GB1583571A - Hydrocarbon synthesis from co and h2 with ru ni or rh supported on a titanium oxide - Google Patents

Description

PATENT SPECIFICATION ( 11) 1 583 571

- ( 21) Application No 26596/77 ( 22) Filed 24 Jun 1977 ( 19) ( ( 44) Complete Specification Published 28 Jan 1981, ( 51) INT CL 3 C 07 C 1/02 ' ' ( 52) Index at Acceptance, Uis C 5 E 221 222 332 386 391 CF ( 72) Inventors: MERLIN ALBERT VANNICE ROBERT LEE GARTEN ( 54) HYDROCARBON SYNTHESIS FROM CO AND H 2 WITH Ru, Ni, OR Rh SUPPORTED ON A TITANIUM OXIDE ( 71) We, EXXON RESEARCH AND ENGINEERING COMPANY, a Corporation duly organised and existing under the laws of the State of Delaware, United States of America, of Linden, New Jersey, United States of America, do hereby declare the invention for which we pray that a patent may be granted to us, and the method by which it is to be

performed, to be particularly described in and by the following statement: 5

The present invention relates to a process for the synthesis of hydrocarbons from carbon monoxide and hydrogen.

According to the present invention, there is provided a process for the synthesis of hydrocarbons comprising passing H 2 and CO at H 2/CO ratio of 0 1 to 10 over a catalyst of ruthenium, nickel or rhodium supported on a titanium-containing oxide at a space velocity of 10 up to 50,000 V/V/Hr and at a temperature of from 100 to 500 C, at a pressure of from 100 to 105 k Pa for a time sufficient to effect the generation of the desired hydrocarbon products in the desired ratio.

In this patent specification, pressures are given in kilopascals (k Pa) wherein a pascal is

1 450 x 10-4 pounds/in 2 15 It was discovered by Pichler (see H Pichler, Brenstoff-Chem 19, 226 ( 1938), H Pichler and H Buffleb, Brennstoff-Chem 21,247,273,285 ( 1940)) in 1938 that Ru can produce at low temperatures and very high pressures, high molecular weight paraffinic waxes Because it is such a good hydrogenation catalyst, ruthenium has not been noted for its capability to produce olefins This is shown by the only study conducted under typical synthesis conditions 20 using supported Ru where at 2160 k Pa, 220-240 C and H 2/CO ratios of 1 to 3, it was noted that the hydrocarbon product contained only "moderate" amounts of olefins (see F S Karn et al, I&EC Product Res & Devel 4,265 ( 1965)) At a H 2/CO ratio of 1, over 85 wt %of the hydrocarbon product was composed of C 5 + material In addition, at 100 k Pa and 222 C, methane was the only hydrocarbon product observed It is clear then that typical Ru catalysts 25 would be expected to produce primarily high molecular weight paraffins at moderate pressures and methane as the principal product at atmospheric pressure.

Because itis so expensive, only supported, highly dispersed Ru catalysts can be considered for any commercial synthesis process since only in this state can the catalytic activity of most, if not all, of the Ru atoms to be utilized It is necessary then to prepare these catalysts in such a 30 way that they possess a large Ru surface area thereby reducing the weight loading of Ru required to achieve the desired activity Since it is now possible to produce catalysts in this manner, they may now be seriously considered as candidates for the commercial synthesis of olefins and paraffins from CO and H 2.

A new method for the selective synthesis of olefinic hydrocarbons and particularly olefins 35 of from C 2 to C l chain length inclusive from CO and H 2 at pressures of from 100 to 10 k Pa 3, preferably 100 to 3100 k Pa, comprises the steps of passing a synthesis gas stream comprising CO and H 2 at a H 2/CO ratio of from O 1-10, preferably 0 5-4, most preferably 1-3, at a space velocity of from 100 hr over a catalyst comprising from O 01 to 15 wt % ruthenium on Ti O 2, other titanium-containing oxides or mixtures thereof for a time sufficient to effect the 40 generation of desired olefinic hydrocarbon products at a temperature of from 100 to 500 C, preferably 1500-400 C ' most preferably 150-300 C, and a pressure of from 100 to 105 k Pa ( 1-1000 atm), preferably 100-3100 k Pa, most preferably, 100-2060 k Pa The supported ruthenium catalyst system used in the instant process has a total BET surface area of from 10 to 60 m 2 g-1 with a ruthenium crystallite size of preferably less than 5 mn ( 50 A) 45 2 1,583,571 2 Ruthenium supported on Ti O 2, other titanium-containing oxides or mixtures of of titanium oxides, comprises a catalyst system which exhibits superior hydrocarbon synthesis characteristics in synthesis processes The titanium containing oxide supports which may be used in the practice of this invention are oxides having surface areas of from 1 to 200 m 2 g-1, preferably 10-100 m 2 g-1, most preferably 25-100 m 2 g-1 The oxides are selected from Ti O 2, 5 A 1203-Ti O 2, Si O 2-Ti O 2, Ti O 2-Carbon, Zr Ti O 4, alkaline earth titanates (Ba Ti O 3, Ca Ti On, Si Ti O 3, Mg Ti O 3) alkali titanates (Na 2 Ti O 3, Li 2 Ti O 3, K 2 Ti O 3) and rare earth 'titanates, preferably, the titanium oxide Ti O 2 With most supported metal catalysts, the higher the surface area of the support, the higher the dispersion of the supported metal at a given metal loading It is therefore desirable to use a Ti O 2 with as high a surface area as possible to 10 maximize the dispersion of the ruthenium metal However, when working with Ti O 2, samples with surface areas of 150 to 250 m 2 g-' (usually prepared by precipitation techniques) desurface on heating to 500 C Commercially available Ti O 2 made by flame hydrolysis of Ti C 14 has a stable surface area of 60 m 2 g 1 for thermal treatments at temperatures of 500 C and is therefore the preferred support For thermal treatments at temperatures below 15 500 C, Ti O 2 prepared by precipitation techniques may be successfully employed.

