CN115975602B - Non-combustible mixed refrigerant suitable for low-temperature system - Google Patents
Non-combustible mixed refrigerant suitable for low-temperature system Download PDFInfo
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Abstract
The invention provides a nonflammable mixed refrigerant suitable for a low-temperature system, and belongs to the technical field of refrigerants. The composition comprises the following components: the first component comprises: difluoromethane, tetrafluoroethane; the second component: 2, 3-tetrafluoropropene; and a third component: n (N) 2 He; and a fourth component: 1,2, 3-heptafluoropropane 1,2,3, 4-nonafluorobutane 1,2, 3-pentafluoropropane; and a fifth component: monofluoroethane and dimethyl ether. The non-combustible mixed refrigerant composition suitable for the low-temperature system mainly adopts a non-combustible environment-friendly fluorine-containing compound component, has good heat transfer characteristic, low toxicity, safety, large evaporation latent heat, small density and good refrigeration effect, can effectively reduce cost through reasonable combination and proportion, is suitable for a low-temperature system of-50 to-130 ℃, and has wide application prospect.
Description
Technical Field
The invention relates to the technical field of refrigerants, in particular to a nonflammable mixed refrigerant suitable for a low-temperature system.
Background
The cryogenic multi-element mixed working medium throttling refrigerator utilizing the regenerative measure has the advantages of high efficiency, reliability, low manufacturing cost and the like, is widely applied to the fields of energy, chemical industry and low-temperature engineering, and is used for realizing deep cooling of devices, liquefaction of industrial gas and the like, such as the fields of low-temperature refrigerators, natural gas liquefaction and the like. Except for the refrigerating system flow and hardware facilities such as a compressor, a heat exchanger and the like, the most critical of the refrigerating technology is a multi-component mixed refrigerant. The multi-element mixed refrigerant applied to the mixed working medium throttling refrigeration system is generally composed of 3-7 components according to the requirements of a refrigeration temperature zone and the structural design of the system, and is characterized by typical non-azeotropic characteristics, and the heat equivalent matching between high-pressure refrigerant and low-pressure refrigerant is realized by utilizing the nonlinear characteristics that the enthalpy value of a phase change zone changes along with the temperature, so that the refrigeration efficiency is improved. From another angle, each component has higher isothermal throttling effect in a temperature range where the phase change occurs, and each component with different boiling point temperatures has higher refrigerating effect in the whole refrigerating temperature span range according to the matching relay of the boiling points. The principle of refrigerant screening and thermodynamic optimization can be found in the relevant academic literature, and will not be described in detail here.
Because the components are limited by basic physical parameters such as boiling point, solidifying point temperature and the like, and other physical and chemical properties such as flammability, toxicity and the like of the component working medium, the effective components of the mixed working medium, especially the optional components at low temperature, are very limited. Several patent or application to cryogenic mixed working medium composition and concentration proportion have been issued at present, wherein the temperature division areas of Chinese patent CN1079107C, CN1204222C, CN1189532C and CN1194063C propose series of multi-element mixed working medium for cryogenic throttling refrigeration technology, wherein the components consist of nitrogen, alkane and fluoride of partial alkane, and the mixture has no ozone destruction effect. Each component of the mixture is divided into a low-temperature component, a normal refrigeration temperature component, a medium-high-temperature component and a high-temperature component according to the boiling point difference, and each temperature component obtains a required multi-component mixed working medium according to a concentration ratio, so that the multi-component mixed working medium has higher thermodynamic efficiency. The alkane substances such as methane, ethane, propane and the like contained in the oil have good intersolubility with lubricating oil, small greenhouse effect and good environmental protection property, but certain combustibility of the system can be caused. And because of the existence of combustible components, the system needs to consider measures such as explosion prevention in the links of production, debugging, maintenance and the like, thereby increasing the production cost and the difficulty accepted by users, especially in the North America market.
Chinese patent CN100483040C (similar to what appears in US 6502410) proposes to use nitrogen (N) 2 ) Non-flammable multi-component mixed refrigerants consisting of Hydrogen Fluoride (HFCs) and perfluorinated compounds (FC) of argon (Ar) and alkanes, such as R23, R125, R134a, R236fa, R245fa and the like, wherein the lowest temperature can achieve 105K, and the non-flammable multi-component mixed refrigerants also comprise neon (Ne), helium (He) and the like. The patent also discloses that the components in the mixture are divided into different areas according to the boiling points of the components according to the different refrigeration temperature areas, and the components with different boiling points in each temperature area form an integral mixture according to a certain concentration proportion range. The whole mixture does not contain flammable alkane components and also does not contain components with ozone destruction of Hydrochlorofluorocarbons (HCFCs). But is less efficient than mixtures containing alkanes. Wherein, in order to avoid flammability, the selected nonflammable HFC substances such as HFC125, HFC236fa and other high boiling point components have higher green house effect potential (GWP).
Another US patent 5408848 proposes a mixed refrigerant refrigeration technology using CFC-free components to meet refrigeration demands above-150 ℃ minimum, wherein in the examples a mixed refrigerant composition based on R142b, R134a, R23, R14 and Ar is given. The composition of the mixture does not contain combustible components, but contains R142b which is HCFC substance, has ozone layer destruction effect, and belongs to the limitation and the forbidden.
When the mixed working medium throttling refrigeration technology is adopted to realize deep refrigeration, according to the principle of the deep refrigeration mixed working medium refrigeration technology, the boiling points of the components required by the adopted multiplex mixed working medium are gradually increased to the ambient temperature from the lowest temperature (which is lower than or at least equal to the lowest refrigeration temperature) according to the refrigeration temperature zone (see Cryogenics Volume 44,Issue 12,December 2004,Pages 847-857 for specific description). Thus low temperature refrigeration, for example-100 ℃, is achieved, the mixture must have components below-100 ℃, such as CF4 (R14), even Ar or N 2 Exists. Because of the limited number of low boiling point components existing in nature, the nonflammable substances in the natural working medium are generally composed of He, ne and N 2 Ar, etc., and only R14, etc., is included in the artificially synthesized substances. In addition, low-temperature refrigeration and removal of objects are realizedIn addition to the proper boiling point of the mass, it is also desirable that the freezing point temperature be low enough to avoid plugging the fluid channels, especially the throttled capillaries, by precipitation of solids at low temperatures. Therefore, he, ne, N in the components of the lowest temperature zone when low-temperature refrigeration is realized 2 Substances such as Ar and R14 are essentially necessary depending on the refrigeration temperature zone to be achieved, in particular N 2 Ar, R14, R23, etc. This can also be seen in patents CN100483040C and US5408848, both of which contain N 2 Ar, R14 and R23, but the mixture of the compositions also contains different compositions, for example, U.S. Pat. No. 4, 5408848 has R142b, and CN100483040C contains R125, R245fa, R236fa, etc.
