CN114181726A

CN114181726A - Method for synthesizing aviation kerosene cycloparaffin and arene by using waste polycarbonate plastic

Info

Publication number: CN114181726A
Application number: CN202010970550.1A
Authority: CN
Inventors: 李宁; 王璐琳; 张涛; 李广亿; 王爱琴; 王晓东; 丛昱
Original assignee: Dalian Institute of Chemical Physics of CAS
Current assignee: Dalian Institute of Chemical Physics of CAS
Priority date: 2020-09-15
Filing date: 2020-09-15
Publication date: 2022-03-15
Anticipated expiration: 2040-09-15
Also published as: CN114181726B

Abstract

The present invention provides a novel process for converting waste polycarbonate plastic into aviation kerosene range cycloalkanes and aromatics. Firstly, taking an alcohol compound as a solvent and a hydrogen source, and taking Raney metal as a bifunctional catalyst to catalyze alcohol hydrogen supply and polycarbonate hydrodeoxygenation to obtain a primary product which is an incomplete hydrodeoxygenation product; and then adding an acidic molecular sieve into the reaction liquid, and further deoxidizing the primary hydrodeoxygenation product to obtain a series of naphthenic hydrocarbon and aromatic hydrocarbon in the range of aviation kerosene. The invention reasonably solves the problems that the previous degradable plastics have harsh conditions and the environment is polluted by the degradation products, and the whole synthesis process is environment-friendly, low in cost and safe to operate.

Description

Method for synthesizing aviation kerosene cycloparaffin and arene by using waste polycarbonate plastic

Technical Field

The invention belongs to the technical field of chemical synthesis, and particularly relates to a method for synthesizing aviation kerosene range hydrocarbon compounds.

Background

Petroleum, coal and natural gas are important energy substances in the modern society, and have always occupied a very important position in daily life and production of people, and have also deeply influenced the development of all countries in the world. The double-edged sword brings great progress and convenience to the whole society, and brings a series of serious environmental problems such as greenhouse effect, acid rain, haze and the like. Therefore, the development of new energy sources capable of replacing fossil resources has important strategic significance. The aviation kerosene is a space flight aviation fuel with large international demand, and has the advantages of high flash point, low freezing point, high density, high combustion heat value and the like when being used as a fuel of an aircraft. Nowadays, aviation kerosene is mainly extracted from petroleum. In recent years, the replacement of petroleum for preparing aviation kerosene has become a research hotspot due to the over-exploitation of fossil resources and the growing concern of people on environmental problems.

The use of plastics has penetrated aspects of human life such as packaging, agriculture, shipping, construction, telecommunications, education, medicine, transportation, defense, consumer goods and the like. One of the reasons for the wide range of applications of plastics is due to their ease of processing and ease of use. Most plastics are high molecular weight organic polymers, the structure of which is composed of many monomers forming repeating units. The plastic may be classified into polyethylene terephthalate (PET), polyvinyl chloride (PVC), polypropylene (PP), Polycarbonate (PC), and the like according to its composition. To date, over 83 billion metric tons of plastic have been produced globally, and most of the used plastic is not recycled and discarded in landfills or in the natural environment. In 2015, the plastic production was 6300 tons, of which 9% would be recycled, 12% would be incinerated, and 79% would be deposited in landfills or directly discarded in the natural environment. Most of the plastic monomers are not easily biodegraded, and if the plastic monomers are directly discarded without treatment, serious environmental problems can be caused, and the survival and development of terrestrial and marine organisms are damaged. The plastic production uses 4% -8% of the global petroleum yield, so the repeated use of the plastic can save global fossil fuels and simultaneously reduce the emission of carbon dioxide, nitrogen oxides and sulfur dioxide.

The methods for treating solid plastic waste are roughly divided into four types, namely, primary recovery (re-extrusion molding), secondary recovery (mechanical treatment), tertiary recovery (chemical treatment) and quaternary recovery (energy recovery). Primary recycling, which is generally the re-introduction of industrial or mono-polymer plastic edges and parts into the extrusion cycle for extrusion to produce products of similar material composition, is generally only applicable to the line itself and is rarely recycled, since the quality of the recycled material is already unsatisfactory. The process of mechanical recovery is typically a physical process, generally consisting of several steps of cutting, contaminant separation, floating, grinding, washing and drying, agglomeration, extrusion, quenching. Various waste materials are mechanically recycled raw materials that are processed into smaller sized materials, formed into different shapes and sizes, such as pellets, flakes or powders, depending on the source, shape and range of applications of the raw materials. And (4) mechanically recovering. Chemical recycling in recent years has promoted recycling of solid plastic waste, including gasification, pyrolysis, hydrogenation and other treatment methods, which decompose plastics into small molecules and then use these small molecules to produce chemical products or re-use them as raw materials for plastics. When the degradation environment is ethylene glycol, the degradation of the polymer is known as glycolysis; in the presence of methanol, the degradation of the polymer is known as methanolysis, where alcoholysis is also a transesterification reaction. Energy recovery is a general strategy to address solid waste plastics, involving total or partial oxidation of the recovered material, producing heat, power and fuel.

