CN109913255B

CN109913255B - Method for preparing liquid fuel by using TDI tar residues

Info

Publication number: CN109913255B
Application number: CN201910304883.8A
Authority: CN
Inventors: 李静玲; 陈荣国; 余根鼎; 陈友根; 龚凌诸; 杜逸兴; 林琅; 陈君; 王诣婧
Original assignee: Fujian University of Technology
Current assignee: Fujian University of Technology
Priority date: 2019-04-16
Filing date: 2019-04-16
Publication date: 2021-07-30
Anticipated expiration: 2039-04-16
Also published as: CN109913255A

Abstract

The invention relates to a method for preparing liquid fuel by Toluene Diisocyanate (TDI) tar residues. Grinding tar residue particles generated in the production process of TDI, placing the ground tar residue particles in a high-temperature high-pressure reaction kettle, adding a low-boiling-point polar solvent according to a certain proportion, and uniformly stirring. Controlling the temperature, pressure and time to carry out digestion reaction, thus obtaining a digestion solid-liquid mixture. Filtering, and performing solid-liquid separation to obtain digestion filtrate and digestion solid residue respectively. And (5) digesting the solid residue for later use. And adding the mixed fuel accelerator into the digestion filtrate according to a certain mass percentage to obtain the liquid fuel. The tar residue disposal method has the advantages of low cost, simple process, convenient operation, easily controlled conditions and less equipment investment. The liquid fuel has high heat value and small risk of secondary pollution caused by the emission of combustion products. The ecological environment is protected while great economic benefit is generated, and the aims of energy conservation, emission reduction and environmental protection of recycling, reduction and harmless recycling of the solid waste of the tar residues are fulfilled.

Description

Method for preparing liquid fuel by using TDI tar residues

Technical Field

The invention belongs to the technical field of chemical recovery, and relates to a method for preparing liquid fuel by using TDI tar residues.

Background

Liquid fuels are a large class of fuels. Liquid combustible material capable of generating thermal or kinetic energy. Mainly containing hydrocarbons or mixtures thereof. The processed oil includes gasoline, kerosene, diesel oil, fuel oil, etc. obtained by processing petroleum, shale oil obtained by dry distillation of oil shale, artificial stone oil, etc. synthesized from carbon monoxide and hydrogen. In the face of the depletion of petrochemical energy, alternative liquid fuels including biomass fuels are the most potential new alternative energy sources.

The biological liquid fuel prepared from crop straws, agricultural processing residues, industrial wastewater, waste residues, municipal domestic garbage and the like is green and environment-friendly energy, is completely combusted, has high heat conversion efficiency, mainly discharges water and carbon dioxide, has little environmental pollution, and is the most clean, environment-friendly and most potential fuel for development in the future.

The biological liquid fuel has obvious economic benefit, and the high heat efficiency is the best characteristic. Due to the difficulty of the preparation or synthesis technology, the method needs deep technical research and practice.

Toluene Diisocyanate (TDI) has two isomers of 2, 4-Toluene diisocyanate and 2, 6-Toluene diisocyanate, and the commercial product is a mixture of the two isomers.

In recent years, with the great increase of the demand of TDI due to the development of the polyurethane industry, the increase speed of TDI in recent years is 7 percent in China. According to the unit forecast, the global TDI consumption demand will increase at a rate of 4% per year within the next 10 years. The TDI market both internationally and domestically has great development space.

The worldwide TDI production method still takes the phosgenation method as a main method. During the processes of gas making, water gas purification, carbon monoxide refining, phosgene synthesis, catalyst preparation, TDA production, TDI production and the like in the phosgenation production process, and during the storage of intermediate products and finished products and the like, a large amount of pollutants such as waste gas, waste water, waste residues and the like can be generated. Wherein the TDI tar residue is a solid waste particle generated in the production process of TDI.

The main sources of solid waste generation generated during TDI production: (1) in the gas making section, the residue mainly comprises active carbon, molecular sieve, silica gel and a small amount of catalyst such as platinum, palladium, iron and manganese. (2) The chlorination section produces carbon black. (3) The TDI section produces o-toluenediamine (OTD). (4) Phosgene synthesis produces activated carbon. (5) TDI recovery produces particles of tar residue.