Ruthenium is deposited on the chosen support in a concentration of from 0 01 to 15 wt %, preferably 0 1 to 10 wt %, most preferably 0 5 to 5 wt %, with the ruthenium possessing a crystallite size, as determined by standard techniques such as X-ray diffraction or transmission electron microscopy of from 1 to 20 nm, preferably 1-10 i O nm,'most preferably 1-5 nm 20 Using standard experimental techniques, for a ruthenium on'-Ti O 2 system, reduced in '' hydrogen at 450 C, X-ray diffraction shows no particles of Ru in the reduced catalyst'which indicates particles having crystallite sizes of less than 5 nm, which corresponds to a dispersioni of greater than 20 % ' Ruthenium catalysts supported on Ti O 2, other titanium-containing oxides, or mixtures 25 thereof, exhibit selectivity to olefin products, especially C 2-Clo inclusive olefins Such catalysts, when used in the present system, exhibit improved selectivity to said olefins, improved longevity and tolerance to sulfur and resistance to ruthenium volatization in oxidizing atmospheres as compared with ruthenium catalysts of the prior art which are supported on materials such as A 1203, Si O 2 or carbon -30 The ruthenium catalysts employed in the practice of the present process are themselves prepared by techniques known in the art for the preparation of other catalyst systems, such as Ru on A 1203, etc A suitable rutheniumsalt such as ruthenium chloride, ruthenium nitriate'or ruthenium acetate, etc, is dissolved in a solvent such as water or any suitable solvent and stirred with the chosen titanium oxide system Preferably, the support is Ti O 2 prepared by 35 flame hydrolysis of Ti CI 4, which Ti O 2 has a surface area of " 60 m 2 g After thorough mixing the mixture is allowed to dry and then heat treatedin air at a temperature of from 100 to 150 C or alternatively may be dried immediately by heating in air at a temperature of between 100 and 150 C for several hours.

However, there is afinal step, which is essential, of heat treating the supported ruthenium 40 catalyst, prepared as outlined above, or by similar techniques, in a reducing atmosphere such ' as hydrogen at a temperature greater than 300 C, preferably greter-than 400 C, mo O t preferably, greater than 500 C, for from 5 to 4 hours, preferably 1-2 hours.

Nickel supported on Ti O 2, other titanium-containing oxides or mixtures of various titanium oxides as described above comprises a catalyst system which exhibits superior 45 hydrocarbon synthesis characteristics Such supported nickel catalysts exhibit selectivity to paraffinic hydrocarbon products of from C 2 to C 7 which are free of olefins and oxygenated products They generate CO conversions of up to 60 % at-pressures of 3090 k Pa without significant change in product distribution A large fraction of the product obtained contains 2 or more carbon atoms in the chain up to conversions of 60 % The supported'nickel catalysts 50 exhibit enhanced activity, improved selectivity to higher molecular weight normal paraffins, improved longevity and tolerance to sulfur and resistance to nickel carbonyl formation as compared to nickel catalysts on other supports such as A 1203, silica or carbon.

Conventional nickel catalysts i e Ni/A 1203, Ni/ Si O 2 etc are well known'for their selectivity toward methane formation; for example see M ' Greyson, "Catalysis", Vol IV, 473 55 ( 1956) and H A Dirksen and H R Linden, Research Bulletin #31, Institute of Gas Technology ( 1963) Within a wide range of temperature, pressure and H 2/CO ratios, methane is by far the predominant hydrocarbon product and it is this fact that has made nickel the catalyst of choice for commercial methane synthesis from CO and H 2 '.

