Preparation method of alcohol-based oxygen-containing fuel additive
By introducing multi-level porous molecular sieves and potassium alkoxide active components into carbonate fuel additives, the problem of low boiling point of carbonate additives has been solved, enabling the preparation of high-boiling-point alcohol-based oxygenated fuels and improving combustion performance and safety.
Patent Information
- Application Number
- CN202511751772.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-11-26
- Publication Date
- 2026-03-13
AI Technical Summary
Existing carbonate-based fuel additives have low boiling points and are easily volatile, affecting the safety and combustion performance of diesel fuel. Furthermore, butyl carbonate is difficult to synthesize and has low catalytic activity.
Using a multi-level porous molecular sieve as a carrier, potassium alkoxide active components and amphiphilic molecular linkers are introduced, and methyl butyl carbonate and dibutyl carbonate are generated through transesterification reaction to prepare a high-boiling-point alcohol-based oxygenated fuel additive.
It increases the oxygen content and combustion performance of fuel, reduces volatilization loss, enhances fuel stability and safety, and lowers costs.
Abstract
Description
Technical Field
[0001] This invention belongs to the field of fuel additive preparation, and specifically relates to a method for preparing an alcohol-based oxygenated fuel additive. Background Technology
[0002] Alcohol-based oxygenated fuels, as a cleaner alternative to diesel engine fuels, have the advantages of abundant raw material sources and superior emission performance. Applying alcohol-based oxygenated fuels as diesel additives or partial substitutes can reduce exhaust emissions and improve combustion efficiency in diesel engines; therefore, research on oxygenated fuels has attracted considerable attention.
[0003] Research on the application of alcohol-based oxygenated fuels in internal combustion engines has a long history, but past research has focused on energy substitution rather than combustion emission characteristics. Since the 1990s, global energy consumption has increased dramatically, and limited petroleum resources have struggled to meet energy demands; meanwhile, the increasing number of vehicles has led to a surge in harmful emissions. Therefore, from the perspectives of energy security and environmental protection, countries have begun to seek clean alternative energy sources. Alcohol-based oxygenated fuels can reduce harmful emissions from diesel engines, especially particulate matter. Furthermore, alcohol-based oxygenated fuels derived from biomass are renewable energy sources and do not increase net CO2 emissions during the natural energy cycle of biofuels, making them a promising clean energy fuel.
[0004] Oxygenated fuels are fuels that provide additional oxygen to diesel engines, allowing for more complete combustion. Oxygenated fuels can reduce emissions of harmful substances such as unburned HC, CO, PM, and soot from diesel engines, making the use of oxygenated fuels one of the effective technologies for controlling diesel engine emissions.
[0005] Oxygenated diesel fuel is essentially a mixture of conventional diesel fuel and one or more oxygen-containing organic compounds (such as biodiesel, dimethoxymethane, dimethyl carbonate, etc.). Its core advantage stems from a simple chemical principle: introducing oxygen atoms at the molecular level, thereby profoundly altering the combustion behavior of the fuel within the engine cylinder.
[0006] The most significant and widely proven advantage lies in the comprehensive improvement of emission characteristics. After high-pressure fuel injection, traditional diesel engines create areas of excessively high fuel concentration and localized oxygen deficiency, which are breeding grounds for soot (black smoke) and particulate matter. The introduction of oxygenated fuel is equivalent to having a "built-in" oxygen supply within the fuel itself. When these fuel droplets evaporate and decompose in the combustion chamber, the released oxygen atoms can directly participate in and promote the oxidation process of intermediate products, thus effectively suppressing soot particle formation in its initial stages. Numerous studies have shown that even adding only a small amount (such as 10%-20%) of oxygenated components can reduce engine soot emissions by as much as 30% to 50%, or even more. This is a landmark achievement in solving the persistent problem of black smoke from diesel vehicles.
[0007] Besides reducing carbon emissions, the complete and uniform combustion of fuel brings a series of positive chain reactions. First, the emission of carbon monoxide, the main gaseous pollutant produced by incomplete combustion, is significantly reduced due to improved combustion conditions. Second, unburned hydrocarbons are also reduced, as fuel that might have otherwise missed the flame or adhered to cold walls and failed to participate in the reaction now has a greater chance of being completely oxidized in an oxygen-rich environment. Third, this improvement in combustion efficiency directly translates into increased energy utilization, meaning more fuel chemical energy is effectively converted into work, thereby improving engine thermal efficiency under certain conditions. Although oxygenated fuels themselves may have a slightly lower energy density, this combustion optimization effect often partially or even completely offsets the energy loss they cause.
