Process for reducing content of sulphur compounds and poly-aromatic hydrocarbons in a hydrocarbon feed

a technology of polyaromatic hydrocarbons and hydrocarbon feeds, which is applied in the treatment of hydrocarbon oils, liquid carbonaceous fuels, metal/metal-oxide/metal-hydroxide catalysts, etc., can solve the problems of increasing the propensity of catalyst coke making, reducing the yield of valuable products, and high cost, so as to reduce the amount of sulphur in the spent catalyst, reduce the amount of sulphur, and reduce the effect of sox emissions

Inactive Publication Date: 2005-06-23
ZEUTHEN PER +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

[0022] By the inventive process, a low PAH content is achieved in FCC feeds with only slight additional investment in reactor volume and without reduction in run length. The essences of the inventive process consists of cooling the effluent exiting the hydrotreating reactor and passing the cooled product through a small posttreat reactor containing a suitable catalyst. The PAH content of the product existing in the hydrotreating reactor is reduced in the posttreatment reactor owing to the more favourable equilibrium conditions at the lower temperature. Consequently, the end of run temperature in the main hydrotreating reactor is not limited by the PAH content of the product exiting the main reactor, and a small overall reactor volume (main hydrotreater plus post treat reactor) is required for a given run length. In another embodiment of the process, the final bed of the main hydrotreating reactor is operated at lower temperature instead of using a post treatment reactor. The process can be used to lower the content of poly-aromatic hydrocarbons and thereby improve the performance of the FCC unit because of improved crackability of the FCC feed as well as the FCC product qualities.

Problems solved by technology

Nitrogen compounds poison the active sites in the FCC catalyst and increase coke-making propensity of the catalyst and reduce the yield of valuable products.
A shorter run length means high costs due to a higher rate of catalyst replacement, and relative more downtime (i.e. time off-stream) for catalyst change-out with a resultant loss of revenue due to reduced production of high quality FCC gasoline products.
The reactions are reversible and at high reaction temperatures and low hydrogen pressure the conversion of the PAH compounds is thermodynamically limited by equilibrium.

Method used

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  • Process for reducing content of sulphur compounds and poly-aromatic hydrocarbons in a hydrocarbon feed

Examples

Experimental program
Comparison scheme
Effect test

example 1

[0031] Feedstock A (Table 1) was hydrotreated in a semi-adiabatic pilot plant unit running with an outlet temperature of 405° C.—a temperature, which normally is considered as end of run temperature (EOR) conditions and LHSV at 1 (hr−1). The pressure was 50 bar. Pure hydrogen was used as gas. Feedstock A is a mixture of 50% cooker gas oil and 50% straight run vacuum gas oil (SR VGO). Feedstock B (Table 1) was hydrotreated at typical FCC pretreatment conditions in a pilot plant unit at temperature at 400° C. (inlet)-420° C. (outlet) temperature, which normally is considered as end of run conditions at LHSV at 1.7 (h−1). The pressure was 50 bar. The feedstock was a pure cracked VGO.

TABLE 1Properties of feedstock used in the following Examples:PropertiesFeedstock AFeedstock BSG 60 / 600.92790.9924S (wt %)1.343.53N (wt ppm)26773594Aromatics (wt %)Mono-17.78.36Di-9.97.29Tri-11.436.5

[0032] Product properties from both of the tests are shown in Table 2.

TABLE 2Properties of products in Ex...

example 2

[0035] Product A from Example 1 is further hydrotreated at lower temperatures at high LHSV. The pressure is 50 bar, which is identical to the pressure at which product A was obtained.

[0036] A Ni—Mo on alumina catalyst is used in this test. The results are shown in Table 3.

TABLE 3Properties of products in Example 2:Tem-Di-Tri-pera-Naro-aro-tureLHSVSGS(wtmaticsmaticsPAH(° C.)(h−1)60 / 60(wt %)ppm)(wt %)(wt %)(wt %)32560.89140.00385054.65.09.635060.89110.00294684.94.99.5

[0037] As illustrated from the Table 3 there are a remarkable sulphur and nitrogen removal in this low temperature hydrotreatment, and further it is quite obvious that a large amount of the PAH can be removed at a relatively high LHSV during this low temperature posttreatment. Both the sulphur removal and the PAH removal is due to the shift in equilibrium.

example 3

[0038] Product B from Example 1 is further hydrotreated at lower temperatures at different LHSV and temperatures. The pressure is 50 bar, which is identical to the pressure at which product B was obtained. A Ni—Mo on alumina catalyst is also used in this test. The results are shown in Table 4.

TABLE 4Properties of products in Example 3:Tem-Di-Tri-pera-Naro-aro-tureLHSVSGS(wtmaticsmaticsPAH(° C.)(h−1)60 / 60(wt %)ppm)(wt %)(wt %)(wt %)30020.93690.150020587.720.127.830040.93900.1588206710.221.331.530060.94060.161820809.921.431.635020.93350.104916576.617.023.635040.93650.131718709.218.127.335060.93780.144218779.619.328.9

[0039] Again it is clear that a large amount of the poly-aromatic compounds can be removed at low temperature (and the same pressure) due to the shift in equilibrium. Again there is a significant and important sulphur removal at this low-temperature hydrotreatment.

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Abstract

A process for reducing content of sulphur compounds and polyaromatic hydrocarbons in a hydrocarbon feed having a boiling range between 200° C. and 600° C. is disclosed. The process comprises in combination contacting the feed and hydrogen over a hydrotreating catalyst and hydrotreating feed at hydrotreating conditions, cooling the hydrotreated effluent and hydrogen-rich gas from the hydrotreating reactor and contacting the effluent and hydrogen gas over a hydrotreating catalyst in a post-pretreatment reactor at a temperature sufficient to lower the polyaromatic hydrocarbon content.

Description

BACKGROUND OF THE INVENTION [0001] The present invention relates to a process for removal of sulphur and polyaromatic compounds in vacuum gas oil by hydrotreatment of FCC hydrocarbon feed stock. [0002] Many countries are tightening specifications for the sulphur content in diesel and gasoline fuels. The fluid catalytic cracking (FCC) units are a major source of gasoline, but also the major source of sulphur in gasoline and diesel fuels. Lower sulphur content in fuel requests either treating the FCC feed or treating its products. [0003] Treating the FCC products involves multiple process solutions: naphtha treating, light-cycle oil (LCO) treating and flue gas treating to control the SOX emissions. Treating feed to the FCC unit can increase yields and at the same time lower sulphur levels in gasoline, and diesel fuels and reduces SOX emissions. The increased conversion in the FCC unit resulting from feed treatment may improve refinery margins. Product treatment, however, offers no yie...

Claims

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Application Information

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Patent Type & Authority Applications(United States)
IPC IPC(8): C10G45/02B01J23/88C10G45/50C10G65/04C10G65/08C10L1/00C10L1/08
CPCC10G65/08C10G65/043
Inventor ZEUTHEN, PERCOOPER, BARRY H.
Owner ZEUTHEN PER
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