RU2622046C1 - Method of obtaining dialcilsulfides - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention relates to a process of preparation of dialkyl sulfides from a "disulphide oil", by the reaction of "disulfide oil" with methanol in the presence of a gamma alumina catalyst, at atmospheric pressure, at a temperature of 350-400°C, the molar ratio of methanol to "disulfide oil" (2.6-3.2):1, the contact time 0.13-0.95 s.

EFFECT: dialkyl sulfides are flotation agents, gas odorants, starting reagents for obtaining various valuable substances.

1 tbl, 12 ex

Description

The invention relates to methods for producing organosulfur compounds, in particular to dialkyl sulfides, which are flotation reagents, gas odorants, starting reagents to produce various valuable substances.

For preparative purposes, dialkyl sulfides are most often obtained by reacting haloalkyls with alkali metal sulfides or with alkanethiols, as well as by reacting hydrogen sulfide or alkanethiols with alkenes or alcohols. These methods are often based on the use of expensive and inaccessible reagents and are technologically sophisticated.

In the oxidative desulfurization of mercaptan-containing gas condensates, oils and oil products in huge quantities, a mixture of lower dialkyl disulfides is obtained, mainly with R = C ₁ -C ₂ , released in the form of the so-called "disulfide oil". These petroleum disulfides are currently of limited use, and are mainly burned with emission of harmful emissions.

There is no information on the use of petroleum disulfides to obtain dialkyl sulfides on their basis.

The objective of the invention is to provide a method for processing "disulfide oil" into a mixture of dialkyl sulfides.

The problem is solved in that dialkyl sulfides are prepared by the reaction of a “disulfide oil” with methanol in the presence of a gamma alumina catalyst in the gas phase at atmospheric pressure, a temperature of 350-400 ° C, a molar ratio of methanol to “disulfide oil” (2.6-3.2): 1, contact time 0.13-0.95 s.

Used "disulfide oil" obtained by the oxidative demercaptonization of petroleum products at the Novo-Ufa Refinery, containing 34 wt.% Dimethyldisulfide, 50 wt.% Methylethyl disulfide and 16 wt.% Diethyl disulfide. The γ-Al ₂ O ₃ catalyst used has a specific surface area of 275 m ² / g. According to X-ray studies, there are very few strong proton centers on the surface of this catalyst, but a significant number of strong Lewis acid centers and major centers of medium strength. Methanol is chemisorbed on γ-Al ₂ O ₃ to form surface-bound methoxyl groups (CH ₃ O), and dialkyl disulfides are easily decomposed by contact with the catalyst to form RS groups upon contact with the catalyst. The interaction of RS-groups with methoxy groups leads to the formation of methylalkyl sulfides. Some RS-groups experience deep decomposition with the release of hydrogen sulfide. The reaction of hydrogen sulfide with methanol produces dimethyl sulfide.

The synthesis of dialkyl sulfides is carried out in the gas phase at atmospheric pressure, in a flow unit on a fixed catalyst bed. Helium from a balloon is passed through saturators with a certain speed - the first with "disulfide oil", the second with methanol. A mixture of "disulfide oil", methanol and helium at a certain temperature enters the reactor filled with catalyst, heated by a non-inertia furnace. The reaction mixture through a six-way valve enters the chromatograph LHM-8MD. A gas sample is periodically taken using a two-way valve for chromatographic and chromatographic mass spectrometric analyzes. According to the results of the analysis, the conversion of reagents in% is determined, the product yields in mol. % and selectivity of product formation in relation to their yield to conversion,%. The contact time is equal to the ratio of the volume of the catalyst (in cm ³ ) to the gas flow rate in cm ³ / s at room temperature and atmospheric pressure.

The invention is illustrated by the following examples shown in the table.

Example 1

The γ-Al ₂ O ₃ catalyst is loaded into the reactor and a mixture of “disulfide oil” with methanol in helium is passed through it at atmospheric pressure, a temperature of 300 ° C, a contact time of 0.48 s, a molar ratio of methanol to “disulfide oil” of 3: 1 .

The conversion of "disulfide oil" is 26%, the yield of dimethyl sulfide 15 mol.%, The yield of methylethyl sulfide 10 mol.%. The total dialkyl sulfide selectivity is 96%.

Example 2

Example 1 is repeated with the difference that the contact time is 1.0 s.

Examples 3-4.

Example 1 is repeated with the difference that the temperature is 350 ° C, the contact time is 0.26-0.95 s

Examples 5-7

Example 1 is repeated with the difference that the temperature is 400 ° C and the contact time is 0.13-0.49 s.

Examples 8-12

Example 1 is repeated with the difference that the temperature is 350 ° C, the contact time is ~ 0.7 s and the molar ratio of methanol to “disulfide oil is 0-3.2

Examples 1-2 show that the process proceeds with a small yield of dilkyl sulfides

Examples 8-9 show that at a molar ratio of reactants 0-1.5, dialkyl sulfides are formed with insufficient selectivity.

Claims (1)

A method of producing dialkyl sulfides from a “disulfide oil”, characterized in that it is obtained by reacting a “disulfide oil” with methanol in the presence of a gamma alumina catalyst, at atmospheric pressure, a temperature of 350-400 ° C, a molar ratio of methanol to “disulfide oil” ( 2.6-3.2): 1, contact time 0.13-0.95 s.