[0008] Furthermore, oxygenated diesel fuel offers dual benefits for the environment and sustainable development. As it can partially replace fossil fuels, it helps reduce our dependence on them. If oxygenated fuels are derived from biofuels, the carbon footprint over the entire fuel lifecycle is reduced because plants absorb carbon dioxide during their growth. Simultaneously, certain oxygenated components (such as alcohols and ethers) have high octane numbers and latent heats of vaporization, which effectively lower combustion temperatures and have the potential benefit of suppressing the formation of another major pollutant—nitrogen oxides.
[0009] However, oxygenated diesel also faces challenges related to energy density, material compatibility, cost, and the potential increase in nitrogen oxide emissions. Undoubtedly, its enormous potential in addressing the most intractable particulate pollution problem in diesel engines makes it a highly valuable and promising research direction in the current transition of internal combustion engine technology towards cleaner and more efficient processes.
[0010] Currently, many types of oxygenated fuels for diesel engines are under research, commonly including vegetable oils and their esterified fuels, biomass pyrolysis fuels, alcohol fuels, and dimethyl ether. Carbonates are an excellent class of alcohol-based oxygenated fuel additives, significantly increasing fuel oxygen content and improving combustion. They are also environmentally friendly solvents due to their structure containing multiple chemical groups and their reactive chemical properties. Therefore, carbonate additives have a promising market prospect.
[0011] However, dimethyl carbonate has a boiling point of 90℃, methyl ethyl carbonate 107℃, and diethyl carbonate 126℃. These carbonate additives all have boiling points below 130℃, which is far below the boiling range of diesel fuel (160–350℃). These additives are prone to volatilization and loss, and they also lower the flash point of diesel fuel, significantly impacting its safety. Therefore, researching and developing synthetic methods for oxygen-containing component additives with high molecular weight and high boiling points is of great significance.
[0012] Butanol is relatively readily available, inexpensive, and widely sourced, and dibutyl carbonate has a boiling point of 164℃, which is close to the boiling range of diesel fuel, making it very suitable as a diesel fuel additive. Therefore, research on the synthesis of dibutyl carbonate is of great significance. However, the synthesis of dibutyl carbonate is difficult due to the low reactivity of butanol. Thus, developing supported catalysts with high catalytic activity for the synthesis of dibutyl carbonate is of great importance. Summary of the Invention
[0013] This invention develops a dedicated catalyst and preparation process for alcohol-based oxygenated fuel additives. The invention mainly relates to the preparation method of catalysts for the synthesis of monobutyl carbonate and dibutyl carbonate. This catalyst uses a hierarchical porous molecular sieve as a support and introduces a potassium alkoxide active component and an amphiphilic linker. In application, this catalyst catalyzes the transesterification reaction of dimethyl carbonate and butanol, generating a reaction mixture mainly composed of methyl butyl carbonate and dibutyl carbonate. After fractionation, an alcohol-based oxygenated fuel additive with a suitable boiling point and significantly improved fuel oxygen content is obtained.
[0014] Step 1: The catalyst preparation method is as follows:
[0015] (1) Carrier preparation
[0016] In 250 ml of an aqueous solution containing 2 wt% sodium hydroxide, 25 g of tetrapropylammonium bromide and 2.7 g of aluminum sulfate were added. The mixture was stirred vigorously at room temperature until completely dissolved. Then, 157 g of 30% silica sol was added dropwise and stirred at room temperature for 2 h. Next, 8.8 g of 3-aminopropyltriethoxysilane was added dropwise and stirred in a water bath at 30 °C for 2 h. The mixture was then allowed to stand overnight at room temperature for aging. Subsequently, the solution was transferred to a crystallization vessel and heated to 160 °C at a rate of 2 °C / min, maintained for 48 h, and then cooled to room temperature at a rate of 0.5 °C / min. The mixture was removed, filtered to obtain a solid, and then washed with deionized water until the filtrate was neutral. The solid was dried in a vacuum drying oven (80 °C, 0.1 kPa) for 10 h and then calcined in a muffle furnace at 550 °C for 5 h to obtain a hierarchical porous molecular sieve support.
