Aromatization catalyst, preparation method, regeneration method thereof, and aromatization method

Abstract

The present disclosure provides an aromatization catalyst, a preparation method, a regeneration method and an aromatization method thereof. The preparation method comprises steps of: mixing a zeolite molecular sieve with a binder to obtain a catalyst precursor; the catalyst precursor is successively subjected to an ion exchange modification and a first modification treatment, and then subjected to a hydrothermal treatment, and further subjected to active metal loading and a second modification treatment, to obtain the aromatization catalyst. The aromatization catalyst has good carbon deposition resistance and high aromatization activity, and enables an aromatization reaction to be completed under mild conditions, and has high aromatic selectivity, and the liquid yield is above 98.5%.

Claims

1. A preparation method for an aromatization catalyst, consisting of steps of: mixing a nano zeolite molecular sieve with a binder at a dry basis weight ratio of (1:9)˜(9:1) to obtain a catalyst precursor; the catalyst precursor is successively subjected to an ion exchange modification and a first modification treatment, then subjected to a hydrothermal treatment, and further subjected to active metal loading and a second modification treatment, to obtain the aromatization catalyst; wherein an exchange element used for the ion exchange modification is at least one alkali metal selected from Group IA of the Periodic Table of the Elements, with a loading amount of 0.1˜2 wt % based on a weight of the exchange element with respect to a weight of the catalyst precursor; a first modifying element used in the first modification treatment is at least one element selected from Group IA, Group VA, and lanthanide metals of the Periodic Table of the Elements, with a loading amount of 0.05˜10 wt % based on a weight of the first modifying element with respect to the weight of the catalyst precursor; the active metal is at least one element selected from Group VIIB, Group VIII, Group IB and Group IIB of the Periodic Table of the Elements, with a loading amount of 0.5˜25 wt % based on a weight of the active metal with respect to the weight of the catalyst precursor; a second modifying element used for the second modification treatment is at least one element selected from Group VA and the lanthanide metals of the Periodic Table of Elements, with a loading amount of 0.05˜10 wt % based on a weight of the second modifying element with respect to the weight of the catalyst precursor.

2. The preparation method according to claim 1, wherein using a salt solution or an alkali solution containing sodium ions and/or potassium ions as an ion exchange solution to perform the ion exchange modification on the catalyst precursor, controlling the ion exchange modification is conducted at 60˜120° C. for at least 30 minutes to obtain a treated catalyst precursor, then drying the treated catalyst precursor at 60˜280° C. for at least 3 hours, and finally calcining the treated catalyst precursor at 450˜700° C. for at least 1 hour.

3. The preparation method according to claim 1, wherein dissolving a metal salt of the active metal with 0.1˜1.0 mol/L citric acid aqueous solution to prepare an impregnation liquid, and impregnating the catalyst precursor with the impregnation liquid to obtain an impregnated catalyst precursor, then drying and calcining the impregnated catalyst precursor so as to achieve the active metal loading; wherein, a mass ratio of the impregnation liquid to the catalyst precursor is (0.8˜3.0): 1, the drying is performed at a temperature of 50˜180° C. for no less than 2 hours; the calcination is performed at a temperature of 100˜650° C. for no less than 2 hours.

4. The preparation method according to claim 1, wherein performing the hydrothermal treatment under a water vapor atmosphere performing at a temperature of 300˜600° C. for at least 1 hour.

5. The preparation method according to claim 1, wherein sum of loading amounts of the first modifying element and the second modifying element is 0.5˜8.0 wt % based on the weight of the catalyst precursor.

Description

DESCRIPTION OF EMBODIMENTS

(1) To make the objectives, technical solutions, and advantages of embodiments of the present disclosure clearer, the following clearly and comprehensively describes the technical solutions in embodiments of the present disclosure. Apparently, the described embodiments are merely a part rather than all embodiments of the present disclosure.

Example 1

(2) This embodiment provides a method for preparing an aromatization catalyst, comprising the following steps of:

(3) 1. a nano-scale HZSM-5 molecular sieve with Si/Al ratio of 25 was physically mixed with pseudoboehmite at a ratio of 4:1 at room temperature to obtain a catalyst precursor.

(4) 2. an ion exchange modification of the catalyst precursor was performed by a method of constant temperature water bath, in particular, sodium hydroxide is dissolved in deionized water and mixed with the catalyst precursor to obtain a mixture, and then placing the mixture in a 90° C. water bath and stirring for 2 hours, so that the loading amount of sodium is about 0.2 wt %, a treated catalyst precursor is obtained, and then drying the treated catalyst precursor at about 120° C. for about 8 hours and calcining the treated catalyst precursor at about 540° C. for about 4 hours.

