WO2018161280A1

WO2018161280A1 - Method for preparing 4-ethylphenol by catalytic pyrolysis of bagasse with activated carbon

Info

Publication number: WO2018161280A1
Application number: PCT/CN2017/075988
Authority: WO
Inventors: 陆强; 叶小宁; 王昕�; 郭浩强; 周民星; 董长青; 杨勇平
Original assignee: 华北电力大学
Priority date: 2017-03-06
Filing date: 2017-03-08
Publication date: 2018-09-13
Also published as: CN106946658B; CN106946658A

Abstract

The present invention pertains to the field of utilization of biomass energy, and in particular relates to a method for preparing 4-ethylphenol by catalytic pyrolysis of bagasse with activated carbon. The present invention uses bagasse as a raw material and activated carbon as a catalyst. The activated carbon is prepared from biomass using a steam activation method. The bagasse is mechanically mixed with the activated carbon and then catalytically pyrolyzed in a hydrogen atmosphere at 240-410°C, and a liquid product rich in 4-ethylphenol can be obtained after condensing the pyrolysis gas. The yield of 4-ethylphenol and its purity in the liquid product are both high. In addition, the method of the present invention uses bagasse having a wide range of sources as a raw material and inexpensive activated carbon as a catalyst, making it possible to significantly reduce the production costs of 4-ethylphenol.

Description

Method for preparing 4-ethylphenol by activated carbon catalyzed pyrolysis of bagasse

Technical field

The invention belongs to the field of utilization of biomass energy, and particularly relates to a method for preparing 4-ethylphenol by catalytically pyrolyzing bagasse of activated carbon.

Background technique

4-ethylphenol is a colorless needle crystal with special odor. It is widely used as a raw material for phenolic resin, rubber anti-aging agent, plastic anti-aging agent, surfactant, nonionic emulsifier, synthetic fragrance and pesticide. , edible flavors, organic synthetic intermediates and chemical reagents. Although the preparation method of 4-ethylphenol is disclosed in Chinese Patent Application No. 201010123979.3, the raw materials are not extensive, so that the economics of preparing 4-ethylphenol is difficult to ensure.

As an important biomass resource, bagasse is an environmentally friendly renewable resource. Bagasse can produce more 4-vinyl phenol in the conventional low-temperature pyrolysis process. Chinese patent application 201110134872.3 discloses this technology; and 4-ethylphenol as a hydrogenation product of 4-vinyl phenol in conventional biomass The content of the pyrolysis liquid product is extremely small (not more than 1%), which makes it difficult to prepare 4-ethylphenol directly by thermal decomposition of bagasse. In order to increase the yield of 4-ethylphenol, it is necessary to realize the on-line hydrogenation of 4-vinylphenol and its precursors while pyrolyzing the precursor of 4-vinylphenol to form 4-vinylphenol. 4-ethylphenol was obtained. The most effective way to achieve this is to introduce a suitable catalyst to promote the catalytic pyrolysis of bagasse directly to form 4-ethylphenol instead of 4-vinylphenol. Chinese patent application 201410558325.1 reports the preparation of 4-ethylphenol by catalytic pyrolysis of biomass using a palladium-based precious metal catalyst. The palladium-based precious metal catalyst is expensive and difficult to be practically applied, thereby greatly limiting the industrial application of the technology.

In addition, Lu Qiang et al. (Catalytic fast pyrolysis of bagasse using activated carbon catalyst to selective produce 4-ethyl Phenol, Energy & Fuels, 2016, 30, 10618-10626) reported for the first time that activated carbon was used as a catalyst to catalytically pyrolyze bagasse under nitrogen atmosphere to prepare 4-ethylphenol, although activated carbon showed some catalysis. Hydrogenation activity, but the yield of 4-ethylphenol based on this process is lower, the yield is only 2.49%; and the selectivity in organic liquid products is only 10.71%. Therefore, a novel preparation method of 4-ethylphenol is provided, and the production of environmentally friendly, low-cost, high-efficiency 4-ethylphenol has become a priority.

Summary of the invention

The object of the present invention is to overcome the deficiencies of the prior art and to provide a method for preparing 4-ethylphenol by catalytically pyrolyzing bagasse with activated carbon.

According to the method provided by the present invention, bagasse is used as a raw material, activated carbon is used as a catalyst, and bagasse and activated carbon catalyst are mechanically mixed according to a mass ratio of (10:1) to (1:5), and then in a hydrogen atmosphere at 240~. Rapid pyrolysis at 410 ° C, the pyrolysis reaction time is less than 50 s, the condensation of the pyrolysis gas can obtain a liquid product rich in 4-ethylphenol.

