaded with the bimetallic-supported MOF-based catalyst prepared in step (3), and performing an ex situ catalytic online aldehyde-ketonization reaction on the aldehyde-ketonization pyrolysis steam to obtain a second aldehyde- and ketone-rich pyrolysis steam; (7) passing the second aldehyde- and ketone-rich pyrolysis steam in step (6) into a third pyrolysis reactor to perform nitrogen-rich pyrolysis under ammonia conditions, and passing the volatile matter into a No. 2 condenser to condense and obtain a second pyridine-rich bio-oil; (8) The pyrolysis steam that is not easily aldehyde-ketone-prone in step (4) is passed into condenser No. 3 to condense and obtain bio-oil.

[0011] in: The biomass described in step (1) refers to one or a mixture of wood, crop straw, fruit shell, leaves, bark, food processing residues (residual materials or waste generated during food processing, such as leaves, stems, roots of vegetables, and the remaining parts after processing of meat, seafood, etc.) or model compounds. Among them, the wood is one or more of pine, poplar or camphor; the crop straw is one or more of corn straw, cotton straw or wheat straw, preferably wheat straw; the fruit shell is one or more of coconut shell, grapefruit peel or walnut shell; the model compound is one or more of cellulose, glucose, xylose, xylan, alkali lignin, aldehyde or ketone.

[0012] The particle size of the biomass powder in step (1) is 40-100 mesh.

[0013] When the biomass in step (1) is a model compound, there is no need to add the model compound to a washing solution for pretreatment. The model compound can be directly washed and dried to obtain the pretreated biomass.

[0014] The washing solution in step (1) is one of an acidic solution, an alkaline solution or an oxidizing solution, wherein the acidic solution is a mixture of one of acetic acid, formic acid, oxalic acid or propionic acid and deionized water, and the concentration of the acidic solution is 1-10moL / L; the alkaline solution is a sodium hydroxide solution, and the concentration is 1-10moL / L; the oxidizing solution is a hydrogen peroxide solution, and the concentration is 1-10moL / L.

[0015] In step (1), the mass volume ratio of the biomass powder to the washing solution is 1:25-75, in g / mL; preferably, the mass volume ratio of the biomass powder to the washing solution is 1:25, in g / mL.

[0016] In step (1), the biomass powder is immersed in the prepared washing solution and stirred for 1-5 hours at 20-40° C. using a constant temperature magnetic rotor stirrer for pretreatment. The pretreated raw material is repeatedly washed with deionized water until the pH value of the water filtered out for the last time is 7±0.03, and then the filter residue is dried at 80-200° C. for 8-48 hours to obtain the pretreated biomass.

[0017] The mesoporous molecular sieve described in step (2) refers to one or more of the M41S series, MSU series or SBA series, the M41S series is one of the MCM-41 mesoporous molecular sieve, MCM-22 mesoporous molecular sieve, MCM-48 mesoporous molecular sieve or MCM-50 mesoporous molecular sieve, the MSU series is one of the MSU-1 mesoporous molecular sieve, and the SBA series is one of the SBA-15 mesoporous molecular sieve or SBA-16 mesoporous molecular sieve; preferably, the mesoporous molecular sieve is MCM-41.

[0018] In step (2), the mass ratio of the mesoporous molecular sieve to the deionized water is 1:1-3, and preferably the mass ratio of the mesoporous molecular sieve to the deionized water is 1:2.

[0019] In step (2), the first metal salt solution is a solution obtained by mixing one or more of Co (NO3)2·6H2O, Ni (NO3)2·6H2O, Zr(NO3)4·10H2O, Ce(NO3)3·6H2O, Mn(NO3)2·4H2O or Mg (NO3)2·6H2O with deionized water, and the concentration of the first metal salt solution is 0.1-5moL / L.

[0020] Step (2) adding the first metal salt solution into a mixed solution of the mesoporous molecular sieve and deionized water and stirring the mixture.

[0021] The metal loading in the metal oxide-modified mesoporous molecular sieve catalyst in step (2) is 5-30 wt %, preferably 10 wt %.

[0022] In step (2), a constant temperature magnetic rotor stirrer is used to stir the mixture of the mesoporous molecular sieve and deionized water and the first metal salt solution at 20-60° C. for 1-12 h, then dry at 80-200° C. for 8-24 h, and finally calcine at 500-800° C. for 4-12 h to prepare a metal oxide modified mesoporous molecular sieve catalyst.

[0023] In step (2), the metal oxide-modified mesoporous molecular sieve catalyst is prepared by an equal volume impregnation method.

[0024] The MOF in step (3) refers to one or more of a reticulated metal-organic framework series material (IRMOFs), a zeolite imidazolate framework series material (ZIFs), a pore-channel framework series material (PCNs) or a Lavahill framework series material (MIL).

[0025] Among them, the reticular metal-organic framework series materials (IRMOFs) are one of IRMOFs-1, IRMOFs-3, IRMOFs-6 or IRMOFs-8; the zeolite imidazolate framework series materials (ZIFs) are one of ZIF-8, ZIF-11 or ZIF-67; the pore-channel framework series materials (PCNs) are one of PCN-9, PCN-14 or PCN-53; the Lavahill framework series materials (MIL) are one of MIL-53, MIL-100 or MIL-101.

[0026] Preferably, the MOF in step (3) is ZIF-8.

[0027] In step (3), MOF is dispersed in deionized water, and the mass ratio of MOF to deionized water is 1:1-3, preferably 1:2.

[0028] In step (3), the second metal salt solution is a solution obtained by mixing any two of Ce(NO3)3, RuCl3, Co(NO3)2, Ni(NO3)2, Zr(NO3)4, Mn(NO3)2 or Mg(NO3)2 with deionized water, and the concentration of the second metal salt solution is 0.1-2 mol / L, preferably 0.5 mol / L.

[0029] In step (3), the two metal salt solutions in the second metal salt solution are sequentially added to the mixed solution of MOF and deionized water.

[0030] The metal loading in the bimetallic MOF-based catalyst in step (3) is 5-30 wt%, and the loading of the two metals is the same, preferably 10 wt%.

[0031] In step (3), a constant temperature magnetic rotor stirrer is used to stir the mixture of MOF and deionized water and the second metal salt solution at 20-60° C. for 1-12 h, then dry at 80-200° C. for 8-24 h, and finally calcine at 500-800° C. for 4-12 h to prepare a bimetallic supported MOF-based catalyst.

[0032] In step (4), the mass ratio of the pretreated biomass to the metal oxide modified mesoporous molecular sieve catalyst is 1:1-5, preferably 1:1.

[0033] The oxygen-free atmosphere described in step (4) refers to a mixture of one or more of nitrogen, argon, helium, CO2 or CO, and the gas flow rate is 100-200 mL / min, preferably 200 mL / min.

[0034] The graded pyrolysis in step (4) is to set multiple temperature intervals within 20-800°C, preferably 20-250°C, 250-300°C, 300-400°C, 400-600°C; the insulation time of each temperature interval is 3s-30min, preferably 15min; the pyrolysis heating rate is 2-15°C / min, preferably 10°C / min.

[0035] The second pyrolysis reactor in step (5) is heated and kept warm synchronously with the first pyrolysis reactor in step (4), and the pyrolysis temperature range, pyrolysis heating rate, holding time and gas flow rate of nitrogen-rich pyrolysis under ammonia conditions are consistent with the reaction conditions when the first aldehyde-rich ketone pyrolysis steam is obtained in the first pyrolysis reactor in step (4).

