CA2021296A1 - Process for removing carbonyl-sulfide from liquid hydrocarbon feedstocks - Google Patents

Abstract

ABSTRACT
The present invention relates to a process for removing carbonyl sulfide from a liquid hydrocarbon feedstock, said process comprising the steps of (a) passing said hydrocarbon feedstock over an absorbent material comprising nickel deposited on a support material wherein nickel is present as both nickel oxide and metallic nickel and wherein the absorbent material has been conditioned by passing an inert gas flow containing a minor amount of propylene; and (b) recovering a liquid hydrocarbon stream having a substantially reduced carbonyl sulfide content.

Description

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PROCESS FOR REMO~rING CARBO~YL-SULFID~ PROM LIOUID
HYDROCARBON EEEDSTOCKS
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~IELD OF THE INVENTION

The present invention relates to a process for removing sulfur, present in the form of carbon oxysulfide or carbonyl sulfide, from liguid hydrocarbons. ~,ore particularly, ~he present invention relates to a process 5 for the removal of carbonyl sulfide from hydrocarbon feedstocks containing propylene and to the conditionin~ of .he absorbent material use~ in the process.
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~ACKGROUND OF THE INVE~TION

Industrial applications of liquid hydrocarbons and O particularly, liquified olefinic hydrocarbons, have become more increasingly specialized. The technolo~y as presen.ly developed utilizes highly efficient ca~alysts to convert these liquified hydrocarbon feedstocks into final product such as polymers. ~owever, these highly efficient 5 ~atalysts are very sensitive to contaminants, particularly 4~ ur contaminants, found in these hydrocarbon feeds~ocks.
In aadi.ion to the well known sulfur compounds such 2s hydro~en sul.~ide and mercaptans, the hydrocarbon feedtocks normally contain a small quantity of carbonyl sul ide (COS).
O Usu.~lly COS is present to the extent of only several hundred parts per million (ppm) by weight. However, even this small amount is normally beyond the allowable limits of an acceptable product. Since carbonyl sulfide is almost always formed when carbon, oxygen, and sulfur or their S compounds, such as carbon monoxide, carbon disulfide and the like, are brough~ to~ether at high temperatures, this compound is most freouently found in the hydrocarbon . .

