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Zn-modified hierarchically porous hzsm‑5 catalyst and its application in liquefied gas aromatization

A technology of ZSM-5 and catalyst, applied in the field of HZSM-5 molecular sieve, can solve the problems of coking deactivation, acid catalytic performance reduction, and limitation of large-scale application, and achieve the goals of reducing cracking, increasing selectivity, and improving stability Effect

Active Publication Date: 2017-03-01
TAIYUAN UNIV OF TECH
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  • Abstract
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  • Claims
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AI Technical Summary

Problems solved by technology

However, when HZSM-5 is used as a low-carbon hydrocarbon aromatization catalyst, not only the hydrogen transfer (or dehydrogenation) of low-carbon hydrocarbons to generate olefins occurs at the strong acid site, but also the cracking side reaction at the strong acid site occurs, which is prone to coking and loss. live, which limits its large-scale application
In order to solve the problem of deactivation of aromatization catalysts, most of the relevant researches are currently improving molecular sieves from two aspects: one is to modify ZSM-5 with metals such as Zn and Ga to effectively adjust the acidity, Reduce side reactions to improve catalyst stability; on the other hand, improve catalyst life by improving molecular sieve structure, reducing diffusion resistance, and improving carbon capacity. Among them, high temperature treatment, steam treatment and acid treatment all make micropores Mesopores are formed by destruction, but the increase of Si / Al ratio reduces the acid catalytic performance of molecular sieves, which is unfavorable for the aromatization of liquefied gas

Method used

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  • Zn-modified hierarchically porous hzsm‑5 catalyst and its application in liquefied gas aromatization
  • Zn-modified hierarchically porous hzsm‑5 catalyst and its application in liquefied gas aromatization
  • Zn-modified hierarchically porous hzsm‑5 catalyst and its application in liquefied gas aromatization

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0030] 10g of HZSM-5 (nSiO 2 / nAl 2 o 3 =38) dissolved in 600ml NaOH (0.1 mol / L) solution, 50 o C and stirred for 30min, the solution was cooled and the pH value was adjusted to 7 with dilute nitric acid, then suction filtered, washed, 100 o C was dried for 3 hours to obtain alkali-modified Na-type ZSM-5, labeled as NaZSM-5(AT);

[0031] NaZSM-5(AT) was treated with 0.5 mol / L NH 4 NO 3 The solution was ion-exchanged three times, filtered, washed, dried and 500 o C was roasted for 3 h to obtain alkali-modified hydrogen ZSM-5, labeled as HZSM-5(AT);

[0032] Mix HZSM-5(AT) and pseudo-boehmite AlO(OH) at a mass ratio of 4:6, stir evenly, add dilute nitric acid solution with a mass concentration of 1% and form a mass and knead repeatedly, 100 o C drying 3h, 500 oC is calcined for 3 h, and the industrial catalyst obtained is marked as HZSM-5(AT)+A;

[0033] Using Zn(NO 3 ) 2 The solution was fully impregnated with HZSM-5(AT)+A in an equal volume under negative pressure, ...

Embodiment 2

[0035] 10g of HZSM-5 (nSiO 2 / nAl 2 o 3 =50) dissolved in 600ml NaOH (0.5 mol / L) solution, 100 o C and stirred for 300min, the solution was cooled and the pH value was adjusted to 7 with dilute nitric acid, then suction filtered, washed, 150 o C dried for 12 hours to obtain alkali-modified Na-type ZSM-5, labeled as NaZSM-5(AT);

[0036] NaZSM-5(AT) was treated with 3 mol / L NH 4 NO 3 The solution was ion-exchanged three times, filtered, washed, dried and 550 o C was roasted for 12 h to obtain alkali-modified hydrogen ZSM-5, labeled as HZSM-5(AT);

[0037] Mix HZSM-5(AT) and pseudo-boehmite AlO(OH) at a mass ratio of 8:2, stir evenly, add dilute nitric acid solution with a mass concentration of 10% and form a mass and knead repeatedly, 150 o C drying 12h, 550 o C is calcined for 12 h, and the industrial catalyst obtained is marked as HZSM-5(AT)+A;

[0038] Using Zn(NO 3 ) 2 The solution was fully impregnated with HZSM-5(AT)+ A in an equal volume under negative pressur...

Embodiment 3

[0040] 10g of HZSM-5 (nSiO 2 / nAl 2 o 3 =38) dissolved in 600ml NaOH (0.2 mol / L) solution, 60 o C and stirred for 120min, the solution was cooled and the pH value was adjusted to 7 with dilute nitric acid, then suction filtered, washed, 110 o C dried for 6h to obtain alkali-modified Na-type ZSM-5, labeled as NaZSM-5(AT);

[0041] NaZSM-5(AT) was treated with 1.0 mol / L NH 4 NO 3 The solution was ion-exchanged three times, filtered, washed, dried and 520 o C is roasted for 3 hours to obtain alkali-modified hydrogen ZSM-5, marked as HZSM-5(AT);

[0042] Mix HZSM-5(AT) and pseudo-boehmite AlO(OH) at a mass ratio of 7:3, stir evenly, add dropwise 3% dilute nitric acid solution and knead repeatedly, 120 o C drying 3h, 550 o C is calcined for 6h, and the industrial catalyst obtained is marked as HZSM-5(AT)+A;

[0043] Using Zn(NO 3 ) 2 The solution was fully impregnated with HZSM-5(AT)+A in an equal volume under negative pressure, and stood at room temperature for 24h, 120...

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Abstract

The invention relates to a Zn modified multi-level pore HZSM-5 catalyst, a NaOH solution is used for alkali treatment of HZSM-5 molecular sieve to prepare the HZSM-5 (AT), the the HZSM-5 (AT) is mixed with binder pseudo-boehmite mixed stone and roasted to obtain industrial catalyst HZSM-5 (A-T) + A, and finally Zn (NO3) 2 modification of the HZSM-5 (A-T) + A is performed by equivalent-volume impregnation method to obtain Zn / (HZSM-5 (A-T) + A). The alkali modified industrial catalyst is used in liquefied gas aromatization reaction, due to the formation of a small amount of mesopores, the stability is improved; and after combination of alkali modification and Zn modification, the stability is improved, at the same time due to the existence of proper amount of Zn-L medium-strong acid center, he synergetic catalysis effect of B and L acid and strong and weak acids can be improved, splitting action of strong B acid and the generation of C9 + in liquid aromatic hydrocarbons can be reduced, and the BTEX selectivity can be improved.

Description

technical field [0001] The invention relates to a HZSM-5 molecular sieve, in particular to a Zn-modified multi-stage porous HZSM-5 catalyst applied to the aromatization of liquefied gas, and the use of the catalyst in the aromatization of liquefied gas. Background technique [0002] Benzene, toluene and xylene (BTX), as the main products of liquefied petroleum gas (LPG) aromatization, are important chemical basic raw materials, widely used in synthetic fibers, resins, rubber and various fine chemicals, and are in great demand At the same time, toluene and xylene are becoming more and more popular as important blending components for the production of high-octane gasoline. Therefore, LPG aromatization technology can not only realize the value-added utilization of LPG, but also alleviate the tight supply of aromatics, which has strong practical significance. [0003] ZSM-5 zeolite molecular sieve has been widely used in the field of catalysis, especially in the petrochemical ...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): B01J29/40C10G50/00
Inventor 张瑞珍王翠邢普温少波赵欣
Owner TAIYUAN UNIV OF TECH
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