[0017] (2) Catalyst preparation
[0018] The prepared hierarchical porous molecular sieve support was ultrasonically impregnated with a linker and active component solution in a certain proportion. For every 8 hours of impregnation, ultrasonic assistance was performed for 30 minutes, for a total of 24 hours. After impregnation, the solid was vacuum dried at 110℃ for 2 hours, and then calcined at 550℃ in air atmosphere in a muffle furnace for 4 hours to obtain the catalyst.
[0019] The active component is one or more of potassium methoxide, potassium ethoxide, and potassium tert-butoxide, and the amount of the active component added is 0.1% to 5% of the carrier mass.
[0020] The binder is one or more of polyethylene glycol, polypropylene glycol, and cyclodextrin, and the amount added is determined according to the molar ratio of binder to active component of 1:1 to 10:1.
[0021] The second step is the preparation process of fuel additives:
[0022] Dimethyl carbonate and butanol were mixed and then reacted under the following conditions: temperature range: 70℃~120℃, molar ratio of dimethyl carbonate / butanol: 1:2~1:4, reaction time: 2~10h. After the reaction was completed, the reaction mixture was distilled and the fraction mixture above 140℃ was collected as a fuel additive.
[0023] Advantages of the present invention
[0024] A linker was added during the catalyst preparation process of this invention. The linker is a molecule with multiple active groups that can enhance the stability of the potassium alkoxide active component and increase its loading. The catalyst performance was evaluated using a batch reactor, with a focus on investigating the stability of the prepared catalyst in the transesterification reaction. Detailed Implementation
[0025] The technical content and effects of the present invention are further illustrated below with reference to embodiments, but this does not limit the scope of the present invention.
[0026] Example 1:
[0027] Step 1: The catalyst preparation method is as follows:
[0028] (1) Carrier preparation
[0029] In 250 ml of an aqueous solution containing 2 wt% sodium hydroxide, 25 g of tetrapropylammonium bromide and 2.7 g of aluminum sulfate were added. The mixture was stirred vigorously at room temperature until completely dissolved. Then, 157 g of 30% silica sol was added dropwise and stirred at room temperature for 2 h. Next, 8.8 g of 3-aminopropyltriethoxysilane was added dropwise and stirred in a water bath at 30 °C for 2 h. The mixture was then allowed to stand overnight at room temperature for aging. Subsequently, the solution was transferred to a crystallization vessel and heated to 160 °C at a rate of 2 °C / min, maintained for 48 h, and then cooled to room temperature at a rate of 0.5 °C / min. The mixture was removed, filtered to obtain a solid, and then washed with deionized water until the filtrate was neutral. The solid was dried in a vacuum drying oven (80 °C, 0.1 kPa) for 10 h and then calcined in a muffle furnace at 550 °C for 5 h to obtain a hierarchical porous molecular sieve support.
[0030] (2) Catalyst preparation
[0031] The prepared hierarchical porous molecular sieve support was ultrasonically impregnated with a linker and active component solution in a certain proportion. For every 8 hours of impregnation, ultrasonic assistance was performed for 30 minutes, for a total of 24 hours. After impregnation, the solid was vacuum dried at 110℃ for 2 hours, and then calcined at 550℃ in air atmosphere in a muffle furnace for 4 hours to obtain the catalyst.
[0032] The active component is one or more of potassium methoxide, potassium ethoxide, and potassium tert-butoxide, and the amount of the active component added is 0.5% of the carrier mass.
[0033] The binder is one or more of polyethylene glycol, polypropylene glycol, and cyclodextrin, and the amount added is determined according to the molar ratio of binder to active component of 1:2.
[0034] The second step is the preparation process of fuel additives:
[0035] Dimethyl carbonate and butanol were mixed and then reacted under the following conditions: temperature range: 70℃, molar ratio of dimethyl carbonate to butanol: 1:3, reaction time: 5h. After the reaction was completed, the resulting reaction mixture was distilled, and the fraction mixture above 140℃ was collected as a fuel additive.
