CN114054076A

CN114054076A - Catalyst for catalyzing aromatization of light gasoline and preparation method thereof

Info

Publication number: CN114054076A
Application number: CN202010781382.1A
Authority: CN
Inventors: 李景锋; 柏介军; 张永泽; 向永生; 王高峰; 常晓昕; 姚文君; 高海波; 谢元; 李平智
Original assignee: Petrochina Co Ltd
Current assignee: Petrochina Co Ltd
Priority date: 2020-08-06
Filing date: 2020-08-06
Publication date: 2022-02-18

Abstract

The invention relates to a catalyst for catalyzing aromatization of light gasoline and a preparation method thereof. The catalyst takes a compound formed by alumina and a step hole ZSM-5 molecular sieve as a carrier and Ni₂P is an active metal component. The preparation method of the catalyst comprises the steps of preparing the alumina and step hole ZSM-5 molecular sieve compound carrier by the conventional procedure, and then adding Ni with proper concentration²⁺After the impregnation liquid of the species is impregnated into the carrier, the high-dispersion Ni loaded by the alumina and step hole ZSM-5 molecular sieve compound carrier is directly obtained without high-temperature roasting after aging and drying²⁺Species, finally introducing the Ni²⁺The species is placed in a fixed bed reactor, and PH generated outside the reactor by using an organic phosphating agent or an inorganic phosphating agent₃Under the hydrogen condition, carrying out the phosphorization reaction to obtainObtaining the target catalyst. The catalyst shows good aromatization performance for catalyzing light gasoline.

Description

Catalyst for catalyzing aromatization of light gasoline and preparation method thereof

Technical Field

The invention relates to the field of aromatization catalysts, in particular to a catalyst for catalyzing light gasoline aromatization and a preparation method thereof.

Background

FCC gasoline in gasoline pools in China accounts for about 65 percent, and the contents of sulfur and olefin are high. Upgrading the quality of gasoline in the national VIA/B stage, and limiting the olefin content to be not more than 18/15 v% on the basis of maintaining the sulfur content to be 10 mg/kg. The requirement that olefins be limited to no more than 10 v% is based on U.S. gasoline quality standards, and it is speculated that the trend toward future gasoline quality upgrades is to continue to reduce olefin content and reduce octane number loss. Currently, the FCC gasoline clean technology capable of simultaneously realizing deep desulfurization, substantial olefin reduction and octane number loss reduction is a hydro-upgrading technology, such as a GARDES-II technology, an MPHG-II technology, a PHG-M technology and the like. The common characteristic of the technology is that the full-range gasoline is cut into light gasoline fraction and heavy gasoline fraction, the light gasoline fraction and the heavy gasoline fraction are etherified and hydro-modified respectively, and finally the etherified light gasoline fraction and the hydro-modified heavy gasoline fraction are blended to obtain blending components meeting the quality standard of the existing gasoline. However, with the future implementation of ethanol standard gasoline (E10), where refiners change from producing motor gasoline to producing ethanol gasoline blending components, light gasoline etherification units will not be able to perform the tasks of gasoline olefin reduction and octane number restoration.

