AU2015203898A1 - A catalyst and a process for catalytic conversion of carbon dioxide-containing gas and hydrogen streams to hydrocarbons - Google Patents

Abstract

The invention relates to a catalyst suitable for use in the 5 hydrogenation of carbon dioxide-containing gas, said catalyst comprising spinel phase of the formula [ Fe 2+(Fe 3 +yAl 3+1-y)2041 . Processes for preparing the catalyst and processes for the hydrogenation of carbon dioxide-containing gas in the presence of the catalyst are also disclosed. c 0 u - 3.5 -0 u 40 *CO2 Conve rsion Moil proclivity 0 20 40 60 80 100 Content of Fe 20 3 phase (a), wt%

Description

AUSTRALIA PATENTS ACT 1990 COMPLETE SPECIFICATION A catalyst and a process for catalytic conversion of carbon dioxide-containing gas and hydrogen streams to hydrocarbons The following statement is a description of the invention: 1 A catalyst and a process for catalytic conversion of carbon dioxide-containing gas and hydrogen streams to hydrocarbons 5 Land, air and marine transportation relies almost entirely on the availability of petroleum-derived liquid fuels. Given the limited availability of crude oil and the locations of the oil-producing countries, this dependence poses major security, economic, and environmental problems for the 10western world. Alternative routes for the production of synthetic liquid fuel from sources other than crude oil may be divided into three groups: 15 (i) conversion of coal and natural gas by a two-stage process, i.e., gasification to syngas (a mixture of CO and H2), followed by Fischer-Tropsch (FT) synthesis; (ii) conversion of biomass (cellulose, starch and lipids) by a wide variety of processes; and 20 (iii) conversion of carbon dioxide and water. Among the three groups of conversion processes described above, the group using the most basic raw materials - carbon dioxide and water - is definitely the most attractive long 25 term alternative, with two main routes currently being explored with the aim of establishing the most viable process: artificial photosynthesis through photocatalytic and photoelectrochemical processes and water splitting combined with carbon dioxide hydrogenation. The development of the 30latter route is at a more advanced level, since both stages of the process have been successfully demonstrated at the bench scale.

2 Of the other two processes, those based on syngas are the most highly developed. Synthetic fuels have been produced for the past ninety years from coal and natural gas through a highly endothermic gasification process to syngas, followed 5 by a highly exothermic FT process to produce paraffin mixtures, which are then further processed to a variety of final products. The reference to prior art documents in the following 10discussion is not to be taken as any evidence or admission that such documents form or form part of the common general knowledge in the present technical field. Splitting of water generates hydrogen and oxygen. Oxygen can 15 be combined with natural gas and steam to produce syngas that contains carbon monoxide, carbon dioxide and hydrogen by a process called autothermal reforming (L. Basini and L. Piovesan, "Reduction on Synthesis Gas Costs by Decrease of Steam/Carbon and Oxygen/Carbon Ratios in the Feedstock", Ind. 20 Eng. Chem. Res. 1998, 37, 258-266; Kim Aasberg-Petersen, Thomas S. Christensen,Charlotte Stub Nielsen, Ib Dybkjmr, "Recent developments in autothermal reforming and pre reforming for synthesis gas production in GTL applications", Fuel Processing Technology 83 (2003) 253- 261) . A similar 25 process could be conducted with bio-gas instead of natural gas (McKenzie P. Kohn, Marco J. Castaldi, Robert J. Farrauto, "Auto-thermal and dry reforming of landfill gas over a Rh/y A1203 monolith catalyst", Applied Catalysis B: Environmental 94 (2010) 125-133). Gasification is another option for 30 converting biomass with oxygen to syngas (Richard C. Baliban, Josephine A. Elia and Christodoulos A. Floudas, "Biomass to liquid transportation fuels (BTL) systems: process synthesis and global optimization framework", Energy Environ. Sci., 2013, 6, 267-287) . The syngas produced by all those methods 3 is mixed with hydrogen produced by electrolysis and carbon dioxide from an external source to form a mixture of carbon dioxide, carbon monoxide and hydrogen that is reacted on tubular reactor packed with solid catalyst to generate an 5 organic liquid and a gas that contain hydrocarbons and water containing oxygenates as a by-product. While dealing extensively with the conversion to hydrocarbons of syngas (a mixture of CO and hydrogen that may contain some 10C0 2 ) via the Fischer-Tropsch synthesis, considerably lesser amount of work is reported in the art in respect of CO 2 hydrogenation. The feasibility of a process of carbon dioxide hydrogenation to form liquid fuels depends on the performance of the catalyst used to advance the reaction and on other 15 process variables. US 2,692,274 describes the catalytic reduction of carbon dioxide with hydrogen in the presence of iron oxide which contains 0.5% of copper and 0.8% K. 20 US 5,140,049 discloses a method for producing olefins from H2 and C02 using potassium promoted catalysts of the Fe304/2%K and Fe2.8sCOo.1sO4/2%K. 25 A series of catalysts based on iron and potassium supported on alumina, which optionally contain also copper, i.e., catalysts of the formulas Fe-K/A1203 and Fe-K-Cu/A1203 were reported in US 4,555,526, WO 97/05088 and WO 01/34538. 30J.S.Hong et.al. [Applied Catalysis A, 218, 53-59, 2001] reported the synthesis of Fe-Al-Cu-K catalyst, its in-situ activation by means of hydrogen reduction at 450'C, followed by cooling down to 300'C, at which temperature the reaction 4 was allowed to start in a continuous fixed bed reactor, into which C0 2