Nicel has been dispersed on and co-precipitated with a wide variety of typical oxide 60 supports and no major effect on product distribution has been noted'When higher hydrocarbons have been observed, they are still usually gaseous materials consisting primarily of ethane and only small quantities of C 3 ' hydrocarbons The effect of a large number of promoters on the activity and selectivity of nickel catalysts has been studied'ind Th O 2 is the only material to have a pronounced influence on the product distribution Usually used with 65 1,583,571 Ni/Kieselguhr catalysts, the addition of 12-24 parts Th O 2 per 100 parts Ni results in up to 60-70 wt % of the total hydrocarbon product present as C 5 + material including solids and liquids (see R B Anderson, "Catalysis", Vol IV, p 53 ( 1956)) No other promoters have been documented as being capable of inducing this change in product selectivity Although catalyst activity was increased somewhat by the addition of Th O 2, the increases were not 5 large, normally consisting of increases upto 10 % in the H 2 + CO conversion.

Therefore, nickel catalysts have been used frequently in the past to synthesize methane from CO and H 2, and are quite selective in producing this product With the exception of catalysts promoted with Th O 2, they were not known to possess the capability of producing large quantities of higher molecular weight prodcts This invention discloses the modification 10 of the catalytic behavior of nickel by dispersing it upon Ti O 2 or a Ticontaining support resulting in a catalyst which is employed in a process which yields a much higher average molecular weight product The highly desirable effect of greatly increasing the activity of the nickel component is also obtained.

A new method for the selective synthesis of higher molecular weight normal paraffins from 15 CO and H 2 over a wide range of CO conversions at pressures of from 103 to 3090 k Pa comprises the steps of passing a synthesis gas stream comprising CO and H 2 at a H 2/ CO ratio of from 0 1-10, preferably 0 5-4, most preferably 1-3 at a space velocity of from 100 hr -' to 50,000 hr over a catalyst comprising from 0 01 to 75 wt % Ni on Ti O 2, other titaniumcontaining oxides or mixtures of said titanium-containing oxides for a time sufficient to effect 20 the generation of desired paraffinic products at a temperature of from 100 to 5000 C, preferably 150-4000 C, most preferably 150-3000 C and a pressure of from 103-1 03 x 10 k Pa, preferably 103-3090 k Pa, most preferably 103-2060 k Pa The supported nickel catalysts system has a total BET surface area of from 10 to 60 m 2 g lof total catalyst with a nickel crystallite size of preferably less than 10 nm ( 1 OOA) (as measured by Xray diffraction) A 25 suitable size range is 1-30 nm, preferably 1-10 nm, most preferably 1-7 5 nm.

Using standard experimental techniques, 10 %Ni/Ti O 2 reduced in hydrogen at 450 C (as in the following examples) evaulated by X-ray diffraction exhibited a crystallite size of 7 5 nm which corresponds to a nickel dispersion of about 14 % For a 1 5 % Ni/Ti O 2 system, the particle size is less than 5 nm since Ni metalwas not detectable by X-ray This corresponds to 30 a dispersion of greater than 20 %.

The nickel catalysts employed in the practice of the present process are themselves prepared by techniques similar to those described above for ruthenium.

A supported Ni/Ti O 2 catalyst can also be prepared by reduction of the compound Ni Ti O 3 which on reduction in hydrogen at temperatures of about 450 C decomposes into nickel 35.

metal supported on Ti O 2 Reduction of the stoichiometric Ni Ti O 3 to Ni/Ti O 2 gives a catalyst of composition 38 wt % Ni/Ti O 2.

The final step of heat treating is as described above for the supported ruthenium catalyst.

The present process will selectively generate C 2 ' normal paraffins from CO and H 2 in conjunction with the above-described nickel catalyst systems provided operation is con 40 ducted at a temperature below 5000 C Use of the catalyst also allows synthesis to be run at temperatures lower than those disclosed in the prior art with equivalent product yields and

CO conversion rates and such superior results are obtained when using catalysts possessing Ni weight loadings equal to those of the prior art.

Rhodium catalysts for the production of higher molecular weight hydrocarbons from CO 45 and H 2 have been reported only in a Bureau of Mines Study (J F Shultz et al, U S Bureau of Mines Report #6974, 1967) This study showed that rhodium supported on A 1203 produced + wt % methane at typical H 2/CO ratios, 2163 k Pa pressure and at temperatures from 440-580 C Because of its expense and low activity compared to other metals, rhodium was reported by these workers to be unattractive as a methanation catalyst 50 It has now been found, however, that rhodium dispersed on Ti O 2 or other titaniumcontaining oxide supports as described above has high activity and altered selectivity.

Compared to A 1203-supported rhodium, the use of Ti O 2 or titaniumcontaining oxidesupported metal in olefin preparation processes results in a process which exhibits a marked decrease in methane in the products with a concomitant increase in the formation of higher 55 molecular weight paraffins and olefins.

