Preparation method for synthesizing biological alkyl diesel oil from waste engine oil

Abstract

According to the preparation method for synthesizing the biological alkyl diesel oil from the waste engine oil, mixed fatty acid methyl ester biodiesel prepared from kitchen waste oil and lubricating oil base oil prepared from the waste engine oil are used as raw materials and are subjected to catalytic hydrogenation and post-treatment in a fixed bed hydrogenation reactor; and converting the mixed fatty acid methyl ester biodiesel and the lubricant base oil into the biological alkyl diesel. The preparation method for synthesizing the biological alkyl diesel oil from the waste engine oil is simple and convenient, the biological alkyl diesel oil is good in compatibility, high in calorific value, low in melting point and good in fluidity, resource utilization of kitchen waste grease and the waste engine oil is achieved, and the good market space is achieved.

Description

Technical Field

[0001] The invention relates to a method for preparing bio-alkyl diesel synthesized from waste engine oil, and specifically belongs to the technical field of new energy. Background Art

[0002] Currently, biomass diesel produced from waste cooking oil can only be mixed with automotive "O" diesel at a rate of 5-7% due to its low calorific value, high melting point and poor fluidity. The two also have poor miscibility and the product is foggy and opaque, making it difficult to promote biomass diesel.

[0003] On the other hand, waste oil is a complex mixture of various substances. It mainly comes from the lubricating oil that must be replaced after aging and deterioration to a certain extent during the use of various machinery, vehicles, and ships. The output accounts for about 20% of the total output of petroleum products. Waste oil is often discarded at will, causing great harm to the environment and human health. If it is not properly disposed of, whether it is poured into the sewer, poured into the ground soil, or poured into the trash can, it will cause serious pollution to the environment. A large barrel (200L) of waste oil flowing into the water area can pollute nearly 3 to 5 square kilometers of water surface, which will have a huge impact on the environment and cause immeasurable losses. The disadvantages of the waste oil refining process technology are that the cetane number is less than 40, the combustion value is about 7500 kcal, and the heavy fraction has a high color and is opaque, the recovery rate is low, the production process is complicated, and the "distillation-pickling-alkali refining-white clay" process will produce a large amount of waste acid, waste water, waste gas and waste residue during the production process, causing serious secondary pollution. With the development of the economy and the improvement of people's environmental awareness, the environmental protection treatment of waste oil has become an important field, bringing new challenges and opportunities to the environmental protection industry. There is an urgent need for recycling and reuse technology to reduce resource waste and ensure human health and environmental safety.

[0004] In view of the above situation, the present invention uses mixed fatty acid methyl ester biodiesel produced from waste cooking oil as raw material and pre-treated waste engine oil as mixed oil raw material, which is converted into bio-alkyl diesel through hydrodeoxygenation. Its quality is better than national standard "O" diesel, which opens up a new way to utilize waste oil, turning it into treasure, serving the society, and fundamentally solving the hazards of waste cooking oil and waste engine oil. Summary of the invention

[0005] In view of the above situation, the present invention provides a method for preparing bio-alkyl diesel synthesized from waste engine oil, so as to achieve the purpose of resource utilization of waste engine oil.

[0006] The present invention provides a method for preparing bio-alkyl diesel synthesized from waste engine oil, comprising the following steps: Step 1: Using waste engine oil as raw material, removing low-boiling substances, additives and free acids therein by flash dehydration and impurity removal, and falling film distillation, and then filtering to obtain lubricating oil base oil; Step 2: Mix the mixed fatty acid methyl ester biodiesel and the lubricating oil base oil in a mass ratio of 18:94, and then perform physical circulation mixing for 60 minutes at a temperature of 60° C. through a pipeline pump to obtain a mixed oil product; Step 3: After pre-sulfurizing the XF-YHX-3 hydrogenation catalyst, the mixed oil product is subjected to catalytic hydrogenation reforming in a fixed bed hydrogenation reactor; Step 4: Post-treatment of hydrogenation product: After catalytic hydrogenation, the reaction effluent from the fixed bed hydrogenation reactor is heat exchanged in a heat exchanger, and then cooled by an air cooler and a water cooler, separated into three phases of oil, gas and water by a high-pressure separator, and flash dehydrated to obtain bio-alkyl diesel; wherein the pressure of the flash dehydration is negative pressure -0.098Mpa and the temperature is 90°C.

