Use of organic framework porous solid acid

This application is a U.S. national stage of PCT/CN2012/000938, filed on 6 Jul. 2012, which claims priority from Chinese patent application No. 201110191278.8, filed on 8 Jul. 2011. The entire contents of both of those applications are hereby incorporated into this application by reference.

The present invention relates to an application of organic framework porous solid acid.

Solid acid is widely used as the development of chemistry industry, especially plays a very important role in the field of petrochemicals and fine chemicals. Traditional acid catalysts comprise zeolite molecular sieve, vulcanized metal oxides, acid-functionalized mesoporous materials, heteropolyacids and so on, but the defects of which, such as hydrophilic framework structure, the pore size limitation of zeolite material and the like, affect the wide application of inorganic solid acid material. Compared to the acid catalyst with traditional inorganic framework, pure organic framework solid acid materials get more and more widely studied for unique framework hydrophobic property, simple and convenient functionalizing process and better catalytic property.

It is known that a strong acidic cation resin, with divinyl benzene and styrene copolymer as its framework, and sulfonate as active functional group, may be used as a new type of organic framework solid acid material. The hydrophobic framework structure and high acid site content of the strong acidic cation resin make it possible to be used in the fields of acid catalytic reaction and ion exchange, comprising esterification, ester exchange and etherification, with very good results ( J. Catal. 2008, Vol. 254, p. 205.). And industrialization of that has been achieved nowadays, and plays a very important role in the industrial application. However, the defects, such as low specific surface area, poor porous structure and framework with poor stability, limit its application in various fields.

One objective of the present invention is to provide an application of organic framework porous solid acid, in which porous poly divinyl benzene is used as material for good swelling property, the organic framework obtained from sulfonation reaction solid acid is used for the catalyst of catalytic esterification and acylation reaction It has advantages of high crosslinking degree, high stability, and has large specific surface area and various porous structures.

A synthetic method of organic framework porous solid acid according to the invention comprises:

(1) 2 g divinyl benzene (DVB) monomer is added into a mixture solvent comprising 0.03-0.05 g azobisisobutyronitrile, 10-20 ml tetrahydrofuran and 1-2 ml water, which is stirred for more than 3 hours at ambient temperature and pressure followed by hydrothermal treatment for 1-2 days at 75-150° C., then the obtained product is taken out, opened and volatilized at the room temperature to obtain polydivinylbenzene (PDVB) having high specific surface area and various mesoporous structures;

(2) 2-3 g polydivinylbenzene (PDVB) is ground into 200-mesh powder and degassed for 10 h under nitrogen condition for 10 h;

(3) 2.0 g polydivinylbenzene (PDVB) blocks are added into 1,1′,2-trichloroethane, then PDVB material rapidly swells, explodes and cracks into small blocks accompanied by rapid volume expansion of PDVB;

(4) 30 milliliter 1,1′,2-trichloroethane is mixed homogenously with 70 mL concentrated sulphuric acid having a mass concentration of 98%, with silver sulfate being added as a catalyst, the mixture is then stirred uniformly followed by adding processed polydivinylbenzene (PDVB) obtained from (3) with severe agitation, and the temperature of sulfonation is increased to 90° C. for 12 h, the product is filtered and washed with dioxane and then washed with water till neutral, dryed at 80° C., subsequently activated by 0.1M dilute sulphuric acid for 4 hours, then washed with quantity of water till neutral, finally dried and at ready.

A synthetic method of novel solid acid material according to the invention, having efficient stable structure, high specific surface area, high sulfonate content, is demonstrated in detail with examples as follows.

In the examples, the sample name consists of two parts: the PDVB represents mesoporous polydivinylbenzene, and “—SO 3 H” represents sulfonate functionalized mesoporous polydivinylbenzene material.

The sulfonate-functionalized mesoporous polypolydivinylbenzene according to the invention has a large specific surface area (523 m 2 /g).

The sulfonated mesoporous polypolydivinylbenzene material according to the invention has relatively high sulfonate content (2.45 mmol/g).

The sulfonate-functionalized mesoporous polypolydivinylbenzene according to the invention has a stable framework structure (575° C.) and a stable acid site (305° C.).

The sulfonate-functionalized mesoporous polypolydivinylbenzene according to the invention exhibits good catalytic activity and regeneration property in the catalytic esterification and Friedel-Crafts acylation reaction, and the activity is reduced by 11.3% after being recycled for 5 times.

The feature of the present invention is that the polypolydivinylbenzene material, which has various mesoporous structures, specific surface area of 600-700 m 2 /g, an average pore size of 15-23 nm and a pore volume of 0.7-1.4 ml/g, is synthesized by solvothermal method. Said material has a very good swelling property to most of organic solvent comprising benzene and its homologue, alkanes, alcohols and etc. Using this feature in combination with various porous structures and large specific surface area of this material, a new type of stable and highly efficient organic framework solid acid material is successfully synthesized by a new synthesis path following the order of “swelling-sulfonation”. Meanwhile, the sulfonated material reserves large specific surface area and various porous structures, the sulfonate content after sulfonation is 2.0-3.5 mmol/g, and the volume of hydrogen ion exchange is 2.2-3.7 mmol/g. The specific surface area is 280-500 m 2 /g. Compared to aforementioned patents, the solid acid according to the present invention has unique framework hydrophobic property, simple and convenient functionalizing process, better catalytic property and regeneration function.

Table 1 shows the catalytic activity of synthetic sulfonated material in esterification reaction and acylation reaction.