GB2408746A - Blended naphtha and process for production thereof - Google Patents

Abstract

A blended naphtha comprises: <SL> <LI>a) an olefinic naphtha comprising 10-80 wt % olefins, 20-90 wt % non-olefins, wherein the non-olefins comprise > 50 wt % paraffins; and <LI>b) a naphtha selected from hydrotreated or hydrocracked Fischer-Tropsch naphtha, <LI>hydrotreated or hydrocracked petroleum naphtha or mixtures thereof. </SL> Also disclosed is a process for producing a blended naphtha from the components above, wherein the blend comprises < 10ppm sulphur, and has an acid number < 1.5. A further disclosure relates to a process for producing blended naphtha comprising, <SL> <LI>i) converting hydrocarbon asset gas to syngas; <LI>ii) converting said syngas to hydrocarbons in a Fischer-Tropsch reactor; <LI>iii) isolating an olefinic naphtha having a composition as in (a) above; <LI>iv) mixing the olefinic naphtha with a naphtha selected from the group as in (b) above. </SL>

Description

IIigh Purity Olefinic Naphthas for the Production of Etllylenc and

l'ropylcne ( ROSS-RET ATE O APPl l(lATIONS 1 he present alplcatoi Is related to l.J.S l'atent Application No lO/355 11 () (Docket No ()059S()-X24) ent(led 111 T'irrty Olefnc Naplitlas for thc l'roclctor of Lilylcc and l'ropylee and IJ S P atent INPP1;Cat[On NO. 10/354,')57 (DOCket NO. 0()5').S()-825) CntitlCd I lily T:'urty Olellnc Napltlas for (hc Production ol P.tlylenc and l'ropyleic both of wl,cl are flecl 1erewtl 11111 I) ()I I HE INV}ilNTION ThI.s InVcHtion rc]ates t;:' nprovcd technicTnes for pi-oclccng lo\ver olcilis fron ht,h purty oleQnc naplitlas More speclrcally, tile InvCnticnI relates to a process for converting an rexpensve 1ydrocarbon resorrce fron1 a renote locaton nto hgh purty olefinc naphtlia, transportng lhe olef inc naplilla to a second f'aclty, ancl suhseclrently processng thc oleOnrc ap]ltha to produce IONVCa oletins.

13A(.I<GROUND OF'rHE INVEN'IION Lower olefins, n particular olefins 1aving fion 2 to 4 carbor1 atoms, are sutable startng materials n a larg, e nuniber oL'clemical processes, meluding, I'or example, alkylaton, olgornerzation, and polymerzaton processes The preparaton of lower olefins f'rom a hydroearhon f'eed by crackZg of thal f'eed rs a well- known process and s comnercally ayplied at a large number of petrochemcal nanufactunng facltcs 'I'ypically, a dstllate fi-acton of a crude oil, commonly a naphtlla fracton of thc crude ol, is used as the lydrocarbon f'eed in a napUtha cracker process to produce ethylene.

I;or conmercial reasons, there s a demand for a naplltha crachng process havin, a hrgh selectvity for lower olefins, n1 particular ethylene. '['here s alsc-, a:Ienand to manufacture ethylene fron1 hydrocarhon assets otller tharl petroleun napUtllas, especrally ones that cost Iess and are rnorc aDwldant Examples of sucl1 hydrocarbon assets include natural gas, coal, and heavy oils found n aLunilant supply rn locatorls that are renote from thc ethylene markets. Currerltly there are two approaches to convertng reniote hydrocarbon assets rnto ethylene where the etlylene s manufactured in developed locatrons The first approach Is to convert a hydrocarbon asset obtained at a remote site into a highly paraffinic feed by a Fischer-Tropscl1 process. This approach involves converthlg the hydrocarbon asset into synthesis gas by partial oxidation and converting the synthesis gas Into a mixture of hydrocarbons by a Fischer-Tropsch process. A hydrocarbon fraction from the Fiscller- Tropscll process may be used as a feed to a naphtha cracking process to produce ethylene. By way of exanplc, European Patent Application No. lG1705 discloses that a fraction of the product of a 1;ischer-Tropsc]1 synthesis process may be used as a hydrocarbon feed In a naphtha cracking process. EP 161705 discloses using a Ceil fraction frown the Fscher- 'l'ropsch process, wherein the C j9 fraction substantially consists of hnear paraffins, as a feed for a naphtha cracking process EP 1 l 705 further discloses that by using this feed, tlc sclectvty toward lower o] efins Is increased compared with a naphtha fraction of a crude of].

I'o increase the selectivity of the naphtha cracking process, a hilly parat'finc Fscher Tropsch na.plltha that has been processed.sng hydrogen, mcludng hydrotreatng, hydrocrackng, and hydroisoncnzaton Is typically used. 'l'o produce the ethylene, the highly paraffinc Fscher-'l'ropscl1 naphtha Is typically shipped from the site where synthesz.ed to a developed site anti converted into ethylene in a naphtha cracker.

By way of'cxample, "Performance of the SASOL Sl'D Naphtha as Steam Cracking Feedstock", by Luis P. Dancuart, et a]., ACS 2002 National Mcethg, Boston Mass, August 18 22, 2002, ACS Preprints July 20()2, and U.S. Patent No. 5,371,308 describe examples of this approach. U.S. Patent No. 5,371,308 teaches a process for preparing lower olefins from a hydrocarbons feed comprising a hydroprocessed synthetic oh fraction, wherein the hydrocarbon feed comprising the hydroproccssed syntlletc oil fraction is cracked. '1'he hydroprocessed synthetic oil fraction is derived from a synthesis process, such as a Fischer-Tropsch synthesis process and is subsequently treated m a process In the presence of hydrogen.

The second approach for converting a remote hydrocarbon asset Into ethylene involves the production of methanol This approach involves converting the hydrocarbon asset obtained at a remote site Into synthesis gas by partial oxidation and converting the synthesis gas in a methanol synthesis plant mto methanol. The methanol is typically shipped to a developed site and converted Into ethylene by a Methanol-to-Olefins process. The methanol to oleEns process uses a molecular sieve to dehydrate and convert the methanol to a mixture of ethylene, propylene and other olefins.

There are advantages to usmg the process nvolvmg Fiseher-Tropsch naphtha to produce ethylene n1 comparison to the methanol process These advantages include that the process nvolvmg Fscher-'L'ropsch naphtha can use existing conventional naphtha crackers.

Also, the highly paraf'(inc naphtha produced In this process consists of a mixture of nonnal and So-paraffins with few eyelid compounds (aromatics and naphthenes). This highly paraffinc naphtha provides higher yields of ethylene and lower coking rates than typical petroleum naphthas.

However, there are certain disadvantages of the process involving use of Fischer I'ropsch naplltha. The disadvantages Include the high cost of eonvertmg methane into highly paraffimc naphtha. One element of this higl1 cost is the hydrogen that is typically needed to hydrotreat the Fscher-Tropsell products to provide the highly paraffinc naphtha. In addition, the ethylene cracking step Involves a high temperature endothenne reaction to dehydrogenate and crack the naphtha Into smaller fragments. 'this Ogle temperature endothermic reaction require the USC of a significant amount of costly i'uel.

The approach involving methanol synthesis may require fewer steps, but in genera] the economics of methanol production from natural gas are poor. In addition, when methanol is shipped, it nest he remembered that approximately 50 wt% of the methanol is converted mto water during the Methano]-to-Olefns step. Thus, approximately twice the amount of methanol must be shipped in comparison to a paral'linic naphtha. Furthermore, since methanol is toxic, it is typically shipped in small specialty tankers at higher costs than those needed for parai:'linie naphthas. Finally, this approach requires the construction of new facilities for the Methanol-to-Olefins step.

There is a demand for eeonomiea] and effluent processes to convert inexpensive hydrocarbor assets (SUCH as methane or coa] Tom remote sites) to ethylene in developed locations. It Is desired that these processes have certain advantages. It is desired that the mitral conversion of the hydrocarbon asset to the feed for the naphtha cracker be economical.

It Is desirable that the feed give high yields of ethylene thus requiring a smaller amount of feed mitia]]y. It is desirable that the naphtha cracking step have low operating costs It Is desirable that the overall process be compatible with existing facilities, mcludmg, t'or example, ships, tanks, pUnipS, naphtha crackers, ete.

SUMMARY ()F THE INVENTION

The present Invention relates to tecllques for producing lower olefins from high purity olcfnic naphthas. In one aspect the present invention relates to a process for producing lower olcI;ns. 'lithe process comprises converting at least a portion of a hydrocarbon asset to synthesis gas, and converting at least a portion of the synthesis gas to an olefinic naphtha by a l;scher-rlropsch process. At least a portion of the oleDmc naphtha Is converted m a naphtha cracker to a product stream comprising lower olcfns, and at least a portion of the low olefins front the produce strcan1 of the naphtha cracker arc r ccovered.

