CA1077525A

CA1077525A - Hydrocarbon synthesis from co and h2 with ru, ni or rh supported on titanium oxide

Info

Publication number: CA1077525A
Application number: CA275,338A
Authority: CA
Inventors: Robert L. Garten; M. Albert Vannice
Original assignee: Exxon Research and Engineering Co
Current assignee: ExxonMobil Technology and Engineering Co
Priority date: 1976-04-05
Filing date: 1977-04-01
Publication date: 1980-05-13
Also published as: FR2347326B1; JPS52122307A; FR2347326A1; DE2712909A1

Abstract

ABSTRACT OF THE DISCLOSURE

An improved process for the synthesis of hydrocarbons comprising passing H2 and CO over a catalyst at a temperature, pressure and for a time sufficient to generate the desired products wherein the improvement consist in using as a catalyst ruthenium, nickel or rhodium supported on a titanium-containing oxide.

Description

~L~775Z5 . ~

1 It was discovered by Pichler (see H. Pichler,

2 Brennstoff-Chem. 19, 226 (1938~, H. Pichler and H. Buffleb,

3 Brennstoff-Chem. 21, 247, 273, 285 (1940)) in 1938 that Ru

4 can produce at low temperstures and very high pressures, ~igh mQlecular weigh~ paraffinic wa~es. Because it is such a ~ood hydrogenation catalys~, ruthenium has no~ been n~ted 7 for its capabili~y to produce oleins. This is shown by the 8 only study conducted under typical synthesis conditions us-9 ing supported Ru where at 2160 kPa, 220-240~. and H2/CO
rati~s of 1 to 3, it was no~ed that ~he hydrocarbon product 11 contained only "moderate" amounts of olefins (see F.S. Karn 12 et al~ I~EC Product Res. & Devel. 4, 265 (1965)). At a 13 H2/C0 ratio of 1, over 85 wt. % of the hydrocarbon product 14 was composed of C5+ material. In addition, at 100 kPa and 22~C., m~thane was the only hydrocarbon product observed.
16 It is clear then t~a~ typical Ru catalysts would be expe~ted 17 to produce primarily high molecular weight paraffins at 18 moderate pr~ssures and methane as ~he principal product at 19 atmospheric pressure.
Because it i3 SO e~pensive, only supported, highly 21 dispersed ~u c~talysts can be considered for ~y co~mercial 22 synthesis process since only in this state can the catalytic 23 activity of most, if not all, of the Ru atoms be utilized.
24 It is necessary then to prepare ~hese ~a~alysts in such a way tha~ they posse~s a large Ru surface area thereby reduc-26 ing the weight loading of Ru required to achieve the desired 27 activity. ~n e it is now possible ~o produce ca~alys~s in 28 ~his manner, ~key may now be seriously cvnsidered as can-. ., ~; 29 dida~es for the commercial synthesis of olefins and paraffins rom C0 and H2.
' ~

''~` ' 7 7 ~ 2 5 l A new method for the selective synthesls of ole-2 finic hydrocarbons and particularly olefins of from C2 to 3 Clo chain Leng~h inclusive from CO an,d H2 at pressures o from 100 to 3100 kPa comprises the stleps of passing a syn thesis gas stream comprising CO and H2 at a H2/CO ratio of 6 from Ool~10~ preferably 0.5-43 most preferably 1-3, at a 7 space velocity o from 100 hr~l to 50,0~0 hr~l over a ca~a-8 lyst comprising from 0.01 to 15 wt. % ruthenium on TiO2, 9 other titanium-containing oxides or mixtures thereof for a time sufficient to effect the generation of desireld oleflnic ll hydrocarbon products at a temperature of from 100 to 500C., 12 preferably 150-400C., most preferably 150-300C., and a 13 pressure of from lOO ~o 105 kPa ~l-1000 atm.~, preferably 14 100-3100 kPa, most preferably, 100-2060 kPa. The supported ruthenium catalyst system used in the instant process has 16 a total B~T surface area o~ from 10 to 60 m2g~l with a l7 ruthenium crystallite size of preferably less than 5nm l8 (50 A)~
19 '! ~uthenium supported on TiO2, other titanium-con-taining oxides ~r mixtures of titanium oxides, comprises a 21 catalyst system which exhibits superior hydrocarbon syn-22 thesis characteristics in syn~hesis processes. The titanium-23 containin~ o~ide supports which may be used in the prac~ice 24 of this invention are oxides havi~g surface area~ of from 25 1 to 200 m2g 1~ preferably 10-100 m2g~l, most preferably, r 26 25-100 m2g~l. The oxides are selec~ed from the group com-27 prising TiO2, Al203-TiO2, ~iO2-TiO2~ TiO2 Carbo~ 4, 28 alkaline earth titanates (BaTiO3, CaTiO3, SiT103, MgTiO3) 29 alkali titanates ~Na2TiO3, Li2TiO3, K2TiO3) and rare earth titanates, preferably, the ti~anium oxide TiO2. With mos~

~;' ' .

