GB2408747A

GB2408747A - Process for production of lower olefins

Info

Publication number: GB2408747A
Application number: GB0505172A
Authority: GB
Inventors: Dennis J O'rear; Guan Dao Lei
Original assignee: Chevron USA Inc
Current assignee: Chevron USA Inc
Priority date: 2003-01-31
Filing date: 2004-01-23
Publication date: 2005-06-08
Anticipated expiration: 2024-01-23
Also published as: GB2408746B; GB2408747B; GB2408746A; GB0505171D0; GB0505172D0

Abstract

A process for producing lower olefins comprises a) converting a hydrocarbon asset to syngas; b) converting said syngas to an olefinic naphtha using a Fischer-Tropsch process; c) converting a portion of said naphtha in a naphtha cracker to produce a lower olefin stream; and d) recovering a portion of said lower olefins. Another disclosure relates to the production of ethylene from an olefinic naphtha. A further disclosure relates to a process for manufacturing ethylene, wherein an olefinic naphtha is formed by a Fischer-Tropsch process at one site, and the cracked at a second site to produce ethylene.

Description

lli',h Purity Olefinic Naphthas for the Production of F,thylcnc anal

lrOIJYknC CR()SS-I{F,1,1'1-1,D,NI'l'l,l(lATl()N'S I he Present aplcaton fix related k' 11 S. Patent. Al]caton No. 1()/3 55 1 1 () (Docket No ()() 5')5()-824) cntticcl '111 I'ty ()Ichu1c Naphtlas lortilc l:'rorlrcto ol l. tlylee alert l'rolylcnc''ncl I, i\tcnt,llcalron No 1()/354,')57 (I)ochct No ()()5')5()-X25) ctticci "1:1r '1 I'rrty ()Icfrc N.:llls Ic talc I'-i>clcto:f I<.tlylcic.1 1'- 1ylcc'lll ol lcl 1 0;-c I rIccl lice cwtl 11'1F,131) (-11-4''1'1114', INVI4 X I ION I lies lvclo1 r-eltes to paved LCCI111ICILICS Cot- pocilicill:, lo\vel- offs llolil Hall purty olelnc <ipltilas More.specfcally thc nvenin' rclaLcs to a roccss lor coivcrtn, an cxpcxve 1ytrocarl:(: resorcc Iro a r en(.tc locato nto hn=,l pcnty olkflc rapltla, lransportng tile olefnc apllila to a sccont f.aclty, ,act srlseqctly procexx the olefinc :apltila to prolrce lowor olel;n.s B.('KGR()U1ND ()1 rl-lr INVEN'rlON I. owor oleflils, n partclar olelns 1lavmg tl-on1 2 to 4 carbon ators, are xulabie star-trn;, n1ateraaix n a large nrnber ol clenncal processes, nclcdng, for cxan1pic, allylatro, oligoneri/.atro, and polyn1erzaton processes. Tl1e preparatror1 of lower olefins tion1 a hydrocarbon feed ly crackng of that Iced rs a well-known process and s connereally a,oplred al a large nunrber ot petroel1eneal manulaelurng, facilties rl ypeally, a dstillatc fi-aeton of a crude orl, eornnonly a napl1tila fraction of the crude orl, s sed as tlie hydrocarlon fecct n a naphtha eraeker process to produce ethylene lor comriercal reax-s, there x a demand for a napStha erachrl;, process havi1, a Ingh seleetvty for lower olet;ls, n particular etilylene. lilere is also a ctemand to n1anfactrc ethyler1c fron1 hydrocarilon assets otl1er than pciroleun 1aphtlas, cspecally 01CS lhat cosl less and arc n1or-e abunclant. Examples of sucl1 hydrocarbon assets inclcle natural as, coal, ancl heavy ols fornct n abndant spply U1 locatons that are r enotc Iron1 the etlylene markets (:lurrently there are two appioaches to cor1vertrn' rcmotc Irydrocarilon assets to ethylene wlere the ethyler1c rs mar1ufactured n developed locatons The first approach Is to convert a hydrocarbon asset obtained at a remote site Into a highly paraff'inic 1'ecd by a Fscher-'liropscl1 process. This apyroacl1 nvolvcs converting the hydroca.rhon asset into syntl1ess gas by partial oxidation and convcrtng talc synthcss gas into a mixture of hydrocarbons by a Fschcr-rl'ropscl1 process. A lydrocarbon liacton front the I;sclcrTropscl process may he used as a feed to a nap]1tlla cracking process to produce etlylenc By way of cxamplc, L-,iropcan Patent Application No. 1617()5 c:1iscloses that a fraction of talc product ova Fisclcr-Tropscl1 syntlless process nay be used as a hydrocarbon aced a napltlla cracking process. E1' 161705 dscloscs tsnb a (, fraction Groin the l<'iscler-'l.'r. 'pscl1 process, wherein tile Cal, laction substantially consists of lancer paraffins, as a feed for a naphtha cracking process 1513 1617()5 further discloses that. by using this feed, the selectivity toward lower olel'ins Is ncreasef conparcd with a napltla fraction of'a crude oil.

I'o mcreasc the sclectvty of' the napltha cracking process, a liglly paral'fir-nc Insclc I'ropscl naphtha that ilas been l-ocessed Using hydrogen, ncludn1b hydrotreatng, hydrocrackng, and hydrosonerizaton Is typically userl. To produce the ethylene, the h,hly paral'linc l;ischer'T'ropsel1 napl1t}la Is typically shipped front the SiLC whCrc syntl1eszed to a developecl site and converted Into ethylene no a i, phyla cracker.

By way of entangle, "Perfornance of the SASOI, Sl'l) Naphtha as Sloan Cracking l;eedstock", by l,urs P. Dancuart, et al., ACS 2002 National Meeting, Boston Mass, August 18 22, 9()()2, A(.S Preprints July 2()()2, and tJ.S Patent No. 5,371,3()S descrhe examples of this approach. U S. Patent No. 5,371,3()S teaches a process for preparing lower oleiins l'ron1 a hydrocarbon feed conprsn a hydroprocessed syntl1etc oil fractions wherein the hydrocarbon feed comprising the hydroprocessed synthetic oil fraeton is cracked. 'I'he lydroprocessed synthete oil l;aetion is derived from a synthesis process, such as a Fscher-Tropsci1 synthesis process and is subsequently treated n1 a process In the presence of hydrogen.

'I'he second approach for convertn, a remote hydTocaThon asset alto ethylene involves t}iC production ol niCthaTlol 'I'his approach Involves converting the hydrocarbon asset obtained at a remote site Into synthesis gas by partial oxidation and converting the synthesis gas Al a mCtilanol synthesis plant into n1etllanol. 'l'he netl1anol is typically shipped to a developed site and conveT-tecl into ethylene by a Methanol-to-OleI;ns process. 'the methariol to olelins process uses a mc-'leeular sieve to dehydrate and convert the mcthar1ol to a mixture of ethylene, propylene and other olefiT1s There are advantages to Using the process involving Fiseher-Tropsel1 naphtha to produce ethylene in comparison to the methanol process. Idlest acivantages Delude that the process involving l; seher-Tropseh naphtha can use existing conventional aphtlla eraelers.

Also, the highly paraffnTc napllllla produced In this process consists ol a lxtr.re ol nomlal and iso-paraflins with few cyclic compounds (aromates and naphthenes) I his hilly paraffinTe naphtha. provides higher yields ol etllyleie and lower colcng rates than typical pcLrr.leun naplltllas.

Ikwever, there are certain disadvantages of the process Involving use of l;scher l ropscl1 naplltha. l he disadvantages nclde the Ogle cost of converting, nethane silo Reilly paraffinc naphtha. One element of this high cost is the hydrogen that is typically needed to hydroLreat the Fischer-Tropscil products k' provide the highly paraifinc napUtlia. In addition, the ethylene cr-ackng step Involves a high temperature cndot} lennc reaction to deLydrogenate and crack the naptha Inks smeller li-a;, rncnts. '-I'hs high tcniperature enclotlcnTlc reaction require the rise of a s:,nficant amount of costly fuel '1'he approach nvolvin,, methanol synthesis may recluire 1'cwer Stops, but n] general the OnOnTICS of methanol production frorTl nattirAl gas are nor. In addition, wlcn ncthanol Is shipped, it must be renenl.cred that approxnalcly 5() Wttgo of the methanol is converted HltO water during the Methanol-to-Olcfins step. Thus, approximately twice the amount of methanol must he shipped in comparisons to a parafl'inc napiltha Furthcrnore, since methanol is toxic, it Is typically shipped n1 small specialty tankers at higher costs than those nccdcd for paraflrnc napl1thas. Finally, this approach requires the construction of new facilities for the Mctl1anol-to-Olcfins step.

