CN106423047B - Spherical normal alkane adsorbent and preparation method thereof - Google Patents
Spherical normal alkane adsorbent and preparation method thereof Download PDFInfo
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Abstract
The spherical normal alkane adsorbent comprises 96-100 mass% of a 5A molecular sieve and 0-4 mass% of a binder or a matrix, wherein the burning bulk density of the adsorbent is 0.72-0.80 g/mL, the burning reduction amount at 600 ℃ is less than 3 mass%, and the compression-resistant crushing rate of a 250N thimble is less than 6%. The adsorbent has the advantages of low binder content, high adsorption capacity, good strength, high bulk density, and simple preparation method.
Description
Technical Field
The invention relates to a hydrocarbon adsorbent and a preparation method thereof, in particular to a normal alkane adsorbent and a preparation method thereof.
Background
The separation of normal paraffins from various petroleum products has important practical and economic values, for example, the separation of normal paraffins from gasoline fractions can significantly improve the octane number of gasoline; nC separated from kerosene fraction10～nC14The normal alkane is a raw material for preparing the detergent; nC separated from diesel oil fraction14 +The normal paraffin can be used for synthesizing high value-added products such as petroleum protein, chlorinated paraffin, plasticizer, lubricating oil additive and the like; the separation of normal paraffins and other hydrocarbons (isoparaffins, naphthenes, and aromatics) in naphtha allows for optimization of the feedstock and increases the downstream ethylene and reformer efficiencies. The petroleum product has a wide distillation range and small boiling point difference among isomers, and is difficult to separate normal paraffin by a rectification method. The effective aperture of the 5A molecular sieve is 0.50nm, and the molecular sieve can adsorb straight-chain normal alkane, prevent branched isoparaffin, cyclane and arene from entering pores, and realize adsorption separation of normal alkane.
The synthesized molecular sieve is usually fine powder, and can meet industrial application only after a certain amount of binder is added for agglomeration and molding. Wherein, the kaolin clay is a relatively common adhesive for molecular sieve molding, and has the advantages of low price, strong viscosity and the like. For preparing molecular sieve adsorbents, the addition of clay can make molecular sieves into various shapes and greatly improve the strength of molecular sieve formed bodies, but because the clay does not usually have adsorption selectivity, the addition of clay can reduce the effective adsorption capacity of the adsorbent per unit mass or unit volume, more adsorbents need to be filled in order to ensure the adsorption and separation treatment capacity, and the sizes of adsorption containers and accessories are increased, so that the investment cost of the device is increased. The clay can also block the molecular sieve pore channels, affecting the adsorption and desorption speed. Impurities in the clay can also adversely affect adsorptive separation. The clay and molecular sieve formed body are roasted and alkali treated to convert the clay into molecular sieve and raise the adsorption capacity and strength of the formed body greatly.
USP4818508 discloses a method for synthesizing A-type molecular sieve from kaolin with particle size of 1.5-15 μm, which comprises adding a small amount of pore-forming agent, adding water, mixing, molding, calcining at high temperature, hydrothermally treating with alkaline solution to convert kaolin into 4A molecular sieve, and adding alumina for aluminum supplement during alkaline solution treatment. The 4A molecular sieve adsorbent prepared by the patent by taking kaolin as a raw material has greatly reduced cost, but the content of the prepared adsorbent molecular sieve can only reach about 94% at most under the influence of kaolin conversion rate.
CN92111878.3 discloses a method for preparing a 5A adsorbent without an adhesive, which comprises the steps of adding 15-35% of kaolin clay and 0.2-2% of sesbania powder, sodium cellulose or other starch into a 4A molecular sieve during or after synthesis of the molecular sieve, forming, treating by a sodium hydroxide solution and carrying out ion exchange by calcium chloride. In order to ensure the requirements of the adsorbent on formation and strength, the kaolin has large addition amount, but 100 percent of the kaolin is difficult to be converted into the molecular sieve, and the performance of the molecular sieve raw powder is difficult to be achieved after the kaolin is subjected to crystal conversion.
