Method for preparing methylphenol by hydroxylating methylbenzene

Abstract

The invention relates to a method for preparing methylphenol by hydroxylating methylbenzene. The method comprises the following step of: carrying out a contact reaction on the methylbenzene, a solvent, hydrogen peroxide and a catalyst under the hydroxylating reaction condition, wherein the catalyst contains a titanium-silicon molecular sieve in an MFI (Mean Fluorescence Intensity) structure. The method is characterized in that the titanium-silicon molecular sieve in the MFI structure is obtained through acid treatment. The method disclosed by the invention has the advantages of high transformation ratio and good product selectivity and can obtain more para-products.

Description

technical field [0001] The invention relates to a method for preparing cresol by hydroxylation of toluene, and more specifically relates to a method for preparing cresol by hydroxylation of toluene with titanium silicon molecular sieve as a catalyst. Background technique [0002] Cresol, also known as cresol, has three isomers, namely o-cresol, m-cresol and p-cresol, all of which are important chemical raw materials and are widely used in industry, mainly for the production of herbicides, pesticides, Antioxidants, medicines, vitamin E, spices, resins, dyes, etc. [0003] There are two main routes for traditional cresol production. The first route is to separate and extract from coal tar. On the one hand, this route brings serious pollution to the environment, and on the other hand, its raw material supply is becoming more and more limited; the second route is Chemical synthesis methods, including toluene sulfonation alkali fusion method, isopropyl toluene method, toluene ch...

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Problems solved by technology

However, the chemical synthesis method generally has problems: as the toluene sulfonation alkali fusion method needs to use strong acid and strong alkali, which has serious environmental pollution and severe corrosion of equipment (J.E.Bailey, et al., Willey VCH: Weinheim, 1998); The production process of isopropyl toluene method is complicated, and the by-product acetone with low economic value has low atom utilization rate (Shenyang Institute of Chemical Industry, m-cresol group. Pesticide. 1973, 4:64-68); toluene chlorination hydrolysis method needs to use Strong acid and strong alkali solution will pollute the environment (Sun Jialong, et al. Chemical Reagent. 2009, 31(10): 846~848); the phenol alkylation method needs to be carried out at a higher temperature, and the reaction condition requirements are high, and the reaction Co-production of 2,6-dimethylphenol (Weissermel, K.et al., Wiley-VCH: Weinheim.2003); the diazotization hydrolysis method of toluidine needs to go through the diazotization process, the process route is complex, there are more three wastes, Equipment corrosion is serious (Qi Xiaojing, et al., Shanxi Chemical Industry. 2009, 29(6): 16-18)

The method adopts the synthesized titanium-silicon molecular sieve as the catalyst, hydrogen peroxide as the oxidant, and reacts in a three-necked flask at 80-120° C. to generate o-cresol, m-cresol, and p-cresol at the same time, and the specificity of the product is not enough, resulting in Subsequent product separation procedures are complex

[0010] Literature (P.Mukherjee, et al., Ind.Eng.Chem.Res.2007, 46:8657-8664) reported that titanium silicon molecular sieve was used as catalyst, hydrogen peroxide was used as oxidant, water was used as solvent, and the reaction temperature was 80°C. Under solid-liquid-liquid three-phase conditions, toluene was reacted for 8 hours to obtain o-cresol and p-cresol, and the selectivity of cresol reached 100%, but the conversion rate of toluene was low

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