Preparation method of polyether nonionic surfactant

Abstract

The invention discloses a preparation method of a polyether nonionic surfactant, which is characterized in that a mass transfer process of addition reaction of fatty alcohol and ethylene oxide is obviously enhanced by adopting a venturi ejector, and the problems of long reaction time, need of segmented temperature control and the like caused by dependence on slow diffusion of EO (Ethylene Oxide) in the traditional kettle reaction are solved. EO can be uniformly dispersed into an alcohol-catalyst system within millisecond-level time, local hot spots and concentration gradient are thoroughly eliminated, the effect is extremely remarkable, and the reaction induction period is shortened. In a traditional method, EO is intensively added, heat release is easy to control, EO gradual mixing is achieved in a Venturi mode, and the reaction heat release rate is controllable. The Venturi structure replaces traditional batch feeding, the productivity is improved, and the reaction time is shortened. According to the catalyst, zero-residue design is adopted, and the SiO2 shell layer realizes complete wrapping of active components, so that dissolution is prevented; after the reaction, the catalyst can be completely separated only by simple filtration, and a filter cake can be recycled after being washed by ethanol, dried and activated.

Description

Technical Field

[0001] The present invention relates to the technical field of chemical industry, in particular to a method for preparing a polyether nonionic surfactant. Background Art

[0002] Polyether nonionic surfactants (such as fatty alcohol polyoxyethylene ether, AEO) exhibit excellent emulsification, dispersing, wetting and penetration properties due to their unique molecular structure, with a hydrophobic hydrocarbon chain (such as fatty alcohol) at one end and a hydrophilic polyoxyethylene ether chain at the other. These properties make them indispensable key additives in many industrial fields. Textile printing and dyeing: They are highly efficient refining agents, leveling agents and penetrants that can effectively remove fiber impurities, promote uniform adsorption and penetration of dyes, and improve color fastness and brightness. Pesticide formulations: As core emulsifiers, they can stably disperse oil-soluble pesticide technicals in water to form a uniform emulsion, thereby improving efficacy, reducing pesticide damage, and facilitating spraying and application. Daily chemical products: They are widely used as base surfactants in detergents, shampoos, shower gels, and cosmetics, providing mild detergency, rich foam and good compatibility. Industrial cleaning: They are used to formulate high-efficiency cleaning agents in metal processing, the petroleum industry and other fields to remove grease and dirt. Papermaking: They are used as resin dispersion control agents to reduce resin obstacles in the production process.

[0003] Its outstanding advantages are low foaming, hard water resistance, and relatively good biodegradability. Moreover, its performance can be precisely "customized" by adjusting the hydrophobic group chain length and the number of ethylene oxide (EO) additions to meet the specific needs of different application scenarios (such as the hydrophile-lipophile balance (HLB). This greatly broadens its scope of application and consolidates its important position in the field of surfactants.

[0004] Traditional industrial production mainly uses base catalysis (such as NaOH, KOH) to ethoxylate fatty alcohols with ethylene oxide in a high-pressure reactor. However, this method has significant drawbacks:

[0005] 1. Side reactions are difficult to control: Under strong alkaline conditions, ethylene oxide is prone to isomerization to produce acetaldehyde, which in turn triggers side reactions, resulting in a wider molecular weight distribution of the product and a high free alcohol content, affecting product purity and application performance.

[0006] 2. Catalyst residue problem: Homogeneous alkaline catalysts require subsequent neutralization and filtration steps to remove, which not only increases energy consumption but also introduces inorganic salt residues, limiting the product's application in high-purity applications.

[0007] 3. Low reaction efficiency: The EO diffusion rate in traditional kettle reactors is slow, the reaction time is long, and the material needs to be added slowly in sections to avoid local overheating, which restricts production efficiency.