CN03115743.2 discloses a preparation method of a 5A molecular sieve for pressure swing adsorption and petroleum dewaxing, which comprises the steps of mixing 80-95 parts by weight of 4A molecular sieve raw powder with 5-20 parts by weight of kaolin clay, adding 1-50 parts by weight of additive plant fiber, and granulating in a high-speed granulator. And then screening the granulated intermediate product according to the fineness requirement of the product, and roasting at a high temperature of 200-1000 ℃ after drying. Immersing the intermediate product after roasting into 4-25 wt% sodium hydroxide solution for alkali treatment, washing, and then using 2-20 wt% CaCl2Solution of Ca2+Exchanging, washing and drying, and then carrying out secondary roasting on the granular product at 100-800 ℃ to obtain a 5A molecular sieve product. This patent uses the shaping of high-speed granulator, has reduced binder content, has improved the effective adsorption capacity of adsorbent, uses plant fiber powder, has improved the pore structure of adsorbent, has improved the diffusion rate of product.
Disclosure of Invention
The invention aims to provide a spherical normal alkane adsorbent and a preparation method thereof, wherein the adsorbent is low in binder content, high in adsorption capacity, good in strength, large in bulk density, and simple and feasible in preparation method.
The spherical normal alkane adsorbent provided by the invention comprises 96-100 mass% of a 5A molecular sieve and 0-4 mass% of a binder or a matrix, wherein the burning bulk density of the adsorbent is 0.72-0.80 g/mL, the burning reduction at 600 ℃ is less than 3 mass%, and the compression-resistant breakage rate of a 250N thimble is less than 6%.
The invention adopts a tabletting and re-crushing method to prepare the adsorbent, and the used binder has smaller grain diameter, and the prepared adsorbent has good strength and large bulk density.
Detailed Description
The invention mixes the raw material of the adsorbent, NaA molecular sieve, the adhesive and the auxiliary agent, then carries on tabletting and forming under high pressure, then breaks the tablet into particles smaller than 0.27mm, uses the particles as the particles to carry on ball mixing and forming, which is good for the rapid growth of the small balls, the obtained small balls are baked at high temperature, the adhesive is transformed into the crystallizable substance, then uses the alkali solution to process, the adhesive is transformed into NaA molecular sieve, then carries on Ca2+And exchanging to prepare the spherical adsorbent containing the 5A molecular sieve. Compared with the method of directly using loose material rolling balls, the method of the invention improves the bulk density and crushing strength of the product and increases the adsorption capacity of the adsorbent.
The binder of the adsorbent is preferably kaolin or residue-matrix after kaolin crystal transformation, the content of the 5A molecular sieve in the adsorbent is preferably 97-100 mass%, also can be 97-99.5 mass%, and the content of the matrix can be 0.5-3 mass%.
The burning base bulk density of the adsorbent is preferably 0.74-0.80 g/mL, the burning reduction amount at 600 ℃ is preferably less than 2.3 mass%, and the compression-resistant breakage rate of a 250N thimble is preferably less than 5%.
The preparation method of the adsorbent provided by the invention comprises the following steps:
(1) mixing raw powder of a NaA molecular sieve and a binder according to the weight ratio of 90-97: 3-10, adding an auxiliary agent accounting for 1-10% of the mass of the mixture, uniformly mixing, tabletting and forming, crushing the flaky material into particles smaller than 0.27mm, wherein the binder is kaolin, dickite, perlite or halloysite,
(2) forming the ball of the granules crushed in the step (1), adding water into the materials in a spraying mode in the ball rolling process, adding mixed powder of molecular sieve raw powder, a binder and an auxiliary agent into the materials in a throwing mode to form fine granules into small balls, collecting the small balls with the granularity of 0.3-0.8 mm,
(3) drying and roasting the pellets obtained in the step (2), treating the pellets with NaOH aqueous solution at 85-100 ℃ to convert the binder into the A-type molecular sieve, and then using Ca-containing solution2+Is ion exchanged and then activated.
In the method (1), the raw material mixture tablet is prepared, and in order to reduce the dosage of the binder, the particle size of the binder is preferably 0.3-2.0 mu m. Because the particle size is small, more contact points exist between clay particles of unit mass and NaA molecular sieve crystal grains, and in addition, because the particle size of the clay is small, the alkali treatment in-situ crystal transformation speed of the clay is obviously accelerated, and the crystal transformation rate is improved. (1) In the steps, raw materials for preparing the adsorbent are mixed, then the mixture is pressed into a sheet-shaped agent under the pressure of 300-600 MPa, and then the sheet-shaped agent is crushed into fine particles with the particle size of less than 0.27 mm. The binder is preferably kaolinite or halloysite. The auxiliary agent is preferably one or more of lignin, sesbania powder, dry starch, carboxymethyl cellulose and activated carbon.