There Is a demand for economical and efficient processes to convert Inexpensive hydrocarbon assets (such as n1cthanc or coal from remote sites) to ethylene in developed locations. It Is desired that lLcse processes have ccrlam advar1tagcs. It Is desired that the neutral COnVerSOrl of the hydrocarbon asset to the feed for talc naphtha cracDcrbe economical It Is desrabic that: the feed give high yields of ethylene thus rcqananb a smaller amount of feed neutrally It Is desn-abic that talc naphtha cracicng step have knew operatnig costs It Is desrabic that the overall process be con1patble with cxstn1g f'acltes, n1cludng, for example, ships, tanks, pumps, napl1tila crackers, etc

SUMMARY OF TTIE INVENTION

The present nventoT1 relates to techniques for proclueng lower oleLns from higl1 purity olefine napl1thas. In one aspect the present invention relates to a process for produen1g lower olefins. 'Idle process comprises eoT1veTtn1g at least a portion of a hydrocarbon asset to synthesis gas, and conVcrtiTlg at least a portion of the syntl1ess gas to an olefTe naphtha by a i;seler-Tropseh process. lit least a portion of the olefine naphtha Is eonvertecl ITI a napl1tila cracker to a prociaet stream eonprsing lower oleUns, and at least a portion of the low olef us From the produce st,-ean1 ol'the naphtha eraeicer are recovered.

In anotiler aspect the present niVcntioTl relates to a process for pTocluerIg ethylene 'I'he process ComprSCS converting at least a portion of a hydrocarbons asset to syntless as, and convcrtUng at least a portion ofthe synthesis gas to a hydrocarbon strcani in a Fischer-'l'ropscli process unit An Cleric napUtila from tile hycirocarbon stream Is Isolated, wherein the olelinc naphtha comprises 25 to S() weight t/, platens and 20 to 75 weight (470 non-oleUns, when the non-olefns comprise greater than 75 Wei,i1t ':g, paraffins rl'he olelinie naphtha Is purified ITI the presence of a natal oxide to proves a pu-ilied olefine naptha having a total acid nun her ol'Iess than 1 5, and at least a portion <-'f'the purilec' olefn1c naphtha Is eonveT-led no a naphtha cracker to a procl'et stream ecmprsing ethylene. At least a portion of the ethylene front the product stream ol'the naphtha eraekeT- Is recovered.

In a further aspect, the present invention relates to a process for manufaeturmg ethylene Including a I-irst site and a second site, remote front each otler, wherein the first site forms an olef'hle IuseheTrl'ropsel1 napiltha to be used at the second site, the second site fondling the ethylene She process comprises receiving at the second site the olef'inc FscheT--'lropscil naphtha, eonvertng the clef rile naphtha in a naphtha craelcer to a product stream comprising ethylene, and Isolat1Tlg ethylene item the pi oduct stream of the napiltila eraser. In this process the olefine Eischer--l'ropscl1 naphtha is made by a process eoTIprisTlg eoTlvertng a hydrocarbon asset to syngas, subjecting the syngas to Fscher-Tropsc}1 syntiless to form hydroearbonaeeots products, and isolating the olet'he Fseher-rl'ropsel1 naphtha Prom the hydroearbonaeeous products In yet another aspect, the present invention relates to an olefine napl1tila. The clef nic naphtha comprises (a) olefins In an amount of 10 to 80 WCig}lt '/O, (b) noT1-olefins in an amount of 20 to 90 weight /,, wherein the non-olefns comprise greater than 50 weight /O paral'lins, (c) sul tar m an amount ol'less thaTI 0 ppm by weight, (d) nitT-oge,I In an amount of less than I O ppm by weight, (e) aromatics nil an amount less than I O weight %, (f) a total acid number of less 1 5, and (g) a boiling range of Cal to 4()0 ln Tle present invention also relates to an olef'imc naplrtlla comprising (a) olcfins n1 an amount of 25 to 80 weight /0, wllerem tlic olefins arc comprised of greater than 65 weight 'hi, linear primary olefins, (b) n-'n-olcHns no an amount of 2() to 75 wcght /0, wllercnl the on- olefins comprise grrcater thar1 75 wcght '/, paraffins and the paral'fins have an i/n ratio of less than 1, (c) slur in an amount ol less than 2 ppm by weight, (d) nitrogen in an amount ol'less than 2 ppm by wegllt, (c) aromatics n1 an amount less than 2 weight 'l/0, (f) a total acid numUcr of less 1 5, and (g) a boiling, range of Cal to 400 E;'.

In another- aspect, the pr CSCnt mvcnton relates to a process of'producn1g an olcfimc naphtha. 'I'he process conprscs converting at least a portion of a hydrocarbon asset to syOlllesis gas, and conVertmg at least a portion ol'the synthesis gas to a hydrocarbon str-earn no a Fscher-'l'ropscl1 process unit. An olei'inc naphtha Is isolated fi-oni the hydrocarbon stream, whereat the oletnc naphtha comprises I () to 80 weight 'hi, -'lelins and 2() to 9() weight 'hi, non oleCins, wlleren the n<-n-olefhs compr-se greater than 5() weight'>/0 par-afl'hls 'I'he olel'inic naphtha Is portlier lay contacting the olelinc naphtha with a metal oxide a elevated temperattres, and a pur-l'ied olefinc naphtha having a Stat acid number of less than 1.5 is isolated In yet another aspect, the present inventions relates to a blended napl1tlla. 'I'he blended naphtha comprises (a) an oleEinc napl1tlla comprising I () to 80 weight OX, omens and 20 to 9() Weigilt a/, non-olefns, wherein the non- olel'ins comprise greater than 5() weight SO paraffins and (h) a naphtha selected fi-om the group consisting oI'a hydrotreated Fscher-Tropsch derived naphtha, a hydrocracked l*sche-'l'ropsch clerked naphtha, a hydrotrcated petroleum derived naphtha, a hydrocraciccl petroleum derived napl1tlla, and mxttues thereof. 'Lyle blended naphtha comprises less than 10 ppn sulkier and has an acid Hunker of less than 1.5 In a further aspect, the present n1venton relates to a process for prodtcing a blended naphtha. The process comprises convcrthg at least a portion ol'a hydrocarbon asset to synthcss gas and converting at least a portion of the syntl1ess gas to a hydrocarbon stream in a Ischer-'l'ropsch reactor. An olefimc napl1t}la Is Isolated wherein the olef'inic naphtha comprises 10 to 80 weight SO o}efins and 20 to 90 weight </0 non-olefins, wherein the non oleUn1s comprise greater than 50 weight A, paraffins. The olefinic naphtha is mixed Wits a naphtha selected from the group consisting of a hydrocracked Fischer-Tropsch derived naplltlla, a hydrotreatcd l;'scller-Tropsch derived naplltha, a hydrocracked petroleum derived naphtlla, a hydrotrcatcd petroleum derived naphtha, and mixtures thereof to provide a blended naphtha The blended naphtha comprises less than 1 () ppM1 sulfur and has an acid number of less than 1.5.

In yet a further aspect, the present invention relates to a process for producing a blende<l nal?htlla. The process comprises providing an olefnic ncZpEtha comprising 10 to 80 weight /0 olefins and 2() to 90 weight % non-olefins, wherein the non-olefns compose greater than 50 weight A, paraffins. 'l'hc olefinic naphtha is mixed with a naphtha selected fi-on1 the group consisting of a hyclrocracke<l F'scller-'ltropscl dcrved naplltlla, a hydotreated Fscler- I'ropsch dcrvcd naphtha, a hydrocracked petrolcun dervcd napllilla, a hydrotreated pctroleun dcrvetl naphtha, and mixtures thereof Lo provide a blended naphtha. 'I'he blended naphtha comprises less than 10 ppm sulfur and has an acid number of less than 1.5.

