A method and apparatus for methanol modification

Abstract

The application discloses a methanol modification method and device, and belongs to the technical field of methanol deep processing technology. The method comprises five steps of methanol pretreatment, composite modifier preparation, low-temperature catalytic modification, refining separation, product detection and storage. The composite modifier and the composite catalytic system are used to realize the deep modification of methanol under low temperature and normal pressure, and solve the problems of low methanol calorific value, strong corrosion, poor lubricity, insufficient stability and the like. The device adopts an integrated modular structure, comprises a pretreatment unit, a composite modifier preparation unit, a catalytic reaction unit, a refining unit, a product storage unit and an intelligent control system which are sequentially connected, realizes continuous production, and is provided with a waste heat recovery and resource recycling mechanism, and is low in energy consumption and production cost. The application has the advantages of simple process, convenient operation, comprehensive modification effect, stable product quality, adaptation to multiple scene applications, and the like, and can promote the large-scale popularization and application of methanol as a clean alternative fuel.

Description

Technical Field

[0001] This invention relates to the field of methanol deep processing technology, and in particular to a methanol modification method and apparatus. Background Technology

[0002] Methanol, as a clean and renewable energy source, has a wide range of raw material sources (it can be produced from coal, natural gas, biomass, etc.), high combustion efficiency, and low emissions, making it an important alternative to traditional fossil fuels. It has broad application prospects in automotive, industrial boilers, and residential combustion. However, methanol itself has several inherent drawbacks that limit its large-scale application: First, methanol's calorific value is about 46% that of gasoline, leading to insufficient power and high fuel consumption when used directly. Second, methanol is highly polar and has a low lubrication coefficient, easily corroding metal parts and causing swelling of rubber seals, shortening equipment lifespan. Third, methanol easily absorbs moisture from the air, leading to fuel stratification and poor stability, especially causing cold start difficulties at low temperatures and vapor lock at high temperatures. Fourth, existing methanol modification technologies often suffer from complex processes, high-cost modifiers, limited modification effects, or demanding reaction conditions (high temperature and pressure), high energy consumption, and numerous byproducts, making it difficult to balance practicality and economy.

[0003] Currently, existing methanol modification technologies mainly fall into two categories: one involves physical mixing modification by adding single or composite modifiers. While the process is simple, the modifier formulation is often unreasonable, making it difficult to simultaneously address multiple issues such as corrosion, swelling, and insufficient calorific value. Furthermore, the modifiers are prone to stratification with methanol, resulting in poor stability. The other category employs chemical modification via catalytic reactions, such as methanol dehydration to dimethyl ether and methanol alkylation with olefins. Although this can improve the calorific value and stability of methanol, it requires high-temperature and high-pressure conditions, leading to large equipment investments, high energy consumption, and numerous reaction byproducts that can cause secondary pollution, resulting in low yields. For example, the current technology using ZSM-5 catalyst for methanol-to-gasoline reactions requires conditions of 250–350°C and 3.0–5.0 MPa, resulting in high construction and operating costs and significant safety hazards. On the other hand, modification methods that simply add corrosion inhibitors cannot solve the problems of insufficient calorific value and poor lubricity of methanol, making it difficult to meet the needs of high-end applications such as automotive.

[0004] Furthermore, existing modification devices are mostly single-function structures, unable to achieve integrated continuous operation of modifier preparation, methanol pretreatment, catalytic modification, and purification separation. They suffer from drawbacks such as cumbersome operation, low production efficiency, and large footprint, and lack precise parameter control mechanisms, resulting in significant fluctuations in the quality of modified products and difficulty in adapting to different application scenarios. Therefore, developing a methanol modification method and device that is simple in process, low in energy consumption, provides comprehensive modification effects, and enables integrated continuous production has become an urgent technical problem to be solved. Summary of the Invention

[0005] The purpose of this invention is to provide a methanol modification method and apparatus to achieve efficient methanol modification, solve problems such as low calorific value, strong corrosiveness, poor lubricity, and insufficient stability of methanol, simplify the process, reduce energy consumption, reduce by-products, improve the overall performance and production efficiency of modified methanol, and take into account practicality, economy and environmental protection.