The method (2) comprises the steps of rolling ball forming by using particles crushed after tabletting as seeds, wherein the rolling ball can be carried out in a high-speed granulator, a sugar coating machine, a disc granulator or other rolling ball equipment, water is added into the materials in a spraying mode to ensure that the water content in the materials is 40-47% by mass, a mixture of molecular sieve raw powder, a binder and an auxiliary agent is added into the materials in a throwing mode to ensure that fine particles grow and become round to form small balls, and the small balls with the particle size of 0.3-0.8 mm are obtained through screening.
(3) The rolled pellets are subjected to in-situ crystal transformation, the pellets are dried at the preferred drying temperature of 80-200 ℃ for 1-10 h, and then are roasted at the temperature of 500-700 ℃ for 2-8 h, so that the binder in the pellets is activated. And treating the activated pellets with NaOH aqueous solution for in-situ crystal transformation to convert the activated binder into A-type zeolite, wherein the concentration of the NaOH aqueous solution is preferably 1-4 mol/L, the treatment temperature is preferably 85-100 ℃, and the time is preferably 1-4 h. Washing the alkali-treated pellets by deionized water until the pH is less than 10, and then drying at 80-120 ℃ for preferably 2-8 h.
(3) In the step, the dried pellets after in-situ crystal transformation are added with CaCl2Or Ca (NO)3)2Formulated Ca-containing2+Is impregnated with an aqueous solution of (a) to perform ion exchange. The Ca is contained2+Ca in the aqueous solution of (2)2+The concentration of (b) is preferably 0.5-2.0 mol/L, and the ion exchange temperature is 85-100 ℃. Ca in the adsorbent after ion exchange2+The exchange degree of the spherical molecular sieve adsorbent reaches 67-100%, and then the spherical molecular sieve adsorbent is activated until the water content is reached, namely the ignition reduction is less than 3 mass%, so that the spherical molecular sieve adsorbent is obtained. The activation temperature is 300-500 ℃.
In the adsorption separation operation, the adsorption strength and the desorption rate are important indexes for measuring the performance of an adsorption separation system (including an adsorbent and a desorbent). The method of the invention uses a dynamic pulse experimental method to determine the influence of using different desorbents and adsorbents on the adsorption strength and the desorption rate.
The pulse experimental device comprises a feeding system, a nitrogen system, an adsorption column, an electric heating furnace, a pressure control valve, a micro plunger pump and the like. The adsorption column is a stainless steel coil pipe with the diameter of 8mm multiplied by 1mm and the length of 1800mm, the loading of the adsorbent is 50mL, and the adsorption column is placed in a vertical electric furnace with automatic temperature control for heating. The lower inlet of the adsorption column is connected with a feeding system and a nitrogen system, and the upper outlet is connected with a pressure control valve and then connected with an effluent collector.
The raw materials used in the experiment are pulse liquid and desorption liquid which are prepared according to a certain proportion, and the pulse liquid is used for taking certain non-adsorption components and adsorption components in naphtha raw materialDiluting isooctane to obtain the product; the desorption liquid consists of a desorption agent and isooctane, and the isooctane is a diluent. Dehydrating and activating the adsorbent at 500 deg.C, controlling water content to below 2.0 wt%, and filling into an adsorption column. Introducing nitrogen to displace oxygen in the system, removing gas in the system by desorption liquid, increasing the pressure to 1.2MPa, starting an electric heating furnace to increase the temperature to the required temperature, stopping introducing the desorption liquid when the composition of materials at an inlet and an outlet is consistent, injecting pulse liquid with a certain volume, eluting by the desorption liquid, taking about 0.1mL of desorption sample at the outlet of an adsorption column every 2min until all normal alkanes in the pulse liquid are completely desorbed. Analyzing the composition of the sample by gas chromatography, and drawing a mass fraction change curve of each component by taking the feeding volume of desorption liquid as a horizontal coordinate and the peak area percentage of each component of the effluent liquid as a vertical coordinate during elution. The non-adsorbed component (excluding diluent) in the pulse liquid first comes to the first peak, the midpoint of the half-peak width is taken as the zero point, and the volume difference from the midpoint of the half-peak width to the zero point of each adsorbed component curve is called the net retention volume delta V of the componentRA larger value indicates a stronger adsorption capacity for the adsorbed component. The mutual replacement speed between the desorption agent and the adsorption components in the raw material can be determined by the half-peak width W of the mass fraction curve of each adsorption component1/2The smaller the value of the half-peak width is, the faster the mass transfer speed is, and the faster the replacement speed between the desorption agent and the adsorption component in the raw material is. The smaller half-peak width can also reduce the overlapping degree of concentration change curves of the adsorption component and the non-adsorption component in the raw material, thereby achieving better separation effect. For an adsorption separation device applied in industry, on the premise of meeting the separation effect, the desorption agent is expected to have higher desorption speed on the adsorbed components in the raw materials, so that the consumption of the desorption agent can be reduced, and the energy consumption is saved.