A new method for the improved synthesis of olefinic hydrocarbons and particularly olefins of from C 2 to C 5 chain length inclusive,-and most particularly, C 3 and C 4 hydrocarbons from CO and H 2, comprises the steps of passing a synthesis gas stream comprising CO and H 2 at a H 2/CO ratio of from 0 1-10, preferably 0 5-4, most preferably 1-3 at a space velocity of from 60 hr-' to 50,000 hr-' over a catalyst comprising from 0 01 to 10 wt % rhodium on Ti O 2, other titanium-containing oxides or mixtures thereof for a time sufficient to effect the generation of desired olefinic hydrocarbon products in the desired ratio, said contacting being effected at a temperature of from 100 to 500 C, preferably 150-400 C, most preferably 150-300 C and a pressure of from 100 to 10 ' k Pa, preferably 100 to 3000 k Pa, most 65 4 1583 71 4 preferably 100-2000 k Pa The supported rhodium catalyst system used in the instant process has a total BET surface area of from 10 to 60 m 2 g-' with a rhodium crystallite size of preferably less than 5 nm.

Rhodium is deposited on the chosen support in a concentration of from 0 01 to 10 wt %o, preferably O 05-5 wt %, most preferably O 1-2 wt %, with the rhodium possessing a crystallite 5 size, as determined by standard techniques such as X-ray diffraction or transmission electron microscopy of from 1 to 20 nm, preferably 1-10 nm, most preferably 1-5 nm.

Using standard experimental techniques, for a rhodium on Ti O 2 system reduced in hydrogen at 450 WC, X-ray diffraction shows no particles of rhodium in the reduced catalyst which indicates that the rhodium crystallites possess an average size of less than 5 nm, which 10 corresponds to a dispersion of greater than 20 %.

The rhodium catalysts employed in the practice of the instant process are themselves prepared by techniques similar to those described above for ruthenium.

The final step of heat treating is as described above for the supported ruthenium catalyst.

Use of the above-identified catalyst in the present process at reaction conditions equivalent 15 to those of the prior art gives superior results (in the way of improved selectivity and greater product yields) when catalysts possessing rhodium with loadings equal to those of the prior art are used.

EXAMPLE 1

Ruthenium catalysts with improved selectivity to olefin products and to hydrocarbons with 20 carbon chain lengths of two carbons to ten carbons are obtained by depositing ruthenium on Ti O 2 or titanium-containing oxide supports Thus, a 2 % Ru/Ti O 2 catalyst is prepared by stirring together 10 grams of Ti O 2 and 3 ml of Ru C 13 solution containing 0 2 g of ruthenium.

The Ti O 2 is prepared by the flame hydrolysis of Ti CL 4 to give a support with 60 m 2 g X surface area Titania made by other techniques such as precipitation and calcination of a suitable salt 25 is also satisfactory After thoroughly mixing the Ti O 2 and the ruthenium solution, the mixture is dried overnight in air at 110-120 'C.

To illustrate the desirable properties of Ru/Ti O 2 catalysts, they were compared to ruthenium supported on conventional supports such as A 1203 or carbon Thus, a 5 % Ru/ -0 a A 1203 catalyst was prepared by thoroughly mixing 5 26 ml of Ru C 13 solution containing 30 0.526 grams of ruthenium with 10 grams of a 7-A 1203 The resulting mixture was dried overnight in air at 110-1200 C A 4 % Ru/carbon catalyst was prepared by thoroughly mixing 6 ml of Ru C 13 solution containing 0 12 grams of ruthenium with 3 grams of carbon with a surface areaof 1000 m 2 g ' The resultant mixturewas driedovernight in airat 110-120 'C.

The desirable selectivity characteristics of Ti O 2 or titaniumcontaining oxide-supported 35 ruthenium catalysts compared to other supports are demonstrated in Tables I, II and III At 103 k Pa total pressure Ru/Ti O 2 shows a markedly different product distribution from Ru/A 1203 The formation of methane and very high molecular weight hydrocarbons is suppressed over the Ru/Ti O 2 catalysts giving a product spectrum in which the carbon chain length range of two to give carbon atoms is maximized For Ru/A 1203, much more methane 40 and higher molecular weight hydrocarbons are produced Ru/Ti O 2 also possesses the desirable characteristics that a large fraction of the C 2-C 5 products is olefinic Thus, this catalyst is particularly suitable for producing from CO and H 2 a product stream which is highly olefinic and with carbon chain lengths of two to five carbon atoms Olefins such as ethylene, propylene, butenes and pentenes in this range are particularly desirable as chemical inter 45 mediates for the production of plastics, rubber, alcohols, ketones and aldehydes, esters and acids.