It is known that for a mixture composed of a plurality of substances, the thermophysical properties are determined by the components of the mixture and the concentrations of the components, wherein the components are different or the components are identical but the concentrations are different, and the mixture can be completely different in terms of the difference in the thermophysical properties such as equivalent molecular weight, critical parameter, enthalpy entropy and the like. The components are the same, the concentration difference is more in common cold mixture refrigerants, for example, a non-azeotropic mixture composed of three substances of R32, R125 and R134a, the application occasions are different because the difference of the composition concentration can be divided into different refrigerants, and the mixture composed of the three substances and the commercialized serial numbers can be specifically divided into refrigerants of R407A-R407E and the like at present, and the refrigerants have completely different physical properties and substitution objects. These illustrative analyses are only illustrative of the problem that completely different mixtures can be formed from different concentrations containing part of the same component or even the same component, which can be determined in particular by the respective objective.
From the above analysis, it can be known that the prior art realizes that the method comprises the steps of N 2 The cryogenic multi-element nonflammable mixed refrigerant composed of Ar, R14, R23, other high boiling point substances and the like, but among the high boiling point components in the mixed refrigerant, substances containing Ozone Destruction Potential (ODP) such as R142b and the like or hydrofluorocarbon substances with high temperature chamber effect (GWP) such as R236fa and the like are adopted, and the environmental protection property is influenced. In addition, a plurality of HFC and FC substances and lubricationThe miscibility of oil is poor, the freezing point temperatures of HFC and FC substances with higher boiling points are higher, and the low-temperature oil solubility of the mixed refrigerant is poor, so that the nonflammable mixed refrigerant is generally applied to a multistage automatic cascade refrigeration system. In addition, a multistage vapor-liquid separation device is usually arranged in the system to separate lubricating oil and components with high freezing point temperature at a higher temperature so as to ensure the normal operation of the system.
Disclosure of Invention
The invention aims to provide a nonflammable mixed refrigerant suitable for a low-temperature system, which mainly adopts a nonflammable environment-friendly fluorine-containing compound component, has good heat transfer characteristic, low toxicity, safety, large evaporation latent heat, small density and good refrigerating effect, can effectively reduce cost through reasonable combination and proportion, is suitable for a low-temperature system of-50 to-130 ℃, and has wide application prospect.
The technical scheme of the invention is realized as follows:
the invention provides a nonflammable mixed refrigerant suitable for a low-temperature system, which consists of the following components:
the first component comprises: difluoromethane, tetrafluoroethane;
the second component: 2, 3-tetrafluoropropene;
and a third component: n (N) 2 、He；
And a fourth component: 1, 2-pentafluoropropane, 1,2, 3-heptafluoropropane 1, 3-hexafluoropropane, 1, 2-tetrafluoropropane 1, 3-hexafluoropropane 1, 2-tetrafluoropropane 1,2, 3-heptafluorobutane, 1,1,1,2,2,4,4,4-octafluorobutane 1,2, 3-pentafluoropropane, 1,2, 3-pentafluoropropane at least one of 1,2,3, 4-octafluorobutane and 1,1,1,2,2,3,3,4-octafluorobutane;
and a fifth component: monofluoroethane and dimethyl ether.
As a further improvement of the invention, the mass ratio of the first component to the second component to the third component to the fourth component to the fifth component is 25-30:15-20:2-5:10-15:3-5.
As a further improvement of the present invention, the fourth component comprises 1,2, 3-heptafluoropropane 1,2,3, 4-nonafluorobutane, 1,2, 3-pentafluoropropane, the mass ratio is 3-7:2-3:1-2.
As a further improvement of the invention, the mass ratio of difluoromethane to tetrafluoroethane in the first component is 5-10:3-5; n in the third component 2 The volume ratio of He is 7-12:5-7; the mass ratio of the monofluoroethane to the dimethyl ether in the fifth component is 4-7:2-3.
As a further improvement of the present invention, a stabilizer selected from at least one of alkyl aryl ether, thiol, lactone, thioether, nitromethane, alkylsilane, benzophenone derivative, diethylene terephthalic acid or diphenyl terephthalic acid is further included.
The invention further protects the use of a non-flammable mixed refrigerant as described above for a cryogenic system in a refrigeration system.
As a further improvement of the invention, lubricating oil is also included in the refrigeration system.
As a further improvement of the present invention, the lubricating oil is at least one selected from the group consisting of natural mineral oils, polyalkyl alcohol lubricating oils, polyol ester lubricating oils, alkylbenzene lubricating oils, polyalphaolefin lubricating oils and polyvinyl ethers.
As a further improvement of the invention, the lubricating oil comprises polyol ester lubricating oil and polyvinyl ether, and the mass ratio is 7-10:1-2; the preparation method of the polyol ester lubricating oil comprises the following steps:
s1, mixing raw material alcohol, raw material acid and a catalyst, heating for reaction, and heating for distillation to remove the acid to obtain crude ester;
s2, sequentially washing the crude ester prepared in the step S1 with alkali liquor and water, and drying to obtain polyol ester lubricating oil;
the raw material alcohol comprises isovaleryl tetraol, glycerol and trimethylolethane, and the mass ratio is 5-7:2-3:1;
the raw material acid comprises n-decanoic acid and isooctanoic acid, and the mass ratio is 7-10:2-5;
the temperature is raised to 100-110 ℃ for 3-5h.
Preferably, the preparation method of the polyol ester lubricating oil specifically comprises the following steps:
s1, mixing 7-10 parts by weight of raw material alcohol, 10-12 parts by weight of raw material acid and 0.01-0.1 part by weight of catalyst, heating to 100-110 ℃, reacting for 3-5 hours, heating, distilling to remove acid, and obtaining crude ester;
the raw material alcohol comprises isovaleryl tetraol, glycerol and trimethylolethane, and the mass ratio is 5-7:2-3:1;
the raw material acid comprises n-decanoic acid and isooctanoic acid, and the mass ratio is 7-10:2-5;
s2, sequentially using 2-5wt% NaOH or KOH solution and water to wash the crude ester prepared in the step S1, and drying to obtain the polyol ester lubricating oil.
