Main applications of hydrogenated terphenyl_Kain Industrial Additives

Background and overview^[1-2]

The development of heat transfer oil has a history of more than 60 years abroad. The original heat transfer oil was produced in the early 1930s and was Dowtherm developed by the American Dow Chemical Company. In the 1950s, the United States used a deep refining process to produce mineral oil-based heat transfer oil. Since the 1960s, Japan and Germany have launched ethylbiphenyl-based and benzyltoluene-based heat transfer oils with excellent performance, and then other countries have launched similar products one after another. In the late 1970s, my country began to develop and produce synthetic heat transfer oils. However, the level of industrialization at that time was still low, and it was not reasonably developed and developed slowly. In the 1970s, some foreign manufacturers added various types of thermal oils to improve the high-temperature properties of their products. additive. In my country, with the introduction of some industrial equipment, thermal oil technology has also been introduced. At the same time, a few research and production units in the domestic petrochemical industry have also begun research and trial production of thermal oil. In the 1980s, my country’s petrochemical, chemical fiber and chemical industries developed rapidly, and new processes had an increasing demand for high-temperature heating. Therefore, some domestic companies switched from the production of synthetic heat transfer oils to the production of mineral oil-type heat transfer oils. In the 1990s, more people in China recognized the advantages of heat transfer oil. In addition, industrial application technology became increasingly mature and closely followed the development of the times, which led to a greater expansion of the application fields of heat transfer oil.

Hydrogenated terphenyl is a heat carrier used in high-temperature liquid phase. It is the product of partial hydrogenation of terphenyl. It has good thermal stability, high liquid phase use temperature, low freezing point (<-25℃), and heavy fraction ( 330℃-420℃), low vapor pressure, and low operating pressure when used in liquid phase. It is widely used in the fields of synthetic fiber, synthetic resin, medicine and petrochemical industry. When hydrogenated terphenyl is operated at high temperature for a long time, thermal cracking, polycondensation and coking will occur. Cracking produces low-boiling components and high-boiling components, causing the flash point to drop, carbon residue and acid value to increase, and it is prone to explosion, corrosion of equipment, Accumulation of coke, etc., affects the normal operation of the equipment. Therefore, hydrogenated terphenyl must be replaced or regenerated in a timely manner. At present, the simple fractionation treatment method is used. Since some azeotropes are difficult to remove, the carbon residue and acid value of hydrogenated terphenyl after treatment still cannot meet the requirements.

Apply^[2-5]

Hydrogenated terphenyl is a kind of heat transfer oil with excellent performance. Its main component is a mixture of partially hydrogenated terphenyl isomers, which is obtained by partial hydrogenation of o-, m- and p-terphenyl mixtures in different proportions (the degree of saturation is 39%). Hydrogenated terphenyl has excellent thermal stability, anti-oxidation and low vapor pressure properties. It is widely used in petrochemical, synthetic fiber, synthetic resin, medicine, printing and dyeing and other industries, high-temperature heat conduction, heating equipment systems, chemical fiber polymerization (polyester, Nylon polymerization, dry spandex spinning), silicone monomer synthesis, trichlorosilane and polysilicon, pharmaceuticals, pesticides, dye intermediates and other fine chemicals, biodiesel. Examples of its application are as follows:

1) Prepare a release agent for precision casting, which belongs to the technical field of release agents. The present invention is a release agent for precision casting, which is composed of kerosene, 320 heat transfer oil, dibutyltin dilaurate, hydrogenated terphenyl, butyl acrylate, octylphenol polyoxyethylene ether, titanium dioxide, quicklime and zinc oxide The formula consists of: 5 to 8 parts by weight of kerosene, 20 to 25 parts of 320 thermal oil, 6 to 7 parts of dibutyltin dilaurate, 27 to 30 parts of hydrogenated terphenyl, and 10 to 13 parts of butyl acrylate. parts, 8 to 12 parts of octylphenol polyoxyethylene ether, 3 to 5 parts of titanium dioxide, 11 to 16 parts of quicklime, and 7 to 9 parts of zinc oxide. The invention can be used normally for a long time in the range of 50 to 180°C without deterioration or failure. Therefore, the surface of the core will not adhere to the surface of the mold, thereby improving the demoulding effect and reducing the scrap rate. It has no corrosive effect on castings, and castings will not develop mildew or corrosion when stored for more than half a year.

2) Prepare a binder for blast furnace mud with good opening performance, which belongs to the field of blast furnace mud. The steps are: (1) Weigh 40 to 50 parts of asphalt and 4 to 6 parts of hydrogenated terphenyl by mass, add asphalt and hydrogenated terphenyl to the reaction kettle in sequence, and stir and mix at a temperature of 55 to 60°C for 20 minutes. ; (2) Weigh 10 to 12 parts of silicone resin, 8 to 11 parts of furan resin and 11 to 15 parts of melamine formaldehyde resin according to mass parts. Control the temperature rise rate of the reaction kettle in step (1) to 3 to 4°C/min. , when the temperature of the reaction kettle reaches 72~76°C, add silicone resin, furan resin and melamine formaldehyde resin to the reaction kettle in sequence, and continue to stir and mix for 16 minutes. The preparation method of the present invention has simple processing and low production cost. The binder prepared by the present invention is added to configure the cannon mud. The cannon mud has good opening performance, is resistant to erosion and erosion by high-temperature slag iron, and does not pollute the environment.

3) Prepare a high-temperature synthetic heat transfer oil, which is a cyclohexylbiphenyl composition, or a mixture of the cyclohexylbiphenyl composition and hydrogenated terphenyl in any proportion, which can replace the industry Hydrogenated terphenyl thermal fluid widely used in the industry. The cyclohexylbiphenyl composition has excellent thermal stability. It can be used alone as a high-temperature heat transfer oil and run in a working environment of 350°C for a long time. It can also be mixed with hydrogenated terphenyl in any proportion to prepare heat transfer oil. It is very good. It makes up for the shortcomings of insufficient sources of hydrogenated terphenyl raw materials in industry. Moreover, the raw materials for preparing the cyclohexylbiphenyl composition are simple and easy to obtain, the process conditions are simple, the reaction process is easy to control, and the catalyst can be recycled.

Preparation^[2]

A method for preparing hydrogenated terphenyl, comprising the following steps:

(1) Biphenyl synthesis:

① Mixing: Mix pure benzene and catalyst in the circulation tank, and then pump it into the benzene evaporator for evaporation; ② Cracking: A certain amount of benzene vapor enters the heat exchanger and is preheated before entering the tubular reactor. Benzene steam reacts in the tubular reactor; ③ Cooling: The reaction gas enters the heat exchanger from the tubular reactor, and is cooled after heat exchange, so that the gas benzene, biphenyl and terphenyl are cooled into liquids;

(2) First distillation: Place the benzene and biphenyl liquids in step (1) into a distillation kettle, first recover benzene under normal pressure as the synthetic raw material for biphenyl in step (1), and then Perform vacuum distillation to obtain biphenyl;

(3) Second distillation: perform a second distillation of the residue at the bottom of the rectification kettle, and send the low boiling matter to the rectification kettle of step (3) to obtain terphenyl;

(4) Hydrogenation: Hydrogenate the terphenyl in step (3) in a hydrogenation autoclave to obtain hydrogenated terphenyl finished product.