Industrial Catalysis: Chemistry Applied to Your Life-Style and Environment

CHAPTER

1

Industria l Catalysis : Chemistr y Applie d to Your Life-Styl e an d Environmen t BRUCE E . LEACH Research and Development Department Conoco, Inc. Ponca City, Oklahoma

I. Industrial Catalysis: Definition, Scope, and Importance . . II. History of Industrial Catalysis III. Impact on Industry and Economics IV. Impact of Industrial Catalysis on Science V. Catalysis Impact on Lifestyles A. Historical Perspective B. Impact on Environment VI. Catalysis Research A. Reasons for Doing Catalyst Research B. Hindrances to Catalyst Research C. Catalyst Manufacturing D. Metals Supply and Cost VII. Effects of Catalysts on Life-Style A. Plastics B. Transportation C. Detergents D. Food Supply E. Energy Conversion and Conservation of Resources . . F. Environmental Effects of Catalysts References

I.

1 6 12 12 13 13 14 14 14 17 17 18 20 20 21 21 21 28 28 29

Industria l Catalysis : Definition , Scope, and Importanc e

Catalysi s is a majo r facto r in industria l research , proces s selection , plan t design , an d plan t operation . Th e succes s of th e chemica l industr y is base d largel y o n catalys t technology . Th e discover y of ne w catalyst s an d thei r applicatio n hav e historicall y led t o majo r innovation s in chemica l process › ing . Market , business , an d politica l factor s combin e t o encourag e or requir e furthe r improvement s in catalys t technolog y wit h time . Applie d Industria l Catalysis , Volum e 1

1

Copyrigh t ' 1983 Academi c Press , Inc . All right s of reproductio n in an y form reserved . ISBN 0-12-440201-1

Bruce E. Leach

2

It is th e interactio n of business , markets , economics , an d politic s wit h chemistr y tha t distinguishe s industr y fro m academia . Chemica l principle s an d th e law s of thermodynamic s still apply . Th e definitio n of a catalys t is th e s a m e a materia l tha t change s th e rat e of a reactio n withou t itself bein g consumed . Catalyst s hav e n o effect on th e positio n of equilibrium , an d on e canno t mak e a reactio n procee d tha t is forbidde n b y th e law s of thermody › namics . A catalys t act s t o lower th e activatio n energ y barrie r for reaction s tha t hav e a ne t decreas e in fre e energy . Th e alternat e reactio n path s provide d b y catalyst s withi n th e law s of thermodynamic s an d chemistr y ad d valu e t o feedstoc k material s in th e refinin g an d chemica l processin g industry . Th e fundamenta l aspect s of adsorptio n on activ e sites ar e adequatel y covere d in mos t catalysi s referenc e works . Th e catalysi s scientis t shoul d b e knowledgeabl e abou t adsorptio n an d kineti c experiment s an d thei r results . Fo r example , in th e reactio n A B (Fig. 1), a serie s of step s in th e catalyti c reactio n ca n b e considered : (1) externa l diffusion , kcxt =diff kgsext ; (2) inter › na l diffusion , kint =diff ksSint ri; (3) adsorption , / c a ; d(4)s surfac e reaction , / c s; (5) desorptio n of B; (6) interna l diffusio n of B; an d (7) externa l diffusio n of B. In externa l diffusio n th e size an d shap e of th e catalys t particle , th e volume/diamete r rati o of th e reactor , an d th e spac e velocit y ar e factor s tha t influenc e th e amoun t of channeling , th e typ e of flow, th e exten t of back mixing , an d th e residenc e time . Guideline s for catalys t evaluation s in laborator y reactor s ar e given in Chapte r 3. Interna l diffusio n is dependen t on th e por e structur e of th e catalyst . Pore s ar e arbitraril y place d in thre e size categorie s accordin g t o por e diameter : micropores , < 1 5 A; mesopores , 1 5 - 1 5 0 A; macropores , > 1 5 0 A. Th e por e diamete r affect s interna l diffusion . Th e surfac e are a of man y catalyst s is primaril y interna l surface , so mos t interaction s an d collision s occu r wit h th e interna l surface . Pore s hav e a variet y of structures , an d ther e is a n effective› nes s facto r in th e equatio n expressin g interna l diffusio n rate s tha t depend s on ho w difficul t it is for reactant s t o diffus e in or out . Ofte n it is no t so critica l t o kno w th e valu e of k for interna l diffusio n a s t o kno w whethe r th e reactio n occur s primaril y on th e externa l surfac e or withi n th e pore s of th e catalys t an d t o recogniz e th e consequences . Fo r example , in a consecutiv e reactio n A+ B^C C + B ^ D

wher e C is th e desire d produc t an d D is t o b e minimized , ther e ar e tw o recognize d method s for achievin g th e desire d result . Th e por e size ca n b e kep t smal l enoug h so tha t th e reactio n occur s primaril y on th e surfac e of th e catalys t particles . Example s includ e mos t hydrocarbo n oxidatio n catalyst s wher e a decrease d rat e of reactio n du e t o reduce d surfac e are a (internal ) is

1

Industrial Catalysis

3

A A

Step 1

Step 2

A

Fig. 1 . Steps in the catalytic reaction.

Step 3

Step 4

acceptabl e t o gai n selectivit y of product . Specific example s ar e given in Chapte r 8. Alternatively , a larg e por e size ca n b e selecte d so tha t ther e is facile diffusio n ou t of th e por e syste m befor e C ca n reac t furthe r wit h B. Thi s approac h reduce s th e interna l surfac e area , wherea s in th e cas e of ver y smal l pore s th e interna l surfac e is inaccessible . Anothe r exampl e of por e size importanc e is foun d in th e hydrodesulfuri zatio n of heav y crud e oils. Rapi d catalys t deactivatio n is associate d wit h particula r por e sizes, an d approache s base d on support s of eithe r smal l [ 1 ] or larg e [2] por e diamete r hav e bee n developed . Theor y ha s ofte n c o m e afte r discovery . Ideally , th e objectiv e is t o desig n a catalys t base d on first principles . Thi s objectiv e is no t yet withi n th e capabilit y of catalysi s science . In addition , th e complicatin g facto r of eco› nomic s mus t b e addresse d in th e industria l setting . Optimizatio n of th e adde d valu e t o feedstock s require s a knowledg e an d interactio n of chemistr y an d economics . Thi s is a specia l challeng e t o th e scientis t or enginee r in industria l catalysis . Bot h catalyti c scienc e an d eco› nomic s chang e wit h time . Thi s ensure s tha t ne w an d improve d catalyst s will continu e t o b e developed . Thes e catalyst s will b e use d t o proces s histori c an d ne w feedstocks . Th e variable s encompasse d b y ne w catalysts , ne w an d modifie d processes , an d th e changin g economic s of alternat e feedstock s take n togethe r wit h politica l an d environmenta l restraint s mak e for man y excitin g an d challengin g technica l endeavor s withi n th e industry . Th e scop e of catalysi s in industr y range s fro m theoretica l prediction s of catalyti c activit y t o th e ar t of catalys t forming . It include s bot h wor k on th e frontier s of catalysi s scienc e an d th e carefu l recommendatio n of a particula r commercia l catalys t tha t meet s a specific customer’ s feedstoc k an d reacto r desig n criteria . It include s catalys t regeneration , testing , an d qualit y control , as well a s catalys t selection . Findin g an d removin g a catalys t poiso n presen t

