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N\archtl 7 WBsgyO MspIMs IfflsffltgfiiQP Vinyl chloride monomer... What you should know This survey of the VCM (vinyl chloride monomer) industry commercial developments chemistry commercial processes and new developments indicates that VCM can remain competitive with rising crude costs R W McPherson C M Starks and G J Fryar Continental Oil Co Ponca City Okla Development of the vinyl chloride monomer (VCM) industry has been closely interrelated with the polyv nyl chloride (PVC) industry Effectively 96 percent of the VCM production goes into the manufacture of PVC Therefore technological advances in one area have significant impacts upon the other producing a domino effect This in conjunction with mcreasingh tighter en \ironmental regulations has insured a continuing evolu tion of VCM technology It is timely to review the state of the art INDUSTRY PROFILE The commercial significance of vinyl chloride monomer (VCM) can be highlighted by the statistical ranking of the 19th largest chemical commodity in the United States Turning our view upstream we real ze the significance VCM plays in wedding the petrochemical and chloro alkali industries Fig 1 schematically depicts the U S market integration surrounding VCM Pondering the posture individual companies present to the market (Table 1) one can muse as to the mot vational forces beh nd their respective business strategies It holds that if 96 percent of the VCM demand in this country is derived from PVC then VCM s future is inescapably tied to that of PVC s Within the scope of known unknowns one basic fact attests to its longevity On an energy equivalent basis PVC is one of the most energy efficient construction materials available (Table 2) This follows even after weighing the socioeconomics of health and environment Looking at the two principal components of the PVC F g 1--Shows the U S market i tegration su ounding vinyl chlor de industry Hydrocarbon Processing March 1979 OCC 014094 75 VINYL CHLORIDE MONOMER market flexible or plast cized products of wh ch fabric for automobile interiors and electrical wiring insulation are examples and rigid products including sewer and water pipes electr cal conduits and shoe soles we find the rigid aggregate growing at 9 percent per year as opposed to the flexible area hich is increasing at a rate of approximately 5 percent Within the past feiw years the rigid aggregate has surpassed the size of the flexible market which can be witnessed bv the creeping seasonal response the VCM industry has to construction the major end use outlet for rigid products TABLE 1--Nameplate capacities (MM pounds) Borden Conoco Diamond Dow Ethyl B F Goodrich 1CI Monochem PPG Shell Stauffer PVC 550 550 None None 175 1100 None None None None 420 VCM 300 700 1000 2 250 300 1 100 300 300 900 1 540 170 Ethylene None 650 None 4 800 None 350 None None None 2 700 None Chlorine None None 2 500 8 400 500 250 300 None 2 900 200 780 TABLE 2--Commercial types of VCM technology I High Purity Acetylene Feedstock II Dilute or Mixed Gas Feedstock III Balanced Ethylene Feedstock A Air Based Oxychlorination B Oxygen Based Oxychlorination Developer/Licensor Dow Ethyl ICI Solvay B F Goodrich Kureha Mitsui Toatsu Monsanto PPG Rhone Poulenc Stauffer Tokuyama Soda Toyo Soda Hoechst ICI Technology Basic Oxychlorination III A III A III AB II ___ III B III AB III B III A III AB III A III A 1-- 1-- Over the course of the pa t ten e rs VCM ha be come a tajor item of intern t onal conin e ce th the Un ted State the a ch l cl of th s b s n s B t n 1975 and 1977 eight percent of the VCM produced vas carried offshore making it third onlv to styrene monomer and toluene in the generat on of trade dollars b a che ni cal commodity This factor has tended to fill n the alleys in demand brought about by construction More sigmfi cantly it has permitted the VCM ndustrv to consistently operate near capacity le els by export ng domestic sur pluses into the world arena Looking at the global VCM market we view forces at vork chang ng the disposition of trade Beginning within the past five years Europe as a whole has s ung from a net importer to exporter of VCM With ten billion pounds of VCM capac ty integrated to vhere there is less than 15 percent mer chantly demved PVC demand producers are now chal lenging U S material for a share of the lerrnin ng odd exports Japan whose five billion pound VCM industry as built to serve the yvhole of the Asian South Pacific market first in PVC and then later in VCM has witnessed a major influx of U S and now European monomer pro ducers into their domain The present situation in the US is manifested by cheaper feedstocks v s a vis energy and an undervalued currency that together are able to offset logistical costs and remain competitive in the consuming markets E entually merging energy parity and emiss on cost pass throughs will leave U S VCM no more competitive than that of anv other nation We conclude therefore that e ports w 11 cont nue as developing th rd orld markets seek to establ sh a plast cs industry in advance of petro chemicals Conversely the major market imbalances of the past have gone by the wa s de and market growth will come from the don estic sector Fig 3 depicts the longer term outlook for VCM In making our projections e assume that the growing capital commitment req ired to make VCM will not force PVC to become uncompeti t ve y th alternati e p oducts Secondly we foresee no major technological movat on on the horizon that could radically alter the economics of production We do see ho ever technological mpro ements of degree that di rectionally level out the inflat onary trend of plant con struction Within the U S we project a 700 to 1 000 MM lb per year grass roots plant will be requ red every ty o years to meet demand It s within the scope of this t me frame that inno atioi will be tested COMMERCIAL DEVELOPMENT VCM as first produced commercially n the early 1900s via reaction of HC1 and acetylene derived from calcium carbide VCM usage in the manufacture of syn thetic rubber accelerated dramatically dur ng and after World War II This increased demand prompted searches for more econom cal hydrocarbon feedstocks Acetylene was reco ered from refin ng steps and new technology was developed to prod ce acetylene specifically from hydrocarbon cracking Ethylene became plentiful m the early 1950s Direct chlor nation processes to produce 1 2 dichloroethane (EDC) from chlorine and ethylene ere developed in /6 OCC 014095 March 1979 Hydrocarbon Processing conjunct on with EDC cracking technology to yield VCM This process yielded