阅读说明：本技术 杨木催化热裂解制取富含单环芳烃生物油的实现方法 (Method for preparing monocyclic aromatic hydrocarbon-rich bio-oil by catalytic thermal cracking of poplar ) 是由 刘荣厚 李英凯 李冲 朱献濮 于 2021-08-03 设计创作，主要内容包括：一种杨木催化热裂解制取富含单环芳烃生物油的实现方法,采用NaOH溶液对ZSM-5分子筛进行脱硅处理,得到多级孔ZSM-5分子筛；将得到的多级孔ZSM-5分子筛以浸渍法与Fe(NO-(3))-(3)溶液混合制备得到Fe负载多级孔ZSM-5分子筛,改善催化剂的催化性能；最后,将Fe负载多级孔ZSM-5分子筛和杨木木屑进行混合,进行快速催化热裂解反应实现富含单环芳烃生物油的制取,提高生物质催化快速热裂解生物油中单环芳烃的相对含量,提高生物油的应用价值。(A method for preparing bio-oil rich in monocyclic aromatic hydrocarbon by catalytic thermal cracking of poplar adopts NaOH solution to carry out desiliconization treatment on a ZSM-5 molecular sieve to obtain a hierarchical pore ZSM-5 molecular sieve; mixing the obtained hierarchical pore ZSM-5 molecular sieve with Fe (NO) by an impregnation method 3 ) 3 The solution is mixed to prepare a Fe-loaded hierarchical pore ZSM-5 molecular sieve, so that the catalytic performance of the catalyst is improved; finally, mixing the Fe-loaded multistage-hole ZSM-5 molecular sieve with the poplar wood chips, performing rapid catalytic pyrolysis reaction to prepare the bio-oil rich in the monocyclic aromatic hydrocarbon, and improving the catalytic rapid pyrolysis of the biomassThe relative content of monocyclic aromatic hydrocarbon in the biological oil improves the application value of the biological oil.)

1. Poplar woodThe catalytic pyrolysis method for preparing the biological oil rich in the monocyclic aromatic hydrocarbon is characterized in that a ZSM-5 molecular sieve is subjected to desiliconization treatment by adopting a NaOH solution to obtain a hierarchical pore ZSM-5 molecular sieve; mixing the obtained hierarchical pore ZSM-5 molecular sieve with Fe (NO) by an impregnation method₃)₃Mixing the solutions to prepare a Fe-loaded hierarchical pore ZSM-5 molecular sieve; and finally, mixing the Fe-loaded multistage-hole ZSM-5 molecular sieve with the poplar wood chips, and carrying out rapid catalytic thermal cracking reaction to prepare the bio-oil rich in the monocyclic aromatic hydrocarbon.

2. The method as claimed in claim 1, wherein the ZSM-5 molecular sieve is commercial ZSM-5 with a silica/alumina ratio of 25.

3. The method as claimed in claim 1, wherein the ZSM-5 molecular sieve with multi-stage pores is prepared by mixing 0.4mol/L NaOH solution with the ZSM-5 molecular sieve, heating, stirring for 2 hr, adding into ice water mixture, filtering, drying, and passing through NH₄And carrying out ion exchange treatment on the Cl solution, and finally calcining to obtain the multistage-pore ZSM-5 molecular sieve.

4. The method as claimed in claim 1, wherein the calcining temperature is 550 ℃ and the calcining time is 5 hours.

5. The method for preparing the bio-oil rich in the monocyclic aromatic hydrocarbon through the catalytic thermal cracking of the poplar as claimed in claim 1, wherein the impregnation method comprises the following steps: slowly adding the multi-stage hole ZSM-5 molecular sieve into Fe (NO)₃)₃And (3) keeping stirring in the solution until a paste is formed, drying and roasting to obtain the Fe-loaded hierarchical porous ZSM-5 molecular sieve.

6. The method for preparing the bio-oil rich in the monocyclic aromatic hydrocarbons through the catalytic thermal cracking of the poplar as claimed in claim 1, wherein the impregnation method is characterized in that the Fe loading is 2, 4, 6 or 8 wt.%.

7. The method as claimed in claim 1, wherein the Fe-supported multi-stage pore ZSM-5 molecular sieve catalyst is ground into powder and sieved to a particle size of 80 mesh.