Polycarbonates are a class of thermoplastic high molecular polymers having carbonate as a basic repeating unit, and broadly, polycarbonates include any polymer having carbonate groups, and are classified into aliphatic, alicyclic, and aromatic groups, but bisphenol a (bpa) polycarbonates are most widely used, and thus are also generally referred to as bisphenol a polycarbonates.

Jiao Guo(Industrial&Engineering Chemistry Research,2018,57(32):10915-]Cl 2.0FeCl3, used for alcoholysis of PC, and recovering BPA monomer. Demonstrated by kinetic studies using [ Bmim]Cl·2.0FeCl₃The methanol decomposition of PC by the catalyst is a first-order reaction, and the activation energy is 98.9 kJ.mol^-1Lower than the reported [ Bmim ]][Ac]A catalyst. According to the reaction mechanism, [ Bmim ]]Cl·2.0FeCl₃Due to the synergy between the lewis acidity of the anion and the electrostatic interaction of the cation. At the same time the article proposes possible reaction paths: firstly, Fe at the Lewis acid part of the catalyst is connected with an oxygen atom on a PC carbonyl group to form an Fe-O adduct, and electrons are deviated from the oxygen atom to iron so that the oxygen shows electropositivity; at the same time, the cationic site of the catalyst [ Bmim ]]⁺The carbonyl group is further activated by electrostatic interaction, making the oxygen more electropositive. The electropositive oxygen atom is an unstable intermediate, and by electron transfer, the electropositive transfer of oxygen to the carbonyl carbon to which it is attached, makes the carbon a site of a positive point, which facilitates the reaction of the alcohol with the carbonyl group, whereupon the alcohol then undergoes nucleophilic attack on the carbonyl carbon, causing the PC to form oligomers and to break off small molecules. As the reaction proceeds, PC gradually decomposes to eventually yield BPA and carbonate. However, BPA produced by depolymerization of polycarbonate is an endocrine disrupter in the environment, and if it is released into the environment during the recycling process, it causes environmental pollution.

Jia Wang (Journal of Hazardous Materials,2020,386) et al used HNA-ZSM-5 model molecular sieves as catalysts for fast co-pyrolysis of Polycarbonate (PC) and hydrogen-rich plastics (polystyrene (PS), polypropylene (PP), Polyethylene (PE)) to form monocyclic aromatics, with PS being the most efficient hydrogen donor. The catalyst type plays an important role in the catalytic decomposition of PC waste, and H-ZSM-5 has a better catalytic effect compared with HY molecular sieve. While the influence of the Si/Al ratio of H-ZSM-5 on the distribution of the Monocyclic Aromatic (MAHs) products, a Si/Al ratio of 38 allows the benzene yield to be maximized. In testing the temperature, which is a factor, there is a competitive reaction between the aromatic hydrocarbon compound and the aromatic oxygen-containing compound, and the selectivity of the aromatic hydrocarbon is maximized when the catalytic degradation temperature is 700 ℃. However, such high reaction temperature makes the reaction conditions extremely severe, and the requirements for the reactor are also much higher.

In the article (Green Chemistry,2019,21(14):3789-3795), the high-density aviation fuel is synthesized by using the polycarbonate plastic as a starting point through methanolysis and hydrodeoxygenation. The experiment is totally divided into two steps, wherein in the first step, PC is subjected to alcoholysis for 3 hours at the temperature of 453K without adding any catalyst, and the alcoholysis product is BPA. In the tests of various alcohol reagents, the alcoholysis effect of methanol is the best, and the yield can reach 89%. And in the second step, BPA is subjected to Hydrodeoxygenation (HDO) to obtain cycloalkane, when a metal catalyst is used alone, hydroxyl exists in the product, and in order to further remove hydroxyl oxygen, an acidic molecular sieve is introduced for dehydration to generate olefin, and the olefin can be continuously hydrogenated to generate alkane under the condition of hydrogen. In the catalyst subjected to repeated screening and hydrodeoxygenation, the catalytic reagent combination with the best catalytic effect is Pt/C and H-beta, BPA is subjected to hydrodeoxygenation under the co-catalytic action of the Pt/C and the H-beta, and the total yield of C13-C15 is about 80%. However, the supported noble metal catalyst used in the experiment is high in price and cost, and is not beneficial to industrial popularization.