byproduct HC1 and did not pro 1 ferate mmed ately except m conjunction with acety lene based technology wh ch needed HC1 to produce VCM In the U S ethylene production from abundant sup plies of low cost LPG began to predominate In Europe ethylene pnces also continued to drop though not to the ame degree s nee h gher priced naphtha and gas oil were the primary feedstocks Therefore while European producers continued to use acetylene based VCM tech nology American companies moved rapidly to ethylene based technology With the startup in 1958 of the first large scale oxychlonnation process to yield EDC from HC1 and ethylene a new era in VCM technology began This balanced process allowed production of VCM from two commodity chemicals chlorine and ethylene without voluminous byproduct HC1 VINYL CHLORIDE CHEMISTRY Large scale production of vinyl chloride was first done by addition of hydrogen chloride to acetylene Fig 3--U S vinyl chloride nameplate capacity versus demand Hydrochlonnation of acetylene Catalyst HC1 + HC = CH -------------- HC = CHC1 (1) However much lower costs for production of ethylene than acetylene and the discovery that 1 2 dichloroethane (EDC) thermally decomposes to vinyl chloride in excel lent yield led to the following reaction sequence as the predominant manufacturing method for VCM Direct chlorination of ethylene CH = CH + Cl -* C1CH CH Cl EDC cracking to VCM Heat C1CH CH Cl ----------> CH = CHC1 + HC1 This method was especially advantageous for those producers having a use for the HC1 by product particu larly so if acetylene were available since then a bal anced VCM process with no coproducts could be op erated Later the discovery that oxychlonnation technology could be applied to ethylene to give 1 2 dichloroethane in high selectivity now allowed a completely balanced process based only on ethylene and chlorine as feedstocks Oxychlonnation of ethylene Catalyst CH = CH + 2HCI+1/20 -------------- < C1CH CH Cl + H O At present about 92 percent of the vinyl chloride pro duced in the United States is from plants that use the balanced process based on ethylene v a chlor nation oxychlonnation and thermal cracking of EDC These three separate steps are desenbed in greater detail below Additionally the hydrochlonnation of acetylene is also discussed below since plants using this chemistry are still n operation Moreover some recent crude oil cracking technology may narrow the cost gap between acetylene and ethylene with consequent revival of interest in VCM from acetylene Some chemistry on direct preparation of VCM from ethane is also briefly outl ned Direct chlorination of ethylene Direct chlonnation of ethylene to 1 2 dichloroethane is almost always conducted m a liquid phase reactor by intimately mixing ethylene and chlorine n liquid EDC Feme chloride a highly efficient and selective catalyst for this reaction is normally used m commercial processes Amides such as n n dimethylformamide have been reported to increase PVC selectivity Oxygen frequently present as an impunty m chlorine likewise increases EDC selectivity m direct chlorination of ethylene by inhibition of free radical re actions that give 112 trichloroethane Direct chlorination reactions may be run rich in either ethylene or chlorine depending on the methods available to the plant for handling offgases from this reactor Con version of the lean component is usually 100 percent and selectivity to EDC is greater than 99 percent 1 2 Dichloroethane as it comes from the direct chlon nation reactor is frequently of sufficient purity for crack ing except that it may contain ferric chlonde which would lead to rap d fouling of the cracking reactor To avoid expensive purification of this already pure EDC one may remove FeCl by adsorption on activated carbon or other solids Alternately one may operate the direct chlonnator at the boiling point of EDC taking pure EDC overhead and using the heat of reaction to supply the heat for vaponzat on Oxychlonnation ot ethylene to EDC Ethylene oxy chlor nat on is normally conducted at temperatures of 225 325 C and at pressures of one to 15 atmospheres Catalysts for this reaction almost always contain copper chloride and sod um or potassium chlor de deposited on alumina or other suitable support The detailed mech Hydrocarbon Processing March 1979 OCC 014096 77 VINYL CHLORIDE MONOMER an sm of the catalyst s act vity s not known but t is recognized that cupr c chlo de s the act ve chlonn t ng agent The cuprous chlonde produced is rapidly recon verted to CuCl under th eact on cond t ons but the presence of some cuprous chlor de is thought to be advantageous because it complexes with ethylene bring mg it into contact with CuCl for a long enough time for chlorination to occur The sodium or potassium chlonde serves to increase EDC selectiutj mostly by inhibiting formation of ethyl chlonde Other catalyst components such as rare earth metal chlondes sulfate salts ferric chlonde and numerous other additives have been de scnbed in the patent literature Good temperature control of the highly exothermic oxy reaction is a key element m successful production of 1 2 dichloroethane Temperatures higher than about 325 C lead to increased byproduct formation mostly through increased dehydrochlormation of EDC to vinyl chloride followed by additional oxychlonnation to give products having high levels of chlonne substitution High temperatures also increase the amount of ethylene burned to carbon monoxide and carbon dioxide Of equal lm portance high temperatures deactivate the catalyst by hjghly accelerated coking and consequent powdering of the catalyst units and by increased sublimation of copper chlonde away from the catalyst Temperature control in fluidized bed reactors is main t ined by the excellent intermixing of the catalyst par tides and by use of internal cooling surfaces Tempera ture control in fixed bed reactors is more difficult since hot spots tend to develop To keep the hot spot temperature below below 325 C yet get maximum utilization from the reactor it is common practice to pack the reactor tubes with active catalyst and inert diluent mixtures in proportions of each so adjusted as to have low catalyst activity at the inlet steadily in creasing to maximum activity at the outlet This grading of the catalyst activity flattens the temperature profile allowing for good temperature control with high produc tivity For example one patent indicates the use of four zones vith 93 percent 85 percent 40 percent and 0 percent respectively of the active catalyst pellets replaced by inert graphite As an alternate to using inert materials in the catalyst bed catalysts