4

Bruce E. Leach

in a par t per millio n or even a par t per billio n quantit y in th e feedstoc k present s its own set of analytica l an d chemica l challenges . A majo r chang e in th e practic e of catalysi s in th e pas t severa l decade s ha s bee n th e concerte d applicatio n of analytica l technique s t o catalysts . A numbe r of thes e technique s an d thei r applicatio n in catalysi s ar e given in Tabl e I. Industria l catalysi s provide s a n opportunit y for technica l exchang e wit h man y disciplines . Moder n catalyst s mus t rel y on th e integratio n of a broa d rang e of technica l expertis e an d experimenta l capabilities . Chemica l engi › neering , organi c chemistry , inorgani c chemistry , coordinatio n chemistry , analytica l chemistry , an d surfac e scienc e ar e all essentia l in understandin g an d developin g catalyst s (Fig. 2). At a tim e at whic h th e conversio n t o SI unit s is in progres s an d wit h olde r

TABL E I Analytica l Technique s Frequentl y Used in Catalysi s Characterization

Technique

Bulk

Surface area analysis Pore volume analysis X rays Scanning electron microscope Electron microprobe Infrared spectroscopy Elemental analysis Surface acidity Loss on ignition Thermal gravimetric analysis Density Bulk crushing strength Particle size analysis NMR ESR X-ray scattering Laser Raman spectroscopy Extended x-ray adsorption fine-structure microscopy (EXAFS) X-ray photoelectron spectroscopy (ESCA) Scanning electron microscope (SEM) Auger electron spectroscopy (AES) Ion-scattering spectroscopy (ISS) Secondary ion mass spectroscopy (SIMS) Magnetic susceptibility Selective surface area Selective adsorption Programmed temperature desorption

Surface

1

5

Industrial Catalysis

Surface Science

Chemical Engineering

T

\ /

\ Reactor Design

/

\

Theory of Adsorption

\

/

\

/

Process Economics \

/ Surface Analysis Development

\

/

Pilot Plants

/

\ Analytical Chemistry

Catalyst Characterization

Catalyst Supports

Feed Stock and Product

Promoters

Metal Complexes / / Theory of Metal ton Coordination /

Coordination Chemistry

Inorganic Chemistry

Solvent Selection \

\ Feedstock Preparation \

Organic Chemistry

Fig. 2. Technical dependence of industrial catalysis.

unit s still widel y used , ther e is a communicatio n problem . Thi s boo k reflect s problem s tha t will continu e for man y years . Fo r thi s reaso n a c o m m o n nomenclatur e an d unit s tabl e is provide d in th e Appendi x t o thi s volume . Althoug h th e reade r ma y find it confusin g t o see temperatur e in degree s centigrade , degree s Farenheit , an d kelvin s all in th e sam e chapter , thi s is th e realit y o f th e situatio n on e is faced wit h in industry . Th e scop e of catalyst s in th e chemical s industr y is so extensiv e tha t it is rar e t o find a researc h proble m tha t canno t b e redefine d in term s of catalysis . Thu s althoug h th e researc h proble m titl e an d th e objectiv e ma y b e state d in busines s an d economi c language , th e scientifi c methodolog y require d for achievin g th e projec t goal s ofte n involve s th e practic e o f catalyti c science . Th e majo r innovation s in th e petrochemica l industr y in th e pas t 25 yr hav e involve d breakthrough s in catalys t research . I n mos t industria l researc h problems , catalys t selectio n or improvemen t is th e ke y t o th e succes s of th e project . Thi s heav y dependenc e on catalysi s ca n b e seen in bot h explorator y an d applie d research .

6

Bruce E. Leach

Th e shutdow n of a chemica l plan t becaus e of catalys t problem s is a crisi s situation . Thi s subjec t will b e develope d late r in th e chapter . Timel y actio n is possibl e onl y if th e catalysi s scientis t ha s th e backgroun d an d expertis e t o diagnos e an d prescrib e a remedy . Considerabl e effor t is devote d in industr y t o evaluatin g change s in catalysts , feedstocks , an d proces s condition s (in › cludin g upse t conditions ) an d thei r effect on catalys t lifetime , selectivity , an d productivity . Losse s fro m th e shutdow n of larg e chemica l plant s ca n b e man y hundre d thousan d dollar s per day . Wit h thi s muc h at stake , ther e is justificatio n for considerabl e research . Operatin g department s ofte n suppor t extensiv e pilotin g facilitie s afte r plan t start-u p a s well as befor e plan t constructio n t o provid e insuranc e tha t th e downtim e at a larg e facilit y will b e minimal . Th e speed y resolutio n of catalyst-relate d problem s at operatin g facilitie s ma y no t lea d t o publications , patents , an d recognitio n fro m th e scientifi c community , bu t ther e is a sens e of persona l accomplishmen t an d recognitio n fro m catalys t marketin g managers , chemica l plan t managers , an d researc h directors . It is th e profitabilit y of curren t chemica l plant s tha t justifie s futur e expansio n an d researc h in industria l catalysis .

II .

Histor y of Industria l Catalysi s

A catalys t wa s use d industriall y for th e first tim e b y J . Roebuc k in th e manufactur e of lea d chambe r sulfuri c aci d in 1746. At tha t tim e Berzeliu s ha d no t yet use d th e wor d "catalysis" tha t cam e in 1836. Earl y develop › men t occurre d in inorgani c industria l chemistr y wit h processe s for carbo n dioxide , sulfu r trioxide , an d chlorin e productio n in th e 1800s. P. Sabatie r an d R. Sendere n in 1897 foun d tha t nicke l wa s a good hydrogenatio n catalyst . P. Sabatie r [3], in hi s boo k Catalysis in Organic Chemistry, gives a n excellen t perspectiv e of catalysi s in th e earl y 1900s. It wa s a tim e whe n answer s t o question s abou t transitio n states , adsorption , an d mechanism s wer e difficul t t o obtain , an d yet Sabatie r wa s askin g th e righ t questions . Hi s ide a of temporar y unstabl e intermediat e compound s bein g forme d in cata › lysis wa s correct . H e lamente d th e unsatisfactor y stat e of knowledge , yet th e perio d 1 9 0 0 - 1 9 2 0 sa w advance s in man y areas . It wa s th e tim e of Ostwald , Gibbs , Bosch , Ipatief , Einstein , Planck , Bohr , an d Rutherford , amon g others . Scientist s suc h a s E. Fischer , Kekule , Claisen , Fittig , Sandmeyer , Faworsky , Deacon , Dewar , Friedel , an d Craft s ha d mad e thei r contribution s t o organi c chemistr y jus t prio r t o 1900. Initiall y mos t catalyst s wer e relativel y pur e compounds . Multicomponen t catalyst s wer e studie d afte r 1900 at Badisch e Anilin - & Soda-Fabri k (BASF) . Habe r discovere d ammoni a synthesi s at hig h pressur e usin g osmiu m or uraniu m catalysts . Bosch an d associate s at BASF develope d th e us e of