(5) 3. a first modification treatment of the catalyst precursor after the ion exchange modification is carried out by an equal volume impregnation method, in particular, dissolving ammonium dihydrogen phosphate in deionized water, and then impregnating the catalyst precursor, controlling a mass ratio of an aqueous solution of ammonium dihydrogen phosphate to the catalyst precursor to be (1.0±0.2):1, so that the loading amount of phosphorus is about 1 wt %; after the impregnation was completed, aging the resulting catalyst precursor at about 20° C. for about 6 hours, drying the catalyst precursor at about 120° C. for about 8 hours, and calcining the catalyst precursor at about 540° C. for about 4 hours.

(6) 4. a hydrothermally treatment of the catalyst precursor after the first modification treatment is conducted at a temperature of about 300° C. in a 100% steam atmosphere for about 6 hours. And then active metal loading of the hydrothermally treated catalyst precursor is carried out by an equal volume impregnation method, dissolving zinc nitrate in a 0.1 mol/L citric acid solution to obtain an impregnation liquid, and controlling a mass ratio of the impregnation liquid to the catalyst precursor after the hydrothermally treatment to be (1.0±0.2): 1, an impregnation temperature to be about 20° C., and an impregnation time to be about 10 hours, so that the loading amount of zinc is about 5 wt %; after the impregnation was completed, then aging the impregnated catalyst precursor at about 25° C. for about 4 hours, drying the impregnated catalyst precursor at about 120° C. for about 10 hours in an air atmosphere, and calcining the impregnated catalyst precursor at 540° C. for about 4 hours.

(7) 5. a second modification treatment of the active metal loaded catalyst precursor is carried out by the equal volume impregnation method so as to obtain the aromatization catalyst, referring to step 3 for detailed procedures, and the obtained aromatization catalyst was referred to as catalyst A.

Example 2

(8) This embodiment provides a method for preparing an aromatization catalyst, and specific steps were basically the same as those of the Example 1, and the difference is:

(9) During the active metal loading of step 4, the loading amount of zinc was about 8 wt %.

(10) The aromatization catalyst finally obtained in Example 2 was referred to as catalyst B.

Example 3

(11) This embodiment provides a method for preparing an aromatization catalyst, comprising steps of:

(12) 1. a nano-scale HZSM-5 molecular sieve with Si/Al ratio of 25 was physically mixed with pseudoboehmite at a ratio of 9:1 at room temperature to obtain a catalyst precursor.

(13) 2. an ion exchange modification of the catalyst precursor was performed by a method of constant temperature water bath, in particular, sodium hydroxide is dissolved in deionized water and mixed with the catalyst precursor to obtain a mixture, and then placing the mixture in a 90° C. water bath and stirring for 2 hours, so that the loading amount of sodium is about 0.5 wt %, a treated catalyst precursor is obtained, and then drying the treated catalyst precursor at about 120° C. for about 8 hours and then calcining the treated catalyst precursor at about 540° C. for about 4 hours.

(14) 3. a first modification treatment of the catalyst precursor after the ion exchange modification is carried out by an equal volume impregnation method, in particular, dissolving ammonium dihydrogen phosphate in deionized water, and then impregnating the catalyst precursor, controlling a mass ratio of an aqueous solution of ammonium dihydrogen phosphate to the catalyst precursor to be (1.0±0.2):1, so that the loading amount of phosphorus is about 1 wt %; after the impregnation was completed, aging the resulting catalyst precursor at about 20° C. for about 6 hours, drying the catalyst precursor at about 120° C. for about 8 hours, and calcining the catalyst precursor at about 540° C. for about 4 hours.

(15) 4. a hydrothermally treatment of the catalyst precursor after the first modification treatment is conducted at a temperature of about 300° C. in a 100% steam atmosphere for about 6 hours.

(16) 5. active metal loading of the hydrothermally treated catalyst precursor is carried out by an equal volume impregnation method: dissolving both ammonium dihydrogen phosphate and zinc nitrate in a 0.1 mol/L citric acid solution to obtain an impregnation liquid; controlling a mass ratio of the impregnation liquid to the catalyst precursor after the hydrothermally treatment to be (1.0±0.2): 1, an impregnation temperature to be about 30° C., an impregnation time to be about 15 hours, so that the loading amount of phosphorus is about 1 wt %, and the loading amount of zinc is about 5 wt %; after the impregnation was completed, then aging the impregnated catalyst precursor at about 28° C. for about 6 hours, drying the impregnated catalyst precursor at about 120° C. for about 8 hours in an air atmosphere, and calcining the impregnated catalyst precursor at 540° C. for about 4 hours so as to obtain the aromatization catalyst, which was referred as catalyst C.