As a further improvement of the present invention, the catalyst is prepared as follows:
preparation of Si-Ti-Zr oxide nanospheres: dissolving tetraethoxysilane and tetrabutyl titanate in an organic solvent, stirring and mixing uniformly, adding an aqueous solution containing zirconium chloride, an emulsifying agent and a pore-forming agent, emulsifying, dropwise adding ammonia water, stirring and reacting, centrifuging, washing and drying to obtain Si-Ti-Zr oxide nanospheres;
t2. preparation of magnetic Si-Ti-Zr oxide nanospheres: dissolving ferric chloride and ferrous chloride in water, adding the Si-Ti-Zr oxide nanospheres prepared in the step T1, dropwise adding ammonia water, stirring for reaction, separating by a magnet, washing and drying to obtain the magnetic Si-Ti-Zr oxide nanospheres;
T3.La 2 O 3 /MoO 3 is deposited by: and (3) dissolving lanthanum chloride and ammonium molybdate in water, adding the magnetic Si-Ti-Zr oxide nanospheres prepared in the step (T2), carrying out impregnation reaction, washing, drying and calcining to obtain the catalyst.
Preferably, the preparation method of the catalyst comprises the following steps:
preparation of Si-Ti-Zr oxide nanospheres: dissolving 5-10 parts by weight of tetraethoxysilane and 5-7 parts by weight of tetrabutyl titanate in 100 parts by weight of organic solvent, stirring and mixing for 10-15min, adding 50-70 parts by weight of aqueous solution containing 3-5 parts by weight of zirconium chloride, 0.5-1 part by weight of emulsifier and 0.2-0.4 part by weight of pore-forming agent, emulsifying for 10-15min with 12000-15000r/min, dropwise adding 10-15 parts by weight of 25-28wt% ammonia water, stirring and reacting for 3-5h, centrifuging, washing and drying to obtain Si-Ti-Zr oxide nanospheres;
the pore-forming agent is at least one selected from polyoxyethylene sorbitan fatty acid ester, polyethylene glycol octyl phenyl ether, cetyl trimethyl ammonium bromide, ethylene oxide-propylene oxide triblock copolymer PEO20-PPO70-PEO20 and PEO106-PPO70-PEO 106;
the organic solvent is at least one of petroleum ether, ethyl acetate, methyl acetate, butyl acetate and dichloromethane;
the emulsifier is at least one selected from Tween-20, tween-40, tween-60 and Tween-80;
t2. preparation of magnetic Si-Ti-Zr oxide nanospheres: dissolving 8 parts by weight of ferric chloride and 6-7 parts by weight of ferrous chloride in 50 parts by weight of water, adding 15-20 parts by weight of the Si-Ti-Zr oxide nanospheres prepared in the step T1, dropwise adding 10 parts by weight of 25-28wt% ammonia water, stirring and reacting for 1-2 hours, separating magnets, washing and drying to obtain the magnetic Si-Ti-Zr oxide nanospheres;
T3.La 2 O 3 /MoO 3 is deposited by: 3-5 parts by weight of lanthanum chloride and 4-7 parts by weight of ammonium molybdate are dissolved in 100 parts by weight of 50wt% ethanol water solution, 12-17 parts by weight of the magnetic Si-Ti-Zr oxide nanospheres prepared in the step T2 are added for soaking reaction for 1-2 hours, washing, drying and calcining at 300-500 ℃ for 2-4 hours, and thus the catalyst is prepared.
The invention has the following beneficial effects: difluoromethane (R32) has better heat transfer characteristic, in terms of heat transfer coefficient, R32 is more than 50% higher than R22 in the light pipe evaporation process, R32 is more than 30% higher than R22 in the reinforced pipe evaporation process, R32 is more than 40% higher than R22 in the light pipe condensation process, R32 is more than 30% higher than R22 in the reinforced pipe condensation process, in terms of pressure loss, both the light pipe and the reinforced pipe, R32 and R22 are very similar, meanwhile, the COP of R32 is more than about 5% higher than R22, and meanwhile, the refrigerant has incombustibility and environmental protection performance, and is a better refrigerant component.
2, 3-tetrafluoropropene (R1234 yf) has excellent environmental parameters, except odp=0 and a green house effect potential (GWP) <4, and its atmospheric decomposition products are the same as R134a, LCCP is lower than R134a, and is a clean and environment-friendly refrigerant component. Compared with R744, R1234ze has a harsher use condition, R1234yf has better application because of cis-trans isomer, meanwhile, R1234yf has refrigeration performance similar to that of R134a, and meanwhile, all indexes of R1234yf are better than those of R134a in terms of toxicity detection results in aspects of acute mortality, cardiac sensitivity, 13-week inhalation, development, outburst, denaturation, carcinogenicity, environmental influence and the like and 7 aspects. In addition, most of organic polymer substances can be well compatible, and the lubricating oil has good intersolubility with common lubricating oil, and can not react with metal materials (such as carbon steel, copper, brass, stainless steel and the like), so that the lubricating oil has wider application range.
Non-stoichiometric, cage-like crystalline compounds, i.e., refrigerant hydrates, formed from conventional refrigerants and water molecules under high pressure, low temperature conditions can crystallize and solidify above the freezing point while possessing the same or higher latent heat of vaporization as ice. However, most organic refrigerants are difficult to dissolve in water, so that the formation of the hydrate of the refrigerant has long induction period, slow growth speed and high supercooling degree. Synthesizing the refrigerant hydrate facilitates storage of the refrigerant. In the present invention, an auxiliary gas molecule (N 2 And He) can promote the synthesis of hydrate by R1234yf and the crystal structure formed is more stable because of N 2 And He has a molecular diameter smaller than the crystal cavity size and close to the crystal cavity size of the R1234yf hydrate, the synthesized R1234yf synthetic hydrate of which is also the most stable.
Tetrafluoroethane (HFC-134 a) is currently the best environmentally friendly alternative to difluoromethane CFC-12. HFC-134a does not contain chlorine atom, does not damage ozone layer, has good safety performance, and its refrigerating capacity and efficiency are very similar to CFC-12.
The fluoroethane (R161) has combustibility, the thermal property is similar to that of R22, in order to reduce the combustibility risk, the R161 and other refrigerants are mixed according to a certain proportion to form a mixed refrigerant, the evaporation latent heat is large, the density is small, the system filling amount can be reduced, the system filling amount is only about 78% of an R22 system, and the environmental protection performance is excellent. Dimethyl ether (DME) is a petroleum associated product, has low price, sufficient market supply and better thermodynamic property, and has the potential of green and environment-friendly refrigerant. However, DME thereof has flammability, and thus, it is also necessary to adjust the addition amount thereof in order to reduce the risk of flammable explosions.
The non-combustible mixed refrigerant composition suitable for the low-temperature system mainly adopts a non-combustible environment-friendly fluorine-containing compound component, has good heat transfer characteristic, low toxicity, safety, large evaporation latent heat, small density and good refrigeration effect, can effectively reduce cost through reasonable combination and proportion, is suitable for a low-temperature system of-50 to-130 ℃, and has wide application prospect.