each with higher levels of CuCl and consequently of increasing reactivity are sometimes used Fluid bed oxychlonnation of ethylene operated under good control results in 94 97 percent ethylene conver sion 95 97 percent HC1 conversion and EDC selectivi ties in the range of 94 96 percent Fixed bed oxychlon nat ons are normally run with excess ethylene relative to HC1 result ng in 93 97 percent ethylene conversion 94 95 percent HC1 conversions and EDC selectivities of 93 95 percent These data do not include recovery of excess ethvlene in subsequent reaction steps Excess ethyl ene in vent gases from oxychlonnation is normally con verted to EDC by direct chlonnation with chlonne although if oxygen is used rather than air the excess ethylene may be recycled directly back to oxychlonnation Byproducts of ethylene oxychlonnation are vinyl chlo nde ethyl chlonde 1 1 dichloroethane vinyhdene chlo nde cis and t ans 1 2 dichloroethylenes tnchloroethyl ene chloroform carbon tetrachlonde methyl chloride methylene chloride chloral and h gh boiling compounds All of these byproducts present problems in one way or another such that the r product on need to be min m zed to lower raw material costs to lessen the difficulties of prepanng pure EDC and to prevent fouling in the cracking reactor Chloral n particular needs to be re moved since it polymerizes readily in strong acids to give solids which clog and foul operating lines and controls One must also take care to see that the feeds to oxychlonnation are pure Normally the only problem is with low levels (0 1 to 0 5 percent) of acetylene present in the HC1 from cracking of EDC Acetylene in the feed leads to the formation of considerable highly chlonnated byproducts and tars Selectne hydrogenation of this acetylene to ethylene and ethane is practiced by many companies Oxychlonnation with oxygen instead of air Use of oxygen instead of air for ethylene oxychlonnation has received much attention The outstanding benefits from using oxygen are avoidance of expensive facilities to recover EDC ethylene and other chemicals from the large nitrogen vent gas stream a large reduction in the quantity of offgases that will probably need to be in cinerated and the ability to use ethylene as a diluent for oxychlonnation a procedure said to improve heat transfer m tubular reactors Purification of EDC for cracking Great care must be taken to ensure that EDC used for cracking to vinyl chlonde is of high purity normally greater than 99 5 per cent since cracking is exceedingly susceptible to inhibition and fouling by trace amounts of impunties Additionally the EDC must be bone dry to prevent excessive corrosion downstream of the cracker For these purposes one must consider removal from EDC of byproducts from three sources EDC from direct chlorination EDC from oxy chlorination and EDC recovered from the cracking step (see below) EDC from direct chlor nation is usually quite pure greater than 99 5 percent and except for the FeCl present it needs little further purification As mentioned previously ferric chlor de may be removed by adsorption on a solid or the EDC may be distilled away from FeCl in a bo ling reactor Alternatively the feme chlo ride may be removed by washing ith water usually in conjunction with oxy EDC 1 2 Dichloroethane from oxychlonnation contains a variety of impurities as 1 sted previously EDC from this source is usually washed \ ith water and then with caustic solution to remove chloral and other water extractable mpunties Low boiling impurities and water are taken overhead in a first (light ends) distillation column and then pure dry EDC is taken overhead in a second (heavy ends) column EDC recovered from the cracking step contains an 78 OCC 014097 March 1979 Hydrocarbon Processing apprec able number of impurities of hich t o chloro- prene and trichloroethylene are not readilj remotable b) distillation necessitating the use of other treatments Chloroprene if not altered bv chemical treatment con centrates in the light ends column where it can polymerize to solid or rubbery materials which senously foul and upset this column Trichloroethylene forms an azeotrope with EDC boiling very close to EDC If it is not removed n some way t accumulates n the EDC leading to re duced cracking rates and increased fouling Both impun ties may be removed by subjecting the recycle EDC stream to chlorination pr or to distillation Treatments with HC1 and by hydrogenation have also been patented as methods for removal of chloroprene Cracking of 1 2 dichloroethane to vinyl chloride At temperatures m the range of 425 550 C and near at mosphenc pressure EDC undergoes clean thermal dehy drochlormation (cracking) to yield vinyl chloride and hydrogen doride Heat C1CH CH Cl ---------- CH = CHC1 + HC1 The mechanism of this reaction has been extensively investigated and shown to irvolve a sequence of free radical intermediates Use of pressure up to 25 to 30 atmospheres during cracking at temperatures of 500 550 C provides better heat transfer reduced equipment size and easier separa tion of HC1 from the product by fractional distillation EDC conversion levels are normally maintained m the range of 50 to 60 percent at residence times of 2 to 30 seconds with selectivities of VCM ranging from 96 to 99 percent Some byproducts generated dunng crack ing act as inhibitors to the free radical sequence so that increasing se enty leads to smaller and smaller increases in EDC con ersion ith correspondingly increasing levels of byproducts Var ous mater als such as chlorine bro mine or oxygen have been shown to be initiators for EDC cracking 8 Recently however exclusion of oxygen s claimed to result in cons derable reduction of fouling on the cracker tube walls A rather spectacular claim has been made that use of nitromethane as an initiator provides EDC convers on levels of up to 92 5 percent at 480 C An important processing requirement m EDC cracking is rapid cooling or quenching of the re action mixture If cool ng is done too slowly substantial yield losses to heavy ends and tars result Byproducts from the cracking reaction include acetyl ene ethylene methyl chloride butadiene vinyl acetylene benzene chloroprene vinylidene chloride 1 1 dichloro ethane chloroform carbon tetrachloride 1 1 1 trichloro ethane and other compounds Most of these impurities remain in the unconverted EDC fraction and are re moved when this stream is distilled Ethylene and acety lene codist 11 with the HC1 and are thus routed back to oxychlonnation (after optional hydrogenation of the acetjlene to ethylene) Methyl chloride and butadiene more or less codistill with the vinyl chloride