[0006] To achieve the above objectives, the present invention provides a methanol modification method, comprising the following steps: S1. Methanol Pretreatment: Select industrial methanol with a purity ≥ 99.5% and send it to the pretreatment unit. Add 0.1%~0.3% of a dehydrating agent by weight of methanol. Stir for 15~20 minutes at 25~35℃ and a stirring speed of 300~400 r / min, and let stand for 10~15 minutes to remove moisture and trace impurities from the methanol to obtain refined methanol. The dehydrating agent can be recycled to reduce production costs. S2. Preparation of Composite Modifier: The composite modifier is prepared by selecting the following raw materials in parts by weight: 30-40 parts corrosion inhibitor, 20-30 parts calorific value enhancer, 10-15 parts lubrication enhancer, 5-10 parts stabilizer, and 20-30 parts low-carbon alcohol diluent; wherein, the corrosion inhibitor is prepared by mixing benzotriazole, mercaptobenzothiazole, methylbenzotriazole, organosilicon, and N,N-disalicylic acid-1,2-propylenediamine in a weight ratio of 2-4:1:1:1:1, and can form on the metal surface... It forms a dense protective film, effectively inhibiting corrosion; the calorific value enhancer is a mixture of tert-butanol, isooctanol, and coal tar naphtha in a weight ratio of 5:3:2, which can significantly increase the calorific value of methanol; the lubrication enhancer is a mixture of hydrogenated vegetable oil and polyetheramine in a weight ratio of 3:1, which improves the lubrication performance of methanol and avoids component wear; the stabilizer is 2,6-di-tert-butyl-p-cresol, which prevents methanol from oxidizing and deteriorating; the low-carbon alcohol diluent is a mixture of isopropanol and isobutanol in a weight ratio of 3:1, which improves the compatibility of each component and avoids stratification. S3. Low-temperature catalytic modification: The refined methanol obtained in step S1 is fed into the catalytic reaction unit. The composite modifier is added at a weight ratio of 100:8~12 of refined methanol to composite modifier. After stirring evenly, nitrogen gas is introduced as a protective gas (nitrogen flow rate is 0.5~1.0L / min). The temperature is raised to 80~100℃, the catalytic system is added, and the reaction is carried out at atmospheric pressure for 60~90min to obtain crude modified methanol. S4. Refining and Separation: The crude modified methanol obtained in step S3 is sent to the refining unit. First, solid impurities and catalyst residues are removed by precision filtration. Then, vacuum distillation is performed to remove light component impurities and excess low-carbon alcohols. The mid-distillation product is collected, which is the finished modified methanol. The light components produced by distillation can be recycled as a low-carbon alcohol diluent after condensation and recovery, thus realizing resource recycling and reducing production costs.

[0007] S5. Finished Product Testing and Storage: The modified methanol product is tested for indicators including calorific value, corrosiveness, lubricity, and stability. After passing the tests, it is sent to the finished product storage tank and stored in a sealed container at room temperature and pressure.

[0008] Preferably, in step S1, the dehydrating agent is a mixture of anhydrous calcium chloride and molecular sieve in a mass ratio of 2:1.

[0009] Preferably, in step S2, during preparation, the corrosion inhibitor is first added to 50% of the low-carbon alcohol diluent, stirred at 300 r / min for 10 min, and allowed to stand for 10 min to obtain mixture A; then the calorific value enhancer, lubricant enhancer, and stabilizer are added to the remaining 50% of the low-carbon alcohol diluent, stirred at 300 r / min for 10 min, and allowed to stand for 10 min to obtain mixture B; finally, mixture B is slowly added to mixture A, stirred at 300 r / min for 30 min, and allowed to stand for 30 min to obtain the composite modifier.

[0010] Preferably, in step S3, the reaction temperature is 85~95℃ and the reaction time is 70~80min, which can further reduce energy consumption while ensuring the modification effect; In step S3, the catalytic system is a composite catalyst, which is composed of catalyst one and catalyst two mixed in a weight ratio of 3:1. The amount of the catalytic system added is 0.5% to 1.0% of the mass of refined methanol. Catalyst one is composed of 83% aggregate, 7% aluminum chloride, 3% zinc chloride, and 7% phosphoric acid. Catalyst two is composed of 26% aggregate, 15% copper oxide, 28% iron powder, 0.6% cobalt powder, 10% sodium carbonate, 12.4% calcium oxide, and 8% nickel oxide. This catalytic system can realize the mild alkylation and etherification reaction of methanol at low temperature and normal pressure, improve the calorific value and stability, and avoid the energy consumption and safety problems caused by high temperature and high pressure.

[0011] Preferably, in step S4, the vacuum degree of the reduced pressure distillation is 0.08~0.09MPa, and the distillation temperature is 70~80℃, to ensure that light component impurities are fully separated and improve the purity of the finished product.

[0012] The present invention also provides an apparatus for methanol modification, which adopts an integrated modular structure, including a pretreatment unit, a composite modifier preparation unit, a catalytic reaction unit, a purification unit, a finished product storage unit, a waste heat recovery component, and an intelligent control system for controlling the operation of each unit, wherein each unit is connected by a sealed pipeline, and the pipeline is equipped with a flow regulating valve and a pressure gauge. The pretreatment unit includes a pretreatment tank, which has a double-layer insulation structure and a polytetrafluoroethylene corrosion-resistant coating on the inner wall. A first agitator is installed on the top of the pretreatment tank, and the agitator's paddle extends into the lower part of the tank. A dehydrating agent addition port and a feed port are respectively provided on both sides of the top of the pretreatment tank. A settling area is provided at the bottom of the pretreatment tank, and a discharge port is provided at the bottom of the settling area. A sludge discharge port is provided at the bottom of the pretreatment tank.

[0013] Preferably, the composite modifier preparation unit includes a preparation tank with a double-layer structure and an anti-stick coating on the inner wall; a dual-component feeding assembly is installed on the top of the preparation tank, which is divided into an A-component inlet and a B-component inlet; a second stirrer is installed on the top of the preparation tank, which adopts a dual-paddle structure; a first temperature control assembly is installed in the jacket of the preparation tank to control the preparation temperature at 25~35℃; and a discharge port is provided at the bottom of the preparation tank, which is connected to the catalytic reaction unit through a flow regulating valve.

