Title of Invention	A PROCESS FOR CONTINUOUSLY PREPARING METHYL MERCAPTAN FROM HYDROGEN SULPHIDE AND METHANOL
Abstract	Process for preparing methyl mercaptan, characterized in that the syntheses of hydrogen sulphide and methyl mercaptan are coupled to one another by mixing the reaction mixture which leaves the reactor for hydrogen sulphide synthesis under pressure with methanol and introducing it into the reactor for methyl mercaptan synthesis under pressure, a pressure difference being established between the reactors used for the two syntheses which allows the hydrogen sulphide/methanol mixture to flow in the direction of the methyl mercaptan reactor wherein the pressure in the reactor for hydrogen sulphide synthesis is > 9 to 20 bar and that in the methyl mercaptan reactor is 9 to < 20 bar and the synthesis of hydrogen sulphide is effected at a temperature between 300 and 500°C.

Title of Invention

A PROCESS FOR CONTINUOUSLY PREPARING METHYL MERCAPTAN FROM HYDROGEN SULPHIDE AND METHANOL

Abstract

Process for preparing methyl mercaptan, characterized in that the syntheses of hydrogen sulphide and methyl mercaptan are coupled to one another by mixing the reaction mixture which leaves the reactor for hydrogen sulphide synthesis under pressure with methanol and introducing it into the reactor for methyl mercaptan synthesis under pressure, a pressure difference being established between the reactors used for the two syntheses which allows the hydrogen sulphide/methanol mixture to flow in the direction of the methyl mercaptan reactor wherein the pressure in the reactor for hydrogen sulphide synthesis is > 9 to 20 bar and that in the methyl mercaptan reactor is 9 to < 20 bar and the synthesis of hydrogen sulphide is effected at a temperature between 300 and 500°C.

Full Text	REVISED TEXT VERSION Process for preparing methyl mercaptan The present invention relates to a process for continuously preparing methyl mercaptan from hydrogen sulphide and methanol in direct connection with the preparation of hydrogen sulphide. Methyl mercaptan in particular is an industrially important intermediate, for example for the synthesis of methionine and for the synthesis of dimethyl sulphoxide and dimethyl sulphone. It is currently prepared predominantly from methanol and hydrogen sulphide by reaction over a catalyst composed of aluminium oxide. Methyl mercaptan is commonly synthesized in the gas phase at temperatures between 300 and 500°C and at pressures between 1 and 50 bar. In addition to the methyl mercaptan and water formed, the product gas mixture comprises the unconverted methanol and hydrogen sulphide starting materials and dimethyl sulphide and dimethyl ether as by-products, and also small amounts of polysulphides (dimethyl disulphide). Gases inert in the reaction, such as carbon monoxide, carbon dioxide, nitrogen and hydrogen, are also present in the product gas. The methyl mercaptan formed is removed from this reaction mixture. The reactant gas mixture comprises predominantly hydrogen sulphide and methanol in a molar ratio between 1:1 and 10:1. As explained in DE-1768826, the methyl mercaptan formed is removed from the product gas mixture in several distillation and wash columns at temperatures between 10 and 140°C. The further product streams obtained are excess hydrogen sulphide, methanol, inert gases such as carbon monoxide, carbon dioxide, nitrogen and water. The wash liquid used is preferably methanol. Excess hydrogen sulphide is recycled into the reactor as so- called cycle gas. In addition to hydrogen sulphide, the cycle gas also comprises methanol, methyl mercaptan, dimethyl sulphide and organic components, and consumed hydrogen sulphide and methanol are replaced by supplying fresh media. The overall process for methyl mercaptan preparation can be divided into two sections. The first section comprises the workup of the reactant gas mixture and its conversion to methyl mercaptan. The second sector includes the separation of the product gas mixture to obtain methyl mercaptan and recycling of the unconsumed feedstocks, and also the disposal of wastewater and offgases. For economic viability of the process, minimum capital and operating costs are required. Here, the cost for apparatus and machines in particular, but also the energy demand for the synthesis and workup of the reactant gas mixture, constitutes a high cost factor. For example, large electrical outputs are required for the operation of compressors and of heating and cooling circuits. According to FR 2477538, methyl mercaptan is prepared by compressing fresh hydrogen sulphide gas to 11 bar in a compressor. Thereafter, cycle gas which comprises hydrogen sulphide, dimethyl sulphide, methanol and small amounts of methyl mercaptan and has been recycled from the process is added to the compressed hydrogen sulphide to form the reactant gas mixture. A preheating oven raises the temperature of the gas mixture after the compression to 510°C. In DE 19654515 too, the compression of the reactant gases to operating pressure is described preferentially in two stages, for example with a two-stage compressor, the gas mixture being compressed in the