Disclosure of Invention

The invention aims to provide a new route for preparing aviation kerosene by using waste carbonate plastics as raw materials. Wherein, the used catalyst is commercial catalyst Raney metal and acidic molecular sieve which are cheap and easy to obtain, so that the preparation cost is greatly reduced; meanwhile, alcohols are used as hydrogen sources, so that the danger of directly using hydrogen is avoided. The invention is realized by the following technical scheme:

the method is characterized in that waste polycarbonate plastic is used as a raw material, and an aviation kerosene range hydrocarbon compound is prepared by a one-pot two-step method:

firstly, taking alcohols as a reaction solvent and as a hydrogen source of the whole reaction, and carrying out alcoholysis and hydrodeoxygenation on polycarbonate under the action of a Raney metal catalyst to generate the following incomplete hydrodeoxygenation products 2-7; the mass ratio of the Raney metal to the polycarbonate is 0.005-2;

secondly, carrying out further hydrodeoxygenation reaction on the reaction product of the first step under the catalytic action of an acidic molecular sieve to generate high-density fuel aromatic hydrocarbons and naphthenic hydrocarbons 8-12 in the following aviation kerosene range; the mass ratio of the acidic molecular sieve to the polycarbonate is 0.005-1

Further, the alcohol and Raney metal catalyst used in the first step is one of the following alcohols and Raney metals:

alcohols: methanol, ethanol, isopropanol, cyclopentanol, cyclohexanol;

raney metal: raney nickel, Raney iron, Raney cobalt, Raney copper, Raney nickel iron.

Wherein the weighed mass of the Raney metal is wet weight, and the water content is about 10-60%.

The acidic molecular sieve used in the second step is one of Na-ZSM-5, H-USY, Al2O3, SiO2 or H-beta.

Further, the alcoholysis and preliminary hydrodeoxygenation reactions of the polycarbonate in the first step are carried out in a kettle-type reactor; the concentration of the substrate polycarbonate is 0.001-1 g/ml; the reaction temperature is 100-260 ℃; the reaction time is 0.5-24 h. In the second step, after adding an alcohol solvent with the volume ratio of 0.01-5 into the reaction liquid in the first step, carrying out further hydrodeoxygenation reaction in a kettle type reactor; the reaction temperature is 100-250 ℃; the reaction time is 0.5-24 h.

Further, in the first step, it is preferable that the mass ratio of the Raney metal to the reaction substrate polycarbonate is 0.01 to 0.8. In the second step, the mass ratio of the acidic molecular sieve to the reaction substrate polycarbonate is preferably 0.1 to 0.7.

Further, in the first step, it is preferable that the preferable concentration range of the substrate polycarbonate is 0.005 to 0.5 g/ml. In the second step, the reaction is continued on the basis of the reaction solution in the first step to supplement the solvent, and the supplement volume ratio is preferably 0.1-2.

Further, in the first step, the reaction temperature is preferably between 160 ℃ and 220 ℃. In the second step, the reaction temperature is preferably between 150 ℃ and 210 ℃.

The optimal synthesis method of the technical scheme comprises the following steps:

firstly, selecting a Raney nickel catalyst, wherein the reaction temperature is 120-260 ℃, and preferably 180-220 ℃; the reaction time is 0.5h-24h, preferably 1h-6 h; the ratio of the mass of the Raney nickel catalyst to the reaction substrate is between 0.01 and 1, and the ratio of the mass of the Raney nickel catalyst to the reaction substrate is preferably between 0.01 and 0.8.

Secondly, selecting a catalyst H-USY, wherein the reaction temperature is between 100 and 250 ℃, and preferably between 150 and 240 ℃; the reaction time is between 0.5 and 24 hours, and the preferable reaction time is between 1 and 6 hours; the ratio of the mass of the catalyst H-USY to the reaction substrate is between 0.01 and 1, and the ratio of the mass of the catalyst H-USY to the reaction substrate is preferably between 0.01 and 0.6.