[0014] Preferably, the catalytic reaction unit includes a reaction vessel, which is a corrosion-resistant high-pressure vessel, operating at atmospheric pressure, with a reserved high-pressure adapter interface, and a catalytic coating on the inner wall; a third stirrer is installed on the top of the reaction vessel, and the stirring speed of the third stirrer is adjustable to 300~400 r / min; a second temperature control component is installed in the jacket of the reaction vessel, using electric heating, with a temperature control accuracy of ±1℃, controlling the reaction temperature to 80~100℃; a nitrogen inlet component and a catalyst addition port are respectively provided on both sides of the top of the reaction vessel; a feed inlet is provided at the top of the reaction vessel, which is connected to the discharge ports of the pretreatment unit and the composite modifier preparation unit respectively; and a discharge port is provided at the bottom of the reaction vessel, which is connected to the purification unit.

[0015] Preferably, the refining unit includes a precision filter and a vacuum distillation column; the precision filter uses a ceramic filter element with a filtration accuracy of 0.22 μm, the inlet of the precision filter is connected to the outlet of the catalytic reaction unit, and the outlet of the precision filter is connected to the inlet of the vacuum distillation column; the vacuum distillation column adopts a packed column structure, with high-efficiency packing inside the column, and a condensation recovery component at the top, the outlet of which is connected to the inlet of the low-carbon alcohol diluent of the composite modifier preparation unit; the distillation column has an outlet in the middle, which is connected to the finished product storage unit; and the distillation column has a residue discharge port at the bottom. The finished product storage unit includes a finished product storage tank, a detection interface, and a discharge port; the finished product storage tank is a sealed structure with a corrosion-resistant coating on the inner wall; the detection interface is located at the top of the storage tank; the discharge port is located at the bottom of the storage tank; and the storage tank is equipped with a pressure safety valve and a breather valve.

[0016] Preferably, the intelligent control system includes a PLC controller, temperature sensors, pressure sensors, flow sensors, and a touch control panel; the temperature sensors are respectively installed in the pretreatment tank, preparation tank, reaction vessel, and distillation column; the pressure sensors are respectively installed on each pipeline and on the reaction vessel and storage tank; the pipelines of each unit are made of stainless steel and are equipped with sealing joints to prevent material leakage and improve the safety and sealing of the device; the flow sensors are installed on each feed and discharge pipeline; the PLC controller is electrically connected to the stirrer, temperature control component, flow regulating valve, nitrogen inlet component, precision filter, and vacuum distillation column; the touch control panel is used for parameter setting, operating status monitoring, and fault alarm, and can manually or automatically switch the operating mode; The waste heat recovery unit is installed in the jacket between the reactor and the vacuum distillation column to recover the waste heat generated during the reaction and distillation process, providing heating energy for the pretreatment unit and the composite modifier preparation unit.

[0017] Furthermore, the intelligent control system is also equipped with data recording and traceability functions, which can record parameters of the entire production process, facilitating quality control and process optimization.

[0018] Therefore, the present invention employs the above-mentioned methanol modification method and apparatus, and the technical effects are as follows: (1) This method is simple and easy to operate, with mild reaction conditions (mainly at room temperature and pressure, with only the catalytic step requiring a low temperature of 80~100℃). It does not require high temperature and high pressure equipment, has low energy consumption and low production cost, and can achieve large-scale continuous production. It is suitable for the preparation needs of modified methanol in various scenarios such as automotive, industrial and civilian use, such as the preparation of M70~M90 automotive modified methanol fuel and industrial boiler modified methanol fuel. It has been verified by bench tests at the National Automotive Inspection Center and meets the relevant standards and requirements.

[0019] (2) The prepared composite modifier is scientifically formulated and integrates functions such as corrosion inhibition, calorific value enhancement, lubrication enhancement, and stabilization and anti-stratification. It can solve multiple inherent defects of methanol at the same time. After modification, the calorific value of methanol is increased to 42~45MJ / kg (close to 90% of the calorific value of gasoline), the metal corrosion rate is reduced by more than 80%, the rubber swelling rate is ≤5%, the lubrication coefficient is increased by more than 30%, and the stability is significantly improved. It can be stored in a sealed container at room temperature and pressure for 6 months without stratification or deterioration, meeting the usage requirements of different scenarios.

[0020] (3) The device adopts an integrated modular structure, realizing continuous operation of pretreatment, modifier preparation, catalytic modification, purification separation and storage. The operation is simple, the production efficiency is high and the footprint is small. The intelligent control system can realize precise control of parameters to ensure stable product quality. It also has a waste heat recovery and resource recycling mechanism to further reduce production costs and improve economic efficiency. The device has strong adaptability and can flexibly adjust process parameters and modifier ratio according to different modification needs, making it highly practical.

[0021] (4) No toxic or harmful byproducts are generated in the entire process. The light components of the distillation can be recycled and the residue can be recycled as fuel. It meets the requirements of green, low-carbon and environmental protection, and is compatible with the national green and low-carbon transformation policy of the chemical industry. It can be quickly promoted and applied.

[0022] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0023] Figure 1 This is a flowchart of an embodiment of a methanol modification method according to the present invention; Figure 2 This is a schematic diagram of an embodiment of an apparatus for a methanol modification method according to the present invention. Detailed Implementation

[0024] The technical solution of the present invention will be further described below with reference to the accompanying drawings and embodiments.