In another aspect the present invention relates to a process for producing ethylene. The process coniprses converting at least a portion of a hydrocarbon asset to synthesis gas, and convertng at Icast a portion of the syntlless gas to a hydrocarbon stream in a Fscher-Tropsch process unit. An olelinic naphtha from the hydrocarbon stream is isolated, wherem the olefinc naphtha comprises 25 to 80 weight % olefns and 20 to 75 weight XO non-olefins, wherein the non-olchns conprse greater than 75 weight % paraffins. The olefinic napl1tlla is punfe1 In the presence of a metal oxide to provide a punficd oleEmc naphtha having a total acid number of lest. than 1.5, and at least a portion of the purified oleUn1c naphtha is converted in a naphtha cracker to a product stream comprising ethylene. At Icast a portion of the ethylene from the product stream of the naphtha cracker is recovered.

In a further aspect, the present invention relates to a process for manufacturing ethylene including a first site and a second site, remote from each other, whcrcm the first site fomls an olefinc Fischer-Tropscl1 naphtha to be used at the second site, the second site formmg the ethylene. The process comprises receiving at the second site the olehmic Fischer- I ropsch naphtha, converting the oleEmic naphtha in a naphtha cracker to a product stream comprising ethylene, and Isolating ethylene from the product stream of the naphtha cracker. In this process the olcfinc Fischer-Tropsch naphtha Is made by a process comprising converting a hydrocarbon asset to syngas, subjecting the syngas to Fischer- l ropsch synthesis to form hydrocarbonaceous products, and isolating the oletmc Fscher-Tropsch naphtha from the hydrocarbonaceous products In yet another aspect, the present invention relates to an olefinic naphtha. 'l he oleEmic naphtha composes (a) olefins in an amount of 10 to 80 weight %, (b) non-olefins in an amount of: 20 to 90 weight %, wherein the non-olefins comprise greater than 50 weight % paraffins, (c) sulfur in an amount of less than 10 ppm by weight, (d) nitrogen in an amount of less than 10 ppm by weight, (e) aromatics in an amount less than 10 weight %, (f) a total acid number of less 1.5, and (g) a boiling range of C5 to 400 F.

The present invention also r elates to an olei[inic naphtha comprising (a) olefins in an amount of 25 to 80 weight %, whercn the olefins are comprised of greater than 65 weight % linear prin1ary olefins, (b) non-olefins In an amount of 20 to 75 weight %, wherein the non- olefins comprise greater than 75 weight So paraffins and the paraffins have an An ratio of less than 1, (c) sulfur in an amount of less than 2 ppm by weight, (d) nitrogen in an amount of less than 2 ppm by weight, (e) aromatics in an amount less than 2 weight %, (I) a total acid number of'lcss 1 5, and (g) a boiling range of Cj to 400 ln In anotl1cT aspect, the present invention relates to a process of producing, an olefinic napl1tlla 'I'he process comprises converting at least a portion of a hydrocarbon asset to synthesis gas, and converting at least a portion of the synthesis gas to a hydrocarbon stream in a Fischcr-Tropsch process unit. An olefinc napl1tlla is isolated from the hydrocarbon stream, wherein the oleLn1c naphtha comprises l () to 80 wegh,t RIO olcfins and 2() to '30 weight % non olefins, wleren1 the non-olefins comprise greater than 50 weight % paraffins. The olelinic naphtha is purified by contacting the olefinic naphtha with a metal oxide at elevated temperatures, and a purified oleiinic naphtha having a total acid number of less than 1.5 is isolated.

In yet another aspect, the present invention relates to a blended naphtha. The blended naphtha comprises (a) an olefinic naphtha comprising 10 to 80 weight % olefins and 20 to 90 weight % non-olefins, wherein the nonolefins comprise greater than 50 weight % paral'fns and (b) a naphtha selected from the group consisting of a hydrotreated Fischer-'ropsch derived naphtha, a hydrocracked Fschcr-=l'ropscl1 derived naphtha, a hydrotreated petroleum derived naphtha, a hydrocracked petroleum derived naphtha, and mxttres thereof. The blended naphtha comprises less than 10 ppm sulfur and has an acid number of less than l.5.

In a further aspect, the present invention relates to a process t'or producing a blended naphtha. The process comprises converting at least a portion of a hydrocarbon asset to synthesis gas and converting at least a portion of the synthesis gas to a hydrocarbon stream in a Fscher-'lropsch reactor. An olefinic naphtha Is isolated wherein the olefinic naphtha comprises 10 to 80 weight /0 olcfins and 20 to 90 weight TO non-oleEms, wherein the non olefns comprise greater than 50 weight % paraffins. The olefinic naphtha Is mixed with a naphtha selected from the group consisting of a hydrocracked Fischer-Tropsch derived naphtha, a hydrotreated Fischer-Tropsch derived naphtha, a hydrocracked petroleum derived napltl1a, a hydrotreated petroleum derived naphtha, and mxturcs thereol'to provide a blended naphtha. The blended naphtha comprises less than 10 ppm sulfur and has an acid number of less than 1.5.

In yet a i'urther aspect, the present invention relates to a process for producing a blended naphtlla. The process comprises providing an olefinc naphtha comprising 10 to 80 weight % olefins and 20 to 9() weight TO nonolefins, wherein the non-olefins comprise greater than 50 weight 'I'd paraffins. The olefimc naphtha is mixed with a naphtha selected from the l 0 group consisting of a hydrocracDcd Fischer-Tropsch derived naphtha, a hydrotrcated Fscller- I'ropsch derived naphtha, a hydrocracked petroleum derived naphtha, a hydrotrcatcd pctro]eum derived naphtha, and mixtures thereof to provdc a blended naphtha. The blended naphtha comprises less than 10 ppm sullirr and has an acid number of less than 1.5.

1 5 111tIELF DESCRIPTION OF THE DRAWINGS

Tile Fgurc is an 1lustraton of process for converting natural gas to ethylene with co producton of other salable products.

DETAILED DESCRIPTION OF THE Il,I,USTRATIVE EMBODIMENTS The present nvcntion relates to an olefinc naphtha and a process for producing dower olefins from this olefinic naphtha.

DeJintons The following teens will be used throughout the specification and will have the f'ollowmg meanings unless otherwise indicated.

The teml "naphtha" means a hydrocarbonaceous mixture containing compounds boiling between C5 and 400 F The C5 analysis is performed by gas chromatography, and the 40() F temperature refers to the 95% boiling point as measured by ASTM D- 2887. Preferably, at least 65% of the hydrocarbonaceous mixture boils between Cal and 4()() F, most preferably at least 85%.

The term "paraffin" means a saturated straight or branched chain hydrocarbon (i e., an alkane).

The tend "olefns" means an unsaturated straight or branched chain hydrocarbon having at Icast one double bond (i.e. an alkene).

The ten11 "olefinic napl1tha''mear1s a naphtha containing 10 to 80 wt% oleEn1s and 20 to 90 wt /0 non-olefins, wherein the non-olefins contain predominantly paraffins. Prefcrab]y, olcfinc naphtha contains greater than or equal to 25 to 80 wt% olefins, and more preferably 50 to 80 wt'ho olefir1s. Preferably the non-olefir1s ofthc olelinic naphtha comprise greater than 50 wt% paraffins, more preferably greater than 75 wt RIO paraffins, and even n1ore preferably greater than 90 wt 'S. paraffins (weight % are based on the non-olefin component). Preferably, the olefimc naphll1a also contains less than 1 () ppm sulfur and less than I O ppm nitrogen, and more preferably both sulfur and nitrogen are less than 5 prim, more preferably less than 2 ppm, and even more preferably less than l ppm. Preferably the olei'inc napl1tha contains less than wttgo aromatics, more preferably less than 5 wt% aromatics, and even more preferably less than 2 wt'/o aromatics. Olclins and aromatics are preferably measured by SCF( (Supcrcritcal IT lurid Chromatography).

The tern1 "lower olefins" means olefins having from 2 to 4 carbons. Preferably lower olefins r eI'er to ethylene and propylene, more prep rably ethylene.

l'hc term "hnear primary olefins" n1eans a straight chain 1-alkcne, conrmonly known as alpha olef'ins The term "total acid number" or "acid value" Is a measurement of acidity. It Is determined by the number of milt/grams oI'potassum hydroxide required for the neutralization of'acids present in l gram of the sample being measured (ma KOH/g), as measured by ASTM D 664 or a suitable equivalent. The olefinc naphtha used In the processes of the present invention preferably have a total acid number of' fess than l.5 sing KOE-I/g and more preferably less than 0.5 trig KO/g The tend "oxygenates" means a hydrocarbon containing oxygen, net, an oxygenated hydrocarbon. Oxygenates include alcohols, ethers, carboxylc acids, esters, ketones, and aldeLydes, and the like.