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eedstocks resulting from thermal and/or catalytic cracking operationsl although, in some cases, it has been found in virgin petroleum fractions.
To some extent, carbonyl sulfide is not as reacti~e as its companion in hydrocarbons, hydrogen sulfide. According to Rirk-Othmer's Encyclopedia of Chemical Technoloay, Vol.
`13, pages 384-386, 1954 edition, carbonyl sulfide reacts slowly with the aqueous alkalimetal hydroxides and is only slowly hydrolyzed to carbon dioxide and hydrogen sulfide.
) This rel2~ively unreactive characteristic of carbonyl sulfide makes it extr~mely~difficult to remove from petroleum streams by conventio-nal desul~urization techniques.
The presence of COS, even at very low concentrations, oftentimes renders olefins valueless ~or many purposes.
For example, high purity olefins are reguired for the satisfactor~ production of many polymeric products, especially those useful ,~s plastics, including polymers of ethylene, propylene, and the like. As a result, there has O b~n a real need to improve techniques for removing COS
~rom hydrocarbons, especially those used for polymer produc~ion.
Some of the known methods for removing carbon oxysulfide (COS) from hydrocarbon streams include the ~5 following. In British Patent Specification No. 1,142,339, published February 5, 1969, the inventors teach a process for the removal of COS from gas mixtures in which unsaturated compounds such as propyne and propadiene are present, comprising p2ssing said mixtures in liquid phase 30 at atmospheric or superatmospheric pressures over a subs.ance which contains one or more of the oxides of cadmium, zinc, nickel or cobalt supported on a carrier. It is stated that this process re~uces the CO5 concentration to less than one (1) ppm.
U.S. Patent No. 4,290,879 to Woodall et al, teaches ~e remo~21 of carbonyl sulfide from propane and other . .... ....
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similar liq~ified petrole~m gas products by mixing liguidmethanol with the untreated liquified gas and subsequently contacting the liquid mixture with solid potassium hydroxide. The COS concentration is reduced to less than , one (1) ppm by volume ~ .S. Patent No. 3,315,003 ~o ~C)lelgha~1an, t~che~ ~hAt carbonyl sulfide can be effectively removed from normally gaseous hydrocarbons by first liquifying the hydrocarbons and then contacting them with soda-lime. The effluent gas must subsequently be dried to remove the moisture therefrom.
~ .S. Patent No. 3,284,531 to Shaw et al, teaches that COS can be removed by passing a fluid hydrocarbon through a bed of a n anhydrous, weakly basic, anion exchange resin.
.S. Patent No. 3,282,831 to ~amm, discloses a method for removing CoS from a hydrocarb~n stream by utilizing an .anionic exchange resin which is in the hydroxyl cycle and which is not fully hydrated.
The problems in purifying propylene and 'he like 3 olefins are sin~ularly complicated by the nearly identical ~iling points o8 propylene and COS which makes COS removal by frac'ionation unsuitable. As a result, the levels of COS impurity in propylene stocks are often times intolerably high.
Still other disadvantages are encountered in the heretofore known procedures for the removal of COS ~rom hydrocarbons, particularly those to be used for olefin polymerization. For example, some of the established methods introduce water or other contaminants into the 0 hydrocarbon stream, all of which must be removed by additional processing in order to place the hydrocarbon in suitable condition for use. Any such additional processing, as well as any requirement to employ elevated temperatures adds materially and undesirably to the cost of :5 the operation.
None of the above me~hods can reduce the COS content .... . . . . .....