The present invention is further illustrated by the following examples, but the present invention is not limited thereto.
In the following examples and comparative examples, the method for measuring the amount of methanol adsorbed by the adsorbent sample was: taking 1g of sample, activating at 500 ℃ for 2h, cooling to 25 ℃ in a dryer, and taking the net weight of the sample as M0Saturating the sample with mixed gas of nitrogen and methanol at 35 deg.C, mixingThe total pressure of the gas is 0.1MPa, wherein the partial pressure of the methanol is 0.5 times of the saturated vapor pressure of the methanol at the temperature, and the net weight of the sample after adsorption saturation is M1When the amount of toluene adsorbed in the sample (mg/g) is 1000 × (M)1-M0)/M0。
The mechanical strength of the adsorbent is characterized by the compression-resistant breakage rate of the small balls, and the determination method comprises the following steps: taking a proper amount of adsorbent with constant weight in air, weighing, and then putting into a stainless steel cylinder with a sealed bottom end, wherein the cross-sectional area of the stainless steel cylinder is 6.28cm2The cylindrical thimble matched with the stainless steel cylinder is arranged above the adsorbent, then the adsorbent is placed on a particle strength tester to pressurize the thimble to 250N, the pressure is relieved, the adsorbent is taken out, the adsorbent is screened by a 0.3 mm mesh screen, the small balls which do not pass through the mesh are weighed, the mass percentage of the reduced mass to the mass of the sample before pressurization is the compression-resistant crushing rate of the tested sample, and the lower the crushing rate is, the better the strength of the sample is.
The detection method of the ignition-based bulk density of the adsorbent comprises the following steps: taking a proper amount of adsorbent with constant weight in air, loading into a glass measuring cylinder, placing on a tap density instrument, vibrating for 5min, and reading volume number V, wherein the amplitude is 3mm, and the vibration frequency is 290 times/min. Then, the net weight M of the sample is weighed, and then an appropriate amount of the sample is taken to test the ignition loss K (%) of the mass baked at 600 ℃ for 2 hours, so that the ignition-based bulk density (g/mL) of the adsorbent is M x (1-K)/V.
The NaA molecular sieve powder used in the examples and comparative examples had a methanol adsorption amount of 190mg/g and a crystal grain size of 0.5 to 1.5 μm, and was manufactured by the Chinese petrochemical catalyst, Zilu division. The mass of the NaA molecular sieve and the kaolin used in the examples are both referred to as the ignition base mass, and the ignition reduction test condition is 600 ℃ for 2 h.
The Ca exchange of the 5A sorbent samples was calculated as follows: analysis of Na in sample by X-ray fluorescence spectrometry (XRF)2The mass percentages of O and CaO are respectively recorded as MNAnd MCDegree of Ca exchange ═ MC/MCaO/(MC/MCaO+MN/MNa2O)，MCaOAnd MNa2OAre respectively CaO and Na2Molar mass of O.
Example 1
(1) Preparing pellets
60kg of NaA molecular sieve powder, 2kg of kaolin with the particle size of 0.3-1.0 mu m and 1kg of sesbania powder are uniformly mixed to prepare mixed powder, a rotary tablet machine is used for preparing the mixed powder into a tablet shape under the pressure of 300MPa, the tablet shape agent is crushed and screened, particles with the particle size of less than 0.27mm are put into a rotary high-speed granulator for rolling, deionized water is sprayed into the materials and the mixed powder is thrown in the process of rolling, the water content of the materials is kept at 45 mass percent, and small balls with the diameter of 0.3-0.8 mm are screened after 1 hour.