Example 4

(17) This embodiment provides a method for preparing an aromatization catalyst, and specific steps thereof were basically the same as those of the Example 1, and the differences were that:

(18) In step 3, a first modification treatment of the catalyst precursor after the ion exchange modification is also carried out by an equal volume impregnation method, but a modification element used in the first modification treatment was lanthanum (La), in particular, lanthanum nitrate was dissolved in deionized water, so that the loading amount of lanthanum is 2 wt %, and aging was performed at about 23° C. for about 6 hours; then drying was performed at about 120° C. for about 8 hours, and finally calcination was performed at about 540° C. for about 8 hours.

(19) The finally obtained aromatization catalyst was referred to as catalyst D.

Example 5

(20) This embodiment provides a method for preparing an aromatization catalyst, and specific steps thereof are basically the same as those of the Example 1, and the differences were that:

(21) In step 1, the mass ratio of HZSM-5 molecular sieve to pseudoboehmite was 9:1;

(22) In step 3, a first modification treatment of the catalyst precursor after the ion exchange modification is also carried out by an equal volume impregnation method, but a modification element used in the first modification treatment was sodium (Na), in particular, sodium nitrate was dissolved in deionized water, a loading amount of sodium was controlled to be 0.5 wt %; and then aging was carried out at about 26° C. for about 6 hours; then drying was carried out at about 120° C. for about 8 hours, and finally calcination was carried out at about 540° C. for about 8 hours in turn.

(23) The finally obtained aromatization catalyst was referred to as catalyst E.

Example 6

(24) This embodiment provides a method for preparing an aromatization catalyst, and specific steps thereof are basically the same as those of the Example 1, and the difference was that:

(25) In the active metal loading of step 5, the loading amount of zinc was 12 wt %.

(26) The finally obtained aromatization catalyst was referred to as catalyst F.

Examples 7-12

(27) FCC gasoline fractions of 60° C.˜100° C. (an olefin content was 38.9 wt %, an aromatic content was 3.97 wt %) as raw materials were subjected to aromatization reactions in a small fixed bed reactor, wherein aromatization catalysts used in Examples 7-12 were the aromatization catalysts prepared in Examples 1-6, namely, catalyst A to catalyst F, and aromatization reaction conditions were the same, which were 320° C., atmospheric pressure, volume hourly space velocity of 1 h.sup.−1, reaction time of 30 h, reaction results were shown in Table 1.

(28) Component analysis was performed on aromatics in the aromatization reaction products obtained in the above examples, wherein C6 aromatic (benzene) content was less, about 0.7˜0.9 wt %, accounting for 3%˜4% of a total mass of the aromatics; C7˜C9 aromatic content was the highest, accounting for about 90% of the total mass of the aromatics, and the rest was aromatics of C10 and above.

(29) Therefore, the aromatization reaction products may be used as a gasoline blending component, and meet the requirements for gasoline products in the national VI/Beijing VI automotive gasoline standards (GB17930-2016): olefin content ≤15˜18 v %, aromatic content below 35 wt %, benzene content less than 0.8 wt %.

Example 13

(30) A FCC gasoline fraction of 60° C.˜100° C. (an olefin content was 38.9 wt %, an aromatic content was 3.97 wt %) as a raw material was subjected to an aromatization reaction in a small fixed bed reactor, wherein an aromatization catalysts used was the aromatization catalyst prepared in Example 1, namely, catalyst A, and aromatization reaction conditions were 320° C., atmospheric pressure, volume hourly space velocity of 1 h.sup.−1, reaction time of 200 h, a reaction result was shown in Table 1.

(31) Component analysis was performed on aromatics in the aromatization reaction products obtained in the above examples, wherein C6 aromatic (benzene) content was less, accounting for about 3% of a total mass of the aromatics; C7˜C9 aromatic content was the highest, accounting for 90% of the total mass of the aromatics, and the rest was aromatics of C10 and above.

(32) The aromatization reaction product may be used as a gasoline blending component, and meets the requirements for gasoline products in the national VI/Beijing VI automotive gasoline standards (GB17930-2016): olefin content 15 v %, aromatic content below 35 wt %, benzene content less than 0.8 wt %.

Example 14

(33) The aromatization catalyst which subjected to the aromatization reaction in Example 13 was first dried at 500° C. in a nitrogen atmosphere, and then regenerated for 4 hours under regeneration conditions of a temperature of 550° C. and an oxygen partial pressure of 0.35 kPa so as to obtain a regenerated aromatization catalyst.

(34) A FCC gasoline fraction of 60° C.˜100° C. (an olefin content was 38.9 wt %, an aromatic content was 3.97 wt %) as a raw material was subjected to an aromatization reaction by using the regenerated aromatization catalyst in a small fixed bed reactor, and aromatization reaction conditions were 320° C., atmospheric pressure, volume hourly space velocity of 1 h.sup.−1, reaction time of 200 h, a reaction result was shown in Table 1.

