Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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METHOD AND AGENT FOR DESULPHURISATION
The invention relates to desulphurisation and in particular to the purification of streams
(liquid or gas or both) by the partial or complete removal of sulphur compounds, e.g.
hydrogen sulphide, low molecular weight mercaptans, or the like therefrom. The
invention may also be applied to the purification of air or other gas containing sulphur
compounds. The invention relates to a method and a desulphurisation agent.
In one aspect the invention provides a method of reducing the content of a sulphur
compound in stream of gas and/or liquid, the method comprising contacting the stream
with particles of a compound of manganese and particles of a compound of iron
characterised in that the particles are incorporated in a porous carrier, the molar ratio is
from 8:1 to 1:8 (Mn:Fe) and in that the particles are bonded together by a bonding agent
~o form a desulphurisation agent which is contacted with the stream at a temperature
from about 20~ to about 1 50~C.
The desulphurisation is performed, for example, at a temperature preferably from about
40~C to about 1 50~C. Preferably the compounds are the oxides, hydroxides, carbonates,
e.g. hydroxycarbonate or basic carbonate or the like of both manganese and iron. These
active ingredients may be incorporated within a carrier of the invention by simple
impregnation or impregnation/deposition, coforming, precipitation from aqueous
solution or other techniques well known to those skilled in the art of catalyst
AMEN~D SHEET
IPEA/EP
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CA 02266458 1999-03-19
la
preparation. Tlle carrier may be alumina, silica, aluminosilicates or the like. The
content of the carrier material will be in the range 1 to 40% by weight.
E~l~ S~EET
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CA 022664~8 1999-03-19
,
Preferably the compounds are in the relative molar proportions of about 1:1.
In a preferred feature the desulphurisation agent comprises shaped particles. The
particles may be presented in a variety of shapes and sizes preferably as spheres;
extrudates, granules, tablets or the like. The binding agent may be cement, alumina,
clay, silica or organic resins or the like. The agent may require exposure to elevated
temperatures to achieve the optimum bond strength. Preferably the agent includes a
promoter which is one or more of potassium hydroxide, nickel hydroxide and sodium
hydroxide, optionally with a derivative of zinc. The concentration of the promoter is
preferably in the range of from about 1% to about 10~,/o. The inclusion of copper or
copper compounds has proved to be beneficial because it will scavenge lower
concentrations of sulphur compounds and also remove arsine.
In a further preferred feature the shaped desulphurisation agent is porous. The pore
volume will be in the range of 0.1 to 0.6 ml/g, preferably 0.25-0.45 ml/g. It is
recognised that the shaped porous materials should exhibit a significant level of macro
porosity.
The desulphurisation agent may be used in a fixed bed, a fluid bed or a moving bed.
The choice of the reactor system will depend on generated requirements and the nature
of the gas stream, e.g. sour feed. Particle sizes of about 3 to about 6mm are
particularly useful in a fixed bed. In a fluid bed, the particle size is preferably in the
AMEN~D SHEET
,.,.,, IPE~!,EP ..........
CA 022664~8 1999-03-19
range about 20 to about 120 microns, most preferably about 30 to about 100 microns.
For the moving bed, the particle size is preferably in the range about 120 to 600
microns, most preferably about 200 to about 500 microns.
The method of the invention may be enhanced by the incorporation of materials with
sorption properties. Such materials may be added according to the physical form of the
desulphurisation agent. They may be added on to the surface or within the pores of a
porous desulph~lrisation agent or in the bulk phase. Such materials may be catalytica!ly
active. The materials (which may be included either singly or in combination) are
preferably oxides, carbonates, silicates, phosphates of alkali metals, alkaline earths, rare
earths. Zn, Co~ Ni, Mo, Cr, Cu, Ti, Zr, Si, Al, precious metals. The materials may be
incorporated ~ ithin the material of the invention by impregnation, deposition,
coformillg~ precipitation techniques well known to those skilled in the art of catalyst
preparation. The content of the sorption materials may range from about 0.5 to 40% by
weight, preferably in the range 2 to 20% by weight.
In a preferred feature of the invention, other reagents are associated with the
desulphurisation agent to ~eact with other substances present in the stream to be
~reated al from about ambient to about 250~C. One such reagent is an alkaline reagent
such as alkali metal hydroxide or silicate, the alkali metal is preferably sodium. Such an
alkaline reagent will react with halides or strongly acidic gases present in the sour
feed such as SOx to form halide or sulphite respectively (which may be recovered
later). Tlle reagents may be impregnated into the desulphurisation agent or
A~EN5~0 SHEET
~ IPE~/EP
CA 022664~8 1999-03-19
'
incorporated into the bulk phase by other means well known to those skilled in the art of
catalyst preparation.
The spent desuJphurisation agent of the invention may be regenerated by exposure to
an oxidising atmosphere e.g. air at elevated temperature. The presence of steam when
regenerating may be beneficial.
In another aspect the method of the present invention includes the further step of
exposing the spent agent to oxidation at elevated temperature to remove the sulphur
compounds and regenerate the agent for re-use.
The sulphur compound to be removed may be hydrogen sulphide gas or a low
rnolecular weight mercaptan such as propyl mercaptan. The hydrocarbon stream may
be liquid or gas or both, examples being natural gas, town gas, industrial waste gas,
coke oven gas, coal gas, liquid or gas from petroleum plant oil refinery. EMuent
streams from biomass digesters, general industrial process may also be treated.
The method may be perforrned at pressures ranging from about atmospheric to about
100 atmospheres without adverse effect.
In another aspect the invention provides a desulphurisation agent comprising a porous
carrier containing at least one compound of manganese and at least one of iron, present
in relative molar proportions of about 8:1 to 1:8, bonded together by a bonding agent. In
a further aspect the invention
AMEN~D SHEET
IPEAJEP
,. . ... ...
CA 02266458 1999-03-19
WO 98/17374 5 PCTtGB97/02735
provides such an agent incorporating a promoter and in yet a further aspect the
invention provides such an agent incorporating a sorption material.
In order that the invention may be well understood it will now be described by way of
illustration with reference to the following example.
Example I
Pellets of varying composition, as det~ilP~ below, were prepared by standard forming
techniques, calcin~d at 4500C and allowed to cool.
Component, Wt.% A B C D
m~n~nese dioxide 5 38
iron oxide 80 70 70 10
sodium hydroxide 10 5 2
binder 20 20 20 20
30 ml. of each sample were placed in a tubular reactor subjected to a flow (3
litres/hour) of nitrogen cont~ining 20% hydrogen sulphide at ambient ternperature and
~res~ule and the time noted for 10 ppm hydrogen sulphide to be ~letecte i at the outlet
of the reactor. The following results were obtained.
Sample time mins
A 62
B 74
C 92
D 330
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WO 98/17374 PCT/GB97102735
It will be observed that when both Mn and Fe were present the time increased and that
this increase was greatly improved when more m~n~nese was present.