Table II illustrates the desirable selectivity characteristics of Ti O 2 of titanium-containing oxide-supported ruthenium catalysts at higher total pressures of reactants At 103 k Pa the Ru/Ti O 2 makes less methane and C 8 + hydrocarbons than Ru/A 1203 with most of the 50 products from Ru/Ti O 2 being in the C 2 to C 7 carbon number range Ru/Ti O 2 thus exhibits improved selectivity to the desirable C 2 to C 7 hydrocarbons Table II also illustrates the improved selectivity to olefins of Ru/Ti O 2 compared to Ru/A 1203 In the C 2 to C 5 carbon number range 42 % of the products are olefins with Ru/Ti O 2 whereas only 25 % are olefins with Ru/A 1203 Ru/Ti O 2 is thus more selective for the production of the desirable olefins 55 with carbon chain lengths of two to five carbon atoms.

Table III compares Ru/Ti O 2 with ruthenium on a variety of other supports Ruthenium supported on Ti O 2 or titanium-containing oxide supports produces 42 wt % of the products with carbon chain lengths of two to five carbon atoms, while ruthenium on A 1203, carbon or ruthenium metal produce only 31 %, 2 % and 25 %, respectively of products in this carbon 60 number range In addition, the fraction of olefins in the products is greatest for Ru/Ti O 2 as indicated by the ethylene/ethane ratios for each catalyst Ruthenium on A 1203 or carbon, or unsupported ruthenium metal produce little or no ethylene in the C 2 fraction from CO and H 2 under the reaction conditions used in Table III whereas Ru/Ti O 2 produces about one-half of the C 2 fraction as ethylene 65 1,583,571 1,583,571 Catalyst (a) 2 % Ru/Ti O 2 % Ru/A 12 03 TABLE I

Selectivity of Ruthenium Catalysts (Reaction Conditions: H 2/CO = 1, Pressure = 103 k Pa) Temp % CO Product Total ( C) Cony Carbon Number wt % 262 0 7 C 1 26 C 2 17 C 3 28 C 4 19 Cs 10 C 6 + 267 1 7 C 1 47 C 2 13 C 3 21 C 4 7 Cs 6 C 6 + 5 wt % Olefin 12 wt % Paraffin 8 4 ( 1 atm= 103 k Pa) (a) Each catalyst reduced I hour at 4500 C prior to introducing feed at the reation temperature.

is Catalyst(a) 2 % Ru/Ti O 2 % Ru/ r 7 -A 1203 TABLE II

Selectivity of Ruthenium Catalysts (Reaction Conditions, H 2/CO = 1, Pressure = 980 k Pa) Temp ( C) % CO Conv Product Carbon Number 267 274 Ci C 2 C 3 C 4 C 5 C 6 C 7 C 8 + Cl C 2 C 3 C 4 C 5 C 6 C 7 C 8 + Total wt% Wt% Olefin 14 6 21 17 13 24 6 16 11 12 11 9 2 14 16 8 1 12 6 wt% Paraffin 4 7 4 7 4 ( 1 atm = 103 k Pa) (a) Each catalyst reduced 1 hour at 450 C prior to introducing feed at the reaction temperature.

0 \ Lt A 00 Lit t-^ TABLE III

Selectivity of Ruthenium Catalysts.

(Reaction Conditions: H 2/CO = 3, Pressure = 103 k Pa) Catalyst 2 % Ru Ti O 2 (a) %Ru/A 123 a (a) 4 % Ru/Carbon (b) Ru Metal Powder (c) T C % CO Cony.

228 1 8 229 10 6 234 1 6 217 27 1 CH 4 C 2 H 4 C 2 H 6 ' 9 1 2 Product Mole % C 3 H 6 I Cal 16 C 3 H 8 (a) Catalysts reduced for 1 hour at 450 C before feed introduced.

(b) Catalyst reduced 1 hour at 400 C before feed introduced.

(c) Catalyst reduced 1 hour at 300 C before feed introduced.

C 4 Hlo C 4 H 10 9.

Cs H'o C 5 H 12 O Cs+ C 6.

4 0 ' O (i o 00 c 1,583,571 EXAMPLE 2

Catalysts with improved activity and selectivity to normal paraffin products with carbon chain lengths of two and higher are obtained by depositing nickel on Ti O 2 and other titanium-containing oxide supports Thus, a 1 5 % Ni/Ti O 2 catalyst is prepared by stirring 11 4 ml of nickel nitrate solution containing 0 39 g of nickel with 25 g of Ti O 2 in a beaker The 5 Ti O 2 was prepared by flame hydrolysis of Ti CI 4 and had a surface area of 60 m 2 g 1 Titania made by other techniques such as precipitation and calcination of a suitable titanium salt is also satisfactory After thoroughly mixing the nickel solution with the Ti O 2 the resulting material is dried in a dessicator overnight and further dried in air in an oven at 120 C.