8. The method for preparing the bio-oil rich in the monocyclic aromatic hydrocarbon through the catalytic thermal cracking of the poplar as claimed in claim 1, wherein the step of mixing the Fe-loaded hierarchical-pore ZSM-5 molecular sieve catalyst with the poplar wood chips is as follows: mixing a catalyst and poplar wood chips in a mass ratio of 1: 1, mixing.

9. The method for preparing the bio-oil rich in the monocyclic aromatic hydrocarbon through the catalytic thermal cracking of the poplar as claimed in claim 1, wherein the rapid catalytic thermal cracking reaction is as follows: in the process of biomass rapid thermal cracking, a catalyst is added to improve the quality of thermal cracking steam, so that the thermal cracking steam is subjected to catalytic conversion by the catalyst to obtain high-quality liquid fuel or chemicals.

Technical Field

The invention relates to a technology in the field of renewable biomass energy sources, in particular to a realization method for preparing monocyclic aromatic hydrocarbon-rich bio-oil by catalytic thermal cracking of poplar.

Background

The poplar has the characteristics of abundant reserves, environmental friendliness and reproducibility. The biomass thermal cracking technology can convert the biomass into liquid fuel (bio-oil), and is a thermochemical conversion technology with wide application prospect. However, because of the disadvantages of complex components, high oxygen content, strong acidity, low calorific value, etc., the bio-oil has limited industrial application, and the quality of the bio-oil is urgently needed to be improved.

In the thermal cracking process, a specific reaction path can be enhanced by adding a proper catalyst, and the formation of an ideal product is promoted, so that the quality of the bio-oil is effectively improved. Among various catalysts, ZSM-5 molecular sieves have received much attention in catalytic thermal cracking of biomass due to their good acidity and selectivity, as well as their good deoxygenation and aromatization properties. However, due to the limitation of the pore size of the ZSM-5 molecular sieve, the conventional ZSM-5 molecular sieve has diffusion limitation on macromolecules, and the catalytic activity is reduced.

Aiming at the problems, the ZSM-5 is subjected to alkali solution desilication treatment, so that a hierarchical pore structure can be introduced into a ZSM-5 molecular sieve, and the catalytic performance of the catalyst is improved. Meanwhile, aiming at the problems of complex components and high oxygen content of the bio-oil, the acid sites and the physicochemical properties of the catalyst can be adjusted by introducing metal into the ZSM-5 molecular sieve, the composition of the bio-oil is improved, and the relative content of monocyclic aromatic hydrocarbon in the bio-oil subjected to catalytic thermal cracking of the biomass is increased.

Therefore, the ZSM-5 molecular sieve is treated by combining alkali solution desilication treatment and metal loading, the advantages of the alkali solution desilication treatment and the metal loading can be combined, the catalytic performance of the catalyst is improved, the relative content of monocyclic aromatic hydrocarbon in the biomass catalytic rapid thermal cracking biological oil is increased, and the application value of the biological oil is increased.

Disclosure of Invention

Aiming at the defects in the prior art, the invention provides a method for preparing the bio-oil rich in the monocyclic aromatic hydrocarbon by catalytic pyrolysis of poplar, which adopts a mode of combining alkali solution desilication and metal loading, a ZSM-5 molecular sieve obtains a hierarchical pore ZSM-5 molecular sieve by alkali solution desilication, and the hierarchical pore ZSM-5 molecular sieve is loaded with 2, 4, 6 and 8 wt.% of Fe metal on the basis of the hierarchical pore molecular sieve to prepare the Fe-loaded hierarchical pore ZSM-5 molecular sieve. The molecular sieve is utilized to carry out rapid catalytic thermal cracking on poplar wood chips to prepare the bio-oil rich in monocyclic aromatic hydrocarbon.

The invention is realized by the following technical scheme:

the invention relates to a method for preparing monocyclic aromatic hydrocarbon-rich bio-oil by catalytic pyrolysis of poplar, which comprises the steps of carrying out desiliconization treatment on a ZSM-5 molecular sieve by adopting a NaOH solution to obtain a hierarchical-pore ZSM-5 molecular sieve; mixing the obtained hierarchical pore ZSM-5 molecular sieve with Fe (NO) by an impregnation method₃)₃Mixing the solutions to prepare a Fe-loaded hierarchical pore ZSM-5 molecular sieve; and finally, mixing the Fe-loaded multistage-hole ZSM-5 molecular sieve with the poplar wood chips, and carrying out rapid catalytic thermal cracking reaction to prepare the bio-oil rich in the monocyclic aromatic hydrocarbon.