[0036] Example 2:
[0037] Step 1: The catalyst preparation method is as follows:
[0038] (1) Carrier preparation
[0039] In 250 ml of an aqueous solution containing 2 wt% sodium hydroxide, 25 g of tetrapropylammonium bromide and 2.7 g of aluminum sulfate were added. The mixture was stirred vigorously at room temperature until completely dissolved. Then, 157 g of 30% silica sol was added dropwise and stirred at room temperature for 2 h. Next, 8.8 g of 3-aminopropyltriethoxysilane was added dropwise and stirred in a water bath at 30 °C for 2 h. The mixture was then allowed to stand overnight at room temperature for aging. Subsequently, the solution was transferred to a crystallization vessel and heated to 160 °C at a rate of 2 °C / min, maintained for 48 h, and then cooled to room temperature at a rate of 0.5 °C / min. The mixture was removed, filtered to obtain a solid, and then washed with deionized water until the filtrate was neutral. The solid was dried in a vacuum drying oven (80 °C, 0.1 kPa) for 10 h and then calcined in a muffle furnace at 550 °C for 5 h to obtain a hierarchical porous molecular sieve support.
[0040] (2) Catalyst preparation
[0041] The prepared hierarchical porous molecular sieve support was ultrasonically impregnated with a linker and active component solution in a certain proportion. For every 8 hours of impregnation, ultrasonic assistance was performed for 30 minutes, for a total of 24 hours. After impregnation, the solid was vacuum dried at 110℃ for 2 hours, and then calcined at 550℃ in air atmosphere in a muffle furnace for 4 hours to obtain the catalyst.
[0042] The active component is one or more of potassium methoxide, potassium ethoxide, and potassium tert-butoxide, and the amount of the active component added is 1% of the carrier mass.
[0043] The binder is one or more of polyethylene glycol, polypropylene glycol, and cyclodextrin, and the amount added is determined according to the molar ratio of binder to active component of 3:1.
[0044] The second step is the preparation process of fuel additives:
[0045] Dimethyl carbonate and butanol were mixed and then reacted under the following conditions: temperature range: 80℃, molar ratio of dimethyl carbonate to butanol: 1:4, reaction time: 10h. After the reaction was completed, the resulting reaction mixture was distilled, and the fraction mixture above 140℃ was collected as a fuel additive.
[0046] Example 3:
[0047] Step 1: The catalyst preparation method is as follows:
[0048] (1) Carrier preparation
[0049] In 250 ml of an aqueous solution containing 2 wt% sodium hydroxide, 25 g of tetrapropylammonium bromide and 2.7 g of aluminum sulfate were added. The mixture was stirred vigorously at room temperature until completely dissolved. Then, 157 g of 30% silica sol was added dropwise and stirred at room temperature for 2 h. Next, 8.8 g of 3-aminopropyltriethoxysilane was added dropwise and stirred in a water bath at 30 °C for 2 h. The mixture was then allowed to stand overnight at room temperature for aging. Subsequently, the solution was transferred to a crystallization vessel and heated to 160 °C at a rate of 2 °C / min, maintained for 48 h, and then cooled to room temperature at a rate of 0.5 °C / min. The mixture was removed, filtered to obtain a solid, and then washed with deionized water until the filtrate was neutral. The solid was dried in a vacuum drying oven (80 °C, 0.1 kPa) for 10 h and then calcined in a muffle furnace at 550 °C for 5 h to obtain a hierarchical porous molecular sieve support.
[0050] (2) Catalyst preparation
[0051] The prepared hierarchical porous molecular sieve support was ultrasonically impregnated with a linker and active component solution in a certain proportion. For every 8 hours of impregnation, ultrasonic assistance was performed for 30 minutes, for a total of 24 hours. After impregnation, the solid was vacuum dried at 110℃ for 2 hours, and then calcined at 550℃ in air atmosphere in a muffle furnace for 4 hours to obtain the catalyst.
[0052] The active component is one or more of potassium methoxide, potassium ethoxide, and potassium tert-butoxide, and the amount of the active component added is 2.0% of the carrier mass.
[0053] The binder is one or more of polyethylene glycol, polypropylene glycol, and cyclodextrin, and the amount added is determined according to the molar ratio of binder to active component of 5:1.
[0054] The second step is the preparation process of fuel additives:
[0055] Dimethyl carbonate and butanol were mixed and then reacted under the following conditions: temperature range: 80℃, molar ratio of dimethyl carbonate to butanol: 1:2, reaction time: 6h. After the reaction was completed, the resulting reaction mixture was distilled, and the fraction mixture above 140℃ was collected as a fuel additive.