1~75~5 l supported metal catalysts, the higher the surface area of 2 the suppor~, the higher the disperslon o~ ~he supported 3 me~aL at a given metal loading. I~ is therefore desirable 4 to use a TiO2 with as high a surface area as possible to maximize the dispersion of the ruthenium metal. However, 6 when working with TiO2, samples with surface areas of 150 7 to ~50 m2g~l (usually prepared by precipitation techniques) 8 desurface on heating to ~ 500C. Commercially available 9 TiO2 made by flame hydrolysis o~ TiCl4 has a stable sur-0 face area of ~ 60 m2g~~ for ~hermal treatments at tempera-ll tures o -~- 500C. and is there~ore the preferred suppor~.
2 For thermal ~reatments at temperatures below 500C., TiO2 l3 prepared by precipitation ~echniques may be successfully 14 employed. Ruthenium is deposited on the chosen suppor~ in a concentration of from 0.01 to 15 wt. %, preferably 0.1 to 16 10 wt. %, most preferably 0.5 to 5 wt. %, with the ruthenium l7 possessing a crystallite size, as determined by standard l8 techniques such as X-ray diffraction or transmission elec- :
l9 tron microscopy of from l to 20 nm, preferably 1-10 nm, most preferably 1-5 nm.
21 Using standard experimen~al techniques, for a 22 ruthenium on TiO2 system, reduced in hyclrogen at 450C., X-23 ray diffraction shows no particles of Ru in the reduced cata-24 lyst which indicates particles having crystallite sizes of less than 5 nm) which corresponds to a dispersion of ~reater 26 than 20%~
27 Ru~henium catalysts supported on TiO2, other tita-28 nium-con~aining oxides, or mixtures thereof, exhibit selec-29 tivity to olein produets, especially C2-Clo inclusive ole-fins. Such catalysts, when used in ~he present system, ex-`' ~ 4 ~ ~ :

~775~5 1 hibit improved selectivity to said olefins, improved longev-2 ity and tolerance to sul~ur and resistance to ruthenium 3 volatilization in oxidizing atmospheres as compared with 4 ruthenium catalys~s of the prior art which are suppor~ed on materials such as A1203, SiO2 or carbon.
6 The ruthenium catalysts employed in the practice 7 of the present process are themselves prepared by techniques 8 known in the art for the preparation o other ca~alyst sys-g tems, such as Ru on A1203, etc. A suitable ruthenium salt 0 such as ruthenium chloride, ru~henium nitra~e or ruthenium 11 acetate, etc., is dissolved in a solvent such as water or 12 any suitable solvent and stirred with the chosen titanium 13 oxide system. Preferably, the.suppor~ is TiO2 prepared by 14 ~lame hydrolysis o~ TiC14, which TiO2 has a sur~ace area of ~J60 m2g~l. After thorough mixing ~he mixture is allowed 16 to dry and then heat treated in air at a temperature of from 17 100 to 150C. or alternatively may be dried immediately by 18 heating in air at a temperature of between lQ0 to 150Co 9 for several hours.
However, there is a final step, which is essential, 21 of heat treating the supported ruthenium catalyst, prepared 22 as outlined above, or by similar techniques, in a reducing 23 atmosphere such as hydrogen at a temperature greater ~han 24 300Co~ preferably greater than 400C., most preferably, greater than 500C~, for from .5 to 4 hours, preferably 1-2 .
26 hours.
: 27 Nickel suppor~ed on TiO2, other ti~anium-contain-28 ing o~ides or mix~ures of various titanium oxides as des-29 cribed above comprises a catalyst system which eghibits superior hydrocarbon synthesis charaoteristics. Such sup-;~

