Disclosure of Invention
The invention provides a preparation method of a composite solid acid catalyst and application of the composite solid acid catalyst in alcohol ether synthesis, which can improve the activity of the catalyst, reduce the reaction temperature, improve the use times of the catalyst and reduce the weight loss of the catalyst in the use process.
In order to solve the technical problems, the technical scheme adopted by the invention is as follows:
a process for preparing the composite solid-acid catalyst includes preparing mixed powder, preparing microballs, preparing solid-carried acid liquid, preparing coated microballs and secondary coating.
The preparation method comprises the following steps of preparing mixed powder by mixing bentonite, zeolite powder and boron nitride according to a mass ratio of 3-6: 1, ball milling after uniformly mixing, and controlling the ball-material ratio in the ball milling process to be 20-30: 1, the rotating speed is 400-500rpm, the ball milling time is 3-4h, and mixed powder is obtained after the ball milling is finished.
The preparation method comprises the steps of uniformly mixing mixed powder, citric acid, acetic acid and chitin to obtain primary mixed liquid, controlling the temperature of the primary mixed liquid to be 50-60 ℃, then slowly dropwise adding a cross-linking liquid into the primary mixed liquid while carrying out ultrasonic oscillation, controlling the frequency of the ultrasonic oscillation to be 20-30kHz, controlling the dropwise adding time to be 30-40min, continuing the ultrasonic oscillation for 20-30min after the dropwise adding is finished to obtain mixed liquid, carrying out spray drying on the mixed liquid, controlling the temperature of an air inlet to be 110-120 ℃ and the temperature of an air outlet to be 70-80 ℃ in the spray drying process, and obtaining the microspheres after the spray drying is finished.
Wherein the mass ratio of the mixed powder, the citric acid, the acetic acid and the chitin is 25-30: 10-15: 15-20: 3-5.
Wherein the mass ratio of the primary mixed solution to the cross-linking solution is 1: 1.5-2.
The cross-linking liquid comprises the following components in parts by weight: 30-35 parts of diethyl ether, 15-20 parts of glutaraldehyde, 5-8 parts of zwitterionic polyacrylamide and 1-2 parts of ethyl acrylate.
The preparation method of the immobilized acid solution comprises the steps of adding nano activated carbon, aluminum chloride, polyvinyl alcohol 1788 and nano alumina into 1.5-2% by mass of phosphotungstic acid aqueous solution, and then stirring at the temperature of 50-60 ℃ for 2-2.5 hours at the stirring speed of 200-250rpm to obtain the immobilized acid solution.
Wherein, the mass ratio of phosphotungstic acid aqueous solution, nano activated carbon, aluminum chloride and polyvinyl alcohol 1788 to nano alumina is 30-35: 10-15: 3-5: 7-10: 15-20.
The particle size of the nano activated carbon is 80-100 nm.
The particle size of the nano alumina is 50-80 nm.
Preparing the coated microspheres by mixing the immobilized acid solution and the microspheres in a mass ratio of (2-3): 1, uniformly mixing, performing microwave oscillation, controlling the intensity of the microwave oscillation to be 50-70W, controlling the time of the microwave oscillation to be 30-40min, performing high-pressure treatment after the microwave oscillation is finished, controlling the temperature of the high-pressure treatment to be 65-70 ℃, the pressure of the high-pressure treatment to be 80-100MPa, and the time of the high-pressure treatment to be 10-15min, obtaining a wrapping liquid after the high-pressure treatment is finished, and then performing vacuum spray drying on the wrapping liquid, controlling the vacuum degree in the vacuum spray drying process to be 0.01-0.02MPa, controlling the air inlet temperature to be 110-.
And in the secondary coating, coating the microspheres and the acid gel according to a mass ratio of 1: 3-4, uniformly mixing, freezing, spray-drying, controlling the temperature of a spray freezing air inlet of the freezing spray-drying to be-20 to-10 ℃, the temperature of an air outlet to be-30 to-20 ℃, the temperature of a cold trap to be-60 to-50 ℃, the spray pressure to be 20-30bar, and obtaining the composite solid acid catalyst after the freezing spray-drying is finished.
The acidic gel comprises the following components in parts by weight: 30-35 parts of deionized water, 10-12 parts of hyaluronic acid, 7-10 parts of alginic acid, 3-5 parts of xanthan gum, 2-4 parts of acetic acid and 1-2 parts of poly (diallyldimethylammonium chloride).