Research shows that after high-temperature treatment, the main component of tar residue particles generated by TDI recovery is mainly isocyanate, and polymers such as urea, biuret and polymerized biuret are accompanied. These polymers contain the main structural components necessary for the preparation of biological liquid fuels.

How to adopt an effective technical method and convert the heat value of the biomass into a substance with high heat value, less pollution and environmental friendliness has important significance.

The existing mature TDI tar residue treatment method mainly relates to the following three methods: distillation-evaporation, distillation-reduction, distillation-combustion, and the like. The method aims to recycle intermediate products or derivatives required by TDI production.

The above-described main three disposal methods for tar residues are described below.

Whether by distillation-evaporation or distillation-reduction. And (3) rectifying the tar residue by a strong alkali solution, a high-boiling-point organic solvent and a reducing agent in a high-temperature, high-pressure/vacuum sectional manner, and respectively recovering low-boiling-point micromolecule substances and high-boiling-point substances.

The method has the advantages that: high recovery rate (over 90%) and less environmental pollution. The main disadvantages are that the equipment investment is large, the process control is complex and strict, the operation difficulty is large, and toxic and harmful substances are easy to generate secondarily, such as waste liquid and waste residue containing a large amount of strong alkali substances, and secondary environmental pollution is easy to generate.

Birongshan and the like respectively disclose in two patent claims of 'a continuous removal method for TDI residues by a heavy oil method' (No. CN 105384633B) and 'a continuous removal device for the TDI residues by the heavy oil method' (CN 105523925B), wherein the DEIP is recovered by using a distillation method and an evaporation method by using tar residues generated in the production of the TDI by the high-boiling-point heavy oil method as raw materials and using diethyl isophthalate (DEIP) as a heavy oil agent.

The patent claim of "a method for recovering DEIP from TDI residues" (CN 101717335B) of Li Guixian et al is characterized in that after high boiling point residues generated in TDI production are subjected to free TDI removal, residual solid residues are extracted by taking ethanol as an extracting agent (comprising methanol, ethanol, benzene and toluene) at the critical temperature and the critical pressure of the extracting agent, the extraction time is 15-25 min, the solid-liquid ratio is 1: 4-1: 16, and the particle size of residue particles is 100 meshes of undersize products. Extracting DEIP in TDI residues by an extracting agent in a stirring reaction kettle and recycling.

The specific reaction conditions are as follows: a) the TDI solid residue was ground into particles and then sieved for effective extraction and particle size reduction and then sieved through a 100 mesh screen. b) Adding the undersize product and an extracting agent into a reaction kettle with a stirrer, and extracting at the reaction pressure of 2-6 MPa and the temperature of 150-250 ℃. c) DEIP is recovered from the liquid after extraction. The extractant in the extraction engineering can be repeatedly recycled.

Distillation-reduction process. The tar residue is subjected to high-temperature, high-pressure/vacuum fractional rectification in a strong alkali solution, and a reduced organic product is obtained under the coexistence of a high-boiling-point organic solvent and a reducing agent.

Chenshuxia et al disclose in CN100400520C a distillation-reduction method for "extracting methyl o-phenylenediamine from TDI organic residue and synthesizing TTA".

Under the coexistence of high boiling point organic solvent, adding reducing agent sodium nitrite in the rectification process to obtain methyl o-phenylenediamine (TDA), and finally obtaining methyl benzotriazole sodium salt (TTA). The method comprises the steps of extracting methyl o-phenylenediamine from TDI organic residues by adopting a dissolving and vacuum extraction rectification method under certain temperature and pressure by taking TDI organic residue as a raw material, and synthesizing the methyl o-phenylenediamine and excessive sodium nitrite solution into a tolyltriazole (TTA) product in one step by adopting medium pressure. The material temperature in the TDI organic residue purification and refining process is 160-190 ℃, the vacuum degree in a reaction kettle is 50-380 Pa, and the TTA synthesis process is carried out for 3.5-4 hours at the temperature of 250 +/-20 ℃ and the pressure of 4.6-5.2 MPa under constant temperature and pressure.