~137752S

1 ported nickel catalysts exhibit selectivi~y to paraffinic 2 hydrocarbon products o from C2 ~o C7 which are free of ole-3 ins and oxygenated products, They generate C0 conversions 4 of up ~o 60% at pressures of 3090 kPa without signiflcan~
change in product distribution. A large frac~ion of the 6 product obtained contalns 2 or more carbon atoms in the 7 chain up to conversions o 60%. The supported nickel cata 8 lysts exhibit enhanced activity, improved selectivity to :~
9 higher molecular weight normal paraffins, improved longevity and tolerance to sulfur and resistance to nickel carbonyl 11 formation as compared to nickel catalysts on o~her supports 12 such as Al203, silica or carbon:
13 Conventional nickel catalysts, iOe. Ni/.Al203, 14 N~/SiO2 etcO are well known for their selectivity toward me~hane formation~ for example see M. Greyson, "Catalysis", 16 VolO IV, 473 (1956) and H. Ao Dirksen and Ho Ro Linden, 17 Research Bulletin #31, Institute of Gas Technology (l963~.
8 Wi~hin a wide range of temperature, pressure and H2/C~ .
19 ratios, methane is by far the predominant hydrocarbon pro-duct and it is this fact ~hat has made nickel the catalyst 21 of choice for commercial methane synthesis rom C0 and H2-22 ~iokel has been dispersed on and co-precipi~ated 23 wi~h a wide variety of typical oxide supports and no major 24 effect on prod~ct distribution has been noted. When higher hydrocarbons have been observed, they are stiLl usually 26 gaseous ma~erials consisting primarily of e~hane a~d only 27 small quan~ities of C3+ hydrocarbons~ The effect of a large 28 number of promoters on the activity and selecti~i ty of nickel 29 catalysts has been studied and ThO2 is the only material to have a pronounce~ influPnce on the product distributionO

1~77525 1 Usually used with Ni/Kieselguhr catalysts, the addltion of 2 12-24 parts ThO2 per 100 parts Ni results in up to 60-70 wt.
3 % of the total hydrocarbon product pre~en~ as CS~ material 4 including solids and liquids (see R.B. Anderson, "Catalysis", Vol. IV, p. 53 (1956)). No other promoters have been docu-6 mented as being capable of inducing th:is change in product 7 selectivity. Al~hough catalys~ activi~y was increased ~ome-8 wha~ by the addition of ThO2, the increases were not large, 9 normally consisti~g o lncreases up to 10% in the H2 + CO
10 conversionO
Therefore, nickel oatalysts have been used fre-12 quently in the past to synthesize methane from CO and H29 13 and are quite selective in producing this product~ With the 14 exception of catalysts promoted with ThO2, ~hey were not known to possess ~he capability of producing large quantities 16 of higher molecular weigh~ products. This invention dis- -l7 closes ~he modification of the ca*.alytic behavior of nickel l8 by dispersing i~ upon TiO2 or a Ti~containing support re-19 sulting in a catalyst which is employed in a process which yields a much higher average molecular weight productO The 21 highly desirable effect of greatly increasing the activity 22 of the nickel component is also obtainedO
23 A n~w method or ~he selective synthesis of higher 24 molecular weight normal paraffins from CO and H2 over a wide range of CO conversions at pressures of from 103 to 3090 26 kPa comprises ~he steps of passing a s~nthesis gas stream 27 comprising CO and H2 at a H2/~0 ratio of from Ool10~ pre-28 ferably 0O5-4~ most preferably 1~3 at a space velocity of 29 from 100 hrO-l to 50,000 hrO~l over a catalyst comprising from OoOl to 75 wt. % Ni on TlO2, other titanium eontaining 1 oxides or mix~ures o said ~.itanium-ccntaining oxides for a 2 time suficient to effect the generation o desired p~raffin-3 ic products at a temperature of from 1.00 to 500Co~ prefer-4 ably 150~400C.3 most preferably 150-300C. and a pressure of from 103-1.03 ~ 105 kPa9 preferabl~ 103~3090 kPa, most 6 prefera~ly 103-2060 kPa. The supported nickel catalysts 7 system has a ~otal BET surface area of from 10 to 60 m2g 1 8 of total catalyst with a nickel crys~allite size of prefer-9 ably less than 10 nm (100 A) ~as measured by X~ray diffrac-tion). A suitable size range is 1 30 nm~ preerably 1-10 1 nm, most preferably 1~705 nm, 2 Using gtan~ard experimental techniques, 10% Ni 13 TiO2 reduced in hydrogen at 450Co (as in the following 14 e~amples) evalusted by X-ray diffraction e~hibited a crys-tallite size of 7.5 nm which corresponds to a nickel dis-6 persion of about 14a/oo For a 105% Ni/TiO2 system~ the . .
-i 17 particle size is less t~an 5 nm since ~i metal was not de-. ...................................................................... .
18 tectable by x-rayO This corresponds to a dispersion of 19 greater than 20%o The nickel catalysts employed ln the prac~ice of 21 the present process are themselves prepared by techniques 22 slmilar to tho~e described above for rutheniumO
23 A supported Ni/TiO2 catalyst can also be prepared 24 by reduction o~ ~he compound NiTiO3 whlch on reduction in hydrogen at ~empera~ures o abou~ 450Co decomposes into .. .
-~ 26 nlckel metal supported on TiO2- Reduction of ~he stoiehio-27 metric NiTiO3 to Ni/TiO2 gives a catalyst o composition 38 28 wto % ~i/TiO2, 29 The ~inal s~ep of heat treating is as Idescribed ; ~ above for the suppor~ed ruthenium catalyst.