The ZSM-5 molecular sieve is preferably commercial ZSM-5 with a silica-alumina ratio of 25.

The multi-stage pore ZSM-5 molecular sieve is prepared by heating and stirring 0.4mol/L NaOH solution and the ZSM-5 molecular sieve for 2 hours, placing the mixture in an ice-water mixture, filtering and drying the mixture, and passing the mixture through NH₄And carrying out ion exchange treatment on the Cl solution, and finally calcining to obtain the multistage-pore ZSM-5 molecular sieve.

The calcination is preferably carried out at 550 ℃ for 5 hours.

The impregnation method comprises the following steps: slowly adding the multi-stage hole ZSM-5 molecular sieve into Fe (NO)₃)₃And (3) keeping stirring in the solution until a paste is formed, drying and roasting to obtain the Fe-loaded hierarchical porous ZSM-5 molecular sieve.

The impregnation method has Fe loading of 2, 4, 6 and 8 wt.%.

The Fe-supported hierarchical-pore ZSM-5 molecular sieve catalyst is preferably ground into powder and sieved until the particle size is 80 meshes.

The mixing of the Fe-loaded hierarchical-pore ZSM-5 molecular sieve catalyst and the poplar wood chips refers to the following steps: mixing a catalyst and poplar wood chips in a mass ratio of 1: 1, mixing.

The rapid catalytic thermal cracking reaction is as follows: in the process of biomass rapid thermal cracking, a catalyst is added to improve the quality of thermal cracking steam, so that the thermal cracking steam is subjected to catalytic conversion by the catalyst to obtain high-quality liquid fuel or chemicals.

Technical effects

The invention integrally solves the problems that in the process of preparing the bio-oil by catalytic thermal cracking of the ZSM-5 molecular sieve catalyst in the prior art, the catalyst has diffusion limitation on macromolecules, so that the catalytic activity is reduced, the prepared bio-oil has poor quality, the content of monocyclic aromatic hydrocarbon is low and the like.

Drawings

FIG. 1 is a diagram of an Fe-supported hierarchical pore molecular sieve prepared according to the present invention;

in the figure: P-ZSM-5 as parent catalyst; Hie-ZSM-5 is a hierarchical pore molecular sieve after desiliconization treatment;

fe (x) -Hie-ZSM-5 respectively represents a hierarchical pore molecular sieve with Fe loading of xwt.%;

FIG. 2 is the results of characterization of the catalyst of example 1;

in the figure: (a) XRD spectrogram; (b) n is a radical of₂Adsorption-desorption curves; (c) TEM pictures; (d) NH (NH)₃-a TPD spectrum;

FIG. 3 is a schematic diagram of the effect of different Fe-supported hierarchical pore ZSM-5 molecular sieve catalysts on the level of monocyclic aromatics;

in the figure: (1) is a parent catalyst; (2) is a multistage pore molecular sieve after desiliconization treatment; (3) - (6) multistage pore ZSM-5 molecular sieves with Fe loadings of 2, 4, 6 and 8 wt.%, respectively.

Detailed Description

Example 1

The embodiment relates to a realization method for preparing bio-oil rich in monocyclic aromatic hydrocarbon by catalytic thermal cracking of poplar, which comprises the following steps:

firstly, selecting a commercial ZSM-5 catalyst with a silicon-aluminum ratio of 25 as a parent catalyst, calcining the parent catalyst at 550 ℃ for 5 hours, grinding and sieving to ensure that the particle size is 0.25-0.85 mm.

Secondly, carrying out desiliconization treatment on the ZSM-5 catalyst by adopting 0.4mol/L NaOH solution, and the specific process comprises the following steps: 35g of ZSM-5 was mixed with 350mL of 0.4mol/L NaOH solution at 70 ℃ for 2 hours. The reaction mixture was put in an ice-water mixture to terminate the reaction, filtered, washed 3 times with deionized water, and then dried at 105 ℃ overnight. Finally, with 1mol/L NH₄The Cl solution was ion-exchanged at 80 ℃ for 8 hours and then washed three times with deionized water. Drying at 105 ℃ for 2 hours, and roasting at 550 ℃ for 5 hours to prepare the hierarchical pore ZSM-5 molecular sieve catalyst.

