ZSM-5 type molecular sieve synthesis method

Patent metadata

Field	Value
Publication number	US-9963350-B2
Application number	US-201314648425-A
Country	US
Kind code	B2
Filing date	Nov 28, 2013
Priority date	Nov 29, 2012
Publication date	May 8, 2018
Grant date	May 8, 2018

Abstract

The present invention pertains to the field of molecular sieve synthesis, and relates to a synthesis method of ZSM-5 type molecular sieves. In this method, natural minerals, i.e., natural kaolin and natural diatomite, are used as the total silicon source and aluminum source required for the molecular sieve synthesis, and these two natural minerals are calcinated and subjected to acidic (alkaline) treatment before they are mixed at a certain ratio, and then crystallized under hydrothermal conditions to obtain the product, a ZSM-5 type molecular sieve. The ZSM-5 type molecular sieve obtained by the method according to the present invention is a hierarchical porous material having a crystallinity of 70% to 120% as compared to conventional ZSM-5 type molecular sieves synthesized by using pure chemical reagents, and the silica-to-alumina ratio in the molecular sieve product may be adjusted by varying the ratio of the two minerals in the raw materials for the synthesis. According to the present invention, the range of raw materials for the preparation of molecular sieve materials is broadened, and therefore not only the cost for the molecular sieve production is greatly reduced but also the greenness in the production process of the molecular sieve material is significantly improved.

First claim

The invention claimed is:

1. A synthesis method for producing ZSM-5 molecular sieves, comprising using natural minerals as the total silicon source and an aluminum source needed for the molecular sieve synthesis, and performing hydrothermal crystallization to produce the ZSM-5 molecular sieves, wherein said natural minerals are a mixture of one or more natural minerals having a low silica-to-alumina ratio together with a natural mineral having a high silica-to-alumina ratio, wherein the one or more natural minerals having a low silica-to-alumina ratio have a silica-to-alumina molar ratio of 10 or less and are selected from the group consisting of kaolin, montmorillonite, bentonite, attapulgite and rectorite, and wherein the natural mineral having a high silica-to-alumina ratio is diatomite having a silica-to-alumina molar ratio of 30 or more.

2. The synthesis method of claim 1 , wherein the one or more natural mineral having a low silica-to-alumina ratio is kaolin.

3. The synthesis method of claim 2 , wherein the ZSM-5 molecular sieve is a hierarchical porous material having a silica-to-alumina molar ratio of 2.0 to 49.5, with a crystallinity of 70% to 120% as compared to a conventional ZSM-5 molecular sieve synthesized by using pure chemical reagents.

4. The synthesis method of claim 1 , further comprising the following steps:
(1) activating kaolin with the following process:
(a) mixing kaolin and sodium hydroxide solid in a mass ratio of 3:1 to 1:3, grinding the mixture, and then calcinating the ground mixture at 600 to 1000° C. to obtain activated kaolin for the ZSM-5 molecular sieve synthesis; or
(b) mixing kaolin and a sodium hydroxide solution in a mass ratio of 1:1 to 1:10, and then drying the mixture at 100 to 300° C. to obtain activated kaolin for the ZSM-5 molecular sieve synthesis, wherein the sodium hydroxide solution is prepared by mixing solid sodium hydroxide and water in a mass ratio of 10:1 to 1:5;

(2) activating diatomite with the following process:
(a) calcinating diatomite at 600 to 1000° C. to obtain activated diatomite for the ZSM-5 molecular sieve synthesis; or
(b) mixing diatomite and a sodium hydroxide solution evenly in a mass ratio of 1:1 to 5:1, and then drying at 100 to 300° C. to obtain activated diatomite for the ZSM-5 molecular sieve synthesis, wherein the sodium hydroxide solution is prepared by mixing solid sodium hydroxide and water in a mass ratio of 10:1 to 1:5;

(3) mixing deionized water, a template, and the activated kaolin obtained in step (1) with the activated diatomite obtained in step (2) to obtain an aqueous mixture; adjusting the molar ratio of the aqueous mixture to 0.085-0.4 Na 2 O:SiO 2 :2.0-49.5 Al 2 O 3 :10-60 H 2 O to obtain a synthesis system solution; adjusting the pH value of the synthesis system solution to 9-13; and then conducting crystallization at 140 to 200° C. to obtain a crystallized product; and
(4) cooling and filtering the crystallized product obtained in step (3); to remove the mother liquid; and washing the filter cake with deionized water until neutral; and then drying to obtain the ZSM-5 molecular sieve.

5. The synthesis method of claim 4 , wherein the template is one or a mixture of more than one of tetrapropylammonium bromide, tetraethylammonium bromide, and n-butyl amine, and the template is used in an amount with a molar ratio of 0.01:1 to 0.3:1 with respect to the SiO 2 in the synthesis system.

6. The synthesis method of sieves according to claim 5 , wherein, in step (3), the pH value of the synthesis system solution is adjusted to 9 to 13 with a sulfuric acid solution, stirred at 50 to 75° C. for 0 to 20 h for aging, and then crystallized.

7. The synthesis method of claim 6 , wherein, in step (3), the pH value of the synthesis system solution is adjusted to 10 to 12 by using a sulfuric acid solution.

Assignees

• Univ China Petroleum Beijing
• China Nat Petroleum Corp
• Univ China Petroleum Beijing

Inventors

• Bao Xiaojun
• Yue Yuanyuan
• Li Tiesen
• Liu Haiyan
• He Shengbao
• Yu Jianning

Classifications

• B01J20/18

  Synthetic zeolitic molecular sieves · CPC title

• B01J35/002

  Operations & Transport · mapped topic

• C01B39/38

  Type ZSM-5 · CPC title

• B01J29/40

  of the pentasil type, e.g. types ZSM-5, ZSM-8 or ZSM-11, as exemplified by patent documents US3702886, GB1334243 and US3709979, respectively · CPC title

• C01B39/40 Primary

  using at least one organic template directing agent · CPC title