(35) Component analysis was performed on aromatics in the aromatization reaction product obtained in this example, wherein C6 aromatic (benzene) content was less, accounting for about 3% of a total mass of the aromatics; C7˜C9 aromatic content was the highest, accounting for 90% of the total mass of the aromatics, and the rest was aromatics of C10 and above.

Comparative Example 1

(36) This embodiment provides a method for preparing an aromatization catalyst, and specific steps thereof are basically the same as those of the Example 1, and the difference was that:

(37) the catalyst precursor was not subjected to the ion exchange modification of step 2, and directly subjected to steps 3, 4 and 5.

(38) The aromatization catalyst finally obtained in Comparative Example 1 was referred to as catalyst G.

(39) Catalyst G was evaluated using the same raw material and aromatization reaction conditions as that in Examples 7-12. The aromatization reaction lasted for 71 hours, and the catalytic activity basically kept stable. Through calculation, the liquid yield was 98.7% and selectivity was 63.00%. After reacted for 72 hours, the olefin conversion rate significantly decreased to 53%; continuing the reaction, the olefin conversion rate was decreased to 50% or less, so that a single-pass activity was only 3˜4 days (the single-pass activity was an activity that olefin conversion rate maintains can be maintained at 50% or more).

(40) Component analysis was performed on aromatics therein, wherein C6 aromatic (benzene) content was accounted for about 12% of a total mass of the aromatics; C7˜C9 aromatic content was the highest, accounting for about 81% of the total mass of the aromatics, and the rest was aromatics of C10 and above.

Comparative Example 2

(41) An aromatization catalyst was prepared in this comparative example according to the steps 1-2 and steps 4-5 in the Example 1, that is, after the ion exchange modification was carried out, without proceeding the first modification treatment, directly performing the hydrothermal treatment and active metal loading of the step 4, and the second modification treatment of step 5.

(42) The aromatization catalyst finally obtained in Comparative example 2 was referred to as catalyst H.

(43) Performances of the catalyst H were evaluated by using the same raw materials and aromatization reaction conditions as in Examples 7-12, and the reaction time was 30 hours, a reaction result was shown in Table 1.

(44) As can be seen from Table 1, the liquid yield and selectivity were significantly decreased by using the aromatization catalyst obtained without the first modification treatment.

Comparative Example 3

(45) An aromatization catalyst was prepared in the present comparative example according to the steps 1-4 of Example 1, and after the active metal loading was carried out, the second modification treatment was not performed.

(46) The aromatization catalyst finally obtained in Comparative example 3 was referred to as catalyst I.

(47) Performances of the catalyst I were evaluated by using the same raw materials and aromatization reaction conditions as in Examples 7-12, and the reaction time was 30 hours, a reaction result was shown in Table 1.

(48) As can be seen from Table 1, the liquid yield and selectivity were significantly decreased by using the aromatization catalyst obtained without the second modification treatment.

Comparative Example 4

(49) The present comparative example provides a method for preparing an aromatization catalyst, and specific steps thereof are basically the same as those in the Example 1, and the difference was that:

(50) In step 4, the catalyst precursor after being subjected to the first modification treatment was directly subjected to the active metal loading without the hydrothermal treatment.

(51) The aromatization catalyst finally obtained in Comparative example 4 was referred to as catalyst J.

(52) Performances of catalyst J were evaluated by using the same raw materials and aromatization reaction conditions as in Examples 7-12, and the reaction time was 30 hours. A reaction result was shown in Table 1.

(53) As can be seen from Table 1, the liquid yield and selectivity were significantly decreased by using the aromatization catalyst obtained without the hydrothermal treatment.

(54) TABLE-US-00001 TABLE Example or Comparative No. of Liquid yield/ Product/wt % Aromatic Example catalyst wt % olefin aromtic selectivity/% Example 7 A 99.6 10.1 23.9 76.45 Example 8 B 99.2 11.3 21.5 70.45 Example 9 C 99.4 10.8 22.6 73.41 Example 10 D 99.3 10.6 22.8 73.62 Example 11 E 98.9 10.5 21.9 69.80 Example 12 F 98.7 12.0 20.3 67.50 Example 13 A 98.8 12.3 20.1 67.51 Example 14 A 99.3 11.1 20.0 63.86 Comparative H 83.2 14.3 8.8 21.66 Example 2 Comparative I 79.2 19.2 7.5 20.24 Example 3 Comparative J 76.6 23.1 5.3 9.30 Example 4

(55) Finally, it should be noted that the foregoing embodiments are merely intended for describing the technical solutions of the present disclosure other than limiting the present disclosure. Although the present disclosure is described in detail with reference to the foregoing embodiments, persons of ordinary skill in the art should understand that they may still make modifications to the technical solutions described in the foregoing embodiments or make equivalent substitutions to some or all technical features thereof, and these modifications or substitutions do not make the essence of corresponding technical solutions departs from the scope of the technical solutions of embodiments of the present disclosure.