The molecular weight of the hyaluronic acid is 1000-3000 kDa.
The application of the composite solid acid catalyst in alcohol ether synthesis is characterized by adding absolute ethyl alcohol and the composite solid acid catalyst into a reaction kettle, mixing, vacuumizing the reaction kettle until the vacuum degree is 60-80Pa, introducing nitrogen into the reaction kettle, controlling the gas pressure of the introduced nitrogen to be 0.06-0.08MPa, controlling the temperature of the reaction kettle to be 40-50 ℃, controlling the stirring speed to be 200-300rpm, then adding ethylene oxide, controlling the adding time of the ethylene oxide to be 1-1.5h, and continuing to react for 1.5-2h after the addition is finished to obtain ethylene glycol ether.
Wherein the molar ratio of the absolute ethyl alcohol to the ethylene oxide is 1-1.06: 1.
Wherein the mass ratio of the composite solid acid catalyst to the absolute ethyl alcohol is 1: 43.33-46.
Compared with the prior art, the invention has the beneficial effects that:
(1) according to the composite solid acid catalyst prepared by the invention, high-pressure treatment is carried out in the step of coating microspheres, and the solid acid catalyst is coated for the second time, so that the catalytic activity can be improved, the reaction temperature can be reduced, and the reaction temperature of absolute ethyl alcohol and ethylene oxide can be reduced to 40-50 ℃;
(2) according to the composite solid acid catalyst prepared by the invention, through ultrasonic oscillation in the microsphere preparation step, high-pressure treatment in the microsphere wrapping step and secondary wrapping of the solid acid catalyst, the yield and purity of ethylene glycol ethyl ether in the reaction of absolute ethyl alcohol and ethylene oxide can be improved, the yield of ethylene glycol ethyl ether is improved to 89.6-91.5%, and the purity is improved to 87.2-90.4%;
(3) the composite solid acid catalyst prepared by the invention can improve the using times of the catalyst by carrying out high-pressure treatment in the step of coating microspheres and carrying out secondary coating on the solid acid catalyst, and after the composite solid acid catalyst prepared by the invention is repeatedly used for 30 times, the yield of ethylene glycol ethyl ether can still reach 88.7-91.1%;
(4) the composite solid acid catalyst prepared by the invention can reduce the weight loss in the using process of the catalyst by carrying out high-pressure treatment in the step of coating microspheres and carrying out secondary coating on the solid acid catalyst, and after the composite solid acid catalyst prepared by the invention is repeatedly used for 30 times, the mass loss of ethylene glycol ethyl ether is 4.6-8%.
Detailed Description
In order to more clearly understand the technical features, objects, and effects of the present invention, specific embodiments of the present invention will now be described.
Example 1
A preparation method of a composite solid acid catalyst comprises the following steps:
1. preparing mixed powder: mixing bentonite, zeolite powder and boron nitride according to a mass ratio of 6:1, ball milling after uniformly mixing, and controlling the ball-material ratio in the ball milling process to be 30: 1, the rotating speed is 500rpm, the ball milling time is 3h, and mixed powder is obtained after the ball milling is finished.
2. Preparing microspheres: uniformly mixing the mixed powder, citric acid, acetic acid and chitin to obtain a primary mixed solution, controlling the temperature of the primary mixed solution to 50 ℃, then slowly dropwise adding a cross-linking solution into the primary mixed solution while performing ultrasonic oscillation, controlling the frequency of the ultrasonic oscillation to be 20kHz, the dropwise adding time to be 30min, continuing the ultrasonic oscillation for 20min after the dropwise adding is finished to obtain a mixed solution, performing spray drying on the mixed solution, controlling the temperature of an air inlet to be 110 ℃, the temperature of an air outlet to be 70 ℃ in the spray drying process, and finishing the spray drying to obtain the microspheres.
Wherein the mass ratio of the mixed powder, the citric acid, the acetic acid and the chitin is 25: 10: 15: 3.
wherein the mass ratio of the primary mixed solution to the cross-linking solution is 1: 1.5.
the cross-linking liquid comprises the following components in parts by weight: 30 parts of diethyl ether, 15 parts of glutaraldehyde, 5 parts of zwitterionic polyacrylamide and 1 part of ethyl acrylate.