[0008] Therefore, it is necessary to develop an efficient, highly selective, and recyclable catalytic system and combine it with an efficient mixing reactor to achieve green and high-purity preparation of polyether surfactants. Summary of the Invention

[0009] The present invention addresses various deficiencies in the prior art and provides a method for preparing a polyether nonionic surfactant. The present invention is achieved through the following technical solutions:

[0010] The present invention discloses a method for preparing a polyether nonionic surfactant, which is characterized by comprising the following steps:

[0011] 1) Preparation of composite catalyst MgO-CeO2 / La2O3-Al2O3@SiO2;

[0012] 2) Adding fatty alcohol and composite catalyst MgO-CeO2 / La2O3-Al2O3@SiO2 into a reactor, sealing the reactor lid, and then introducing nitrogen for displacement. After the displacement is completed, the reaction system is heated to 80-90°C for dehydration;

[0013] 3) introducing the fatty alcohol and the composite catalyst MgO-CeO2 / La2O3-Al2O3@SiO2 mixed solution into the contraction section of the venturi ejector and into the reactor via a metering pump;

[0014] 4) Ethylene oxide is sucked in by the negative pressure at the throat of the Venturi ejector, fully mixed with the fatty alcohol, and enters the reactor to obtain a mixture;

[0015] 5) The mixture is sprayed into a reactor and reacted at 100-120°C and 0.4-0.6 MPa pressure;

[0016] 6) After the reaction is completed, the product is filtered and the filtrate is distilled under reduced pressure to obtain the product fatty alcohol polyoxyethylene ether; the filter cake is washed with anhydrous ethanol and then dried, and subsequently recycled.

[0017] As a further improvement, the specific method for preparing the composite catalyst MgO-CeO2 / La2O3-Al2O3@SiO2 in step 1) of the present invention is:

[0018] The γ-Al2O3 is immersed in a 10-20% lanthanum nitrate solution, dried and calcined at 400-500°C for 4-6 hours to obtain a La2O3 / Al2O3 carrier; the carrier is added to a mixed liquid of Mg(NO3)2 and Ce(NO3)3, NH4HCO3 is added dropwise to a pH of 9-10, dried and calcined at 500-600°C under nitrogen for 2-4 hours; the carrier is immersed in an ethanol aqueous solution and ethyl orthosilicate is added dropwise to form MgO-CeO2 / La2O3-Al2O3@SiO2.

[0019] As a further improvement, the fatty alcohol in step 2) of the present invention is lauryl alcohol C12, myristyl alcohol C14, and palmityl alcohol C16.

[0020] As a further improvement, the flow rate into the contraction section of the Venturi reactor in step 3) of the present invention is 10-30 m / s.

[0021] As a further improvement, in step 3) of the present invention, the mass of the composite catalyst is 1-2% of the mass of the fatty alcohol.

[0022] As a further improvement, the analysis results of the fatty alcohol polyoxyethylene ether prepared according to the present invention are as follows: the amount of PEG byproducts is less than 0.2%, the EO conversion rate is 99.4%, the molecular weight distribution index PDI = 1.01-1.08, and the catalyst activity is maintained at 97% after 50 cycles.

[0023] The beneficial effects of the present invention are as follows:

[0024] 1. By employing a Venturi ejector, this invention significantly enhances the mass transfer process in the addition reaction of fatty alcohols and ethylene oxide (EO), overcoming the long reaction times and staged temperature control required by traditional kettle reactions, which rely on slow diffusion of EO. Specifically, the fatty alcohol and catalyst mixture flows through the constricted section of the Venturi tube at a high speed of 18–22 m / s, generating a strong negative pressure at the throat, instantly drawing in the EO and achieving intense turbulent mixing at the micron level. This design enables uniform dispersion of EO throughout the alcohol-catalyst system within milliseconds, completely eliminating local hot spots and concentration gradients. This significantly shortens the reaction induction period. Furthermore, this method operates under mild conditions, with reaction temperatures (100–120°C) and pressures (0.4–0.6 MPa) lower than those of traditional atmospheric pressure methods (160–180°C), resulting in reduced energy consumption. While concentrated EO addition in traditional methods can lead to uncontrolled exothermic reaction, the Venturi achieves progressive EO mixing, enabling a controlled exothermic rate. The Venturi configuration replaces traditional batch addition, increasing production capacity and shortening reaction times.

