RU2459792C1 - Method of producing cyclohexane - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention relates to a method of producing cyclohexane from unsaturated hydrocarbons, characterised by that a mixture of acetylene and natural gas in ratio of 46-48:52-54 mol % undergoes mechanical activation at temperature 20°C for 3-10 minutes in the presence of crystalline quartz.

EFFECT: present method enables to obtain cyclohexane in a single step, without additional pressure and at low temperatures.

2 cl, 4 ex

Description

The invention relates to the chemical industry, in particular to a method for producing cyclohexane.

Mostly cyclohexane is obtained from benzene. The most commonly used are the hydrogenation of benzene to cyclohexane. Known methods for producing cyclohexane by liquid-phase hydrogenation of benzene (US Pat. No. 5189233 USA .; Pat. No. 2139843 of the Russian Federation, Pat. 6750374 USA, Application 2716190 France, Pat. No. 2196123 of the Russian Federation, Pat. 6153805 USA, Pat. 6187080 USA, Pat. No. 2235086 RF). A typical problem with the hydrogenation of benzene to cyclohexane is adverse reactions. In particular, isomerization to methylcyclopentane is undesirable. In addition, at higher temperatures, ring cleavage occurs, leading to undesired C5 and lighter products. The disadvantage of this method is the need for desulfurization of raw materials.

The closest to the proposed method is a method for the hydrogenation of benzene in a shelf-type adiabatic reactor by contacting benzene with a catalyst at a temperature of 140-240 ° C, a pressure of 3-6 MPa, a bulk feed rate of 0.5-2.0 h ^-1 in the presence of a hydrogen-containing gas (Pat. No. 2400463). The disadvantages of this method are the necessity of using high temperature and pressure in the process of producing cyclohexane and the complex technological design of the process.

The objective of the proposed method is to obtain cyclohexane mechanochemically from a mixture of acetylene with natural gas, allowing the process to be carried out in one stage, without creating additional pressure and at low temperatures.

The technical result is achieved due to the mechanochemical treatment of a mixture of acetylene with natural gas at a ratio of 46 ÷ 48: 52 ÷ 54 mol.%, A temperature of 20 ° C for 3-10 minutes in the presence of crystalline quartz with a particle size of 2-4 mm.

The process of producing cyclohexane is carried out in a mechanochemical reactor of a centrifugal planetary ball mill of the AGO-2 type, at a reactor speed of 1820 rpm. Grinding steel balls and crystalline quartz (particle size 2-4 mm) are placed in a hermetically sealed mill reactor. A mixture of acetylene with natural gas is pumped into the reactor (having previously removed the air) at a pressure of 1 atm at a ratio of 46 ÷ 48: 52 ÷ 54 mol.%. The composition of natural gas includes methane (97 mol.%), Ethane (2.3 mol.%), Propane (0.6 mol.%), Other gases (0.1 mol.%). In the process of mechanochemical activation in the presence of quartz, acetylene is converted to benzene. Part of the resulting benzene is hydrogenated with hydrogen released during mechanical destruction of natural gas hydrocarbons, with the formation of cyclohexane at a temperature of 20 ° C (due to external cooling of the reactors) for 3-10 minutes. The selectivity of the proposed method for cyclohexane reaches 25 mol.%.

Acetylene and linear hydrocarbons are analyzed by gas chromatographic methods using a thermal conductivity detector. C ₁ -C ₆ hydrocarbons are separated by gas-liquid chromatography in a column filled with a spherochrome; stationary liquid phase - triethylene glycol butyrate. Non-hydrocarbon gas components are determined by the gas adsorption method in a column filled with CaA zeolite as an adsorbent. The carrier gas is argon. Benzene and cyclohexane are determined on a Crystal-2000M gas-liquid chromatograph with a flame detector.

Case Studies

Example 1. A mixture of the composition of acetylene (46 mol.%) + Natural gas (54 mol.%) Is subjected to mechanical treatment in the reactor-activator of the mill AGO-2 for 3 minutes, under the conditions described above.

The resulting gas mixture contains 13 mol.% Cyclohexane.

Example 2. A mixture of the composition acetylene (46 mol.%) + Natural gas (54 mol.%) Was subjected to mechanical treatment in the reactor activator of the AGO-2 mill for 5 minutes, under the conditions described above.

The resulting gas mixture contains 25 mol.% Cyclohexane.

Example 3. A mixture of the composition acetylene (46 mol%) + natural gas (54 mol%) was subjected to mechanical treatment in the reactor activator of the AGO-2 mill for 10 minutes, under the conditions described above.

The resulting gas mixture contains 5 mol.% Cyclohexane.

Example 4. A mixture of the composition acetylene (48 mol%) + natural gas (52 mol%) was subjected to mechanical treatment in the reactor activator of the AGO-2 mill for 5 minutes, under the conditions described above.

The resulting gas mixture contains 23 mol.% Cyclohexane.

In the gas phase, after the mechanical treatment of the mixtures described in the examples, in addition to cyclohexane, acetylene, benzene, hydrogen, methane, and ethane are present.

Thus, the proposed method allows to obtain cyclohexane directly from acetylene and natural gas in one stage by the mechanochemical method at room temperature and atmospheric pressure.

Claims (2)

1. The method of producing cyclohexane from unsaturated hydrocarbons, characterized in that the mixture of acetylene and natural gas at a ratio of 46 ÷ 48: 52 ÷ 54 mol.% Is subjected to mechanochemical activation at a temperature of 20 ° C for 3-10 minutes in the presence of crystalline quartz. 2. The method according to claim 1, characterized in that the use of quartz with a particle size of 2-4 mm