[0036] The ammonia condition in step (5) means that the carrier gas is pure NH3 or a mixture of NH3 and other inert gases, and the other inert gas is one of argon or nitrogen, preferably pure NH3.

[0037] The mass of the bimetallic supported MOF-based catalyst in step (6) is 1-5 times the mass of the pretreated biomass.

[0038] The catalytic reactor in step (6) is heated and kept warm synchronously with the first pyrolysis reactor in step (4), and the temperature range, heating rate, holding time and gas flow rate of the heterogeneous catalytic online aldehyde-ketonization reaction are consistent with the reaction conditions when the aldehyde-ketonization pyrolysis steam is obtained in the first pyrolysis reactor in step (4).

[0039] The catalytic reactor in step (6) is an oxygen-free atmosphere, and the gas type is consistent with the oxygen-free atmosphere in step (4).

[0040] The ammonia condition in step (7) means that the carrier gas is pure NH3 or a mixture of NH3 and other inert gases, and the other inert gas is one of argon or nitrogen, preferably pure NH3.

[0041] The third pyrolysis reactor in step (7) is heated and kept warm synchronously with the first pyrolysis reactor in step (4), and the pyrolysis temperature range, pyrolysis heating rate, holding time and gas flow rate of nitrogen-rich pyrolysis under ammonia conditions are consistent with the reaction conditions when the pyrolysis steam easily aldehyde-ketonized is obtained in the first pyrolysis reactor in step (4).

[0042] The condensation temperature of the No. 1 condenser in step (5), the No. 2 condenser in step (7) and the No. 3 condenser in step (8) is -30-30°C.

[0043] Compared with the prior art, the present invention has the following beneficial effects: (1) The production process of preparing pyridine-rich bio-oil by grading and nitrogen-enriched pyrolysis of pretreated biomass described in the present invention, wherein the grading and nitrogen-enriched pyrolysis is to set different pyrolysis reaction temperature intervals according to the pyrolysis characteristics of the three major components of biomass, and collect different pyrolysis steams with relatively rich component contents step by step. Under nitrogen-enriched pyrolysis conditions, the aldehyde- and ketone-rich pyrolysis steam is converted into pyridine-rich bio-oil. For the pyrolysis steam with low aldehyde- and ketone-content, further online catalytic regulation is performed to convert the components that are easy to aldehyde and ketone into aldehydes and ketones, and then nitrogen-enriched pyrolysis conversion is performed. The pyrolysis steam with a high content of components that are not easy to aldehyde and ketone is used to prepare liquid fuels or other chemicals, thereby realizing the graded and quality-based high-value utilization of all components of biomass. Since the pyrolysis products are precipitated step by step during the graded and nitrogen-enriched pyrolysis, the complexity of the bio-oil components can be reduced, and the aldehyde- and ketone-rich pyrolysis steam and the aldehyde- and ketone-rich pyrolysis steam that are easy to aldehyde and ketone are selectively prepared through process regulation, and the pyrolysis components that are not easy to aldehyde and ketone are effectively separated, which significantly improves the yield of pyridine compounds and the selectivity in the graded pyrolysis bio-oil, which is beneficial to the subsequent product separation and processing.

[0044] (2) The production process of preparing pyridine-rich bio-oil by pre-treatment biomass classification-nitrogen-rich pyrolysis described in the present invention can effectively remove impurities and inorganic salts in the raw materials by acid washing, alkali washing or oxidation pre-treatment of biomass raw materials, thereby improving pyrolysis efficiency and product quality. The graded pyrolysis technology is adopted to set different temperature ranges according to the pyrolysis characteristics of the three major components of biomass (cellulose, hemicellulose and lignin), and collect pyrolysis steam with relatively enriched component content step by step. This method effectively reduces the complexity of bio-oil components and lays the foundation for subsequent directional conversion and product separation.

[0045] (3) The production process of preparing pyridine-rich bio-oil by pretreated biomass classification and nitrogen-rich pyrolysis described in the present invention prepares aldehyde- and ketone-rich pyrolysis steam through in situ / ex situ catalytic directional regulation during the classification pyrolysis process. This classification and quality separation treatment method not only significantly improves the yield and selectivity of pyridine compounds in bio-oil under nitrogen-rich pyrolysis conditions, but also realizes the high-value utilization of all components of biomass, avoiding the complicated component separation steps in traditional processes.

[0046] (4) The production process for preparing pyridine-rich bio-oil by pre-treated biomass classification-nitrogen-rich pyrolysis described in the present invention uses a mesoporous molecular sieve catalyst modified by metal oxide for in-situ catalysis, which can effectively regulate the composition of the pyrolysis product. The introduction of metal oxides enhances the acidity and redox properties of the mesoporous molecular catalyst, which is beneficial to the efficient conversion of biomass. At the same time, the present invention uses a bimetallic-loaded MOF-based catalyst for online catalytic regulation of aldehyde-ketonization pyrolysis steam. MOF materials have a highly ordered structure, a high specific surface area, and a precisely customizable composition, and show great advantages in chemical adjustability, insolubility, and recyclability. The loading of bimetals further improves the performance of the catalyst, which is beneficial to the efficient generation of aldehydes and ketones, and has strong stability, meets the characteristics of high efficiency, low cost, and environmental protection, and has strong practicality. DETAILED DESCRIPTION

[0047] The present invention is further described below with reference to the embodiments.

[0048] Example 1 The production process for preparing pyridine-rich bio-oil by pretreated biomass classification-nitrogen-rich pyrolysis described in Example 1 is composed of the following steps: (1) Coconut shell was selected as raw material, and the coconut shell was crushed to obtain coconut shell powder with a particle size of 40 mesh. Then, 10 g of coconut shell powder was added into a beaker containing 250 mL of acetic acid solution (concentration of 1 mol / L) and stirred at 20 °C for 2 h using a constant temperature magnetic rotor stirrer. The pretreated raw material was repeatedly washed with deionized water until the pH value of the water filtered out for the last time was 7±0.03. The filter residue was then dried at 105 °C for 24 h to obtain coconut shell powder after acid washing pretreatment.

[0049] (2) Using the impregnation method, 20 g of MCM-41 mesoporous molecular sieve (purchased from Tianjin Nanhua Catalyst Co., Ltd.) was dispersed in 40 g of deionized water, and a Zr(NO3)4 solution with a concentration of 0.5 mol / L was added to make the metal loading amount 10 wt%. Using a constant temperature magnetic rotor stirrer, the mixed solution of the deionized water solution of MCM-41 and the Zr(NO3)4 solution was stirred at 40 °C for 6 h, then dried at 105 °C for 12 h, and finally calcined at 600 °C for 4 h to prepare ZrO2-MCM-41.

[0050] (3) Using the impregnation method, 20 g of ZIF-8 (purchased from Shanghai Kaishu Chemical Technology Co., Ltd.) was dispersed in 40 g of deionized water. A 0.5 mol / L Ce(NO3)3 solution and a 0.5 mol / L RuCl3 solution were added to 100 mL of deionized water. The Ce loading was 5 wt% and the Ru loading was 5 wt%. Using a constant temperature magnetic rotor stirrer, the deionized water solution of ZIF-8 and the second metal salt solution were stirred at 40 °C for 6 h, then dried at 105 °C for 12 h, and finally calcined at 600 °C for 4 h to obtain RuCe-ZIF-8.