~77S2~

1 The present process will selec~ively generate C
2 normal paraffins from CO and H2 in coDjunction with the 3 above-de3cribed nickel catalyst sys~ems provided operation :~
4 ls ~.onducted at a ~emperature below 5C10C. Use of the ca~alys~ also allows synthesis ~o be run at temperatures 6 lower than those disclosed in ~he prior ar~ with equivalent 7 produc~ yields and CO conversion ra~es and such superior 8 results are obtai~ed when using catalysts possesslng Ni 9 weight loadings e~ual to those of the prior ar~O
Rhodium catalysts for the production of higher 11 molecular weight hydrocarbons from CO and H2 have been re-12 ported only in a Bureau of Mines S~udy (J. Fo S~ul~z et 13 alO, UOSO Bureau of Mines Report ~6974~ 1967)o This study 14 showed that rhodium supported on Al2O3 produced 95~ w~O %
me~hane a~ typical H2/CO ratlos, 2163 kPa pressure and at 16 temperatures from 440-580Co Because o its e~pense and low 17 activity compared ~o other metals, rhodium wa3 reported by ~ these workers to be unattractive as a methanation c~talyst.
19 It has now been found, however, that rhodium dis- -,~
persed on TiO2 or other titanium-containing oxide supports 21 as described above has high activity and altered selectivity.
.
22 Compared to A1203-suppor~ed rhodium, the use of TiO2 or ti-~3 tanium-containing oxide-supportPd me~al in olefin prepara-24 tion proeesses resul~s in a process which exhlbits a marked ~' 25 decrease in methane in the produc~s wlth a concomi~ant ln-:`
26 crea~e in the formation of higher molecular weight paraf~ins 27 and olefins.
28 A new method or ~he improved syn~hesis o~ olefin-: 29 ic hydrocarbons and particularly olefins o~ ~rom C2 to Cs chain length ~nclusive, and most particularly, C3 and C4 _ g _ ~775Z5 1 hydrocarbons from C0 and H2, comprises the steps of passing 2 a syn~hesis gas s~ream comprising C0 and H2 at a H2/CO ra~io 3 of from 0.1-10, preferably 0OS~4, most preferably 1-3 at a 4 space velocity of from 100 hr~l to 50,000 hr 1 over a cata-lyst comprising from 0,01 to 10 wt~ Z rhodium on Ti02, other 6 t~tanium-containing oxides or mix~ures thereof for a time 7 sufficient to efect the generation of desired olef:inic hy-8 drocarbon pro~ucts in ~he desired ratio, said contacting 9 being effected at a temperature of from 100 to 500CO, pre-lo ferably 150 400C., most preferably 150-300Co and a pres-11 sure of ~rom 100 to 105 kPa, preferably 100 to 3000 kPa, 12 most preferably 100-2000 kPa. The supported rhodium catalyst 13 system used in the instant process has a total BET surface 4 area of rom 10 to 60 m2g 1 with a rhodium crystallite size of preferably less than 5 nmO
16 Rhodium is deposited on the chosen suppor~ in a 7 concentration of from OoOl to 10 wt, %, preferably 0O05-S
18 wt. %, most preferably 0Ol-2 wto %~ with the rhodium possess-9 ing a crys~all~te size, as determined by standard techniques 20 such as X-ray diffraction or transmission electron micro- :~
21 scopy of rom 1 to 20 nma preferably 1-10 nm, most preferably 22 1-5 nm.
23 Using standard experimental techniques, for a rho-24 dium on Ti02 system reduced in hydrogen at 450C., X-ray ;:
i.~.l .
diffraction shows no particles of rhodium in the reduced 26 catalys~ which indicates ~hat the rhodium crystallites pos-27 sess an average size of less than 5 nm, w~i~h corresponds 28 to a dispersion of greater ~han 20%.
29 The rhodium catalysts employed in the practice of the instant process are ~hemselves prepared by techniques ~75Z~ ::
;::
1 similar to those described above for rutheniumJ
2 The final step of heat treat:ing is as described 3 above ~or the supported ruthenium ca~alyst.
Use o the above-identiied catalyst in the pres-ent process at reaction conditions eqtlivalent to ~hose o~
6 ~he~prior art gives superior results ~(in the way of improved 7 selectivity and greater product yields~ when catalysts 8 possessing rhodium with loadings equal to those ~f the 9 prior art are usedO ~
10 ~_~ "
11 Ruthenium catalysts with improved selectlvity to 12 olefin products and to hydrocarbons with carbon chain lengths 13 of two carbons to ten carbons are obtained by deposi~ing ,.1 , .
14 ruthenium on TiO2 or titanium-conta~ning oxlde supports.