first stage to an intermediate pressure and in the second stage to the operating pressure. The methanol can be injected directly into the first compressor stage. The reactant gas mixture thus obtained is then heated first to an initial temperature of 150 to 250°C and then further to the reaction temperature. At this temperature, the reactant gas mixture passes into the reactor for the formation of methyl mercaptan. Owing to the temperature limit in a compression, the temperature after the second compressor stage can be raised to a maximum of 140°C. This means that the entrance temperature of the hydrogen sulphide before the compression must, for example, be at ambient temperature. Consequently, the hydrogen sulphide prepared beforehand at high temperature must first be cooled and, after the compression, heated again to obtain the reaction temperature for the formation of methyl mercaptan. This cooling and repeated heating requires numerous heat exchangers and high energy costs. Moreover, the hydrogen sulphide for compression should not comprise any impurities or even solids, in order not to damage the compressor. The synthesis of hydrogen sulphide from the elements hydrogen and sulphur is effected typically by introducing a hydrogen into liquid sulphur and a subsequent reaction chamber in the gas phase. Both catalysed and uncatalysed processes are known. The industrial production of hydrogen sulphide from the elements proceeds according to Ullmann's Encyclopedia of Industrial Chemistry, Wiley-VCH, 2002, at temperatures of 450°C and a pressure of 7 bar. CSSR 190792 describes a process variant for preparing hydrogen sulphide, in which high reaction temperatures are avoided by a comparatively complicated series connection of a plurality of reactors. High temperatures are avoided there especially because of corrosion problems. GB 1193040 describes the uncatalysed synthesis of hydrogen sulphide at relatively high temperatures of 400 to 600°C and pressures of 4 to 15 bar. It is stated that the required temperature is determined by the pressure at which the synthesis should proceed. At a pressure of 9 bar, 500°C are accordingly required. Overall, there are numerous publications with different catalysts for preparing hydrogen sulphide. For instance, US 2214859 describes the use of several different metal oxides and metal sulphides with high conversions of hydrogen. US 2863725 describes the use of catalysts such as molybdenum sulphide, cobalt oxide or cobalt molybdate bound to supports such as bauxite or aluminium oxide, in order to prepare substantially sulphur-free hydrogen sulphide. An important point in the preparation of hydrogen sulphide from sulphur and hydrogen is in particular the temperature control. High temperatures are necessary in order to achieve an equilibrium state in which a molar hydrogen:sulphur ratio in the gas phase of about 1:1 is established. Only this enables the synthesis of pure hydrogen sulphide. With increasing pressure, the temperature has to be increased greatly in accordance with the vapour pressure curve of sulphur, in order to achieve the desired molar ratio of 1:1 in the gas phase. In this context, even small differences in the pressure of, for example, 1 bar or less are of great significance. It is an object of the invention to provide a novel process for preparing methyl mercaptan. The invention provides a process for preparing methyl mercaptan, which is characterized in that the syntheses of hydrogen sulphide and methyl mercaptan are coupled to one another by mixing the reaction mixture which leaves the reactor for hydrogen sulphide synthesis under pressure with methanol and introducing it into the reactor for methyl mercaptan synthesis under pressure, a pressure difference being established between the reactors used for the two syntheses which allows the hydrogen sulphide/methanol mixture (reactant gas) to flow in the direction of the methyl mercaptan reactor. This pressure difference is generally less than 1 bar, preferably less than 0.6 bar, and is always greater than 0 bar, the higher pressure being in the reactor for the hydrogen sulphide synthesis. The inventive connection of the reactors for hydrogen sulphide and methyl mercaptan synthesis, in which the reaction mixture leaving the hydrogen sulphide reactor has a pressure higher by from > 0 to 1 bar in comparison to the methyl mercaptan reactor, permits the avoidance of the necessary compression of the hydrogen sulphide, as is known from the prior art. In the reactant gas workup, it is also possible in accordance with the invention to dispense with the cooling to ambient temperature and with the reheating. Moreover, small amounts of impurities and residual amounts of sulphur also do not disrupt continuous production, since the fault-prone compressor for this purpose is not required in accordance with the invention. As a result of the higher pressure in the reactant gas workup, the gas density in the apparatus is also increased, which enables a more compact design with constant residence time. The person skilled in the art is free to select the process steps to be combined to prepare hydrogen sulphide. In