[0051] (4) 10 g of the acid-pretreated coconut shell powder prepared in step (1) and 10 g of the ZrO2-MCM-41 prepared in step (2) were mixed evenly and added to the first pyrolysis reactor for graded pyrolysis under Ar atmosphere. The gas flow rate was 100 mL / min, the graded pyrolysis temperatures were 300°C, 400°C and 600°C, respectively, the heating rate was 10°C / min, and each stage was kept warm for 15 min. The first aldehyde-ketone-rich pyrolysis steam was obtained in the range of 20-300°C, the aldehyde-ketone-prone pyrolysis steam was obtained in the range of 300-400°C, and the aldehyde-ketone-prone pyrolysis steam was obtained in the range of 400-600°C.

[0052] (5) The second pyrolysis reactor, the third pyrolysis reactor and the catalytic reactor are heated and kept warm synchronously with the first pyrolysis reactor. In the temperature range of 20-300°C, the first aldehyde- and ketone-rich pyrolysis steam obtained in step (4) is introduced into the second pyrolysis reactor, and nitrogen-rich pyrolysis is carried out under a pure NH3 atmosphere at a gas flow rate of 100 mL / min. The volatile matter is introduced into a No. 1 condenser and condensed at -10°C to obtain a first pyridine-rich bio-oil.

[0053] (6) In the temperature range of 300-400 °C, the aldehyde-ketonization pyrolysis steam produced in step (4) was first introduced into a catalytic reactor loaded with 10 g of RuCe-ZIF-8 catalyst to carry out heterogeneous catalytic online aldehyde-ketonization reaction under Ar atmosphere at a gas flow rate of 100 mL / min to obtain a second aldehyde- and ketone-rich pyrolysis steam.

[0054] (7) In the temperature range of 300-400 °C, the second aldehyde- and ketone-rich pyrolysis steam obtained in step (6) is introduced into a third pyrolysis reactor for nitrogen-rich pyrolysis under a pure NH3 atmosphere at a gas flow rate of 100 mL / min. The volatile matter is introduced into a No. 2 condenser and condensed at -10 °C to obtain a second pyridine-rich bio-oil.

[0055] (8) In the temperature range of 400-600°C, the pyrolysis steam that is not easily aldehyde-ketone-prone in step (4) is passed into condenser No. 3 and condensed at -10°C to obtain bio-oil.

[0056] Example 2 The production process for preparing pyridine-rich bio-oil by pretreated biomass classification-nitrogen-rich pyrolysis described in Example 2 is composed of the following steps: (1) Cotton straw was selected as raw material, and the cotton straw was crushed to obtain cotton straw powder with a particle size of 60 mesh. Then, 10 g of cotton straw powder was added to a beaker containing 300 mL of formic acid solution (concentration of 1 mol / L) and stirred at 30 °C for 4 h using a constant temperature magnetic rotor stirrer. The pretreated raw material was repeatedly washed with deionized water until the pH value of the water filtered out for the last time was 7±0.03. The filter residue was then dried at 105 °C for 12 h to obtain cotton straw after acid washing pretreatment.

[0057] (2) Using the impregnation method, 15 g of SBA-15 mesoporous molecular sieve (purchased from Tianjin Nanhua Catalyst Co., Ltd.) was dispersed in 45 g of deionized water, and a Co (NO3)2 solution with a concentration of 0.3 mol / L was added to make the metal loading amount 10 wt%. Using a constant temperature magnetic rotor stirrer, the deionized water solution of SBA-15 mesoporous molecular sieve and the Co (NO3)2 solution were stirred at 40 °C for 6 h, then dried at 105 °C for 12 h, and finally calcined at 600 °C for 4 h to prepare Co3O4-SBA-15.

[0058] (3) Using the impregnation method, 15 g of ZIF-11 (purchased from Shanghai Kaishu Chemical Technology Co., Ltd.) was dispersed in 45 g of deionized water. A 0.5 mol / L Ni (NO3)2 solution and a 0.5 mol / L Mg (NO3)2 solution were added to 100 mL of deionized water. The Ni loading was 8 wt% and the Mg loading was 8 wt%. Using a constant temperature magnetic rotor stirrer, the mixed solution of ZIF-8 solution and the second metal salt solution was stirred at 40 °C for 6 h, then dried at 105 °C for 12 h, and finally calcined at 550 °C for 6 h to obtain NiMg-ZIF-11.

[0059] (4) 5 g of the acid-pretreated cotton straw prepared in step (1) and 10 g of the Co3O4-SBA-15 prepared in step (2) were mixed evenly and added to the first pyrolysis reactor for graded pyrolysis under a CO2 atmosphere. The gas flow rate was 100 mL / min, the graded pyrolysis temperatures were 300°C, 400°C and 600°C, respectively, the heating rate was 12°C / min, and each stage was kept warm for 20 min. In the temperature range of 20-300°C, pyrolysis steam that was not easy to aldehyde-ketone was obtained, in the temperature range of 300-400°C, first aldehyde-ketone-rich pyrolysis steam was obtained, and in the temperature range of 400-600°C, pyrolysis steam that was easy to aldehyde-ketone was obtained.

[0060] (5) In the temperature range of 20-300°C, the pyrolysis steam that is not easily aldehyde-ketone-produced in step (4) is passed into condenser No. 3 and condensed at -10°C to obtain bio-oil.

[0061] (6) The second pyrolysis reactor, the third pyrolysis reactor and the catalytic reactor are heated and kept warm synchronously with the first pyrolysis reactor. In the temperature range of 300-400°C, the first aldehyde- and ketone-rich pyrolysis steam obtained in step (4) is introduced into the second pyrolysis reactor, and nitrogen-rich pyrolysis is carried out under a pure NH3 atmosphere at a gas flow rate of 100 mL / min. The volatile matter is introduced into a No. 1 condenser and condensed at -10°C to obtain a first pyridine-rich bio-oil.

[0062] (7) In the temperature range of 400-600 °C, the aldehyde-ketonization pyrolysis steam produced in step (4) is first introduced into a catalytic reactor loaded with 10 g of NiMg-ZIF-11 catalyst to carry out an heterogeneous catalytic online aldehyde-ketonization reaction under a CO2 atmosphere at a gas flow rate of 100 mL / min to obtain a second aldehyde- and ketone-rich pyrolysis steam.

[0063] (8) In the temperature range of 400-600°C, the second aldehyde- and ketone-rich pyrolysis steam obtained in step (7) is introduced into a third pyrolysis reactor for nitrogen-rich pyrolysis under a pure NH3 atmosphere at a gas flow rate of 100 mL / min. The volatile matter is introduced into a No. 2 condenser and condensed at -10°C to obtain a second pyridine-rich bio-oil.

[0064] Example 3 The process for preparing pyridine compounds by pre-treatment biomass classification-nitrogen-enriched pyrolysis described in Example 3 is composed of the following steps: (1) Pine wood was selected as the raw material, and the pine wood was crushed and sieved to obtain pine wood powder with a particle size of 100 mesh. Then, 10 g of pine wood powder was added to a beaker containing 400 mL of H2O2 solution (concentration of 3 mol / L) and stirred at 25 °C for 2 h using a constant temperature magnetic rotor stirrer. The pretreated raw material was repeatedly washed with deionized water until the pH value of the water filtered out for the last time was 7±0.03. The filter residue was then dried at 120 °C for 24 h to obtain the pine wood powder after oxidation pretreatment.