[0025] 2. Traditional base catalysis methods easily cause ethylene oxide to isomerize to acetaldehyde under a strong alkaline environment, triggering side reactions such as chain transfer, resulting in a wide molecular weight distribution of the product. The present invention adopts an innovative composite catalyst MgO-CeO2 / La2O3-Al2O3@SiO2, which significantly improves the product purity and the uniformity of the molecular weight distribution. The catalyst effectively regulates the ring-opening reaction path through acid-base synergistic catalysis (MgO provides weak alkaline sites, CeO2 / La2O3 provides acidic sites), significantly inhibits the isomerization of EO, and thus greatly reduces the generation of acetaldehyde, the source of side reactions. At the same time, the core-shell confinement effect (the porous SiO2 shell limits the migration of active components to form active sites of uniform size) ensures that the EO addition reaction strictly follows the step-by-step polymerization mechanism, making the product molecular weight distribution narrower. In addition, the catalyst adopts a zero-residue design: the SiO2 shell achieves complete encapsulation of the active components to prevent dissolution; after the reaction, the catalyst can be completely separated by simple filtration, and the filter cake can be recycled after washing with ethanol, drying and activation. This not only avoids the drawbacks of traditional homogeneous base catalysts that require neutralization and filtration and introduce inorganic salt contamination, but also eliminates the need for complex post-processing of the product. DETAILED DESCRIPTION

[0026] The technical solution of the present invention is further described in detail below in conjunction with specific embodiments, but the scope of the present invention is not limited to the embodiments.

[0027] Example 1

[0028] 1) γ-Al2O3 was impregnated in a 15% lanthanum nitrate solution, dried, and calcined at 400°C for 5 hours to obtain a La2O3 / Al2O3 carrier; the carrier was added to a mixed liquid of Mg(NO3)2 and Ce(NO3)3, NH4HCO3 was added dropwise to a pH of 9.5, and dried, and calcined at 550°C under nitrogen for 3 hours; the carrier was impregnated in an ethanol aqueous solution and ethyl orthosilicate was added dropwise to form MgO-CeO2 / La2O3-Al2O3@SiO2;

[0029] 2) Place 186g of lauryl alcohol C12 and 1.86g of the composite catalyst into a reaction kettle and seal the lid. Nitrogen is then introduced for displacement. After displacement, the reaction system is heated to 80°C for dehydration.

[0030] 3) The mixed liquid is fed into the reactor through the constriction section of the venturi ejector at a flow rate of 10 m / s via a metering pump;

[0031] 4) 396 g of ethylene oxide was sucked in by the negative pressure at the throat of the Venturi ejector, fully mixed with the fatty alcohol, and entered the reactor to obtain a mixture;

[0032] 5) The mixture was sprayed into a reactor and reacted at 100°C and 0.4 MPa pressure;

[0033] 6) After the reaction is completed, the product is filtered, and the filtrate is distilled under reduced pressure to obtain the product fatty alcohol polyoxyethylene ether, and the filter cake is washed with anhydrous ethanol and dried, and subsequently recycled.

[0034] Analysis of results: the amount of PEG by-products was less than 0.4%, the EO conversion rate was 96%, the molecular weight distribution index PDI was 1.06, and the activity of the catalyst was maintained at 91% after 50 cycles.