one embodiment for the preparation of hydrogen sulphide, hydrogen is introduced into liquid sulphur at a pressure of 8 to 20 bar and converted in a downstream reaction chamber. The entire arrangement is preferably operated at the same temperature. Moreover, the conversion to hydrogen sulphide is preferably effected in the presence of a heterogeneous catalyst. The catalyst is a sulphur-resistant hydrogenation catalyst known from the state of art, which preferably consists of a support, for example silicon oxide, aluminium oxide, zirconium oxide or titanium oxide, and one or more of the active elements molybdenum, nickel, tungsten, vanadium, cobalt, sulphur, selenium, phosphorus, arsenic, antimony and bismuth or preferably, their compounds. The catalyst may be used either in the liquid phase or in the gas phase. Depending on the reaction conditions, especially at high temperatures, it is also possible for a portion of the hydrogen sulphide to be formed without the action of a catalyst. In a further embodiment of the invention, a plurality of, especially two or three, reactors are connected in series. In this case, the hydrogen which has then only been converted partly, together with the hydrogen sulphide formed, is converted in a further reactor for further conversion to hydrogen sulphide, preferably distributed in liquid sulphur and directly in the WE CLAIM: 1. Process for preparing methyl mercaptan, characterized in that the syntheses of hydrogen sulphide and methyl mercaptan are coupled to one another by mixing the reaction mixture which leaves the reactor for hydrogen sulphide synthesis under pressure with methanol and introducing it into the reactor for methyl mercaptan synthesis under pressure, a pressure difference being established between the reactors used for the two syntheses which allows the hydrogen sulphide/methanol mixture to flow in the direction of the methyl mercaptan reactor wherein the pressure in the reactor for hydrogen sulphide synthesis is > 9 to 20 bar and that in the methyl mercaptan reactor is 9 to of hydrogen sulphide is effected at a temperature between 300 and 500°C. 2. Process as claimed in claim 1, wherein the pressure difference in the reactors used for the two syntheses is > 0 to being in the reactor for hydrogen sulphide synthesis. 3. Process as claimed in claims 1 and 2, wherein the pressure in the reaction vessels in both processes is more than 8 bar. 4. Process as claimed in claim 1, wherein the synthesis of hydrogen sulphide is effected in the presence of a heterogeneous catalyst. 5. Process as claimed in claim 4, wherein the synthesis of hydrogen sulphide is effected in the presence of a heterogeneous hydrogenation catalyst. 6. Process as claimed in claim 4, wherein the synthesis of hydrogen sulphide is effected in the presence of a heterogeneous supported catalyst which comprises one or more of the active elements selected from the group of molybdenum, nickel, tungsten, vanadium, cobalt, sulphur, selenium, phosphorus, arsenic, antimony, bismuth, silicon, aluminium, titanium and zirconium or their compounds. 7. Process as claimed in claims 1 to 6, wherein the hydrogen sulphide is prepared in two or more reactors connected in series. 8. Process as claimed in claims 1 to 7, wherein the hydrogen used to prepare hydrogen sulphide comprises further substances. 9. Process as claimed in claim 8, wherein the hydrogen used has a purity greater than 65% by volume. 10. Process as claimed in claims 1 to 9, wherein the reaction mixture leaving the hydrogen sulphide synthesis comprises by -products or starting materials in addition to hydrogen sulphide. 11. Process as claimed in claims 1 to 10, wherein the sulphur present in the reaction mixture leaving the hydrogen sulphide synthesis is removed therefrom under pressure before the mixing with methanol. 12. Process as claimed in claim 11, wherein the mixture is cooled to not more than ~ 120°C during or before the removal of the sulphur and any further sulphur compounds. 13. Process as claimed in claim 11, wherein the hydrogen sulphide-containing reaction mixture, downstream of the reactor, is cooled at a pressure between 9 and 20 bar and liquid sulphur is removed or recycled. 14. Process as claimed in claim 11, wherein the hydrogen sulphide is purified after the hydrogen sulphide synthesis between the two processes by using adsorbents at a pressure between 9 and 20 bar. Process for preparing methyl mercaptan, characterized in that the syntheses of hydrogen sulphide and methyl mercaptan are coupled to one another by mixing the reaction mixture which leaves the reactor for hydrogen sulphide synthesis under pressure with methanol and introducing it into the reactor for methyl mercaptan synthesis under pressure, a pressure difference being established between the reactors used for the two syntheses which allows the hydrogen sulphide/methanol mixture to flow in the direction of the methyl mercaptan reactor wherein the pressure in the reactor for hydrogen sulphide synthesis is > 9 to 20 bar and that in the methyl mercaptan reactor is 9 to synthesis of hydrogen sulphide is effected at a temperature between 300 and 500°C.