1

Industria l Catalysi s

7

magnetit e promote d wit h alumin a an d alkali . Thi s researc h projec t is describe d b y A. Mittasc h [4] in detail . Th e ammoni a synthesi s industr y is base d on promote d iro n catalysts . A catalys t wa s develope d t o suppl y hydroge n via th e wate r ga s shift reactio n b y th e BASF group . Bosch at BASF nex t attempte d t o reduc e carbo n monoxid e wit h hydroge n at hig h pressure s t o produc e alcohol s an d highe r hydrocarbons . Thi s wor k led t o methano l synthesi s usin g alkali-promote d zin c oxid e plu s chromiu m oxid e in 1923. Syntheti c hydrocarbon s wer e mad e fro m synthesi s ga s in 1927 b y Fische r an d Tropsch . Th e adsorptio n of reactant s on catalys t surface s wa s firs t though t t o b e importan t in th e 1 9 0 0 - 1 9 2 0 period . Langmuir-Hinshelwoo d an d R i d e a l Ele y mechanism s wer e proposed . Th e adsorptio n of gase s b y solid s an d particularl y th e adsorptio n of hydroge n presente d man y unknowns . Fo r example , it wa s no t know n wh y th e quantit y of hydroge n adsorbe d varie d or indee d ho w a substanc e lik e palladiu m coul d adsor b so muc h hydrogen . A majo r developmen t in th e 1920s occurre d whe n H . S. Taylo r distin › guishe d amon g activate d adsorption , chemisorption , an d physica l adsorp › tion . H e als o develope d th e concep t of activ e centers . In th e 1930s a numbe r of advance s occurre d tha t aide d in th e stud y of adsorption : (1) Isotope s becam e availabl e in 1933. (2) Brunaue r an d Emmet t discovere d ho w t o measur e th e surfac e are a an d por e geometr y of catalyst s usin g physica l adsorption . (3) Beeck use d evaporate d meta l films for basi c catalyti c studies . (4) Robert s mad e tungste n filaments fo r th e firs t tim e "clean " sur › faces coul d b e studie d becaus e tungste n coul d b e heate d ho t enoug h t o clea n meta l surfaces . (5) Ridea l mad e othe r meta l filament s an d films. Adsorptio n studie s dominate d catalysi s scienc e for a tim e whil e th e ne w technique s wer e bein g applied . In th e 1950s attentio n shifte d t o th e natur e of th e interaction s betwee n th e activ e cente r an d th e adsorbate , an d toda y spectroscopi c method s continu e t o revea l informatio n abou t bondin g in catalysts . A surve y of catalyti c developmen t is given in Fig . 3. Th e pas t 60 yr hav e bee n ver y activ e one s in th e developmen t of ne w catalyti c processes . A list [5] of th e mor e recen t of thes e ha s bee n compile d b y Halco n Internationa l (Tabl e II) . Othe r significan t catalys t development s includ e th e famil y of ZS M zeolite s discovere d b y Mobi l Oi l Corporation , th e carbonylatio n of methano l t o aceti c aci d practice d b y Monsant o Company , an d a ne w generatio n of catalyst s for refining , polyolefins , oxychlorination , etc . Fe w heterogeneou s catalys t composition s remai n constan t for a s lon g a s a

1750 1800 1850 1725 1775 1825 1875 S0 3 NO

C 0 SQ3 2 Pt Cl 2 Pt CuCI

2

1900 1925

1950

HN0 NH3 3 Fe Pt

H 0 22 Rd

H 2 Ni

Fat hydrogenation CH3OH NI Zn0-Cr 0

23

1975

I

-4H6 R^OrCr^-AfeOs

Olefins+CO* Aldehydes-*Alcohols (Oxo process) Polymerization

Phthalic acid Pt

Z < CD or o

Peroxide AIR 3 Li TiCI Polyurethanes

Na

oo

CH3CH O CO Insertion PdCI 2 CH3COOH CH2=CHCN (acrylonitrile) Anchored B1-M0-PO 4 enzymes Aromatics by I hydrodealkylation Alcohols Cr 03-Al2p3 Metal complexes

2

Third generation Zlegler - N a t t a

3

S M Alkylation Hydrocracklng H S 0 HF| 2 4 , , Cracking Coal + H 2 |C0 +• H^liquid hydrocarbons molecular sieves molecular sieves Co-Th0 ~Si02| Liquid 2 Catalytic hydrocarbons Reforming Cracking muffler Fe 03'MoS multimetals Si0 -AI 03 2

2

1990

1980

T

Z

2 2

Polymerization H P0 3 4 Hydroforming |Mo03-AI 0 Pt-Al 03|

23

Fuel cells

Synthetic fuels

2

Fig. 3. Surve y of catalyti c development . Adapte d with permissio n fro m Kirk-Othme r Encyclopedi a of Chemica l Technology , Thir d Edition , Joh n Wiley & Sons, Inc .

TABLE II Chemical Processing Developments of the Last 25 Yr as Compiled by Halcon International" Company * Approximat e dat e

Produc t

Befor e 1957

Isocyanate s - urethane s

1953+ 1955 1958 1958 1958+

Ammoni a Malei c anhydrid e High-densit y polyethylene , polypropylen e a-Olefin s Terephthali c aci d

1959

Acetaldehyd e

1960-1970 1964 1965+

Oxidatio n alcohol s cyclohexanol , cyclohexan on e (for nylon ) Viny l chlorid e

1965 1965

Acrylonitril e H M D A (for nylon )

1967+

Viny l acetat e

1968

Aceti c aci d

Developmen t Urethane s an d foam s (polyethe r polyols , one sho t foam , etc. ) High-pressur e syntheti c ga s High-yiel d benzen e oxidatio n N e w catalyst s N e w catalyst s Air oxidatio n of p-xylen e pur e produc t Vapo r phas e ethylen e oxidatio n Improve d catalyst s Cyclohexan e oxidation , bori c syste m Oxychlorinatio n of ethylen e Propylen e ammoxidatio n Acrylonitril e electrohydrodi merizatio n Ethylen e + aceti c aci d + 0 , 2 vapo r phas e High-pressur e metha › no l + C O

Chemica l Baye r

Oi l Wyandott e

—

—

—

Montecatin i

Phillips , Avisu n

Ethy l Halco n

Gulf , C o n o c o

Wacke r U C C , IC I

Proces s engineerin g Houdr y

Pullman , Kellog g Halco n

— —

—

Amoc o

—

Hoechs t

—

Exxon , Shel l

—

—

Goodrich , Monsanto , Stauffer , PP G

—

Halco n

—

Monsant o

—

— —

Bayer , Celanese , Hoechst , USI BASF , D u P o n t

—

—

—

—

—

SOHI O

Tabl e II (continues )

TABLE II

(Continued) Company*

Approximate date

Product

Development

1969 1969

Propylene oxide, glycol, TBA Phthalic anhydride Acrylates

Epoxidation with hydroper­ oxide High-yield oxylene oxid. Propylene oxidation

1969

Quiana

1970+ 1970 1970 1972 1972

Ethylene oxide p-Xylene Methanol HMDA (for nylon) Styrene and propylene oxide Acetic acid Maleic anhydride Kevlar Polypropylene Ethylene glycol (and vinyl acetate)

From cyclododecane oxidation Catalyst improvements Recovery by adsorption Low-pressure CO + H 2 Butadiene + HCN Epoxidation with hydroper­ oxide Low-pressure methanol + CO From butane High-tensile fiber Vapor phase Via acetoxylation

1969+

1973 1974+ 1974 1974 1978

a b Reprinte d

Chemical

Oil

Process engineering Arco, Halcon

BASF Celanese, Rohm & Haas, UCC DuPont Shell, UCC

BP, SOHIO Halcon Halcon UOP

ICI DuPont Arco, Halcon Monsanto Amoco, Monsanto DuPont BASF

Halcon

Halcon

_

with permissio n of th e Halco n SC Group , Inc . BASF, Badisch e Anilin - & Sodi-Fabrik ; ICI , Imperia l Chemicals ; PPG , Pittsbur g Plat e Glass ; UCC , Union Carbid e Corporation ; UOP , Universa l Oil Products .