5 Thus, a 2% Ru/TiO2 cstalyst i~ prepared by stirring ~oge~her

6 10 grams of ~iO2 and 3 ml of ~uC13 solution containing 0.2 g

7 of ruthenium. The TiO2 is prep~red by the flame hydrolysls

8 of TiC14 to give a support with 60 m2g~1 surface area. Ti-tania made by other ~echniques such as precipLtation and 20 calcination o~ a suitable salt is also satisfactory. Af~er 21 thoroughly mixing the TiO2 and the ruthenium solution, the 22 mixture is dried overnight in air at 110-120C.
23 To illustrate the desirable propertles of Ru/TiO2 24 cataiysts, they were compa~ed to ruthenium supported on con-25 ventional supports such as A12O3 or carbonO Thus, a 5%
26 Ru¦ ~ -A1203 c~t~lyst was prepared by thoroughly mixing 5.26 27 ml of RuC13 solutibn con~aining 0.526 grams of ruthenium ~8 with 10 grams of ~ -A1203. The resulting mixture was dried 29 overnight in air at 110-120C. A 4% ~u/carbon catalyst was 30 prepared by ~horoughly mixing 6 ml o~ RuC13 ~olutton con-':

~775Z5 1 taining 0.12 grams o~ ruthenium with 3 grams of carbon with 2 a surface area o ~ 1000 m2g~l. The resul~ant ~ixture was 3 dried overni~ht in air at 110-120~C.
4 The desirable selectivity characteristics of TiO2 or titanium-containing oxide-supported ruthenium catalysts 6 compared to other supports are demonstrated ln Tables I, II
7 and IIlo A~ 103 kPa total pressure Ru/TiO2 shows a markedly 8 di~ferent product distribution from Ru/A1203, The formation

9 of methane and very high molecular weigh~ hydrocarbons is lo suppressed over the Ru/TiO2 catalysts giving a product spec-11 trum i~ which the carbon chain length range of two to five 12 carbon atoms is maximi~edO For Ru/A1203, much more me~hane 13 and higher molecular weight hydrocarbons are produced.
14 Ru/TiO2 also po~sesses the desirable characteristics that a 15 large ~raction of the C2-Cs products is olefinic~ Thus, :
this catalyst is particularly suitable for producing from 7 CO and H2 a product stream which is highl~ olefinic and with : :
8 carbon chain lengths of two ~o five carbon atoms~ Olefins -9 such as ethylene, propylene) butenes and pentenes in this range are particularly desirable as che~ical intermediates 21 for ~he production of plastics, rubber~ alcohols, ketones 22 and aldehydes, esters and acidsO ~ .:
23 Table II illustrates the desirable selectivlty -~
24 characterls~ics of TiO2 or titanium-containing oxide-sup-2s poxted ruthenium ca~alys~s at higher total pressures of 26 reactants, At 103 kPa ~he RulTiO~ makes less methane and 27 C8~ hydrocarbons than Ru/A1203 with most of the produc~s 28 from Ru/TiO2 being in the C2 to C7 carbon number range, 29 Ru/TiO~ thus exhibits i~proved selectivity to the desirable C~ to C7 hydrocarbons. Table II also illu~trates ~he im-- 12 ~

, .

1~1775Z5 1 proved selectivity to olefins of Ru/TiO2 compared to ~u/
2 Al203. In the C2 to C5 carbon number range 42% of the pro-3 ducts are olefins with Ru/TiO2 whereas only 25% are olefins 4 with Ru/Al~03. Ru/TiO2 is thus more selective for ~he pro-duction o the`desirable olefins with carbon chain lengths 6 of two to five carbon atoms~
7 Table III compares Ru/TiO2 with ruthenium on a 8 varie~y of other supports. Ruthenium supported on TiO2 or 9 titanium-containing oxlde supports produces 42 wt. % of the products wlth carbon chain lengths of two to five carbon 11 atoms, while ru~henium on A1203, carbon or ruthenium metal 12 produce only 31%, 2% and 25%, respec~ively of products in 13 this c~rbon number range. In addition, the fraction of 14 olefins in the products is greates~ for Ru/TiO2 as indicated by the ethylene/ethane ra~ios for each catalyst. Ruthenium 16 on Al203 or carbon, or un~upported ruthenium metal produce 7 little or no ethylene -Ln the C2 fraction from C0 and H2 18 under the reaction conditions used in Table III whereas 19 Ru/TiO2 produces about one-half of the C2 fraction as ethylene~