Liujun uses TDI residues to prepare 2, 4-diaminotoluene through normal-pressure hydrolysis (China capital, 9 months 2012, total 273 th period, 284-285). The method comprises the following specific steps: adding the residue into high boiling point solvent, adding into dry three-neck round-bottom flask together with NaOH solution, heating to set temperature with electronic universal furnace, refluxing at constant temperature, and mechanically stirring. And after the reaction is finished, carrying out suction filtration on the reaction liquid, extracting the filtrate by using extract liquor, then carrying out reduced pressure distillation on the extract liquor to obtain light yellow oily liquid, and cooling to obtain a solid hydrolysis product 2, 4-diaminotoluene.

Zhang Lingming et al proposed "analysis and utilization of heavy oil agent TDI tar residue" (development of chemical industry, vol. 34, No. 3, 863-866, 2015). TDI is prepared by reacting diethyl isophthalate (DEIP) dissolved in a heavy oil agent with excess phosgene. The tar residue contained polymerized biuret and approximately 50% DEIP, both of which could be hydrolyzed. The method comprises the following specific steps of hydrolyzing the residue in an alkaline system (NaOH solution) at a low temperature for a short time to generate sodium isophthalate, adjusting the pH of the solution to be =2 by hydrochloric acid to generate isophthalic acid which is slightly soluble in water, and separating out the isophthalic acid in the solution to form precipitate to obtain the finished isophthalic acid.

The mixed combustion method of tar residue and heavy oil. The method utilizes the combustible characteristics of small molecular substances such as carbon, hydrogen, oxygen and the like in the residues, and achieves the final purposes of obtaining a large amount of heat by combustion and reducing and disposing the residues. The method has the advantages of obvious advantages, less equipment investment, simple process operation and large heat recovery. The disadvantages are: unable to recover useful substances, large pollution discharge and large residual secondary residue.

It is also not uncommon to report the use of alcoholysis reactions to convert lipid materials into fuel oil fuels. For example, the application of wanlian mandarin and the like in ' supercritical methanol in chemical reaction ' (chemical development, 5 months 2010, 796-802.) mentions that ' preparation of … … Deimrbas of 3.2 biodiesel respectively has excellent comprehensive performance on biodiesel prepared under supercritical low-carbon alcohol based on different raw material grease, and … … indicates that the biodiesel prepared under supercritical low-carbon alcohol has excellent comprehensive performance. "

The Genistein et al reports in "research on degradation mechanism of polybutylene terephthalate in supercritical methanol" (proceedings of chemical engineering of colleges and universities, 2 months in 2007, 48-53): "complete degradation of polybutylene terephthalate (PBT), the main products of which are dimethyl terephthalate (DMT) and Butanediol (BG), can be achieved in the supercritical region".

Mongolian stars are disclosed in "energy saving alcohol based fuels" (CN 106281485A): 62 to 86 parts of methanol, 12 to 24 parts of diesel oil, 0.6 to 1.8 parts of cyclohexyl nitrate, 0.5 to 1.7 parts of isooctyl nitrate, 0.4 to 1.6 parts of 4-tert-butyl-2, 6-diisopropyl phenol, 0.3 to 0.9 part of 2, 4-dimethyl aniline, 0.1 to 0.7 part of tri-tert-butyl phosphate, 0.01 to 0.07 part of glycerol, 0.03 to 0.15 part of combustion accelerator and 0.1 to 1.3 parts of cleaning agent. The energy-saving alcohol-based fuel has the effects of resisting oxidation, supporting combustion, resisting corrosion, resisting freezing, cleaning, improving the cetane number and the like. "

Xiaolonggen disclosed in ' an environment-friendly alcohol-based fuel and a preparation method thereof ' (CN 108707485A) ' methanol 80-85%, methyl tert-butyl ether 4-7%, water 4-7%, sec-butyl acetate 2-5%, triethylamine 1-4%, hydrogen peroxide 0.5-2%, glycine complex iron 0.5-2%, and sodium hydroxide 0.5-2%. … … the alcohol-based fuel of the present invention has a higher heating value and a lower sulfur content than existing alcohol-based fuels. "

The method has the advantages that: the solid waste is recycled and the utilization efficiency is reduced. And (3) digesting TDI tar residue particles, and recovering low-boiling-point micromolecule organic matters and related inorganic matters. The method has the advantages of simple process, simple and convenient operation, easily controlled conditions, less equipment investment and low recovery cost. The liquid fuel has high heat value and small risk of secondary pollution caused by the emission of combustion products. Is beneficial to energy conservation, emission reduction and environmental protection.