1

Industrial Catalysis

11 TABL E II I

Example s of Titanium-Base d Polyethylen e Catalys t Development s Catalyst TiCl + AlEt

4

Improvement* Basic catalyst, Ziegler and co­ workers First-generation commercial catalyst Activity increase of ~ 10 fold Supported titanium trichloride catalyst, — 13.6 kg PE/hr atm eth­ ylene g Ti 132 kg PE/hr g T i

3

TiCl -iAlCl 3 3 TiCl • ^A1C1 + electron donor 3 3 Mg(Cl)OH + TiCl

4

TiCl + (MgBuCl + methylhy4 dropolysiloxane)

Reference [6] [7] [8] [9]

[10]

a

PE , Polyethylene .

decade . A n excellen t exampl e is provide d b y polyolefi n catalyst s base d o n titaniu m trichloride . Thes e catalyst s ar e n o w in wha t is calle d th e thir d generation . Th e histor y of thei r developmen t is briefl y summarize d wit h example s in Tabl e III . Man y permutation s of eac h generatio n of catalyst s exist , a s evidence d b y th e larg e numbe r of patent s publishe d b y competin g TABL E IV Some Chemical s Produce d from Ethylen e and Propylen e Ethylene Ethylene + oxygen /

acetic acid

—- acetaldehyde

\

butanol —• octanol Ethylene 4- oxygen —* ethylene oxide —* ethylene glycol Ethylene -I- acetic acid —* vinyl acetate Ethylene + chlorine —-> vinyl chloride Ethylene + oxygen -I- carbon monoxide —* acrylic acid Propylene Propylene + oxygen —* acetone Propylene + alcohol —* acrylic ester Propylene -I- ammonia —* acrylonitrile Propylene + air or oxygen —+ acrolein Polymers based on ethylene or propylene Polyethylene Polypropylene Styrenes Acrylics cis-1,4-Polyisoprene Polyvinyl chloride cis-1,4-Polybutadiene

12

Bruce E. Leach

companies . Simila r example s coul d hav e bee n chose n in refinin g or for othe r processes .

III .

Impac t on Industr y and Economic s

Th e chemica l industr y ha s grow n in recen t decade s an d significantl y affect s th e economy . Catalyst s an d th e product s derive d fro m catalyti c reaction s directl y or indirectl y accoun t for 10 t o 15% of th e gros s nationa l produc t (GNP ) of th e Unite d States . Th e tw o majo r factor s in th e rapi d developmen t of th e chemica l industr y sinc e 1950 hav e bee n th e low-cost petroleum-base d suppl y of ethylen e an d propylen e ra w material s an d th e developmen t of oxidatio n an d polymerizatio n catalysts . Th e diversit y of chemical s pro › duce d fro m ethylen e an d propylen e is illustrate d in Tabl e IV.

IV.

Impac t of Industria l Catalysi s on Science

Th e beginning s of industria l catalysi s wer e application s of basi c research . Th e developmen t of catalysi s ha s bee n base d on scientifi c innovation . Th e objectiv e ha s bee n t o desig n catalyst s of hig h activit y an d selectivit y base d on scientifi c theor y rathe r tha n tria l an d error . Thi s ha s encourage d th e devel › opmen t of theorie s explainin g catalysi s in term s of activ e sites, geometry , meta l properties , etc . Th e objectiv e of a complet e understandin g ha s bee n mos t elusive , an d catalysi s remain s bot h a n ar t an d a science . Basi c researc h ha s led t o numerou s models , an d the y hav e bee n challenged , refined , an d sometime s discarded . On e doe s no t hav e t o understan d wh y a catalys t work s t o tak e commercia l advantag e of it, bu t it usuall y help s t o hav e a fundamen › ta l understandin g of th e activ e site an d th e interaction s of th e reactant s an d product s wit h th e sites. Som e commercia l system s ar e so comple x tha t the y presen t challenge s t o scientifi c analysi s tha t hav e yet t o b e solved even afte r 50 yr . Industr y an d academi a coul d bot h benefi t b y increase d interactio n in th e catalysi s area . Ther e ar e man y simpl e chemica l synthesi s reaction s tha t wer e studie d inadequatel y or befor e moder n instrumentatio n wa s available , an d som e of thes e ca n yield interestin g ne w aspect s of chemistry . An exampl e is pheno l methylatio n [11] over a n alumin a catalys t t o yield primaril y o-cre sol, 2,6-xylenol , an d 2,3,6-trimethylphenol . It wa s originall y believe d tha t 2,6-xyleno l first isomerize d t o 2,3-xyleno l or 2,5-xyleno l whic h the n reacte d wit h methano l t o for m 2,3,6-trimethylphenol . Whe n th e reactio n wa s

1

Industrial Catalysis

13

investigate d unde r trickl e be d reactio n condition s at temperature s belo w th e isomerizatio n range , it wa s discovere d tha t th e selectivit y for 2,3,6-trimeth › ylpheno l fro m 2,6-xyleno l methylatio n increased . Th e reactio n is no w understoo d as occurrin g via a n ips o mechanis m [Eq . (1)]. OH CH

3

i

CH

OH

OH

3

CH CH QH 3 ALO

A

3 CH 3

I

OH CH

3 (1)

H

Bot h industr y an d universitie s hav e man y c o m m o n objective s tha t fur › the r catalysi s science . Thes e includ e th e followin g manifestations : trainin g of catalysi s scientists , developmen t of center s of catalysis , publicatio n of book s an d papers , consulting , catalysi s meeting s an d conferences , seminars , researc h grants , an d sharin g of researc h facilities .

V.

Catalysi s Impac t on Life-Styl e A.

HISTORICA L PERSPECTIV E

Th e impac t of industria l chemistr y an d catalysi s on life-styles durin g thi s centur y is dramatic . In recen t time s chemistr y ha s receive d som e negativ e connotation s becaus e th e potentia l for detrimenta l effects on th e environ › men t ha d no t bee n adequatel y appreciate d in a few widel y publicize d instances . However , few peopl e woul d lik e t o d o withou t th e industria l product s tha t hav e so change d civilizatio n in th e twentiet h century . Thes e impact s hav e bee n mos t eviden t in th e followin g areas : (1) Transportation fuel , tires , material s of constructio n (plastics) , an d pollutio n control ; (2) Food packaging , fertilizers , an d insecticides ; (3) Clothing nylon , polyester , dacron , rayon , an d orlon ; (4) Detergent s an d cosmetics biodegradabl e surfactants ; (5) Houseware s an d furniture materia l of constructio n (plastics) , in › sulation ; (6) Construction carpets , plasti c pipes , insulation , an d engineerin g plastics ; an d (7) Toys plasti c construction . Approximatel y 85% of organi c industria l chemical s on a weigh t basi s go int o plasti c applications . Th e rol e of catalyst s in th e preparatio n of monomer s

Bruce E. Leach

14

and/o r polymer s will b e describe d in Sectio n VII . Polymerizatio n catalyst s ar e th e subject s of Chapte r 6 in thi s volum e an d Chapte r 5 in Volum e 3. B.

IMPAC T O N E N V I R O N M E N T

Industria l catalysi s ha s responde d t o problem s of pollutio n control . Cata › lysts ar e use d t o remov e hydrocarbons , carbo n monoxide , an d nitroge n oxide s fro m wast e an d exhaus t gases . Th e fundamenta l proble m is t o develo p chemica l processe s tha t minimiz e or eliminat e pollutio n in th e manufacturin g process . Catalyst s will pla y a vita l rol e in th e developmen t of thes e nonpollutin g processes . A majo r challeng e will b e t o solve th e environ › menta l problem s associate d wit h th e chang e in chemica l feedstock s fro m petroleu m t o coa l in th e nex t century . Catalyst s themselve s ca n pos e environmenta l problem s in manufactur e an d disposal . Thes e aspect s ar e considere d in Sectio n VI.C .