(2) In situ crystallization
Drying 50L of the pellets at 80 ℃ for 8h, roasting at 550 ℃ for 4h, soaking in 100L of 1.5mol/L NaOH aqueous solution at 91 ℃ for 1h to crystallize the kaolin in situ, washing with deionized water until the pH of a washing solution is less than 10, and drying at 100 ℃ to obtain crystallized NaA pellets.
(3) Preparation of spherical 5A molecular sieve adsorbent
Soaking 50L of crystallized NaA pellets in 200L of 1.3mol/L CaCl2Ca in aqueous solution at 95 ℃2+Exchanging for 4h, then washing with deionized water, drying at 100 ℃ for 4h, and activating at 400 ℃ for 3h to obtain the 5A molecular sieve spherical adsorbent A-1, wherein the content of the A-type molecular sieve is 100 mass%, and the physical properties are shown in Table 1.
Example 2
60kg of NaA molecular sieve raw powder, 4kg of kaolin with the particle size of 1.0-1.3 mu m and 1kg of sesbania powder are uniformly mixed to prepare mixed powder, the mixed powder is prepared into tablets according to the method of the step (1) in the example 1, and then the tablets are crushed and rolled, and then small balls with the diameter of 0.3-0.8 mm are screened.
And (3) drying 50L of the pellets at 80 ℃ for 8h, roasting at 580 ℃ for 4h, soaking 100L of 2.0mol/L NaOH aqueous solution at 97 ℃ for 2h to crystallize the kaolin in situ, washing with deionized water until the pH of a washing solution is less than 10, and drying to obtain crystallized NaA pellets.
Taking the NaA pellets after crystal transformation to carry out Ca according to the method of the step 1(3)2+Exchange, except for the CaCl used2The concentration of the aqueous solution is 1.5mol/L, the spherical adsorbent A-2 of the 5A molecular sieve is obtained after being dried and activated for 3h at 350 ℃, wherein the content of the A-type molecular sieve is 100 mass percent,the physical properties are shown in Table 1.
Example 3
60kg of NaA molecular sieve raw powder, 2kg of kaolin with the particle size of 0.3-1.0 mu m and 1kg of sesbania powder are uniformly mixed to prepare mixed powder, tablets are prepared according to the method of the step 1 and 1, then the tablets are crushed and rolled, and then small balls with the diameter of 0.3-0.8 mm are sieved, except that the pressure during tabletting is 600 MPa.
And (3) drying 50L of the pellets at 80 ℃ for 8h, roasting at 600 ℃ for 4h, soaking in 100L of 1.5mol/L NaOH aqueous solution at 93 ℃ for 1h to crystallize the kaolin in situ, washing with deionized water until the pH of a washing solution is less than 10, and drying to obtain crystallized NaA pellets.
Taking the NaA pellets after crystal transformation to carry out Ca according to the method of the step 1(3)2+Exchange, except for the CaCl used2The concentration of the aqueous solution is 2.0mol/L, and the spherical adsorbent A-3 of the 5A molecular sieve is obtained after being dried and activated for 3h at 450 ℃, wherein the content of the A-type molecular sieve is 100 mass percent, and the physical properties are shown in Table 1.
Example 4
60kg of NaA molecular sieve raw powder, 6kg of kaolin with the particle size of 1.0-1.3 mu m and 3kg of sesbania powder are uniformly mixed to prepare mixed powder, tablets are prepared according to the method of the step 1 and 1, then the tablets are crushed and rolled, and then small balls with the diameter of 0.3-0.8 mm are sieved, except that the pressure during tabletting is 450 MPa.
And (3) drying 50L of the pellets at 80 ℃ for 8h, roasting at 600 ℃ for 4h, soaking in 150L of 1.0mol/L NaOH aqueous solution at 91 ℃ for 1h to crystallize the kaolin in situ, washing with deionized water until the pH of a washing solution is less than 10, and drying to obtain crystallized NaA pellets.
Taking the NaA pellets after crystal transformation to carry out Ca according to the method of the step 1(3)2+Exchange, except for the CaCl used2The concentration of the aqueous solution is 1.8mol/L, the exchange temperature is 90 ℃, and the spherical adsorbent A-4 of the 5A molecular sieve is obtained by activating for 2h at 500 ℃ after drying, wherein the content of the A-type molecular sieve is 100 mass percent, and the physical properties are shown in Table 1.