And thirdly, preparing the Fe-loaded hierarchical pore ZSM-5 molecular sieve catalyst with Fe loading amounts of 2, 4, 6 and 8 wt.% by adopting an impregnation method for the hierarchical pore ZSM-5 molecular sieve catalyst. The specific process is as follows: 5g of multi-stage pore ZSM-5 molecular sieve catalyst was slowly added to approximately 15mL of ferric nitrate solution with a Fe loading of 2 wt.%. The mixed solution was stirred at 40 ℃ until a paste was formed. The stirred mixture was then dried at 105 ℃ overnight and finally the dried mixture was calcined in a 550 ℃ muffle furnace for 5 hours. The catalyst was ground to a powder and sieved to a particle size of 80 mesh.

The catalyst prepared in this example, after 0.4mol/L NaOH desilication treatment and 2, 4, 6 and 8 wt.% Fe metal loading, formed a hierarchical pore structure in the ZSM-5 molecular sieve and improved its acidity and strongly acidic sites.

Fourthly, mixing the catalyst and the poplar wood chips according to a mass ratio of 1: 1, and preparing the bio-oil steam rich in monocyclic aromatic hydrocarbon by a thermal cracking-gas chromatography-mass spectrometer, wherein the relative content of monocyclic aromatic hydrocarbon in the prepared fast catalytic thermal cracking bio-oil steam is 14.84%.

An EGA/PY-3030D FrontierLab pyrolysis instrument and Agilent 7890B/5977B gas chromatography/mass spectrometry are combined to perform a poplar sawdust rapid catalytic pyrolysis test. In this study, the thermal cracking test was conducted at 550 ℃ in an ionization mode of electron impact ion source (EI) using high purity nitrogen (99.999%) as a carrier gas at a flow rate of 3 mL/min. The programmed temperature conditions of the GC oven box are as follows: the initial value was 40 ℃, held for 2 minutes, then ramped up to 200 ℃ at 5 ℃/min, ramped up to 300 ℃ at 20 ℃/min, and held for 11 minutes.

The surface area and pore structure of the Fe-supported hierarchical pore ZSM-5 molecular sieve catalyst obtained by the NaOH desilication treatment and Fe metal loading are shown in table 1.

TABLE 1 surface area and pore Structure of ZSM-5 molecular sieves

Example 2

The embodiment relates to a method for preparing bio-oil with monocyclic aromatic content by catalytic thermal cracking of poplar, which comprises the following steps:

firstly, selecting a commercial ZSM-5 catalyst with a silicon-aluminum ratio of 25 as a parent catalyst, calcining the parent catalyst at 550 ℃ for 5 hours, grinding and sieving to ensure that the particle size is 0.25-0.85 mm.

Secondly, adopting 0.4mol/L NaOH solution to carry out desiliconization treatment on the ZSM-5, and the specific process is as follows: 35g of ZSM-5 was mixed with 350mL of 0.4mol/L NaOH solution at 70 ℃ for 2 hours. The reaction mixture was put in an ice-water mixture to terminate the reaction, filtered, washed 3 times with deionized water, and then dried at 105 ℃ overnight. Finally, with 1mol/L NH₄The Cl solution was ion-exchanged at 80 ℃ for 8 hours and then washed three times with deionized water. Drying at 105 ℃ for 2 hours, and roasting at 550 ℃ for 5 hours to prepare the hierarchical pore ZSM-5 molecular sieve catalyst.

Thirdly, preparing the catalyst with Fe loading capacity of 2, 4, 6 and 8 wt.% by adopting a multistage pore ZSM-5 molecular sieve catalyst by adopting an impregnation method, wherein the specific process comprises the following steps: 5g of multi-stage pore ZSM-5 was slowly added to approximately 15mL of ferric nitrate solution with a Fe loading of 4 wt.%. The mixed solution was stirred at 40 ℃ until a paste was formed. The stirred mixture was then dried at 105 ℃ overnight and finally the dried mixture was calcined in a 550 ℃ muffle furnace for 5 hours. The catalyst was ground to a powder and sieved to a particle size of 80 mesh.

Fourthly, mixing the catalyst and the poplar wood chips according to a mass ratio of 1: 1, preparing the bio-oil steam rich in monocyclic aromatic hydrocarbon by a thermal cracking-gas chromatography-mass spectrometer, wherein the relative content of monocyclic aromatic hydrocarbon in the prepared fast catalytic thermal cracking bio-oil steam is 15.30%.