1 5 BRIEF DF,SCRIPrl'lON OF THE, DRAWINGS I'hc Figure Is an illustration of a process for converlng natural gas to eth' acne with co producton of 'tller salable products.

1)F,TAII,ED DIISCRIPTION OF THE II,l,USTRATlVII F,MIlODIMF,NTS The present nlventlon relates to an olefinlc naphtha and a process for producing lower olefns from this olef'inic naphtha.

D,fi'to's The following terms will be used throughout the specification and will have the following mcanmgs unless otherwise mdlcatcd.

Tile tem1 "naphtha" means a hydrocarbonaceous mixture containing compounds bOlllNg bCtWcCn C5 and 400 1-. The Cs analysis Is performed by gas chromatography, and the 400 F temperature refers to the 95% boiling pout as measured by ASTM D- 2887. Preferably, at least 65% of the hydocarbonaceous mixture bolls bctwcen C: and 4()() F, most preferably at least 85''/o.

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

The tend "olcfins" means an unsaturated straight or branched chain hydrocarbon having at least one double bond (he., an alkcne).

Tlle tend "olefinic naplltha" meaTls a naphtha containing 10 to 80 wt% olchins and 20 to '30 wt '/0 non-olefins, wheren1 the non-olefins contain predominantly paraffins. Preferably, olefimc naphtha contains greater than or equal to 25 k' S() wt'/, olcfiTls, and more preferably SO to 80 wt % olefins. Preferably the non-olefins of the olcfinic naphtha comprise greater than 50 wt% paraffins, more prel'crably greater than 75 wt % paraffrls, and even more preferably grcatcT- than 90 wt /0 paraffins (weight /0 are based on the non-olefin component). Prcfcrably, the olcfinc naphtha also contains less than 1 () ppn1 stiller and less than 10 ppm nitrogen, told more preferably both sulfur and nitrogen arc less than 5 ppm, more preferably less than 2 pan, and even more preferably less titan I ppm. Preferably the olcfnic naphtha contains less than 1 () wt'/o aromatics, more preferably less than 5 wt'/, aromatics, and even more preferably less than 2 wt'l/o aroniatcs. OleDms and aronatcs are prctcrably measured by SCI'(:' (Supercrtcal l'<lud Chromatography).

The term "lower olci'ins" means olefins having from 2 to 4 carbons. Prcf'erab]y lower olcfins refer to ethy]cne and prop, 'ene, more pTefcrably cthylcnc.

I'he tern1 "hnear Nary olefins" nears a straglZt chain 1 -alkene, commonly known as apply o]efins I'he tend "tote] acid number" or "acid value" Is a measurement of acidity. It Is determined by the number of mTlligraT1ls of potassium hydroxide required for the neutralization o ['acids present n1 I grant of the sample bemg measured (ma KOH/g), as measured by ASTM 1) GG4 or a suitable equivalent. The olefimc naphtha used in the processes of the present Invention preferably have a total acid number of less than 1.5 m;, KOH/g and mote lret'erably less than 0.5 mg KOH/g The tenn "oxygenates" means a hydrocarbon contammg oxygen, i.c., an oxygenated hydrocarbon. Oxygenates include alcohols, ethers, carboxylc acids' esters, ketones, and aldeLydes, and tle like The iem1 On ratio" means isoparaffin/normal paral'lin weight ratio. It Is the ratio of'thc total number of iso-paraffins (he., branched) to the tote] number of norrllal-paraff its (he., straight cham) in a given sarnplc.

The term "clerved from a Fischer-Tropsch process" or "FTscher-Tropseh derived" meaT1s that the product, fraction, or feed originates from or is produced at some stage by a Fscher-'l'ropscl1 process.

al he term "derived from a petroleum" or "petroleum denved" means that the product, fraction, or feed originates from the vapor overhead streams fiom distTlhTlg petroleum crude Gild the residual fuels that are the nc-, n-vaporzable remanng portion. A soiree of the pelroleum-deTvecl can be from a gas field condensate.

The ten11 "hydrotreated Fischer- l ropsch derived napllt}Ta'' means a naphtha that is derived frown hydrotreatng a C: to 4()() F cording Fischer- I ropscl1 product.

The term "hydroeracked luscller-Tropseh derived napl1tlla" means a naphtha that is derived Font hyclrocrackTng a 4()() F+ containing ITscher-Tropsch product The terra "lydrocracked petT-oleun clerved nal:'htlla'' means a napttlla tl1at is clerved front hydrocrackng 40() F containing petroleuTll derived products.

I'he term "hydrotreated pctroleun1 clerved naphtha" means a naphtha that is derived Font hyclrotreatmg a C5 to 4()0 F containing petroleums derived product The tern1 "elevated temperature" n,eans temperatures greater than 2()"C. In the process of the present nveTItTon, elevated tenperatuTes, with reference to the puT-fcation of the olefinc napllthas, are preferably greater than 450"F.

It has been surpnsngly discovered that an olefiTIic naphtha produced fron1 a Fscher Tropsch process, rather than a paraffnic naphtha, provides certain advantages For example, the costs associated with prodtcing the olcfinic naphtha are reduced because a hydroprocessing step, and thus expensive hydrogen, Is not required to manufacture the olefimc naphtha. In acldition, when the olefinc napl1tlla is used to make lower olefins, for example ethylene, the yields of ethylene are ncrcased because olefins provide higher ethylene yields than paraffins. 'l'herefore, the amount of feed to a naphtha cracker to produce a desired quantity of ethylene is less when using an olefin teed in comparison to a 1:araftin feed.

E<urthennore, the operating costs for the naphtha cracker are reduced because the heat of conversion requirements of olefins to ethylene are less than for the corresponding 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 n1vcntion relates to an olefnic naphtha. The olefinic naphtha of the present invention is made by a Fischcr-Tropsch process.

In the Fscher-Tropsch synthesis process, liquid and gaseous hydrocarbons are formed by contacts;, a syntlless gas (syngas) comprising a mixture ol'I-I2 and CO with a Fiscler- Tropsch catalyst under suitable temperature and pressure r eactive conditions. 'I'le Fscher-Tropscl1 reaction is typically conflicted at temperatures ol'ahout from 30() to 7()() 1; (149 to 371''C) preEcrably about from 4()() to 550 1. (204 to 228"C); pressures of about from to GO() psych, (0.7 to 41 bars) preferably 30 to 3()() pea, (2 to 21 bars) and catalyst space velocities of about fi om 1 ()() to 1(),0()() cc/g/lr., prei'crably 3()() to 3,00() cc/g/hr.

'I'he products allay range from Cal k' Cow with a maJonty In the Cs-C range. Tile reaction can be conducted in a variety of reactor types for example, fixed bed reactors contanub one or more catalyst beds, slurry reactors, lludized bed reactors, or a combination of dif'i'erent type reactors. Such reaction processes arid reactors are well known and locunentecl In the htcraturc Slurry lischer-'l'ropsch processes, whelk Is a prefen-ecl process n tle practice ol'tlie nverltiorl, utilize superior heat (and mass) transl'er characteristics for the strongly exothermre synthesis reaction and are abl, to produce relatively high molecular weight, parafl'ime hydrocarbons when using a cobalt catalyst. In a slurry process, a syngas eomprsnig a mixture of E-12 and CO is bubbled up as a third phase through a slurry In a reactor wlliell comprises a particulate l seher-Tropsel1 type hydrocarbon synthesis catalyst dispersed and suspended in a slurry liquid eomprsiTIg hydrocarbon products of the synthesis reason which are Equal at the reaction conditions. The mole ratio of the hydrogen to the carbon monoxide may broadly range from about () 5 to 4, but is more typically within the range of from about 0.7 to 2. 75 and preferably from about 0.7 to 2.5. A particularly prel'eTed Fischer Tropseh process is taugl1t n1 EP06()9079.

Suitable L'seher-'I'ropsel1 catalysts comprise on or more Group Vlll catalyte metals such as Fe, Nil, Co, Ru and Re. Additionally, a suitable catalyst Nay contain a promoter.