VI. A.

Catalysi s Researc h

REASON S FO R D O I N G CATALYS T RESEARC H

Ther e ar e numerou s reason s for industria l suppor t of catalysi s research . The y includ e th e followin g objectives : basi c understandin g of chemistry , creatio n of ne w catalysts , competiv e advantag e (marke t shares) , paten t position , solvin g plan t problems , an d improvin g profits . A n understandin g of th e chemistr y an d engineerin g detail s of a chemica l proces s is importan t t o a compan y tha t use s or plan s t o utiliz e th e process . G o o d scienc e build s th e reputatio n of th e compan y an d its scientists . Thi s reputatio n is valuabl e in recruitin g an d in custome r relations . A standar d of excellenc e in researc h is desirabl e for th e moral e of th e scientist s an d thei r persona l development . A measur e of th e importanc e associate d wit h basi c catalysi s researc h is th e numbe r of scientifi c paper s publishe d b y industria l scientist s an d th e excellen t suppor t given b y researc h director s t o publica › tion s suc h a s thi s work . Catalys t developmen t ca n b e merel y a searc h for a catalyst , bu t a highe r objectiv e ha s alway s bee n t o creat e a catalys t base d on scientifi c principles . Progres s is bein g mad e towar d thi s objectiv e an d is fostere d b y th e basi c catalysi s researc h funde d b y corporations . A ne w or improve d catalys t is ofte n th e basi s of a competitiv e manufac › turin g cost advantage . Contribution s t o a lower manufacturin g cost ca n com e fro m an y of th e following : (1) reduce d equipmen t costs , (2) reduce d

15

1 Industria l Catalysi s

feedstoc k costs , (3) lowere d utilit y costs , (4) improve d strea m factor , (5) increase d by-produc t credit s or reduce d by-produc t debits , an d (6) de › crease d catalys t usage . Catalys t cost s themselve s ar e usuall y a n insignifican t portio n of manufac › turin g costs , typicall y rangin g fro m 0.1$ t o severa l cent s per poun d for commodit y chemicals . Th e competitiv e advantag e ma y als o tak e th e for m of a superio r produc t becaus e of th e purity , isome r distribution , etc. , of th e final product . In th e catalys t preparatio n industr y itself ther e is intens e competitio n t o develo p superio r catalysts . Becaus e of th e leverag e create d b y a superio r catalys t in regar d t o manufacturin g costs , a prove n high-performanc e catalys t ofte n capture s a sizabl e marke t share . If it is no t continuall y improve d b y research , however , it will b e challenge d b y a superio r competitiv e produc t an d rapidl y lose it s marke t share . Thus , researc h in catalysi s is initiate d t o preserv e or captur e a particula r marke t shar e in th e catalys t an d chemical s busines s area . Technica l informatio n is a valuabl e asset t o a compan y an d is develope d at considerabl e expense . It ca n b e kep t a s a trad e secre t or patented . A paten t gives th e owne r th e righ t t o exclud e other s fro m making , using , or sellin g th e inventio n for a perio d of tim e 17 yr in th e Unite d States . Patent s serv e no t onl y t o protec t operation s bu t ma y b e license d or sold t o othe r companie s for significan t income . A paten t ma y cover a proces s or method , a produc t or composition , or a n apparatus . Becaus e of thei r nove l compositio n or metho d of preparatio n catalyst s ar e ofte n patented . In additio n t o bein g novel , a n inventio n als o mus t hav e utilit y an d no t b e obvious . Becaus e catalysi s is ofte n a n ar t a s well as a science , patent s base d on catalysi s ar e no t obviou s an d utilit y is eas y t o demonstrate . Composition-of-matte r patent s ar e th e mos t valuable . A n excellen t exampl e of a paten t excludin g other s fro m practic e is Mobi l Oi l Corporation’ s composition-of-matte r paten t on ZSM- 5 shape-selectiv e zeolit e [12]. Th e paten t describe s " a crystallin e aluminosilicat e zeolit e havin g a compositio n in term s of mol e ratio s of oxide s as follows: 0.9 – 0.2M O : A 1 0 : F S i 0 : Z H 0 ,

2/

23

2

2

wherei n M is at least on e catio n havin g a valenc e n, Y is at least 5 an d Z is betwee n 0 an d 40, sai d aluminosilicat e havin g th e x-ra y diffractio n line s of Tabl e I of th e specification. " Suc h a paten t place s th e owne r in a ver y favorabl e licensin g position . Patents , lik e publication s in academia , ar e a statu s symbo l in industria l researc h for bot h th e individua l an d th e company . Catalyst-relate d patent s ar e a sizabl e fractio n of th e chemistr y patent s in th e Central Patents Index of Derwen t Publications , Ltd. , an d th e U.S. Patent Gazette.

16

Bruce E. Leach

Catalysi s researc h ma y b e defensiv e in nature . Th e objectiv e ma y b e t o ensur e continue d operatio n of a commercia l facility . Thi s ma y b e don e b y catalys t an d feedstoc k evaluatio n t o solve plan t operationa l problem s befor e or a s the y arise . Th e incentiv e is grea t t o solve thes e problem s rapidly . Downtim e at a larg e reacto r facilit y is wort h 2 - 3 man-year s of researc h tim e per day . Catalys t researc h is neede d t o give th e scientis t th e backgroun d dat a require d t o diagnos e plan t operationa l problem s rapidly . Th e ris k of no t doin g catalys t researc h is simpl y to o hig h for a plan t manage r t o accep t on a long-ter m basis . Anothe r ite m leadin g t o increase d profitabilit y is improve d catalys t life. In Fig. 4 a n exampl e is given of a 1-billion-lb/y r chemical s plan t wher e catalys t change s requir e a 2-week shutdown . A stud y of th e annualize d cost s indicate s ther e is a variabl e retur n dependin g on th e curren t stat e of th e art . Ther e is no t muc h incentiv e t o develo p a ne w catalys t for th e applicatio n

1

17

Industrial Catalysis

chose n for compariso n if th e presen t catalys t ha s a 9-mont h life an d th e ne w catalys t ha s a 12-mont h lifetime . However , if th e state-of-the-ar t catalys t ha s a 4- t o 6-mont h life range , th e incentiv e for catalys t researc h is great . Th e othe r factor s importan t t o th e particula r analysi s includ e (1) downtim e for catalys t change , (2) size of th e commercia l unit , (3) catalys t replacemen t costs , (4) th e valu e of lost productio n capacity , (5) marke t conditions , an d (6) a n estimat e of th e difficult y of preparin g a superio r catalyst .

B.

H I N D R A N C E S T O CATALYS T RESEARC H

Catalysi s is a complicate d ar t an d science . Althoug h th e benefit s of catalysi s researc h hav e bee n enumerated , ther e ar e a numbe r of hindrance s t o industria l catalysi s research . Eac h corporatio n ha s evolved a polic y consisten t wit h its objective s an d limitations . Th e stud y of catalysi s require s a sizabl e technolog y base , bot h in scientifi c expertis e an d instrumentatio n techniques . Ther e is a wid e spectru m of involvemen t dependin g primaril y on a corporation’ s decisio n whethe r t o develo p its own catalys t technolog y or t o licens e thi s technolog y fro m others . Th e evaluatio n of technolog y require s less labor , an d license s ar e generall y availabl e for commodit y chemical s synthesi s at reasonabl e rates . N e w product s requir e a greate r effort , in th e are a of catalys t development . Corporation s wit h a reputatio n for developin g ne w catalyst s an d product s usuall y hav e a large r researc h staf f an d a greate r variet y of sophisticate d spectroscopi c instrumentatio n technique s availabl e a s resource s tha n cor › poration s tha t licens e technology . However , size alon e doe s no t ensur e innovation , an d even smal l researc h organization s ca n develo p specific catalysts . Th e tw o extreme s in catalysi s researc h objective s hav e bee n presented . Ther e is a continuu m of alternative s betwee n theoretica l wor k on ne w catalyst s an d th e decisio n t o evaluat e onl y commerciall y availabl e catalysts . Catalys t manufacturin g companie s ofte n wor k wit h a n invento r t o commer › cializ e th e catalys t recipe . Renta l of spectroscopi c instrumen t facilitie s is possibl e whe n th e workloa d doe s no t justif y th e capita l expenditure . Th e wid e rang e of expertis e neede d t o creat e a catalys t is a hindranc e t o catalys t research , bu t selecte d contrac t researc h ca n minimiz e th e limitation s of resources . C.