Light gasoline aromatization can convert olefin in FCC light gasoline into aromatic hydrocarbon with high octane number, and can play the roles of reducing olefin and recovering octane number of future gasoline. In an aromatization catalyst, a ZSM-5 molecular sieve is applied more, and the main problems of low gasoline yield and poor catalyst stability exist. At present, the aromatization selectivity and stability of a ZSM-5 molecular sieve catalyst are improved mainly by optimizing the mass transfer efficiency of the ZSM-5 molecular sieve and modifying the metal surface. CN201410628681.6 provides a preparation method of a catalytic cracking light gasoline aromatization catalyst; the preparation method of the catalyst mainly comprises the steps of modification of the nano ZSM-5 molecular sieve, preparation of the carrier, preparation of the catalyst and the like. The nano ZSM-5 molecular sieve has short pore passage and high mass transfer efficiency, can reduce the low-carbon olefin in the catalytic cracking light gasoline to the maximum extent and ensure that the octane number is not reduced or even improved after the surface modification is carried out on one or two metals of rare earth or cobalt, molybdenum, nickel, gallium and zinc, but the nano ZSM-5 molecular sieve has small crystal grains, is difficult to separate in the preparation process and is not beneficial to industrial production. CN 02133112.X provides a catalyst for catalyzing aromatization of gasoline and its application process, and the catalyst comprises the following components by weight percent: the content of the noble metal is 0.1-1.0 m%; the content of the K-type zeolite is 50.0-90.0 m%; wherein K₂The O content is 1.0-5.0 m%; the balance being binder. The catalyst can aromatize the catalytic gasoline after hydrodesulfurization to achieve the purposes of reducing the olefin content and reducing the octane number loss, but the catalyst contains noble metals such as platinum, palladium and the like, so that the cost of the catalyst is increased, and sulfur poisoning is easy to occur.

A great deal of research results show that the supported high-dispersion nickel phosphide (Ni)₂P) catalyst not only has the performances of hydrofining, dehydrogenation, hydroisomerization and the like similar to noble metal platinum, but also has low price and good sulfur resistance. Currently, the supported high-dispersion Ni with the most industrial application prospect₂The P catalyst is prepared by a method of hypophosphite radical (H)₂PO₂ ^-) Phosphine (PH)₃) And divalent nickel ions. CN200810234685.0 by H₂PO₂ ^-And Ni²⁺The supported Ni with higher active component dispersity and good catalytic activity is obtained at lower temperature₂And (3) a P catalyst. In the preparation of the catalyst, H₂PO₂ ^-Heated to cause disproportionation to produce pH₃、P、PO₃ ^2-、PO₄ ^3-Low pH of₃And Ni²⁺Reduction reaction is carried out to generate Ni₂P, but the reaction temperature is too high, H₂PO₂ ^-Disproportionation reaction is rapid and partial PH is produced₃Too late with Ni²⁺Some nickel phosphate (e.g., NiP) may be formed by the reaction₄O₁₁) (ii) a Residual PO₃ ^2-、PO₄ ^3-Etc. may occupy a portion of the channels of the catalyst. CN201510232332.7 discloses a loaded Ni₂P catalyst and its phosphorization preparation method, said supported Ni₂The P catalyst is prepared through loading nickel salt onto carrier to obtain loaded nickel oxide, and phosphorizing the loaded nickel oxide catalyst in reactor to convert nickel oxide into Ni₂And P. The prepared catalyst has Ni₂The P has high loading, good dispersity, high purity and good hydrogenation performance. However, the valence state and aggregation degree of the nickel oxide loaded by the method are not well controlled, and the nickel oxide species are not easy to be completely converted into pure-phase Ni in the phosphating process₂P, and the organic phosphating agent used generates elemental P during the in-situ thermal decomposition, which leads to the blockage of the reactor system.

Disclosure of Invention

The nanometer ZSM-5 molecular sieve used for the light gasoline aromatization catalyst is not beneficial to industrial production due to small crystal grains, the used noble metal is high in price and poor in sulfur resistance, and the supported high-dispersion Ni₂The invention aims to provide Ni for catalyzing aromatization of light gasoline₂The P catalyst has carrier comprising alumina and step hole ZSM-5 molecular sieve and active metal component Ni₂P。

The step hole ZSM-5 molecular sieve used in the invention not only has good diffusion and mass transfer performance, but also avoids the problems of difficult separation and difficult industrial production caused by small crystal grains of the nanometer ZSM-5 molecular sieve. Wherein, in the composite carrier composed of the step hole ZSM-5 molecular sieve and the alumina, the content of the step hole ZSM-5 molecular sieve is 60-80 wt%, the content of the alumina is 20-40 wt%, and the dry basis mass ratio of the step hole ZSM-5 molecular sieve to the alumina is 3.0-4.0.