Example 5
60kg of NaA molecular sieve raw powder, 4kg of kaolin with the granularity of 0.3-0.8 mu m and 2kg of sesbania powder are uniformly mixed to prepare mixed powder, tablets are prepared according to the method of the step 1 and the step 1, then the tablets are crushed and rolled, and then small balls with the diameter of 0.3-0.8 mm are sieved, except that the pressure during tabletting is 540 MPa.
And (3) drying 50L of the pellets at 80 ℃ for 8h, roasting at 540 ℃ for 4h, soaking in 100L of 1.5mol/L NaOH aqueous solution at 90 ℃ for 1h to crystallize the kaolin in situ, washing with deionized water until the pH of a washing solution is less than 10, and drying to obtain crystallized NaA pellets.
Taking the NaA pellets after crystal transformation to carry out Ca according to the method of the step 1(3)2+Exchange, except for the CaCl used2The concentration of the aqueous solution is 1.6mol/L, the exchange temperature is 90 ℃, the aqueous solution is dried and activated for 3h at 400 ℃ to obtain the 5A molecular sieve spherical adsorbent A-5, wherein the content of the A-type molecular sieve is 99.5 mass percent, and the balance is a matrix formed after the kaolin is crystallized, and the physical properties are shown in Table 1.
Comparative example 1
Uniformly mixing 60kg of NaA molecular sieve raw powder, 12kg of kaolin with the granularity of 10-15 mu m and 2kg of sesbania powder to prepare mixed powder, putting the mixed powder into a rotary high-speed granulator for rolling, spraying deionized water into the material and throwing the mixed powder in the rolling process, keeping the water content of the material at 45 mass percent, sieving the material after 1h to obtain small balls with the diameter of 0.3-0.8 mm, drying the small balls at 120 ℃ for 4h, and roasting the small balls at 550 ℃ for 4 h.
And soaking 50L of the roasted pellets in 100L of NaOH aqueous solution with the concentration of 1.5mol/L at 94 ℃ for 1h to crystallize the kaolin in situ, washing the crystallized pellets with deionized water until the pH value is less than 10, and drying the crystallized pellets at 100 ℃ to obtain the crystallized NaA pellets.
Soaking 50L of crystallized NaA pellets in 200L of 1.3mol/L CaCl2Ca in an aqueous solution of (2)2+Exchanging for 4h, washing with deionized water, drying at 100 ℃ for 4h, and activating at 350 ℃ for 3h to obtain the 5A molecular sieve spherical adsorbent B-1, wherein the content of the A-type molecular sieve is 93.7 mass%, and the balance is a matrix formed after the kaolin is subjected to crystal transformation, and the physical properties are shown in Table 1.
Comparative example 2
Uniformly mixing 60kg of NaA molecular sieve raw powder, 6kg of kaolin with the particle size of 20-30 mu m and 2kg of sesbania powder to prepare mixed powder, pressing and forming by using a rotary tablet press under the pressure of 450MPa, crushing and screening the formed tablets, putting particles smaller than 0.27mm into a rotary high-speed granulator for rolling, spraying deionized water into the materials and throwing the mixed powder in the process of rolling, keeping the water content of the materials at 45 mass%, screening small balls with the diameter of 0.3-0.8 mm after 1 hour, drying at 80 ℃ for 8 hours, and roasting at 600 ℃ for 4 hours.
Soaking 50L of the roasted pellets in 100L of NaOH aqueous solution with the concentration of 1.5mol/L at 95 ℃ for 1h to crystallize the kaolin in situ, washing the crystallized pellets with deionized water until the pH value is less than 10, and drying the crystallized pellets at 100 ℃ to obtain the crystallized NaA pellets.
Soaking 50L of alkali-treated NaA pellets in 200L of 1.5mol/L CaCl2Ca in aqueous solution at 95 ℃2 +Exchanging for 4h, then washing with deionized water, drying at 100 ℃ for 4h, and activating at 500 ℃ for 2h to obtain the 5A molecular sieve spherical adsorbent B-2, wherein the content of the A-type molecular sieve is 96.3 mass%, and the balance is a matrix formed after the kaolin is subjected to crystal transformation, and the physical properties are shown in Table 1.