CATALYS T

MANUFACTURIN G

Th e develop-or-bu y consideratio n regardin g catalyst s depend s on whethe r th e invento r ha s a larg e volum e deman d an d facilitie s for catalys t

18

Bruce E. Leach

manufacturing . Som e oil an d chemica l companie s hav e gon e int o th e catalys t preparatio n business . Other s wh o determine d the y coul d no t eco› nomicall y produc e catalyst s themselve s hav e retaine d th e service s of a n outsid e manufacture r wh o make s proprietar y catalysts . Thi s is develope d in dept h in Chapte r 2. A list of companie s wh o activel y sell catalyst s in th e Unite d State s is given in Tabl e V. Catalys t companie s specializ e in particula r catalyst s for whic h the y hav e technica l expertis e an d a historica l marke t position . Catalys t companie s dea l wit h factor s tha t hav e n o counterpar t in laborator y preparations : scale-u p of operations precipitation , mixing , filtration , drying , forming , an d calcination ; continuou s uni t operations ; energ y conservatio n an d envi › ronmenta l control ; an d optimu m us e of productio n facilities .

D.

METAL S SUPPL Y A N D COS T

Catalys t selectio n an d developmen t mus t includ e a n evaluatio n of metal s suppl y an d cost . Thi s is particularl y tru e of preciou s an d strategi c minerals . As example s th e compositio n of reformin g catalyst s is adjuste d t o provid e th e mos t cost-effectiv e catalys t composition , an d nicke l rathe r tha n th e mor e expensiv e cobal t is no w th e choic e of refinerie s in th e hydrodesulfuri zatio n of crud e oil. Majo r source s of strategi c material s ar e show n in Fig. 5. Th e material s mos t critica l t o th e catalys t industr y tha t ar e on th e strategi c list ar e chromium , cobalt , manganese , an d platinu m grou p metals . In th e desig n an d selectio n of a commercia l catalys t on e mus t conside r th e volum e of meta l t o b e use d in relationshi p t o th e suppl y an d th e natura l mi x

TABLE V Majo r Catalys t Companie s in th e Unite d State s Activated Metals Air Products and Chemicals American Cyanamid Armak Chemical Division BASF Wyandotte Calsicat Division, Mallinckrodt Dart Industries Davison Chemical Division, W. R. Grace Degussa Corporation Englehard Minerals and Chemicals Corporation Filtrol Halcon Catalyst Industries

Haldor Topsoe, Inc. Harshaw Chemical Katalco Matthey Bishop, Inc. Montedison, USA, Inc. Nalco Chemical Oxy-Catalyst, Inc. Shell Chemical Stauffer Chemical United Catalysts, Inc. Universal Oil Products, Inc.

Canada Nickel Copper Asbestos Niobium Gallium Tantalum Zinc Cadmium Cesium

Philippines Chromium ^

VY^ \JCr

^

\

Malaysia Tantalum

Tn i

UNITED STATES Copper Bauxite Phosphorus Mexico Uranium Fluorspa Zinc Strontium Gold Zinc Antimony Silver

>\T^ ~ New Caledonia Nickel

Cadmium

Jamaica Bauxite Aluminum Bolivia Tin Antimony |

West Germany Gallium K Cesium Platinum Belgium-Luxembourg Cobalt Antimony France Manganese Italy Fluorspar Brazil Niobium Manganese Tantalum Gabon Manganese Botswana Chromium Diamonds South Africa Chromium Manganese Vanadium Platinum Fluorspar

1

, Zaire 'Cobalt Copper Diamonds Tin Niobium Tantalum Gold Tungsten Zambia Cobalt Gold Zimbabwe Manganese Chromium Nickel Copper Gold Asbestos

Fig. 5. Sources of strategic materials. Adapted with permission from C & EN, May 11, 1981, p. 21. Copyright 1981 American Chemical Society 1981.

Bruce E. Leach

20

of th e metal s mined . Fo r example , th e norma l mi x of platinu m t o rhodiu m is 1 9 : 1 . A majo r proble m in three-wa y catalyti c converter s for automobil e exhaus t treatmen t ha s bee n tha t th e optimu m rati o of platinu m t o rhodiu m for thi s applicatio n is closer t o 5 : 1 . Majo r us e of suc h a mixtur e woul d hav e resulte d in a n overproductio n of platinu m an d a n intens e shortag e of rhodium . A solutio n ha s bee n t o conside r th e converte r as havin g tw o parts : on e sectio n wit h a hig h Pt : R h rati o an d th e othe r wit h a lower Pt : R h ratio . Overal l ratio s mor e in balanc e wit h th e natura l mi x ar e thu s obtained . Preciou s metal s ar e recycled , bu t mos t bas e meta l catalyst s ar e not , includin g som e tha t ar e quit e hig h in nickel , cobalt , copper , an d chromium . Th e first proble m in recyclin g is th e presenc e of residua l organic s on th e spen t catalyst . Th e remova l of organic s add s anothe r cost t o th e recover y proces s bu t is generall y require d becaus e the y interfer e in aqueou s meta l ion separatio n scheme s an d ar e a wate r pollutio n problem . Th e secon d facto r limitin g meta l recycl e is tha t man y catalyst s contai n mixture s of metal s no t foun d coexistin g in th e natura l ore s routinel y processe d t o yield a particula r metal . An exampl e is coppe r chromit e catalyst . A thir d facto r is volum e an d th e nee d for a transportatio n networ k t o collect catalyst s for metal s recovery . Th e spen t catalyst’ s geographica l dis › persio n is a primar y facto r in potentia l metal s recover y fro m automobil e exhaus t catalysts . Th e quantit y of preciou s meta l per automobil e is abou t 0.05 tro y oz. Recover y fro m alumin a support s woul d b e practica l if ther e existe d a collectio n an d transportatio n syste m tha t coul d delive r spen t catalys t container s t o a centra l location . Th e final reaso n mos t metal s use d in catalyst s ar e no t recycle d is eco› nomic . Meta l price s in genera l hav e no t kep t pac e wit h oil an d genera l inflatio n pric e increases . N e w relativel y low-volum e processin g plant s can › no t compet e wit h larg e existin g meta l refinin g facilitie s unde r curren t marke t conditions . Factor s suc h a s stabilit y of supply , dependenc e on othe r countries , balanc e of payments , an d strategi c metal s considerations , shoul d increas e metal s recyclin g in th e future .

VIL

Effect s of Catalysi s on Life-Styl e A.

PLASTIC S

On e of th e larges t change s in ou r lives thi s centur y ha s bee n th e introduc › tio n of large-volum e plastic s int o th e consume r market . Th e productio n of

1

Industrial Catalysis

21

mos t polymer s involve s catalyst s eithe r in th e polymerizatio n itsel f or in th e monome r synthesis . Som e of th e larges t volum e plastic s (Tabl e VI ) an d th e type s of catalyst s (Tabl e VII ) employe d in thei r synthesi s ar e given a s examples . In th e cas e of polyethylen e an d polypropylen e ther e ar e hundred s of Ziegler-Natt a catalys t modification s in th e paten t literature .

B.