[0056] Example 4:
[0057] Step 1: The catalyst preparation method is as follows:
[0058] (1) Carrier preparation
[0059] In 250 ml of an aqueous solution containing 2 wt% sodium hydroxide, 25 g of tetrapropylammonium bromide and 2.7 g of aluminum sulfate were added. The mixture was stirred vigorously at room temperature until completely dissolved. Then, 157 g of 30% silica sol was added dropwise and stirred at room temperature for 2 h. Next, 8.8 g of 3-aminopropyltriethoxysilane was added dropwise and stirred in a water bath at 30 °C for 2 h. The mixture was then allowed to stand overnight at room temperature for aging. Subsequently, the solution was transferred to a crystallization vessel and heated to 160 °C at a rate of 2 °C / min, maintained for 48 h, and then cooled to room temperature at a rate of 0.5 °C / min. The mixture was removed, filtered to obtain a solid, and then washed with deionized water until the filtrate was neutral. The solid was dried in a vacuum drying oven (80 °C, 0.1 kPa) for 10 h and then calcined in a muffle furnace at 550 °C for 5 h to obtain a hierarchical porous molecular sieve support.
[0060] (2) Catalyst preparation
[0061] The prepared hierarchical porous molecular sieve support was ultrasonically impregnated with a linker and active component solution in a certain proportion. For every 8 hours of impregnation, ultrasonic assistance was performed for 30 minutes, for a total of 24 hours. After impregnation, the solid was vacuum dried at 110℃ for 2 hours, and then calcined at 550℃ in air atmosphere in a muffle furnace for 4 hours to obtain the catalyst.
[0062] The active component is one or more of potassium methoxide, potassium ethoxide, and potassium tert-butoxide, and the amount of the active component added is 3% of the carrier mass.
[0063] The binder is one or more of polyethylene glycol, polypropylene glycol, and cyclodextrin, and the amount added is determined according to the molar ratio of binder to active component of 4:1.
[0064] The second step is the preparation process of fuel additives:
[0065] Dimethyl carbonate and butanol were mixed and then reacted under the following conditions: temperature range: 90℃, molar ratio of dimethyl carbonate to butanol: 1:3, reaction time: 6h. After the reaction was completed, the resulting reaction mixture was distilled, and the fraction mixture above 140℃ was collected as a fuel additive.
[0066] Comparative Example 1:
[0067] Step 1: The catalyst preparation method is as follows:
[0068] (1) Carrier preparation
[0069] In 250 ml of an aqueous solution containing 2 wt% sodium hydroxide, 25 g of tetrapropylammonium bromide and 2.7 g of aluminum sulfate were added. The mixture was stirred vigorously at room temperature until completely dissolved. Then, 157 g of 30% silica sol was added dropwise and stirred at room temperature for 2 h. Next, 8.8 g of 3-aminopropyltriethoxysilane was added dropwise and stirred in a water bath at 30 °C for 2 h. The mixture was then allowed to stand overnight at room temperature for aging. Subsequently, the solution was transferred to a crystallization vessel and heated to 160 °C at a rate of 2 °C / min, maintained for 48 h, and then cooled to room temperature at a rate of 0.5 °C / min. The mixture was removed, filtered to obtain a solid, and then washed with deionized water until the filtrate was neutral. The solid was dried in a vacuum drying oven (80 °C, 0.1 kPa) for 10 h and then calcined in a muffle furnace at 550 °C for 5 h to obtain a hierarchical porous molecular sieve support.
[0070] (2) Catalyst preparation
[0071] The prepared hierarchical porous molecular sieve support was ultrasonically impregnated with a linker and active component solution in a certain proportion. For every 8 hours of impregnation, ultrasonic assistance was performed for 30 minutes, for a total of 24 hours. After impregnation, the solid was vacuum dried at 110℃ for 2 hours, and then calcined at 550℃ in air atmosphere in a muffle furnace for 4 hours to obtain the catalyst.
[0072] The active component is sodium methoxide, and the amount of the active component added is 0.5% of the carrier mass.
[0073] The binder is one or more of polyethylene glycol, polypropylene glycol, and cyclodextrin, and the amount added is determined according to the molar ratio of binder to active component of 1:5.
[0074] The second step is the preparation process of fuel additives:
[0075] Dimethyl carbonate and butanol were mixed and then reacted under the following conditions: temperature range: 80℃, molar ratio of dimethyl carbonate to butanol: 1:2, reaction time: 8h. After the reaction was completed, the resulting reaction mixture was distilled, and the fraction mixture above 140℃ was collected as a fuel additive.