:H

2 (1:3) streams were fed. After activation and stabilization at reaction conditions the catalyst contained two phases - iron oxide Fe304 and carbide Fe 5 C2. The best CO 2 5 conversion reported by these authors was around 40%. Riedel et al. [Topics in Catalysis, Vol. 26, p. 41-54 (2003)] report the synthesis of Fe-Al-Cu-K catalyst by the quick addition of an aqueous NH3 solution to a hot nitrate solution 10of iron, aluminum and copper. The precipitate was separated, washed and dried, and then impregnated with aqueous solution of potassium carbonate. Non-stoichimetric, copper-containing spinel based on Fe-Al-O 15 system was reported by Tanaka et. al. as being useful for exhaust gas treatment (JP 2011045840). It has now been found that liquid fuels can be prepared with high productivity by a reaction of carbon dioxide with 20 hydrogen on solid porous catalyst based on iron. The preferred catalyst operative in the present invention comprises iron-containing spinel phase (before activation). In its most general form, spinel phase indicates a mixed oxide having the formula A 2

+B

3 +0 4 . According to the present 25 invention, the divalent ion A 2 + is Fe 2 + and is essentially free of Cu 2 +, whereas the trivalent ion B3+ is Fe3+ in combination with Al+. Thus, the spinel component of the catalyst may be represented by either one of the two formulas: 30 Fe2+ (Fe3+yAl3+1-y) 204 (spinel of Formula 1) wherein y is in the range from 0.05 to 0.95; or (Cu 2 +xFe 2 +1-x) (Fe 3 +yAl 3 +1-y) 204 (spinel of Formula 2) 5 wherein x is in the range from 0.0 to 0.05, i.e., 0.0<x 0.05 and y is in the range from 0.05 to 0.95. According to the notation used herein, a catalyst which 5 consists of hematite and spinel phases together is represented by the formulas: a [Fe2031 [Fe 2 + (Fe 3 +yAl3+1-y) 2041 Formula I a [Fe2031 j[ (Cu 2 +xFe 2 +1-x) (Fe 3 +yAl3+1-y) 2041 Formula II 10 wherein a is <5wt% and $ >95wt%, correspondingly, and x and y are as previously defined. More preferably, however, the catalyst according to the 15 invention does not contain hematite phase and is copper-free. Thus, the preferred catalyst consists of a spinel of Formula 1: Fe2+(Fe3+yAl3+1-y)204; 0.05 y 0.95, preferably 0.25 y 0.75, e.g., 0. 30 y 0 .70. 20 In its most preferred form, the catalyst consists of potassium promoted spinel of Formula 1: K/Fe2+(Fe3+yAl3+1-y)204, wherein y is in the range from 0.05 to 0.95, more preferably from 0.25 to 0.75, even more preferably from 0.3 to 0.7, and 2 5 specifically from 0.4 to 0.6, with the weight ratio Fe:Al:K preferably varying from 100:20:3 to 100:30:10. The formula K/Fe2+ (Fe3+yAl3+1-y) 204 indicates that the potassium is applied onto the surface of the spinel of Formula 1. 30 The catalyst of the invention is prepared by a process comprising dissolving in an aqueous solution at least one ferric compound and at least one aluminum compound, and optionally cupric compound, adjusting, preferably gradually, 6 the pH of the metal-containing solution, e.g., to about 6.0 8.5, by means of an addition of an alkaline agent, whereby co-precipitation of the metals in the form of their hydroxides occurs, separating the solid formed from the 5 liquid phase, and subjecting same to drying and calcination (for dehydration and formation of the spinel phase and optionally hematite phase). Suitable starting materials for use in the preparation of the 10 catalyst are water-soluble ferric and aluminum salts, such as the nitrate salts. The metal nitrates exist in hydrated forms: Fe(N03)3-9H20 and Al(N03)3-9H20, which are especially preferred. The preferred concentrations of the ferric and aluminum salts in the aqueous solution are from 1900 to 2100 15 and 900 to 1100 gram/L, respectively, with the relative amounts of the salts being adjusted to form the desired composition of the catalyst. The water-soluble metal salts, e.g., the nitrates, can be added to the aqueous solution in a solid form in any desired order, or can be pre-dissolved in 20 separate solutions, which are subsequently combined together. Preferably, the weight ratio Al:Fe in the solution is not less than 20:100, e.g., from 20:100 to 30:100. The experimental results reported below indicate that the 25 best catalysts of the invention are the copper-free