depending on the efficiency of the VCM fractional distillation sys tern Add t on of chlorine or carbon tetrachloride to the cracker feed is claimed to suppress methyl chloride for mation Removal of butadiene a contaminant which can interfere with poljmerization of VCM has been done by treatment with chlorine anhydrous HC1 or selective hydrogenation HCI addition to acetylene Recent development of a new crude oil cracking process using very high tern perature steam (2 000C) as a heat transfer fluid pro duces substant al yield of acetylene along with ethyle 1 Under some economic and geographic conditions the use of this cracking process may be advantageous and may thereby provide acetylene for vinyl chloride pro duction Typical conditions of hydrogen chloride addition to acetylene are total pressures on the order of five to 15 atmospheres temperatures of 150 to 180 C and use of a mercuric chlonde on carbon catalyst 8 With stoichio metric quantities of reactants essentially 100 percent con version is observed with VCM selectivities on the order of 98 percent It is notable that ethylene does not react under these conditions thereby allowing the use of mixed ethylene acetylene streams as feeds Ethylene easily re covered from the vinyl chlonde product by fractional distillation is then chlonnated to yield 1 2 dichloroethane Other catalysts have been shown to be effective for addition of HCI to acetylene but HgCl is vastly supe nor However in addition to the general toxicity prob lems involved m working with mercury containing substances HgCl has appreciable volatility under the above reaction conditions leading to a need for consider able care and control in operation of the reactor In fixed bed operations HgCl vaponzes from the hot spot of the reactors condenses at cooler locations downstream and results n continuous movement of the hot spot downstream with eventual loss of catalytic activity This loss is minimized by periodic reversal of flow through the reactor Ethane based vinyl chloride processes A number of patents dealing with chemistry for conversion of ethane to EDC and/or VCM have been publ shed in recent years Most of these reactions involve high tempera ture oxychlonnat ons such as CuCl Catalyst CH CH + HCI + O 350 450 C CH = CHC1 + 2H O However these processes suffer from a number of dis advantages the most important of which includes lot selectivities low conversions and difficult operating con dit ons such as CuCl sublimation One reaction system based on ethane called the TRANSCAT process has been developed on a large pilot plant scale but is not yet m commercial practice The chemistry of th s process s a complex senes of re actions generally involving chlonnation dehydrochlon nat on and o ychlor nation A mixture of ethane eth ylene ethyl chloride chlorine and HCI are fed to a melt of cupric oxychloride and jxitassium chlonde yielding vinyl chloride water and cuprous chloride as the mam products The cuprous chlonde potassium chloride prod uct is taken to an oxidation reactor where the cupnc oxychlonde is regenerated by treatment with air Vinyl chlor de is separated from the organic product and pun Hydrocarbon Processing March 1979 OCC 014098 79 VINYL CHLORIDE MONOMER TABLE 3--Current VCM technology sources fied by fractional distillation Removal of about 0 4 per cent butane plu buten s p es nt in tb main VCM cut represents a very difficult separation Ethyl chloride and ethylene can be recycled into the feed Chlonne valu s in the thlor nated byproducts can be recovered by incineration and then feeding these gases to the cuprous chloride oxidative regenerator reactor Disposal of byproducts Disposal of byproducts pre sents special problems for vinvl chloride manufacturing plants since a variety of gaseous organic liquid and acqueous streams must be handled each with its own particular problems Vent gas streams from various units may contain small amounts of HC1 chlorine ethylene vinyl chloride methane and carbon monoxide These streams may some times be treated by scrubbing chemical treatment sorption or other methods to recover some chemicals when economically justified Otherwise the common cleanup technique is either incineration or catalytic com bustion followed by recovery of HC1 from the vent gases Two organic byproduct streams are produced The light ends contain mainly ethyl chloride as and trans 1 2 dichloroethylene chloroform and carbon tetrachloride The heavy ends or tars contain mostly 1 1 2 tnchloro ethane lesser concentrations of tetrachloroethanes chlon nated butanes chlorinated aromatics and a large number of other compounds present m small amounts These streams are normally fractionated to recover useful com ponents the others incinerated to recover chlonne values either as aqueous or anhydrous HC1 Process water streams are steam stopped to remove volatile organics followed by neutralization and then treatment in an activated sludge system to remove non volatile organics in the water COMMERCIAL PROCESSES Broadly speaking there are three types of VCM pro cesses n commercial use today These are categorized as acetylene ethylene or mixed gas based on feedstock re quirement Within the ethylene type plants further classification is desirable to d stinguish the type of oxy chlorination technology used l e oxygen versus air feed stock (see Table 2) Over 90 percent of the world s listed 35 billion lb per year VCM capacity currently is based upon the balanced ethylene feedstock route Of this just under 90 percent uses air based oxychlorination How ever of the projected worldwide plant startups for the period 1979 1981 approximately 30 percent of the 7 7 billion lbs per year VCM will be derived from oxygen based oxychlorination Other existing producers will un doubtedly be evaluating the conversion of present air based plants to the use of oxygen during this time frame Table 3 presents a summary of the technology sources in use today It is thought that the technology currently licensed by ICI and Solvay is similar to the process normally attributed to Ethyl The efore all are listed under Ethyl s technology It is interesting to note that several plants ex st where the oxychlorination process Technology S urce 1 B F Goodrich 2 Hoechst/BFG 3 Stauffer/BFG 4 Stauffer 5 Ethyl Solvay ICI 6 Dow 7 PPG 8 Rhone Poulene 9 Monsanto 10 Toyo Soda 11 Tokuyama Soda 12 Mitsui Toatsu 13 Kuteha 14 Miscellaneous Existing VCM Plants MM Lbs /Yr 18 5840 11 4 290 5 2360 19 6390 14 5 000 7 3 040 5 1700 5 1330 4 1110 3 400 2 660 3 610 2 410 10 2 400 107 35 540 Planned (1979 1981) Plant VCM MM Lbs /Yr 4 2160 2 580 ---- 2 350 1 260 3 1050 3 1780 1 500 I 