The term An ratio" means isoparaffin/norn1al paraffin weight ratio. It is the ratio of the total nunbcr of iso-paraf'fins (i.e., branched) to the total number of nonnal-paraf'tins (r.e, straight chain) in a given sample.

The term "derived from a Fischcr-Tropsch process" or "Fischcr-Tropsch derived" means that the product, fraction, or feed ongmates from or is produced at some stage by a Fischer- l'ropsch process.

The tcm1 "derived from a petroleum" or "petroleum derived" means that the product, fraction, or feed originates from the vapor overhead streams from dstllmg petroleum crude and the residual fuels that are the nonvaporzable remaining portion. A source of the petrolcum-derved can be from a gas held condensate.

The tend "hydrotrcated Fischer-Tropsch derived naphtha" means a naphtha that is derived lrom hydrotrcating a C5 to 400 F containing FscherTropscl1 product.

Tile tern1 "hydrocracked Fischcr-Tropsch derived naplltlla''nleans a naphtha that is derived from hydrocracking a 400 F+ containing FischcrTropsch product.

I'he term "hydrocrackcd petroleum derived naphtha" means a naphtha that is derived from llydrocracking400 Ft-contamingpetroleunldenved products.

The tem1 "hydrotrcated pctroleun1 derived naphtha'' means a naphtha that Is derived from hy.lrotreating a (5 to 400 E containing petroleum derived product.

Tllc term "elevated temperature" means temperatures greater than 20t'(. In the process of the present invention, elevated tcmperaturcs, with reference to the purification of the olcfnic naphthas, are preferably greater than 450"In It has been surprisingly discovered that an olefinc naphtha produced from a Fischer Tropsch process, rather than a paraffinic naphtha, provides certain advantages. For example, the costs associated with producing the olcfinic naphtha are reduced because a hydroprocessmg step, and thus expensive hydrogen, is not required to manufacture the olefinic naphtha. In addition, when the olelinc naphtha is used to maLc lower olefins, for example ethylene, the yields of ethylene are ulcrcascd because olefins provide higher ethylene Heels than paraffins. Therefore, the amount of feed to a naphtha cracker to produce a desired quantity of ethylene Is less when using an olefin feed m comparison to a paraffin feed.

Furthermore, the opcrabng costs for the naphtha cracker are reduced because the heat of conversion requirements of olefins to ethylene arc less than for the corrcspondng paraffins.

Moreover, existing facilities, such as ships, tanks, pumps, naphtha crackers, etc' can be used when manufacturing an olefinic naphtha and lower olefins from the olefinic naphtha.

Accordingly, the present invention relates to an oleDmc naphtha. The olefnic naphtha of the present invention is made by a Fischer-Tropsch process.

In the Fischer-Tropsch synt]less process, liquid and gaseous hydrocarbons are formed by contacting a synthesis gas (syngas) comprising a rnxture of H2 and CO WIt]l a Fischcr- Tropsch catalyst Rider suitable temperature and pressure reactive conditions. The lischcr-'l'ropsch reaction is typically conducted at temperatures of about from 300 to 700 F (149 to 371 C) prel'erahly about from 400 to 550 F (204 to 228 C); pressures of about from to 6()0 psych, (().7 to 41 bars) preferably 30 to 300 psych, (2 to 21 bars) and catalyst space velocities of about from 1() 0 to 10,000 cc/g/hr, preferably 300 to 3,0()0 cc/g/hr.

Thc products may range from Cal to Cam- with a rnalonty m the C5-Cooi range. Thc reaction can be conducted n1 a variety of reactor types for example, fixed bed reactors containing one or more catalyst beds, slurry reactors, flud.ed bed reactors, or a combination <I f different type reactors. Such reaction processes and reactors are well known and documented in the hter-ature. Slurry Fischer-Tropsch processes, which is a preferred process in the practice of the invention, utilize superior heat (and mass) transfer characteristics for the strongly exotll-nnic synthesis reaction and are able to produce relative' y high molecular weight, paral'Imic hydrocarbons when using a cobalt catalyst. In a slurry process, a syngas comprising a mixture of tl2 and CO is bubbled up as a third phase through a slurry In a reactor which comprises a particulate Fischer-Tropsch type hydrocarbon synthesis catalyst dispersed and suspended m a slurry Squid comprsmg hydrocarbon products of the synthesis reaction which are]iqud at the reaction conditions. Thc mole ratio of the hydrogen to the carbon monoxide may broadly range from about 0.5 to 4, but is more typically within the range of from about 0.7 to 2.75 and preI'erably from about 0.7 to 2.5. particularly preferred Fscher Tropsch process Is taught In EP0609079.

Suitable Fischer-Tropsch catalysts comprise on or more Group VIII catalytic metals such as Fe, Ni, Co, Ru and Re. Additionally, a suitable catalyst may contain a promoter Thus, a preferred Fischer-Tropsch catalyst comprises effective amounts of cobalt and one or more of Rc, Ru, lit, Fe, Nil, Th, Zr, Hf. U. Mg and La on a suitable inorganic support material, preferably one which comprises one or snore refractory metal oxides. In general, the amount of cobalt present in the catalyst Is between about 1 and about 50 weight percent of the total catalyst composition. The catalysts can also contain basic oxide promoters such as ThO2, La2O;, MgO, and TiO2, promoters such as ZrO2, noble metals (Pt. Pd. Ru, Rh, Os, Ir), coinage metals ((flu, Ag, Au), and other transition metals such as Fe, Mn, Ni, and Rc. Support materials including alumina, silica, magnesia and titania or mixtures thereof may be used.

PrcLerred supports for cobalt containing catalysts comprise ttania. Useful catalysts and their preparation arc known and illustrative, but non]imiting examples may be found, for example, in U.S. Pat. Nos. 4,5G8, 663.

Tl1e products from Eischer-Tropsch reactions performed In slurry bed reactors generally include a light reaction product and a waxy reaction product. The hoht reaction product (I e the condensate fraction) includes hydrocarbons boiling below abort 700 F (e.g., tat] gases through middle distillates), largely Al the C5-C20 range' with decreasing amounts UP to about (. Tile waxy reaction product (I e. the wax fraction) includes hydrocarbons boiling above about 600 F (e.g., vacuum gas oil through heavy paraffins), largely in the Cat>+ range, with decreasing amounts down to Call. Both the light reaction product and the waxy product are substantially paraffn1c. The waxy product generally COr11pTSeS greater than 70 /O normal paraffins, and ol'ten greater than 80% normal paraffins. The light reaction product comprises parai'imc products with a significant proportion ol'alcohols and oleln1s. In some cases, the hg]1t reaction product may comprise as much as 50%, and even higher, alcohols. ad olefins.

The olefinic naphtha of the present mventon Nay be isolated from the products of the products ol'thc Fischer-Tropscl1 process by distillation. The olefiT1ic naphtha of the present Invention boils between Cs to 400 F.

In the process of the present Invention, the olefinTc naphtha may be purified. Olefinc naphtha from Eischer-Tropsch facilities l'requently contain Impurities that should be removed, but without saturation of the olefins. Examples of these impurities include acids and heavy metals. The acids present in Fischer-Tropsch naphthas are corrosive and will rapidly attack metal surfaces In ships, tanks, pumps, and the naphtha cracker. Since the acids attack metals, the nctals will become incorporated into the naphtha and lead to ncrcased fouling of furnace tubes m downstream processors, including for example, a naphtha cracker. In addition, metals can be incorporated into the naphtha by direct reaction of the acids with typical Fscher TTOPSCII catalysts - e.g. Iron. Therefore, it may he necessary to remove the acids and dissolved metals present In the olefinic naphtha by a process that can do so without saturating the olefins.

Alcohols and other oxygenates may also be present in the olefimc naphtha from the Fscher-Tropsch facility. While alcohols and other oxygenates can be handled in a naphtha cracker, it can be desirable to remove them as well as the dissolved metals and acids.

In processing conventional petroleum, it is standard that crude oils should have total acid numbers less than ().5 mg KOH/g In order to avoid corrosion problcn. It is lirther standard that distillate fractions have acid numbers less than 1.5 mg KOH/g. See, "Materials Selection for Petroleum Refincres and Gathering Faclitics", Richard A. White, NACE h1tcnlatonal, 1998 Houston'I'exas pages 6-9.