[0065] (2) Using the impregnation method, 30 g of MCM-22 mesoporous molecular sieve (purchased from Tianjin Nanhua Catalyst Co., Ltd.) was dispersed in 80 g of deionized water, and a 0.5 mol / L Mg (NO3)2 solution was added to make the metal loading amount 5 wt%. Using a constant temperature magnetic rotor stirrer, the mixed solution of the deionized water solution of MCM-22 mesoporous molecular sieve and Mg (NO3)2 was stirred at 40 °C for 6 h, then dried at 105 °C for 12 h, and finally calcined at 600 °C for 4 h to prepare MgO-MCM-22.

[0066] (3) Using the impregnation method, 30 g of MIL-101 (purchased from Tianjin Nanhua Catalyst Co., Ltd.) was dispersed in 60 g of deionized water. A 1.5 mol / L Ni (NO3)2 solution and a 1.5 mol / L Co (NO3)2 solution were added to 100 mL of deionized water. The Ni loading was 10 wt% and the Co loading was 10 wt%. Using a constant temperature magnetic rotor stirrer, the mixed solution of the deionized water solution of MIL-101 and the metal salt solution was stirred at 30 °C for 8 h, then dried at 105 °C for 24 h, and calcined at 650 °C for 4 h to obtain CoNi-MIL-101.

[0067] (4) 15 g of the oxidatively pretreated pine wood powder prepared in step (1) and 15 g of the MgO-MCM-22 prepared in step (2) were mixed evenly and added to the first pyrolysis reactor for graded pyrolysis under N2 atmosphere. The gas flow rate was 100 mL / min, the graded pyrolysis temperatures were 250°C, 400°C and 600°C, respectively, the heating rate was 5°C / min, and each stage was kept warm for 25 min. The first aldehyde-ketone-rich pyrolysis steam was obtained in the temperature range of 20-250°C, the aldehyde-ketone-prone pyrolysis steam was obtained in the temperature range of 250-400°C, and the aldehyde-ketone-prone pyrolysis steam was obtained in the temperature range of 400-600°C.

[0068] (5) The second pyrolysis reactor, the third pyrolysis reactor and the catalytic reactor are heated and kept warm synchronously with the first pyrolysis reactor. In the temperature range of 20-250°C, the first aldehyde- and ketone-rich pyrolysis steam obtained in step (4) is introduced into the second pyrolysis reactor, and nitrogen-rich pyrolysis is carried out in a 5 vol% NH3 / 95 vol% N2 atmosphere at a gas flow rate of 100 mL / min. The volatile matter is introduced into a No. 1 condenser and condensed at -20°C to obtain the first pyridine-rich bio-oil.

[0069] (6) In the temperature range of 250-400 °C, the aldehyde-ketonization pyrolysis steam produced in step (4) is first introduced into a catalytic reactor loaded with 15 g of CoNi-MIL-101 catalyst to carry out heterogeneous catalytic online aldehyde-ketonization reaction under a CO2 atmosphere at a gas flow rate of 100 mL / min to obtain a second aldehyde- and ketone-rich pyrolysis steam.

[0070] (7) In the temperature range of 250-400°C, the second aldehyde- and ketone-rich pyrolysis steam obtained in step (6) is introduced into a third pyrolysis reactor, and nitrogen-rich pyrolysis is carried out in an atmosphere of 5 vol% NH3 / 95 vol% N2 at a gas flow rate of 100 mL / min. The volatile matter is introduced into a No. 2 condenser and condensed at -20°C to obtain a second pyridine-rich bio-oil.

[0071] (8) In the temperature range of 400-600°C, the pyrolysis steam that is not easily aldehyde-ketone-prone in step (4) is passed into condenser No. 3 and condensed at -20°C to obtain bio-oil.

[0072] Example 4 The production process for preparing pyridine-rich bio-oil by pretreated biomass classification-nitrogen-rich pyrolysis described in Example 4 is composed of the following steps: (1) Grapefruit peel was selected as the raw material, and the grapefruit peel was crushed and sieved to obtain grapefruit peel powder with a particle size of 40 mesh. Then, 20 g of grapefruit peel powder was added to a beaker containing 500 mL of NaOH solution (concentration of 2.5 mol / L) and stirred at 20 °C for 4 h using a constant temperature magnetic rotor stirrer. The pretreated raw material was repeatedly washed with deionized water until the pH value of the water filtered out for the last time was 7±0.03. The filter residue was then dried at 105 °C for 24 h to obtain the grapefruit peel powder after alkali washing pretreatment.

[0073] (2) Using the impregnation method, 15 g of MSU-1 mesoporous molecular sieve (purchased from Tianjin Nanhua Catalyst Co., Ltd.) was dispersed in 30 g of deionized water, and a Ni (NO3)2 solution with a concentration of 1.5 mol / L was added to make the metal loading amount 20 wt%. Using a constant temperature magnetic rotor stirrer, the mixed solution of the deionized water solution of MSU-1 and the Ni (NO3)2 solution was stirred at 40 °C for 6 h, then dried at 105 °C for 12 h, and finally calcined at 600 °C for 4 h to prepare NiO-MSU-1.

[0074] (3) Using the impregnation method, 15 g of ZIF-8 (purchased from Shanghai Kaishu Chemical Technology Co., Ltd.) was dispersed in 45 g of deionized water. A 0.5 mol / L Zr(NO3)4 solution and a 0.5 mol / L Mg(NO3)2 solution were added to 100 mL of deionized water. The Zr loading was 6 wt% and the Mg loading was 6 wt%. Using a constant temperature magnetic rotor stirrer, the mixed solution of the deionized water solution of ZIF-8 and the metal salt solution was stirred at 40 °C for 6 h, then dried at 105 °C for 12 h, and calcined at 500 °C for 4 h to obtain ZrMg-ZIF-8.

[0075] (4) 8 g of the alkali-washed pretreated grapefruit peel powder prepared in step (1) and 16 g of the NiO-MSU-1 prepared in step (2) were mixed evenly and added to the first pyrolysis reactor for graded pyrolysis under Ar atmosphere. The gas flow rate was 120 mL / min, the graded pyrolysis temperatures were 250°C, 350°C and 550°C, respectively, the heating rate was 7.5°C / min, and each stage was kept warm for 30 min. The first aldehyde-ketone-rich pyrolysis steam was obtained in the temperature range of 20-250°C, the aldehyde-ketone-prone pyrolysis steam was obtained in the temperature range of 250-350°C, and the aldehyde-ketone-prone pyrolysis steam was obtained in the temperature range of 350-550°C.

[0076] (5) The second pyrolysis reactor, the third pyrolysis reactor and the catalytic reactor are heated and kept warm synchronously with the first pyrolysis reactor. In the temperature range of 20-250°C, the first aldehyde- and ketone-rich pyrolysis steam obtained in step (4) is introduced into the second pyrolysis reactor, and nitrogen-rich pyrolysis is carried out in a 10 vol% NH3 / 90 vol% N2 atmosphere at a gas flow rate of 120 mL / min. The volatile matter is introduced into a No. 1 condenser and condensed at -15°C to obtain a first pyridine-rich bio-oil.

[0077] (6) In the temperature range of 250-350 °C, the aldehyde-ketonization pyrolysis steam produced in step (4) was first introduced into a catalytic reactor loaded with 16 g of ZrMg-ZIF-8 catalyst to carry out heterogeneous catalytic online aldehyde-ketonization reaction under Ar atmosphere at a gas flow rate of 100 mL / min to obtain a second aldehyde- and ketone-rich pyrolysis steam.