The present application does not address the degradation of PC to bisphenol a as in previous studies, but rather focuses on the further conversion of PC, i.e. the hydrodeoxygenation, to high value fuels. In the first step of reaction, raney metal is used as a bifunctional catalyst to promote deprotonation and hydrogen supply of alcohol compounds and promote a substrate to carry out hydrodeoxygenation reaction, and alcoholysis reaction and hydrodeoxygenation reaction are carried out in one step, so that an alcoholysis product is generated, and the substrate is subjected to preliminary hydrodeoxygenation, and alcoholysis and preliminary hydrodeoxygenation products can be obtained. In the second step of reaction, the prior noble metal is not loaded on the molecular sieve, but the commercial molecular sieve is directly used for hydrodeoxygenation, so that the process flow is greatly simplified, and the use cost of the reaction is reduced; and meanwhile, an external hydrogen source is avoided, and the safety of the experiment is improved. The generated additional products, 4-methyl-2-pentanol and 4-methyl-2-pentanone, can be used as a solvent in the manufacture of lubricating oil additives and a solvent of synthetic rubber respectively.

Compared with the prior art, the invention has the following advantages:

1. the synthetic route of aromatic hydrocarbon and naphthenic hydrocarbon compounds in the aviation kerosene range provided by the invention takes the waste plastic polycarbonate as the starting material, the raw material source is wide, cheap and easily available, the waste is effectively changed into valuable, and the waste plastic is reasonably utilized.

2. The alcoholysis reaction and the hydrodeoxygenation reaction adopt commercial Raney metal catalysts and acidic molecular sieves as hydrogenation catalysts, and are cheap and easy to obtain, and the cost is low.

3. The aromatic hydrocarbon and the naphthenic hydrocarbon in the aviation kerosene range, which are prepared by the synthetic method, have higher density.

Drawings

FIG. 1-GC spectra of alcoholysis and preliminary hydrodeoxygenation of polycarbonate;

FIG. 2-GC spectrum of the second step hydrodeoxygenation product.

The specific implementation mode is as follows:

the invention will now be illustrated by means of specific examples, without restricting its scope to these examples.

Examples 1 to 39

Alcoholysis and preliminary hydrodeoxygenation reactions are carried out in a high-pressure reaction kettle, a certain amount of waste polycarbonate (4g) and 25ml of isopropanol solvent are added into the reaction kettle, a certain amount of Raney metal catalyst is added, and the mixture is mechanically stirred and reacted for a specific time at a certain temperature.

TABLE 1 alcoholysis and hydrodeoxygenation Activity of different catalysts

The results in table 1 show that raney cobalt, raney nickel, raney iron, raney copper, raney nickel iron catalysts have better activity for alcoholysis reaction and hydrodeoxygenation. The reaction conditions have a certain influence on the catalyst activity. Raney cobalt and Raney nickel are used as catalysts to optimize reaction conditions (temperature, time and catalyst dosage). Along with the optimization of reaction conditions, Raney cobalt and Raney nickel are used as catalysts, and the yield is over 80 percent.

Examples 40 to 56

Alcoholysis and preliminary hydrodeoxygenation reactions are carried out in a high-pressure reaction kettle, a certain amount of waste PC and 25ml of alcohol solvent are added into the reaction kettle each time, a certain amount of Raney nickel catalyst is added, and the reaction is carried out at the reaction temperature of 210 ℃ for 4 h.

TABLE 2 Effect of different solvents on the reactivity

As can be seen from the results in Table 2, methanol, ethanol, isopropanol, cyclopentanol and cyclohexanol all have a good effect on the reaction among the solvents used. The influence of the substrate quality on the reaction was examined with methanol, ethanol, isopropanol. As a result, it was found that the yield increased with decreasing mass of the substrate, and that the yield did not change when the mass was decreased to a certain value.

Examples 57 to 95

The primary reaction product is still placed in a high-pressure reaction kettle, a certain amount of acidic molecular sieve is directly added after the kettle is opened, and the reaction is carried out for a period of time at a certain temperature.

TABLE 3 hydrodeoxygenation reactivity of different catalysts

As can be seen from the data in Table 3, the acidic molecular sieves contained H-beta, H-USY, H-ZSM-5, Na-ZSM-5, and Al₂O₃And SiO₂All have better catalytic effect. The reaction conditions have a certain influence on the catalyst activity. The reaction conditions (temperature, time and catalyst dosage) are optimized by taking H-beta and H-USY as catalysts. With the optimization of reaction conditions, the yield of over 70 percent can be obtained by using H-USY as a catalyst.