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Accordingly, it can be seen that there ls a need for a process to reduce the COS concentration in a hydrocarbon stream to 50 ppb by weight or lower.
S~MMARY OF THE INVENTION
The present invention is dlrected to a process for the removal of carbonyl sulfide from hydrocarbon feedstocks, and more particularly from olefinlc hydrocarbon feedstocks containing propylene and from about 1 to 10 ppm by weight of COS. In accordance with the present invention, COS 1s rPmoved by passlng the hydrocarbon feed over a condltioned absorbent material preferably comprislng nickel depos~ed on a support materlal.
DETAILED DESCRIPTION-OF THE PREFERRED EMBODIMENTS
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The present invention relates to the removal of carbonyl sulfide (~OS), sometlmes referred to as carbon oxysulfide, from liquid hydrocarbon streams. of partlcular interest is the treatment of llquid hydrocarbon streams containing oleflns which streams are to be subsequently sub;ected to polymerization using polymerization catalysts. AS stated prevlously, hydrocarbon streams containing propylene present a special problem for rempval of COS by fractionation because of the nearly identical boiling points of propylene and COS. The present invention ls, therefore, particularly useful for COS removal from hydrocarbon streams containing propylene.
The subsequent dlscusslon will describe the inventlon ln terms of treating ll~uld hydrocarbon feedstocks which essentially contaln a ma~or amount of propylene and minor amounts of propane and lmpurities such as COS. It should, however, be understood that the present invention is appllcable to the treatment of liquld hydrocarbon streams ln general and oleflnlc liquld hydrocabon streams ln general and oleflnlc llquid hydrocabon streams ln partlcular, l.e., hydrocarbon streams containlng ethylene, propylene, butenes or any combinat.ion thereof since these olefins wlll react like propylene when contacted wlth the absorbent material.
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It has been found that propylene absorbs onto th~
absorbent material when contacted with the hydrocarbon feedstocks containing propylene during the COS removal from said feedstocks and that the propylene absorption reaction , is exothermic, occurring to a~greater extent during start up. Under certain conditions, the termperature ri~e durinq propylene absorption may be very important, more particularly a~ the surface of the material of which the temperature may be much higher than that measured with a O thermocouple r and it may thus damage the absorbent material.
In addition the hig~ temperatures cause undesired side-reactions, more particularly propylene dimerization and trimerization. The dimers are hexenes which copolymerize with propylene and break the regularity of the linear chain of isos~atic propylene. As a result, the copolymer has a lower cristallini.y than polypropylene, and thus a lower melting point; its mechanical resistance is also lower.
~ ' The Applicants have found that an excessive increase 'O ~ the temperature of the absorbent material can be avoided by concitioning the material with a minsr amount of ~he hyàrocarbon to be treated. ~en the hydrocarbon feedstoc~
contains propylene the conditioning comprises passing over the materi21 an inert gas flow containing a minor amount of 25 propylene.
The conditioning is conducted for a time at sufficient temperature and pressure under the inert gas flow, containing the rninor amount o propylene, to condition the ~bsorbent material without causing an excessive increase in 30 temperature of said absorbent material.
The inert g2s, used in the conditioning step is generally nitrogen. It is important that the inert gas does not contain oxygen, or contains the least possible amount of oxygen, preferably less than 10 ppm.
The propylene contained in the inert gas flow of the conditlonlnq step can be pure propylene, but most often a 2Sr~i - ~ -mlnor amount of propylene in gaseous form ls taken from the propylene feed that is to be treated to remove COS. This propylene feed is polymer grade propylene that contalns the small amount of COS.
It is preferable to begln the conditloning procedure by passlng essentially pure lnert gas over the absorbent material, before lntroducing a minor amount of propylene 1n the inert gas flow. The propylene concentration in the inert gas flow preferably ranges from about 0.1 to 5 vol ~, more preferably absut 0.5 to 2 vol ~, with about 1 vol % belng most preferred.
The conditionlng step is preferably carrled out at about atmospherlc pressure at or below ambient temperature preferably below about 15C. The copdltioning step is continued until the propylene concentration at the outlet equals that introduced indicating that the absorption reaction ls complete. It ls also possible to monltor the conditloning step by the passage of an exotherm, shown by thermocouples introduced wlthln the absorbent material.
It is known that, when the absorbent material is prepared ex situ and stored under a non-oxidizlng atmosphere (usually stabllized under CO2), the traces of oxygen usually present thereln have a negatlve effect on the propertles of the absorbent ma~erlal. This negative effect can be remedled if, before the above-mentloned conditionlng step, the stored absorbent materlal ls pretreated by passlng a gaseous flow over sald materlal, at a temperature between about 150 to 250C; preferably at about atmospherlc pressure. The gaseous flow can be entirely inert, however, lt ls preferred that the gaseous flow at first be inert followed by a mixture of an inert gas and hydrogen wherein the hydrogen conentration is gradually increased from 1 to more than 95 vol %.
As above, the inert gas used in the pretreatment ls generally nltrogen. In the pretreatment it is also important that the lnert gas does not contain oxygen, or contains the least posslble amount of oxygen, preferably less than 10 ppm.

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In the pretreatment the inert gas flow is contin~ed, prior to the introd~c~ion of hydrogen, until the concentration of the non-oxidizing gas at the o~tlet is sufficiently low (e.~. lower than 0.1 vol ~). When said 5 non-oxidizing gas is carbon dioxide, two small exothermal endothermic temperature variations may be observed d~ring the pretreatment. Each endotherm being associated with a rapid increase of Co2 conentration in the vent gas.
Hydrogen is then introd~ced, first at a concentration of 10 about 1 vol % in the inert gas flow, then at concentrations gradually incresing to over 95`vol ~ while meas~ring the bed temperature which should not be allowed to rise above 300C, preferably not above 250C.
Following hydrogen pretreatment, ~he absorbent 15 material is cooled under hydrogen flow to ambient temperature, purged free of hydrogen ~ith an inert gas flow, then condition according to the above conditioning proced~re.
The COS removal process of the present invention '0 red,uces the COS concentration in the treated hydrocarbon ~edstock to 50 parts per billion by weight (ppb) or lower.
The original COS concentration may be as hi~h 2S 1000 parts per million by weight (ppm) or higher depending on the process of making and the origin of the hydrocarbon ~5 feedstock. Due to the expense and specialization of the present invention, it is preferrd to utilize other less costly and less complex processes to reduce the COS
concentration to 70 ppm or less prior to treatment with the absorbent of the present invention.
While the subseq~ent discussion and examples may describe the absorbent material as a nickel absorbent material, the nickel absorbent material is only preferred and should not limit the reasonable scope of the present invention. It is envisioned that the pretreatment and 35 conditioning of the present invention would be useful for '~