Thus, a preferred Fscher-r['ropsch catalyst comprises effective amounts of cobalt and one or more of Re, Ru, Pt. I'e, Ni, 'l'h, Zr, Hf. IJ, Mg and La on a suitable n1organic support material, preferably one which comprises one or more refractory metal oxi:les In general, the amount of cobalt present in the catalyst Is between about l and about 50 weight percent of the total catalyst composition. The catalysts can also contain basic oxide promoters such as ThO2, Lagos, MgO, and Tub, promoters such as ZrO2, noble metals (fit, Pd. Ru, Rh, Os, Ir), coinage metals (Cu. Ag, Au), and other transition metals such as Fe, Mn, Ni, and Re Support materials including alumina, silica, magnesia and titania or mixtures thereof may be used.

Preferred supports for cobalt containing catalysts comprise ttana IJseful catalysts and their preparation are Known and Illustrative, but nonlrnitir1g examples may be found, for example, In U.S. Teal Nos. 4,568, 6(53.

The products from Fscher-rl'ropscl1 reactions perfon1lcd In slurry bed reactors generally include a light reaction product and a waxy reaction product. rl'he light reaction product (i.e. the condensate fraction) Includes hycIrocar-bor1s bong below about 700"F (e.g., tall gases throtigl middle distillates), largely n1 the Cs-C2> range, wills decreasing amounts up to about C30 'I'he waxy reaction product (he. the wax fraction) nclucles hydrocarbons holing above about G()() F (c.g, vacuun1 gas oil through heavy paraffins), largely in the C- range, wetly decreasing anoints down to Call. Bc>Ll1 the hght reaction product and the waxy product are substantially paraf]'inc. 'I kc waxy product generally comprises greater than 7()/O nonnal paraffins, arid oi'ten greater- tllan 8()/o normal paraffins. 'I'he light reaction product comprises paral'linc proclticts with a significant proportion of alcohols and olet'ins. In some eases, the ]rg]n reaction product may comprise as much as 5() Y,, and en en higher, alcohols and olefir1s.

:he olefinrc naphtha of the present u1vention nary be Isolated from the products oI'the products of the Fischcr-Tropsch process by distillation. 'lithe olefinc naphtha of the present n1ventoi1 bo]s between C5 to 4()() F.

In the process ofthe present n1venton, the olct'inc naphtha may be purl fed Oletinc naphtha from Fscher-'Lropsc]1 fac]tes f'requcnt]y contain impuntes that should be removed, but without saturation of the o]elns. Examples of these mpuntc,s nc]udc acids and heavy metals. The acids pr csent In Fischer-'L'ropscl1 naphtl1as are corrosvc and will rapidly attack rectal suri'accs in ships, tanks, pumps, and the naphtha cracker. Since the acids attack mcta]s, the metals will become n1corporatcd n1to the na}:,l1tlla and lead to ncrcased foahr1g of furnace tribes In downstream processors, including for cxan1ple, a napl1tlla cracker. In addition, metals can be n1corporatcd Into the naphtha by direct reaction of the acids with typical t<'ischer I'ropscl1 catalysts - e.g Iron. Therefore, it may be necessary to remove the acids and dissolved n1eta]s present in the olcfinrc naphtha by a process that can do so without saturating the olefins.

Alcohols and other oxygenates may also be present in the oleLmc naphtha from the Fischer-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 yrocessmg conventional petroleum, it is standard that crude oils shoiilcl have total actual members less than 0.5 mg KOII/g in order to avoid corrosion probieril. It Is further standard that distillate fractions have acid numbers less than 1.5 mitt KOH/g. See, "Materials Sclecton for Petroleum Refineries and Gathering Fachtes", Richard A. White, NACE lnten1atonal, 1'998 1 louston Texas pages 6-9 rl'herCfore, the purif'icaton pTOCL'SSCS of the present mventon for the oleDmic naphtha are capable o f pTovidn1g an olefime napUtila with a total held number yrel'erably less than 1.5 mg KOI-I/g, rnor-e preferably less than l.() mg KOI-I/b, and even more pr-el:'erably less than 0.5 nag KO}I/g, without appreciably saturating the olefins contained therein. 'lithe olefinie naphtlia solatecl Sweetly from the Fscher-'l'rolisch process may have an acceptable total acid number However, Fire oleCh1c nalilitila solat::cl does not have an acccptahie total acid number, it will be necessary to purify it as described fierce hl tl-! conventional technology that produces a highly paraff' He naplitha, mipuratLs, inclrdm=T Decals, alccl1ols, and other oxygenates, are removed by a hydroprocessing techniqtc, for example, hydrotreatmg, hydrocracking, hydroisomerizaton etc. I lowever, these processes also simultaneously convert the desirable olefins into relatively less clesrabic paraffins.

According to the present mventon, the acids anti dissolved metals in Fischer-'l'ropsch napiltilas are removed by contacting the naphtha with a metal oxdc catalyst at elevated temperatures. In contacting the naphtha with the metal oxide at elevated temperatures, acids arc converted mto paraffins and olefins by decarboxylaton. In addition, alcohols arc converted into additional olefins by deLyciration, and other oxybcnatcs (including ethers, esters, and aldehydes 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 desired (to Improve catalyst/napl1tha contacting or for heat control). The oxygen m the nayl1tila Is converted mto water and carbon dioxide. which can costly be separated fi-om the product olefinic napiltha.

If dissolved metals are present In the naphtha, they will be simultaneously removed and deposited Oil the metal oxide catalyst. Typically, the metal oxide catalysts used in the purification process according to the present invention will show low deactivation rates; -1 1 however, eventually the catalysts will riced to be r cgcnerated or replaced. Regeneration of the catalysts can be accomplished by stripping with a higil temperature gas (hydrogen or other), or by burning the catalyst while it is In contact with an oxygen containing gas at cicvatcd temperatures. RcgcncratioTI by burning is preferred. I'referably the purficatol according to the present Invention Is performed

by passing the olefinic napiltha through a purification unit contamng a metal oxide under conditions of 450 to 8()() F, less than 1000 psg, and 0 25 to 1 () 1,T]SV without added gaseous components By way of cxampic, the purl iicaton process nary he pcrlornicd by passing the olelinc naphtha downftow tilrough a purification unit containing a metal oxdc at elevated temperatures.

Preferably, tile metal oxide is selected from the group conssthig of alumina, silica, shca-alumna, zeolites, clays, and nnxtures thereof. Sncc tcmnnal oilcans arc belevcd to give the highest yicid of cthylcnc, it Is prcicrabic to select an oxide that Is effective for dellydraton of the oxygenates, yet does not promol:e somenzaton calf the olelins from their tcmlinal position to ntcrnal or branched olefins. On this basis, a preferred metal oxide Is alumina Additional consonants can be added to the metal oxide to promote the dchydraton or retard olefin somcrzaton Examples of such additional conponcnts arc basic elements such as Group l or lI elements of the Melodic table. 'l'hcsc basic components can also retard catalyst fouling. Usually these components arc incorporated Into the oxide forth In the fnisl1ed catalyst.

The severity of tile publication process can be varied as necessary to achieve the desired total acid number. 'I'ypcally the severity of the process is varied by adjusting the temperature, and l,l-ISV. Accordingly, a more severe purification may be accomplished by r tinning the purlicaton process at a hgler tempcraturc, and under these more severe purification conditions more oxygenates will be removed, thus provdmg an olefinic napl1tlla with a lower total acid number.

Tl1e purilicaton processes of the present nventioil provide an -,lefnic naphtha with a total acid number preferably less than l.5 mg KOH/g, more preferably less than l 0 mg TCOH/g, and cVcn more preferably less than 0. 5 mg KOET/g, without saturating the olelins contained thcrcn. The purification processes of the present nvcnton prct'crahly remove more than 80 weight percent of the oxygenates in the olefinic naphtha.

The olcfinc naphtha according to the present invention is a naphtha containing 10 to 8() Wt% olefins and 20 to 90 wt % non-olefins, wherein the non-olefins contain predominantly parafl'ins. PrcLerably, olcDmic naphtha contains greater than or equal to 25 to 80 wt% olefins, and more preferably 50 to 8() wt "hi, olcfins. Tile olel'ins of the olef'inc naphtha are predominantly Linear primary olefins. E'rchcrab]y, the olefins compose greater than 50 wt % hnear primary olefins, more prcEcrably greater than 65 wt 'hi, hnear primary olefins, and even more preferably greater than 8() wt '3/0 linear primary olefins.

(he non-oleDnc component ot'the olcfimc napl1tlla is prcdomhantly parai'fnic.