Examples 96 to 99

0.3g of H-USY molecular sieve is added into a high-pressure reaction kettle filled with the primary product, a certain volume of isopropanol is supplemented on the basis of the original solvent, and the reaction is carried out for 6 hours at 190 ℃.

TABLE 4 Effect of additional solvent volume on Hydrodeoxygenation reactivity

As can be seen from the data in Table 4, solvent addition has some effect on the yield of the hydrodeoxygenated product, and solvent addition can suitably increase the product yield. When the additional solvent mass reaches a certain volume, the hydrodeoxygenation product yield is almost unchanged.

Example 100-

The density of the product components was measured at room temperature using a densitometer and the densities of the components are shown in the table.

TABLE 5 Density of the component products

From the above examples, it can be seen that the preparation of higher density aviation kerosene range aromatics and hydrocarbons 8-12 from polycarbonate plastics is fully achieved by a one-pot two-step process using the inexpensive and readily available commercial catalysts raney metal and acidic molecular sieves. This process need not add extra hydrogen, and the experiment is comparatively safe in operation, and whole process is comparatively green.

Claims

1. The preparation method of the hydrocarbon compound is characterized in that the waste polycarbonate plastic is used as a raw material, and the aviation kerosene range hydrocarbon compound is prepared by a one-pot two-step method, and comprises the following steps:

firstly, carrying out alcoholysis and preliminary hydrodeoxygenation reaction on polycarbonate in an alcohol solvent under the catalysis of Raney metal to obtain a first-step reaction liquid; the first-step reaction liquid contains 2-7 of a primary hydrodeoxygenation product; the weight ratio of the Raney metal to the polycarbonate is 0.005-2;

wherein n is 20-200;

secondly, adding an acidic molecular sieve into the reaction liquid in the first step for further hydrodeoxygenation reaction to prepare an aviation kerosene range hydrocarbon compound 8-12; the weight ratio of the acidic molecular sieve to the polycarbonate is 0.005-1

2. The method of claim 1, wherein: the Raney metal is one of Raney nickel, Raney iron, Raney cobalt, Raney copper or Raney nickel iron; the weighed mass of the Raney metal is wet weight, and the water content is 10-60%; the alcohol solvent is one of methanol, ethanol, isopropanol, cyclopentanol or cyclohexanol.

3. The method of claim 1, wherein: the acidic molecular sieve is one of Na-ZSM-5, H-USY, Al2O3, SiO2 or H-beta.

4. The method of claim 1, wherein: in the first step, alcoholysis and preliminary hydrodeoxygenation of polycarbonate are carried out in a kettle-type reactor; the concentration of the polycarbonate is 0.001-1 g/ml; the reaction temperature is 100-260 ℃; the reaction time is 0.5-24 h;

in the second step, after adding an alcohol solvent with the volume ratio of 0.01-5 into the reaction liquid in the first step, carrying out further hydrodeoxygenation reaction in a kettle type reactor; the reaction temperature is 100-250 ℃; the reaction time is 0.5-24 h.

5. The method of claim 4, wherein: in the first step, the concentration of the polycarbonate is 0.005-0.5 g/ml; in the second step, the alcohol solvent with the volume ratio of 0.1-2 is added into the reaction liquid in the first step.

6. The method of claim 4, wherein: in the first step, the reaction temperature is 160-220 ℃; in the second step, the reaction temperature is 150-210 ℃.

7. The method of claim 1, wherein: in the first step, the mass ratio of the Raney metal to the polycarbonate is 0.01-0.8; in the second step, the mass ratio of the acidic molecular sieve to the polycarbonate is 0.1-0.7.

8. The method of claim 4, wherein: in the first step, the Raney metal is Raney nickel, the reaction temperature is 120-260 ℃, the reaction time is 0.5-24h, and the mass ratio of the Raney nickel to the polycarbonate is 0.01-1; in the second step, the acidic molecular sieve is H-USY, the reaction temperature is 100-250 ℃, the reaction time is 0.5-24H, and the mass ratio of the H-USY to the polycarbonate is 0.01-1.

9. The method of claim 8, wherein: in the first step, the reaction temperature is 180-220 ℃, the reaction time is 1-6h, and the mass ratio of the raney nickel to the polycarbonate is 0.01-0.8; in the second step, the reaction temperature is 150-240 ℃, the reaction time is 1-6H, and the mass ratio of H-USY to polycarbonate is 0.01-0.6.