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~ .'''' ~1377S~5 1 E _MPLE 2 2 Catalysts with improved activity and selectivi~y 3 to normal para~fin produc~s with carbon chain lengths of 4 two and higher are obtained by depositing nickel on TiO~
and ot~er titanium-containing oxlde suppor~s. Thus, a 1.5%
Ni/TiO2 catalys~ is prepared by stirr;ng 11.4 ml of nickel 7 nitrate solution containing 0.39 g of nickel wi~h 25 g of 8 TiO2 in a beaker. The TiO2 was prepared by flame hydrolysis `! 9 of TiC14 and had a surface area of 60 m2g~l- Titania made by i lO other techniques such as precipitation and calcination of a ll suitable titanium salt is also satisfac~ory. After thorough-12 ly mixing the nickel solution with ~he TiO2 the resuLting 13 material is dried in ~ dessicator overnight and further 14 dried in air ln an oven at 120C. overnight. Alterna~ively the resulting material ean be dried immediately at L20C.
16 in alr for several hours. A 10% Ni/TiO2 catal~st is pre-17 pared by mixing with a spatula in a beaker 20 g of TiO2 wi~h 18 11.1 g NiNo3.6 H~O dissolved in 5 ml of distilLed water.
19 The resultant material is dried in a dessicator overnight and urther dried a~ 120C. in air overnight. By impregna~ing 21 the dried 10% Ni~TiO2 catalysts with additional quantities 22 o nickel nitra~e solution concentrations of ~i/TiO2 up to 23 ~ 75 wt. % can be ob~ained.
24 To illustrate the desirable characteristics of ~he Ni/TiO2 catalysts, they were compared to several com-26 mercial nickel cataly~ts and to several nickel catalysts 27 supported on A1203 and SiO2. Thus a 5~/0 Ni/~ -A1203 catalyst 28 was prepared by thoroughly mixing 9.5 g of ~ -A1203 having 29 a surface area of 245 m2g 1 with 6.6 ml of nickel nitrate solution contalning 0.5 g nickel. The resulting mix~ure ~3775Z5 1 was dried overnigh~ in air at 110C. A 16.7% ~i/SiO2 cata-2 lyst was prepared by ~horoughly mixing 10 g of silica having 3 a surface area o~ 300 m2g~l with 20 ml of nickel nl~rate 4 solution containing 2 g of nic~el, Thle resultlng material was dried overnight in air at 110C.
6 A series of suppor~ed nickel catalysts and bulk :
7 nickel oxide were reduced in hydrogen at 450C. for one~ hour 8 prior to the in~roduction o a CO-H2 feed at a tempera~ure 9 o 205~C. The enhanced activity o~ the TiO2-s~pported nickel catalysts relative to a variety of other nickel catalysts is 11 shown in Table IV. The 10% Ni/TiO2 catalyst is much more 12 active on a per gram of catalyst basis than other nickel 13 catalysts containing much larger quantities of nickel.

~ ~ :
, . .. . .
16 (C0-H2 Reaction Conditionso 205C, 103 kPa, H~/C0=3) 17 ~ Mole~ C0 ~Moles C0 18 Converted/Sec/ Converted/Sec/
19 5~9~ P~IoL~ 9~ C l~-t 5% Ni/ ~-A12O3 3-4~ 0.172 21 8-8% Ni/ ~ ~1203 1.63 Ø143 .
22 .42% Ni/oc-Al2o3 0.21 0.088 3 16.7% ~i/SiO2 2.36 0 39 24 20% Ni/graphite 0.064 0.082 Bulk Ni Metal 0.032 0.032 26 10% Ni/Ti0~ 22.8 2.28 27 ~.S3% Ni/TiO2 8.35 0.113 28 (a) All catalysts reduced 1 hr. a~ 450C~prior ~o activity 29 test.
TiO2 or titanium-containing oxide-supported nickel 1 catalys~s also exhibit desirable selectivity characteristics 775Z~