The invention also includes the use of a non-flammable mixed refrigerant for a cryogenic system, to which lubricating oil is also added, in a refrigeration system. In a refrigeration system, in order to lubricate the surfaces of the parts that rub against each other, taking away the heat of friction, sealing the gap between the piston rings and the cylinder walls to ensure proper operation of the compressor, a certain amount of lubricating oil must be added. The freezing point of the lubricating oil is low, if the freezing point is high, the low-temperature fluidity is poor, the flow capacity is lost at low temperature of an evaporator and the like, deposition is formed, and the refrigeration efficiency and the refrigeration capacity are affected. In addition, when the temperature of the compressor is low, lubrication of parts is affected, abrasion is caused, and the service life of the compressor is affected. The polyol ester lubricating oil has good low-temperature performance, and the solidifying point of the polyol ester lubricating oil is lower than-130 ℃. Meanwhile, the polyol ester lubricating oil has proper viscosity, so that the phenomenon that the viscosity is too small, the normal oil film thickness is not easy to form on a friction surface to accelerate mechanical abrasion, or the viscosity is too large, the lubricating and sealing performances are good, but the power consumed by the refrigerating compressor per unit refrigerating capacity is increased, and the energy consumption is increased. Furthermore, the compound has good chemical stability and oxidation stability. The polyol ester lubricating oil can be used for more than 20 years in a fully-closed refrigeration compressor after being contacted with a refrigerant for a long time in a refrigeration system. At the same time, there is some solubility in the refrigerant of the present invention. In the invention, branched chain acid and straight chain acid are used as raw materials to adjust the molecular structure and distribution of the polyol ester, and the polyol ester lubricating oil has stronger polarity and good compatibility with the refrigerant.
The polyol ester is of a multi-element hindered structure, the branching degree is high, a serious steric effect exists in the esterification process, the ester with a low hydroxyl value is difficult to obtain, and a catalyst is required to be added and the reaction speed and the esterification degree are improved at high temperature. Among them, strongly acidic catalysts such as sulfuric acid, phosphoric acid, p-toluenesulfonic acid and the like are very effective esterification catalysts, but also have serious non-esterification catalysis and side reaction phenomena; weak acid catalysts such as titanates, metal oxides, etc. require higher reaction temperatures and have low catalytic efficiency.
The catalyst La prepared by the invention 2 O 3 /MoO 3 The magnetic Si-Ti-Zr oxide nanospheres have the advantages of good catalytic activity of esterification reaction, good selectivity, easy treatment and storage, easy repeated use, simple post-treatment, high thermal stability, high acid strength, no corrosion, convenient use and the like, and the specific surface area of the nanospheres is increased by adding the pore-forming agent in the process of preparing the magnetic nanospheres, the nanospheres are not easy to coke and deactivate in the reaction process, and the service life is prolonged. At the same time La 2 O 3 And MoO 3 The combination of the two obviously improves the catalytic activity and selectivity of the catalyst, greatly reduces side reactions of the esterification reaction, has few byproducts, high esterification degree and obviously improves the reaction speed.
Drawings
In order to more clearly illustrate the embodiments of the invention or the technical solutions of the prior art, the drawings which are used in the description of the embodiments or the prior art will be briefly described, it being obvious that the drawings in the description below are only some embodiments of the invention, and that other drawings can be obtained according to these drawings without inventive faculty for a person skilled in the art.
FIG. 1 is an SEM image of the catalyst prepared in preparation example 1 of the invention.
Detailed Description
The following description of the technical solutions in the embodiments of the present invention will be clear and complete, and it is obvious that the described embodiments are only some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
PREPARATION EXAMPLE 1 catalyst
The preparation method comprises the following steps:
preparation of Si-Ti-Zr oxide nanospheres: dissolving 5 parts by weight of tetraethoxysilane and 5 parts by weight of tetrabutyl titanate in 100 parts by weight of ethyl acetate, stirring and mixing for 10min, adding 50 parts by weight of aqueous solution containing 3 parts by weight of zirconium chloride, 0.5 part by weight of tween-20 and 0.2 part by weight of polyoxyethylene sorbitan fatty acid ester, emulsifying for 10min at 12000r/min, dropwise adding 10 parts by weight of 25wt% ammonia water, stirring and reacting for 3h, centrifuging for 15min at 5000r/min, washing with deionized water, and drying for 2h at 105 ℃ to obtain Si-Ti-Zr oxide nanospheres;
t2. preparation of magnetic Si-Ti-Zr oxide nanospheres: dissolving 8 parts by weight of ferric chloride and 6 parts by weight of ferrous chloride in 50 parts by weight of water, adding 15 parts by weight of the Si-Ti-Zr oxide nanospheres prepared in the step T1, dropwise adding 10 parts by weight of 25wt% ammonia water under the protection of nitrogen, stirring and reacting for 1h, separating by using a magnet, washing by using deionized water, and drying at 105 ℃ for 2h to obtain magnetic Si-Ti-Zr oxide nanospheres;
T3.La 2 O 3 /MoO 3 is deposited by: 3 parts by weight of lanthanum chloride and 4 parts by weight of ammonium molybdate are dissolved in 100 parts by weight of 50wt% ethanol aqueous solution, 12 parts by weight of the magnetic Si-Ti-Zr oxide nanospheres prepared in the step T2 are added, the impregnation reaction is carried out for 1h, the deionized water is used for washing, the drying is carried out at 105 ℃ for 2h, the calcination is carried out at 300 ℃ for 2h, the catalyst is prepared, and as can be seen from the SEM image of the prepared catalyst, the porous structure with the particle size of 200-500nm is prepared.