[0025] Unless otherwise defined, the technical or scientific terms used in this invention shall have the ordinary meaning understood by one of ordinary skill in the art to which this invention pertains. The terms "first," "second," and similar terms used in this invention do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Terms such as "comprising" or "including" mean that the element or object preceding the word encompasses the elements or objects listed following the word and their equivalents, without excluding other elements or objects. Terms such as "connected" or "linked" are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. Terms such as "upper," "lower," "left," and "right" are used only to indicate relative positional relationships; when the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0026] Example 1 This embodiment is adapted for the preparation of high-grade modified methanol for automotive applications, such as... Figure 1 As shown, this invention provides a methanol modification method, comprising five steps: methanol pretreatment, preparation of a composite modifier, low-temperature catalytic modification, purification and separation, and finished product detection and storage. Detailed descriptions are as follows: S1, Methanol Pretreatment 1000 kg of industrial methanol conforming to GB 338-2021 superior grade and with a purity of 99.9% was selected and fed into a pretreatment tank. 0.2% of the methanol mass was added as a dehydrating agent, which was a mixture of anhydrous calcium chloride and molecular sieve at a mass ratio of 2:1. The ambient temperature was controlled at 30℃ and the stirring speed at 350 r / min, and the mixture was stirred continuously for 18 min. After that, it was allowed to stand for 12 min to remove impurities and separate into layers. Free water and trace mechanical impurities in the raw methanol were removed to obtain refined methanol with a moisture content of ≤0.04%. The dehydrating agent can be reused after filtration and recovery.

[0027] S2, Preparation of composite modifier The formula is as follows (by weight): 35 parts corrosion inhibitor, 25 parts calorific value enhancer, 12 parts lubricant enhancer, 8 parts stabilizer, and 25 parts low-carbon alcohol diluent.

[0028] Among them: corrosion inhibitors: benzotriazole, mercaptobenzothiazole, methylbenzotriazole, organosilicon, N,N-disalicylic acid-1,2-propanediamine = 3:1:1:1:1; Calorific value enhancer: tert-butanol, isooctyl alcohol, coal tar naphtha = 5:3:2; Lubricant enhancer: hydrogenated vegetable oil, polyetheramine = 3:1; The stabilizer used is 2,6-di-tert-butyl-p-cresol; Low-carbon alcohol diluent: isopropanol, isobutanol = 3:1.

[0029] Preparation process: First, add 35 parts of corrosion inhibitor to 12.5 parts of low-carbon alcohol diluent, stir at 300 r / min for 10 min, and let stand for 10 min to obtain mixture A; then add 25 parts of calorific value enhancer, 12 parts of lubrication enhancer, and 8 parts of stabilizer to the remaining 12.5 parts of low-carbon alcohol diluent, stir at the same speed for 10 min, and let stand for 10 min to obtain mixture B; slowly and uniformly inject mixture B into mixture A, stir at 300 r / min for 30 min, and let stand for 30 min to fully mix, thus obtaining a homogeneous and stable composite modifier.

[0030] S3, Low-temperature catalytic modification 1000 kg of refined methanol was introduced into the reactor, and the process for refining methanol was as follows: The composite modifier is added at a weight ratio of 100:10 and stirred thoroughly. High-purity nitrogen is introduced at a flow rate of 0.8 L / min as an inert protective gas to isolate it from air and prevent oxidation. The temperature is gradually increased to 90℃ under normal pressure, and then 0.75% of the mass of refined methanol is added to the composite catalytic system. The catalytic system was prepared by mixing catalyst one and catalyst two in a 3:1 mass ratio. Catalyst one consisted of 83% aggregate, 7% aluminum chloride, 3% zinc chloride, and 7% phosphoric acid. Catalyst two consisted of 26% aggregate, 15% copper oxide, 28% iron powder, 0.6% cobalt powder, 10% sodium carbonate, 12.4% calcium oxide, and 8% nickel oxide. The reaction was carried out at a constant temperature and atmospheric pressure for 75 minutes to complete the mild alkylation and etherification modification of methanol, resulting in crude modified methanol.

[0031] S4, Refining Separation The crude modified methanol was sequentially fed into a precision filter, where a 0.22μm ceramic filter element was used to thoroughly remove solid catalyst residue and insoluble impurities. The filtrate was then passed into a vacuum distillation column, with the system vacuum level controlled at 0.085MPa and the distillation temperature at 75℃, to separate and remove light impurities and excess low-carbon alcohol components. The middle section of the distillation column was collected as the finished product, and the light components recovered by condensation at the top of the column were directly refluxed to the composite modifier preparation unit for recycling as a low-carbon alcohol diluent. The small amount of residue at the bottom of the column was collected and used as auxiliary fuel.

[0032] S5. Finished Product Inspection and Storage The modified methanol product undergoes comprehensive testing for calorific value, metal corrosivity, rubber swelling rate, lubricity, and stratification stability. Once the tests are passed, it is transferred to a sealed finished product storage tank and stored in a closed container at room temperature and pressure.

[0033] The finished product performance indicators are as follows: calorific value 43.5 MJ / kg, metal corrosion rate 0.002 mm / a, rubber seal swelling rate 3.2%, lubrication coefficient 0.18, and no stratification, turbidity, or deterioration after 6 months of sealed storage at room temperature, fully meeting the standards for modified methanol fuel used in China VI vehicles.