Preferably the non-oleLn1s comprise greater than 5() wt /0 paraffins, mote preferably greater than 75 wt TO paraffins, and even more prcl'erably greater than 90 wt % paraffins (as measured OH the leases of the non-olef;nc conponcnt). 'I'hc paraffins of the non-olefinic component of the napl1tila are predominantly n-paraf'fins. E'rcferably the parai'fins have an i/n ratio of less than 1 (-) and snore preferably Iess than 0 5.

In a:ldton, preferably, the oleDnnc naphtha also contains Iess than 1() ppm sulfur and less than 1 () Spin nitrogen, and more prel'erably both sulfur and nitrogen are less than 5 Spin, n1OTC preferably Less than 2 Cam, and cVcn more preferably Iess and 1 pant. fiurtllern.ore, the olefinc naphtha prcherably costars Iess than] 0 we, aronatcs, more prel'erably Iess than 5 wt% aromatics, and even more preferably less than 2 wt X, aromatics. Cleans and aromatics are preferably measured by SCIiC (Sr.percrtical Fluid Chroniatograplly) The olefnc naphtha according to the present invention nay be blended to provide a blended naphtha tights blended naphtha may be used for any purpose for whacks a naphtha is used These purposes Include processes for producing ethylene, including both traditional processes and the process of the present Invention. A blended naphtha comprises the clef nc naphtha as described above and a naphtha selected from the group consisting of a hydrotreated Fischcr-Tropscl1 derived naplltha, a hydrocracked Fischer-'l'ropsch naphtlla, a hydrotreated petroleum derived naphtha, a hydrocrackcd petroleum derived napl1tlla, and mixtures thereof'.

The blended olefinic naphtha according to the present rnver1ton Is made by a process comprising mixing an appropriate amount of an olefimc naphtha, as described herein, with anotl1cr naphtha selected fi-om the group, as defined above, to provide a blended napl1tlla. 'I'he olel'inc napttl1a 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 KOII/g. Also, preferably the blended naphtha also contains less than 1() 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 1 ppm. In addition, pret'erably the blended naphtha eomprses less than 10 weight TO aromatics, more prel'erably less than 5 weight TO aromatizes, and even more preferably less than 2 weight INTO aromatics.

I'he bonded napl:tha according to the present invention may Comprise varying amounts of olefne naphtha versus the other naphtha as defined above Preferably, the olefnc naphtha comprises 1() to 9() weight'/, olehnic naphtha and 90 to 10 weight TO other naphtha as defined above. More preferably a blended naphtha comprises 3() to 7() weight 'hi, clefs naphtha anti to 30 wc,ht % other naplltlla.

I'he olefine na.pltha of the present mventon provides a superior feed l'or a naphtha cracker for the proclueton of lower olefins. The process For proclucng lower olefns according to the present mventon comprises eonvertng at least a portion of'the olefie naphtha, as described above, al a naphtha cracker to a product stream conprisng lower olefins anal flower olefius are recovered from this product stream.

l'hennal cracking of hyclrocarb.ns is the principal route for the industrial production of ethylene Typical conditions tor Conducting thermal cracking to produce ethylene are desenlled m K.M. Sundaram, et al. , l:tlyle'e, Kirk-Otlner Encyclopedia of Chemical rl'echnology, April 1(', 2()01, herein incorporated by reference In its entirety. 'l'he thermal cracking reaction proceeds in pyrolysis coils of a radiant section ol'a l'urnaee. Since Solve is also formed during pyrolysis, steam is added as a diluent to the feed. rl'he steam mnnzes the side reaeton l'ormmg coke, and improves selectivity to produce the desired olefins by lowering hydrocarbon partial pressure. '1:'he temperature of the hydrocarbon and steam mixture entering the radiant chamber (lcnown as the crossover temperature) is 500 to 7()0"(.

Depending on the residence twine and required feed seventy, the coil outlet temperature Is typically mantanled between 775 anal 950"C' I'he combination of low residence time and low partial pressure produces high selectivity to olchms at a constant feed conversion. In the 1)60s, the residence time was ().S to 0.8 seconds, whereas in the late 1980s, residence time was typically 0.1 to 0 1 S seconds.

l'ypical pyrolysis heater characteristics are given In the below table.

Table. Pyrolysis Heater Characteritics Single heater- charactelistlc Range number of Bolls 2-17G coil lenglh,'n 9-80 inside coil diameter, non 30-200 process gas outlet temperature, C' 750-950 clean colt metal temperature, C 900-1,08 neat metal temperature, C I,() 40- 1,15() aver-age heat absorption, kW/n12 ext. are a 50-11() hulls residence tune, s O 1-() (I coil outlet pressure, k't'aa 150-275 clean coil pressure drop, kPa'i 10-200 I o ctnvet Ma to bar, dvdc by 100 Cracking rcactic-'ns are endotl,,ennic, I.G-2 8 M.l/kg (70()-12()() B'l'U/lt) of hydrocarbon converted, wetly heat supplied by i'irmg fuel gas and/or fuel oil in side-wall or. floor burnel-s.

Side-wall burners usually give uniform heat distribution, but the capacity ol'eael1 bunter is hated (0.1-1 MW) and hence 40 to 2()() hoers are required in a single furnace. W,th moder n floor burners, also called hearth bun,ers, uniform heat flux d'stnbution can be obtan1etl for coils as longly as 10 n1, and these are extensively used n1 newer designs. 'I'he capacity ol'these burners vary considerably (1 -I () MOO), and hence only a few burners are required. The selection of bunters dcpeads on the type of fuel (gas and/or liquid), source of eornbust'on air (ambleut, preheated, or gas turbine exhaust), and required NOX levels. The rcacto,l1 mixture exiting the furnace Is quickly cooled in quench coolers.

l Using the oleDnic naphtha, as described above, as the feed to a naphtha cracker increases tl,,c yields of ctl1ylene in comparison to paraffinic naphtha. The Improvement n1 yields of ethylene during napttl1a cracking can be understood by examl',1ln1g the chemistry of naphtla cracking. For a typical C, paraffin, the cracking reaction (without dehydrogenation) is as follows: C6H4 2C2H4 + C2H6 Accord',ngly, one n,,olc ol hcxanc gives two moles of ethylene and OIIC mole of ethane.

The reaction for the con esponding C6 olefin the reaction is as follows: C6II2 3C2H4 Since the oletin is hydrogen dcl:cient in comparison lo the paraffin, less low-valued ethane Is produced and the yield of desired ethylene potentially Increases by 5()"/,. llowever, under connnercal conditions a portion of j:1e starting hexaTIe would be dellydrogenatcd to for- hexene and hydrogen, thus increasing the actual yield of ethylene over what would be expected wtlout dehydrogenaton. Ncverthelcss, when olefinc fccds arc used, ethylene yaks are Increased over what is observed with tlc correspond paraffins. Accordingly, the cracking reaction of the present mvento is more Of Accent since it uses cu1 olefiic naphtha fccd, as dcscrbed above lurthcrmore, the cracking rcacLon of the present invention using an olefimc naphtha feed Is more ccononcal While both conversions of paraffins (I c., hexanc) and olefins (he, hexanc) to cthylcnc arc cndotlcnnc and thus require highly temperatrrcs, the conversion of olclins is less cndothemlic than tle conversion of paraffins because the eidotIlennc deLydro;,crlaton r-cacton does not occur to the same extort. Accordingly, thus energy consumption dur mg conversion of olcfnc naphtha to..thylenc Is dower than what would be expected for the corresponding paraffin. This lower energy consumption reduces the operatng cost oL'thc steam cracker.

It should be noted that current l'eedstocks used in naphtha crackers do not contain sgmficant amounts of olefins because they arc derived from petroleum, whacks is typically devoid of these compounds.

The processing of'an olefimc fcedstock In a napttlla cracker may result in an increase In the furnace tube coking rate. 1-Iowever, i f this happens, any one or combinations of the following actions may be taken to control this problem. 'I'hcse actions inclurie increasing the Iequency of'decokng operations, ir1creasng the I-12O/hydrocarbon feedstock ratio, adding sulfur or a sulfur-containing stream to the feedstock, and coating the reactor with a coke passvation agent such as tin, chromium, alummurn, germanium, and combinations thereof.