250 1 330 ---- 1 90 ---- 1 330 20 7 680 Oxychlorination process provided by BFG of one licensor B F Goodrich has been combined with direct chlorination and VCM technologies of others l e Hoechst and Stauffer Table 4 presents a tabulation of worldwide VCM producers This summary was prepared from scores of literature sources some of which were contradictory However the authors have exercised their best judgment m the absence of specific information from the listed licensors The reader is referred to Leonard Gomi or Sittig5 for details of the acetylene and mixed gas routes to VCM The technology discussion herein will be limited to the balanced ethylene feedstock route used overwhelmingly today Although each of the major technology licensors has many patents none has complete coverage of each step of his process As a result the sequence and type of operating steps tend to be very similar from process to process The basic differences stem from the oxychlorina tion technology and the types of impurities appearing in the crude EDC The licensor therefore provides process know how primarily as opposed to patent position As a result published literature by major licensors is under standably very sparse and highly simplified with certain exceptions TYPICAL VCM PROCESS The typical VCM process combines direct and oxy chlorination (oxy) processes to provide 1 2 dichloro ethane (EDC) feedstock for the EDC pyrolysis unit (see Fig 4) The direct chlorination process relative to oxy is char acterized by low capital investment low operating costs and high purity product However HC1 generated from the EDC pyrolysis unit dictates the use of an oxy unit With the current pyrolysis yield of approximately 0 55 mol VCM per mol EDC fed and the HC1 yield of 1 mol per mol VCM the oxy unit size is set at approximately 0 5 mol EDC per mol of VCM desired This sets the direct chlorination unit size at approximately 0 5 mol EDC per mol VCM The combined EDC streams are caustic treated to re 80 OCC 014099 March 1979 Hydrocarbon Processing n> ? Fig 5--Schematic of the Stauffer v nyl chloride monomer process Hydrocarbon Processing March 1979 OCC 014100 81 TABLE 4--VCM plants--worldwide--(cont d) Op t Italy A Rm Sd SARP St St S G son i d t JP Asah P Chb VCM D k Kgk J p Gc K gf h K g f ft K h m VCM Kh M t b h M sa t Ml T t Ry N h C Ltd S yM m Sh P t h m 1 S ml m S A Ch in 1 T y G se Ty Sd K KP KP L by GNOI f f Pm M oc SNEP N wy N k Hyd Soc d d P mg LTOA P1 d P 1m C k p P tg1 CNP Rm i 1 d t i imp St 1 A th ty S th Af ica Af ca l p| d Ch sp Mt 1 R Rd Sw d Km b 1 S itz 1 d L 132 Tw F m sa PI t Ch g T (?) T k P tk m U it d K gd m B t hPt 1 m (Cl USSR T hm h mp I v p t pi' V* 1 Ok Km 1 d H m j k Id D /l L cat R na d P rt M gh c gl C gl T m Itn Pl Rym P rt T Chb Chb M mt Chb Tk k T k sag T k sag K hm N hk Ykk h N gy Osak Ch b M hm M hm Tok y m Nhm Tkym T k hm Tkym C ty Y kk h Yeo-S Ulsa Ab K mm h pi i P ja t M h mm d R1 P mg Wlocl k S R m Vice R m VI f S solb g \ S solb Tl l8 l1 TH 1 8 M t II H1 St g d L Id Kh g Tf Y m (ml Al g 1 m B gl B y W 1 H lift se R Dj ) k Gk Gk K1 h V Ig g d Zm FIT M Sk pi P KRK P oc A/ / M/A/O M/A/O //D E/A/O AE/ /D E/A/B W /D E/A/B E/A/B E/A/B M/ /D AE/A/ AE/A/O E/A/B AE/A/O E/A/B AE/A/O A/ / E/A/B UNO M//0 E/A/B e/a/b E/A/B e/a/b E/A/O E/O/B PI d E/o/B E/ /D A/ / E/A/B E/A/B A// E/A/B E/O/B/ E/ /D AE/A/O A/ / E/A/B e/a/b/ EA/ /D E/A/B E/A/B E/A/B Sta t p Y 1971 1969 1970 1965 1976 1967 1971 1967 1969 1970 1970 1964 1970 1964 WO 1968 1970 1970 1968 1967 1966 (1979) (1980) 1978 1976 1978 (1979) (1981) 1968 1978 (1980) 1970 (1981) 1967 L St A BFG BFG PPG PPG Ethyl i'y PPG su n T y Sod D k Kgk J p se Geo St ufl St uff BFG Kh M sa t Mt T t M Is T tsv T y Sod BFG BFG Tkym S d St ft Tkym Sod T y G se T y Sod Ty Sd D D BFG Hoe h t M sa t BFG Sta fl BFG Hoe h t V Ica PPG D Mts T t ICI S 1 y T M sa t M sa t M sa t M S3 to Rh ne-P g 1 S1 y D Sta fl 1973 (1981) 1971 1970 1974 (1979) 1977 (1979) (1981) St fl Mt T t S1 y ICI S 1 y BFG Sl y S1 y Rh P gl Sta ff Rh P gl BFG H h t Kh BFG H h t BFG Rh P gl St fl D CE *t t / F t Wh 1 Opt S 1 E t co S1 y E t co S mt m Ht h K gf h Ch yod Ty Eg Ty 1 Ht h g g Ht h Fl /Dim P oco F Uhd S 1 g U L mm Bft Kb B dg P t ocarb D y P g Klock 7r g g H mph & Gi g C wf d R 1 L mm M Kee CTIP M K CTIP M K CTIP Lg H mph y d Gl g CTIP CFB CFB Sp hm Sp hm Sp h m F Uhd Chy d F Uhd F t Wh 1 llmttbltdfmmy I P th d t th tpl t th ghtt b { g Led Hyd b F (E)thyl (A) tyl (M) d G t k / 0 yfi (A) (0) yg P oc (B) I (0) y 10) d !)f tdt g d/ t th h d th b t j dgm t dh t h d p t | tt VCM c ty MM Lb /Y ------------------------- 165 400 350 (110) 290 no 310 350 220 (330) 257 331 770 130 130 73 238 440 180 220 88 110 220 (330) 132 (136) 155 440 59 660 17 (450) (330) 88 350 60 440 176 330 (250) 530 220 (500) 265 (770) ISO 44 530 (530) 119 (257) 573 66 73 68 550 145 (595) no no (220) (440) 82 March 1979 Hydrocarbon Processing OCC 014101 VINYL CHLORIDE MONOMER TABLE 4--VCM plants--worldwide Op t U t d St t ICt Am C oc Ch m Dw ! Ethyl C p B F G od h M hm PPG Sh II Ch m 1 St ff B d Ch m G gPf Dm d Sh m Ale 1 S th k 0 Qm El t ocl A t1 1 nz B Igi m BASF lb h m l mb g (LVM) B1 Cpm Mm Pt q B Ig Tb Cd D V1 Cm mpl kt Sh g Chil Pt q m D /ENAP Chi T h limp tC p C 1 mb P t q m C 1 mb C hi k Ch m p t 1 Ch m k Fl d dy W P P k m Oy k AKZO Ch m EMC/DSM Df S1 PCUK/5h il Ch m E tG m y 1 d t A 1 g Imp t W tG m y Al H1 BASF S1 y Dy m t N b 1 H ht K p k AG Wk ICI Ethyl H II K II d AKZO H ht Sh 1) H ty Ch m k mpl B d V gy K mb t 1 CSP 1 d N t 1 0 g Ch m 1 Ab d P t h m i 1 Jp JV St t El t h m lid t L cat Bt R g l l k Ch 1 l F p tT Oy t C k T PI q m ne l 8t R j L H tT Cl tCty K t ky GmL L k Ch 1 L L k Ch 1 L Gy II P ft R D P kT Nl L (B h C If Gm L PI q m L Dm P k T Sk kd B h Bl nc C pt B m d B h Bl B f ry A lT 1 d 1 J ppe S El 1 Bh Bl nc Cm Bg D y S 0t F tS k t h V Qb Sh w g Q b C pc C pc Pk g Nt N ky SI k P G I II iH Ottm h m J l St A b St F T FS M S hk p Wlh Im h M1 L dw g h Rh b g l 1 d rf G df K psa k VI g K psa k K psa k B gh B gh se Wlh 1m h Th ssal k B (I k B If k (E p VI g P ) Bt Bl K bk Md B mb y Ab d Bd B Hf Akk P E/A/B E/A/B E/A/O E/A/O A// e/o/b e/o/b E/O/B E/A/B/ e/a/b E/A/B E/A/B e/o/b E/A/B E/o/b E/A/B A/ /D E/A/B E/A/B e/a/b E/A/B E/A/B E/O/B E/A/B A/A/O E/A/O E/A/B E/A/B M/ /D Sta t p y 1968 1968 1969 1978 1964 1960 (1980) 1971 1972 1972 1957 (1980) 1978 (1979) 1967 1972 1976 1968 1972 (1979) (1979) (1979) 1967 1969 1978 1973 1972 1972 1971 Li BFG st n D D Dow Ethyl Ethyl BFG PPG PPG PPG St St ft SU ff Sta ff PPG St ff BFG Mt T ts D ICI BFG ICI Stauff BFG Hoech t BFG H h t BFG Ethyl SI y ICI BFG BFG PPG D D BFG BFG Dw B F Good h St fl St ft BFG Hoe h t S1 y E |l / C tr to. R M