Therefore, the purification processes of the present invention for the olcfinic naphtha are capable of provdhg an olefinc naphtha with a total acid numDcr preferably less than 1.5 mg KOT]/g, more preferably less than 1.0 mg KOH/g, and even more preferably less than 0.5 mg KOI-I/g, without appreciably saturating the olefins contained therein. The olelinic naphtha isolated directly from the Fscher-Tropsch process may have an acceptable total acid number.

Ilowever, if the olefinic naphtha isolated does not have an acceptable total acid number, it will be necessary to purify it as described hercn.

In the conventional technology that produces a highly paraffimc naphtha, nnpurties, including acids, alcohols, and other oxygenates, are removed by a hydroprocessmg technique, for example, hydrotreating, hydrocracking, hydroisomenzation etc. However, these processes also simultaneously convert the desrablc olefins into relatively less desirable paraffins.

According to the present invention, the acids and dissolved metals in Fscher-Tropsch naphthas are removed by contacting the naphtha with a metal oxide catalyst at elevated temperatures. In contacting the naphtha with the metal oxide at elevated temperatures, acids are converted into paraffins and olefins by decarboxylaton. In addition, alcohols are converted into additional olefins by dehydration, and other oxygenates (including ethers, esters, and aldebydes found at relatively smaller amounts) are converted Into hydrocarbons. In this process for purification of naphtha, expensive hydrogen is not needed; however, it can be used If dcsred (to improve catalyst/naphtha contacting or for heat control). The oxygen m the naphtha is converted into water and carbon dioxides which can easily be separated from the product olefinic naphtha.

If dissolved metals are present in the naphtha, they will be simultaneously removed and deposited on the metal oxide catalyst. Typically, the metal oxide catalysts used in the purification process according to the present invention will show low deactivation rates; however, eventually the catalysts will need to be regenerated or replaced. Regeneration of the catalysts can be accomplished by stripping with a high temperature gas (hydrogen or other), or by bumping the catalyst while it Is In contact with an oxygen containing gas at elevated temperatures. Regeneration by burning Is prcl'erred.

Preferably the purification according to the present invention Is performed by passing the olefinic naphtha through a purl location unit contammg a metal oxide under conditions of 45() to 800 I<, less than 1000 psi", and 0 25 to 10 LI-ISV without added gaseous components. T]y way of'examplc, the purification process may be pcrfonncd by passmg

the olefimc naphtha downflow through a purt'ication unit containing a metal oxide at elevated temperatures.

Preferably, the metal oxide is selected from the group consstn1g of alumina, silica, shca-alumna, zcoltes, clays, and rmxtures thereof. Since terminal olefins are believed to give the highest ycld of ethylene, it Is prci'crable to select an oxide that is effective for dehydration of the oxygenates, yet does not promote isomerization of the olelms from their terminal position to Internal or branched olefins. On this basis, a preferred metal oxide Is alumina. Additional components can be added to the metal oxide to promote the dehydration or retard olefin isomerz.ation. Examples of such additional components are basic elements such as Group T or It elements of the periodic table. These basic components can also retard catalyst fouling. Usually these components are Incorporated into the oxide fond in the finished catalyst.

The severity of'thc puriOcaton process can be varied as necessary to achieve the desired total acid number. Typically the severity of the process is varied by adjusting the temperature, and LHSV. Accordingly, a more severe puriEcaton may be accomplished by running the purification process at a higher temperature, and under these more severe purification conditions more oxygenates will be removed, thus providing an oleOnic naphtha with a lower total acid number.

l'he pun [;caton processes of the present invenhon provide an olciinic naphtha with a total acid number preferably less than 1.5 sing KOH/g, more preferably less than 1.0 mg KOH/g, and even more preferably less than 0.5 mg KOH/g, without saturating the olefins contained therein. The purification processes of the present invention preferably remove more than 80 weight percent of the oxygenates in the olefinic naphtha.

The oceanic naphtha according to the present invention is a naphtha containing 10 to wt% olefins and 20 to 90 wt % non-olef ns, wherein the non-olefins contain predominantly paraffins. Preferably, olefinc naphtha contains greater than or equal to 25 to 80 wt% olefins, and more preferably 50 to 80 wt % olcfns. The oleOms of the olefinc naphtha are predominantly linear primary olehms. Preferably, the olefins compose greater than 50 wt % linear primary olefins, more preferably greater than 65 wt % hnear primary olefins, and even more preferably greater than 8() wt % hnear primary olefins.

The non-olefimc component of tile olef;mc naphtha is predominantly parat'finc.

Preferably the non-olefrls conprisc greater than 50 wt % paraffins, more preferably greater than 75 wt % paraffins, and even more prcLerably greater than 90 wt % paraffins (as measured on the basis of the nonolelinic component). The paraffins of'the non-:'lefinc component of the naphtha are predominantly n-parafTh1s. Preferably the paraffins have an i/n ratio of less than 1.0 and more preferably less than ().5 In addition, preferably, the olefirlic naphtha also contains less than 10 ppm sulfur and less than 10 pprn nitrogen, and more preferably both sulfur and nitrogen are less than 5 ppm, nore preferably less than 2 ppm, and even more pref'eraly less and I ppm. Furthermore, the olefimc naphtha preferably contains less than 10 wt% aromatics, snore preferably less than 5 wt% aromatics, and even more preferably less than 2 wt% aromatics. Olefins and aromatics are preferably measured by SCFC (Supercritical Fluid Chromatography).

The olefinic naphtha according to the present invention may be blended to provide a blended naphtha. This blended naphtha may be used for any purpose for which a naphtha is used These purposes include processes for producing cthylcne, including both traditional processes and the process of the present invention. A blended naphtha comprises the olcfinic naphtha as described above and a naphtha selected from the group consisting of a hydrotreatcd Fischer-Tropsch derived naphtha, a hydrocracked Fischer-Tropsch naphtha, a hydrotreated petroleum derived naplltlla, a hydrocracked petroleum derived naphtha, and mixtures thereof.

The blended olefinic naphtha according to the present invention Is made by a process comprising mixing an appropriate amount of an oleEnc naphtha, as described herein, with another naphtha selected from the group, as defined above, to provide a blended naphtha. The olefinc naphtha may be made by processes as described herein.

The blended naphtha according to the present invention comprises less than 10 ppm sulfur and has an acid number of less than 1.5 mg KOH/g Preferably, the blended naphtha has an acid number of less than 0.5 mg KOH/g. Also, preferably the blended naphtha also contains less than 10 ppm nitrogen, and more preferably both sulfur and nitrogen are less than ppm, more preferably less than 2 ppm, and even more preferably less and I ppm. In addition, preferably the blended napEtlla comprises less than 10 weight /O aromatics, more prelcrably less than S weight /O aromatics, and even more prcf'erably less than 2 weight X, aromatics.

The bonded naphtha according to the present invention may conpusc varying amounts oi'olefinic naphtha versus the other naphtha as deiinecl above. Prel'crably, the, olefnc naphtha comprises 10 to 90 weight % olefinc naphtha and 9() to 10 weight TO other naphtha as defined above. More preferably a blended naphtha comprises 30 to 7() weight RIO olefnc naphtha and 7() to 30 weight g, other naphtha.

The olcfnic nal.htlla ol'the present invention provcles a superior fee:l for a naphtha cracker for the production of lower olefins. 'lithe process for producing lower olefins according to the present n1venton comprises converting at least a portion of the olefinic naphtha, as described above, In a napiltlla cracker to a product stream comprising lower olefins and lower olefins arc;ecovercd from this product stream.

Thermal cracking of hydrocarbons is the principal route for the industrial production of ethylene. Typical conditions for conducthg thermal cracking to produce ethylene are described m K.M. Sundaram, et al. , Et/?ylel?e, Kirk-Otlner Encyclopedia of Chemical Technology, April 1 G. 2001, herein ncoporatcd by reference in its entirety. The thermal cracking reaction proceeds in pyrolysis coils of a radiant section of a f'unace. Since coke Is also formed during pyrolysis, steam is added as a diluent to the feed. 'lhc steam minimizes the side reaction fowling coke, and Improves selectivity to produce the desired olefins by lowering hydrocarbon partial pressure. The temperature of the hydrocarbon and steam mixture entering the radiant chamber (known as the crossover temperature) Is 500 to 700(.

Dependmg on the residence time and required feed severity, the coil outlet temperature is typically maintained between 775 and 950 C. The conbnaton of low rcsdence tune and low partial pressure produces Ugly selectivity to olef'ins at a constant aced conversion. In the 1 960s, the residence time was 0.5 to 0.8 seconds, whereas in the late 1980s, residence time was typically 0.1 to 0.15 seconds.

Typical pyrolysis heater characteristics are given in the below table.