In the process of the present invention for producing lower olefns, at least a portion of a hydrocarbon asset is converted to synthesis gas. The hydrocarbon asset nary 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 olcfinic naphtha by a FischerTropsch process, as described above. The olcimic naphtha is isolated from the Fischcr-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 olefnc naphtha is converted In a naphtha cracker to a product stream cornpr-isng lower olefins and at least a portion of the lower olefiTls are recovered from the product stream. Preferably, these lower olefins comprise ethylene.

A preferred embodiment of the present invention is Illustrated m Figure I. In a location remote frond the ethylene manufacturing plant, netllale (10) Is mixed with oxygen and stean1 (neither shown) and reacted us a syr:lthess gas generator (2()) to come a synthesis gas stream (30). Tile synthesis gas is reacted In a slurry phase l<'Tscher-Tropsch unit (40) to produce a liquid phase product (5()) and a vapor- phase product (60). The vapor phase product Is separated to form a distillate range material (')() ) which contains Call and greater hydT-ocarhonaceous comllouTlds. Also produced no this separation Is an olefinic naphtha (()), which centers Cal to 4()() F hydrocarbonaceous conpouTIds. Tile olefinc naplit]a Is passed downflow tlrongl a pals-, I;cation unit ( 100) at 680"F, 5()pSTg, and 5 LL1SV without added gaseous conponerlts. 'file puT1fcaton unit contains alumma 'I'he purification Unit removes nlorc than 80'1/, of'tle oxygenated compounds, Increases the olefin content, and reduces the acidity I. f the oleiinic naplltlla. A purified olefinc nallhtlla Is produced ( 120) and shipped (140) to an ethylene manufacturing sits where it Is crachecd U] a naphtha cracker (]60) to produce an ethylene containing stream (17()). Salable, ethylene is recovered from the ethylene eontainng stream by steps not shown.

Meanwhile, the liquid phase product from the E<'scher-Tropsch l;acilty (5()), which contains 4()0 F I- material, Is blended with tile distillate range Lateral (9()) and the blond is processed in a hydrogenation facility (110) that converts the product mto salable products: diesel fuel, jet fuel, and/or lubricating on base stock (130). The hydrogenation facility consists of hydrocracking, hydrotreatmg, andlor hydroisomenz, ation steps These salable products are shipped (15()) to markets (180). Alternatively, parat'I;nc naphtha (not shown) produced In the hydrogenation facility ( I 10) along with other salable products can be blended with the purl fled oceanic naphtha (120) and shipped.

Tile optional pun location treatnent of the olefinic naphtha can be perfomlec:l either before shipping (as shown above) or after shipping and prior lo conversion in the steam cracker, or it can be performed at both locations.

EXAMPLES

The Invention will be further explanted by the following Illustrative examples that are Intended to be non-lmtinO.

Example 1: Fscher-Tropsel1 Olefinc Naphtl1as Two olefinic naphthas prepared by the Fischer-Tropsch process were obtained The first (Feedstock A) was prepared by use ova iron catalyst The second (Feedstock 13) was prepared by use ol'an cobalt catalyst. 'l'he 1<'scher-Tropscl1 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 contains sign f cant amounts of dssolvecl neon and Is also acidic. It has a significantly poorer corrosion rating.

I or purposes ot'ths Invention, Feedstock B is preferable. It contains lower oxygenates, has a lower acid content, and is less corrosive Thus it Is preferable to prepare olefinc naphtha for use no ethylene production Tom col:'alt catalysts rather than iron catalysts.

Naphtlia li-on cobalt catalysts nay have low enough levels of n11purtes that the naphtha may he able to be u ed without further treatment or purification, as describe l above.

A noodled version ot'AS'l'M D655() (Standard Test Method for the l') eten1lniation ot' the Olden Content of Gasolines by Supercritical Fluid ChromatOOrayl1y - Slog) was used to cletem1nle the group types in the tccdstocks and products. The modIied method is to quantify the total amount of saturates, aromatics, oxygenates and olcfins by making a 3point calibration standard. Calibration standard solutions were prepared using the following compounds: undecane, toluene, n-octanol and dodecene. F:xten1al standard method was used for chant fication and the detection limit for aromatics and oxygenates is 0.1"/, wt and for oleiins IS l.() tl/o wt Please refer to ASTM D6550 for n1strun1ent conditions.

A small ahquot of the Iuel sample was injected onto a set of two chron1atographc columns connected nil series and transported using supercritcal carbon doxdc as the mobile phase. The first column was packed with high surface area silica partclcs 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 cychc alkanes) pass through both columns to the detector, while the olefins are trapped on the silver- loaded column and the aromatics and oxygenates are retained on the silica column Aromatic compounds and oxygenates were subsequently elated from the silica column to the detector in a back Bush mode Finally, the olcfins were back flushed from the slver-loaded column to the detector.

A flame ionization detector (FID) was teased for qtantfcation (calibration was based on the area of tile ehromatographic signal of saturates, aromatics, oxygenates and omens, rclatve to standard reference n1aterals, whacks contain a letdown mass ''/, of total saturates, aromatics, oxygenates and olelins as corrected for density. rl'he total of all analyses was within 3'L'0 o l' I 00'', and normalized to 1 00/o for convent enee.

The weight percent clef ns can also he calculated from the bromine nun1her and the average molecular we,,hL by use ol the following forillla.

Wt g, Olehins - (bromine No.)(Average Molecular Weiglt)/159.8.

It Is prel'erabie to nicasure the average molecular weight directly by appropriate nethods' but it can also be estimated by Correlations using tl1e API gravity and nid-bolng ponds. as described n1 "1're:lcton of Molecular Weight ol'I'etroleu l'ractions" A G (,oossens, IE(I Res. 19'36, 35, p.985-')88.

Preferably the oief1s and other components are measured by the nodl' ad SFC method as described above A GCMS analysis of the feedstoeks determined that the saturates were almost exclusively n-parafI;ns, and the oxygenates were predominantly primary alcohols, and the olefins were predonn1antly primary linear oleEms (alpha olefns).

I'xample 2 - Dehydration catalysts Commercial Silica Alumma and Alumina extrudates were evaluated for dehydration ol' the Olefnic Naphtl1as. Properties ofthe extrudates are shown below in Table I.

Table I

Extrudate Silca Alulilina Alumina Method of ma1ucture 89 Y, silica alumina Altu1nna extrudate powder bound with 1 1% alumnla Particic Density 2,m/cm3 __ 0 959 1.0445 _ keletal Density, gm/cm3._. 2 837..

nor Surface area, m2/g _ ___ 16 217_ Geometric Average pore size, Angstroms 54 101 Maeropore volume, ec/g_0()0+ Angstroms) _ 0.1420 _ _ _0. 0032 Total pore volume, ee/g 0 636 0.669 _. _. . Example 3 - Dehydration over Silica Alumma The dehydration experiments were performed in one Inch downflow reactors without added gas or liquid recycle. The catalyst volume was 120 ec I'he Fe-based condensate (Feed A) was treated with the commercial silica alumina.

'I'lls catalyst was tested at 50 psig and temperature o1'480"F, 580"1;, and (8() F with space velocity at one 1,HSV and lDree LHSV. At one 1,HSV, the total olefin content was 69-70% at all three tenperatres, whcl1 indreatecl full conversion of the oxygenates At 6c,0"1<' some cracking was observed by the light product yields: total C4- was l.2% and C5-29() l-; was 25"/, (vs 20% In the feedstock). At three 1,1-lSV and 480"F and 58() F the total oleLins were lower at 53-55/o l-lrgll dehydration activity was obtained at 680"F and three 1,11SV with total olefin content of 69'/,. (JOCKS data indicated that significant amount of l-olefin was converted to lateral or branched clefts 'I'he total olefins at 480"F was (9'/, centrally brat was 55'i0 near the eild olthe test (^96() hours on stream). Signt'iearlt amount of'earbon was observed c-' n tle catalyst after inloac3n:, tl-e catalyst 'the catalyst apparently lolled.

['able 2 _ _ _. _ DellyCll action I'P72-457, S-AI catalyst

_ _

l'clll,, 14 I.l-ISV

_

Samlylc A

_

I'oduct D 68() 680 __ _ The dctai led analysis of the product (1)) from the test at 3 Ll ISC and G8() F is shown below no Table 4. 84"X, of the oxygen was removed, the eorrosror1 rating was improved, and ir on was reduced to below the level of detection. The acidity of the naplltla was reduced by 25%. The oxygenates were converted to olefins as shown by the increase rr1 olefin content and the decrease in oxygenate content.