PREPARATION EXAMPLE 2 catalyst
The preparation method comprises the following steps:
preparation of Si-Ti-Zr oxide nanospheres: dissolving 10 parts by weight of tetraethoxysilane and 7 parts by weight of tetrabutyl titanate in 100 parts by weight of butyl acetate, stirring and mixing for 15min, adding 70 parts by weight of an aqueous solution containing 5 parts by weight of zirconium chloride, 1 part by weight of tween-60 and 0.4 part by weight of polyethylene glycol octyl phenyl ether, emulsifying for 15min at 15000r/min, dropwise adding 15 parts by weight of 28wt% ammonia water, stirring and reacting for 5h, centrifuging for 15min at 5000r/min, washing with deionized water, and drying for 2h at 105 ℃ to obtain Si-Ti-Zr oxide nanospheres;
t2. preparation of magnetic Si-Ti-Zr oxide nanospheres: dissolving 8 parts by weight of ferric chloride and 6-7 parts by weight of ferrous chloride in 50 parts by weight of water, adding 15-20 parts by weight of the Si-Ti-Zr oxide nanospheres prepared in the step T1, dropwise adding 10 parts by weight of 25-28wt% ammonia water under the protection of nitrogen, stirring and reacting for 1-2 hours, separating by using a magnet, washing by using deionized water, and drying at 105 ℃ for 2 hours to obtain magnetic Si-Ti-Zr oxide nanospheres;
T3.La 2 O 3 /MoO 3 is deposited by: 5 parts by weight of lanthanum chloride and 7 parts by weight of ammonium molybdate are dissolved in 100 parts by weight of 50wt% ethanol water solution, 17 parts by weight of the magnetic Si-Ti-Zr oxide nanospheres prepared in the step T2 are added for soaking reaction for 2 hours, deionized water is used for washing, drying is carried out at 105 ℃ for 2 hours, and calcination is carried out at 500 ℃ for 4 hours, so that the catalyst is prepared.
PREPARATION EXAMPLE 3 catalyst
The preparation method comprises the following steps:
preparation of Si-Ti-Zr oxide nanospheres: dissolving 7 parts by weight of tetraethoxysilane and 6 parts by weight of tetrabutyl titanate in 100 parts by weight of dichloromethane, stirring and mixing for 12min, adding 60 parts by weight of aqueous solution containing 4 parts by weight of zirconium chloride, 0.7 part by weight of tween-80 and 0.3 part by weight of cetyltrimethylammonium bromide, emulsifying for 12min at 13500r/min, dropwise adding 12 parts by weight of 26wt% ammonia water, stirring and reacting for 4h, centrifuging for 15min at 5000r/min, washing with deionized water, and drying for 2h at 105 ℃ to obtain Si-Ti-Zr oxide nanospheres;
t2. preparation of magnetic Si-Ti-Zr oxide nanospheres: dissolving 8 parts by weight of ferric chloride and 6.5 parts by weight of ferrous chloride in 50 parts by weight of water, adding 17 parts by weight of the Si-Ti-Zr oxide nanospheres prepared in the step T1, dropwise adding 10 parts by weight of 26wt% ammonia water under the protection of nitrogen, stirring and reacting for 1.5 hours, separating the magnet, washing with deionized water, and drying at 105 ℃ for 2 hours to obtain magnetic Si-Ti-Zr oxide nanospheres;
T3.La 2 O 3 /MoO 3 is deposited by: 4 parts by weight of lanthanum chloride and 5 parts by weight of ammonium molybdate are dissolved in 100 parts by weight of 50wt% ethanol water solution, 15 parts by weight of the magnetic Si-Ti-Zr oxide nanospheres prepared in the step T2 are added, the impregnation reaction is carried out for 1-2 hours, deionized water washing is carried out, drying is carried out at 105 ℃ for 2 hours, and calcination is carried out at 400 ℃ for 3 hours, thus obtaining the catalyst.
Comparative preparation example 1
In comparison with preparation example 3, the difference is that zirconium chloride is not added in step S1.
The method comprises the following steps:
preparation of Si-Ti oxide nanospheres: 7 parts by weight of tetraethoxysilane and 10 parts by weight of tetrabutyl titanate are dissolved in 100 parts by weight of dichloromethane, stirred and mixed for 12min, 60 parts by weight of aqueous solution containing 0.7 part by weight of tween-80 and 0.3 part by weight of cetyltrimethylammonium bromide is added, emulsification is carried out for 12min at 13500r/min, 12 parts by weight of 26wt% ammonia water is added dropwise, stirring reaction is carried out for 4h, centrifugation is carried out for 15min at 5000r/min, deionized water washing is carried out, and drying is carried out at 105 ℃ for 2h, thus obtaining the Si-Ti oxide nanospheres.
Comparative preparation example 2
In comparison with preparation example 3, the difference is that tetrabutyl titanate is not added in step S1.
The method comprises the following steps:
preparation of Si-Zr oxide nanospheres: dissolving 7 parts by weight of tetraethoxysilane in 100 parts by weight of dichloromethane, stirring and mixing for 12min, adding 60 parts by weight of an aqueous solution containing 10 parts by weight of zirconium chloride, 0.7 part by weight of tween-80 and 0.3 part by weight of cetyltrimethylammonium bromide, emulsifying for 12min at 13500r/min, dropwise adding 12 parts by weight of 26wt% ammonia water, stirring and reacting for 4h, centrifuging for 15min at 5000r/min, washing with deionized water, and drying at 105 ℃ for 2h to obtain the Si-Zr oxide nanospheres.
Comparative preparation example 3
In comparison with preparation example 3, the difference is that zirconium chloride and tetrabutyl titanate are not added in step S1.
The method comprises the following steps:
preparation of si oxide nanospheres: 17 parts by weight of ethyl orthosilicate is dissolved in 100 parts by weight of dichloromethane, stirred and mixed for 12min, 60 parts by weight of aqueous solution containing 0.7 part by weight of tween-80 and 0.3 part by weight of cetyltrimethylammonium bromide is added, 13500r/min is emulsified for 12min, 12 parts by weight of 26wt% ammonia water is added dropwise, stirring reaction is carried out for 4h,5000r/min is centrifuged for 15min, deionized water is used for washing, and drying is carried out for 2h at 105 ℃, so that Si oxide nanospheres are obtained.
Comparative preparation example 4
In comparison with preparation example 3, the difference is that step S2 is not performed.
The method comprises the following steps:
preparation of Si-Ti-Zr oxide nanospheres: dissolving 7 parts by weight of tetraethoxysilane and 6 parts by weight of tetrabutyl titanate in 100 parts by weight of dichloromethane, stirring and mixing for 12min, adding 60 parts by weight of aqueous solution containing 4 parts by weight of zirconium chloride, 0.7 part by weight of tween-80 and 0.3 part by weight of cetyltrimethylammonium bromide, emulsifying for 12min at 13500r/min, dropwise adding 12 parts by weight of 26wt% ammonia water, stirring and reacting for 4h, centrifuging for 15min at 5000r/min, washing with deionized water, and drying for 2h at 105 ℃ to obtain Si-Ti-Zr oxide nanospheres;
T2.La 2 O 3 /MoO 3 is deposited by: 4 parts by weight of lanthanum chloride and 5 parts by weight of ammonium molybdate are dissolved in 100 parts by weight of 50wt% ethanol water solution, 15 parts by weight of Si-Ti-Zr oxide nanospheres prepared in the step T1 are added, the soaking reaction is carried out for 1-2 hours, deionized water is used for washing, the drying is carried out at 105 ℃ for 2 hours, and the calcination is carried out at 400 ℃ for 3 hours, so that the catalyst is prepared.