TRANSPORTATIO N

Moder n societ y is highl y mobil e an d depend s on th e rapi d transi t of peopl e an d commodities . Transportatio n vehicle s incorporat e man y of th e plastic s describe d in th e previou s section . Thes e material s hav e bee n substi › tute d for meta l t o reduc e weigh t an d cost . Anothe r majo r chang e ha s occurre d in tires . Catalyst s hav e allowe d th e preparatio n of syntheti c rubbe r an d fibers tha t ad d strengt h t o tires . Bette r fuels for th e transportatio n industr y hav e bee n mad e availabl e throug h refiner y catalys t developments . Som e refiner y processe s ar e de › scribe d in detai l in subsequen t chapters . Withou t catalyst s t o conver t crud e oil int o high-octan e fuels efficiently , ou r transportatio n syste m woul d b e severel y limite d an d ou r life-style significantl y impacted .

C.

DETERGENT S

C o m m o n househol d detergent s tha t ar e biodegradabl e an d effectively clea n ou r clothin g an d dishe s ar e a n exampl e of th e subtl e involvemen t of catalysi s in ou r life-style. Th e first syntheti c detergent s wer e produce d in German y durin g Worl d Wa r I whe n anima l fat s wer e no t availabl e for soa p manufacture . A wid e variet y of surfactant s ar e no w produced . Ou r focu s is on th e catalyst s use d t o prepar e th e buildin g block s for surfactant s an d th e actua l synthesi s of th e activ e ingredients . Onl y large-volum e surfactant s ar e describe d in Figs. 6 - 8 . Alky l sulfonate s an d olefin sulfonate s ar e mad e wit h sulfu r trioxide , whic h provide s adequat e aci d catalysis .

D.

F O O D SUPPL Y

Catalysi s ha s playe d a n importan t rol e in increasin g cro p yield s t o mee t th e food demand s of a n increasin g worl d population . Fertilizers , pesticides , an d herbicide s hav e bee n use d t o increas e yield s of agricultura l commodi › ties. Chemical s hav e mad e it possibl e t o gro w mor e on less lan d wit h less inpu t of labo r an d energy .

TABLE VI Some Importan t Industria l Polymer s Name of polymer Polyethylene

Monomer CH *CH

2

Polymer ...Ch^-Ch^.

2

H

I Polypropylene

CH^-CH^CH^

. . . C-CH^ • • • CH

3

CI

21

Polyvinyl chloride (PVC)

CH^CHCl

I . . . C H - C H 2. .

Polytetrafluoroethylene Teflon, Halcon, Fluon, Hostaflon, Algoflon, Polyflon, Soreflon, Fluoroplast

CF =CH

. . . C F 2- C F 2.

Polyacrylonitrile

CH^CHCN

CN . . .CH-CH ..

2

D rn Creslan, a l Orion, o Zefran, Acrilan, 0

H0-C=0

C HI

II Polyacrylic acid

CH^CH-COH

.••

2- ^ " • • H

| Polymethylmethacrylate

3 „

CH^-C—C-0CH

| 3

3

••-C-CH^.. C-OCH, Jl 0

3

Polystyrene

2

16 5 H

fe5

CH =C

I H

Polyisoprene

.C-CH 2 3 CH, H I .CH C = C H - C H . 2 20

2

.CH -CH=CH-CH ... 20 20

I =C-CH=CH

CH 2

Polybutadiene Cis-4, Budene, Diene, Cisdene, Ameripol CB

3 2

CH =CH-CH=CH

2

H

0

21

Polyformaldehye Ultraform, Celcon, Delrin, Hostaform, Tenoc, Duracon, Kenmetal

I

II

.C-0...

HCH

I H

Mr Poly-l-butene

|2 CH^CH

CH

|2

5

2

3

J

Polyphenylene oxide PPO, Noryl Polyamide

Nylon For example, Nylon 66

3

CH

HOOC(CH ) COOH + H N ( C H ) N H adipi c acid

5

.CH -CH.

24

2

26

2

hexamethylen e diamin e

3

.C(CH ) C-«(CH ) -N.

24

26

Table VI (continues)

TABL E VI Name of polymer Poly(ethylene terephthalate) (Dacron)

(Continued)

Monomer

Polymer

CH OOC(C H )COOCH + HOCH CH OH

3

64

3

4^

2 2

. C - ( ( L H , )-C0CH CH 0. tl 6 4 ' I. 2o 2o 0 I CH

Polycarbonate Lexan, Merlon, Makrolon, Makrofol, Panlite, Jupilon, Touflon

Bisphenol A + phosgene

0-CH 3

CH | CH

0

3

0 ||

TABL E VII Catalys t Type s in Polyme r Synthesi s Polymer

Major uses

Catalyst type

Polytetrafluoroethylene (Teflon) Polyacrylonitrile

Film and sheet, injection molding, blow molding Film and sheet, injection molding, blow molding Molding and extrusion, sheeting, flooring, wire coating, adhesives and paints, film, furnature, clothing Fluid handling, packings, electrical wire coating, pipe and hose, nonstick surfaces Fibers, fabrics, elastomers, plastics

Chromia (Phillips), titanium trichloride (Ziegler-Natta) Titanium (Ziegler-Natta) (isotactic) Peroxide initiator; monomer preparation requires C u C l 2 KC1-A1 0 oxychlorination catalyst 23 Na, K, N H peroxydisulfate polymerization agent

Polyacrylics

Copolymer with butadiene, fibers, plastics

Polymethylmethacry­ late

Plastics, sheets, paints, textiles

Polyethylene Polypropylene Polyvinyl chloride

4

Monomer preparation: CH + io 2 36 C H = C H C N + 3 H 0 , bismuth phosphomolybdate 2 2 catalyst Monomer synthesis by oxidation of propylene, B i 0 / 3 M o 0 ; C H = C H + 2CO + 0 , PdCl /CuCl 3 2 2 2 2 2 Monomer prepared using acetone, methanol, and hydro­ gen cyanide

C

2H2

-

+ CO

CH + NH ^

4

Polystyrene

Insulation, packaging, injection molding, extrusion, meat trays, film

Polyisoprene

Synthetic rubber blending with natural rubber or cis-1,4polybutadiene Rubber, especially copolymer with styrene (SBR) and acrylonitrile (NBR)

Polybutadiene

3

ru

Qo

3 ,

HCN + 3H

HC

r

Z

n

H

2

Free radical initiation polymerization Isotactic polystyrene made with Ziegler-Natta catalyst. Monomer made by dehydrogenation of ethyl benzene over F e 0 - K O H - C r 0 23 23 £-TiCl , Ziegler-Natta, or alkyllithium

3

Ziegler-Natta catalyst for polymerization. Dehydrogena­ tion of butane or butene Table VII (continues)

3

0

TABLE VII Polymer

(Continued)

Major uses

Catalyst type

Polyformaldehyde

Engineering plastic

Poly-l-butene Polyphenylene oxide

Pipe, film Engineering plastics Injection molding, pipe and rod, film, sheet, slab

Nylon Poly(ethylene terephthalate) (Dacron)

Fiber, fabric, carpets, yarns Fiber, fabric, carpets, yarns

t ca oce be at la t

Adipic acid synthesis: Cyclohexane + 5 0

BF catalyst used in polymerization. Monomer made by 3 air oxidation of methanol over F e ( M o 0 ) or silver 43 gauze + 2+ Ziegler-Natta catalyst (isotactic) Cu , amine polymerization catalyst—also M n Magnesium oxide catalyst to prepare 2,6-xylenol from methanol and phenol Melt spinning Antimony catalyst (many others also possible), dimethylterephthalate

> 2 adipic acid + 2 H 0

2

2

Terephthalic acid synthesis: o 2 p-Xylene terephthalic acid Br catalys t

2

Ethylene glycol synthesis: CH =CH

2

102

2

Ag

• C H — C H + HX> —

2

2CH =CH + 2H 0 + 0

2

Polycarbonates

2

2

2

2

HOCH CH OH

2 2

TeQ promote d by Br compound s or manganes e acetat e + potassiu m iodid e catalys t

2

Engineering thermoplastics, extrusion, film, blow molding

• HOCH CH OH

2 2

A1C1 polymerization catalyst

3

27

1 Industrial Catalysis

n-Paraffin

CL

Alkylbenzene

Alkyl Chloride Benzene

b 1

Olefin *i

d

Olefin Metathesis

Fig. 6. Linear alkylbenzene sulfonates, a, A1C1 catalyst; b, Pt/A10 catalyst; b, P t / A l 0 3 3 23 catalyst; c, H F catalyst; d, C o O - M o 0 - A l 0 ; e, aluminum alkyls with heat- or nickel-cata­ 3 23 lyzed alkyl displacement.