[0078] (7) In the temperature range of 250-350°C, the second aldehyde- and ketone-rich pyrolysis steam obtained in step (6) is introduced into a third pyrolysis reactor for nitrogen-rich pyrolysis in a 10 vol% NH3 / 90 vol% N2 atmosphere at a gas flow rate of 120 mL / min. The volatile matter is introduced into a No. 2 condenser and condensed at -15°C to obtain a second pyridine-rich bio-oil.

[0079] (8) In the temperature range of 350-550°C, the pyrolysis steam that is not easily aldehyde-ketone-prone in step (4) is passed into condenser No. 3 and condensed at -15°C to obtain bio-oil.

[0080] Comparative Example 1 The difference between this comparative example 1 and example 1 is that the coconut shell powder is not subjected to acid washing pretreatment, and the steps are as follows: (1) Coconut shell is selected as raw material, the coconut shell is crushed, and coconut shell powder with a particle size of 40 mesh is sieved out.

[0081] (2) Using the impregnation method, 20 g of MCM-41 mesoporous molecular sieve (purchased from Tianjin Nanhua Catalyst Co., Ltd.) was dispersed in 40 g of deionized water, and a Zr(NO3)4 solution with a concentration of 0.5 mol / L was added to make the metal loading amount 10 wt%. Using a constant temperature magnetic rotor stirrer, the mixed solution of MCM-41 and Zr(NO3)4 was stirred at 40 °C for 6 h, then dried at 105 °C for 12 h, and calcined at 600 °C for 4 h to prepare ZrO2-MCM-41.

[0082] (3) Using the impregnation method, 20 g of ZIF-8 (purchased from Shanghai Kaishu Chemical Technology Co., Ltd.) was dispersed in 40 g of deionized water. A 0.5 mol / L Ce(NO3)3 solution and a 0.5 mol / L RuCl3 solution were added to 100 mL of deionized water. The Ce loading was 5 wt% and the Ru loading was 5 wt%. Using a constant temperature magnetic rotor stirrer, the mixture of ZIF-8 and deionized water was stirred with the second metal salt solution at 40 °C for 6 h, then dried at 105 °C for 12 h, and calcined at 600 °C for 4 h to obtain RuCe-ZIF-8.

[0083] (4) 10 g of the acid-pretreated coconut shell powder prepared in step (1) and 10 g of the ZrO2-MCM-41 prepared in step (2) were mixed evenly and added to the first pyrolysis reactor for graded pyrolysis under Ar atmosphere. The gas flow rate was 100 mL / min, the graded pyrolysis temperatures were 300°C, 400°C and 600°C, respectively, the heating rate was 10°C / min, and each stage was kept warm for 15 min. The first aldehyde-ketone-rich pyrolysis steam was obtained in the range of 20-300°C, the aldehyde-ketone-prone pyrolysis steam was obtained in the range of 300-400°C, and the aldehyde-ketone-prone pyrolysis steam was obtained in the range of 400-600°C.

[0084] (5) The second pyrolysis reactor, the third pyrolysis reactor and the catalytic reactor are heated and kept warm synchronously with the first pyrolysis reactor. In the temperature range of 20-300°C, the first aldehyde- and ketone-rich pyrolysis steam obtained in step (4) is introduced into the second pyrolysis reactor, and nitrogen-rich pyrolysis is carried out under a pure NH3 atmosphere at a gas flow rate of 100 mL / min. The volatile matter is introduced into a No. 1 condenser and condensed at -10°C to obtain a first pyridine-rich bio-oil.

[0085] (6) In the temperature range of 300-400 °C, the aldehyde-ketonization pyrolysis steam produced in step (4) was first introduced into a catalytic reactor loaded with 10 g of RuCe-ZIF-8 catalyst to carry out heterogeneous catalytic online aldehyde-ketonization reaction under Ar atmosphere at a gas flow rate of 100 mL / min to obtain a second aldehyde- and ketone-rich pyrolysis steam.

[0086] (7) In the temperature range of 300-400 °C, the second aldehyde- and ketone-rich pyrolysis steam obtained in step (6) is introduced into the second-stage pyrolysis reactor for nitrogen-rich pyrolysis under a pure NH3 atmosphere at a gas flow rate of 100 mL / min. The volatile matter is introduced into a No. 2 condenser and condensed at -10 °C to obtain a second pyridine-rich bio-oil.

[0087] (8) In the temperature range of 400-600°C, the pyrolysis steam that is not easily aldehyde-ketone-prone in step (4) is passed into condenser No. 3 and condensed at -10°C to obtain bio-oil.

[0088] Comparative Example 2 The difference between this comparative example 2 and example 1 is that no in-situ catalysis is performed in the graded pyrolysis, and the steps are as follows: (1) Coconut shell was selected as raw material, and the coconut shell was crushed to obtain coconut shell powder with a particle size of 40 mesh. Then, 10 g of coconut shell powder was added into a beaker containing 250 mL of acetic acid solution (concentration of 1 mol / L) and stirred at 20 °C for 2 h using a constant temperature magnetic rotor stirrer. The pretreated raw material was repeatedly washed with deionized water until the pH value of the water filtered out for the last time was 7±0.03. The filter residue was then dried at 105 °C for 24 h to obtain coconut shell powder after acid washing pretreatment.

[0089] (2) Using the impregnation method, 20 g of ZIF-8 (purchased from Shanghai Kaishu Chemical Technology Co., Ltd.) was dispersed in 40 g of deionized water. A 0.5 mol / L Ce(NO3)3 solution and a 0.5 mol / L RuCl3 solution were added to 100 mL of deionized water. The Ce loading was 5 wt% and the Ru loading was 5 wt%. Using a constant temperature magnetic rotor stirrer, the mixture of ZIF-8 and deionized water was stirred with the second metal salt solution at 40 °C for 6 h, then dried at 105 °C for 12 h, and calcined at 600 °C for 4 h to obtain RuCe-ZIF-8.

[0090] (3) Weigh 10 g of the acid-pretreated coconut shell powder prepared in step (1) and add it to the first pyrolysis reactor for graded pyrolysis under Ar atmosphere. The gas flow rate is 100 mL / min, the graded pyrolysis temperatures are 300°C, 400°C and 600°C, respectively, the heating rate is 10°C / min, and each stage is kept warm for 15 min. The first aldehyde-ketone-rich pyrolysis steam is obtained in the range of 20-300°C, the aldehyde-ketone-prone pyrolysis steam is obtained in the range of 300-400°C, and the aldehyde-ketone-prone pyrolysis steam is obtained in the range of 400-600°C.

[0091] (4) The second pyrolysis reactor, the third pyrolysis reactor and the catalytic reactor are heated and kept warm synchronously with the first pyrolysis reactor. In the temperature range of 20-300°C, the first aldehyde- and ketone-rich pyrolysis steam obtained in step (3) is introduced into the second pyrolysis reactor, and nitrogen-rich pyrolysis is carried out under a pure NH3 atmosphere at a gas flow rate of 100 mL / min. The volatile matter is introduced into a No. 1 condenser and condensed at -10°C to obtain the first pyridine-rich bio-oil.

[0092] (5) In the temperature range of 300-400 °C, the aldehyde-ketonization pyrolysis steam produced in step (3) was first introduced into a catalytic reactor loaded with 10 g of RuCe-ZIF-8 catalyst to carry out heterogeneous catalytic online aldehyde-ketonization reaction under Ar atmosphere at a gas flow rate of 100 mL / min to obtain a second aldehyde- and ketone-rich pyrolysis steam.