Disclosure of Invention

In order to overcome the defects of the prior art and more effectively realize the aims of recycling, reducing and harmlessly disposing TDI tar residues, the invention provides a method for preparing liquid fuel by using TDI tar residues,

the technical scheme of the invention is as follows: a method for preparing liquid fuel by using TDI tar residues comprises the following steps:

step one), mechanically grinding a TDI tar residue solid particle raw material into powder; weighing the ground TDI tar residue powder, placing the powder in a high-temperature high-pressure reaction kettle with a stirring device, adding a low-boiling-point polar solvent according to a solid-liquid ratio of 1: 1-20 kg/L, and mixing and stirring uniformly to obtain a solid-liquid mixture containing TDI tar residue;

step two), heating the reaction kettle containing the solid-liquid mixture from room temperature to 100-350 ℃, keeping the pressure at 2-12 MPa, keeping the temperature for 15-120 min for carrying out digestion reaction to obtain a digested solid-liquid mixture, and reducing the pressure and cooling to normal temperature and normal pressure;

step three), carrying out solid-liquid separation on the digestion solid-liquid mixture to respectively obtain digestion filtrate and digestion solid residue; washing and digesting the residual residues by using a low-boiling-point polar solvent, and combining the residual residues with the digestion filtrate to obtain total digestion filtrate;

step four), adding the mixed fuel accelerant into the total digestion filtrate, and uniformly stirring to obtain a liquid fuel product.

The further improvement is that the low-boiling-point polar solvent is a mixture of one or more solvents, the polar parameter of the solvent is 2-8, and the boiling point is 60-160 ℃;

in a further refinement, the low boiling polar solvent comprises: the ratio of carbon to hydrogen to oxygen atoms in the structure is 1-8: 4-10: 1-2 of alcohols, ketones, esters and aromatic hydrocarbons or derivatives.

In a further improvement, the method also comprises a fourth step of adding a fuel accelerant into the digestion total filtrate and uniformly stirring; the fuel accelerant is one or a mixture of more of ferrocene, acetyl ferrocene, tert-butyl ferrocene, vinyl ferrocene and ferrocene derivatives thereof.

Drawings

The invention will be further described with reference to the following examples with reference to the accompanying drawings.

FIG. 1 is a process flow diagram of the present invention.

Detailed Description

The first method is implemented.

Mechanically grinding a TDI tar residue solid raw material into TDI tar residue powder with the particle size of 80-200 meshes; weighing a proper amount of ground TDI tar residue powder, placing the powder into a high-temperature high-pressure reaction kettle with a stirring device, adding a methanol solvent according to a solid-liquid ratio of 1:10 (mass: volume ratio, kilogram: liter), mixing and uniformly stirring to obtain a solid-liquid mixture 1 containing TDI tar residue. And (3) heating the high-temperature high-pressure reaction kettle containing the solid-liquid mixture 1 from room temperature to 230-250 ℃, keeping the pressure at 4-6 MPa, and keeping the temperature for 15-120 min for carrying out digestion reaction to obtain a digestion solid-liquid mixture 2. And closing the switch of the high-temperature high-pressure reaction kettle, reducing the pressure and cooling to normal temperature and normal pressure.

And carrying out solid-liquid separation on the digestion solid-liquid mixture 2 to respectively obtain a digestion filtrate and a digestion solid residue. And washing and digesting the solid residue 3-5 times by using a small amount of the methanol solvent. And (5) digesting the solid residue for later use. And combining the washing filtrate obtained each time with the digestion filtrate to obtain the total filtrate. Adding ferrocene into the total filtrate according to the mass percent of 1:5, and uniformly stirring to prepare the liquid fuel.

And implementing the second method.