[0034] The present invention also provides an apparatus for a methanol modification method, such as... Figure 2 As shown, the device adopts an integrated modular series arrangement, including a pretreatment unit, a composite modifier preparation unit, a catalytic reaction unit, a refining unit, a finished product storage unit, and an intelligent control system for controlling the operation of each unit. The units are connected by pressure-resistant stainless steel sealed pipes, and the sealed pipes are equipped with flow regulating valves and high-precision pressure gauges along the entire length.

[0035] The details of each unit are as follows: Pretreatment unit: The double-layer insulated pretreatment tank relies on the polytetrafluoroethylene coating on the inner wall to resist methanol corrosion. The first agitator at the top mixes the materials evenly throughout the entire process, the lower settling zone achieves natural solid-liquid stratification, and the bottom drain outlet periodically discharges precipitated impurities, thus completing the raw material refining pretreatment.

[0036] Composite Modifier Preparation Unit: The double-layer anti-sticking preparation tank adds two groups of raw liquids, A and B, respectively through a dual-component dispensing assembly. The dual-stirring paddle structure achieves thorough mixing of materials without dead zones. The first temperature control component maintains a constant preparation temperature of 25~35℃ to ensure the stability of the composition of each component of the modifier.

[0037] Catalytic reaction unit: The corrosion-resistant multi-functional reactor operates under normal atmospheric pressure and has a reserved high-pressure interface to adapt to special modification conditions; the second temperature control component accurately controls the temperature by ±1℃ to meet the requirements of low-temperature catalytic reaction, and nitrogen is introduced into the component to create an inert reaction environment throughout the process to ensure the stable progress of the modification reaction.

[0038] Refining Unit: A ceramic filter element precision filter removes impurities before the process, and a packed vacuum distillation column is used to achieve precise separation of components. The top condensation and recovery unit completes the closed-loop circulation of materials, significantly reducing raw material loss.

[0039] Waste heat recovery component: Simultaneously recovers waste heat from reactor heating and distillation column heat dissipation, providing a heat source for front-end pretreatment and modifier preparation processes, reducing the overall energy consumption of the entire unit by about 16%.

[0040] Intelligent control system: Relying on PLC controller to link temperature, pressure and flow sensors throughout the process, the touch panel can switch between fully automatic and manual operation modes with one click, automatically record production process parameters, realize traceability of production process and precise control of product quality; finished product storage tank is equipped with pressure safety valve and breather valve to ensure storage safety.

[0041] Example 2 This embodiment is adapted for the preparation of modified methanol for general industrial boilers. The specific steps are as follows: S1, Methanol Pretreatment 1000 kg of 99.5% pure industrial methanol was selected, and 0.1% of a compound dehydrating agent by weight of methanol was added. The mixture was stirred at 300 r / min for 15 min at 25℃ and allowed to stand for 10 min to complete the dehydration and impurity removal, thus preparing refined methanol.

[0042] S2, Preparation of composite modifier The weight ratio is as follows: 30 parts corrosion inhibitor, 20 parts calorific value enhancer, 10 parts lubrication enhancer, 5 parts stabilizer, and 20 parts low-carbon alcohol diluent. The formulation of each component and the preparation and stirring process are completely consistent with those in Example 1.

[0043] S3, Low-temperature catalytic modification The ratio of refined methanol to composite modifier is 100:8. Nitrogen gas is introduced at a flow rate of 0.5 L / min. The temperature is raised to 80℃ and the reaction is carried out at atmospheric pressure. The amount of catalyst added is 0.5% of the mass of refined methanol. The reaction is carried out at a constant temperature for 60 min to obtain crude modified methanol.

[0044] S4, Refining Separation The vacuum level was controlled at 0.08 MPa and the distillation temperature at 70°C. The remaining filtration and component recovery processes were the same as in Example 1.

[0045] S5. Finished product inspection and storage (same as in Example 1) Finished product performance indicators: calorific value 42.0 MJ / kg, metal corrosion rate 0.003 mm / a, rubber swelling rate 4.8%, suitable for use in industrial boilers, with lower production costs, and suitable for large-scale industrial heating scenarios.

[0046] Example 3 This embodiment is adapted for the preparation of modified methanol specifically for residential heating. The specific steps are as follows: S1, Methanol Pretreatment 1000 kg of 99.9% high-purity methanol was selected, and 0.3% of the methanol mass as a dehydrating agent was added. The mixture was stirred at 35℃ and 400 r / min for 20 min, and then allowed to stand for 15 min for deep dehydration and impurity removal.

[0047] S2, Preparation of composite modifier The formula consists of the following components by weight: 40 parts corrosion inhibitor, 30 parts calorific value enhancer, 15 parts lubricant enhancer, 10 parts stabilizer, and 30 parts low-carbon alcohol diluent. The preparation process remains unchanged.

[0048] S3, Low-temperature catalytic modification The ratio of refined methanol to composite modifier is 100:12. The nitrogen flow rate is 1.0 L / min. The temperature is raised to 100℃ and the reaction is carried out at atmospheric pressure. The amount of catalyst added is 1.0%. The modification is completed after 90 min of constant temperature reaction.

[0049] S4, Refining Separation Purification was completed under a vacuum of 0.09 MPa and a distillation temperature of 80℃.

[0050] S5. Finished product inspection and storage (same as in Example 1) Product performance indicators: calorific value 45.0 MJ / kg, metal corrosion rate 0.001 mm / a, rubber swelling rate 2.5%, excellent low-temperature anti-delamination and anti-gas lock performance, suitable for use in civil heating equipment in low-temperature areas of northern China.