Comparative preparation example 5
In comparison with preparation example 3, the difference is that lanthanum chloride is not added in step S3.
The method comprises the following steps:
T3.La 2 O 3 /MoO 3 is deposited by: and (2) dissolving 12 parts by weight of ammonium molybdate into 100 parts by weight of 50wt% ethanol water solution, adding 17 parts by weight of the magnetic Si-Ti-Zr oxide nanospheres prepared in the step (T2), carrying out an impregnation reaction for 2 hours, washing with deionized water, drying at 105 ℃ for 2 hours, and calcining at 500 ℃ for 4 hours to prepare the catalyst.
Comparative preparation example 6
The difference from preparation example 3 is that ammonium molybdate is not added in step S3.
The method comprises the following steps:
T3.La 2 O 3 /MoO 3 is deposited by: and (2) dissolving 12 parts by weight of lanthanum chloride in 100 parts by weight of 50wt% ethanol aqueous solution, adding 17 parts by weight of the magnetic Si-Ti-Zr oxide nanospheres prepared in the step (T2), carrying out an impregnation reaction for 2 hours, washing with deionized water, drying at 105 ℃ for 2 hours, and calcining at 500 ℃ for 4 hours to prepare the catalyst.
Comparative preparation example 7
In comparison with preparation example 3, the difference is that step S3 is not performed.
The method comprises the following steps:
preparation of Si-Ti-Zr oxide nanospheres: dissolving 7 parts by weight of tetraethoxysilane and 6 parts by weight of tetrabutyl titanate in 100 parts by weight of dichloromethane, stirring and mixing for 12min, adding 60 parts by weight of aqueous solution containing 4 parts by weight of zirconium chloride, 0.7 part by weight of tween-80 and 0.3 part by weight of cetyltrimethylammonium bromide, emulsifying for 12min at 13500r/min, dropwise adding 12 parts by weight of 26wt% ammonia water, stirring and reacting for 4h, centrifuging for 15min at 5000r/min, washing with deionized water, and drying for 2h at 105 ℃ to obtain Si-Ti-Zr oxide nanospheres;
t2. preparation of magnetic Si-Ti-Zr oxide nanospheres: 8 parts by weight of ferric chloride and 6.5 parts by weight of ferrous chloride are dissolved in 50 parts by weight of water, 17 parts by weight of Si-Ti-Zr oxide nanospheres prepared in the step T1 are added, 10 parts by weight of 26wt% ammonia water is dropwise added under the protection of nitrogen, stirring reaction is carried out for 1.5 hours, magnet separation, deionized water washing and drying at 105 ℃ are carried out for 2 hours, and the magnetic Si-Ti-Zr oxide nanospheres are obtained.
Test example 1 Activity and repeat Performance of the catalyst
The catalytic activities of the catalysts prepared in preparation examples 1 to 3 and comparative examples 1 to 7 were examined with the reaction of glacial acetic acid with n-butanol to synthesize n-butyl acetate as a target reaction, and the reaction formulas are shown below.
The experimental steps are as follows: 11.5. 11.5 mL n-butanol, 7.2. 7.2 mL glacial acetic acid and 5wt% of catalyst are uniformly mixed and then heated for reaction, so that the reaction is judged to be complete when no more water is generated in the reaction vessel. The crude product was distilled after washing stepwise, and the 124-126 ℃ fractions were collected and the esterification rate was calculated.
The esterification rate referred to in this work is the ratio of the actual yield to the theoretical yield of n-butyl acetate obtained after the esterification reaction of acetic acid and n-butanol.
After the reaction liquid is cooled to room temperature, a magnet is used for separating the catalyst (filtering separation is adopted in comparative preparation example 4), then the catalyst is naturally dried and then is subjected to catalytic esterification reaction, the reaction is repeated, and the use times of the catalyst when the esterification rate is more than 90 percent are calculated.
The results are shown in Table 1.
TABLE 1
| Group of | First use esterification Rate (%) | Number of repetitions (times) |
| Preparation example 1 | 94 | 10 |
| Preparation example 2 | 95 | 10 |
| Preparation example 3 | 97 | 12 |
| Comparative preparation example 1 | 92 | 7 |
| Comparative preparation example 2 | 90 | 6 |
| Comparative preparation example 3 | 87 | / |
| Comparative preparation example 4 | 93 | 7 |
| Comparative preparation example 5 | 82 | / |
| Comparative preparation example 6 | 79 | / |
| Comparative preparation example 7 | 62 | / |
As shown in the table above, the catalysts prepared in preparation examples 1-3 of the invention have better catalytic activity, and the esterification rate can be more than 90% even if the catalyst is repeatedly used for 10-12 times.
Preparation example 4 polyol ester lubricating oil
The preparation method comprises the following steps:
s1, mixing and stirring 7 parts by weight of raw material alcohol, 10 parts by weight of raw material acid and 0.01 part by weight of the catalyst prepared in the preparation example 1 for 10min, heating to 100 ℃, reacting for 3h, and heating and distilling to remove acid to obtain crude ester;
the raw material alcohol comprises isovaleryl tetraol, glycerol and trimethylolethane, and the mass ratio is 5:2:1;
the raw material acid comprises n-decanoic acid and isooctanoic acid, and the mass ratio is 7:2;
s2, washing the crude ester prepared in the step S1 with 2wt% NaOH solution and water respectively for 3 times, and drying the obtained oil phase to obtain the polyol ester lubricating oil with the yield of 93%.
The obtained polyol ester lubricating oil is subjected to infrared spectrum analysis at 1740cm -1 A strong vibration peak appears at 1142cm, which is carbonyl C=O vibration peak -1 The C-O-C vibration peak appears at 3010cm -1 The carboxyl group does not have an-OH vibration absorption peak, and the characteristics of the ester compound are presented. At 2952cm -1 And 1450 cm -1 strong-CH at the site 3 The hydrocarbon vibration peak shows that the polyol ester lubricating oil contains high methyl amount and shows high branching degree.
Preparation example 5 polyol ester lubricating oil
The preparation method comprises the following steps:
s1, mixing and stirring 10 parts by weight of raw material alcohol, 12 parts by weight of raw material acid and 0.1 part by weight of the catalyst prepared in preparation example 2 for 10min, heating to 110 ℃, reacting for 5h, and heating and distilling to remove acid to obtain crude ester;
the raw material alcohol comprises isovaleryl tetraol, glycerol and trimethylolethane, and the mass ratio is 7:3:1;
the raw material acid comprises n-decanoic acid and isooctanoic acid, and the mass ratio is 10:5;
s2, washing the crude ester prepared in the step S1 with 5wt% KOH solution and water respectively for 3 times, and drying the obtained oil phase to obtain the polyol ester lubricating oil with the yield of 91%.