Example 3

The embodiment relates to a method for preparing bio-oil with monocyclic aromatic content by catalytic thermal cracking of poplar, which comprises the following steps:

firstly, selecting a commercial ZSM-5 catalyst with a silicon-aluminum ratio of 25 as a parent catalyst, calcining the parent catalyst at 550 ℃ for 5 hours, grinding and sieving to ensure that the particle size is 0.25-0.85 mm.

Secondly, adopting 0.4mol/L NaOH solution to carry out desiliconization treatment on the ZSM-5, and the specific process is as follows: 35g of ZSM-5 was mixed with 350mL of 0.4mol/L NaOH solution at 70 ℃ for 2 hours. The reaction mixture was put in an ice-water mixture to terminate the reaction, filtered, washed 3 times with deionized water, and then dried at 105 ℃ overnight. Finally, with 1mol/L NH₄The Cl solution was ion-exchanged at 80 ℃ for 8 hours and then washed three times with deionized water. Drying at 105 ℃ for 2 hours, and roasting at 550 ℃ for 5 hours to prepare the hierarchical pore ZSM-5 molecular sieve.

Thirdly, preparing the catalyst with Fe loading capacity of 2, 4, 6 and 8 wt.% by adopting a multi-stage pore ZSM-5 impregnation method, which comprises the following specific steps: 5g of multi-stage pore ZSM-5 was slowly added to approximately 15mL of ferric nitrate solution with a Fe loading of 6 wt.%. The mixed solution was stirred at 40 ℃ until a paste was formed. The stirred mixture was then dried at 105 ℃ overnight and finally the dried mixture was calcined in a 550 ℃ muffle furnace for 5 hours. The catalyst was ground to a powder and sieved to a particle size of 80 mesh.

Fourthly, mixing the catalyst and the poplar wood chips according to a mass ratio of 1: 1, preparing the bio-oil steam rich in monocyclic aromatic hydrocarbon by a thermal cracking-gas chromatography-mass spectrometer, wherein the relative content of monocyclic aromatic hydrocarbon in the prepared fast catalytic thermal cracking bio-oil steam is 13.06%.

Example 4

The embodiment relates to a method for preparing bio-oil with monocyclic aromatic hydrocarbon content by catalytic thermal cracking of poplar, which comprises the following steps:

firstly, selecting a commercial ZSM-5 catalyst with a silicon-aluminum ratio of 25 as a parent catalyst, calcining the parent catalyst at 550 ℃ for 5 hours, grinding and sieving to ensure that the particle size is 0.25-0.85 mm.

Secondly, adopting 0.4mol/L NaOH solution to carry out desiliconization treatment on the ZSM-5, and the specific process is as follows: 35g of ZSM-5 was mixed with 350mL of 0.4mol/L NaOH solution at 70 ℃ for 2 hours. The reaction mixture was put in an ice-water mixture to terminate the reaction, filtered, washed 3 times with deionized water, and then dried at 105 ℃ overnight. Finally, with 1mol/L NH₄The Cl solution was ion-exchanged at 80 ℃ for 8 hours and then washed three times with deionized water. Drying at 105 ℃ for 2 hours, and roasting at 550 ℃ for 5 hours to prepare the hierarchical pore ZSM-5 molecular sieve.

Thirdly, preparing the catalyst with Fe loading capacity of 2, 4, 6 and 8 wt.% by adopting a multi-stage pore ZSM-5 impregnation method, which comprises the following specific steps: 5g of multi-stage pore ZSM-5 was slowly added to approximately 15mL of ferric nitrate solution with an Fe loading of 8 wt.%. The mixed solution was stirred at 40 ℃ until a paste was formed. The stirred mixture was then dried at 105 ℃ overnight and finally the dried mixture was calcined in a 550 ℃ muffle furnace for 5 hours. The catalyst was ground to a powder and sieved to a particle size of 80 mesh.

Fourthly, mixing the catalyst and the poplar wood chips according to a mass ratio of 1: 1, mixing the raw materials, and preparing the bio-oil steam rich in monocyclic aromatic hydrocarbon by a thermal cracking-gas chromatography-mass spectrometer, wherein the relative content of monocyclic aromatic hydrocarbon in the prepared fast catalytic thermal cracking bio-oil steam is 13.31%.

The foregoing embodiments may be modified in many different ways by those skilled in the art without departing from the spirit and scope of the invention, which is defined by the appended claims and all changes that come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.