[0051] Comparative Example 1 Traditional single physical modification: Commercially available conventional methanol corrosion inhibitors are directly mixed with industrial methanol at room temperature. There is no methanol pretreatment and dehydration process, no calorific value enhancement components, no lubricating modification components, no low-temperature catalytic reaction, and no vacuum distillation purification. Modified methanol is obtained solely through physical stirring and mixing. The basic purity of the remaining raw materials is consistent with that of the embodiments of this invention.

[0052] Table 1. Performance Comparison Data of Examples and Comparative Examples

[0053] The table above systematically compares the three sets of embodiments of the present invention with traditional modification processes from multiple dimensions, including fuel physicochemical properties, reaction process conditions, production economy, and practical applicability. It intuitively demonstrates the comprehensive advantages of the present invention compared with existing methanol modification technologies, and at the same time proves that the process, formula, and complete set of equipment of the present invention have solid practical applicability and technological advancement.

[0054] Compared to existing single physical modification methods, this invention, through the synergistic cooperation of raw material pretreatment, a dedicated five-element composite modifier, low-temperature and atmospheric-pressure composite catalysis, closed-loop refining and recycling, and an integrated complete set of equipment, significantly simplifies the production process, reduces equipment investment and operating energy consumption while maintaining or even improving fuel performance. Simultaneously, it thoroughly solves common industry problems such as methanol fuel corrosion, swelling, poor lubrication, and easy stratification. It balances product performance, production economy, safety, and environmental friendliness, possessing strong industrialization potential. This fully demonstrates that the technical solution of this invention is fully practical, novel compared to existing technologies, and creative in overcoming industry technical biases.

[0055] The reaction mechanism of this invention is as follows: 1. Methanol pretreatment dehydration mechanism In industrial methanol, free water molecules are highly polar and readily form hydrogen bonds with methanol, which is a key factor in fuel stratification, low-temperature precipitation, and accelerated metal electrochemical corrosion. This invention employs a dehydration system composed of anhydrous calcium chloride and molecular sieves. Anhydrous calcium chloride forms a crystalline hydrate with free water, thus achieving chemical water locking. Molecular sieves rely on their porous sieve structure to physically adsorb trace amounts of gaseous moisture and polar impurities; the two work together to disrupt the methanol-water hydrogen bond association structure, strictly controlling the moisture content of the raw methanol at an extremely low level, thus inhibiting the basic conditions for water absorption stratification and electrochemical corrosion from the source.

[0056] 2. Synergistic mechanism of composite modifiers The five-element compound modifier of this invention has a multi-dimensional synergistic mechanism of interfacial film formation, polarity neutralization, calorific value compensation, and antioxidant compatibility. Corrosion inhibition mechanism: Nitrogen heterocyclic compounds such as benzotriazole and methylbenzotriazole can form a dense monomolecular adsorption protective film on the surface of steel and aluminum alloys, blocking the contact between the polar methanol molecules and the metal substrate; organosilicon components fill the pores of the film layer, inhibiting the pitting and crevice corrosion of methanol on cast iron and oil circuit metals; long-chain amines neutralize the weak acidity of methanol and reduce the electrochemical corrosion potential difference.

[0057] In the rubber anti-swelling mechanism modifier, non-polar hydrocarbon components preferentially occupy the gaps between rubber polymer chains, weakening the swelling effect of polar methanol molecules penetrating in, constraining the relaxation and deformation of molecular chains in nitrile rubber and fluororubber seals, and controlling the swelling rate within an extremely low range.

[0058] The mechanism for improving calorific value is that tert-butanol, isooctanol, and coal tar naphtha are all high-carbon, high-hydrogen, and high-calorific-value components. They are molecularly miscible with methanol, which makes up for the defects of methanol's low carbon-hydrogen ratio and insufficient heat release during combustion. At the same time, the carbon-hydrogen-oxygen ratio of the mixed fuel is optimized, the combustion power characteristics are improved, and the power output is increased.

[0059] The lubrication enhancement mechanism of the hydrogenated vegetable oil long-chain fatty acid ester + polyetheramine compound system can form a fluid lubricating oil film on the surface of the friction pair, fill the defect of methanol without a lubricating medium, and reduce the wear of moving parts of engine oil pump and fuel injector.

[0060] The stable compatibility mechanism of 2,6-di-tert-butyl-p-cresol is to capture methanol oxidation free radicals and inhibit the oxidation and deterioration of alcohols; the low-carbon alcohol diluent of isopropanol / isobutanol has poor polarity in the system, which eliminates the phase separation tendency after multi-component compounding and achieves long-term homogeneous and stable storage.

[0061] 3. Core reaction mechanism of low-temperature and atmospheric-pressure composite catalysis Existing technologies generally hold that methanol upgrading, etherification, and alkylation require temperatures above 250°C and high pressure to activate the reaction, which is an inherent technical bias in the industry. This invention employs a two-component composite catalytic system to achieve mild and directional modification at 80-100°C under normal pressure. The reaction mechanism is as follows: Catalyst 1 (acidic Lewis acid system) provides weakly acidic active sites, weakens the C-O bond energy within the methanol molecule, reduces the activation energy of the methanol molecule, and promotes mild intermolecular dehydration and etherification of some methanol molecules, generating a small amount of high-calorific-value intermediates such as dimethyl ether and low-carbon methyl ether. The etherification reaction can be initiated without high temperature.