overnight Alternatively the resulting material can be dried immediately at 120 C in air for 10 several hours A 10 %Ni/Ti O 2 catalyst is prepared by mixing with a spatula in a beaker 20 g of Ti O 2 with 11 1 g Ni NO 3 6 H 20 dissolved in 5 ml of distilled water The resultant material is dried in a dessicator overnight and further dried at 120 C in air overnight By impregnating the dried 10 % Ni/Ti O 2 catalysts with additional quantities of nickel nitrate solution concentrations of Ni/Ti O 2 up to -75 wt % can be obtained 15 To illustrate the desirable characteristics of the Ni/Ti O 2 catalysts, they were compared to several commercial nickel catalysts and to several nickel catalysts supported on A 1203 and Si O 2 Thus a 5 % Ni/l -AI 203 catalyst was prepared by thoroughly mixing 9 5 g of q-AI 203 having a surface area of 245 m 2 g with 6 6 ml of nickel nitrate solution containing O 5 g nickel The resulting mixture was dried overnight in air at 110 C A 16 7 % Ni/Si O 2 catalyst 20 was prepared by thoroughly mixing 10 g of silica having a surface area of 300 m 2 g-1 with 20 ml of nickel nitrate solution containing 2 g of nickel The resulting material was dried overnight in air at 110 C.

A series of supported nickel catalysts and bulk nickel oxide were reduced in hydrogen at 450 C for one hour prior to the introduction of a CO-H 2 feed at a temperature of 205 C The 25 enhanced activity of the Ti O 2-supported nickel catalysts relative to a variety of other nickel catalysts is shown in Table IV The 10 % Ni/Ti O 2 catalyst is much more active on a per gram of catalyst basis than other nickel catalysts containing much larger quantities of nickel.

TABLE IV

30 ACTIVITIES OF NICKEL CATALYSTS FOR CO-H 2 REACTION (CO-H 2 Reaction Conditions: 205 O C, 103, k Pa, H 2/CO= 3) i Moles CO g Moles CO 35 Converted/Sec/ Converted/Sec/ Catalyst (a) Gram Nickel Gram Catalyst %Ni/,a-AI 203 3 44 0 172 8 8 % Ni/h A 1203 1 63 O 143 40 42 %Ni/a-AI 203 0 21 0 088 16.7 % Ni/Si O 2 2 36 0 394 20 % Ni/graphite 0 064 0 082 45 Bulk Ni Metal 0 032 0 032 % Ni/Ti O 2 22 8 2 28 1 53 % Ni/Ti O 2 8 35 0 113 50 (a) All catalysts reduced 1 hr at 450 C prior to activity test.

Ti O 2 or titanium-containing oxide-supported nickel catalysts also exhibit desirable selectivity characteristics compared to bulk nickel or nickel on Si O 2 or A 1203 supports This is 55 demonstrated in Table V Nickel on a variety of supports, e g A 1203, Si O 2, graphite and bulk nickel produce methane almost exclusively with only small amounts of hydrocarbons with carbon chain lengths up to 4 The Ti O 2 or titanium-containing oxidesupported nickel catalysts show a large reduction in methane make and increase in paraffin products with carbon chain lengths of two carbon atoms and higher This is especially desirable for the 60 production of storable liquid fuels from CO-H 2 mixtures obtained from coal gasification.

The increased selectivity of Ti O 2 or titanium-containing oxidesupported nickel catalysts is maintained over a range of conversions up to -50 % as demonstrated in Figure 1 Nickel catalysts prepared from other supports, however, show much poorer selectivity to high molecular weight paraffins than Ti O 2 or titanium-containing oxidesupported metal catalysts 65 1.583,571 ' The selectivity of the Ti O 2 or titanium-containing oxide-supported nickel catalysts to hydrocarbons with carbon chain lengths of 2 and higher is also maintained at higher pressures compared to nickel on other supports This is demonstrated in Table VI The behavior of the Ni/Ti O 2 catalysts as a function of pressure for the production of higher molecular weight paraffins is opposite to that of Ni/A 1203 As Table VI shows it is most desirable to run the 5 Ni/Ti O 2 catalysts at low pressures to maximize production of higher molecular weight paraffins whereas high pressures are necessary for Ni/A 1203 This is a desirable characteristic of Ti O 2 or titanium-containing oxide-supported nickel catalysts since no compression of the synthesis gas would be required to operate a gasification-liquid fuels synthesis plant to maximize production of the desirable paraffin liquids 10Example 3

The advantage of Ti O 2 or titanium-containing oxide-supported nickel catalysts in suppressing the formation of nickel carbonyl in the presence of CO was demonstrated using infrared spectroscopy Nickel is known to react with carbon monoxide to form volatile nickel carbonyl Ni(CO)4 which can result in a loss of nickel from the catalyst and the production of a 15 poisonous effluent, i e Ni(CO)4 The formation of Ni(CO)4 is suppressed on Ti O 2 or titanium-containing oxide-supported nickel catalysts compared to nickel on other supports such as A 1203, Si O 2, and graphite.