F,xample 4 - Dehydration over Alumina I'he Co-based cold condensate (l; eedstoek B) was also treated as in Example 9, but with the ahrmna catalyst. Temperatures from 48() F to 730"1 and 1,I-ISV values From one to five were explored. At high temperature and one LMSV, GCMS data indicated that the double bond isomerizatior1 was significant (reduced alpha-olefin content). At five LllSV and 580 1F, dehydration conversion was significantly lower, and the majority of the olefins were primary linear olefins. This test ran 2000 hours with no indication ol fouling.

Table 3

Dehydration__ _ FC method Bromine method GC-MS 1'1'72-461461 Data Ma catalyst Sample ID Temp 1' 1 HSV () xygenates Brominc# "/OOleiin AlphaC4- Gas 'Rectal /,wt olefins/'l'otal Yicids A 'cl 'Ici'ils Wt"M, c No Eced 13 __ 8 6 204 24 2 940> _ () 8G 480 74213 25 2 92> () 32_ _ ShO 1 () 9275 31 8 85(yo < () 5 - 580 1 082X 2 331 t)1'3, _( 34 () 6 580 () 9-- -- 271 31 1 93(Xo () 36

-

580 2 271 313 8G(Xo < () 5 - _ 580 3 2 i265 306 8G(Xo <05 ()48 ___._ _ (3() 1 6 27 9 32.2 78(io 046 () 32

-

()() 2 () X 1 28 1 394 79')/(, () 38._ 630 3 () X 2tj.4 33 9 8G(' () 24 (if 63

_ _

630 4 () 287 33 1 87(Xo 0.2) 630. 27 3 83(Xo 018 0.7 (80 1 <().! 31 i 35.6 4() 051 0.06

_

(8() 2 0.3 267 3() 8 30' 040 0 18 680 3 05 265 30 6 7 I'3/o 033 680 3 () 6 26.9 311 7h(, < 05

-_

G8() 4 06 27.6 320 76 ) < 05 - 68() 4 () (I 291 33 3 73(Xo 020 G80 5 () 7 281 323 78(Xo 018 () 39 G80 5 0 7 27 8 319 790/0 < 05 _. _ 730 _ 31 X 361 7( _033 012 ri:hese results show that it Is possible to eliminate all the oxygenates Prom the sample and convert them to olefns. At high oxygenate removal levels, a significant portion of the alpha olefins are somen%ed to internal olefins. Although internal olefins have less value than the alpha olefins as a feedstock for ethylene production, isomerization to internal olefirls does not reduce the value below stander-d paraffinic naphtha or destroy any value for the feedstock.

Product (C) was prepared from operation at five LHSV and 680 F. Detatled propertes are shown lelow n Table 1. cS7% of the oxygen is removed, the actdity was reduce:] hy 55%, and thc trace ol ro n the sanplc was r emovecl. Tlc actUtty of tlc fnal matenal was below ().5 mg KOH/g, thc typical inaxtmum for petrolen1 crdes. Thc oxygenates were convcrtcd to olefins as shown by the ncrcase n olefin content whch approxmatcly matcle.1 the clccrease n oxygenate content.

Tablc 4 F.xpenlllent No_ __ __. 4 __ 2I _ ___3 l eecVPIocluet 11) 1 e ( ollcl I oduetCo ( ond I rocluet

A DB C

Poeess eoncltlorls Catalyst None SIAlNone Aiullnlla LllSV h- I 3 5 Jenlpelatulc 1 68() G80 I essure ps'4 5() 5() Run houl s 582-678 102G1122 A_1 56 5 __.. _.5.8 1 _ 5( 6 _ _ 57 9___ Liolmlle No 5() 6 71 7 21 27 6 Average moleeLIlal welgllt I c)3 157 183 Wt C)lcln1 51 G 7() 3 24 32 ( ea lc fi orll Br2 No) KF Watel pprll wt _ __ 4c)4 _ 58.S 0.S7 ()xygen hy NAA wt ___ 1 I _0 26 | __o 95 _ 0 12 ___ Sl C Analysls, Wttfo Siatuates 33 5 35 1 67 4 68 0

-

Arornates _ 1 2 __ _ 1 5 ___ 0 3 __ _ 0 4 Olefins 55 7 _ 62 2 23 7 30 9 Oxygenates. 1 2 8 (i () 7 Aeld Test IotalAeld mgKO11/4_ 3.17 _ __ 2_33 __ 086__ 039 13]1 Ll mgKOll/g _ 3 10.. __ 230 084 _ 035 C ll Strlp Con-oslol1 Ratng 2e 2a I b I b

-

S;ulfur ppm wt _ _ _ < | rLa < I_ < | Nltlogen pprl1 O S6 I/a _ 1 76 __ 1_29 AS l M 1)2887 SIlllulated Dlstlllatlorl by wt% 1: 0 5 8G 102 76 91 1() 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 ppm. .. .. _.

_ Fe _ _ _ 44.960 _ 0.980 2.020 _ _ <0 610 7.n 2 610 <0.380 _ <0 360 _ _ <0 350

_ _ _

Metal elements below ICP limit of detection in all samples: Al,B,Ba,(:a, (h-,CI,K,Mg,Mo,Na,Ni,P,Pb,S,S,Sn,Ti,V.

Example 5 - Adsorption of Oxygenates Trace levels of oxygenates not removed by the high temperature treatment can he removed by adsorption using sodum X.,reolite (comnlercal I 3X sieve from ESM Science, Type 13X, 8-12 Mesh Beads, Part Ntmber MX1583T-I) The adsorption test was carried out in a up-flow fixed bed unit. The feed for the adsorption studies \wras produced by process the Co condensate (Feed B) over a.lumula at 5 1,l ISV, G8()"1 and 50 psych. Tile teed for the adsorption studies had acid number of ().47 and oxygenate content by S'l'(' of () 6 g,.

Process conditions for the adsorption were an bent pressure, room teperat. re, and ().5 L1 ISV. 'l'he oxygenate content ot'tlle treated prodrets was monitored by the SFC method The adsorption experiment was continued untI hreakthi-ou,bh --- detmed as tile appearance of an oxygenate content oft) 1'/, or higher Tlie breakthrough occurred at when the sieve had dsorbed an equivalent amount of 14 wt'ho based on the Ted and proUt,ct oxygenates. The product alter treatment showed 0.()5 Wt''^, oxygen by neutron actvat'n, <0.1 ppm nitrogen, and total acid number o f 0 ()9.

'I'he adsorbent could Ire regenerated by known methods. oxidative combustion, calcnatons in mert atmosphere, water washing, and the like, and n1 combinations.

I.'hese results demonstrate that adsorption processes can also be used for oxygenate removal. They can be used as synch, or- comUmed with dehyclration.

Various modiDcatiorls and alt.eratons of this Invention will become apparent to those skilled In the art without depar-trlg I;-om the scope and spirit of this Invention. Other objects and advantages will become apparent to those shelled n1 the art Ir-om a review ofthe preccdmg