[0035] Example 2

[0036] 1) γ-Al2O3 was impregnated in a 10% lanthanum nitrate solution, dried, and calcined at 500°C for 4 hours to obtain a La2O3 / Al2O3 carrier; the carrier was added to a mixed liquid of Mg(NO3)2 and Ce(NO3)3, NH4HCO3 was added dropwise to a pH of 9, and dried, and calcined at 600°C under nitrogen for 2 hours; the carrier was impregnated in an ethanol aqueous solution and ethyl orthosilicate was added dropwise to form MgO-CeO2 / La2O3-Al2O3@SiO2;

[0037] 2) Place 214g of myristyl alcohol C14 and 3.21g of the composite catalyst into a reaction kettle and seal the lid. Nitrogen is then introduced to perform a displacement operation. After the displacement is complete, the reaction system is heated to 90°C for dehydration.

[0038] 3) The mixture is fed into the reactor through a metering pump at a flow rate of 20 m / s through the contraction section of the venturi ejector;

[0039] 4) 396 g of ethylene oxide was sucked in by the negative pressure at the throat of the Venturi ejector, fully mixed with the fatty alcohol, and entered the reactor to obtain a mixture;

[0040] 5) The mixture was sprayed into a reactor and reacted at 110°C and 0.5 MPa pressure;

[0041] 6) After the reaction is completed, the product is filtered, and the filtrate is distilled under reduced pressure to obtain the product fatty alcohol polyoxyethylene ether, and the filter cake is washed with anhydrous ethanol and dried, and subsequently recycled.

[0042] Analysis of the results showed that the amount of PEG by-products was less than 0.3%, the EO conversion rate was 99.1%, the molecular weight distribution index (PDI) was 1.03, and the activity of the catalyst was maintained at 95% after 50 cycles.

[0043] Example 3

[0044] 1) γ-Al2O3 was impregnated in a 10% lanthanum nitrate solution, dried, and calcined at 500°C for 4 hours to obtain a La2O3 / Al2O3 carrier; the carrier was added to a mixed liquid of Mg(NO3)2 and Ce(NO3)3, NH4HCO3 was added dropwise to a pH of 9, and dried, and calcined at 600°C under nitrogen for 2 hours; the carrier was impregnated in an ethanol aqueous solution and ethyl orthosilicate was added dropwise to form MgO-CeO2 / La2O3-Al2O3@SiO2;

[0045] 2) Place 186g of lauryl alcohol C12 and 1.86g of the composite catalyst into a reaction kettle and seal the lid. Nitrogen is then introduced for displacement. After displacement, the reaction system is heated to 90°C for dehydration.

[0046] 3) The mixture is fed into the reactor through a metering pump at a flow rate of 20 m / s through the contraction section of the venturi ejector;

[0047] 4) 396 g of ethylene oxide was sucked in by the negative pressure at the throat of the Venturi ejector, fully mixed with the fatty alcohol, and entered the reactor to obtain a mixture;

[0048] 5) The mixture was sprayed into a reactor and reacted at 110°C and 0.5 MPa pressure;

[0049] 6) After the reaction is completed, the product is filtered, and the filtrate is distilled under reduced pressure to obtain the product fatty alcohol polyoxyethylene ether, and the filter cake is washed with anhydrous ethanol and dried, and subsequently recycled.

[0050] Result analysis: the amount of PEG by-products was less than 0.2%, the EO conversion rate was 99.4%, the molecular weight distribution index PDI was 1.01, and the activity of the catalyst was maintained at 97% after 50 cycles.

[0051] Example 4

[0052] 1) γ-Al2O3 was impregnated in a 10% lanthanum nitrate solution, dried, and calcined at 500°C for 4 hours to obtain a La2O3 / Al2O3 carrier; the carrier was added to a mixed liquid of Mg(NO3)2 and Ce(NO3)3, NH4HCO3 was added dropwise to a pH of 9, and dried, and calcined at 600°C under nitrogen for 2 hours; the carrier was impregnated in an ethanol aqueous solution and ethyl orthosilicate was added dropwise to form MgO-CeO2 / La2O3-Al2O3@SiO2;

[0053] 2) Place 242g of palm alcohol C16 and 4.84g of the composite catalyst into a reaction kettle and seal the lid. Nitrogen is then introduced to perform a displacement operation. After the displacement is complete, the reaction system is heated to 90°C for dehydration.