[0076] Comparative Example 2:
[0077] Step 1: The catalyst preparation method is as follows:
[0078] (1) Carrier preparation
[0079] In 250 ml of an aqueous solution containing 2 wt% sodium hydroxide, 25 g of tetrapropylammonium bromide and 2.7 g of aluminum sulfate were added. The mixture was stirred vigorously at room temperature until completely dissolved. Then, 157 g of 30% silica sol was added dropwise and stirred at room temperature for 2 h. Next, 8.8 g of 3-aminopropyltriethoxysilane was added dropwise and stirred in a water bath at 30 °C for 2 h. The mixture was then allowed to stand overnight at room temperature for aging. Subsequently, the solution was transferred to a crystallization vessel and heated to 160 °C at a rate of 2 °C / min, maintained for 48 h, and then cooled to room temperature at a rate of 0.5 °C / min. The mixture was removed, filtered to obtain a solid, and then washed with deionized water until the filtrate was neutral. The solid was dried in a vacuum drying oven (80 °C, 0.1 kPa) for 10 h and then calcined in a muffle furnace at 550 °C for 5 h to obtain a hierarchical porous molecular sieve support.
[0080] (2) Catalyst preparation
[0081] The prepared hierarchical porous molecular sieve support was ultrasonically impregnated with a linker and active component solution in a certain proportion. For every 8 hours of impregnation, ultrasonic assistance was performed for 30 minutes, for a total of 24 hours. After impregnation, the solid was vacuum dried at 110℃ for 2 hours, and then calcined at 550℃ in air atmosphere in a muffle furnace for 4 hours to obtain the catalyst.
[0082] The active component is potassium ethoxide, and the amount of the active component added is 0.8% of the carrier mass.
[0083] The binder is propylene glycol, and the amount added is determined according to the molar ratio of binder to active component of 3:1;
[0084] The second step is the preparation process of fuel additives:
[0085] Dimethyl carbonate and butanol were mixed and then reacted under the following conditions: temperature range: 80℃, molar ratio of dimethyl carbonate to butanol: 1:3, reaction time: 8 hours. After the reaction was completed, the resulting reaction mixture was distilled, and the fraction collected above 140℃ was used as a fuel additive.
[0086] Comparative Example 3:
[0087] Step 1: The catalyst preparation method is as follows:
[0088] (1) Carrier preparation
[0089] In 250 ml of an aqueous solution containing 2 wt% sodium hydroxide, 25 g of tetrapropylammonium bromide and 2.7 g of aluminum sulfate were added. The mixture was stirred vigorously at room temperature until completely dissolved. Then, 157 g of 30% silica sol was added dropwise and stirred at room temperature for 2 h. Next, 8.8 g of 3-aminopropyltriethoxysilane was added dropwise and stirred in a water bath at 30 °C for 2 h. The mixture was then allowed to stand overnight at room temperature for aging. Subsequently, the solution was transferred to a crystallization vessel and heated to 160 °C at a rate of 2 °C / min, maintained for 48 h, and then cooled to room temperature at a rate of 0.5 °C / min. The mixture was removed, filtered to obtain a solid, and then washed with deionized water until the filtrate was neutral. The solid was dried in a vacuum drying oven (80 °C, 0.1 kPa) for 10 h and then calcined in a muffle furnace at 550 °C for 5 h to obtain a hierarchical porous molecular sieve support.
[0090] (2) Catalyst preparation
[0091] The prepared hierarchical porous molecular sieve support was ultrasonically impregnated with a linker and active component solution in a certain proportion. For every 8 hours of impregnation, ultrasonic assistance was performed for 30 minutes, for a total of 24 hours. After impregnation, the solid was vacuum dried at 110℃ for 2 hours, and then calcined at 550℃ in air atmosphere in a muffle furnace for 4 hours to obtain the catalyst.
[0092] The active component is potassium hydroxide, and the amount of the active component added is 0.5% of the carrier mass.
[0093] The binder is polypropylene glycol, and the amount added is determined according to the molar ratio of binder to active component of 3:1;
[0094] The second step is the preparation process of fuel additives:
[0095] Dimethyl carbonate and butanol were mixed and then reacted under the following conditions: temperature range: 80℃, molar ratio of dimethyl carbonate to butanol: 1:3, reaction time: 8h. After the reaction was completed, the resulting reaction mixture was distilled, and the fraction mixture above 140℃ was collected as a fuel additive.