description - 24

Claims

Claims 1. A process 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 Fischer- Tropsch 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 olefins from the product stream of the naphtha cracker.
2. A process according to claim 1, wherein the olefinic naphtha has a total acid number of less than 1.5.
3. A process according to claim 1, further comprising the step of purifying the olefinic naphtha to reduce dissolved solids and acids therein to provide a purified naphtha.
4. A process according to claim 3, wherein the purified olefinic naphtha has a total acid number of less than 0.5.
5. A process according to claim 3, wherein the purifying step is performed by contacting the olefinic naphtha with a metal oxide at elevated temperatures.
6. A process according to claim 5, wherein the metal oxide is selected from the group consisting of alumina, silica, silica-alumina, zeolites, clays, and mixtures thereof.
7. A process according to claim 3, further comprising the step of separating water and carbon dioxide formed in the purifying step from the purified naphtha.
8. A process according to claim 1, wherein the olefinic naphtha comprises 10 to weight percent olefins and 20 to 90 weight percent non-olefins, wherein the non-olefins comprise greater than 50 weight percent paraffins.
9. A process according to claim 1, wherein the olefinic naphtha comprises 50 to weight percent olefins and 20 to 50 weight percent non-olefins, wherein the non-olefins comprise greater than 50 weight percent paraffins.
10. A process according to claim 1, wherein the olefinic naphtha comprises less than S weight percent aromatics, less than 5 ppm sulfur, and less than S ppm nitrogen. -
11. A process according to claim 8, wherein the olefins of the olefinic naphtha comprise greater than 50 weight % linear primary olefins.
12. A process according to claim 8 wherein the olefins of the olefinic naphtha comprise greater than 80 weight % linear primary olefns.
13. A process according to claim I, 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 a least a portion of the blended naphtha in the naphtha cracker.
14. 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 Fischer-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-olefins comprise greater than weight % paraffins; d. purifying the olefinic naphtha in the presence of a metal oxide to provide a purified olefinic naphtha having a total acid number of less than 1.5; e. converting at least a portion of the purified olefinic 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.
15. A process according to claim 14, wherein the olefins ofthe olefinic naphtha comprise greater than 50 weight % linear primary olefins, the nonolefins of the olefinic naphtha comprise greater than 90 weight % paraffins, and the paraffins have an i/n ratio of less than 1.
16. A process according to claim 14, wherein the purification step reduces the content of solids, acids, and alcohols in the olefinic naphtha.
17. A process according to claim 14, wherein the purified olefinic naphtha has a total acid number of less than 0.5. - 26
18. A process according to claim 14, wherein the purification step is performed by passing the olefinic naphtha through a purification unit containing a metal oxide under conditions of 450 to 800 F, less than 1000 psi", and 0.25 to 10 LHSV without added gaseous components.
19. A process according to claim 14, wherein the metal oxide is selected from the group consisting of alumina, silica, silica-alumina, zeolites, clays, and mixtures thereof.
20. A process for manufacturing ethylene including a first site and a second site, remote from each other, wherein the first site forms an olefinic Fischer 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 olefinic Fischer-Tropsch naphtha, which is made by a process comprising: i. converting a hydrocarbon asset to syngas; ii. subjecting the syngas to Fischer-Tropsch synthesis to form hydrocarbonaceous products; iii. isolating the olefinic Fischer-Tropsch naphtha from the hydrocarbon.ceous products; 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.
21. A process according to claim 20, wherein the olefinic naphtha has a total acid number of less than 1.5.
22. A process according to claim 20, 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.
23. A process according to claim 22, wherein the purified naphtha has a total acid number of less than 0.5.
24. A process according to claim 22, wherein the purifying is performed by contacting the olefinic naphtha with a metal oxide at elevated temperatures.
25. A process according to claim 24, wherein the metal oxide is selected from the group consisting of alumina, silica, silica-alumina, zeolites, clays, and mixtures thereof. - 27
26. A process according to claim 23, 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.
27. A process according to claim 20, 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.

lO
28. 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 l O weight %; f. a total acid number of less 1.5; and g. a boiling range of C5 to 400 F.
29. An olefinic naphtha according to claim 28, comprising at least 25 weight % olefins.
30. An olefinic naphtha according to claim 28, comprising at least 50 weight % olefins.
31. An olefinic naphtha according to claim 28, wherein the non-olefins comprise greater than 75 weight % paraffins.
32. An olefinic naphtha according to claim 28, wherein the non-olefins comprise greater than 90 weight % paraffins.
33. An olefinic naphtha according to claim 28, wherein the olefins are comprised of greater than 50 weight % linear primary olefins.
34. An olefinic naphtha according to claim 28, wherein the olefins are comprised of greater than 65 weight % linear primary olefins.
35. An olefinic naphtha according to claim 28, wherein the olefins are comprised of greater than 80 weight % linear primary olefins. - 28
36. An olefinic naphtha according to claim 28, wherein the paraffins have an i/n ratio of less than 1.
37. An olefinic naphtha according to claim 28, wherein the paraffins have an i/n ratio of less than 0.5.
38. An olefinic naphtha according to claim 28, comprising sulfur in an amount of less than 2 ppm by weight and nitrogen in an amount of less than 2 ppm by weight.
39. An olefinic naphtha according to claim 38, comprising aromatics in an amount of less than 2 weight %.
40. An olefinic naphtha according to claim 28, comprising a total acid number of less than 0.5.
41. 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.
42. A blended naphtha according to claim 41, wherein the blended naphtha has an acid number of less than 0.5.
43. A blended naphtha according to claim 41, wherein the blended naphtha comprises less than 5 ppm sulfur.
44. A blended naphtha according to claim 41, wherein the blended naphtha comprises less than 2 ppm sulfur.
45. A blended naphtha according to claim 41, wherein the blended naphtha comprises nitrogen in an amount of less than 2 ppm and aromatics in an amount of less than 2 weight %.
46. A blended naphtha according to claim 41, wherein the olefinic naphtha comprises at least 25 weight % olefins.
47. A blended naphtha according to claim 41, wherein the Gleans of the olefinic naphtha comprise greater than 65 weight % linear primary olefins. - 29
48. A blended naphtha according to claim 41, comprising 10 to 90 weight % olefinic naphtha and 90 to 10 weight % naphtha of (b).
49. A 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 50 weight % paraffins; 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.
50. 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.
51. A process according to claim 49, further comprising the step of separating water and carbon dioxide formed in the purifying step from the purified olefinic naphtha.
52. A process according to claim 49, wherein the purifying step reduces the content of solids, acids, and alcohols in the olefinic naphtha.
53. A process according to claim 49, wherein the purified naphtha isolated has a total acid number of less than 0.5.
54. A process according to claim 50, wherein the purifying step is performed by passing the olefinic 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.
55. 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; - 30 c. isolating an olefinic naphtha comprising 10 to 80 weight % olefins and to 90 weight % non-olefins, wherein the non-olefins comprise greater than 50 weight % paraffins; and 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.
56. A process according to claim 55, further comprising the step of purifying the olefinic naphtha to reduce dissolved solids and acids therein.
57. A process according to claim 56, wherein the purifying step is performed by contacting the olefinic naphtha with a metal oxide at elevated temperatures.
58. A process according to claim 57, wherein the metal oxide is selected from the group consisting of alumina, silica, silica-alumina, zeolites, clays, and mixtures thereof.
59. A process according to claim 56, wherein the purified naphtha has a total acid number of less than 0.5.
60. A process according to claim 56, wherein the purifying step is performed by passing the olefinic naphtha through a purification unit containing a metal oxide at 450 to 800 Ei, less than 1000 psi", and 0.25 to I O LHSV without added gaseous components.
61. A process according to claim 55, wherein the blended naphtha comprises 10 to 90 weight % olefinic naphtha.
62. A process according to claim 55, wherein the blended naphtha comprises less than 2 ppm sulfur.
63. 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-olefins 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 - 31 petroleum derived naphtha, a hydrotreated petroleum derived naphtha, and mixtures thereof to provide a blended naphtha, wherein the blended naphtha comprises less than] O ppm sulfur and has an acid number of less than 1.5.
64. The process according to claim 63, 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 olcfins comprise greater than 50 weight % linear primary olefins.
65. The process according to claim 63, wherein the olefinic naphtha comprises 50 to 80 weight % olefins and 20 to 50 weight % non-olefins, wherein the non olefins comprise greater than 75 weight % paraffins and the olefins comprise greater than 65 weight % linear primary olefins.
66. A process according to claim 63, wherein the blended naphtha has a total acid number of less than 0.5.
67. A process according to claim 63, wherein the blended naphtha comprises 10 to weight % olefinic naphtha.
68. A process according to claim 63, wherein the blended naphtha comprises less than ppm sulfur.
69. An product produced by the process of any one of claims 1 to 27.
70. A product according to claim 69 which is a lower olefin product.
71. A product according to claim 69 which is olefinic naphtha.
72. A product according to claim 69 which is ethylene.
73. A product according to claim 69 which is a blended naphtha.
74. A olefinic naphtha substantially as hereinbefore described, with reference to the accompanying drawing.
A blended naphtha substantially as hereinbefore described, with reference to the accompanying drawing.
76. A process for producing lower olefins substantially as hereinbefore described, with reference to the accompanying drawing.
77. A process for producing ethylene substantially as hereinbefore described, with reference to the accompanying drawing.
78. A process for producing an olefinic naphtha substantially as hereinbefore described, with reference to the accompanying drawing. - 32
79. A process for producing a blended naphtha substantially as hereinbefore described, with reference to the accompanying drawing.