Comparative example 3
60kg of NaA molecular sieve raw powder, 2kg of kaolin with the particle size of 1.5-2.0 mu m and 1kg of sesbania powder are uniformly mixed to prepare mixed powder, and rolling and subsequent treatment are carried out according to the method of comparative example 1 to obtain the 5A molecular sieve spherical adsorbent B-3, wherein the content of the A-type molecular sieve is 100 mass%, and the physical properties are shown in Table 1.
Example 6
Preparing a pulse liquid and a desorption liquid according to a certain proportion, wherein 2-methylpentane and nC in the pulse liquid10～nC16Each of the n-alkanes having 10 to 16 carbon atoms contained in the oil composition contains 5% by mass of isooctane and the balance of isooctane in an amount of 60% by mass. The desorption solution was 70 mass% nC7(n-heptane) and 30 mass% of isooctane.
Filling the adsorbent into an adsorption column of a pulse test device for compaction, firstly introducing nitrogen to replace oxygen in the system, then removing gas in the system by desorption liquid, raising the pressure to 1.2MPa, wherein the flow rates of the desorption agent and the pulse liquid are both 1.0mL/min, and the column temperature is 180 ℃. The results of the pulse tests carried out according to the method of the invention are shown in Table 2.
TABLE 1
TABLE 2
Claims (8)
1. The spherical normal alkane adsorbent comprises 99.5-100 mass% of a 5A molecular sieve and 0-0.5 mass% of a binder or a matrix, wherein the burning bulk density of the adsorbent, measured by roasting the adsorbent at 600 ℃ for 2 hours, is 0.74-0.80 g/mL, the burning reduction is less than 2.3 mass%, and the compressive breakage rate of a 250N thimble is less than 6%.
2. The sorbent according to claim 1, characterized in that the binder is kaolin or a residue of kaolin after the transcrystallization.
3. A method of making the adsorbent of claim 1, comprising the steps of:
(1) mixing raw powder of a NaA molecular sieve and a binder according to the weight ratio of 90-97: 3-10, adding an auxiliary agent accounting for 1-10% of the mass of the mixed material, uniformly mixing, tabletting and forming under the pressure of 300-600 MPa, crushing the flaky material into particles smaller than 0.27mm, wherein the binder is kaolin, dickite, perlite or halloysite, the particle size of the binder is 0.3-2.0 mu m,
(2) forming the ball of the granules crushed in the step (1), adding water into the materials in a spraying mode in the ball rolling process, adding mixed powder of molecular sieve raw powder and a binder into the materials in a throwing mode to form small balls of fine granules, collecting the small balls with the granularity of 0.3-0.8 mm, spraying water into the powder in the ball rolling process to ensure that the water content in the materials is 40-47 mass%,
(3) drying and roasting the pellets obtained in the step (2), treating the pellets with NaOH aqueous solution at 85-100 ℃ to convert the binder into the A-type molecular sieve, and then using Ca-containing solution2+Is ion exchanged and then activated.
4. The method according to claim 3, wherein the auxiliary agent is one or more selected from lignin, sesbania powder, dry starch, carboxymethyl cellulose and activated carbon.
5. The method according to claim 3, wherein the concentration of the NaOH aqueous solution in the step (3) is 1-4 mol/L, the soaking temperature is 85-100 ℃, and the soaking time is 1-4 h.
6. The method according to claim 3, wherein step (3) comprises using CaCl2Or Ca (NO)3)2Preparation of Ca2+An aqueous solution of (a).
7. The method according to claim 3, wherein the Ca content in the step (3)2+Ca in the aqueous solution of (2)2+The concentration of (A) is 0.5-2.0 mol/L, and the ion exchange temperature is 85-100 ℃.
8. The method according to claim 3, wherein Ca is carried out in step (3)2+The temperature of activation after exchange is 300-500 ℃.
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| CN114433012B (en) * | 2020-11-06 | 2023-06-02 | 中国石油化工股份有限公司 | Forming method of molecular sieve adsorbent, molecular sieve adsorbent prepared by forming method and application of molecular sieve adsorbent |
| CN114682234B (en) * | 2020-12-31 | 2023-07-28 | 中国石油化工股份有限公司 | Preparation method of pressure swing adsorption molecular sieve adsorbent |
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