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treating any absorbent material that has an excessive increase in temperature, during COS removal, tha~ could cause side-reactions and~or damage to the abs~rbent material.
The absorbe"t material of the present invention preferably comprises nickel deposited on a support material.
Silica, silico-aluminas, alumina, kieselguhr and other similar materials can be utilized as the support. When nickel is used the nickel is preferably present both as ;0 metallic nickel and as nickel oxide. The metallic nickel should constitute from about~35 to about 70 wt.~ of the total nickel. Preferèàbly the absorbent comprises from about 40 to about 70 w~.% total nickel and from about 30 to about 60 wt.% support material.
The nickel can be deposited on the support by any of the several methods well known to those skilled in the art.
For example, nickel can be depositd on the support by dissolving nickel nitrate in water, mixing the solution wi.h the support and precipitating the nickel, for example 20 in the form of nickel carbonate, and subseauently washing, ~rying and calcining the precipitate. The nickel deposited in this manner is then partially reduced by means of hydrogen to form metallic nickel in a quantity of L rom about 35 to about 70 wt ~ of the total quantity of nickel 25 deposited, the remainder being in the form of nickel oxide.
In general, the size cf the nickel crystallites after reduction is from about 10 to about 200 A-. The size of the nickel crystallites depends on the extent of reduction carried ou~. In fact, if the degree of reduction is 30 increased, the size of the crystallites is increased but the absorbent material obtained does not have the desired properties. On the other hand, if the degree of reduction is too low, the crystallites still have good dimensions but the quantity of nickel available in this case is too small 35 to ensure successful purification of the feedstock.

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g The specific surface area of the absorbent material obtained after reduction is generally be~ween 100 and 200 m2/9 .
The particle size ~f the absorbent material depends 5 especially on the pressure 105s allowed in the reactor; it has been noted, however, that it is advantageous to use the absorbent material in finely divided form. Preferably, the particle size of this material does not exceed about 3.5 mm and is most preferably from about 1 to about 2.5 mm.
0 In utilizing the latest ~eneration of Ziegler-type catalysts in the produGtion of polypropylene, it is essential that the propylene feedstoick contain less than 50 ppb and preferably less than 30 ppb of COS. It has been unexpectedly found that by passing the propylene feedstock 5 over an absorbent material conditioned according to the present invention and consisting essentially of from about 40 to abou, 70 wt.% nickel deposited on support materials selected ,rom the group consisting of silica, ~ilico-alumin2s, alumina, kieselguhr and similar materials, ~o w~e~ein the nickel is present bo~h as metallic nickel and .. as nickel oxide and wherein the metallic nickel represents from about 35 to abou~ 70 w~.~ of the total nickel, the feedstock ob~ained has a COS content no~ exceeding 30 ppb.
This result is unexpected due to the degree of purity '~ obtained and due to the fa~t that this process can be carried out either in the presence or absence o~ water.
In polypropylene production, ~he liquid hydr~carbon feedstock generally comprises more than 75 wt.% propylene, more particularly, from about 85 to about 99 wt.~
30 propylene, and from about 1 to abdut 10 ppm COS. In one embodiment of the presen. inven~ion r the liquid propylene feedstoc~ is passed over the condi.ioned absorbent material at a temperature o from about 0C to abou~ ~O~C and under sufficient pressure to keep the medium in the liquid phase.
35 The liquid hourly space veloclty (LBSV) utilized is from about 0.1 to about 20 and preferably from 0.2 to abo~t 15.