Preferably, the activated carbon catalyst is activated carbon prepared by the steam activation method of biomass, and the specific preparation method is as follows:

The biomass material is crushed to a particle size of 1 mm, first carbonized and cooled in an inert atmosphere; the carbonized material is activated under a water vapor atmosphere; and activated carbon is obtained after cooling.

The carbonization process has a heating rate of 5 to 20 ° C / min, a carbonization temperature of 300 to 500 ° C, and a carbonization time of 0.5 to 2 h.

The activation process of the activated carbon preparation has a heating rate of 15 to 50 ° C / min, an activation temperature of 700 to 1000 ° C, and an activation time of 1.5 to 3 h.

The water vapor atmosphere prepared by the activated carbon is a mixture of water vapor and an inert oxygen-free protective gas in the reaction system.

The biomass feedstock prepared from the activated carbon is lignocellulosic biomass, including but not limited to wood, crop straw, bamboo or herbaceous biomass.

The bagasse is fruit bagasse or sugar cane bagasse or a mixture of the two.

The hydrogen atmosphere is a mixture of hydrogen and an inert oxygen-free protective gas in the reaction system.

Preferably, the concentration of hydrogen in the mixed gas is 2 to 14 vol%.

The rate of temperature rise of the pyrolysis reaction is higher than 100 ° C / s.

The pyrolysis reaction takes less than 50 seconds.

The beneficial effects of the invention are:

The invention uses a biomass-based steam activated carbon as a catalyst to prepare a liquid product rich in 4-ethylphenol by catalytic pyrolysis of bagasse under a hydrogen atmosphere. Activated carbon is a widely used carbon-based material, and steam activation is a common method for physically preparing activated carbon. Therefore, the catalyst selected for the present invention is commonly available and low in cost; moreover, the activated carbon selected by the present invention is made of biomass. The raw materials are prepared, so they are also environmentally friendly and environmentally friendly, and have obvious advantages over precious metal-based hydrogenation catalysts. The activated carbon catalyst obtained by the steam activation method has a greatly reduced oxygen content, is weakly alkaline, and has a large amount of oxygen-free functional groups such as CC, CH, and C=C on the surface, and can provide hydrogen supply during the pyrolysis of bagasse. The body provides a catalytically active site for hydrogenation of 4-vinylphenol and its precursors to promote the formation of 4-ethylphenol. Incidentally, the activated carbon obtained by other methods of activation (e.g. ZnCl _2, H ₃ PO ₄ and activated carbon and other chemical KOH activation obtained using activated carbon obtained by activating a physical method such as CO ₂₎ do not have the catalytic effect, only Only the activated carbon obtained by the steam activation method has the catalytic effect.

However, the yield and selectivity of 4-ethylphenol are limited by relying solely on activated carbon to catalyze the pyrolysis of bagasse. The greatest beneficial effect of the present invention is also that hydrogen is used as the reaction gas, and the synergistic action with the activated carbon catalyst provides a large yield and selectivity of 4-ethylphenol. Hydrogen as a hydrogen source in activated carbon Catalyzed as an effective hydrogen donor and reacted with 4-vinylphenol and its precursor to selectively form 4-ethylphenol. The use of activated carbon catalyst alone, due to the lack of sufficient effective hydrogen donor in the pyrolysis system, limits the formation of 4-ethylphenol; hydrogen alone, in the pyrolysis system can not react with 4-vinyl phenol and its precursors It can not promote the formation of 4-ethylphenol; when hydrogen and activated carbon are used together, there are basically no complex unsaturated (including C=C bond) pyrolysis products generated during biomass pyrolysis. The effect of catalytic hydrogenation exhibits excellent catalytic hydrogenation effect only for 4-vinylphenol and its precursors, thereby enabling selective preparation of 4-ethylphenol. Based on this feature, the yield and selectivity of 4-ethylphenol prepared by activated carbon catalyzed pyrolysis of bagasse under hydrogen atmosphere is much higher than that of previously reported activated carbon catalytic pyrolysis of bagasse under nitrogen atmosphere. The yield and selectivity of ethyl phenol, the highest yield is increased by at least 1.5 times, and the selectivity is also greatly increased. Due to the high purity of 4-ethylphenol in the liquid product, subsequent separation and purification is relatively simple. In addition, the mixture of coke formed by pyrolysis of bagasse and activated carbon catalyst can be activated by steam to obtain activated carbon, and is further used for preparing 4-ethylphenol.

detailed description

The invention provides a method for preparing 4-ethylphenol by catalytic pyrolysis of bagasse with activated carbon, and the invention is further described below in conjunction with specific embodiments.

The percentages in the following examples are all by mass unless otherwise stated.