Table. Pyrolysis Heater Characteritics Single heater characteristic flange number of coils 2-176 coil lengtl1, m 9-80 Inside coil diameter, mm 30-200 process gas outlet temperature, C 750-950 clean coil metal temperature, 'C 9()0-1,080 max metal temperature, C 1,()40- 1, 150 average heat absorption, kW/m2 ext. are a 50-110 bulk resdcnce tunic, s 0.1 -0 6 coil outlet pressure, kPaa 150-275 clean coil pressure drop, kPaa 1()-200 " To conVcit kl'a to bar, divide by 100 Cracking reactions are endothermic, 1.6-2.8 MJ/kg (700-1200 BTU/lb) of hydrocarbon converted, with heat,upphed by firing fuel gas and/or fuel oil in sde-wall of floor burners.

Sde-wall burners usually grvc unfoml heat distribution, but the capacity of each burner is hmited (0.1-1 MW) and hence 40 to 200 burners are required in a single fumacc. With modem floor burners, also called hearth burners, unicorns heat flux distribution can be obtained for coils as high as 10 m, and these are extensively used in newer designs. The capacity of these burners vary considerably (I -10 MOO), and hence only a few burners arc required. The selection of burners depends on the type of fuel (gas and/or liquid), source of combustion air (ambient, preheated, or gas turbine exhaust), and required NOX levels. The reaction mixture exiting the furnace is quickly cooled in quench coolers.

Using the olefinic naphtha, as described above, as the feed to a naphtha cracker mcreascs the yields of ethylene m comparison to paraff nic naphtha. The improvement in yields of ethylene during naphtha cracking can be understood by examining the chemistry of naphtha cracking. For a typical C6 paraffin, the cracking reaction (without deLydrogenation) is as follows: C6H4 2C2H4 + C2H6 Accordingly, one mole of hexane gives two moles of ethylene and one mole of ethane.

The reaction for the corresponding C6 olehm the reaction Is as follows: C6H2 3C24 Since the olefin is hydrogen deficient m comparison to the paraffin, less low-valued ethane is produced and the yield oi'desred ethylene potentially Increases by 50 /0. However, under commercial conditions a portion ol'the starting hexane would be dellydrogenated to form hexene and hydrogen, thus Increase the actual yield of ethylene over what would be expected without debydrogenation. Nevertheless, when olcfinic feeds are used, ethylene yields are increased over what is observed with the corresponding paraffins. Accordingly, the cracking reaction of the present invcnton Is more efficient since it uses an olefimc naphtha feed, as described above Furthemlorc, the cracking r Faction of the present invention using an olcTinc naphtha l'eed Is more economical. While both conversions of'paraL'I;ns (ye., hexane) and olefins (I e., hcxanc) to ethylene are endolhemnc and thtis rcqure high temperatures, the conversion of olefins Is less endothermic than the conversion of paraffins because the cndotllcrmic deLydrogenaton reaction does not occur to the same extent. Accordingly, thus energy consumption during convcrsio n of olcfinc naphtha to ethylene Is lower than what won l be expected for the corresponding paraffin. This lower energy consumption reduces the operating cost of the steam cracker.

It should be noted that current feedstocks used in naphtha crackers do not contain significant amounts of olefins because they are derived from petroleum, which is typically devoid of these compounds.

Tile processing of an olefinic feedstock in a naphtha cracker may result in an increase In the furnace tube coking rate. However, if this happens, any one or combinations of the following actions Nay be taken to control this problem. 'I'hcsc actions include increasing the frequency of decoding operations, ncrcasing the H2O/hydrocarbon feedstock ratio, adding sulfur or a sulfur-containing stream to the feedstock, and coating the reactor with a coke passvaton agent such as tm, chromium, aluminum, germanium, and combinations thereof.

In the process ol'the present invention for producing lower olefins, at least a portion of a hydrocarbon asset Is converted to synthesis gas. The hydrocarbon asset may be selected from the group consisting of coal, natural gas, petroleum, and combinations thereof. At least a portion of the synthesis gas is converted to an olefinic naphtha by a FischerTropsch process, as described above. The olefinic naphtha is isolated from the Fischer-Tropsch product stream and may be optionally purified by contacting with a metal oxide at elevated temperatures, also as described above. At least a portion of the olefinc naphtha Is converted In a naphtha cracker to a product stream comprising lower olefiTls and at least a portion of the lower olefins are recovered from the product stream. Preferably, these lower olefins comprise ethylene.

A preferred embodiment of the present mventon is illustrated in Figure I. In a location remote from the ethylene manufacttnng plant, methane (10) is mixed with oxygen and steam (neither Sl10WT1) and reacted n1 a synthesis gas generator (20) to form a synthesis gas stream (3()) 'l'he synthesis gas is reacted m a slinky phase FischcT--rl'ropsch unit (40) to produce a liquid phase product (50) and a vapor phase product (6()). '['he vapor phase product is separated to form a distillate range material (9()) which contains (0 and greater hydrocarbonaceous compounds. Also produced IT1 this separation is an olefinic naphtha (8()), whack contains (is to 400 F hydrocarbonaceous compounds. 'the olcfiTlc napttlla Is passed downflow throug}1 a purification unit (100) at 680',1i, 50psig, and 5 LHSV without added gaseous components. 'lithe punficaton unit contains altmma. The purficato'1 unit removes more thaw 801/o Of the oxygenated compounds increases the olefin content, and reduces the acidity of the olefinc n,htlla. A purified olefinic napttlla is produced ( 120) and shipped (140) to an ethylene manufacturing site where it is cracked in a naphtha cracker (160) to produce an ethylene containing stream (170). Sa]ablc, ethylene Is recovered from the ethylene containing stream by steps not shown.

Meanwhile, the liquid phase product from the Fscher-rl'ropsch facility (50), which contains 400 -- material, Is blended with the distillate range material (90) and the blend Is processed iT1 a hydrogenation facility (1 10) that converts the product into salable products: diesel fuel,et Mel, and/or lubricating oil base stock (130). The hydrogenation facility consists of hydrocrackmg, hydrotreating, and/or hydroisomerization steps. Tllese salable products are shipped (150) to markets (180). Altematvely, paraffinc naphtha (not shown) produced in the hydrogeTlatioTl facility (1 10) along with other salable products can be blended with the ptn-fied olefinic naphtha (120) and shipped.

The optional purification treatment of the olcfinic naphtha can be performed either before shipping (as shown above) or after shipping and prior to conversion in the steam cracker, or it can be performed at both locations.

EXAMPLES

The invention will be further explanted by the following lltstratve examples that are intended to be non-hmting.

Example 1: Fischer-Tropsch Olefinic Naphtl1as Two olefinic napl1tlJas prepared by the Fischer-'lropsch process were obtained. The first (T; eedstock A) was prepared by use of a iron catalyst. 'lithe second (Feedstock B) was prepared by USC of an cobalt catalyst. The FischerTropsc}1 process used to prepare both feeds was operated in the slurry phase Properties of the two feeds are shown below in Table 4 to follow.

Feedstock A contains significant amounts of dissolved iron and is also acidic. it has a significantly poorer corrosion rating.

For purposes of this nvcntion, Feedstock B is preferable IL contains f'ewcr oxygenates, has a lower acid content, and is less corrosive. Thus it is preferable to prepare olefinc naphtha for use m ethylene production from cobalt catalysts rather than iron catalysts Naphtha Prom cobalt catalysts may have low enough levels of impurities that the naphtha may be able to be used without further treatment or purf.-ation, as described above.

A modified version of ASTM D6550 (Standard Test Method for the Determination ol' the Olefin (content of Gasolines by Supercritical Fluid Chromatography - SFC) was used to detenninc the group types in the feedstocks and products. The modl'ied method Is to quantify the total amount of saturates, aromatics, oxygenates and olefins by making a 3point calibration standard. Calibration standard solutions were prepared using the following compounds: undecane, toluene, n-octanol and dodecene. External standard method was used for quantification and the detection Unfit for aromatics and oxygenates is 0.1 k, wt and for olefins is 1.0% wt Please refer to ASTM D6550 for nstrun1ent conditions.

small aliquot of the fuel sample was injected onto a set of two chromatographic columns connected m series and transported using supcrcritical carbon dioxide as the mobile phase. The first column was packed with high surface area silica particles. The second column contained Hall surface area silica particles loaded with silver ions.

Two switching valves were used to direct the different classes of components through the chromatographic system to the detector. In a forward-flow mode, saturates (normal and branched alkanes and cyclic alkalies) pass through both columns to the detector, while the olefins are trapped on the silver-loaded column and the aromatics and oxygenates are retancd on the silica column. Aromatic compounds and oxygenates were subsequently elated from the silica column to the detector in a back flush mode. Fn1ally the oleDns wore back flushed trom the slver-loaded column to the detector.