PREPARATION EXAMPLE 6 polyol ester lubricating oil
The preparation method comprises the following steps:
s1, mixing 8.5 parts by weight of raw material alcohol, 11 parts by weight of raw material acid and 0.05 part by weight of the catalyst prepared in the preparation example 1, stirring for 10min, heating to 105 ℃, reacting for 4h, and heating and distilling to remove acid to obtain crude ester;
the raw material alcohol comprises isovaleryl tetraol, glycerol and trimethylolethane, and the mass ratio is 6:2.5:1;
the raw material acid comprises n-decanoic acid and isooctanoic acid, and the mass ratio is 8.5:3.5;
s2, washing the crude ester prepared in the step S1 with a 3.5wt% NaOH solution and water respectively for 3 times, and drying the obtained oil phase to obtain the polyol ester lubricating oil with the yield of 94%.
Comparative preparation example 8
The difference compared to preparation 6 is that the catalyst was prepared from comparative preparation 1.
Comparative preparation example 9
The difference compared to preparation 6 is that the catalyst was prepared from comparative preparation 2.
Comparative preparation example 10
The difference compared to preparation 6 is that the catalyst was prepared from comparative preparation 3.
Comparative preparation 11
The difference compared to preparation 6 is that the catalyst was prepared from comparative preparation 4.
Comparative preparation example 12
The difference compared to preparation 6 is that the catalyst was prepared from comparative preparation 5.
Comparative preparation example 13
The difference compared to preparation 6 is that the catalyst was prepared from comparative preparation 6.
Comparative preparation example 14
The difference compared to preparation 6 is that the catalyst was prepared from comparative preparation 7.
Comparative preparation example 15
The difference compared to preparation 6 is that the catalyst is replaced by an equivalent amount of 98wt% concentrated sulfuric acid.
Comparative preparation example 16
The difference from preparation example 6 is that the starting acid is single n-decanoic acid.
Comparative preparation example 17
The difference compared to preparation example 6 is that the starting acid is a single isooctanoic acid.
Test example 2
The polyol ester lubricating oils prepared in preparation examples 4 to 6 of the present invention and comparative preparation examples 8 to 17 and commercially available similar products were subjected to performance test, and the results are shown in Table 2.
TABLE 2
As is clear from the above table, the polyol ester lubricating oils prepared in preparation examples 4 to 6 of the present invention have suitable viscosity, low trace water content and low total acid/base number.
Example 1
A non-flammable mixed refrigerant suitable for use in a cryogenic system, comprising the following components:
the first component comprises: difluoromethane and tetrafluoroethane in a mass ratio of 5:3;
the second component: 2, 3-tetrafluoropropene;
and a third component: n (N) 2 He, volume ratio 7:5;
and a fourth component: 1,2, 3-heptafluoropropane 1,2,3, 4-nonafluorobutane 1,2, 3-pentafluoropropane, the mass ratio is 3:2:1;
and a fifth component: the mass ratio of the monofluoroethane to the dimethyl ether is 4:2.
The mass ratio of the first component to the second component to the third component to the fourth component to the fifth component is 25:15:2:10:3.
Example 2
A non-flammable mixed refrigerant suitable for use in a cryogenic system, comprising the following components:
the first component comprises: difluoromethane, tetrafluoroethane, mass ratio is 10:5;
the second component: 2, 3-tetrafluoropropene;
and a third component: n (N) 2 He, volume ratio is 12:7;
and a fourth component: 1,2, 3-heptafluoropropane 1,2,3, 4-nonafluorobutane 1,2, 3-pentafluoropropane, the mass ratio is 7:3:2;
and a fifth component: the mass ratio of the monofluoroethane to the dimethyl ether is 7:3.
The mass ratio of the first component to the second component to the third component to the fourth component to the fifth component is 30:20:5:15:5.
Example 3
A non-flammable mixed refrigerant suitable for use in a cryogenic system, comprising the following components:
the first component comprises: difluoromethane, tetrafluoroethane, mass ratio is 7:4;
the second component: 2, 3-tetrafluoropropene;
and a third component: n (N) 2 He, volume ratio of 10:6;
and a fourth component: 1,2, 3-heptafluoropropane 1,2,3, 4-nonafluorobutane 1,2, 3-pentafluoropropane, the mass ratio is 5:2.5:1.5;
and a fifth component: the mass ratio of the monofluoroethane to the dimethyl ether is 5:2.5.
The mass ratio of the first component to the second component to the third component to the fourth component to the fifth component is 27:17:3.5:12:4.
Example 4
In comparison with example 4, 0.5% by weight of nitromethane was added.
Comparative example 1
The difference compared to example 4 is that the first component is a single difluoromethane.
Comparative example 2
The difference compared to example 4 is that the first component is a single tetrafluoroethane.
Comparative example 3
The difference compared to example 4 is that the first component is not added.
Comparative example 4
The difference compared to example 4 is that no second component is added.
Comparative example 5
In comparison with example 4, the third component is a single N 2 。
Comparative example 6
The difference compared to example 4 is that the third component is a single He.
Comparative example 7
The difference compared to example 4 is that no third component is added.
Comparative example 7
The difference compared to example 4 is that the fourth component is not added.
Comparative example 8
The difference compared to example 4 is that the fifth component is a single monofluoroethane.
Comparative example 9
The difference compared to example 4 is that the fifth component is a single dimethyl ether.
Comparative example 10
The difference compared to example 4 is that the fifth component is not added.
Test example 3
The non-flammable mixed refrigerants applicable to low temperature systems, the environmental parameters, physical parameters and thermal properties of R134a prepared in examples 1 to 4 and comparative examples 1 to 10 are shown in Table 3 under the air conditioning conditions of the ARI Standard 520 International Standard, i.e., an evaporation temperature of 7.2 ℃, a condensation temperature of 54.4 ℃, a superheat temperature of 11.1 ℃, a supercooling temperature of 8.3 ℃, and a compressor isentropic efficiency of 0.8.
TABLE 3 Table 3
Annotation: * The ratio of the corresponding parameter values to R134a is shown, where COP is the coefficient of performance.