Example 1

100g of dried rice husk (particle size of 0.1-0.3mm) was used as raw material, and then it was raised from room temperature to 400 ° C at a heating rate of 15 ° C / min under an inert atmosphere and carbonized at a constant temperature for 1 h. After cooling, it was cooled under a steam atmosphere. The heating rate of 25 ° C / min was raised from room temperature to 800 ° C and activated at a constant temperature for 2 h, and after cooling, 29 g of activated carbon was obtained.

Take 10g of the above activated carbon as a catalyst, take 10g of sugar cane bagasse (particle size of 0.1-0.3mm) as raw material, mechanically mix the two at 270 ° C, the heating rate is greater than 800 ° C / s, hydrogen and nitrogen concentration are respectively 11 vol% And pyrolysis for 30 s in an atmosphere of 89 vol%, the yield of the liquid product was 32.7%, and the content of 4-ethylphenol was analyzed by gas chromatography, and the yield of 4-ethylphenol was calculated to be 3.5%; The content of ethylphenol in the organic liquid product (excluding water) was 22.3%.

Example 2

Using 15g of activated carbon prepared in the first embodiment as a catalyst, 10g of sugar cane bagasse (particle size of 0.1-0.3mm) was used as raw material, and the two were mechanically mixed at 300 ° C, the heating rate was higher than 1000 ° C / s, and the hydrogen and nitrogen concentrations were respectively The product was pyrolyzed for 25 s in an atmosphere of 10 vol% and 90 vol%, and the yield of the liquid product was 36.8%. The content of 4-ethylphenol was analyzed by gas chromatography, and the yield of 4-ethylphenol was calculated to be 3.9%. The content of 4-ethylphenol in the organic liquid product (excluding water) was 20.2%.

Example 3

80g of dried poplar (particle size of 0.1-0.3mm) was used as raw material, and then it was raised from room temperature to 500 ° C at a heating rate of 10 ° C / min under an inert atmosphere and carbonized at a constant temperature for 1.5 h, and cooled under a steam atmosphere. The temperature was raised from room temperature to 900 ° C at a heating rate of 30 ° C / min and the temperature was activated for 2.5 h. After cooling, 22 g of activated carbon was obtained.

Take 8g of the above activated carbon as a catalyst, take 16g of fruit bagasse (particle size of 0.1-0.3mm) as raw material, mechanically mix the two at 330 ° C, the heating rate is greater than 700 ° C / s, the hydrogen and nitrogen concentrations are respectively 12 vol% and Pyrolysis for 20 s in an atmosphere of 88 vol%, the yield of the liquid product was 39.2%, and the content of 4-ethylphenol was analyzed by gas chromatography, and the yield of 4-ethylphenol was calculated to be 3.1%; The content of phenol in the organic liquid product (excluding water) was 14.5%.

Example 4

Take 10g of activated carbon prepared in the implementation of 3 as a catalyst, take 5g of fruit bagasse (particle size of 0.1-0.3mm) as raw material, mechanically mix the two at 310 ° C, the heating rate is greater than 800 ° C / s, hydrogen and nitrogen concentration respectively Pyrolysis for 9 s in an atmosphere of 9 vol% and 91 vol%, obtaining a liquid product yield of 37.3%, passing gas The content of 4-ethylphenol was analyzed by phase chromatography, and the yield of 4-ethylphenol was calculated to be 3.2%; the content of 4-ethylphenol in the organic liquid product (excluding water) was 16.3%.

Example 5

120g of dried corn stalk (particle size of 0.1-0.3mm) was used as raw material, and then heated from room temperature to 450 ° C at a heating rate of 12 ° C / min under an inert atmosphere and carbonized at a constant temperature for 1.5 h, and cooled under a steam atmosphere. It was raised from room temperature to 850 ° C at a heating rate of 25 ° C / min and activated at a constant temperature for 3 h, and after cooling, 35 g of activated carbon was obtained.

Taking 20 g of the above activated carbon as a catalyst, taking 10 g of sugar cane bagasse (particle size of 0.1-0.3 mm) as a raw material, mechanically mixing the two at 290 ° C, the heating rate is greater than 100 ° C / s, the hydrogen and nitrogen concentrations are respectively 9 vol % and Pyrolysis for 25 s in an atmosphere of 91 vol%, the yield of the liquid product was 35.5%, and the content of 4-ethylphenol was analyzed by gas chromatography, and the yield of 4-ethylphenol was calculated to be 3.2%; The content of phenol in the organic liquid product (excluding water) was 17.4%.