pure spinel of Formula 1. However, the presence of small amounts of copper, i.e., the catalysts (Cu 2 +xFe 2 +1-x) (Fe 3 +yAl 3 +1-y) 204 (spinel of Formula 2) can still be used, provided that x is less than 0.05. In the event that the catalysts of Formula 2 30are contemplated, cupric salt, e.g., Cu(N03)2-3H20 is added to the solution described above. The adjustment of the pH of the aqueous solution to the range from 6.0-8.5, e.g., 7.0-8.5, especially from 7.5 to 8.0, in 7 order to affect the co-precipitation of the metal hydroxides, is preferably accomplished by means of gradual addition of an aqueous solution of a base, such as ammonium hydroxide, which solution is preferably applied in a dilute form, with 5 concentration of not more than 5% by weight. The gradual addition preferably lasts not less 10 minutes, e.g., not less than 20, 30 or 60 minutes, and may be accomplished by portionwise addition or feeding a stream of ammonium hydroxide solution at a suitably slow flow rate. During pH 10adjustment, the solution of the metals and the slowly added

NH

4 0H solution are preferably held at a temperature below 301C, e.g., at room temperature. The experimental results reported below indicate that a sharp increase of the pH of the aqueous metal solution (e.g., due to a rapid addition of 15 a concentrated alkaline solution) may unfavorably alter the composition of the catalyst, ultimately causing the formation of the hematite phase following the calcination stage. Working with Al:Fe weight ratio as set out above and carefully basifying the solution afford, following the 2 0calcination, the hematite-free spinel of Formula 1. The precipitate formed is separated from the mother liquor, e.g., by filtration or any other solid/liquid separation technique, and is preferably washed with water and dried at 25 temperature in the range of 100-1400C for period of at least 24 h. Before the calcination step, the dried material is preferably treated with an aqueous solution of a potassium salt, e.g., the solid is impregnated with a solution of potassium carbonate, nitrate or acetate until incipient 30 wetness is observed, followed by drying. The impregnation drying cycle may be repeated several times, in order to load the potassium solution onto the surface of the solid. The presence of potassium renders the surface of the catalyst slightly alkaline, and hence increases the affinity of the 8 catalyst towards carbon dioxide, which is an acidic gas. In general, the weight ratio Fe:K is in the range from 100:3 to 100:10. The solid is then subjected to drying in air at a temperature 5 in the range of 100-1400C for period of at least 24 hours followed by calcination in air at a temperature in the range from 400 to 5000C for period of at least 6 h. The catalyst obtained exhibits surface area of not less than 10 80 m 2 /gram, e.g., between 80 and 180 m 2 /gram; pore volume of not less than 0.1 cm 3 /gram, e.g. between 0.1 and 0.5 cm 3 /gram, and average pore diameter between 3.0 and 7.0 nm. Elemental analysis by means of energy dispersive X-ray spectroscopy of the preferred catalyst of Formula 1 indicates that the weight 15 ratio Fe:Al is in the range from 100:20 to 100:30. X-Ray Diffraction (XRD) indicates that the preferred catalyst of Formula 1 has average crystal size of 1.5 to 3 nm. The experimental results reported below indicate that the use 20of a pure copper-free Al-substituted spinel phase, i.e., the compound of Formula 1, in a nano-sized form, results in an increase in the CO 2 conversion and also in a better reaction selectivity towards the heavier, liquid hydrocarbons (designated . The spinel component, after activation and 25 self-organization at CO 2 hydrogenation conditions, is highly active and capable of supporting the conversion of carbon dioxide at an appreciable extent to higher hydrocarbons C+. When the hydrogenation of CO 2 is carried out in the presence of a spinel catalyst containing a hematite component, its 30 activity is lower due to the formation of a large amount of carbon deposits blocking the active phases. This is a result of oxidation of Fe-carbide phases formed during hematite carburization at the activation step by reactions with CO 2 and water formed in the process: 9 3 Fe 5