Abou t 80% of th e ammoni a produce d worldwid e is use d as fertilizer . A m m o n i a is forme d fro m th e catalyti c reactio n of nitroge n fro m air an d hydroge n fro m natura l gas. Th e synthesi s of herbicide s an d pesticide s als o involve s catalysts . Th e market s ar e highl y fragmented , bu t th e agrichemical s researc h are a is on e of hig h activity .

Ethoxylated Alcohol

2 ?

CO, H Olefin

b

**

Alcohol

Fats and Oils

Fig. 7. Alcohol-derived surfactants, a, Trialkyl aluminum; b, cobalt or rhodium oxo catalyst; c, copper chromite catalyst; d, NaOH, Ba(OH) , or Sr(OH) .

2

2

28

Bruce E. Leach

Olefin

3 v

Alkyl Phenol

Ethylene Oxide

b

*

Alkyl Phenol Ethoxylates

Phenol Alkyl Phenol SulfatesSulfonates

Fig. 8. Alkyl Phenol Derived Surfactants, a, HF or strongly acidic ion-exchange resin; b, NaOH catalyst.

E.

ENERG Y CONVERSIO N A N D CONSERVATIO N O F RESOURCE S

In th e futur e we ma y b e faced mor e wit h a shortag e of energ y in a particula r for m tha n wit h a tota l shortag e of energ y sources . Catalyst s will pla y a n increasingl y importan t rol e in th e synthesi s of chemical s an d fuels fro m coal , shal e oil, an d ta r sands . Conversio n of energ y fro m on e hydrocarbo n for m t o anothe r basicall y involve s hydrogenation-dehydrogenatio n reactions . Coa l an d shal e oil ar e deficien t in hydroge n an d ar e liquefie d b y catalyti c hydrogenation . Alternativel y th e conversio n ca n b e accomplishe d b y gasificatio n t o H 2 an d C O followed b y a synthesi s reactio n t o alcohol s or hydrocarbon s afte r a n appropriat e wate r gas shift reactio n [Eq . (2)] t o for m th e require d amoun t of hydrogen .

W

Catalyst CO + H 0

2

^

C0 + H

2

2

(2)

Energ y conservatio n will becom e mor e important . Improve d catalyst s for commercia l processe s hav e th e potentia l for reducin g operationa l pressure s an d temperatures , thereb y savin g energy . E.

E N V I R O N M E N T A L EFFECT S O F CATALYST S

Catalyst s hav e foun d extensiv e us e in pollutio n control . Th e catalyst s use d t o reduc e automotiv e emission s hav e helpe d contro l th e hydrocarbons , carbo n monoxide , an d nitroge n oxid e levels in th e atmosphere . Th e sam e

1

Industrial Catalysis

29

typ e of preciou s metal-base d catalyst s ar e als o usefu l in reducin g hydrocar › bo n emission s fro m ven t stream s in chemica l operations . Whil e catalyst s ca n hel p clea n u p th e environment , at th e sam e tim e the y ca n themselve s pos e environmenta l problems . Solid wast e disposa l is a majo r proble m in th e 1980s. It ha s receive d publicit y becaus e of mistake s mad e in th e handlin g of hazardou s waste s in th e past . Th e questio n of wha t constitute s safe disposa l is still bein g debated . N e w regulation s coverin g shipping , packin g an d storin g waste s hav e alread y bee n set in th e Unite d States , wit h stiff legal penaltie s for failur e t o comply . Th e disposa l cost s an d th e recycl e valu e of meta l catalys t component s combin e t o give catalys t regeneratio n a promisin g future . Catalyst s contain › in g mor e toxi c heav y metal s tha t ma y b e extracte d int o groundwate r (e.g., chromium ) will stimulat e researc h for alternativ e catalys t system s tha t d o no t requir e expensiv e or hazardou s wast e disposal . Catalys t preparatio n itsel f ofte n involve s aqueou s salt solution s fro m precipitatio n reaction s an d meta l ion-containin g wast e streams . Io n ex› chang e ha s bee n ver y helpfu l in solvin g meta l contaminatio n problems . In calcination , th e decompositio n of nitrates , sulfates , chlorides , etc. , produce s vapor s tha t mus t b e scrubbe d t o ensur e air qualit y control . Th e acidi c aqueou s solution s ar e neutralize d an d th e salt s concentrate d in holdin g ponds . Ion-exchang e resin s hav e bee n develope d t o reduc e preciou s metal s 4 +an d 3Haa + s C o m3›+ selectively . Amboran e reductiv e resin s prepare3d +b y 2R+ oh m pan y ca n reduc e preciou s metal s suc h a s A u , P t , P t , R h , an d I r , retainin g th e reduce d meta l withi n th e water-insolubl e polymeri c resin . Th e metal s ca n the n b e recovere d b y slowly roastin g th e metal-containin g bead s of polymer . Th e capacit y for reduce d meta l is 1 - 2 g meta l per gra m of dr y resin . Th e stoichiometr y of th e reductio n is given in Eq . (3).

n

n - (P) - B H + 6 M

3

Amborane Resin

Metal Ion

(g) - H

+ 6 M° + 5n H

Resin Loaded With Reduced M e t a l

+ nB(OH)

3

(3)

Boric Acid

Method s of meta l recover y will continu e t o b e develope d given th e emphasi s on wate r qualit y an d th e impac t of metal s cost an d availability .

Reference s 1. E. J. Rosinski, T. R. Stein, and R. H. Fischer, U.S. Patent 4,082,695 (1978). 2. R. D. Christman, G. E. Elliott, and G. Guelfi, U.S. Patent 3,730,879 (1973). 3. P. Sabatier, "Catalysis in Organic Chemistry." Van Nostrand, New York (1922).

30

Bruce E. Leach

4. A. Mittasch, In "Advances in Catalysis" (Vol. 2), pp. 81 - 1 0 3 . Academic Press, New York (1950). 5. B. Luberoff, Chem Tech. page 8, (1981). 6. K. Ziegler, Brennst. Chem., 35, 321 (1954); Belgian Patent 527,736 (1954). 7. J. Boor, Jr. "Ziegler-Natta catalysts and polymerizations," pp. 93-100. Academic Press, New York (1979). 8. H. Coover Jr., F. Joyner, and N. Shearer Jr., Belgian Patent 577,216; also see U.S. Patent 3,549,608, issued to H. W. Coover and F. B. Joyner (1970). 9. J. Stevens, and M. George, (1976). Belgian Patent 757,847; Solvay & Cie (1976). 10. K. Tsubaki, H. Morinaga, Y. Matsuo, and T. Iwabuchu, UK Patent Application GB2,020,672A(1979). 11. B. Leach, J. Org. Chem. 43, 1794 (1978). 12. R. Arganer, and G. Landolt, U.S. Patent 3,702,886 (1972).