3. Preparing solid-carried acid solution: adding nano activated carbon, aluminum chloride, polyvinyl alcohol 1788 and nano alumina into 1.5 mass percent of phosphotungstic acid aqueous solution, and then stirring at the temperature of 50 ℃ and the stirring speed of 200rpm for 2-2.5h to obtain the immobilized acid solution.
Wherein, phosphotungstic acid aqueous solution, nano activated carbon, aluminum chloride and polyvinyl alcohol 1788, the mass ratio of nano alumina is 30: 10: 3: 7: 15.
the particle size of the nano activated carbon is 80 nm.
The particle size of the nano alumina is 50 nm.
4. Preparing a coating microsphere: carrying out solid-carried acid solution and microspheres according to a mass ratio of 2: 1, uniformly mixing, performing microwave oscillation, controlling the intensity of the microwave oscillation to be 50W, controlling the time of the microwave oscillation to be 30min, performing high-pressure treatment after the microwave oscillation is finished, controlling the temperature of the high-pressure treatment to be 65 ℃, the pressure of the high-pressure treatment to be 80MPa, controlling the time of the high-pressure treatment to be 10min, obtaining a wrapping liquid after the high-pressure treatment is finished, then performing vacuum spray drying on the wrapping liquid, controlling the vacuum degree in the vacuum spray drying process to be 0.01MPa, the air inlet temperature to be 110 ℃, the air outlet temperature to be 60 ℃, and obtaining the wrapping microspheres after the vacuum spray drying is finished.
5. Secondary packaging: coating the microspheres and the acid gel according to a mass ratio of 1: 3, uniformly mixing, freezing, spraying and drying, controlling the temperature of a spray freezing air inlet of the freezing spray drying to be-20 ℃, the temperature of an air outlet of the freezing spray drying to be-30 ℃, the temperature of a cold trap to be-60 ℃, and the spraying pressure to be 20bar, and obtaining the composite solid acid catalyst after the freezing spray drying is finished.
The acidic gel comprises the following components in parts by weight: 30 parts of deionized water, 10 parts of hyaluronic acid, 7 parts of alginic acid, 3 parts of xanthan gum, 2 parts of acetic acid and 1 part of poly (diallyldimethylammonium chloride).
The molecular weight of the hyaluronic acid is 1000 kDa.
Example 2
A preparation method of a composite solid acid catalyst comprises the following steps:
1. preparing mixed powder: mixing bentonite, zeolite powder and boron nitride according to a mass ratio of 5: 1, ball milling after uniformly mixing, and controlling the ball-material ratio in the ball milling process to be 25: 1, the rotating speed is 450rpm, the ball milling time is 3.5h, and mixed powder is obtained after the ball milling is finished.
2. Preparing microspheres: uniformly mixing the mixed powder, citric acid, acetic acid and chitin to obtain a primary mixed solution, controlling the temperature of the primary mixed solution to 55 ℃, then slowly dropwise adding a cross-linking solution into the primary mixed solution while performing ultrasonic oscillation, controlling the frequency of the ultrasonic oscillation to be 25kHz, the dropwise adding time to be 35min, continuing the ultrasonic oscillation for 25min after the dropwise adding is finished to obtain a mixed solution, performing spray drying on the mixed solution, controlling the temperature of an air inlet to be 115 ℃ and the temperature of an air outlet to be 75 ℃ in the spray drying process, and finishing the spray drying to obtain the microspheres.
Wherein the mass ratio of the mixed powder, the citric acid, the acetic acid and the chitin is 27: 12: 17: 4.
wherein the mass ratio of the primary mixed solution to the cross-linking solution is 1: 1.7.
the cross-linking liquid comprises the following components in parts by weight: 32 parts of diethyl ether, 17 parts of glutaraldehyde, 7 parts of zwitterionic polyacrylamide and 1.5 parts of ethyl acrylate.
3. Preparing solid-carried acid solution: adding nano activated carbon, aluminum chloride, polyvinyl alcohol 1788 and nano alumina into 1.7 mass percent of phosphotungstic acid aqueous solution, and then stirring at 55 ℃ and a stirring speed of 220rpm for 2.2 hours to obtain the solid-carried acid solution.