The rate of Ni(CO)4 formation from a 10 % Ni/Ti O 2 catalyst was compared to that from a 10 % Ni/Si O 2 catalyst The 10 % Ni/Si O 2 catalyst was prepared by thoroughly mixing 10 g of 20 Si O 2 having a surface area of 300 m 2 g with 22 ml of nickel nitrate solution containing 1 11 gnickel The resulting material was dried in air at 120 C overnight.

The 10 % Ni/Ti O 2 and 10 % Ni/Si O 2 were, in separate experiments, pressed into thin wafers weighing 27-29 milligrams and charged to a cell identical to that described by D J C.

Yates, W F Taylor and J H Sinfelt, J Am Chem Soc, 86, 2996 ( 1964) The air was 25 evacuated from the cell and hydrogen flow initiated through the cell at 12 1 /hr The cell was rotated so that the wafer was at the silica end of the cell which was then inserted into a furnace The wafers were reduced in hydrogen for 1 hour at 500 C and evacuated for 10 min.

at the same temperature to remove hydrogen The wafers were then cooled in vacuum to room temperature and the cell rotated so that the infrared windows were in the spectrometer 30 beam The wafers in these experiments were kept out of the infrared beam so that the formation of Ni(CO)4 in the gas phase could be monitored by infrared spectroscopy.

CO was added to each catalyst at a pressure of 1 87 k Pa and the concentration of Ni(CO)4 in the gas phase due to reaction of CO with nickel in the catalysts was followed as a function of time Figure 2 shows a plot of the optical density of Ni(CO)4 which is proportional to the 35 concentration of Ni(CO)4 in the gas phase around the catalyst as a function of time The 10 % Ni/Ti O 2 catalyst is seen to be much less reactive toward Ni(CO)4 formation than nickel on Si O 2 The Ti O 2 and titanium-containing oxide-supported nickel catalysts thus have the desirable property of inhibiting the formation of Ni(CO)4.

TABLE V 40

SELECTIVITY OF NICKEL CATALYSTS P= 103 k Pa, H 2/CO= 3 45 Mole % Paraffin of each Carbon Number Catalyst T C % CO Conversion C 1 C 2 C 3 C 4 C 5 + 10 %Ni/Ti O 2 243 24 50 9 25 8 9 50 1.5 % Ni/Ti O 2 251 13 3 58 14 12 8 7 Bulk Ni 252 7 9 94 6 42 % Ni/a-A 1203 236 2 1 76 14 5 3 1 55 8.8 % Ni/r-A 12 O 3 230 3 1 81 14 3 2 % Ni/1-AI 2 03 254 10 8 90 7 3 1 16 7 % Ni/Si O 2 220 3 3 92 5 3 1 60 % Ni/grahite234 2 8 87 7 40 % Ni/graphite 234 24 8 87 7 4 1 TABLE VI

SELE C Tl VITY O F NICKEL CATALYSTS AT VARIOUS PRESSURES (Reaction Conditions: H 2 /CO = 3, T = 200206 'C) Catalyst % Ni/Ti O, 31 4 % Ni/ a-A 1203 Pressure (A TM) 1 1 % CO Conversion 4 3.5 4.5 2.1 1.9 1.3 cl 50.5 56 57.5 69 C 2 21.5 37 16 29 Mole % Product C 3 7.5 5.5 5.5 4 1 ATM = 103 k Pa C 4 7.5 1.5 2 00 ('3 1.583571 EXAMPLE 4

Rhodium catalysts with improved selectivity to hydrocarbons with carbon chain lengths of two to five carbon atoms and improved selectivity to olefinic hydrocarbons in this carbon number range are obtained by depositing rhodium on Ti O 2 and other titanium-containing oxide supports Thus a 2 wt % Rh/Ti O 2 catalyst is prepared by stirring together 20 grams of 5 Ti O 2 ' with 4 08 ml of Rh C 13 solution containing 0 408 grams of rhodium The Ti O 2 was prepared by the flame hydrolysis of Ti C 14 and had a surface area of 60 m 2 g-' Titania prepared by other techniques such as precipitation and calcination of a suitable salt is also satisfactory After thoroughly mixing the Ti O 2 and rhodium solution the mixture is dried in air at 120 WC overnight 10 To illustrate the desirable characteristics of Rh/Ti O 2 it was compared to rhodium dispersed on A 1203 Thus a 2 % Rh/A 1203 catalyst was prepared by mixing 5 grams of A 1203 with 3 52 ml of Rh C 13 solution containing 0 102 grams of rhodium The resulting mixture was dried in air at 110-120 'C overnight.