P so F d B &D RMP so Fl RMP so RMP so CFB RMP so B w d Root L mm B die 8 Ty E| , Ch m co B dg BASF B dg B dg S1 y M K CTIP B dg B dg /P m 7 h p/TPL B dg F h E g ee g F t/Ad VCM MM Lb ft ---------- ------------- - 300 700 200 700 1150 300 150 1050 300 (1 000) 700 11 1 (1 000) 1000 (88) 73 287 7 (1 100) 440 550 220 (286) (330) (330) 7 (660) 126 126 35 35 176 F Uhd CTfP 265 240 88 E/A/B M/ /D e/a/b E/A/B E/A/B AE/ /D At/ /D E/A/B E/A/O E/A/O ea/a/o E/A/O E/A/B E/ /D E/A/B E/A/B E/A/B E/ /D A// e/a/b E/A/B e/a/b 1967 1970 1965 (1980) (1979) 1973 1966 1972 1963 1971 (1980) 1971 (1979) (1981) 1978 1967 1969 (1979) (1980) (1979) St fl BFG Hoe h t Rh P gl Rh P gl BFG Hoe h t S 1 y thyl BFG H ht Rh P gl Rh P gl S1 y B dg F Uhd H1 St ufi sSt 1 fJf BFG BFG Hoe h t BFG H h t BFG BFG St ff /St ff Wk (Cl Ethyl SI ff /BFG H ht S1 y CFB Uhd B dg Uhd B dg Uhd B dg K psa k RMP R M P so Fl C mp mo-l g AKZO L t t H ht BFG Hoe h t BFG H h t BFG Sh ff BASF BFG T y Sod St fl Mt Uhd B dg B dg B dg L m Ht h L mm Thy se 440 795 291 440 440 (440) (440) (660) 700-770 160-320 440 130 375 220 (MO) 220 330 176 350 (680) 33 660 (330) (350) 79 350 350 33 45 130 (330) 145 29 (220) Hydrocarbon Processing March 1979 OCC 014102 83 VINYL CHLORIDE MONOMER move HC1 and certain clorinated byproducts which otherwise would hinder fractionation or pyrolysis The clean EDC is subjected to distillation steps in which water and other light components are removed as well as heavy components typically labeled tars The dry product EDC generally of 99 5 percent or greater purity is thermally cracked to yield HC1 and VCM m an EDC carrier stream Further distillation equipment separates EDC and HC1 for recycle and yields product VCM for final treating The typical VCM plant includes VCM treating offgas treating light ends/tars handling and waste treating facili ties It will also include incineration units for reclaiming waste chlorinated hydrocarbons from offgas or liquid streams heat is removed by generation of steam on the shell side of each reactor The final reactor effluent is cooled to condense EDC and the offgas is contacted/reacted with chlorine to recover ethylene as additional EDC The offgas stream is cooled versus cooling water and refrig eration to further condense EDC before exiting the pro cess Residual ethylene concentration in the vent gas is reportedly as low as 10 ppm Stauffer also offers an oxygen based oxy process (Fig 6) m which the mam reactor offgas following condensa tion of EDC is compressed and recycled to the first oxy reactor An excess of ethylene is used to maximize HC1 convers on and minimize byproducts A small slipstream from the ethylene rich recycle is purged to an ethylene recovery unit for control of inerts Stauffer technology In the Stauffer direct chlori nation process (see Fig 5) ethylene and chlorine are reacted in the hqu d phase and under controlled condi tions to yield a crude product which analyzes 99 7 per cent EDC The reactor product is then combined with the crude oxy EDC washed and distilled to remove water light ends and heavy ends Pure EDC is preheated in the economizer of the pyrolysis furnace and then vaporized with steam EDC vapor is then heated to dissociait on temperature in the furnace tubes to yield a mixture of vinyl chloride and hydrogen chloride Conditions are controlled to maintain EDC conversion at 50 to 55 percent Following a quench and condensation step HC1 VCM and uncracked EDC are separated by distillation Hydrogen chloride gas is sent to the oxy section Unreacted EDC is recycled to purification The oxy section combines recycle HC1 with fresh ethyl ene and air in tubular fixed bed catalytic reactors The ethylene and air are fed m excess of stoichiometric re quirements to assure high HC1 conversion Reaction Ethyl integrated VCM process Gaseous chlorine and ethylene are introduced into a direct chlorination reactor in which they combine to form EDC The very high purity EDC product can be sent directly to (or after degassing can bypass) the EDC purification system -(see Fig 7) Air and gaseous ethylene and HC1 are introduced into an oxychlonnation reactor in which EDC is produced at an elevated pressure and temperature in the presence of a fluidized catalyst The reaction products are neutralized ard part ally condensed to recover EDC which is first sent to a drying column and then to the EDC purification system A portion of the vent gas consisting primarily of n t ogen and carbon d oxide is recycled to the reactor for added safety The purified EDC stream which contains recycled EDC as well as the EDC from direct and oxychlonna tion is vaporized and introduced into a furnace At least half of the EDC stream is cracked to HC1 and VCM The reaction products are cooled rapidly partially con densed and then sent to the VCM purification system 84 OCC 014103 March 1979 Hydrocarbon Processing Fig 7--Ethyl Corp s integrated vinyl chloride monomer process HC1 and VCM are separated by fractional distillation from the unconverted EDC and small amounts of by products The EDC containing the byproducts is re cycled to the EDC purification system Mitsui Toatsu Chemicals technology The MTC technology utilizes a boiling liquid process for the direct chlorination reaction Reaction heat is dissipated with the gaseous EDC exit stream which is condensed externally and sent to purification The oxychlonnation process is characterized by the use of oxygen feedstock and a fluidized bed reactor The reactor effluent gases are quench cooled with circulating EDC followed by caustic neutralization The neutralized gas is cooled to condense EDC and ater Uncondensed gases primarily ethylene are recycled back to the oxy reactor A small stream is vented from the recycle gas to allow purging of inerts EDC liquid is phase separated from water and dehydrated before joining the EDC streams in the purification system A conventional EDC purification system splits crude EDC into light ends heavy residue and pure EDC The latter is cracked to yield VCM which is purified in a manner similar to that described in the Stauffer tech nology (see Fig 8) PPG technology The EDC production technology appears very similar to that described for Mitsui Toatsu particularly in the use of oxygen feedstock and fluidi ed bed reaction for oxychlonnation However PPG does not indicate use of a dehydrator to dry crude oxy EDC prior to purification Also PPG uses three rather than two towers to obtain the HC1 VCM EDC separation B F Goodrich technology Goodnch direct chlon nation uses conventional water cooled technology similar to that shown for Stauffer The air based fluidized bed oxychlonnation technology