Ni used in the invention₂P not only has the hydrogenation/dehydrogenation performance similar to platinum, but also has low price and good sulfur resistance. According to the invention, it is preferred, among others, that Ni is present in the catalyst in a proportion based on the total weight of the catalyst₂The content of P in the catalyst is 0.2-20.0 wt% calculated by NiO.

The invention will contain Ni²⁺After the impregnation liquid of the species is impregnated into the composite carrier, the high-dispersion Ni is preferably obtained directly without high-temperature roasting²⁺Species of which this is Ni²⁺All of the species being phosphated into highly dispersed Ni₂P lays the foundation.

The invention is in high dispersion of Ni²⁺In the process of phosphating species, the pH generated outside the device by using an organic or inorganic phosphating agent₃For highly dispersed Ni²⁺The species is subjected to a phosphorization reaction to be completely converted into highly dispersed pure phase Ni₂P avoids the problem that the reactor system is blocked due to the generation of simple substance P in the decomposition process of the organic phosphine in the reactor and the residual PO in the catalyst pore channel during the decomposition of hypophosphite₃ ^2-、PO₄ ^3-And the like.

The invention also aims to provide a preparation method of the catalyst for catalyzing light gasoline aromatization, which mainly comprises the following steps:

(1) preparation of alumina and step hole ZSM-5 molecular sieve compound carrier

Mixing the step-hole ZSM-5 molecular sieve with alumina raw powder, respectively adding an extrusion aid and a glue-containing solvent aqueous solution, kneading, molding, drying and roasting to obtain the alumina and step-hole ZSM-5 molecular sieve composite carrier.

(2) Alumina and step hole ZSM-5 molecular sieve compound carrier loaded with high-dispersion Ni²⁺Species (II)

According to the water absorption rate of the composite carrier and the Ni of the target catalyst²⁺Content of metal species, preparing Ni-containing solution with appropriate concentration²⁺Impregnating the impregnation liquid into a carrier, aging and drying the impregnation liquid, and directly obtaining the high-dispersion Ni loaded by the alumina and step hole ZSM-5 molecular sieve composite carrier without high-temperature roasting²⁺Species of the species.

(3) Highly dispersed Ni₂Preparation of P catalyst

Loading the above-mentioned high-dispersion Ni²⁺Placing the alumina of the species and the step hole ZSM-5 molecular sieve compound carrier in a fixed bed reactor, and utilizing the PH generated outside the reactor by an organic phosphating agent or an inorganic phosphating agent₃Under the condition of hydrogen making it undergo the process of phosphorization reaction so as to obtain the invented catalyst for catalyzing aromatization of light gasoline.

Wherein, in the step (1), the average pore diameter, the BET specific surface area and the silicon/aluminum atomic ratio of the step-hole ZSM-5 molecular sieve are respectively 2-20nm and 300-500m²/g、5:1-100:1；

In the step (1), the alumina raw powder can be a commonly used aluminum source, such as pseudo-boehmite powder, aluminum hydroxide powder, SB powder and the like;

in the step (1), preferably, in the forming process, the dry basis weight ratio of the step hole ZSM-5 molecular sieve to the alumina can be controlled to be 3.0-3.7: 1; based on the total weight of the catalyst carrier dry base, the weight contents of the extrusion aid and the peptizing agent are respectively 6-8 wt% and 3-4 wt%, the extrusion aid can be sesbania powder, polyacrylamide, graphite, lubricating oil and the like, and the peptizing agent can be nitric acid, hydrochloric acid, acetic acid, citric acid and the like;

in the step (1), preferably, after drying at the temperature of 120 ℃ and 150 ℃ for about 3-5 hours and roasting at the temperature of 500 ℃ and 550 ℃ for about 3-5 hours, the composite carrier of the alumina and the step-hole ZSM-5 molecular sieve is prepared;

in the step (2), Ni is preferably contained²⁺The impregnating solution of the species is prepared by adopting nickel sulfate, ammonium nickel sulfate,One or more of nickel chloride, nickel bromide, nickel iodide, nickel carbonate, nickel acetate, basic nickel carbonate, nickel oxalate, nickel formate, nickel acetylacetonate and the like;