Table VII illustrates the desirable characteristics of Ti O 2 or titaniumcontaining oxide 15 supported rhodium catalysts The Rh/Ti O 2 shows improved selectivity to hydrocarbons with carbon chain lengths of two to five hydrocarbons at all H 2/CO ratios Thus, at an H 2/CO ratio of 1 6, 26 mole % of the products are C 2-C 5 hydrocarbons whereas Rh/A 1203 produces only 14 mole % hydrocarbons in this carbon number range Rh/Ti O 2 also shows increased selectivity to olefins compared to Rh/A 1203 As Table VII demonstrates, the ratio of 20 ethylene the ethane is greater at all conditions for Rh/Ti O 2 compared to Rh/A 1203.

Rh/Ti O 2 thus exhibits the desirable characteristics of improved selectivity to C 2-C 5 hydrocarbons and olefins, these hydrocarbons being highly desirable as chemical intermediates for the production of plastics, rubbers, alcohols, ketones, aldehydes, esters and acids:

1 1 t,.

Table VII

Selectivities of Rhodium Catalysts (Reaction Conditions: Pressure = 100 k Pa) Mole Product % Temp % CO H 2 ( C) Cony CO 248 265 CH 4 0.3 0 6 63 7 1.3 1 6 74 3 3.3 3 0 80 2 5.3 6 0 86 1 1.6 3.5 5.2 13.9 0.6 74 2 1.6 85 0 3.0 90 0 6.0 93 0 C 3 H 6 C 4 H 8 C 2 H 4 C 2 H 6 C 3 H 8 C 4 H 10 0 '19 2 14 3 11 4 7 14 8 12 3 6 3 3 11 2 11 2 1 (a) Each catalyst reduced 1 hour at 450 O C before feed introduced at reaction temperature.

Catalyst (a) 2 % Rh/Ti O 2 2 % Rh/AI 203 C 6 + 0 0 0 Cs Hlo C 5 H 12 0 1 2 1 0 0 00 v L -3 0 0 0 1,583,571

Claims (14)

WHAT WE CLAIM IS:-

1 A process for the synthesis of hydrocarbons comprising passing H 2 and CO at a H 2/CO ratio of 0 1 to 10 over a catalyst or ruthenium, nickel or rhodium supported on a titanium-containing oxide at a space velocity of up to 50,000 V/V/Hr and at a temperature of from 100 to 500 C, at a pressure of from 100 to 105 k Pa for a time sufficient to effect the 5 generation of the desired hydrocarbon products in the desired ratio.

2 The process of claim 1 wherein the titanium-containing oxide is selected from Ti O 2, Zr Ti O 4, Ti O 2-carbon, Ti O 2-A 1203, Ti O 2-Si O 2, alkaline earth titanate, alkali titanates and rare earth titanates.

3 The process of claim 1 or claim 2 wherein the titanium-containing oxide is Ti O 2 10

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

The process of claim 3 or claim 4 wherein the Ti O 2 has a surface area of from 25 to 100 m 2 g_ 1.

6 The process of any one of claims 1-5 wherein the catalyst of ruthenium supported on a 15 titanium-containing oxide has a ruthenium concentration of from 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 1-6 wherein the catalyst of ruthenium supported on a titanium-containing oxide has a surface area of from 10 to 60 m 2 g 1.

8 The process of any one of claims 1-5 wherein the catalyst of nickel supported on a 20 titanium-containing oxide has a nickel concentration 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 1-5 wherein the catalyst of rhodium supported on a titanium-containing oxide has a rhodium concentration of from 0 01 to

10 wt % and a rhodium particle crystallite size of from 1 to 20 nm 25 The process of any one of claims 1 to 7 wherein the catalyst of ruthenium supported on a titanium-containing oxide has a ruthenium particle crystallite size of less than 5 nrim.

11 The process of any one of claims 1 to 5 or 8 wherein the catalyst of nickel supported on a titanium-containing oxide has a nickel particle crystallite size of less than 10 nm.

12 The process of any one of claims 1 to 5 or 9 wherein the catalyst of rhodium supported 30 on a titanium-containing oxide has a rhodium particle crystallite size of less than 5 nm.

13 A process for the synthesis of hydrocarbons according to any one of claims 1 to 12 substantially as hereinbefore described.

14 Hydrocarbons synthesized by a process according to any one of claims 1 to 13.

K J VERYARD, 35 15, Suffolk Street, London SW 1 Y 4 HS Agent for the Applicants Printed for Her Majesty's Stationery Office by Croydon Printing Company Limited Croydon, Surrey 1980.

Published by The Patent Office, 25 Southampton Buildings, London, WC 2 A l AY,from which copies may be obtained.