[0062] Catalyst 2 (metal composite active catalytic system) utilizes multiple active metal sites, including Cu, Fe, Ni, and Co, to achieve a mild alkylation grafting reaction of low-carbon alkanes. This process introduces short-chain hydrocarbon groups onto the methanol molecular chain, increasing the overall molecular carbon chain length and calorific value. Simultaneously, it regulates reaction selectivity, suppresses side reactions that generate hydrocarbon heavy oil and olefin carbon deposits, and ensures the yield and purity of the modified products.

[0063] The nitrogen inert protection reaction mechanism involves introducing nitrogen into the reaction system to isolate it from air and oxygen. This prevents methanol from oxidizing at high temperatures to produce acidic and corrosive byproducts such as formic acid and formaldehyde. On the other hand, it maintains a stable partial pressure at atmospheric pressure in the reaction system, preventing methanol from being lost through vapor evaporation and improving the utilization rate of raw materials.

[0064] 4. Mechanism of separation and purification by reduced pressure distillation Utilizing the differences in saturated vapor pressure among the components in the modified mixture: The light components, including excess low-carbon alcohols and trace amounts of unreacted small-molecule alcohols, have low boiling points and are preferentially vaporized and condensed for recovery under low pressure and low temperature. The main product, modified methanol, has a medium boiling point, and the middle fraction is collected stably. High-boiling-point colloids and catalyst ash residue heavy components are retained at the bottom of the tower and discharged centrally; the boiling point of the material is reduced by negative pressure, and the entire process is separated at low temperature to avoid the failure and decomposition of modified components caused by high temperature, thus preserving the modification effect to the greatest extent.

[0065] 5. Energy-saving cycle mechanism throughout the entire process Waste heat from the electric heating of the reactor and phase change heat from the distillation column are recovered through a waste heat recovery component to preheat the methanol feedstock and the modifier preparation system, thus achieving cascade utilization of heat. Low-carbon alcohols recovered from the top of the column are directly reused in the preparation of modifiers, thus constructing a closed-loop material cycle and reducing overall production costs and energy consumption from both thermodynamic and material balance perspectives.

[0066] Therefore, the present invention adopts the above-mentioned methanol modification method and apparatus to solve the problems of low calorific value, strong corrosiveness, poor lubricity and insufficient stability of methanol. At the same time, it simplifies the process, reduces energy consumption, reduces by-products, improves the comprehensive performance and production efficiency of modified methanol, and takes into account practicality, economy and environmental protection.

[0067] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A method for modifying methanol, characterized in that, Includes the following steps: S1. Select industrial methanol and send it into the pretreatment unit. Add 0.1%~0.3% of dehydrating agent by mass of methanol. Stir for 15~20 min at 25~35℃ and stirring speed of 300~400 r / min. Let it stand for 10~15 min to remove water and trace impurities from the methanol and obtain refined methanol. S2. By weight, the following raw materials are selected to prepare the composite modifier: 30-40 parts corrosion inhibitor, 20-30 parts calorific value enhancer, 10-15 parts lubrication enhancer, 5-10 parts stabilizer, and 20-30 parts low-carbon alcohol diluent; wherein, the corrosion inhibitor is composed of benzotriazole, mercaptobenzothiazole, methylbenzotriazole, organosilicon, and N,N-disalicylic acid-1,2-propanediamine in a weight ratio of 2-4:1:1:1:1; the calorific value enhancer is composed of tert-butanol, isooctanol, and coal tar naphtha in a weight ratio of 5:3:2; the lubrication enhancer is a mixture of hydrogenated vegetable oil and polyetheramine in a weight ratio of 3:1; the stabilizer is 2,6-di-tert-butyl-p-cresol; and the low-carbon alcohol diluent is composed of isopropanol and isobutanol in a weight ratio of 3:

1. S3. The refined methanol obtained in step S1 is fed into the catalytic reaction unit. The composite modifier is added at a weight ratio of 100:8~12 of refined methanol to composite modifier. After stirring evenly, nitrogen gas is introduced as a protective gas, the temperature is raised to 80~100℃, the catalytic system is added, and the reaction is carried out at atmospheric pressure for 60~90 min to obtain crude modified methanol. S4. The crude modified methanol obtained in step S3 is sent to the refining unit. First, solid impurities and catalyst residues are removed by precision filtration, and then vacuum distillation is performed to remove light component impurities and excess low-carbon alcohols. The mid-distillation product is collected, which is the finished modified methanol. S5. Conduct index testing on the finished modified methanol, including calorific value, corrosiveness, lubricity and stability. After passing the test, it is sent to the finished product storage tank and stored in a sealed container at room temperature and pressure.

2. The methanol modification method according to claim 1, characterized in that: In step S1, the dehydrating agent is a mixture of anhydrous calcium chloride and molecular sieve in a mass ratio of 2:

1.

3. The methanol modification method according to claim 1, characterized in that: In step S2, during preparation, the corrosion inhibitor is first added to 50% of the low-carbon alcohol diluent, stirred at 300 r / min for 10 min, and allowed to stand for 10 min to obtain mixture A; then the calorific value enhancer, lubricant enhancer, and stabilizer are added to the remaining 50% of the low-carbon alcohol diluent, stirred at 300 r / min for 10 min, and allowed to stand for 10 min to obtain mixture B; finally, mixture B is slowly added to mixture A, stirred at 300 r / min for 30 min, and allowed to stand for 30 min to obtain the composite modifier.