in the step (2), it is preferable that the Ni-containing material is impregnated by the same volume impregnation or the supersaturation impregnation⁺²An impregnation solution of the species;

in the step (2), preferably, after the impregnation, the high dispersion Ni loaded by the alumina and step hole ZSM-5 molecular sieve compound carrier is prepared after the normal temperature aging for about 6 to 8 hours and the drying at 90 to 120 ℃ for about 4 to 6 hours⁺²A species;

in the step (3), the organic phosphating agent preferably comprises one or more of triethyl phosphine, tripropyl phosphine, tributyl phosphine, triisopropyl phosphine, di-tert-butyl phosphine, triphenyl phosphine, trioctyl phosphine, tri-p-tolyl phosphine, diphenyl methyl phosphine and the like;

in the step (3), preferably, the inorganic phosphating agent comprises one or more of hypophosphorous acid, sodium hypophosphite, ammonium hypophosphite, nickel hypophosphite and the like;

it is preferable in the step (3) that the concentration of the phosphine in the hydrogen gas is 10000-; the volume space velocity of the hydrogen is 1.0 to 3.0h^-1(ii) a The phosphating temperature is 150 ℃ and 400 ℃; the phosphating time is 12-48 h; the phosphating pressure is 0.1-1.0 MPa.

Compared with the prior art, the catalyst for catalyzing the aromatization of the light gasoline and the preparation method thereof provided by the invention have the following characteristics:

(1) the step hole ZSM-5 molecular sieve used by the catalyst not only has good diffusion and mass transfer performance, but also avoids the problems of difficult separation and difficult industrial production caused by small crystal grains of the nano ZSM-5 molecular sieve;

(2) ni used for catalyst₂P not only has the hydrogenation/dehydrogenation performance similar to platinum, but also has low price and good sulfur resistance;

(3) preparation of the catalyst first Ni²⁺After the impregnation liquid of the species is impregnated into the composite carrier, high-dispersion Ni is directly obtained without high-temperature roasting²⁺Species, then PH produced ex situ by organic or inorganic phosphatizing agents₃For high dispersion Ni²⁺The species is subjected to a phosphorization reaction to be completely converted into highly dispersed pure phase Ni₂P avoids the problem that the reactor system is blocked due to the generation of simple substance P in the decomposition process of the organic phosphine in the reactor and the residual PO in the catalyst pore channel during the decomposition of hypophosphite₃ ^2-、PO₄ ^3-And the like.

Detailed Description

The following examples illustrate the invention in detail: the present example is carried out on the premise of the technical scheme of the present invention, and detailed embodiments and processes are given, but the scope of the present invention is not limited to the following examples, and the experimental methods without specific conditions noted in the following examples are generally performed according to conventional conditions.

Example 1

Catalyst a prepared in this example contains NiO 5.0 wt%, 74.4 wt% of mesoporous-macroporous ZSM-5 molecular sieve, and 20.6 wt% of alumina, based on the weight of the catalyst.

Weighing 375g (self-made, 344m specific surface area) of the step-hole ZSM-5 molecular sieve²150g of pseudo-boehmite powder HC-07 (produced by Shandong Xingdu chemical Co., Ltd., the water loss of the prepared alumina is about 30 wt%) and 32.5g of sesbania powder are uniformly mixed, 16.9g of concentrated nitric acid (65 wt%) and 180g of deionized water are added, the mixture is fully kneaded and extruded into a clover strip shape with the thickness of 1.7mm in an extruding machine, the clover strip shape is dried at the temperature of 120 ℃ for about 4 hours and roasted at the temperature of 550 ℃ for about 4 hours, and the carrier of the alumina and the step hole ZSM-5 molecular sieve composite with the length of 3-10mm is obtained by cooling, slitting and sieving the mixture.