1 compared to bulk nickel or nickel on SiO2 or Al2O3 support~.
2 This ls demonstrated in Table V. Nickel on a variety of 3 supports, e.g. Al2O3, SiO2, graphi~e alnd bulk nickel produce 4 methane almos~ exclusively with only small amounts o~ hydro-carbons with càrbon chain leng~hs up t:o 4. The TiO2 or ti-tanium-containing oxide-supported nictcel ~atalysts show a 7 large reduction ln methane make and increase in par~ffin 8 products with carbon chain lengths of two carbon atoms and 9 higher. This is especially deslrable for the product~on o~
~torable liquld fuels from CO~H2 mixtures obtained from coal :~
1 gasification. `
12 The:increased selectivi~y of TiO2 or ~itanium-con-13 taining oxide-supported nickeL catalysts is maintained over 14 a range o conversions up to ~ SO~/O as demonstrated in Figure l. Nickel catalysts prepared from other supports, however, 16 show much poorer selectivi~y to high molecular weight para~
17 ~ins than TiO2 or titanium-con~aining oxide-supported metal 18 catalysts.
19 The selectivity of the TiO2 or tit~nium-containing oxide-supported nickel catalysts to hydrocarbons with carbon 21 chain lengths o 2 and higher is also maintained at higher 22 pressures compared to nickel on other supports. This is 23 demonstra~ed in Table VI~ The behavior of the Ni/TiO2 cat-alysts as a function of pressure for the producticn of higher molecular welght paraffins is opposite ~o that of 26 Ni/A1203. As Table VI shows it is most desirable to run 27 the ~i/TiO2 ca~alysts at low pressures to maximize produc-28 tion of higher molecular welght paraffins whereas hlgh pres-sures are necessary for ~i/A1203. This is a clesirable char-acteristlc of TiO2 or ~itanium-containing oxicle-supported .~

~L~77525 1 nickel ca~alysts since no compression of the syn~hesis gas 2 would be required to operate a gasification-liquld fuels syn;
3 thesis plant to maximize production of the desirable parafin 4 liquids.
5 ExAMpLE 3 6 The advantage of TiO2 or titanium-containing oxide- ;
7 supported nickel catalysts in suppress:ing the formation of 8 nickel carbonyl in the presence of C0 was demons~rated using ~
9 infrared spect~oscopy. Nickel ls known to reac~ with carbon ~.
lo monoxide to f~rm volatile nickel carbonyl ~i(C0)4 which can result in a loss of nickel from the catalyst and the pro-12 duction of a poisonous effluent, i.e. ~i~C0)~. The formation 13 of Ni(C0)4 is suppressed on TiO2 or ~itanium-containing 14 oxide-supported nickel catalysts compared to nickel on other supports such as A1203, SiO2, and graphite.
16 The rate of Ni~C0)4 formation from a 10% Ni/TiO2 17 cata~yst was co~pared to ~hà~ from a 10% Ni/SiO2 catalyst. ~:
8 The 10% Ni/SiO2 catalyst was prepared by thoroughly mixing 19 10 g o~ SiO2 having a sur~ace area of 300 m2g 1 with 22 ml of nickel nitrate solution containing 1.11 g nickel. The 21 resulting material was dried in air at 120C, overnight.
22 The 10% ~i/TiO2 and 10% NitSio2 were, i~ separate 23 experiments, pressed into thin wafers weighing 27-29 milli~
24 grams and charged to a cell identical to that described by D. J. C. Yates, W. F. Taylor a~d J. H. Sinfelt, J. Am. Chem.
26 Soc., 86, 2996 (1~64~. The air was evacuated from the cell 27 and hydrogen flow initiated throu~h the cell at 12 l/hr.
28 The cell was rotated so that the wafer was a~ the sili~a end 29 of the cell which was then inserted into a furnace. The wafers were reduced in hydrogen for 1 hour a~ 500C. and - 20 ~