[0007] The acid value of the mixed fatty acid methyl ester biodiesel is ≤0.5.

[0008] The XF-YHX-3 hydrogenation catalyst is made of Ni, Mo and Co oxides as raw materials and Al2O3 as a carrier. It is pressed into a solid strip shape with a specification of Φ0.2cm×3cm and then calcined at 450°C for 6h. The mass ratio of Ni:Mo:Co:Al2O3 in the catalyst is 18:16:10:56.

[0009] The fixed bed reactor is made of 316L stainless steel, with a height-to-diameter ratio (H / D) ≥ 9. Eight temperature measuring points are evenly distributed from the bottom to the top of the catalyst bed and are DCS controlled. The working pressure is 5 MPa and the working temperature is 550°C.

[0010] The hydrogenation process is as follows: the inlet and outlet temperatures of the fixed bed hydrogenation reactor are 280°C and 350°C respectively, and the hydrogenation space velocity is 1.0h -1 , the volume ratio of hydrogen to oil is 1000:1.

[0011] The pre-sulfurization is to increase the pressure of the catalyst bed to 2Mpa, and the sulfurizing agent carbon disulfide is heated for 0.5h. -1 The space velocity was fed, the ratio of hydrogen to the sulfiding agent carbon disulfide was 1000:1 (V / V), the temperature in the catalyst bed system was increased to 170°C at a rate of 10°C / h and kept at a constant temperature for 2h, then continued to be increased to 230°C at a rate of 10°C / h and kept at a constant temperature for 8h, then continued to be increased to 320°C at a rate of 10°C / h and kept at a constant temperature for 8h, maintained the hydrogen flow rate, stopped feeding the sulfiding agent carbon disulfide, and after the catalyst bed temperature was reduced to 200°C, the pre-sulfurization of the catalyst was completed.

[0012] The invention has the following beneficial effects: the bio-alkyl diesel synthesized by using mixed fatty acid methyl ester biodiesel and waste engine oil as raw materials overcomes the problem of poor compatibility between biodiesel and gasoline and diesel produced by regenerating waste engine oil; the bio-alkyl diesel overcomes the problem that single biomass diesel has low calorific value, high melting point, poor fluidity, poor miscibility with vehicle "O" diesel, and the product is foggy and opaque, which makes biomass diesel difficult to promote; the bio-alkyl diesel overcomes the problem that single waste engine oil is refined into diesel with low cetane number and low combustion value, high chroma and opacity of heavy fraction, low recovery rate, and a large amount of waste acid, waste water, waste gas and waste residue are generated, causing serious secondary pollution; the bio-alkyl fuel synthesized by using mixed fatty acid methyl ester biodiesel prepared from waste cooking oil and waste engine oil, which fully utilizes waste resources, effectively eliminates the harm caused by waste cooking oil to human health and the significant impact of waste engine oil on the environment; compared with fossil No. 0 diesel, the cetane number and calorific value of bio-alkyl diesel are higher than fossil diesel; bio-alkyl diesel belongs to high-quality green and environmentally friendly new energy, and will become a forced product in the fuel market. The preparation method of synthesizing bio-alkyl diesel from waste engine oil of the present invention is simple, and the bio-alkyl diesel has good compatibility, high calorific value, low melting point and good fluidity, thus realizing the resource utilization of waste kitchen grease and waste engine oil, and having a good market space. DETAILED DESCRIPTION

[0014] Example 1 Preparation and loading of XF-YHX-3 hydrogenation catalyst Using Ni, Mo, and Co as raw materials and Al2O3 as a carrier, the catalyst XF-YHX-3 was prepared by pressing the three non-precious metal oxides into a solid strip with a size of Φ0.2cm×3cm and calcining it at 450℃ for 6h. The mass ratio of Ni∶Mo∶Co∶Al2O3 is 18:16:10:56.