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The examples which follow are given in order to provide a better llustration of the process of the present invention, but without there~y restricting its scope.
Exa~Dle I
5 a. absorbent Material An absorbent material was prepared in situ, comprising 43.3 wt.~ of silica as support, on which nickel was deposited, wherein the nickel i5 present in the forms of 34 wt.% of NiO and of 22.7 wt.~ of metallic nickel.
10Before reduction, the absorbent material contained about 49 wt.~ of nickel ~
The absorbent material was finely divided so as to obtain particles of about 1 mm average dimension.
The specific area of said material was of 145 m2/g.
5 b. Conditlon_na Step A nitrogen flow was passed during 4 hours over the absorbent material, under atmospheric pressure, at a tempera~ure of 20C, and with a g2seous hourly space yelocity (GHSV) of 125 l/l.h. During a further 12 hours, '0 the conditioning W2S continued under the same conditions wlth ni.rogen containing 1 vol % propylene.
c. uri ication of .he Feed A liquid hydrocarbon feedstock conteining 99 vol % of propylene, 1.5 ppm of COS and less than 5 ppm (detection '5 limit) of hexenes, W2S passed on the conditioned absorbent material, at a temperature of 30DC, under a pressure of 1.5 MPa (15 bars) sufficient to maintain the feed in the liquid - phase, and with a liquid hourly space velocity ~LHSV) of 10 l/l.h.
~0After 5 hours, ~he purified feed contained 19 ppb Or C~S and less than 5 ppm ~detection limit) of hexenes.
ExamDle II
An absorbent material w~s prepared according to the procedyre ~escribed in ~xample I.a. ~t was stored under ,5 carbon dioxide during one month.

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The absorbent material was pretreated by passing a gaseous flow thereon, at a ~emperat~re of 180-C and under atmospheric pressure, said g~seous flow being formed first of nitrogen during 14 hours, ~hen of a mixture of nitrogen and hydrogen during a further 24 hours, the hydrogen concentration therein being increased by about 5 vol ~ per ho~r up to more than 95 vol ~. The absorbent material was cooled under said flow of nitrogen and hydrogen, then purged free of hydrogen with a nitrogen flow.
0 The absorbent material was conditioned as described in Example I.b., and the~rification procedure of Example I.c. was repeated with the conditioned material. Results similar to Example I were obtained.
Exam~le III Com~arative !5 Example I W25 repeated with the omission of the conditioning step I.b. After 5 hours, the purified feed 'contained 24 ppb of CoS and 20G ppm of hexenes.
Exam~le IV Com~arative . An absorbent material was prepared as aescribed in 20 ~ample I.a. and stored under carbon dioxide during one month.
- A liGuid hydrocarbon feedstock containing 99~ of propS~lene, 2.7 ppm of COS and less than 5 ppm (detection limit) of hexenes, W2S passed on the absorbent material, at 25 a tempera~ure of 25~C, under a pressure of 1.5 MPa (15 bars) sufficient to keep the feed in the li~uid phase, and with a ~HSV of 5 l/l.h. After 5 hours, the purified feed contained 700 ppb of COS.
Exam~le V
A liguid hydrocarbon feedstock containing 99~ of propylene and having a residual COS content of 2.7 ppm was passed over an absorbent material consisting of 43.3~ by weight of silica as the support, on which nickel was deposited, the nickel being present in the form of NiO to 35 the extent of 34% by weight and in the form of metallic Ni to the e~'ent of 22.7~ by weigh~.