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evacuated for 10 min. at the same temperature to remove 2 hydrogen. The wafers were then cooled in vacuum to room 3 temperature and the cell rvtated so tha~ the infrared win-4 dows were in the spectrometer beam. me wafers in these ex-periments were kept out of the infrared beam so tha~ the 6 formation of Ni(C0)~ in the gas phase could be monitored by 7 in~rared spectroscopy.
8 C0 was added to each catalyst at a pressure of 9 1.87 kPa and the concentration o~ Ni~C0)4 in the gas phase ~
lo due to reactlon of CO with nickel in the ca~alysts was ~ol- -11 lowed as a func~ion of time. Figure 2 shows a plot of the 12 optical density o~ Ni(C0)4 which is proportional to the con-13 centration o~ ~i(C0)~ in the gas phase around the catalyst 14 as a function of time. The 10% Ni/TiO2 catalyst is seen to be much less reactive toward Ni(C0)~ formation than nickel 16 on SiO2- The TiO2 and titanium-contain~ng oxide-supported 17 nickel catalysts thus have the desirable property of in-18 hibiting the formation of Ni(C0)4-~L~77~Z~
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2 Rhodium catalysts with improved seLectivity to hydrocarbons with carbon chain lengths of two to five car-4 bon atoms and lmproved selectivity to olefinic hydrocarbons in thls carbon number range are obtained by depositing 6 rhodium on TiO2 and other titanium-containing oxide supports.
7 Thuq, a 2 w~. % Rh/TiO2 catalyst is prepared by stirring to-8 gether ~0 grams of TiO2 with 4.08 ml of RhCl3 solu~.ion con-9 taining 0.408 grams of rhodium. The TiO2 was prepared by the flame hydrolysis of TiCl4 and had a surface area of 60 m2g;l.
11 Titania prepared by other techniques su~h as precipita~ion 12 and calcination of a suitable salt is also satlsfactory.
13 After thoroughly mixing the TiO2 and rhodium solution the 14 mixture is dried in air at 120C. overnigh~.
To illustrate the desirable c~aracteristics of 16 Rh/TiO2 it was compared to rhodium dispersed on A1203. Thus 17 a 2% Rh/A1203 catalyst was prepared by mixing 5 grams of 18 Al203 with 3.52 ml of RhCl3 solution containing 0.102 grams 9 of rhodium. The resulting mixture was dried in air at llO-l20C. ov~rnight.
21 Table VII illustrates the desirable characteristics 22 of T102 or titan~um-contalning oxide-supported rhodium cata-23 lysts. The Rh/TiO2 shows improved selectivity to hydrocar-24 bons with carbon chain lengths of two to five hydrocarbons at all H2/C0 ra~ios. T~usg at an H2/C0 r~tio of l~65 26 mole 26 % o~ the products are C2 C5 hydrocarbons whereas Rh/A1203 27 produces only 14 mole % hydrocarbons in this carbon number 28 range. Rh/TiO2 also shows lncreased selectivity to olefins ~ r 29 compared to Rh/Al~030 As Table VII demonstra~es, the ratio of ethylene to ethane ls greater at all conditions for ~:

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1 Rh/TiO2 compared to Rh/Alz03. Rh/TiO2 thus e~ibi~s the de-2 sirable characteristics of improved selectivity to C2wC5 3 llydrocarbons and olefins, these hydrocarbons being hig~ly 4 desilrable as chemical interDledia~ces for the production of S plastics9 rubbers, alcohols, ketones, aldehydes, e~ters and 6 acids.
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Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE PROPERTY OR PRIVILEGE
IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A process for the synthesis of hydrocarbons characterized by passing a mixture of H2 and CO at a H2/CO ratio of 0.1 to 10 over a ruthenlum, nickel or rhodium on titanium oxide catalyst at a space velocity of up to 50,000 V/V/Hr., at a temperature of from 100 to 500°C and at a pressure of from 100 to 105 kPa for a time sufficient to effect the generation of the desired hydrocarbon pro-ducts in the desired ratio.

2. The process of claim 1 wherein the titanium-containing oxide is selected from the group consisting of TiO2, ZrTiO4, TiO2-carbon, TiO2-A1203, TiO2-SiO2, alkaline earth titanate, alkali titanates and rare earth titanates.

3. The process of claim 1 wherein the titanium-containing oxide is TiO2.

4. The process of any one of claims 1, 2 or 3 wherein the titanium-containing oxide has a surface area of from 1 to 200 m2g-1.

5. The process of claim 3 wherein the TiO2 has a surface area of from 25 to 100 m2g-1.

6. The process of any one of claims 1, 2 or 3 wherein the catalyst con-sisting of ruthenium supported on a titanium-containing oxide has a ruthenium concentration of rom 0.01 to 15 wt.% and a ruthenium particle crystallite size of from 1 to 20 nm.

7. The process of any one of claims 1, 2 or 3 wherein the catalyst con-sisting of ruthenium supported on a titanium-containing oxide has a surface area of from 10 to 60 m2g-1.

8. The process of any one of claims 1, 2 or 3 wherein the catalyst con-sisting of nickel supported on a titanium-containing oxide has a nickel concen-tration of from 0.01 to 75 wt.% and a nickel particle crystallite size of from 1-30 nm.

9. The process of any one of claims 1, 2 or 3 wherein the catalyst con-sisting of rhodium supported on a titanium-containing oxide has a rhodium con-centration of from 0.01 to 10 wt.% and a rhodium particle crystallite size of from 1 to 20 nm.

10. The process of claim 1 wherein the catalyst consisting of ruthenium supported on a titanium-containing oxide has a ruthenium particle crystallite size of less than 5 nm, the nickel supported on a titanium-containing oxide has a nickel particle crystallite size of less than 10 nm, and the rhodium supported on a titanium-containing oxide has a rhodium particle crystallite size of less than 5 nm.