A flame Ionization detector (FID) was used for quantification. Calibration was based on the area of the cl1ronlatographic signal of saturates aromatics oxygenates and olcfins relative to standard reference matcrals which contam a known mass % of total saturates aromatics oxygenates and olcfins as corrected for density. The total of all analyses was within 3% ol 100% and normalized to 100% for convenience The weight percent olefins can also be calculated Dons the bromine ntunber and the average molecular weight by use of the following fonnula: Wt% Gleans = (Broninc No.)(Average Molecular Weght)/159.8.

It Is preferable to measure the average molecular weight directly by appropn ate methods but it can also be estimated by correlations using tlc API gravity and md-bohng pon1t as described in "Prediction of Molecular Welt of Petroleum lractions" A.G.(Joosscus IEC Res. 1996 35 p. 985-988.

Preferably the olcfns and ogler components are mcast. cd by the modified SFC mct]1od as described above.

A GCMS analysis of the feedstocks determined that the saturates were almost exclusively e-paraffins and tle oxygenates were predominantly primary alcohols and the olefins were predominantly primary linear cleans (alpha olefins).

Example 2 - Dehydration catalysts (ontmcrcial Shca Alumina and Alumina extrudates were evaluated for dehydration of the Olcfinc Naphthas. Properties of the extrudates are shown below in Table 1.

Table l

Extrudate Si Pica Alumina Alumina Method of manufacture 890io silica alumina Alumina extudate powder bound with 11% alumina Particle Density gm/cm3 _ _ 0.959 1.0445 Skeletal Densi y gn Icm3_ __ 2.837 __ BET Surface a ea. m2/g _ _ _ 416 _ 217 _ _ _Geometric Average pore size Angstroms_ 54 101 _Macropore volume cc/g (1000+ Angstroms)_ 0.1420 0.0032 Totalpore volume cc/g _ 0.636 0.669_ Example 3 - Dehydration over Silica Alumma The dehydration experiments were performed m one inch downflow reactors without added gas or liquid recycle. The catalyst volume was l 20 cc.

The E-based condensate (Feed A) was treated with the commercial silica alumina.

This catalyst was tested at 50 psg and temperature of 480 F, 580 F, and 680"F with space velocity at one LHSV and three Ll-:SV. At one Ll-lSV, the total olefin content was 69-70% at all three temperatures, which indicated full conversion of tle oxygenates. At 680 F some cracking was observed by the light product yields: total C4- was l.2% and C5-29() F was 25% (vs. 20% In the feedstock). At three l,llSV and 480 F and 580 F the total olefins were lower at 53-55% High dchydraton activity was obtained at 680 F and three LUSV with total olefin content of 69%. GCMS data indicated that significant amount of l-olefin was converted to ntcnal or branched olefins. The total olefins at 480 F was 69% initially but was 55 /O near the end ofthe test (960 hours on stream). Significant amount ol carbon was observed on the catalyst after unloading the catalyst. The catalyst apparently fouled.

Table 2

Dehydration _. Bromine G(-MS Data l'P72-457, method S-A1 catalyst _.

I'emp, F LHSV llromine# %OleGn Alpha-olefls/'l'otal Clefts Sample A 50 6 51 6 9()XO Product 1) 680 3 71 7 70.3 5oX' 680 1 72 2 70 5 (AX, The detailed analysts of the product (D) from the test at 3 LHSC and 680"F is shown below in Table 4. 84% of the oxygen was removed, the corrosion raking was improved, and iron was reduced to below the love] of detection. The acidity of the naphtha was reduced by 25/o. 1 he oxygenates were converted to olefins as shown by the increase in olcfin content and the decrease m oxygenate content.

Example 4 - Dehydration over Alumina The Co-bascd cold condensate (Feedstock B) was also treated as in Example 2, but with the alumma catalyst. Temperatures from 48() F to 730 F and LHSV values from one to five were explored At high temperature and one LElSV, GCMS data indicated that the double bond somerization was significant (reduced alpha-olefin content). At five LHSV and 580 E7, dehydration conversion was significantly lower, and the majority of the olefins were primary linear olefins. This test ran 2000 hours with no indication of fouling.

Table 3

Dehydration SFC method Bromine Chop GC-MS PP72-461461, Data alunia catalyst Sample 11) Hemp, F I,HSV Oxygenates, Bronine# X,Oletin Alpha(4- ('as I'ota "X,wt oletins/Tot:l Yiclds Acid olefins Wt',/i, No. Feed B _ 8 G 20 4 24 2 94% 0 X6 480 1 7 4 21 3 25 2 92, 0 32 SS0 1 0 9 27 5 31 85 /) < 0 5

_ ___

580 1 08 282 33 1 91tJ/o 034 ()6 i80 1 () 9 27 1 31 1 93/, 0 36 __ _ _ _ 580 2 1.3 27 1 31 3 8G /;, < () 5 580 3 2 l 26 5 30 6 8G , < () 5 1 0 48 (30 1 O.(i 27 9 32 2 78% O 46 _ () 32 630 2 0 8 28 1 32 4 79 G '8 630 3 0 8 29 4 33.9 86 /;, O 24 0 63 G30 4 1 0 28 7 33 1 87% O 20 630 5 1.1 27 1 31 1 83% O 18 0 67 680 1 <0.1 31 1 35.6 4> 0 51 0 06 G80 2 0 3 26.7 30 8 30' 0 40 0 18 680 3 0 5 26 5 30 6 717o O 33 680 3 0 6 26.9 31.1 78/o < 0 5 G80 4 0 6 27.6 32 0 76 ) < 0 5 680 4 0 6 29 1 33 3 73% 0 20 680 5 0 7 28 1 32 3 78% 0 18 0 39 G80 5 0 7 27.8 31 9 79% < 0.5 = 730 3 0 1 31 36 1 7% 0.33 0 IZ These results show that it is possible to eliminate all the oxygenates from the sample and convert them to olefins. At high oxygenate removal levels, a significant portion of the alpha olelins are somenzed to internal olefins. Although internal olefins have less value than the alpha olefins as a feedstock for ethylene production, isomerization to internal olefins does not reduce the value below standard paraffnic naphtha or destroy any value for the feedstock.

Product (C) was prepared from operation at five LIISV and 680 F. Dctailed properties are shown below in Table 1. 87% of thc oxygen is removed, the acidity was redced by 55%, ard the trace of iron n tile sample was removed. The acdity of tile final naterial was below ().5 mg KOI-l/g, the typcal naxml1 for petroleum cruclos. The oxygenates were converted to oleiis as showr1 by thc increase n olefin content which approxnately matched the decrease in oxygenate content.

Table 4

lixpenmel1t No _ - _ _ _ _ 3 Fcedil'lo(luct IO Pc CC.olld Plociuct (lo Con(l Product A 1:) E] C Process condtlolls.... . ___. .__ C:atalyst None SIAl None Allmn1a L.IISV, h-1 3 5 fcmperatule, I; 680 680 PlesSUre, pSlg __ _ _ 5() .... 50 Rn hoil-s 582-678 1026-1122 API 56 5.. . S8 1 _ 56 6 1 57 9 13'omlne No. _ 50 6 _ _ 71 7. _21 27 6 Average molecular wclgllt 16 157 1 X3 184

-

Wt t1/o Olefin 51 6 70 3 24 32 (calc from Br2 No) KE Water, ppl11 wt ___494 58_ S30 __ _ 57 Oxygen by NAA, wt% ___I 6 I 0 26_ 0 95 _ 0.12 ST C Analysis, Wtto Sattll ates 35 1 67 4.... - _. ... _ _ _ _ _ Aron1atcs _ 1 2 1 5 __ () 3 _ 0 4 _ OlefLns = 55 7 _ 62 2 23 7 30.9= _ Oxygenates _ __ 9 6 1.2 8 6 _ 0.7 Accl Icst _._... . ._ _. ..... _ _ I otal Acld, rug KOH/g _ 3 17 _ 2 33 0 86 0 39 131.JT_.P,111g KO11/g 3 10 2 30 0.84. 0.35 Ctl Stnp Corr(_ on.... _. _. _ _Ratmg 2c ___ 2a _ lb _ lb Sulfur,ppll wt _ _ <i _ n/a.. ! _< I_ _Nitrogcn, ppm _ _ 0 56 n/a 1 76 _ 1 29 ASTM D2887 Snnulated Dlstllaton by Wt0/o, 1; 0 5 86 102 76 91 237 214 243 247 301 303 339 338 373 356 415 414 417 417 495 486 484 485 569 572 517 518 596 599 99.5. _. _ 639 622 662 __ 666 _ Metals by ICP, pprn __.. . _ Fe. . --- 44 960 0.980 _ 2 020 <0 610 7n _ _ _ 2 610 <0.380 <0 360 <0.350 Metal elements below ICP limit of detection in all san:lples: Al,B,Ba,Ca,Cr,Cu,K,Mg,Mo,Na,Ni,P,Pb,,,Si,Sn, Ti,V.