[0015] The fixed bed hydrogenation reactor is made of 316L stainless steel, with a reactor height of h=11m and a diameter of Φ=60cm. There are 8 temperature measurement points evenly distributed from the bottom to the top of the catalyst bed, and it is controlled by DCS, with a working pressure of 5Mpa and a working temperature of 550℃. The XF-YHX-3 hydrogenation catalyst is loaded into the middle of the fixed bed hydrogenation reactor, and the upper and lower beds of the catalyst bed are respectively filled with 3mm, 6mm, 12mm and 18mm porcelain balls. The height of the upper and lower beds is 50cm each to ensure the stability of the catalyst bed when the pressure fluctuates. A quenching hydrogen facility is provided between the beds.

[0016] Example 2 Catalyst presulfiding After loading, the catalyst was pre-sulfurized. The pressure of the catalyst bed system was raised to 2 MPa, and the sulfurizing agent carbon disulfide was added for 0.5 h.-1 The space velocity was fed, the ratio of hydrogen to the sulfiding agent carbon disulfide was 1000:1 (V / V), the temperature in the catalyst bed system was increased to 170°C at a rate of 10°C / h and kept at a constant temperature for 2h, then continued to be increased to 230°C at a rate of 10°C / h and kept at a constant temperature for 8h, then continued to be increased to 320°C at a rate of 10°C / h and kept at a constant temperature for 8h, maintained the hydrogen flow rate, stopped the sulfiding agent feeding, and after the catalyst bed temperature was reduced to 200°C, the pre-sulfurization of the catalyst was completed.

[0017] Example 3 Preparation of Bio-alkyl Diesel Step 1: Pretreatment of waste oil After the waste oil is dehydrated by the flash evaporation system and the low-boiling substances, additives and free acids are removed by falling film distillation, it is filtered through a super-strong membrane filter to obtain lubricating oil base oil. Among them, the working pressure of the flash evaporation system is negative pressure -0.098Mpa and the temperature is 90℃; the working pressure of the molecular distillation system is negative pressure -0.098Mpa and the temperature is 180℃. After filtering, the lubricating oil base oil is obtained.

[0018] Step 2: Blending of FAME biodiesel and lubricant base oil The mixed fatty acid methyl ester biodiesel prepared from waste cooking oil and lubricating base oil were mixed in a mass ratio of 18:94, heated to 60°C in a mixed oil storage tank, and circulated for 60 minutes through a pipeline pump for physical mixing to obtain a mixed oil product.

[0019] Step 3: Catalytic hydrogenation of the oil mixture The mixed oil product is heat exchanged with the reaction effluent and then mixed with hydrogen. Then, it is heated to the reaction temperature in the heating furnace and enters the fixed bed hydrogenation reactor. The hydrogenation pressure of the fixed bed hydrogenation reactor is 2.5Mpa, the inlet temperature is 280℃, and the outlet temperature is 350℃. The reaction temperature is adjusted by feed heating and quenching hydrogen facilities in the fixed bed hydrogenation reactor. The hydrogenation reaction space velocity is 1.0 h -1 , the reaction hydrogen-to-oil ratio (v / v) is 1000:1, and catalytic hydrogenation is carried out using XF-YHX-3 hydrogenation catalyst.

[0020] Step 4: Post-treatment of hydrogenation products After catalytic hydrogenation, the reaction effluent from the fixed bed hydrogenation reactor is successively heat-exchanged with the reaction feed, low-fraction oil (semi-finished product), mixed fatty acid methyl ester biodiesel and waste oil in the heat exchanger, and then cooled to 45°C through an air cooler and a water cooler, and then enters the high-pressure separator for oil, gas and water three-phase separation.

[0021] The high-fraction gas (circulating hydrogen) produced is separated by the liquid separator and then enters the circulating hydrogen compressor for pressure increase, and then is divided into two paths: one path enters the reactor as quenching hydrogen; the other path is mixed with the new hydrogen from the hydrogen compressor and then mixed with the mixed oil as reaction feed; the wastewater produced is discharged from the bottom of the high-pressure separator to the acidic water stripping device for treatment; the reaction effluent after three-phase separation enters the flash evaporation system for dehydration to obtain bio-alkyl diesel. The working pressure of the flash evaporation system is negative pressure -0.098Mpa and the temperature is 90℃.