Wherein, phosphotungstic acid aqueous solution, nano activated carbon, aluminum chloride and polyvinyl alcohol 1788, the mass ratio of nano alumina is 32: 12: 4: 9: 17.
the particle size of the nano activated carbon is 90 nm.
The particle size of the nano alumina is 70 nm.
4. Preparing a coating microsphere: carrying out solid-carried acid solution and microspheres according to the mass ratio of 2.5: 1, uniformly mixing, performing microwave oscillation, controlling the intensity of the microwave oscillation to be 60W, controlling the time of the microwave oscillation to be 35min, performing high-pressure treatment after the microwave oscillation is finished, controlling the temperature of the high-pressure treatment to be 67 ℃, the pressure of the high-pressure treatment to be 90MPa, controlling the time of the high-pressure treatment to be 12min, obtaining a wrapping liquid after the high-pressure treatment is finished, then performing vacuum spray drying on the wrapping liquid, controlling the vacuum degree in the vacuum spray drying process to be 0.01MPa, the air inlet temperature to be 115 ℃, the air outlet temperature to be 65 ℃, and obtaining the wrapping microspheres after the vacuum spray drying is finished.
5. Secondary packaging: coating the microspheres and the acid gel according to a mass ratio of 1: 3.5, after uniformly mixing, carrying out freeze spray drying, controlling the temperature of a spray freezing air inlet of the freeze spray drying to be-15 ℃, the temperature of an air outlet to be-25 ℃, the temperature of a cold trap to be-55 ℃, and the spray pressure to be 25bar, and finally obtaining the composite solid acid catalyst after the freeze spray drying.
The acidic gel comprises the following components in parts by weight: 32 parts of deionized water, 11 parts of hyaluronic acid, 8 parts of alginic acid, 4 parts of xanthan gum, 3 parts of acetic acid and 1.5 parts of poly (diallyldimethylammonium chloride).
The molecular weight of the hyaluronic acid is 2000 kDa.
Example 3
A preparation method of a composite solid acid catalyst comprises the following steps:
1. preparing mixed powder: mixing bentonite, zeolite powder and boron nitride according to a mass ratio of 6:1, ball milling after uniformly mixing, and controlling the ball-material ratio in the ball milling process to be 30: 1, the rotating speed is 500rpm, the ball milling time is 4 hours, and mixed powder is obtained after the ball milling is finished.
2. Preparing microspheres: uniformly mixing the mixed powder, citric acid, acetic acid and chitin to obtain a primary mixed solution, controlling the temperature of the primary mixed solution to 60 ℃, then slowly dropwise adding a cross-linking solution into the primary mixed solution while performing ultrasonic oscillation, controlling the frequency of the ultrasonic oscillation to be 30kHz, the dropwise adding time to be 40min, continuing the ultrasonic oscillation for 30min after the dropwise adding is finished to obtain a mixed solution, performing spray drying on the mixed solution, controlling the temperature of an air inlet to be 120 ℃, the temperature of an air outlet to be 80 ℃ in the spray drying process, and finishing the spray drying to obtain the microspheres.
Wherein the mass ratio of the mixed powder, the citric acid, the acetic acid and the chitin is 30: 15: 20: 5.
wherein the mass ratio of the primary mixed solution to the cross-linking solution is 1: 2.
the cross-linking liquid comprises the following components in parts by weight: 35 parts of diethyl ether, 20 parts of glutaraldehyde, 8 parts of zwitterionic polyacrylamide and 2 parts of ethyl acrylate.
3. Preparing solid-carried acid solution: adding nano activated carbon, aluminum chloride, polyvinyl alcohol 1788 and nano alumina into 2 mass percent phosphotungstic acid aqueous solution, and then stirring at the stirring speed of 250rpm for 2.5 hours at the temperature of 60 ℃ to obtain the solid-carried acid solution.
Wherein, phosphotungstic acid aqueous solution, nano activated carbon, aluminum chloride and polyvinyl alcohol 1788, and the mass ratio of nano alumina is 35: 15: 5: 10: 20.
the particle size of the nano activated carbon is 100 nm.
The particle size of the nano alumina is 80 nm.