[0054] 3) The mixture is fed into the reactor through a metering pump at a flow rate of 20 m / s through the contraction section of the venturi ejector;

[0055] 4) 396 g of ethylene oxide was sucked in by the negative pressure at the throat of the Venturi ejector, fully mixed with the fatty alcohol, and entered the reactor to obtain a mixture;

[0056] 5) The mixture was sprayed into a reactor and reacted at 110°C and 0.5 MPa pressure;

[0057] 6) After the reaction is completed, the product is filtered, and the filtrate is distilled under reduced pressure to obtain the product fatty alcohol polyoxyethylene ether, and the filter cake is washed with anhydrous ethanol and dried, and subsequently recycled.

[0058] Analysis of results: the amount of PEG by-products was less than 0.4%, the EO conversion rate was 99.2%, the molecular weight distribution index PDI was 1.04, and the activity of the catalyst was maintained at 93% after 50 cycles.

[0059] Example 5

[0060] 1) impregnating γ-Al2O3 in a 10-20% lanthanum nitrate solution, drying, and calcining at 550°C for 6 hours to obtain a La2O3 / Al2O3 carrier; adding the carrier to a mixed liquid of Mg(NO3)2 and Ce(NO3)3, adding NH4HCO3 dropwise until the pH is 10, drying, and calcining at 500°C under nitrogen for 4 hours; impregnating the carrier in an ethanol aqueous solution and adding tetraethyl orthosilicate dropwise to form MgO-CeO2 / La2O3-Al2O3@SiO2;

[0061] 2) Place 242g of palm alcohol C16 and 4.84g of the composite catalyst into a reaction kettle and seal the lid. Nitrogen is then introduced to perform a displacement operation. After the displacement is complete, the reaction system is heated to 85°C for dehydration.

[0062] 3) feeding the mixed liquid into the reactor through the constriction section of the venturi ejector at a flow rate of 30 m / s via a metering pump to obtain a mixture;

[0063] 4) 550g of ethylene oxide is sucked in by the negative pressure at the throat of the Venturi ejector and fully mixed with the fatty alcohol;

[0064] 5) The mixture was sprayed into a reactor and reacted at 120°C and 0.6 MPa pressure;

[0065] 6) After the reaction is completed, the product is filtered, and the filtrate is distilled under reduced pressure to obtain the product fatty alcohol polyoxyethylene ether, and the filter cake is washed with anhydrous ethanol and dried, and subsequently recycled.

[0066] Analysis of the results showed that the amount of PEG by-products was less than 0.6%, the EO conversion rate was 97%, the molecular weight distribution index (PDI) was 1.08, and the activity of the catalyst was maintained at 95% after 50 cycles.

[0067] Comparative Example 1

[0068] The added catalyst is MgO@SiO 2， The remaining conditions were the same as those in Example 3. The analysis of the results showed that the amount of PEG by-products was less than 5.1%, the EO conversion rate was 70%, the molecular weight distribution index (PDI) was 1.18, and the activity of the catalyst after 10 cycles was less than 90%.

[0069] Comparative Example 2

[0070] The added catalyst is CeO2@SiO 2， The remaining conditions were the same as those in Example 3. The analysis of the results showed that the amount of PEG by-products was less than 6.1%, the EO conversion rate was 72%, the molecular weight distribution index (PDI) was 1.15, and the activity of the catalyst after 10 cycles was less than 90%.

[0071] Comparative Example 3

[0072] The added catalyst is La2O3@SiO 2， The remaining conditions were the same as those in Example 3. The analysis of the results showed that the amount of PEG by-products was less than 5.4%, the EO conversion rate was 75%, the molecular weight distribution index (PDI) was 1.15, and the activity of the catalyst after 10 cycles was less than 90%.