[0022] After hydrogenation treatment, the nitrogen and oxygen content in the mixed fatty acid methyl ester biodiesel is removed, the double bonds are saturated and converted into bio-alkanes, the sulfur, iron ions and other metal impurities and odor in the lubricating oil base oil are removed, the color and stability of the oil are improved, and the physical and chemical indicators of the obtained bio-alkyl diesel are as follows: .

Claims

1. A method for preparing bio-alkyl diesel synthesized from waste engine oil, characterized in that: The preparation method comprises the following steps: Step 1: Using waste engine oil as raw material, removing low-boiling substances, additives and free acids therein by flash dehydration and impurity removal, and falling film distillation, and then filtering to obtain lubricating oil base oil; Step 2: Mix the mixed fatty acid methyl ester biodiesel and the lubricating oil base oil in a mass ratio of 18:94, and then perform physical circulation mixing for 60 minutes at a temperature of 60° C. through a pipeline pump to obtain a mixed oil product; Step 3: After pre-sulfurizing the XF-YHX-3 hydrogenation catalyst, the mixed oil product is subjected to catalytic hydrogenation reforming in a fixed bed hydrogenation reactor; Step 4: Post-treatment of hydrogenation product: After catalytic hydrogenation, the reaction effluent from the fixed bed hydrogenation reactor is heat exchanged in a heat exchanger, and then cooled by an air cooler and a water cooler, separated into three phases of oil, gas and water by a high-pressure separator, and flash dehydrated to obtain bio-alkyl diesel; wherein the pressure of the flash dehydration is negative pressure -0.098Mpa and the temperature is 90°C.

2. The method for preparing bio-alkyl diesel from waste engine oil according to claim 1, characterized in that: The acid value of the mixed fatty acid methyl ester biodiesel is ≤0.

5.

3. The method for preparing bio-alkyl diesel from waste engine oil according to claim 1, characterized in that: The XF-YHX-3 hydrogenation catalyst is made of Ni, Mo and Co oxides as raw materials and Al2O3 as a carrier. It is pressed into a solid strip shape with a specification of Φ0.2cm×3cm and then calcined at 450°C for 6h. The mass ratio of Ni:Mo:Co:Al2O3 in the catalyst is 18:16:10:

56.

4. The method for preparing bio-alkyl diesel from waste engine oil according to claim 1, characterized in that: The fixed bed reactor is made of 316L stainless steel, with a height-to-diameter ratio (H / D) ≥ 9. Eight temperature measuring points are evenly distributed from the bottom to the top of the catalyst bed and are DCS controlled. The working pressure is 5 MPa and the working temperature is 550°C.

5. The method for preparing bio-alkyl diesel from waste engine oil according to claim 1, characterized in that: The hydrogenation process is as follows: the inlet and outlet temperatures of the fixed bed hydrogenation reactor are 280°C and 350°C respectively, and the hydrogenation space velocity is 1.0h -1 , the volume ratio of hydrogen to oil is 1000:

1.

6. The method for preparing bio-alkyl diesel from waste engine oil according to claim 1, characterized in that: The pre-sulfurization is to increase the pressure of the catalyst bed to 2Mpa, and the sulfurizing agent carbon disulfide is heated for 0.5h. -1 The space velocity was fed, the ratio of hydrogen to the sulfiding agent carbon disulfide was 1000:1 (V / V), the temperature in the catalyst bed system was increased to 170°C at a rate of 10°C / h and kept at a constant temperature for 2h, then continued to be increased to 230°C at a rate of 10°C / h and kept at a constant temperature for 8h, then continued to be increased to 320°C at a rate of 10°C / h and kept at a constant temperature for 8h, maintained the hydrogen flow rate, stopped feeding the sulfiding agent carbon disulfide, and after the catalyst bed temperature was reduced to 200°C, the pre-sulfurization of the catalyst was completed.