Example 5 --- Adsorption of Oxygenates Trace levels ol'oxygcnates not removed by the high temperature treatment can be removed by adsorption using sodun1 X neolith (commercial 13X sieve from EM Science, Type 13X, 812 Mesh Beads, Part Number MX1583T-I).

I'he adsorption test was castled out in a up-flow f'ixecl bed unit. The feed for the adsorption studies was produced by processing the (to condensate (Feed B) over alumn1a at 5 L,l-ISV, 680"E and 50 psi". The feed for the adsorption studies had acid number of 0.47 and oxygenate content by SFC oi'O.6 /O Process conditions for the adsorption were. ambient pressure' room temperature, and () 5 LHSV. The oxygenate content of the treated products was monitored by the SFC method.

'I'he adsorption expernnent was eontn1ued until brcakthrougl1 - defined as the appearance of an oxygenate content of 0.1% or hgl1er. The breakthrough oeer.rred at when the sieve had adsorbed an equivalent amount of 14 wt /. based on the feed and product oxygenates. The product after treatment showed 0.05 wt% oxygen by neutron activation, <0.1 ppm nitrogen, and total acid number of 0.()9.

The adsorbent could be regenerated by known methods: oxidatve combustion, ealenatons In inert atmosphere, water washing, and the like, and In combulatons.

These results demonstrate that adsorption processes can also be used for oxygenate removal. They can be used as such, or combined with dehydration.

Various modrfieations and alterations of this Invention will become apparent to those skilled in the art without departing from the scope and spirit of this invention. Other objects and advantages will become apparent to those skilled in the art from a r eview of the preceding descnption. - 24

Claims (79)