4. The methanol modification method according to claim 1, characterized in that: In step S3, the reaction temperature is 85~95℃ and the reaction time is 70~80min; In step S3, the catalytic system is a composite catalyst, which is composed of catalyst one and catalyst two mixed in a weight ratio of 3:

1. The amount of the catalytic system added is 0.5% to 1.0% of the mass of refined methanol. Catalyst one is composed of 83% aggregate, 7% aluminum chloride, 3% zinc chloride, and 7% phosphoric acid. Catalyst two is composed of 26% aggregate, 15% copper oxide, 28% iron powder, 0.6% cobalt powder, 10% sodium carbonate, 12.4% calcium oxide, and 8% nickel oxide.

5. The methanol modification method according to claim 1, characterized in that: In step S4, the vacuum degree of the reduced pressure distillation is 0.08~0.09MPa, and the distillation temperature is 70~80℃.

6. An apparatus for implementing the methanol modification method according to any one of claims 1 to 5, characterized in that, It adopts an integrated modular structure, including a pretreatment unit, a composite modifier preparation unit, a catalytic reaction unit, a refining unit, a finished product storage unit, a waste heat recovery component, and an intelligent control system for controlling the operation of each unit. The units are connected by sealed pipes, which are equipped with flow regulating valves and pressure gauges. The pretreatment unit includes a pretreatment tank, which has a double-layer insulation structure and a polytetrafluoroethylene corrosion-resistant coating on the inner wall. A first agitator is installed on the top of the pretreatment tank, and the agitator's paddle extends into the lower part of the tank. A dehydrating agent addition port and a feed port are respectively provided on both sides of the top of the pretreatment tank. A settling area is provided at the bottom of the pretreatment tank, and a discharge port is provided at the bottom of the settling area. A sludge discharge port is provided at the bottom of the pretreatment tank.

7. The apparatus for a methanol modification method according to claim 6, characterized in that: The composite modifier preparation unit includes a preparation tank with a double-layer structure and an anti-stick coating on the inner wall. A dual-component feeding assembly is installed on the top of the preparation tank, which has an inlet for component A and an inlet for component B. A second stirrer is installed on the top of the preparation tank, and the second stirrer adopts a dual-paddle structure. A first temperature control assembly is installed in the jacket of the preparation tank to control the preparation temperature at 25~35℃. An outlet is provided at the bottom of the preparation tank and is connected to the catalytic reaction unit through a flow regulating valve.

8. The apparatus for a methanol modification method according to claim 7, characterized in that: The catalytic reaction unit includes a reactor, which is a corrosion-resistant high-pressure reactor, operating at atmospheric pressure, with a reserved high-pressure adapter interface, and a catalytic coating on the inner wall; a third stirrer is installed on the top of the reactor, and the stirring speed of the third stirrer is adjustable to 300~400 r / min; a second temperature control component is installed in the reactor jacket, using electric heating, with a temperature control accuracy of ±1℃, controlling the reaction temperature to 80~100℃; a nitrogen inlet component and a catalyst addition port are respectively set on both sides of the top of the reactor; a feed inlet is set at the top of the reactor, which is connected to the outlet of the pretreatment unit and the composite modifier preparation unit respectively; and a discharge port is set at the bottom of the reactor, which is connected to the purification unit.

9. The apparatus for a methanol modification method according to claim 8, characterized in that: The refining unit includes a precision filter and a vacuum distillation column. The precision filter uses a ceramic filter element with a filtration accuracy of 0.22 μm. The inlet of the precision filter is connected to the outlet of the catalytic reaction unit, and the outlet of the precision filter is connected to the inlet of the vacuum distillation column. The vacuum distillation column adopts a packed column structure with high-efficiency packing inside. A condensation recovery component is provided at the top, and the outlet of the condensation recovery component is connected to the inlet of the low-carbon alcohol diluent of the composite modifier preparation unit. An outlet is provided in the middle of the distillation column, which is connected to the finished product storage unit. A residue discharge port is provided at the bottom of the distillation column. The finished product storage unit includes a finished product storage tank, a detection interface, and a discharge port; the finished product storage tank is a sealed structure with a corrosion-resistant coating on the inner wall; the detection interface is located at the top of the storage tank; the discharge port is located at the bottom of the storage tank; and the storage tank is equipped with a pressure safety valve and a breather valve.

10. The apparatus for a methanol modification method according to claim 9, characterized in that: The intelligent control system includes a PLC controller, temperature sensors, pressure sensors, flow sensors, and a touch operation panel; the temperature sensors are installed in the pretreatment tank, preparation tank, reaction vessel, and distillation column respectively; the pressure sensors are installed on each pipeline and on the reaction vessel and storage tank respectively; the pipelines of each unit are made of stainless steel and are equipped with sealed joints. Flow sensors are installed on each feed and discharge pipe; the PLC controller is electrically connected to the agitator, temperature control component, flow regulating valve, nitrogen inlet component, precision filter, and vacuum distillation column; the touch operation panel is used for parameter setting, operation status monitoring and fault alarm, and can switch the operation mode manually or automatically. The waste heat recovery unit is installed in the jacket between the reactor and the vacuum distillation column to recover the waste heat generated during the reaction and distillation process.

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