[0073] Comparative Example 4

[0074] The added catalyst is Al2O3@SiO 2， The remaining conditions were the same as those in Example 3. The analysis of the results showed that the amount of PEG by-products was less than 6.9%, the EO conversion rate was 73%, the molecular weight distribution index (PDI) was 1.20, and the activity of the catalyst after 10 cycles was less than 90%.

[0075] Comparative Example 5

[0076] The added catalyst is MgO / La2O3-Al2O3@SiO 2， The remaining conditions were the same as those in Example 3. The results were analyzed as follows: the amount of PEG by-products was <4.2%, the EO conversion rate was 78%, the molecular weight distribution index PDI = 1.10, and the activity of the catalyst after 30 cycles was <90%.

[0077] Comparative Example 6

[0078] The added catalyst is MgO-CeO2 / La2O3@SiO 2，The remaining conditions were the same as those in Example 3. The analysis of the results showed that the amount of PEG by-products was less than 4.7%, the EO conversion rate was 79%, the molecular weight distribution index (PDI) was 1.11, and the activity of the catalyst after 30 cycles was less than 90%.

[0079] Comparative Example 7

[0080] The added catalyst is MgO-CeO2 / La2O3-Al2O 3， The remaining conditions were the same as those in Example 3. The analysis of the results showed that the amount of PEG by-products was less than 5.3%, the EO conversion rate was 75%, the molecular weight distribution index (PDI) was 1.17, and the activity of the catalyst after 10 cycles was less than 90%.

[0081] Comparative Example 8

[0082] The added catalyst is MgO-CeO2 / La2O3-Al2O3@TiO 2， The remaining conditions were the same as those in Example 3. The analysis of the results showed that the amount of PEG by-products was less than 2.1%, the EO conversion rate was 91%, the molecular weight distribution index (PDI) was 1.08, and the activity of the catalyst was maintained at 80% after 50 cycles.

[0083] It can be seen that Control Examples 1-4 are single-component metal oxide catalysts, Control Examples 5 and 6 are catalysts with missing key components, Control Example 7 is a catalyst without a carrier, and Control Example 8 is a catalyst with a different carrier structure. Compared with Example 3, the catalyst of Example 3 is significantly superior to the control examples in by-product suppression, conversion rate, molecular weight distribution and cycle life due to the synergistic effect of the unique carrier (SiO2) and the multi-active components, and has the best comprehensive performance.

[0084] Comparative Example 9 (Traditional Method)

[0085] 1) Add 385g of lauryl alcohol and 1.5g of potassium hydroxide into a reaction kettle, seal the kettle, introduce nitrogen three times, and then heat to 80°C for dehydration;

[0086] 2) Raise the temperature to 140°C and add 35g of ethylene oxide, then continue to raise the temperature to 160°C and add 540g of ethylene oxide;

[0087] 3) Aging until the pressure in the kettle no longer decreases, cooling to below 70° C. and discharging to obtain the product fatty alcohol polyoxyethylene ether.

[0088] It can be seen that compared with Example 3, Control Example 9 uses a traditional method, which has a high reaction temperature, high energy consumption, and long reaction time. The results are analyzed as follows: the amount of PEG by-products is 4.2%, the EO conversion rate is 80%, and the molecular weight distribution index PDI = 1.21.

[0089] Comparative Example 10 (without Venturi ejector)

[0090] 1) Preparation of MgO-CeO2 / La2O3-Al2O3@SiO2 composite catalyst;

[0091] 2) Place 186g of lauryl alcohol and 1.86g of the composite catalyst into the reactor and seal the lid. Nitrogen is then introduced and replaced three times. After replacement, the reaction system is heated to 80°C for dehydration.