[0093] (6) In the temperature range of 300-400 °C, the second aldehyde- and ketone-rich pyrolysis steam obtained in step (5) is introduced into a third pyrolysis reactor for nitrogen-rich pyrolysis under a pure NH3 atmosphere at a gas flow rate of 100 mL / min. The volatile matter is introduced into a No. 2 condenser and condensed at -10 °C to obtain a second pyridine-rich bio-oil.

[0094] (7) In the temperature range of 400-600 °C, the pyrolysis steam that is not easily aldehyde-ketone-prone in step (3) is passed into condenser No. 3 and condensed at -10 °C to obtain bio-oil.

[0095] Comparative Example 3 The difference between this comparative example 3 and example 1 is that the pyrolysis steam that is easy to aldehyde ketone is not subjected to ex situ catalysis, and the steps are as follows: (1) Coconut shell was selected as raw material, and the coconut shell was crushed to obtain coconut shell powder with a particle size of 40 mesh. Then, 10 g of coconut shell powder was added into a beaker containing 250 mL of acetic acid solution (concentration of 1 mol / L) and stirred at 20 °C for 2 h using a constant temperature magnetic rotor stirrer. The pretreated raw material was repeatedly washed with deionized water until the pH value of the water filtered out for the last time was 7±0.03. The filter residue was then dried at 105 °C for 24 h to obtain coconut shell powder after acid washing pretreatment.

[0096] (2) Using the impregnation method, 20 g of MCM-41 mesoporous molecular sieve (purchased from Tianjin Nanhua Catalyst Co., Ltd.) was dispersed in 40 g of deionized water, and a Zr(NO3)4 solution with a concentration of 0.5 mol / L was added to make the metal loading amount 10 wt%. Using a constant temperature magnetic rotor stirrer, the mixed solution of the deionized water solution of MCM-41 and the Zr(NO3)4 solution was stirred at 40 °C for 6 h, then dried at 105 °C for 12 h, and calcined at 600 °C for 4 h to prepare ZrO2-MCM-41.

[0097] (3) 10 g of the acid-pretreated coconut shell powder prepared in step (1) and 10 g of the ZrO2-MCM-41 prepared in step (2) were mixed evenly and added to the first pyrolysis reactor for graded pyrolysis under Ar atmosphere. The gas flow rate was 100 mL / min, the graded pyrolysis temperatures were 300°C, 400°C and 600°C, respectively, the heating rate was 10°C / min, and each stage was kept warm for 15 min. The first aldehyde-ketone-rich pyrolysis steam was obtained in the range of 20-300°C, the aldehyde-ketone-prone pyrolysis steam was obtained in the range of 300-400°C, and the aldehyde-ketone-prone pyrolysis steam was obtained in the range of 400-600°C.

[0098] (4) The second pyrolysis reactor and the third pyrolysis reactor are heated and kept warm synchronously with the first pyrolysis reactor. In the temperature range of 20-300 °C, the first aldehyde- and ketone-rich pyrolysis steam obtained in step (3) is introduced into the second pyrolysis reactor, and nitrogen-rich pyrolysis is carried out under a pure NH3 atmosphere at a gas flow rate of 100 mL / min. The volatile matter is introduced into a No. 1 condenser and condensed at -10 °C to obtain pyridine-rich bio-oil.

[0099] (5) In the temperature range of 300-400 °C, the aldehyde-ketone pyrolysis steam produced in step (3) is introduced into a third pyrolysis reactor to carry out nitrogen-rich pyrolysis in a pure NH3 atmosphere at a gas flow rate of 100 mL / min. The volatile matter is introduced into a No. 2 condenser and condensed at -10 °C to obtain a first bio-oil (the bio-oil is a nitrogen-rich bio-oil).

[0100] (6) In the temperature range of 400-600°C, the pyrolysis steam that is not easily aldehyde-ketone-prone in step (3) is passed into condenser No. 3 and condensed at -10°C to obtain a second bio-oil.

[0101] Comparative Example 4 The difference between this comparative example 4 and example 1 is that nitrogen-enriched pyrolysis is not performed, and the steps are as follows: (1) Coconut shell was selected as raw material, and the coconut shell was crushed to obtain coconut shell powder with a particle size of 40 mesh. Then, 10 g of coconut shell powder was added into a beaker containing 250 mL of acetic acid solution (concentration of 1 mol / L) and stirred at 20 °C for 2 h using a constant temperature magnetic rotor stirrer. The pretreated raw material was repeatedly washed with deionized water until the pH value of the water filtered out for the last time was 7±0.03. The filter residue was then dried at 105 °C for 24 h to obtain coconut shell powder after acid washing pretreatment.

[0102] (2) Using the impregnation method, 20 g of MCM-41 mesoporous molecular sieve (purchased from Tianjin Nanhua Catalyst Co., Ltd.) was dispersed in 40 g of deionized water, and a Zr(NO3)4 solution with a concentration of 0.5 mol / L was added to make the metal loading amount 10 wt%. Using a constant temperature magnetic rotor stirrer, the mixed solution of the deionized water solution of MCM-41 and the Zr(NO3)4 solution was stirred at 40 °C for 6 h, then dried at 105 °C for 12 h, and finally calcined at 600 °C for 4 h to prepare ZrO2-MCM-41.

[0103] (3) Using the impregnation method, 20 g of ZIF-8 (purchased from Shanghai Kaishu Chemical Technology Co., Ltd.) was dispersed in 40 g of deionized water. A 0.5 mol / L Ce(NO3)3 solution and a 0.5 mol / L RuCl3 solution were added to 100 mL of deionized water. The Ce loading was 5 wt% and the Ru loading was 5 wt%. Using a constant temperature magnetic rotor stirrer, the mixture of ZIF-8 and deionized water was stirred with the second metal salt solution at 40 °C for 6 h, then dried at 105 °C for 12 h, and calcined at 600 °C for 4 h to obtain RuCe-ZIF-8.

[0104] (4) 10 g of the acid-pretreated coconut shell powder prepared in step (1) and 10 g of the ZrO2-MCM-41 prepared in step (2) were mixed evenly and added to the first pyrolysis reactor for graded pyrolysis under Ar atmosphere. The gas flow rate was 100 mL / min, the graded pyrolysis temperatures were 300°C, 400°C and 600°C, respectively, the heating rate was 10°C / min, and each stage was kept warm for 15 min. The first aldehyde-ketone-rich pyrolysis steam was obtained in the temperature range of 20-300°C, the aldehyde-ketone-prone pyrolysis steam was obtained in the temperature range of 300-400°C, and the aldehyde-ketone-prone pyrolysis steam was obtained in the temperature range of 400-600°C.

[0105] (5) In the temperature range of 20-300°C, the first aldehyde- and ketone-rich pyrolysis steam obtained in step (4) is passed into a No. 1 condenser and condensed at -10°C to obtain a first bio-oil.

[0106] (6) The catalytic reactor and the first pyrolysis reactor are heated and maintained synchronously. In the temperature range of 300-400 °C, the pyrolysis steam easily oxidized to aldehydes and ketones produced in step (4) is introduced into the catalytic reactor loaded with 10 g of RuCe-ZIF-8 catalyst, and an ex situ catalytic online aldehyde ketone reaction is carried out under Ar atmosphere at a gas flow rate of 100 mL / min to obtain a second pyrolysis steam rich in aldehydes and ketones.