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Before red~ction, the absorbent material contained aboUt 49% by welght nic~el.
The absorbent material was finely divided to give an avera9e particle size of abo~t 1 mm.
The specific s~rface area of this material was 145 m2/g .
The above mentioned feedstock was thus passed over the absorbent material at ambient temperature, at a sufficient press~re to keep the feedstock in the liquid phase (15 ) bars), and at an ~HSV of 5 l/l.h.
The purified feedst~ck had a COS content of 18 ppb.
ExamPle VI
A liq~id hydrocarbon feedstock containing 99 wt.~
propylene and having different resid~al COS content was passed over .he same absorbent material 2s in Example V.
The nickel containing absorbent material had a nickel con-ent of abo~t 49% by weight. The absorbent material was finely divided so as to give an average particle size of a,bou' 1 mm. The specificiarea of this material was abou~
0 145 m2/g.
The feeds~ock w2s pzssed over said nickel containing material under ~arious operating conditions, which zre indicated in Table I.
~ s can be seen from the results, the purified '5 feedstock had a COS content lower than 30 ppb, even when the feed contained water, which is known to be detrimental.
Table I
30 LBSVTemperature B20 Content COS
bed (rC)(ppm) in out P~m PPb .
4.95 20 13 1.8 22 355.05 25 8 4.5 20 4.8 23 8 3.1 1B
9.3 16 14 1.85 15 15.C5 15 14 1.3 24 ~`.~!i ' .
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Example VII
A liquid hydrocarbon feedstock containing 95.6 wt.%
propylene, 3.8 wt.~ prop~ne and 0.6 wt.~ Cq, the water content of whiCh being less than 10 ppm, and having different residual COS content was passed over the same absorbent as described in ~xamples V and VI except that the particies had an average diameter of 3.2 mm. This example is given to illustrate the activity of the catalyst over a long period of time.
The feedstoc~ was passed under a pressure of 14 bar over a bed containing ~liters of a nickel containing a~sorbent material. -The other operating conditions such as LRSV andempera!ure bed are indicated in Table II.
Table II
~Day Temperature LRSV COS
bed (C) in o~t ~m ~b ; . 14 9.4 2.8 25 ~ 9 9.3 1.4 23 12 6 9.7 4.2 21 19 7 9.7 2.55 20 9.7 3.0 11 34 7 9.75 1.9 16 39 2 9.85 1.85 23 52 9 9.6 0.85 20 58 3 10.15 0.8 22 68 11 9.65 2.2 20 82 6 9.75 1.95 15 88 1 9.8 0.8 15 This example shows that even after 88 days the activity of the catalyst remained very high.

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Claims (22)

1. A process for removing carbonyl sulfide from a liquid hydrocarbon, feedstock, said process comprising the steps of:
a) passing an inert gas flow containing a minor amount of at least one hydrocarbon that is also present in said liquid hydrocarbon feedstock over an absorbent material thereby conditioning said absorbent material so as to avoid an excess increase in temperature during hydrocarbon feedstock contacting;
b) passing said liquid hydrocarbon feedstock over the conditioned absorbent material of a) to selectively absorb carbonyl sulfide thereon, and c) recovering a liquid hydrocarbon stream having a substantially reduced carbonyl sulfide content.

2. The process according to Claim 1, wherein said hydrocarbon that is also present in said liquid hydrocarbon feedstock is an olefinic hydrocarbon.

3. The process according to Claim 2, wherein said olefinic hydrocarbon in said inert gas is propylene in a concentration in the range of about 0.1 to 5 vol%.

4. The process according to Claim 3, wherein the inert gas flow contains about 0.5 to 2 vol % propylene.

5. The process according to Claim 4, wherein the inert gas flow contains about 1 vol% propylene.

6. The process according to Claim 1, wherein essentially pure inert gas is passed over said absorbent material prior to the passing of said inert gas flow containing the minor amount of hydrocarbon.

7. The process according to Claim 6, wherein the inert gas is nitrogen.

8. The process according to Claim 1, wherein the absorbent material is pretreated prior to its conditioning comprising first an inert gas, then a mixture of inert gas and hydrogen containing an increasing hydrogen concentration.