is similar to that shown for Ethyl Goodrich also utilizes an absorber stnpper system on the oxy \ent gas stream to minimize hydrocarbon losses Goodnch in conjunction with Badger Inc offers complete technology for waste treating of VCM plant effluent streams Toyo Soda technology This technology appears very similar to that offered by Stauffer The principal differences are m the use of an absorber stnpper on the oxy vent gas effluent (as with Goodnch) and the de hydration of crude EDC prior to punfication As with other oxychlonnation processes steam generation is used to remove reaction heat Phone Poulenc technology Rhone Poulenc offers two processes Chloe I and Chloe II The former is of a special nature to yield concurrently significant quantities of other chlorinated hydrocarbons such as tnchloroethyl ene and tnchloroethane The Chloe II process is true VCM technology using air based fluid zed bed oxychlo rination m combination with boiling liquid direct chlo nnation Monsanto technology This process appears very s mi lar to that offered by Stauffer Hydrocarbon Processing March 1979 OCC 014104 85 VINYL CHLORIDE MONOMER A- l` WI*: 1 lit ' L-'C'O ` it..,. S2S hfm sa^jp-i ,lw^/qg^y 9-ir r#~ ">>33 Caustic 001 m ^"d^HSIka uC- S -,0We EDC pyrotyia VCM purification 4sd i ifrfi %* *** ". -* 1<6 i * w* s: Fig 8--Mitsui Toatsu uses these modifications in their vinyl chloride monomer process DOW technology Dows technology has not been pub hcized It has been used only by Dow and its foreign affiliates NEW DEVELOPMENTS Although it is believed that several VCM producers currently use boiling liquid reactors for direct chlonna tion Stauffer has developed a unique application of this concept Their approach High Temperature Chlonna tion in effect uses the reactor as a reboiler for the con ventional EDC purification system (see Fig 9) Punfied EDC is withdrawn as a side stream from the tower and any light components formed are removed overhead Normal feed to the tower consists of treated EDC from oxy and recycle Small amounts of the normal heavy ends or tars are purged from the base of the reactor This ap plication eliminates approximately 100 000 lbs per hour of 150 psig steam consumption for a one billion lb per year VCM plant A similar energy savings is achieved in reduction of cooling water usage relative to a conven t onal reactor and 1 ght ends tower B F Goodrich also offers a boiling liquid process m which the heat of reaction is utilized to purify all EDC processed in the purification tram Increased activity by EPA (US Environmental Pro tection Agency) and state agencies in regulating hydro D t chlo ti eaclo a d he vy ds col mn ' d F g 9--Stauffer high temperature chlor nation and ethylene dichloride purif cation schematic 86 OCC 014105 March 1979 Hydrocarbon Processing carbon emissions are likely to stimulate further new de velopments particularly in oxychlonnation processes These will range from development of new oxygen based t chnology to va ous add on y t ms fo clean ng up oxy vent gas The latter may include catalytic oxidation m cineration (of oxygen based oxy vent gas) solvent absorp t on combined refngerat on and absorption techn ques and/or other combinations Several companies not active as VCM producers are involved m developing these add on systems It is expected that companies will continue to devote considerable effort to the development of cracking pro moters and inhibitors of side reactions m pyrolysis chem istry Current cracking practices limit EDC conversion to 50 60 percent Considerable energy and cost savings could be achieved through increased conversion levels without concurrent losses of EDC to undesirable side reactions The net effect of these various regulations has been to increase substantially the scope of add on technology in VCM plants such as Installation of pnmary and redundant nc ne at on facilities for VCM point (ex oxy) source and collected fugit v emissions Installation of HC1 scrubbing and neutralization or recovery units in conjunction with the incinerators Installation of closed process sewers collection sys terns and larger or redundant waste water stnppers Replacement of single mechanical seals on pumps and agitators with double mechanical seals (In some cases conventional pumps were replaced with canned or magnetic drive pumps) Leak detection systems and portable monitors EPA regulations EPA s Standard Support and Envi ronmental Impact Statement Emission Standard for Vinyl Chloride presented the following regulations Emiss ons from all point sources except oxychlonna tion would be reduced to 10 ppm VCM by volume Emissions from the oxychlonnation reactor would be reduced to 0 02 lb VCM per 100 lbs EDC product from the oxy process Preventable relief valve discharges would not be permitted Fugitive emissions would be minimized by requiring enclosure of the emission sources and collection of the emissions EPA estimated typical VCM plant emissions m 1974 as follows Lbs /VCM/ Source 100 Lbs VCM Fugitive 0 1215 EDC Finishing Column 0 05 VCM Finishing Column 0 24 Oxy Process 0 0364 Process Water 0 0007 Total 0 4479 The regulations were predicated upon reduction of such emissions by 94 percent using best available technology Compliance testing of these installations was begun in the last quarter of 1978 Additional EPA and state actions were initiated in mid 1977 to reduce hydrocarbon emissions from VCM plants in non attainment regions i e much of the Gulf Coast EDC production is reported to account for 28 percent of the hydrocarbon emissions in the southern Lou siana and East Texas AQCRs These actions were directed primarily against oxychlonnation vent gas from air based units The amount of hydrocarbon reduction sought aries from region to region No published g ide lines are currently available to reference Enclosed sampling and analytical systems Vapor recovery systems for VCM loading/unloading and equipment clearing The EPA report estimated a maximum capital impact of $0 8 to $19 MM (1975 dollars) for a model 700 MM lb per year VCM plant Recent cost estimates in dicate the true impact for these items is nearer $15 MM based on 1978 dollars Addition of hydrocarbon compli ance (proposed regulations) may add another $2 $5 MM EPA also has proposed further reductions in VCM emissions Under consideration at present are regulations which will reduce allowable emissions from 10 ppm to 5 ppm for all point sources including oxy vent gas EPA further plans to prohibit emission increases within 8 kilometers of an existing source due to construction of a new em ssion source This will effectively prevent expan sion of existing