[0107] (7) In the temperature range of 300-400° C., the second aldehyde- and ketone-rich pyrolysis steam obtained in step (6) is passed into a No. 2 condenser and condensed at −10° C. to obtain a second bio-oil.

[0108] (8) In the temperature range of 400-600°C, the pyrolysis steam that is not easily aldehyde-ketone-produced in step (4) is introduced into condenser No. 3 and condensed at -10°C to obtain a third bio-oil.

[0109] Comparative Example 5 The difference between this comparative example 5 and example 1 is that the coconut shell powder is not subjected to acid washing pretreatment and no catalyst is added. The steps are as follows: (1) Coconut shell is selected as raw material, the coconut shell is crushed, and coconut shell powder with a particle size of 40 mesh is sieved out.

[0110] (2) Weigh 10 g of the coconut shell powder prepared in step (1) and add it into the first pyrolysis reactor. Perform graded pyrolysis under Ar atmosphere with a gas flow rate of 100 mL / min. The graded pyrolysis temperatures are 300°C, 400°C and 600°C, respectively. The heating rate is 10°C / min, and each stage is kept warm for 15 min. The first aldehyde-ketone-rich pyrolysis steam is obtained in the temperature range of 20-300°C, the aldehyde-ketone-prone pyrolysis steam is obtained in the temperature range of 300-400°C, and the aldehyde-ketone-prone pyrolysis steam is obtained in the temperature range of 400-600°C.

[0111] (3) The second pyrolysis reactor and the third pyrolysis reactor are heated and kept warm synchronously with the first pyrolysis reactor. In the temperature range of 20-300 °C, the first aldehyde- and ketone-rich pyrolysis steam obtained in step (2) is introduced into the second pyrolysis reactor, and nitrogen-rich pyrolysis is carried out under a pure NH3 atmosphere at a gas flow rate of 100 mL / min. The volatile matter is introduced into a No. 1 condenser and condensed at -10 °C to obtain the first pyridine-rich bio-oil.

[0112] (4) In the temperature range of 300-400°C, the aldehyde-ketone pyrolysis steam produced in step (2) is introduced into the third pyrolysis reactor for nitrogen-rich pyrolysis in a pure NH3 atmosphere at a gas flow rate of 100 mL / min. The volatile matter is introduced into a No. 2 condenser and condensed at -10°C to obtain the first bio-oil.

[0113] (5) In the temperature range of 400-600°C, the pyrolysis steam that is not easily aldehyde-ketone-prone in step (2) is passed into condenser No. 3 and condensed at -10°C to obtain a second bio-oil.

[0114] The component contents of the bio-oils obtained in Examples 1-4 and Comparative Examples 1-5 were detected using a gas chromatography-mass spectrometry method. The detection results are shown in Table 1.

[0115] Table 1 Distribution of bio-oil components

[0116] It can be found from Examples 1 to 4 and Comparative Examples 1 to 5 that the pretreated biomass classification-nitrogen-enriched pyrolysis process significantly improves the distribution of pyridine compounds in bio-oil. The specific reasons are: (1) Acid washing / alkaline washing / oxidation pretreatment significantly reduced the content of alkali metals and alkaline earth metals, and promoted the production of ketones and dehydrated sugar compounds by destroying the chemical cross-linking of cellulose and lignin. It also promoted the production of pyridines, amines and imidazoles under nitrogen-rich conditions, thereby reducing the complexity of bio-oil.

[0117] (2) During the graded pyrolysis process, a mesoporous molecular sieve catalyst modified with metal oxides was added for in situ catalysis. The direct contact between the catalyst and the biomass enhanced the heat transfer and promoted the thermal cracking of the biomass. The metal oxides significantly promoted the conversion of biomass (especially cellulose and hemicellulose components) into small molecular carbonyl compounds.

[0118] (3) In the process of directed aldehyde ketonization, bimetallic MOF-based catalysts are added for heterogeneous catalysis, which can more accurately regulate the conversion of easily aldehyde ketonized components such as dehydrated sugars, acids, and alcohols into aldehyde ketonate components, improve the selectivity of the target product, and reduce the influence of the raw materials on the carbon deposition and deactivation of the catalyst.

[0119] (4) The oxygen-free atmosphere can change the decomposition pathway of some oxygen-containing compounds in bio-oil, promote the formation of ketones, esters and sugar compounds, and thus provide sufficient intermediates for pyridine compounds. Under nitrogen-rich conditions, aldehyde-rich ketone components and NH3 are converted into pyridine compounds through the Maillard reaction. The higher the NH3 concentration, the higher the selectivity of pyridine compounds. By changing the pyrolysis atmosphere, the distribution of aldehyde-rich ketone components and pyridines can also be improved.

Claims

1. A production process for preparing pyridine-rich bio-oil by pre-treated biomass classification-nitrogen-rich pyrolysis, Features: It consists of the following steps: (1) First, the biomass is crushed and sieved to obtain biomass powder, and then the biomass powder is added to a washing solution for pretreatment, and then filtered, washed, and dried to obtain pretreated biomass; (2) dispersing the mesoporous molecular sieve in deionized water, then adding a first metal salt solution, stirring, drying, and calcining to prepare a metal oxide-modified mesoporous molecular sieve catalyst; (3) dispersing MOF in deionized water, then adding a second metal salt solution, stirring, drying, and calcining to prepare a bimetallic supported MOF-based catalyst; (4) the pretreated biomass prepared in step (1) and the metal oxide-modified mesoporous molecular sieve catalyst prepared in step (2) are mixed evenly and added to a first pyrolysis reactor, and graded pyrolysis is performed in an oxygen-free atmosphere to obtain first aldehyde- and ketone-rich pyrolysis steam, aldehyde- and ketone-prone pyrolysis steam, and aldehyde- and ketone-prone pyrolysis steam in different temperature ranges; (5) passing the first aldehyde- and ketone-rich pyrolysis steam in step (4) into a second pyrolysis reactor to perform nitrogen-rich pyrolysis under ammonia conditions, and passing the volatile matter into a No. 1 condenser to condense and obtain a first pyridine-rich bio-oil; (6) passing the aldehyde-ketonization pyrolysis steam in step (4) into a catalytic reactor loaded with the bimetallic-supported MOF-based catalyst prepared in step (3), and performing an ex situ catalytic online aldehyde-ketonization reaction on the aldehyde-ketonization pyrolysis steam to obtain a second aldehyde- and ketone-rich pyrolysis steam; (7) passing the second aldehyde- and ketone-rich pyrolysis steam in step (6) into a third pyrolysis reactor to perform nitrogen-rich pyrolysis under ammonia conditions, and passing the volatile matter into a No. 2 condenser to condense and obtain a second pyridine-rich bio-oil; (8) The pyrolysis steam that is not easily aldehyde-ketone-prone in step (4) is passed into condenser No. 3 to condense and obtain bio-oil.

2. The production process for preparing pyridine-rich bio-oil by pretreated biomass classification-nitrogen-rich pyrolysis according to claim 1, Features: The biomass in step (1) refers to one or a mixture of wood, crop straw, fruit shells, leaves, bark, food processing residues or model compounds; The wood is one or more of pine, poplar or camphor; the crop straw is one or more of corn straw, cotton straw or wheat straw; the fruit shell is one or more of coconut shell, grapefruit peel or walnut shell; the model compound is one or more of cellulose, glucose, xylose, xylan, alkali lignin, aldehyde or ketone; The particle size of the biomass powder in step (1) is 40-100 mesh.