Full Text

REVISED TEXT VERSION
Process for preparing methyl mercaptan
The present invention relates to a process for
continuously preparing methyl mercaptan from hydrogen
sulphide and methanol in direct connection with the
preparation of hydrogen sulphide.
Methyl mercaptan in particular is an industrially
important intermediate, for example for the synthesis
of methionine and for the synthesis of dimethyl
sulphoxide and dimethyl sulphone. It is currently
prepared predominantly from methanol and hydrogen
sulphide by reaction over a catalyst composed of
aluminium oxide. Methyl mercaptan is commonly
synthesized in the gas phase at temperatures between
300 and 500°C and at pressures between 1 and 50 bar.
In addition to the methyl mercaptan and water formed,
the product gas mixture comprises the unconverted
methanol and hydrogen sulphide starting materials and
dimethyl sulphide and dimethyl ether as by-products,
and also small amounts of polysulphides (dimethyl
disulphide). Gases inert in the reaction, such as
carbon monoxide, carbon dioxide, nitrogen and hydrogen,
are also present in the product gas. The methyl
mercaptan formed is removed from this reaction mixture.
The reactant gas mixture comprises predominantly
hydrogen sulphide and methanol in a molar ratio between
1:1 and 10:1.
As explained in DE-1768826, the methyl mercaptan formed
is removed from the product gas mixture in several
distillation and wash columns at temperatures between
10 and 140°C. The further product streams obtained are
excess hydrogen sulphide, methanol, inert gases such as
carbon monoxide, carbon dioxide, nitrogen and water.
The wash liquid used is preferably methanol. Excess
hydrogen sulphide is recycled into the reactor as so-
called cycle gas. In addition to hydrogen sulphide, the
cycle gas also comprises methanol, methyl mercaptan,
dimethyl sulphide and organic components, and consumed
hydrogen sulphide and methanol are replaced by
supplying fresh media.
The overall process for methyl mercaptan preparation
can be divided into two sections. The first section
comprises the workup of the reactant gas mixture and
its conversion to methyl mercaptan. The second sector
includes the separation of the product gas mixture to
obtain methyl mercaptan and recycling of the unconsumed
feedstocks, and also the disposal of wastewater and
offgases.
For economic viability of the process, minimum capital
and operating costs are required. Here, the cost for
apparatus and machines in particular, but also the
energy demand for the synthesis and workup of the
reactant gas mixture, constitutes a high cost factor.
For example, large electrical outputs are required for
the operation of compressors and of heating and cooling
circuits.
According to FR 2477538, methyl mercaptan is prepared
by compressing fresh hydrogen sulphide gas to 11 bar in
a compressor. Thereafter, cycle gas which comprises
hydrogen sulphide, dimethyl sulphide, methanol and
small amounts of methyl mercaptan and has been recycled
from the process is added to the compressed hydrogen
sulphide to form the reactant gas mixture. A preheating
oven raises the temperature of the gas mixture after
the compression to 510°C.
In DE 19654515 too, the compression of the reactant
gases to operating pressure is described preferentially
in two stages, for example with a two-stage compressor,
the gas mixture being compressed in the first stage to
an intermediate pressure and in the second stage to the
operating pressure. The methanol can be injected
directly into the first compressor stage. The reactant
gas mixture thus obtained is then heated first to an
initial temperature of 150 to 250°C and then further to
the reaction temperature. At this temperature, the
reactant gas mixture passes into the reactor for the
formation of methyl mercaptan. Owing to the temperature
limit in a compression, the temperature after the
second compressor stage can be raised to a maximum of
140°C.
This means that the entrance temperature of the
hydrogen sulphide before the compression must, for
example, be at ambient temperature. Consequently, the
hydrogen sulphide prepared beforehand at high
temperature must first be cooled and, after the
compression, heated again to obtain the reaction
temperature for the formation of methyl mercaptan. This
cooling and repeated heating requires numerous heat
exchangers and high energy costs. Moreover, the
hydrogen sulphide for compression should not comprise
any impurities or even solids, in order not to damage
the compressor.
