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Use of a catalyst comprising a beta silicon carbide support in a selective hydrodesulphurization process

a technology of beta silicon carbide and hydrodesulphurization process, which is applied in the field of oil refining industry, can solve the problems of consuming substantial quantities of olefins by catalysts, and affecting the quality of hydrocarbon oil treatment products,

Inactive Publication Date: 2005-03-17
INST FR DU PETROLE
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

[0012] In contrast, the Applicant has surprisingly discovered that for the selective hydrodesulphurization of olefinic feeds, the use of catalysts with a support essentially constituted by β has substantial advantages over known catalysts. It appears that the use of SiC is advantageous as it can produce a catalyst with improved selectivity, and can minimize the start up time for said catalyst by limiting the initial hydrogenating overactivity. Such a problem has been reported for commercial catalysts supported on alumina, and U.S. Pat. No. 4,149,965 teaches prior deactivation of the catalyst prior to its use in hydrotreating an olefinic feed, the deactivation treatment being selected so as to limit the hydrogenating activity of the catalyst.
[0013] Without wishing to be bound to a particular theory, this effect could be considered to derive from the properties of the support, which could be both substantially non acidic and substantially non basic. It is known that the hydrogenating properties of catalysts are enhanced by the acidity of the support. The absence of acidity could contribute to explaining the results obtained, thanks to a relatively low hydrogenating activity of the catalyst with a β SiC support as regards olefins. This could encourage the hydrodesulphurization selectivity as regards olefin hydrogenation. It cannot be excluded that the nature of the sulphide phase and thus its catalytic properties could be different, depending on whether it is formed on an alumina support or on a β silicon carbide support.

Problems solved by technology

However, known prior art catalysts consume quantities of olefins which remain substantial and prejudicial to selling price of the fuel.

Method used

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  • Use of a catalyst comprising a beta silicon carbide support in a selective hydrodesulphurization process

Examples

Experimental program
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Effect test

example 1

Preparation of a Catalyst A for Use in Accordance with the Invention

[0022] A catalyst A was obtained by using a synthesis method termed the OrganoMetallic Surface Chemical method (OMSC). Silicon carbide SiC extrudates (2 mm diameter) were supplied by SICAT Sarl; their principal characteristics are summarized in Table 1.

TABLE 1Characteristics of SiC supportFormSurface area: SBET m2 / gPore volume (Hg) cm3 / gExtrudates530.42 mm

[0023] An aqueous solution of ammonium heptamolybdate was impregnated using the pore volume method into the silicon carbide. The molybdenum (Mo) concentration in the solution was calculated to obtain the desired Mo content on the support, then the solid was left to mature for 12 hours. The solid was then oven dried at 120° C. for twelve hours, and calcined for two hours at 500° C. in a stream of dry air (1 l / h.g of catalyst). The solid was then sulphurized in a stream of gaseous H2S in hydrogen (15% by weight of H2S, total gas flow rate 1 l / h.g of catalyst) from...

example 2

Preparation of a Catalyst B (Comparative)

[0024] Catalyst B was obtained using the same synthesis protocol as for catalyst A, with an industrial alumina type support from Axens. The characteristics of the support are given in Table 3:

TABLE 3Characteristics of industrial alumina supportFormSurface area: SBET m2 / gPore volume (Hg) cm3 / gBeads600.62.4-4 mm

[0025] The characteristics of the catalyst after sulphurization are shown in Table 4:

TABLE 4Characteristics of catalyst B (comparative)Mo contentCo contentCo / (Co + Mo) atomic ratio(wt %)(wt %)(atom / atom)3.20.70.36

[0026] Thus, catalyst B is essentially distinguished from catalyst A in the nature of the support used, and also by the dimensions of the grains.

example 3

Comparison of Use of Catalyst A with that of Catalyst B on a First Olefinic Feed

[0027] In order to overcome diffusional limitation problems, the catalysts were ground to the 300-500 micrometre fraction in the absence of air. The solids were then passivated in air at ambient temperature for 4 hours and loaded into the catalytic reactor. The catalyst was then sulphurized in situ using a synthetic feed (6% by weight of dimethyldisulphide in n-heptane) under the following conditions: Total pressure=2.0 MPa, H2 / feed=300 (litre / litre), mass flow rate of feed with respect to catalyst per hour (WHSV)=3 h−1. A constant temperature stage for sulphurization was carried out for 4 hours at 350° C. (temperature ramp-up 20° C. / hour). After sulphurization, the temperature was reduced to 150° C. and the sulphurization feed was replaced with FCC gasoline to be treated, and the operating conditions were adjusted. In this example, the two catalysts were tested on a first olefinic feed constituted by a...

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Abstract

The invention concerns the use of supported catalysts comprising at least one metal or metallic compound of a metal from group VI and / or group VIII deposited on a support essentially constituted by β silicon carbide in a process for selective hydrodesulphurization of an olefinic hydrocarbon feed that is substantially free of polynuclear aromatics and metals. The invention can be used to carry out deep desulphurization of catalytically cracked gasoline cuts with very limited saturation of olefins and thus a minimum loss of octane number.

Description

FIELD OF THE INVENTION [0001] The present invention relates to the oil refining industry, more particularly to the production of gasoline bases from different units for converting oil cuts, in particular cracking units. [0002] Thermal cracking units, for example for visbreaking or cokefaction, or catalytic cracking, for example for fluidized bed catalytic cracking, produce unsaturated gasoline cuts comprising large quantities of aromatics and olefins. Such gasoline cuts generally have substantial levels of sulphur, for example in the range 200 to 3000 ppm by weight, which is incompatible with general specifications for gasoline fuel. Thus, such cuts have to be deeply desulphurized to reduce the sulphur content to less than 30 ppm by weight or even 10 ppm by weight in accordance with current specifications, or to satisfy future specifications. Industrial processes that are in current use to carry out said operation are catalytic hydrodesulphurization processes. [0003] Said cuts typic...

Claims

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Application Information

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IPC IPC(8): B01J23/24B01J23/74B01J23/85B01J23/882B01J27/224B01J32/00B01J35/10B01J37/02B01J37/20C10G45/06C10G45/08C10G45/10
CPCB01J23/24C10G2300/301B01J23/85B01J23/882B01J27/224B01J37/0203B01J37/0205B01J37/20C10G45/06C10G45/10C10G2400/02C10G2300/104C10G2300/1044C10G2300/202B01J23/74
Inventor BOUCHY, CHRISTOPHEDIEHL, FABRICE
Owner INST FR DU PETROLE