3. The production process for preparing pyridine-rich bio-oil by pretreated biomass classification-nitrogen-rich pyrolysis according to claim 1, Features: The washing solution in step (1) is one of an acidic solution, an alkaline solution or an oxidizing solution, wherein the acidic solution is a mixture of one of acetic acid, formic acid, oxalic acid or propionic acid and deionized water, and the concentration of the acidic solution is 1-10 mol / L; the alkaline solution is a sodium hydroxide solution, and the concentration is 1-10 mol / L; the oxidizing solution is a hydrogen peroxide solution, and the concentration is 1-10 mol / L; The mass volume ratio of the biomass powder to the washing solution in step (1) is 1:25-75, in g / mL; In step (1), the biomass powder is immersed in the prepared washing solution and stirred for 1-5 hours at 20-40° C. using a constant temperature magnetic rotor stirrer for pretreatment. The pretreated raw material is repeatedly washed with deionized water until the pH value of the water filtered out for the last time is 7±0.03, and then the filter residue is dried at 80-200° C. for 8-48 hours to obtain the pretreated biomass.

4. The production process for preparing pyridine-rich bio-oil by pretreated biomass classification-nitrogen-rich pyrolysis according to claim 1, Features: The mesoporous molecular sieve in step (2) refers to one or more of the M41S series, MSU series or SBA series, the M41S series is one of the MCM-41 mesoporous molecular sieve, MCM-22 mesoporous molecular sieve, MCM-48 mesoporous molecular sieve or MCM-50 mesoporous molecular sieve, the MSU series is the MSU-1 mesoporous molecular sieve, and the SBA series is one of the SBA-15 mesoporous molecular sieve or SBA-16 mesoporous molecular sieve; In step (2), the mass ratio of the mesoporous molecular sieve to deionized water is 1:1-3; In step (2), the first metal salt solution is Co (NO 3 ) 2 6H 2 O, Ni (NO 3 ) 2 6H 2 O、Zr(NO 3 ) 4 10H 2 O、Ce(NO 3 ) 3 6H 2 O、Mn(NO 3 ) 2 ·4H 2 O or Mg (NO 3 ) 2 6H 2 O is mixed with deionized water to obtain a solution, wherein the concentration of the first metal salt solution is 0.1-5 mol / L; The metal loading in the metal oxide-modified mesoporous molecular sieve catalyst in step (2) is 5-30wt%; In step (2), a constant temperature magnetic rotor stirrer is used to stir the mixture of the mesoporous molecular sieve and deionized water and the first metal salt solution at 20-60° C. for 1-12 h, then dry at 80-200° C. for 8-24 h, and finally calcine at 500-800° C. for 4-12 h to prepare a metal oxide modified mesoporous molecular sieve catalyst.

5. The production process for preparing pyridine-rich bio-oil by pretreated biomass classification-nitrogen-rich pyrolysis according to claim 1, Features: The MOF in step (3) refers to one or more of a mesh metal-organic framework series material, a zeolite imidazolate framework series material, a pore-channel framework series material or a Lavahill framework series material; Among them, the mesh metal-organic framework series material is one of IRMOFs-1, IRMOFs-3, IRMOFs-6 or IRMOFs-8; the zeolite imidazolate framework series material is one of ZIF-8, ZIF-11 or ZIF-67; the pore-channel framework series material is one of PCN-9, PCN-14 or PCN-53; the Lavahill framework series material is one of MIL-53, MIL-100 or MIL-101; In step (3), MOF is dispersed in deionized water, and the mass ratio of MOF to deionized water is 1:1-3.

6. The production process for preparing pyridine-rich bio-oil by pretreated biomass classification-nitrogen-rich pyrolysis according to claim 1, Features: In step (3), the second metal salt solution is Ce(NO 3 ) 3 、RuCl 3 、Co(NO 3 ) 2 ,Ni(NO 3 ) 2 、Zr(NO 3 ) 4 、Mn(NO 3 ) 2 or Mg(NO 3 ) 2 A solution obtained by mixing any two of the above with deionized water, wherein the concentration of the second metal salt solution is 0.1-2 mol / L; The metal loading in the bimetallic MOF-based catalyst in step (3) is 5-30 wt %, and the loading of the two metals is the same; In step (3), a constant temperature magnetic rotor stirrer is used to stir the mixture of MOF and deionized water and the second metal salt solution at 20-60° C. for 1-12 h, then dry at 80-200° C. for 8-24 h, and finally calcine at 500-800° C. for 4-12 h to prepare a bimetallic supported MOF-based catalyst.

7. The production process for preparing pyridine-rich bio-oil by pretreated biomass classification-nitrogen-rich pyrolysis according to claim 1, Features: In step (4), the mass ratio of the pretreated biomass to the metal oxide modified mesoporous molecular sieve catalyst is 1:1-5; The oxygen-free atmosphere in step (4) refers to nitrogen, argon, helium, CO 2 or a mixture of one or more of CO, with a gas flow rate of 100-200 mL / min; The graded pyrolysis described in step (4) is to set multiple temperature intervals within 20-800°C, the insulation time of each temperature interval is 3s-30min, and the pyrolysis heating rate is 2-15°C / min.

8. The production process for preparing pyridine-rich bio-oil by pretreated biomass classification-nitrogen-rich pyrolysis according to claim 1, Features: The second pyrolysis reactor in step (5) is heated and kept warm synchronously with the first pyrolysis reactor in step (4), and the pyrolysis temperature range, pyrolysis heating rate, holding time and gas flow rate of the nitrogen-rich pyrolysis under ammonia conditions are consistent with the reaction conditions when the first aldehyde-rich ketone pyrolysis steam is obtained in the first pyrolysis reactor in step (4); The ammonia condition in step (5) refers to the carrier gas being pure NH 3 or NH 3 A mixture of gas with other inert gases, wherein the other inert gas is one of argon or nitrogen; The mass of the bimetallic supported MOF-based catalyst in step (6) is 1-5 times the mass of the pretreated biomass; The catalytic reactor in step (6) is heated and kept warm synchronously with the first pyrolysis reactor in step (4), and the temperature range, heating rate, holding time and gas flow rate of the heterogeneous catalytic online aldehyde-ketonization reaction are consistent with the reaction conditions when the aldehyde-ketonization pyrolysis steam is obtained in the first pyrolysis reactor in step (4); The catalytic reactor in step (6) is an oxygen-free atmosphere, and the gas type is consistent with the oxygen-free atmosphere in step (4).

9. The production process for preparing pyridine-rich bio-oil by pretreated biomass classification-nitrogen-rich pyrolysis according to claim 1, Features: The ammonia condition in step (7) refers to the carrier gas being pure NH 3 or NH 3 A mixture of gas with other inert gases, wherein the other inert gas is one of argon or nitrogen; The third pyrolysis reactor in step (7) is heated and kept warm synchronously with the first pyrolysis reactor in step (4), and the pyrolysis temperature range, pyrolysis heating rate, holding time and gas flow rate of nitrogen-rich pyrolysis under ammonia conditions are consistent with the reaction conditions when the pyrolysis steam easily aldehyde-ketonized is obtained in the first pyrolysis reactor in step (4).

10. The production process for preparing pyridine-rich bio-oil by pretreated biomass classification-nitrogen-rich pyrolysis according to claim 1, Features: The condensation temperature of the No. 1 condenser in step (5), the No. 2 condenser in step (7) and the No. 3 condenser in step (8) is -30-30°C.

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