4. Preparing a coating microsphere: carrying out solid-carried acid solution and microspheres according to the mass ratio of 3: 1, uniformly mixing, performing microwave oscillation, controlling the intensity of the microwave oscillation to be 70W, controlling the time of the microwave oscillation to be 40min, performing high-pressure treatment after the microwave oscillation is finished, controlling the temperature of the high-pressure treatment to be 70 ℃, the pressure of the high-pressure treatment to be 100MPa, controlling the time of the high-pressure treatment to be 15min, obtaining a wrapping liquid after the high-pressure treatment is finished, then performing vacuum spray drying on the wrapping liquid, controlling the vacuum degree in the vacuum spray drying process to be 0.02MPa, the air inlet temperature to be 120 ℃, the air outlet temperature to be 70 ℃, and obtaining wrapping microspheres after the vacuum spray drying is finished.
5. Secondary packaging: coating the microspheres and the acid gel according to a mass ratio of 1:4, uniformly mixing, freezing, spraying and drying, controlling the temperature of a spray freezing air inlet of the freezing and spraying drying to be-10 ℃, the temperature of an air outlet to be-20 ℃, the temperature of a cold trap to be-50 ℃, the spraying pressure to be 30bar, and obtaining the composite solid acid catalyst after the freezing and spraying drying.
The acidic gel comprises the following components in parts by weight: 35 parts of deionized water, 12 parts of hyaluronic acid, 10 parts of alginic acid, 5 parts of xanthan gum, 4 parts of acetic acid and 2 parts of poly (diallyldimethylammonium chloride).
The molecular weight of the hyaluronic acid is 3000 kDa.
Comparative example 1
The preparation method of the composite solid acid catalyst described in example 1 is adopted, and the difference is that: and in the step 2, replacing ultrasonic oscillation with mechanical oscillation in the step of preparing the microspheres, and controlling the frequency of the mechanical oscillation to be 20 kHz.
Comparative example 2
The preparation method of the composite solid acid catalyst described in example 1 is adopted, and the difference is that: and (4) omitting high-pressure treatment in the step of preparing the coating microspheres, namely obtaining the coating liquid after microwave oscillation is finished.
Comparative example 3
The preparation method of the composite solid acid catalyst described in example 1 is adopted, and the difference is that: the 5 th secondary wrapping step is omitted.
Example 4
Adding 46kg of absolute ethyl alcohol into a reaction kettle, adding 1kg of the compound solid acid catalyst prepared in the embodiment 1, vacuumizing the reaction kettle until the vacuum degree is 60Pa, introducing nitrogen into the reaction kettle, controlling the gas pressure of the introduced nitrogen to be 0.06MPa, controlling the temperature of the reaction kettle to be 40 ℃ and the stirring speed to be 200rpm, then adding 44kg of ethylene oxide, controlling the adding time of the ethylene oxide to be 1h, and continuing to react for 1.5h after the addition is finished to obtain the ethylene glycol ether. The yield of ethylene glycol ethyl ether was 90.4% and the purity was 90.4%.
After the compound solid acid catalyst prepared by the preparation method of the embodiment is reused for 30 times, the yield of the ethylene glycol ethyl ether can still reach 89.1%; after repeated use for 30 times, the mass of the residual composite solid acid catalyst is 0.92kg, and the mass loss is 8%.
Example 5
Adding 50kg of absolute ethyl alcohol into a reaction kettle, adding 1.1kg of the composite solid acid catalyst prepared in the embodiment 2, vacuumizing the reaction kettle until the vacuum degree is 70Pa, introducing nitrogen into the reaction kettle, controlling the gas pressure of the introduced nitrogen to be 0.07MPa, controlling the temperature of the reaction kettle to be 45 ℃ and the stirring speed to be 250rpm, then adding 45kg of ethylene oxide, controlling the adding time of the ethylene oxide to be 1.2h, and continuing to react for 1.7h after the addition is finished to obtain the ethylene glycol ether. The yield of ethylene glycol ethyl ether was 91.5% and the purity was 88.7%.
After the compound solid acid catalyst prepared by the preparation method of the embodiment is reused for 30 times, the yield of the ethylene glycol ethyl ether can still reach 91.1%; after the composite solid acid catalyst is repeatedly used for 30 times, the mass of the residual composite solid acid catalyst is 1.05kg, and the mass loss is 4.6%.