[0096] Comparative Example 4:
[0097] Commercially available ZSM-5 molecules and potassium ethoxide were directly mixed as a catalyst, with the potassium ethoxide added at 0.2% (mass ratio) of the support. Dimethyl carbonate and butanol were then mixed and reacted under the following conditions: temperature range: 80°C, dimethyl carbonate / butanol ratio: 1:3, reaction time: 8 h. After the reaction was complete, the resulting reaction mixture was distilled, and the fraction collected above 140°C was used as a fuel additive.
[0098] Catalyst performance evaluation methods:
[0099] The catalyst performance was evaluated in a high-pressure reactor. Dimethyl carbonate and butanol were added to the reactor in a specific ratio, and the catalyst was added at 1% of the raw material mass. The reactor was then sealed, and the temperature and time were set. The composition of the mixture after the reaction was analyzed by gas chromatography, and the conversion rate was calculated based on the mass of the fraction mixture above 140℃. The liquid mixture was separated after the reaction, and dimethyl carbonate and butanol were added again for repeated catalyst performance evaluation. The reaction and evaluation were carried out using the same method. The experimental results are shown in Table 1.
[0100] Table 1. Comparison of catalyst performance between application examples and comparative examples.
[0101] catalyst Conversion rate (%) Repeat use conversion rate (%) Example 1 73 70 Example 2 72 70 Example 3 74 72 Example 4 76 70 Comparative Example 1: 65 59 Comparative Example 2: 62 47 Comparative Example 3: 63 60 Comparative Example 4 55 43
[0102] A linker is added during the catalyst preparation process of this invention. This linker, utilizing molecular linkages with multiple active groups, offers advantages such as increased stability and loading of the potassium alkoxide active component. The catalyst performance was evaluated using a batch reactor by examining its stability in the transesterification reaction. Performance evaluation showed that the catalyst prepared using the linker had a higher product yield and feed conversion rate, exhibiting superior product yield. This is significant for improving the combustion performance of oxygenated fuels and reducing fuel costs.
Claims
1. A method for preparing an alcohol-based oxygenated fuel additive, characterized in that, Using a specific catalyst for transesterification, and with dimethyl carbonate and butanol as raw materials, a reaction mixture mainly composed of methyl butyl carbonate and dibutyl carbonate is prepared through transesterification. After fractionation, the oxygenated fuel additive is obtained. The method includes the following steps: (I) Catalyst Preparation: (1) Preparation of the carrier In 250 ml of an aqueous solution containing 2 wt% sodium hydroxide, 25 g of tetrapropylammonium bromide and 2.7 g of aluminum sulfate were added. The mixture was stirred vigorously at room temperature until completely dissolved. Then, 157 g of silica sol (30% by mass) was added dropwise and stirred at room temperature for 2 h. Next, 8.8 g of 3-aminopropyltriethoxysilane was added dropwise and stirred in a water bath at 30 °C for 2 h. The mixture was then allowed to stand overnight at room temperature for aging. Subsequently, the solution was transferred to a crystallization vessel and heated to 160 °C at a rate of 2 °C / min, maintained for 48 h, and then cooled to room temperature at a rate of 0.5 °C / min. The mixture was then removed, filtered to obtain a solid, and washed with deionized water until the filtrate was neutral. The solid was dried in a vacuum drying oven (80 °C, 0.1 kPa) for 10 h and then calcined in a muffle furnace at 550 °C for 5 h to obtain a hierarchical porous molecular sieve support. (2) Preparation of catalyst The prepared hierarchical porous molecular sieve support was subjected to equal-volume ultrasonic impregnation with active components and linker solutions. Ultrasonic assistance was performed for 30 minutes every 8 hours of impregnation, for a total of 24 hours. After impregnation, the solid was placed in a vacuum drying oven and dried at 110℃ for 2 hours. Then, it was calcined in a muffle furnace at 550℃ for 4 hours in an air atmosphere to obtain the catalyst. The active component is one or more of potassium methoxide, potassium ethoxide, and potassium tert-butoxide, and the amount of the active component added is 0.1% to 5% of the carrier mass. The binder is one or more of polyethylene glycol, polypropylene glycol, and cyclodextrin, and the amount added is determined according to the molar ratio of binder to active component of 1:1 to 10:
1. (II) Transesterification reaction and post-processing: Dimethyl carbonate and butanol are mixed and then reacted under the following conditions: temperature 70℃~120℃, molar ratio of dimethyl carbonate to butanol 1:2~1:4, reaction time 2~10h, the resulting reaction mixture is distilled, and the fraction mixture above 140℃ is collected as a fuel additive.