Mechanically grinding a TDI tar residue solid raw material into TDI tar residue powder with the particle size of 80-200 meshes; weighing a proper amount of ground TDI tar residue powder, placing the powder into a high-temperature high-pressure reaction kettle with a stirring device, adding an isopropanol solvent according to a solid-liquid ratio of 1:10 (mass: volume ratio, kilogram: liter), mixing and uniformly stirring to obtain a solid-liquid mixture 1 containing TDI tar residue. And (3) heating the high-temperature high-pressure reaction kettle containing the solid-liquid mixture 1 from room temperature to 240-260 ℃, keeping the pressure at 4-6 MPa, and keeping the temperature for 15-120 min for carrying out digestion reaction to obtain a digestion solid-liquid mixture 2. And closing the switch of the high-temperature high-pressure reaction kettle, reducing the pressure and cooling to normal temperature and normal pressure.

And carrying out solid-liquid separation on the digestion solid-liquid mixture 2 to respectively obtain a digestion filtrate and a digestion solid residue. And washing and digesting the solid residue 3-5 times by using a small amount of isopropanol solvent. And (5) digesting the solid residue for later use. And combining the washing filtrate obtained each time with the digestion filtrate to obtain the total filtrate. And adding an acetyl ferrocene additive into the total filtrate according to the mass percent of 1:5, and uniformly stirring to prepare the liquid fuel.

And (5) implementing the third method.

Mechanically grinding the TDI tar residue solid raw material into TDI tar residue powder with the particle size of 200 meshes; weighing a proper amount of ground TDI tar residue powder, placing the powder into a high-temperature high-pressure reaction kettle with a stirring device, adding an acetic acid solvent according to a solid-liquid ratio of 1:10 (mass: volume ratio, kilogram: liter), mixing and uniformly stirring to obtain a solid-liquid mixture 1 containing TDI tar residue. And (3) heating the high-temperature high-pressure reaction kettle containing the solid-liquid mixture 1 from room temperature to 240-260 ℃, keeping the pressure at 3-5 MPa, and keeping the temperature for 15-120 min for carrying out digestion reaction to obtain a digestion solid-liquid mixture 2. And closing the switch of the high-temperature high-pressure reaction kettle, reducing the pressure and cooling to normal temperature and normal pressure.

And carrying out solid-liquid separation on the digestion solid-liquid mixture 2 to respectively obtain a digestion filtrate and a digestion solid residue. And washing and digesting the solid residue 3-5 times by using a small amount of the acetic acid solvent. And (5) digesting the solid residue for later use. And combining the washing filtrate obtained each time with the digestion filtrate to obtain the total filtrate. Adding ferrocene into the total filtrate according to the mass percent of 1:5, and uniformly stirring to prepare the liquid fuel.

The above description is only an example of the preferred embodiment of the present invention, and is not intended to limit the scope of the present invention. Any modification, equivalent replacement, and improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preparing liquid fuel by using TDI tar residues is characterized by comprising the following steps:

step one), grinding a TDI tar residue solid raw material into powder; weighing the ground TDI tar residue powder, placing the powder in a high-temperature high-pressure reaction kettle with a stirring device, adding a low-boiling-point polar solvent according to a solid-liquid ratio of 1: 1-20 kg/L, and mixing and uniformly stirring to obtain a solid-liquid mixture A containing TDI tar residue; the low-boiling-point polar solvent is one or a mixture of a plurality of solvents, the polar parameter of the solvent is 2-8, and the boiling point is 60-160 ℃;

the low-boiling polar solvent includes: the atomic ratio of the elements of carbon, oxygen and hydrogen is 1-8: 4-10: 1-2 of alcohols, ketones, esters and aromatic hydrocarbons and derivatives thereof;

step two), heating a reaction kettle containing the solid-liquid mixture A from room temperature to 100-350 ℃, keeping the pressure at 2-12 MPa, keeping the temperature for 120min for carrying out digestion reaction to obtain a digestion solid-liquid mixture B, and reducing the pressure and cooling to normal temperature and normal pressure;

step three), carrying out solid-liquid separation on the digestion solid-liquid mixture B to respectively obtain digestion filtrate and solid residues; and washing the digestion solid residue by using the low-boiling-point polar solvent, and combining the digestion solid residue with the digestion filtrate to obtain total digestion filtrate which can be used as fuel.

2. The method for preparing liquid fuel by using TDI tar residues as claimed in claim 1, wherein: the method also comprises

Step four), adding a fuel accelerant into the total digestion filtrate, and uniformly stirring; the fuel accelerant is one or a mixture of more of ferrocene, acetyl ferrocene, tert-butyl ferrocene and vinyl ferrocene.