Then, according to the water absorption rate (42 wt%) of the carrier, the content (5.0 wt%) of NiO of the target catalyst and the amount of the carrier, preparing an aqueous solution containing 62.45g of nickel sulfate, soaking the aqueous solution onto 450g of the composite carrier in an equal volume, aging the composite carrier at room temperature for about 8 hours, and drying the composite carrier at 120 ℃ for about 4 hours, and then loading the alumina and the step-hole ZSM-5 molecular sieve composite carrier with high-dispersion Ni⁺²Species of the species.

High-molecular Ni loaded by the alumina and step hole ZSM-5 molecular sieve compound carrier⁺²Placing the species in a fixed bed reactor, and using sodium hypophosphitepH generated outside the apparatus₃The concentration of phosphine in hydrogen is 12000ppm, the phosphating temperature is 300 ℃, the phosphating pressure is 0.5MPa, and the volume space velocity of hydrogen is 2.0h^-1Under the condition of (1), phosphorizing the catalyst for 24 hours to obtain Ni for catalyzing aromatization of light gasoline₂P catalyst A.

Example 2

The catalyst prepared in this example was B, which was prepared in the same manner as in example 1, except that Ni was contained in the catalyst₂The content of P: NiO 1.0 wt%, step-hole ZSM-5 molecular sieve 75.8 wt%, and alumina 23.2 wt%, based on the weight of the catalyst.

Example 3

The catalyst prepared in this example was C, which was prepared in the same manner as in example 1, except that Ni was contained in the catalyst₂The content of P: NiO 10.0 wt%, step-hole ZSM-5 molecular sieve 69.6 wt%, and alumina 30.4 wt%, based on the weight of the catalyst.

Example 4

The catalyst prepared in this example was D and prepared in the same manner as in example 1, except that the phosphating agent used was ammonium hypophosphite.

Example 5

The catalyst prepared in this example was E, which was prepared in the same manner as in example 1, except that the phosphating agent used was triphenylphosphine.

Example 6

The catalyst prepared in this example was F, which was prepared in the same manner as in example 1, except that Ni was incorporated in the nickel chloride⁺²An impregnation solution of the species.

Example 7

The catalyst prepared in this example was G and the procedure was the same as in example 1, except that the phosphating pressure was 0.2 MPa.

Example 8

The catalyst prepared in the embodiment is H, and the preparation steps are different from the preparation steps of the embodiment 1, the impregnation liquid is impregnated into a carrier, and then the carrier is roasted at 550 ℃ for 6 hours to obtain multivalent Ni loaded by an alumina and step hole ZSM-5 molecular sieve composite carrier^x+Species of the species.

Example 9

In this example, the aromatization performance of the catalyst A, B, C, D, E, F, G, H of the present invention on FCC light gasoline was evaluated on a small fixed bed reactor using catalytic light gasoline with a temperature of less than 70 ℃ as a feedstock (the contents of saturated hydrocarbon, aromatic hydrocarbon and olefin were 40.5 v%, 0.2 v% and 59.3 v%, respectively).

And respectively filling the precursors of the catalyst into small fixed bed reactors, filling the catalyst into the small fixed bed reactors by 10mL, and carrying out in-situ phosphorization according to the phosphorization program in implementation after the air tightness is qualified.

After the phosphating is finished, switching FCC light gasoline for replacement for 2h, reducing the reaction pressure to 0.1MPa, raising the reaction temperature to 400 ℃, and keeping the volume space velocity for 3.0h^-1The hydrogen/oil volume ratio was adjusted to 250, and samples were taken for analysis after 72 hours of reaction.

Table 1 is aromatization reaction data on FCC light gasoline for the catalyst A, B, C, D, E, F, G, H of the present invention. As can be seen from Table 1, C₅ ⁺The conversion rate of olefin is 61.3-66.0 v%, the increment of aromatic hydrocarbon is 7.3-11.2 v%, and the product C₅ ⁺The liquid yield is 83.2-88.7 v%, which indicates that the FCC light gasoline can effectively carry out aromatization reaction on the catalyst of the invention.