The synthesis of hydrogen sulphide from the elements
hydrogen and sulphur is effected typically by
introducing a hydrogen into liquid sulphur and a
subsequent reaction chamber in the gas phase. Both
catalysed and uncatalysed processes are known.
The industrial production of hydrogen sulphide from the
elements proceeds according to Ullmann's Encyclopedia
of Industrial Chemistry, Wiley-VCH, 2002, at
temperatures of 450°C and a pressure of 7 bar.
CSSR 190792 describes a process variant for preparing
hydrogen sulphide, in which high reaction temperatures
are avoided by a comparatively complicated series
connection of a plurality of reactors. High
temperatures are avoided there especially because of
corrosion problems.
GB 1193040 describes the uncatalysed synthesis of
hydrogen sulphide at relatively high temperatures of
400 to 600°C and pressures of 4 to 15 bar. It is stated
that the required temperature is determined by the
pressure at which the synthesis should proceed. At a
pressure of 9 bar, 500°C are accordingly required.
Overall, there are numerous publications with different
catalysts for preparing hydrogen sulphide. For
instance, US 2214859 describes the use of several
different metal oxides and metal sulphides with high
conversions of hydrogen. US 2863725 describes the use
of catalysts such as molybdenum sulphide, cobalt oxide
or cobalt molybdate bound to supports such as bauxite
or aluminium oxide, in order to prepare substantially
sulphur-free hydrogen sulphide.
An important point in the preparation of hydrogen
sulphide from sulphur and hydrogen is in particular the
temperature control. High temperatures are necessary in
order to achieve an equilibrium state in which a molar
hydrogen:sulphur ratio in the gas phase of about 1:1 is
established. Only this enables the synthesis of pure
hydrogen sulphide. With increasing pressure, the
temperature has to be increased greatly in accordance
with the vapour pressure curve of sulphur, in order to
achieve the desired molar ratio of 1:1 in the gas
phase. In this context, even small differences in the
pressure of, for example, 1 bar or less are of great
significance.
It is an object of the invention to provide a novel
process for preparing methyl mercaptan.
The invention provides a process for preparing methyl
mercaptan, which is characterized in that the syntheses
of hydrogen sulphide and methyl mercaptan are coupled
to one another by mixing the reaction mixture which
leaves the reactor for hydrogen sulphide synthesis
under pressure with methanol and introducing it into
the reactor for methyl mercaptan synthesis under
pressure, a pressure difference being established
between the reactors used for the two syntheses which
allows the hydrogen sulphide/methanol mixture (reactant
gas) to flow in the direction of the methyl mercaptan
reactor.
This pressure difference is generally less than 1 bar,
preferably less than 0.6 bar, and is always greater
than 0 bar, the higher pressure being in the reactor
for the hydrogen sulphide synthesis.
The inventive connection of the reactors for hydrogen
sulphide and methyl mercaptan synthesis, in which the
reaction mixture leaving the hydrogen sulphide reactor
has a pressure higher by from > 0 to 1 bar in
comparison to the methyl mercaptan reactor, permits the
avoidance of the necessary compression of the hydrogen
sulphide, as is known from the prior art. In the
reactant gas workup, it is also possible in accordance
with the invention to dispense with the cooling to
ambient temperature and with the reheating. Moreover,
small amounts of impurities and residual amounts of
sulphur also do not disrupt continuous production,
since the fault-prone compressor for this purpose is
not required in accordance with the invention. As a
result of the higher pressure in the reactant gas
workup, the gas density in the apparatus is also
increased, which enables a more compact design with
constant residence time.
The person skilled in the art is free to select the
process steps to be combined to prepare hydrogen
sulphide.
In one embodiment for the preparation of hydrogen
sulphide, hydrogen is introduced into liquid sulphur at
a pressure of 8 to 20 bar and converted in a downstream
reaction chamber. The entire arrangement is preferably
operated at the same temperature.
Moreover, the conversion to hydrogen sulphide is
preferably effected in the presence of a heterogeneous
catalyst. The catalyst is a sulphur-resistant
hydrogenation catalyst known from the state of art,
which preferably consists of a support, for example
silicon oxide, aluminium oxide, zirconium oxide or
titanium oxide, and one or more of the active elements
molybdenum, nickel, tungsten, vanadium, cobalt,
sulphur, selenium, phosphorus, arsenic, antimony and
bismuth or preferably, their compounds. The catalyst
may be used either in the liquid phase or in the gas
phase. Depending on the reaction conditions, especially
at high temperatures, it is also possible for a portion
of the hydrogen sulphide to be formed without the
action of a catalyst.