facilities or construction of new plants in the vicinity of existing plants The proposed oxy vent gas regulation will also dictate substantial capital expendi tures for add on facilities and possibly the conversion of air based to oxygen based plants to facilitate incineration of tail gases ECONOMICS Table 5 presents a 1981 manufacturing cost buildup for a typical 700 MM lb per year grass roots VCM plant Raw materials total 12 cents per lb VCM or 54 pe cent of the required FOB plant selling price Capital related costs amount to 6 8 cents per lb VCM or 32 percent Utilities are only 6 7 percent of the total VCM cost In perspective the 1972 1973 reported VCM selling price was only 4 5 cents per lb By 1981 the capital related unit costs alone will exceed this by 50 percent The obvious major factor in VCM pricing is raw ma tenals cost Although chlorine price is expected to double between 1973 and 1981 the impact of ethylene pnce will be even greater (three cents per lb versus 17 cents per lb ) The real culprit of course is crude oil cost During the late 1960s and early 1970s plants using inexpensive LNG feedstocks were s gnificant contributors to the low cost U S ethylene supply picture The energy crisis rap dly reversed the low cost feedstock trend LNG scarcity Hydrocarbon Processing March 1979 OCC 014106 87 VINYL CHLORIDE MONOMER dictated construction of naphtha and/or gas oil crackers for present and future ethylene production This tied VCM prices irreversibly to crude oil prices through ethylene fuel and power (particularly via its impact on chlor ne) ACKNOWLEDGMENTS Th thor g f lly k owl dg txib b A B 5 rykcr J f Sta ft d H H Wall f Etn 1 and penmssi by th mp lues us th frm pot d h cape p oceucs LITERATURE CITED U.S E nm tal P Ag cy R p R rch T glPkNC (1975) N EPA-450/2 75-009 L ch H S ( M man Ch mical Co ) U S Pa 3 338 982 (1967) B F G odr h C British P 1 233 238 (1971) Campb 11 R G ( S ff Ch mical C ) US P 4 000 205 (1976) B d D(tU C b d ) US P t 2 929 852 (1960) DF L d C Icag B ( 3 911 036 (1975) T U (t L mm C ) US P Soc Ital R ) U S P 3 917 727 (1975) K tz B D d Om lta A ( All dCbmcalC) US P 3 941 568 (1976) VlanMa Is B hP 980 983 (1965) V A w rp A E H prt g J W S btu R G (to B F Goodrich) U S P 3 488 398 (1970) dK g T L Sc F T ( Sta ffer Ch meal C ) US P 4 046 822 <1(97 ) S ufl Ch mical C B tills Pi t 1 230 607 (1971) B F Good ch Co B lg m P 680 413 (1966) K H(M T Ch m 1) J P P 46-43367 (1971) " Miya chi K ( M tail Toad Ch m cal) Bn h P (1970) 1 189 815 M Tak hash T ( M ts T Ch m cal) J p (1970) M T ts Ch mical J p P t 46-33010 (1971) PPG Id F ch P 2 080 666 (1971) P 45 32406 M AP ( "AhlosnJ (1976) S nn J C (1976) PPG I dus ncs) B hP 1 220 394 (1971) RC( D w Ch mical C ) U SP 3 966 3 d C J R ( Rh P og 1) U S P 3 935 286 About the authors Robert W McPherson is pr duct manager Continental Oil Co Houston He is respons ble for th ido Idwide profit performance f C no s chi rmated hyd a bons and th r st ateg c development Mr McPherson rece ited his BJS from Cornell University Charles M Starks is d ect f ex plorat ry esearch Continental Oil Co Ponca City Okla Dr Starks received h BS fr m the Un v sity of Okla h ma and his PhD f m Massachus tts Institute f Te hn logy Garvin J Fryar is sup rinsing pr c ss eng n er with C nt nental Oil Co Ponca City Okla He is r sponsible for the superv si on of p ocess designs te hn al nsult ng and econ m cs for hem cals p o e s s M Fryar ited his BJS n h m cal eng n nng f om the Unive s ty of New M it o TABLE 5--Estimated 1981 VCM manufacturing cost R M te 1 Chi Ethyl ne C taty t d h meal Util t> T tal bi Lab M sc 11 ne T Ulfi ed T btm ft g Cptathg ddp S II g p ce FOB pi nt t t Lb /Lb VCM m t 084 58 0 49 171 or 3 53 8 45 0 39 142 13 79 1 18 0 98 2 16 15 95 5 85 2179 % 16 2 38 8 18 65 63 3 54 45 99 73 2 26 8 100 0 B KM 1 700 MM P d /Y B I d VCM PI t 2 1981 Start p 3 G ss Root I tm I 3140 MM 4 Ight nd h y d nc t d ov d HC1 sold m ti d t b nc ti t 5 F ft p t DCF t f t t t t h s d p ft 6Utl g Id d t pe fk t prtllseso t h k I gy Small y W , Kurtz B d Bandy p dby y B ( All d Cl m cal C rp ) US P 4 060 460 (1977) K psack C B tub P 1 266 676 (1972) Sl y ta F hP 1 602 522 (1971) k kl A ( Knap kC ) US P 1 3 484 493 (1969) * J kirn A G ( 1CI) B tuh P 956,618 (1964) Foelch W ( H ech ) G m P 2 217 694 (1973) B t D H R J Ch m Soc148 (1949) Y g D P ( BP Chem 1 Ld) US P 3 896 182 (1975) * M t Ch mical 1 d J p P 42 22921 (1967) B F G odnch, B h P 938 824 (1963) K psa k C US P 3 476 955 (1969) "M sa Ch mical Co Bn b Pa en 1 168 329 (1969) ** K g,H J ( M "G us EM ( M Chmeal Co) US P 3 125 607 (1964) Ch m cal C ) U SP en 3 142 709 (1964) * McD Id D W ( M Ch m cal C ) U S P 3 125 608 (1964) G mi S Eighth World P 1 urn C K ha Cb mical 1 d tr Bntiah P u P oc ding 4, 371 (1971) 977 578 (1964) Bn h P 1 068 793 (1967) * B D H, (1950) P F G d R D, d M gd , M d W dl h P Ls Ch Ck m n A I d (L d ) 69 32 783 (1949) d Sta ks C M Co ulOIC ) US P 4 046 823 (1977) K ck M A ( Sta ff Ch mical C U S P 3 987 118 (1976) W NJ ( P Ch m R arch 1 ) U S P 3 551 506 (1970} B E Sm lley E W S mm rm W E d V JR AH d Ch cal C p ) U S P 3 987 119 (1976} d TH d K mm 1 H F ( Ow 111 ) US P 4,042 639 (1972) Rj g I H ( l.iimm C ) U S P 3 796 641 (1974) Ri g 1 H ( L mm Co US P 3 557 229 (1971) R *1 H ( S M C ( T.nmm T.umm C ) US P c ) US P 3 937 744 (1976) 3 949 010 (1976) 48 Tsa U ( L mm C ) U S P "T U ( L mm Co ) U S IP Rj g 1 H ( L mm C ) U S P Tsa U ( L mm C ) U S P 3 963 584 (1976) 3 992 460 (1976) 3 935 288 (1976) 3 985 816 (1976) "Min J D Ch m E g P g 69 (8) 71 (1973) M L d ED V yl d D M m (P t 3) J h W 1 y S I New Y k 1971 "S M V yl Chi nd d PVC M / Noy D C p 197 G m S It N w V yl Chi nd P P g VI 43 N 11 N mbe 1964 (K h ) Hyd b R w kMD / V yl P oc Hu Wd Rag f By P od t (Rh P ogil) Ch m al E g V 1 78 N 24 Oc 18 1971 "R b j d B A Rh P g I N w P f hM f V yl Chi nd M m d Chi d S1 f m Eh I 164 h ACS N 1M gNwYkAg 27 S p 1 1972 9 B kl y. J A P oc Fl w Sh /V yl Chlor d Dir Chi ti d Oxy hi Ck m al E g g V 1 73 N 24 N 21 1966 M P iv t C mm ca fmABSyk J 5 ff Ch m cal C N 29 1978 R hP Ai Oxyg ( VCM Hyyd b P st g M ch 1976 pp 85 89 P C mm ca on I in H H W II E hyl Crp N 28 1978 " V yl Chi d Hyd bP g N 1975 " EPA-450/3-73-006-C VI 3 N mb 1974 "F d al R gu J 2 1977 " EPA600/2 76*053 M b 1976 K D vid P 1 V yl Chi d H wWb Who--F Hyd b P g F b ry 1973 V yl Chi de--M su T tsu Ch m Is Hyd b P g No- mbe 1971 V 1 Chi d --PPG I d 1 Hyd b P gN m b 1975 V yl Chi de-B F Good h Ch m cal C Hyd b P g N mb 1975 V yl Chi de--Rh m P 1 SA Hyd b P gN m be 1975 V yl Chi de--(M sa C ) Hyd b P g N mb 1975 P mm ca from J S B B F G dn h Ch meal C J 5 1979 88 OCC 014107 March 1979 Hydrocarbon Processing