1. Claims 1. A blended naphtha comprising: a. an olefinic naphtha comprising

   olefins in an amount of 10 to 80 weight % and non-olefins in an amount of 20 to 90 weight %, wherein the non- olefins comprise greater than 50 weight % paraffins; and b. a naphtha selected from the group consisting of a hydrotreated Fischer Tropsch derived naphtha, a hydrocracked Fischer-Tropsch derived naphtha, a hydrotreated petroleum derived naphtha, a hydrocracked petroleum derived naphtha, and mixtures thereof, wherein the blended naphtha comprises less than 10 ppm sulfur and has an acid number of less than 1.5.
2. 2. A blended naphtha according to claim 1, wherein the blended naphtha has an acid number of less than 0.5.
3. 3. A blended naphtha according to claim 1, wherein the blended naphtha comprises less than 5 ppm sulfur.
4. 4. A blended naphtha according to claim 1, wherein the blended naphtha comprises less than 2 ppm sulfur
5. 5. A blended naphtha according to claim 1, wherein the blended naphtha comprises nitrogen in an amount of less than 2 ppm and aromatics in an amount of less than 2 weight %.
6. 6. A blended naphtha according to claim 1, wherein the oleQnic naphtha comprises at least 25 weight % olefins.
7. 7. A blended naphtha according to claim I, wherein the olefins of the olefinic naphtha comprise greater than 65 weight % linear primary olefins.
8. 8. A blended naphtha according to claim 1, comprising 10 to 90 weight % olefinic naphtha and 90 to 10 weight % naphtha of (b).
9. 9. A process for producing a blended naphtha comprising: a. converting at least a portion of a hydrocarbon asset to synthesis gas; b. converting at least a portion of the synthesis gas to a hydrocarbon stream in a Fischer Tropsch process reactor; c. isolating an olefinic naphtha comprising 10 to 80 weight TO olefins and to 90 weight % non-olefins, wherein the nonolefins comprise greater than 50 weight % paraffins; and - 25 d. mixing the olefinic naphtha with a naphtha selected from the group consisting of a hydrocracked Fischer Tropsch derived naphtha, a hydrotreated Fischer Tropsch derived naphtha, a hydrocracked petroleum derived naphtha, a hydrotreated petroleum derived naphtha, and mixtures thereof to provide a blended naphtha, wherein the blended naphtha comprises less than 10 ppm sulfur and has an acid number of less than 1.5.
10. 10. A process according to claim 9, further comprising the step of purl fying the olcfinic naphtha to reduce dissolved solids and acids therein.
11. 1 1. A process according to claim 10, wherein the purl fying step is performed by contacting the olefinic naphtha with a metal oxide at elevated temperatures.
12. 12. A process according to claim 1 1, wherein the metal oxide is selected from the group consisting of alumina, silica, silica-alumina, zeolites, clays, and mixtures thereof.
13. 13. A process according to claim 10, wherein the purified naphtha has a total acid number of less than 0.5.
14. 14. A process according to claim 10, wherein the purifying step is performed by passmg the olefinic naphtha through a pur location unit containing a metal oxide at 450 to 800"F, less than 1000 psi", and 0.25 to 10 LHSV without added gaseous components.
15. 15. A process according to claim 9, wherein the blended naphtha comprises 10 to weight % olefinic naphtha.
16. 16. A process according to claim 9, wherein the blended naphtha comprises less than 2 ppm sulfur.
17. 17. A process for producing a blended naphtha comprising a. providing an olefinic naphtha comprising 10 to 80 weight % olefins and 20 to 90 weight % non-olefins, wherein the non-olcfins comprise greater than 50 weight % paraffins; and b. mixing the olefinic naphtha with a naphtha selected from the group consisting of a hydrocracked Fischer Tropsch derived naphtha, a hydrotreated Fischer Tropsch derived naphtha, a hydrocracked petroleum derived naphtha, a hydrotreated petroleum derived naphtha, and mixtures thereof to provide a blended naphtha, - 26 wherein the blended naphtha comprises less than 10 ppm sulfur and has an acid number of less than 1.5.
18. 18. The process according to claim 17, wherein the olefinic naphtha comprises 25 to 80 weight % olefins and 20 to 75 weight % non-olefins, wherein the non olefins comprise greater than 75 weight % paraffins and the olefins comprise greater than 50 weight % linear primary olefins.
19. 19. The process according to claim 17, wherein the olefinic naphtha comprises 50 to 80 weight % olefins and 20 to 50 weight % non-olefins, wherein the non olcfins comprise greater than 75 weight % paraffins and the olefins comprise greater than 65 weight % linear primary olefins.
20. 20. A process according to claim 17, wherein the blended naphtha has a total acid number of less than 0.5.
21. 21. A process according to claim 17, wherein the blended naphtha comprises 10 to weight % olefinic naphtha.
22. 22. A process according to claim 17, wherein the blended naphtha comprises less than 2 ppm sulfur.
23. 23. An olefinic naphtha comprising: a. olefins in an amount of 10 to 80 weight /, b. non-olefins in an amount of 20 to 90 weight %, wherein the non olefins comprise greater than 50 weight % paraffins; c. sulfur in an amount of less than 10 ppm by weight; d. nitrogen in an amount of less than 10 ppm by weight; e. aromatics in an amount less than 10 weight %; f. a total acid number of less 1.5; and g. a boiling range of Cs to 400 F.
24. 24. An olefinic naphtha according to claim 23, comprising at least 25 weight /O olefins.
25. 25. An olefinic naphtha according to claim 23, comprising at least 50 weight % olefins.
26. 26. An olefinic naphtha according to claim 23, wherein the non-olefins comprise greater than 75 weight % paraffins.
27. 27. An oleOnic naphtha according to claim 23, wherein the non-olefins comprise greater than 90 weight % paraffins. - 27
28. 28. An olefinic naphtha according to claim 23, wherein the olefins are comprised of greater than 50 weight % linear primary olefins.
29. 29. An olefinic naphtha according to claim 23, wherein the olefins are comprised of greater than 65 weight % linear primary olefins.
30. 30. An olefinic naphtha according to claim 23, wherein the olefins are comprised of greater than 80 weight % linear primary olefins.
31. 31. An olefinic naphtha according to claim 23, wherein the paraffins have an i/n ratio of less than 1.
32. 32. An olcfinic naphtha according to claim 23, wherein the paraffins have an i/n ratio of less than 0.5.
33. 33. An olefinic naphtha according to claim 23, comprising sulfur in an amount of less than 2 ppm by weight and nitrogen in an amount of less than 2 ppm by weight.
34. 34. An olefinic naphtha according to claim 33, comprising aromatics in an amount of less than 2 weight %.
35. 35. An olefinic naphtha according to claim 23, comprising a total acid number of less than 0.5.
36. 3G. A recess for producing lower olefins comprising: a. converting at least a portion of a hydrocarbon asset to synthesis gas; b. converting at least a portion of the synthesis gas to an olefinic naphtha by a FischerTropsch process; c. converting at least a portion of the olefinic naphtha in a naphtha cracker to a product stream comprising lower olefins; and, d. recovering at least a portion of the lower oleUns from the product stream of the naphtha cracker.
37. 37. A process according to claim 36, wherein the olefinic naphtha has a total acid number of less than 1.5.
38. 38. A process according to claim 36, further comprising the step of purifying the olefinic naphtha to reduce dissolved solids and acids therein to provide a purified naphtha.
39. 39. A process according to claim 38, wherein the purified olefinic naphtha has a total acid number of less than 0.5.
40. 40. A process according to claim 38, wherein the purifying step is performed by contacting the olefinic naphtha with a metal oxide at elevated temperatures. - 28
41. 41. A process according to claim 40, wherein the metal oxide is selected from the group consisting of alumina, silica, silica-alumina, zeolites, clays, and mixtures thereof.
42. 42. A process according to claim 36, further comprising the step of separating water and carbon dioxide formed in the purifying step from the purified naphtha.
43. 43. A process according to claim 36, wherein the olefinic naphtha comprises lO to weight percent olefins and 20 to 90 weight percent nonolefins, wherein the non-olefins comprise greater than 50 weight percent paraffins.
44. 44. A process according to claim 36, wherein the olefinic naphtha comprises 50 to weight percent olefins and 20 to 50 weight percent nonolefins, wherein the non-olefins comprise greater than 50 weight percent paraffins.
45. 45. A process according to claim 36, wherein the olefinic naphtha comprises less than 5 weight percent aromatics, less than 5 ppm sulfur, and less than 5 ppm nitrogen.
46. 46. A process according to claim 43, wherein the olefins of the olefinic naphtha comprise greater than 50 weight % linear primary olefins.
47. 47. A process according to claim 43 wherein the olefins of the olefinic naphtha comprise greater than 80 weight % linear primary olefins.
48. 48. A process according to claim 36, further comprising the step of blending the olefinic naphtha with a naphtha selected from the group consisting of a hydrotreated Fischer-Tropsch derived naphtha, a hydrocracked Fischer Tropsch derived naphtha, a hydrotreated petroleum derived naphtha, a hydrocrackcd petroleum derived naphtha, and combinations thereof to provide a blended naphtha and converting a least a portion of the blended naphtha in the naphtha cracker.
49. 49. A process for producing ethylene comprising: a. converting at least a portion of a hydrocarbon asset to synthesis gas; b. converting at least a portion of the synthesis gas to a hydrocarbon stream in a Fischcr-Tropsch process unit; c. isolating an olefinic naphtha from the hydrocarbon stream, wherein the olefinic naphtha comprises 25 to 80 weight % olefins and 20 to 75 weight % non-olefins, wherein the non-olcfins comprise greater than weight % paraffins; - 29 d. purifying the olefinie naphtha in the presence of a metal oxide to provide a purified olefinie naphtha having a total acid number of less than 1.5; e. converting at least a portion of the purified olefinie naphtha in a naphtha cracker to a product stream comprising ethylene; and f. recovering at least a portion of the ethylene from the product stream of the naphtha cracker.
50. 50. A process according to claim 49, wherein the olefins of the olefinie naphtha comprise greater than 50 weight /0 linear primary olefins, the non-olefins of the olefinic naphtha comprise greater than 90 weight % paraffins, and the paraffins have an i/n ratio of less than 1.
51. 51. A process according to claim 49, wherein the purification step reduces the content of solids, acids, and alcohols in the olefinie naphtha.
52. 52. A process according to claim 49, wherein the purified olefinie naphtha has a total acid number of less than 0.5.
53. 53. A process according to claim 49, wherein the purification step is performed by passing the olefinie naphtha through a purification unit containing a metal oxide under conditions of 450 to 800 F, less than 1000 psi", and 0.25 to 16, Ll-ISV without added gaseous components.
54. 54. A process according to claim 49, wherein the metal oxide is selected from the group consisting of alumina, silica, silica-alumina, zeolites, clays, and mixtures thereof.
55. 55. A process for manufacturing ethylene including a first site and a second site, remote from each other, wherein the first site forms an olefinie Fiseher Tropsch naphtha to be used at the second site, the second site forming the ethylene, wherein the process comprises: a. receiving at the second site the olefinie Fiseher-Tropseh naphtha, which is made by a process comprising: i. converting a hydrocarbon asset to syngas; ii. subjecting the syngas to Fiseher-Tropsch synthesis to form hydrocarbonaceous products; iii. isolating the olefinic Fischer-Tropsch naphtha from the hydrocarbonaceous products; - 30 b. converting the olefinic naphtha in a naphtha cracker to a product stream comprising ethylene; and c. isolating ethylene from the product stream of the naphtha cracker.
56. 56. A process according to claim 55, wherein the olefnic naphtha has a total acid number of less than 1.5.
57. 57. A process according to claim 55, wherein the process to make the olefinic Fischer-Tropsch naphtha further comprises the step of purifying the olefinic naphtha to reduce the dissolved solids and acids therein to provide a purified naphtha.
58. 58. A process according to claim 57, wherein the purified naphtha has a total acid number of less than 0.5.
59. 59. A process according to claim 57, wherein the purifying is performed by contacting the olefinic naphtha with a metal oxide at elevated temperatures.
60. 60. A process according to claim 57, wherein the metal oxide is selected from the group consisting of alumina, silica, silica-alumina, zeolitcs, clays, and mixtures thereof.
61. 61. A process according to claim 58, wherein the olefinic naphtha comprises 50 to weight percent olefins and 20 to 50 weight percent nonolefins, wherein the non-olefins comprise greater than 50 weight percent paraffins.
62. 62. A process according to claim 55, further comprising the step of blending the olefinic naphtha with a naphtha selected from the group consisting of a hydrotreated Fischer-Tropsch derived naphtha, a hydrocracked Fischer Tropsch derived naphtha, a hydrotreated petroleum derived naphtha, a hydrocracked petroleum derived naphtha, and combinations thereof to provide a blended naphtha and converting the blended naphtha in the naphtha cracker.
63. 63. 1\ process of producing an olefinic naphtha comprising: a. converting at least a portion of a hydrocarbon asset to synthesis gas; b. converting at least a portion of the synthesis gas to a hydrocarbon stream in a Fischer Tropsch process unit; c. isolating an olefinic naphtha from the hydrocarbon stream, wherein the olefinic naphtha comprises 10 to 80 weight % olefins and 20 to 90 weight % non-olefins, wherein the non- olefins comprise greater than weight % paraffins; - 31 d. purifying the olefinic naphtha by contacting the olefinic naphtha with a metal oxide at elevated temperatures; and e. isolating a purified olefinic naphtha having a total acid number of less than 1.5.
64. 64. A process according to claim 63, wherein the metal oxide is selected from the group consisting of alumina, silica, silica-alumina, zeolites, clays, and mixtures thereof.
65. 65. A process according to claim 63, further comprising the step of separating water and carbon dioxide formed in the purifying step from the purified olefinic naphtha.
66. 66. A process according to claim 63, wherein the purifying step reduces the content of solids, acids, and alcohols in the olefinic naphtha.
67. 67. A process according to claim 63, wherein the purified naphtha isolated has a total acid number of less than 0.5.
68. 68. A process according to claim 64, wherein the purifying step is performed by passing the oleEmic naphtha through a purification unit containing a metal oxide at 450 to 800 F, less than 1000 psi", and 0.25 to 10 LHSV without added gaseous components.
69. 69. A product produced by the process of any one of claims 9 to 22.
70. 70. A product according to claim 69 which is a lower olefin product.
71. 71. A product according to claim 69 which is olcfnic naphtha.
72. 72. A product according to claim 69 which is ethylene.
73. 73. A product according to claim 69 which is a blended naphtha.
74. 74. A olehmic naphtha substantially as hereinbeforc described, with reference to the accompanying drawing.
75. 75. A blended naphtha substantially as hereinbefore described, with reference to the accompanying drawing.
76. 76. A process for producing lower olefins substantially as hereinbefore described, with reference to the accompanying drawing.
77. 77. A process for producing ethylene substantially as hereinbefore described, with reference to the accompanying drawing.
78. 78. A process for producing an olefinic naphtha substantially as hereinbefore described, with reference to the accompanying drawing. - 32
79. 79. A process for producing a blended naphtha substantially as hereinbefore described, with reference to the accompanying drawing. s