9. The process according to Claim 1, wherein said absorbent material is comprised of nickel deposited on a support material wherein said nickel is present as both nickel oxide and metallic nickel.

10. The process according to Claim 9, wherein said absorbent material has a particle size smaller than about 3.5 mm and a specific surface area of about 100 to 200 m2/g.

11. The process according to Claim 10, wherein said absorbent material comprises about 40 to 70 wt. %
total nickel and said metallic nickel represent about 35 to 70 wt. % of the total nickel with the balance being nickel oxide.

12. The process according to claim 11, wherein the support material is selected from the group consisting of silica, silico-aluminas, alumina, kieselguhr, and combinations thereof.

13. A process for removing carbonyl sulfide from a liquid hydrocarbon feedstock, said process comprising the steps of:
a) passing an inert gas flow containing a minor amount of propylene over an absorbent material comprised of nickel deposited on a support material, wherein said nickel is present as both nickel oxide and metallic nickel, thereby conditioning said absorbent material so as to avoid an excess increase in temperature during hydrocarbon feedstock contacting;
b) passing a liquid hydrocarbon feedstock containing propylene over the conditioned absorbent material of a) to selectively absorb carbonyl sulfide thereon, and _ 16 -c) recovering a liquid hydrocarbon stream having a substantially reduced carbonyl sulfide content.

14. The process according to Claim 13, wherein said inert gas flow contains about 0.1 to 5 vol % propylene and liquid hydrocarbon feedstock comprises at least about 75% by weight of propylene.

15. The process according to Claim 14, wherein said inert gas flow contains about 0.5 to 2 vol % propylene and said liquid hydrocarbon feedstock comprises at least about 95% by weight of propylene.

16. The process according to Claim 15, wherein said inert gas flow contains about 1 vol % propylene.

17. The process according to Claim 13, wherein said b) is carried out at a temperature of about 0°C to 90°C, at a sufficient pressure to retain said liquid hydrocarbon feedstock in liquid phase; and at an LSHV of about 0.1 to 20, and wherein the original concentration of the carbonyl sulfide in said liquid hydrocarbon feedstock is about 1 to 70 parts per million by weight.

18. The process according to Claim 13, wherein said absorbent material has a particle size smaller than about 3.5 mm and a specific surface area of about 100 to 200m2/g, and comprises about 40 to 70 weight percent total nickel and the metallic nickel represents about 35 to 70 wt % of the total nickel with the balance being nickel oxide.

19. The process according to Claim 18, wherein the support material is selected from the group consisting silica, silico-aluminas, alumina, kieselguhr, and combinations thereof.

20. A process for removing carbonyl sulfide from a liquid hydrocarbon feedstock, said process comprising the steps of:
a). passing a gaseous flow at a temperature of about 150 to 250°C over an absorbent material comprised of nickel deposited on a support material wherein said nickel is present as both nickel oxide and metallic nickel, wherein said gaseous flow is first an inert gas, then a mixture inert gas and hydrogen thereby pretreating the absorbent material;
b) passing an inert gas flow containing a minor amount of propylene over the pretreated absorbent material of a) thereby conditioning said absorbent material so as to avoid an excess increase in temperature during hydrocarbon feedstock contacting;
c) passing said liquid hydrocarbon feedstock over the conditioned absorbent material of b) to effectively absorb carbonyl sulfide therein; and d) recovering a liquid hydrocarbon stream having a substantially reduced carbonyl sulfide content

21. The process according to Claim 20, wherein the hydrogen of said mixture in said gaseous flow is increased from about 1 to over 95 vol %, and step a) is conducted at about atmospheric pressure

22 The process according to Claim 20, wherein said absorbent material has a particle size smaller than about 3.5mm and a specific surface area of about 100 to 200m2/g, and comprises about 40 to 70 wt % total nickel wherein metallic nickel represent about 35 to 70 wt % of the total nickel, and wherein said hydrocarbon feedstock comprises at least about 75 % by weight of propylene