TABLE 1 aromatization reaction data of the catalyst of the present invention on FCC light gasoline

The catalyst of the present invention	X，v％	ΔC_aro，v％	Y，wt％
				A	65.4	10.5	85.4
B	63.9	9.6	83.2
				C	61.3	7.3	88.7
D	66.5	11.2	86.3
				E	65.4	10.7	85.4
F	63.7	11.0	86.0
				G	65.9	10.7	85.8
H	66.0	11.0	86.0

In table 1: x is C₅ ⁺Conversion of olefins; delta C_aroIs an aromatic hydrocarbon increment; y is product C₅ ⁺Liquid yield.

The present invention may be embodied in other specific forms without departing from the spirit or essential attributes thereof, and it is therefore intended that all such changes and modifications as fall within the true spirit and scope of the invention be considered as within the following claims.

Claims

1. The catalyst for catalyzing aromatization of light gasoline is characterized by that its carrier is a composite carrier formed from alumina and step hole ZSM-5 molecular sieve, and its active metal component is Ni₂P。

2. The catalyst for catalyzing the aromatization of light gasoline according to claim 1, wherein the composite carrier contains a step hole ZSM-5 molecular sieve in an amount of 60 to 80 wt% and an alumina in an amount of 20 to 40 wt%.

3. The catalyst for catalyzing the aromatization of light gasoline according to claim 2 wherein the composite support has a dry basis mass ratio of the step pore ZSM-5 molecular sieve to alumina of 3.0 to 4.0.

4. The catalyst for catalyzing the aromatization of light gasoline as claimed in claim 1, wherein the average pore diameter, the BET specific surface area and the silicon/aluminum atomic ratio of the step-hole ZSM-5 molecular sieve are respectively 2-20nm and 300-500m²/g、5:1-100:1。

5. The catalyst for catalyzing the aromatization of light gasoline according to claim 1 characterized in that based on the total weight of the catalyst, Ni₂The content of P in the catalyst is 0.2-20.0 wt% calculated by NiO.

6. A preparation method of a catalyst for catalyzing light gasoline aromatization is characterized by comprising the following steps:

(1) preparation of Complex Carrier

Mixing the step-hole ZSM-5 molecular sieve with alumina raw powder, adding an extrusion aid and a glue-containing solvent aqueous solution, kneading, molding, drying and roasting to obtain a composite carrier;

(2) composite carrier loaded with high-dispersion Ni²⁺Species (II)

Disposition of Ni-containing²⁺Impregnating the impregnation liquid into a composite carrier, aging and drying the composite carrier, and directly obtaining the loaded high-dispersion Ni without high-temperature roasting²⁺A complex carrier of a species;

(3) preparation of the catalyst

Loading the above-mentioned high-dispersion Ni²⁺Placing the compound carrier of the species in a fixed bed reactor, and utilizing the PH generated outside the reactor by using an organic phosphating agent or an inorganic phosphating agent₃And carrying out a phosphating reaction on the gasoline in the presence of hydrogen to finally obtain the catalyst for catalyzing aromatization of light gasoline.

7. The method for producing a catalyst for catalyzing the aromatization of light gasoline according to claim 6 wherein the Ni content²⁺The impregnation liquid of the species is prepared by at least one of nickel sulfate, nickel ammonium sulfate, nickel chloride, nickel bromide, nickel iodide, nickel carbonate, nickel acetate, basic nickel carbonate, nickel oxalate, nickel formate and nickel acetylacetonate.

8. The method of claim 6, wherein the organophosphorous agent comprises at least one of triethylphosphine, tripropylphosphine, tributylphosphine, triisopropylphosphine, di-t-butylphosphine, triphenylphosphine, trioctylphosphine, tri-p-tolylphosphine, and diphenylmethylphosphine.

9. The method of claim 6, wherein the inorganic phosphating agent comprises at least one of hypophosphorous acid, sodium hypophosphite, ammonium hypophosphite and nickel hypophosphite.

10. The method of claim 6, wherein the conditions of the phosphating reaction are as follows: the concentration of phosphine in hydrogen is 10000-^-1The phosphorization temperature is 150-.