Example 6
Adding 52kg of absolute ethyl alcohol into a reaction kettle, adding 1.2kg of the composite solid acid catalyst prepared in the embodiment 3, vacuumizing the reaction kettle until the vacuum degree is 80Pa, introducing nitrogen into the reaction kettle, controlling the gas pressure of the introduced nitrogen to be 0.08MPa, controlling the temperature of the reaction kettle to be 50 ℃ and the stirring speed to be 300rpm, then adding 47kg of ethylene oxide, controlling the adding time of the ethylene oxide to be 1.5h, and continuing to react for 2h after the addition is finished to obtain the ethylene glycol ether. The yield of ethylene glycol ethyl ether was 89.6% and the purity was 87.2%.
After the compound solid acid catalyst prepared by the preparation method of the embodiment is reused for 30 times, the yield of the ethylene glycol ethyl ether can still reach 88.7%; after repeated use for 30 times, the mass of the residual composite solid acid catalyst is 1.11kg, and the mass loss is 7.5%.
Comparative example 4
Adding 46kg of absolute ethyl alcohol into a reaction kettle, adding 1kg of the composite solid acid catalyst prepared in the comparative example 1, vacuumizing the reaction kettle until the vacuum degree is 60Pa, introducing nitrogen into the reaction kettle, controlling the gas pressure of the introduced nitrogen to be 0.06MPa, controlling the temperature of the reaction kettle to be 40 ℃ and the stirring speed to be 200rpm, then adding 44kg of ethylene oxide, controlling the adding time of the ethylene oxide to be 1h, and continuing to react for 1.5h after the addition is finished to obtain the ethylene glycol ether. The yield of ethylene glycol ethyl ether was 82.4% and the purity was 82.4%.
After the prepared composite solid acid catalyst is reused for 30 times according to the preparation method of the embodiment, the yield of the ethylene glycol ethyl ether is 81.5%; after repeated use for 30 times, the mass of the residual composite solid acid catalyst is 0.9kg, and the mass loss is 10%.
Comparative example 5
Adding 50kg of absolute ethyl alcohol into a reaction kettle, adding 1.1kg of the composite solid acid catalyst prepared in the comparative example 2, vacuumizing the reaction kettle until the vacuum degree is 70Pa, introducing nitrogen into the reaction kettle, controlling the gas pressure of the introduced nitrogen to be 0.07MPa, controlling the temperature of the reaction kettle to be 45 ℃ and the stirring speed to be 250rpm, then adding 45kg of ethylene oxide, controlling the adding time of the ethylene oxide to be 1.2h, and continuing to react for 1.7h after the addition is finished to obtain the ethylene glycol ether. The yield of ethylene glycol ethyl ether was 86.4% and the purity was 83.7%.
After the prepared composite solid acid catalyst is reused for 30 times according to the preparation method of the embodiment, the yield of the ethylene glycol ethyl ether is 50.7%; after repeated use for 30 times, the mass of the residual composite solid acid catalyst is 0.56kg, and the mass loss is 49.1%.
Comparative example 6
Adding 52kg of absolute ethyl alcohol into a reaction kettle, adding 1.2kg of the composite solid acid catalyst prepared in the comparative example 3, vacuumizing the reaction kettle until the vacuum degree is 80Pa, introducing nitrogen into the reaction kettle, controlling the gas pressure of the introduced nitrogen to be 0.08MPa, controlling the temperature of the reaction kettle to be 50 ℃ and the stirring speed to be 300rpm, then adding 47kg of ethylene oxide, controlling the adding time of the ethylene oxide to be 1.5h, and continuing to react for 2h after the addition is finished to obtain the ethylene glycol ether. The yield of ethylene glycol ethyl ether was 76.9% and the purity was 74.8%.
After the prepared composite solid acid catalyst is reused for 30 times according to the preparation method of the embodiment, the yield of the ethylene glycol ethyl ether is 45.2%; after the composite solid acid catalyst is repeatedly used for 30 times, the mass of the residual composite solid acid catalyst is 0.46kg, and the mass loss is 61.7%.
All percentages used in the present invention are mass percentages unless otherwise indicated.
Finally, it should be noted that: although the present invention has been described in detail with reference to the foregoing embodiments, it will be apparent to those skilled in the art that changes may be made in the embodiments and/or equivalents thereof without departing from the spirit and scope of the invention. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.