[0092] 3) The mixture was introduced into a kettle reactor, 396 g of ethylene oxide was introduced, and the reaction was carried out at 110° C. and 0.5 MPa pressure;

[0093] 4) After the reaction is completed, the product is filtered, and the filtrate is distilled under reduced pressure to obtain the product fatty alcohol polyoxyethylene ether, and the filter cake is dried with anhydrous ethanol and subsequently recycled.

[0094] It can be seen that compared with Example 3, Control Example 10 uses a traditional reactor, and the results are analyzed as follows: the amount of PEG by-products is less than 4.2%, the EO conversion rate is 78%, the molecular weight distribution index PDI = 1.16, and the catalyst activity is maintained at 70% after 50 cycles.

[0095] Finally, it should be noted that the above examples are merely specific implementation examples of the present invention. Obviously, the present invention is not limited to the above examples and is subject to numerous variations. All variations that can be directly derived or conceived by a person of ordinary skill in the art from the disclosure of the present invention should be considered within the scope of protection of the present invention.

Claims

1. A method for preparing a polyether nonionic surfactant, characterized in that The following steps are involved: 1) Preparation of composite catalyst MgO-CeO2 / La2O3-Al2O3@SiO2; 2) Adding fatty alcohol and composite catalyst MgO-CeO2 / La2O3-Al2O3@SiO2 into a reactor, sealing the reactor lid, and then introducing nitrogen for displacement. After the displacement is completed, the reaction system is heated to 80-90°C for dehydration; 3) introducing the fatty alcohol and the composite catalyst MgO-CeO2 / La2O3-Al2O3@SiO2 mixed solution into the contraction section of the venturi ejector and into the reactor via a metering pump; 4) Ethylene oxide is sucked in by the negative pressure at the throat of the Venturi ejector, fully mixed with the fatty alcohol, and enters the reactor to obtain a mixture; 5) The mixture is sprayed into a reactor and reacted at 100-120°C and 0.4-0.6 MPa pressure; 6) After the reaction is completed, the product is filtered and the filtrate is distilled under reduced pressure to obtain the product fatty alcohol polyoxyethylene ether; The filter cake is washed with anhydrous ethanol and then dried for subsequent recycling.

2. The method for preparing a polyether nonionic surfactant according to claim 1, wherein: The specific method for preparing the composite catalyst MgO-CeO2 / La2O3-Al2O3@SiO2 in step 1) is: impregnating γ-Al2O3 in a 10-20% lanthanum nitrate solution, drying, and calcining at 400-500°C for 4-6 hours to obtain a La2O3 / Al2O3 carrier; Add the carrier to the mixed liquid of Mg(NO3)2 and Ce(NO3)3, add NH4HCO3 dropwise until the pH is 9-10, dry and calcine at 500-600℃ under nitrogen for 2-4h; The support was immersed in an ethanol aqueous solution and ethyl orthosilicate was added dropwise to form MgO-CeO2 / La2O3-Al2O3@SiO2.

3. The method for preparing a polyether nonionic surfactant according to claim 1 or 2, wherein: The fatty alcohol in step 2) is lauryl alcohol C12, myristyl alcohol C14, and palmityl alcohol C16.

4. The method for preparing a polyether nonionic surfactant according to claim 3, wherein: The flow rate of the flow into the contraction section of the venturi reactor in step 3) is 10-30 m / s.

5. The method for preparing a polyether nonionic surfactant according to claim 4, wherein: In step 3), the mass of the composite catalyst is 1-2% of the mass of the fatty alcohol.

6. The method for preparing the polyether nonionic surfactant according to claim 1, 2, 4 or 5, wherein: The analysis results of the prepared fatty alcohol polyoxyethylene ether are as follows: the amount of PEG byproducts is less than 0.2%, the EO conversion rate is 99.4%, the molecular weight distribution index PDI is 1.01-1.08, and the activity of the catalyst is maintained at 97% after 50 cycles.