In a further embodiment of the invention, a plurality
of, especially two or three, reactors are connected in
series. In this case, the hydrogen which has then only
been converted partly, together with the hydrogen
sulphide formed, is converted in a further reactor for
further conversion to hydrogen sulphide, preferably
distributed in liquid sulphur and directly in the
WE CLAIM:
1. Process for preparing methyl mercaptan, characterized in that the
syntheses of hydrogen sulphide and methyl mercaptan are coupled to one
another by mixing the reaction mixture which leaves the reactor for
hydrogen sulphide synthesis under pressure with methanol and
introducing it into the reactor for methyl mercaptan synthesis under
pressure, a pressure difference being established between the reactors
used for the two syntheses which allows the hydrogen sulphide/methanol
mixture to flow in the direction of the methyl mercaptan reactor wherein
the pressure in the reactor for hydrogen sulphide synthesis is > 9 to 20 bar
and that in the methyl mercaptan reactor is 9 to of hydrogen sulphide is effected at a temperature between 300 and
500°C.
2. Process as claimed in claim 1, wherein the pressure difference in the
reactors used for the two syntheses is > 0 to being in the reactor for hydrogen sulphide synthesis.
3. Process as claimed in claims 1 and 2, wherein the pressure in the reaction
vessels in both processes is more than 8 bar.
4. Process as claimed in claim 1, wherein the synthesis of hydrogen sulphide
is effected in the presence of a heterogeneous catalyst.
5. Process as claimed in claim 4, wherein the synthesis of hydrogen sulphide
is effected in the presence of a heterogeneous hydrogenation catalyst.
6. Process as claimed in claim 4, wherein the synthesis of hydrogen sulphide
is effected in the presence of a heterogeneous supported catalyst which
comprises one or more of the active elements selected from the group of
molybdenum, nickel, tungsten, vanadium, cobalt, sulphur, selenium,
phosphorus, arsenic, antimony, bismuth, silicon, aluminium, titanium and
zirconium or their compounds.
7. Process as claimed in claims 1 to 6, wherein the hydrogen sulphide is
prepared in two or more reactors connected in series.
8. Process as claimed in claims 1 to 7, wherein the hydrogen used to
prepare hydrogen sulphide comprises further substances.
9. Process as claimed in claim 8, wherein the hydrogen used has a purity
greater than 65% by volume.
10. Process as claimed in claims 1 to 9, wherein the reaction mixture leaving
the hydrogen sulphide synthesis comprises by -products or starting
materials in addition to hydrogen sulphide.
11. Process as claimed in claims 1 to 10, wherein the sulphur present in the
reaction mixture leaving the hydrogen sulphide synthesis is removed
therefrom under pressure before the mixing with methanol.
12. Process as claimed in claim 11, wherein the mixture is cooled to not more
than ~ 120°C during or before the removal of the sulphur and any further
sulphur compounds.
13. Process as claimed in claim 11, wherein the hydrogen sulphide-containing
reaction mixture, downstream of the reactor, is cooled at a pressure
between 9 and 20 bar and liquid sulphur is removed or recycled.
14. Process as claimed in claim 11, wherein the hydrogen sulphide is purified
after the hydrogen sulphide synthesis between the two processes by using
adsorbents at a pressure between 9 and 20 bar.

Process for preparing methyl mercaptan, characterized in that the syntheses of
hydrogen sulphide and methyl mercaptan are coupled to one another by mixing
the reaction mixture which leaves the reactor for hydrogen sulphide synthesis
under pressure with methanol and introducing it into the reactor for methyl
mercaptan synthesis under pressure, a pressure difference being established
between the reactors used for the two syntheses which allows the hydrogen
sulphide/methanol mixture to flow in the direction of the methyl mercaptan
reactor wherein the pressure in the reactor for hydrogen sulphide synthesis is > 9
to 20 bar and that in the methyl mercaptan reactor is 9 to synthesis of hydrogen sulphide is effected at a temperature between 300 and
500°C.

A PROCESS FOR CONTINUOUSLY PREPARING METHYL MERCAPTAN FROM HYDROGEN SULPHIDE AND METHANOL

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