As shown in the table above, the ODP of the nonflammable mixed refrigerant suitable for the low temperature system prepared in the embodiments 1-4 of the invention is 0, and GWP is less than 1000, which is beneficial to the stable operation of the system. The non-combustible mixed refrigerant suitable for the low-temperature system has the evaporating pressure and condensing pressure equivalent to those of R134a, and can be used for replacing the R134a system without greatly changing the system. Compared with R134a, the incombustible mixed refrigerant suitable for a low-temperature system prepared in examples 1-4 has 21-25% lower cold energy and volume refrigerating energy than R134a, and 22-27% higher COP than R134a.
Test example 4
The nonflammable mixed refrigerants suitable for low temperature systems prepared in examples 1 to 4 and comparative examples 1 to 8 were subjected to an explosion limit test in accordance with ASHRAE 34 standard. Whether the flame is flammable or not is judged by judging the propagation angle of the flame through an observation method. The electrode is non-flammable if the angle between the center of the electrode and the flame propagation to the bottle wall is less than 90 c and flammable if the angle is greater than 90 c.
As a result of the test, the nonflammable mixed refrigerants suitable for low temperature systems prepared in examples 1 to 4 and comparative examples 1 to 8 of the present invention were all nonflammable.
Example 5
A refrigerating system comprises the nonflammable mixed refrigerant suitable for a low-temperature system and prepared in the embodiment 1, wherein the mass ratio of the nonflammable mixed refrigerant to the lubricating oil is 3:6, and the lubricating oil comprises the polyol ester lubricating oil and the polyvinyl ether prepared in the preparation embodiment 4, and the mass ratio of the polyol ester lubricating oil to the polyvinyl ether is 7:1.
Example 6
A refrigerating system comprises the nonflammable mixed refrigerant which is prepared in the embodiment 2 and is suitable for a low-temperature system, and lubricating oil, wherein the mass ratio of the nonflammable mixed refrigerant to the lubricating oil is 5:9, and the lubricating oil comprises the polyol ester lubricating oil and the polyvinyl ether which are prepared in the preparation embodiment 5, and the mass ratio of the polyol ester lubricating oil to the polyvinyl ether is 10:2.
Example 7
A refrigeration system comprising the nonflammable mixed refrigerant suitable for a low temperature system and the lubricating oil prepared in example 3 in a mass ratio of 4:7, wherein the lubricating oil comprises the polyol ester lubricating oil and the polyvinyl ether prepared in preparation example 6 in a mass ratio of 8:1.5.
Example 8
A refrigeration system comprising the nonflammable mixed refrigerant suitable for a low temperature system and the lubricating oil prepared in example 4 in a mass ratio of 4:7, wherein the lubricating oil comprises the polyol ester lubricating oil and the polyvinyl ether prepared in preparation example 6 in a mass ratio of 8:1.5.
The foregoing description of the preferred embodiments of the invention is not intended to be limiting, but rather is intended to cover all modifications, equivalents, alternatives, and improvements that fall within the spirit and scope of the invention.
Claims (5)
1. Use of a non-flammable mixed refrigerant suitable for use in a cryogenic system in a refrigeration system, said non-flammable mixed refrigerant suitable for use in a cryogenic system comprising:
a first component: difluoromethane, tetrafluoroethane;
and a second component: 2, 3-tetrafluoropropene;
and a third component: n (N) 2 、He；
And a fourth component: 1, 2-pentafluoropropane, 1,2, 3-heptafluoropropane 1, 3-hexafluoropropane, 1, 2-tetrafluoropropane 1, 3-hexafluoropropane 1, 2-tetrafluoropropane 1,2, 3-heptafluorobutane, 1,1,1,2,2,4,4,4-octafluorobutane 1,2, 3-pentafluoropropane, 1,2, 3-pentafluoropropane at least one of 1,2,3, 4-octafluorobutane and 1,1,1,2,2,3,3,4-octafluorobutane;
and a fifth component: monofluoroethane and dimethyl ether;
the refrigeration system also comprises lubricating oil;
the lubricating oil comprises polyol ester lubricating oil and polyvinyl ether, wherein the mass ratio of the polyol ester lubricating oil to the polyvinyl ether is 7-10:1-2; the preparation method of the polyol ester lubricating oil comprises the following steps:
s1, mixing raw material alcohol, raw material acid and a catalyst, heating for reaction, and heating for distillation to remove the acid to obtain crude ester;
s2, sequentially washing the crude ester prepared in the step S1 with alkali liquor and water, and drying to obtain polyol ester lubricating oil;
the raw material alcohol comprises isovaleryl tetraol, glycerol and trimethylolethane, and the mass ratio is 5-7:2-3:1;
the raw material acid comprises n-capric acid and isooctanoic acid, and the mass ratio is 7-10:2-5;
heating to 100-110 ℃ for 3-5h;
the preparation method of the catalyst comprises the following steps:
preparation of Si-Ti-Zr oxide nanospheres: dissolving tetraethoxysilane and tetrabutyl titanate in an organic solvent, stirring and mixing uniformly, adding an aqueous solution containing zirconium chloride, an emulsifying agent and a pore-forming agent, emulsifying, dropwise adding ammonia water, stirring and reacting, centrifuging, washing and drying to obtain Si-Ti-Zr oxide nanospheres;
t2. preparation of magnetic Si-Ti-Zr oxide nanospheres: dissolving ferric chloride and ferrous chloride in water, adding the Si-Ti-Zr oxide nanospheres prepared in the step T1, dropwise adding ammonia water, stirring for reaction, separating by a magnet, washing and drying to obtain the magnetic Si-Ti-Zr oxide nanospheres;
T3.La 2 O 3 /MoO 3 is deposited by: and (3) dissolving lanthanum chloride and ammonium molybdate in water, adding the magnetic Si-Ti-Zr oxide nanospheres prepared in the step (T2), carrying out impregnation reaction, washing, drying and calcining to obtain the catalyst.
2. The use according to claim 1, wherein the mass ratio of the first component, the second component, the third component, the fourth component, and the fifth component is 25-30:15-20:2-5:10-15:3-5.
3. The use according to claim 1, wherein, the fourth component comprises 1,2, 3-heptafluoropropane 1,2,3, 4-nonafluorobutane, 1,2, 3-pentafluoropropane, the mass ratio is 3-7:2-3:1-2.
4. The use according to claim 1, wherein the mass ratio of difluoromethane, tetrafluoroethane in the first component is 5-10:3-5; n in the third component 2 The volume ratio of He is 7-12:5-7; the mass ratio of the monofluoroethane to the dimethyl ether in the fifth component is 4-7:2-3.
5. The use of claim 1, wherein the refrigerant further comprises a stabilizer selected from at least one of alkyl aryl ether, thiol, lactone, thioether, nitromethane, alkylsilane, benzophenone derivative, diethylene terephthalic acid, or diphenyl terephthalic acid.
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