Example 6

Take 12g of activated carbon prepared in the implementation of 5 as a catalyst, take 8g of fruit bagasse (particle size of 0.1-0.3mm) as raw material, mechanically mix the two at 300 ° C, the heating rate is greater than 600 ° C / s, hydrogen and nitrogen concentration respectively Pyrolysis for 15 s in an atmosphere of 11 vol% and 89 vol%, the yield of the liquid product was 36.3%, and the content of 4-ethylphenol was analyzed by gas chromatography, and the yield of 4-ethylphenol was calculated to be 3.0%. The content of 4-ethylphenol in the organic liquid product (excluding water) was 15.9%.

Example 7

90g of dried bamboo leaves (particle size of 0.1-0.3mm) was used as raw material, and then heated from room temperature to 500 ° C at a heating rate of 13 ° C / min under an inert atmosphere and carbonized at a constant temperature for 2 h, and then cooled under a water vapor atmosphere. The temperature rising rate of 28 ° C / min was raised from room temperature to 880 ° C and activated at a constant temperature for 2.5 h, and after cooling, 26 g of activated carbon was obtained.

Take 12g of the above activated carbon as a catalyst, and take 12g of sugar cane bagasse (particle size of 0.1-0.3mm) as raw material. The two were mechanically mixed and pyrolyzed for 25 s at 300 ° C, a heating rate higher than 780 ° C / s, and a hydrogen and nitrogen concentration of 10 vol % and 90 vol %, respectively, to obtain a liquid product yield of 35.9%, which was analyzed by gas chromatography. The content of 4-ethylphenol was calculated to be 3.5% in terms of 4-ethylphenol; the content of 4-ethylphenol in the organic liquid product (excluding water) was 18.7%.

Example 8

Take 6g of activated carbon prepared in the implementation of 7 as a catalyst, take 12g of fruit bagasse (particle size of 0.1-0.3mm) as raw material, mechanically mix the two at 320 ° C, the heating rate is greater than 700 ° C / s, hydrogen and nitrogen concentration respectively The product was pyrolyzed for 20 s in an atmosphere of 10 vol% and 90 vol% to obtain a liquid product yield of 38.1%. The content of 4-ethylphenol was analyzed by gas chromatography, and the yield of 4-ethylphenol was calculated to be 3.2%. The content of 4-ethylphenol in the organic liquid product (excluding water) was 15.6%.

Example 9

8g of activated carbon prepared in the implementation of 7 as a catalyst, 6g of sugar cane bagasse and bagasse mixture (3g of sugar cane bagasse, 3g of bagasse) as raw materials, the catalyst and raw materials are mixed at 300 ° C, the heating rate is greater than 900 ° C / s, The hydrogen and nitrogen concentrations were pyrolyzed for 25 s in an atmosphere of 11 vol% and 89 vol%, respectively, and the yield of the liquid product was 36.8%. The content of 4-ethylphenol was analyzed by gas chromatography, and the content of 4-ethylphenol was calculated. The yield was 3.4%; the content of 4-ethylphenol in the organic liquid product (excluding water) was 17.4%.

The above is only the preferred embodiment of the present invention, and is not intended to limit the present invention. Any modifications, equivalents, improvements, etc., which are made within the spirit and principles of the present invention, should be included in the present invention. Within the scope of.

Claims

A method for preparing 4-ethylphenol by catalytically pyrolysis of bagasse with activated carbon, characterized in that bagasse is used as raw material and activated carbon is used as catalyst, and mass ratio of bagasse and activated carbon catalyst is (10:1) to (1: 5) Mechanical mixing, then rapid pyrolysis under hydrogen atmosphere at 240-410 ° C, pyrolysis reaction time less than 50 s, condensation of pyrolysis gas to obtain a liquid rich in 4-ethylphenol product.
The method for preparing 4-ethylphenol by the activated carbon catalytic pyrolysis of bagasse according to claim 1, wherein the activated carbon catalyst is activated carbon prepared by a biomass activation method by a steam activation method.
The method for preparing 4-ethylphenol by catalytically pyrolyzing bagasse of activated carbon according to claim 1, wherein the bagasse is a bagasse or a sugar cane bagasse or a mixture of the two.
The method for preparing 4-ethylphenol by catalytically pyrolyzing bagasse of activated carbon according to claim 1, wherein the hydrogen atmosphere refers to a mixture of hydrogen and an inert oxygen-free protective gas in the reaction system. .
The method for preparing 4-ethylphenol by the activated carbon catalytic pyrolysis of bagasse according to claim 4, wherein the concentration of hydrogen in the mixed gas is 2 to 14 vol%.
The method for preparing 4-ethylphenol by the activated carbon catalytic pyrolysis of bagasse according to claim 1, wherein the pyrolysis reaction has a heating rate higher than 100 ° C / s.