C

2 + 3CO 2 = C + 2CO +5 Fe 3 04 3Fe 5

C

2 + 20H 2 0 = 5Fe 3

O

4 + 20H 2 + 6C 5 Conversely, the hematite phase alone, which transforms at the activation step to carbides FeZC2 and Fe 7 C3, is capable of producing the desired high olefins/paraffins, but is not sufficiently active to permit acceptable CO 2 conversion. However, a catalyst which consists of pure K-promoted spinel 10phase, i.e., the catalyst of Formula 1, particularly when subjected to specific activation conditions and employed in a continuous process running through a set of successively arranged reactors, namely, a cascade of reactors, demonstrates an excellent activity. The high activity is 15 amounting to depressing of the formation of carbon deposits and stabilization of active carbide phases in a modified spinel matrix. This modified spinel matrix has less Fe content reduced at activation and in situ self-organization of the parent spinel phase due to partial removal of Fe-ions 20 forming carbide phases FeZC2 and Fe 7 C3. It appears that the presence of copper [i.e., in the spinel of Formula 2: (Cu 2 +xFe 2 +1-x) (Fe3+yAl 3 +1-y) 2041 facilitates reduction of iron ions during activation and at CO 2 hydrogenation conditions. We have found that copper is redundant when the activation is 25 accomplished by means of carburization. It should be noted that the catalyst of the invention can be processed to form pellets. To this end, the powdery material collected following the precipitation and separation of the 30 spinel of Formula 1 Fe2+(Fe3+yAl3+1-y)204 from its mother liquor is combined with a binder such as aluminum hydroxide (bohemite) powder and water to form a workable slurry. For example, the weight ratio Fe2+(Fe3+yAl3+1-y)204:alumina:water is from 1:0.14-0.71:0.43-0.86 . The mixture is extruded and the 10 so-formed extrudates are loaded with potassium, e.g., by means of the aforementioned impregnation with potassium carbonate solution, followed by drying and calcination. Another way to form pellets from the spinel of Formula 1 5 Fe2+(Fe3+yAl3+1-y)204 is by means of pressurizing the calcined powder after insertion of potassium using special form that yield cylindrical or empty cylindrical pellets. In use, the catalyst of the invention is loaded into a 10 suitable reactor, e.g., a continuous fixed bed reactor, or into a plurality of consecutively arranged reactors, as described in more detail below. The catalyst may be applied either in a powder or granular form. For example, the particle size of the catalyst used may be in the range from 15 100 pm to 3 mm. Thus, the powdery catalyst collected following the calcination step may be granulated, milled and then passed through a suitable sieve in order to collect the desired population of particles. The catalyst may also be applied in the form of pellets. The thickness of the catalyst 20 layer packed in the reactor may vary within the range of 7 mm to 3 m provided the particle size is selected so as to avoid excessive pressure drop. In order to be operative in the carbon dioxide hydrogenation 2 5process, the catalyst needs first to undergo activation. The activation of the catalyst is carried out in-situ, by either reduction (hydrogenation) or carburization. Reduction involves the flow of hydrogen stream through the 30reactor in which the catalyst is placed at a temperature of not less than 4000C. The flow rate of the hydrogen stream is not less than 100 cm 3 /min per gram of catalyst. The reduction is continued at atmospheric pressure for not less than 3 hours. After that the temperature is adjusted in hydrogen 11 flow according to the process conditions and a C0 2

/H

2 mixture is fed to the reactor. Carburization involves the exposure of the catalyst to a 5 carbon-containing atmosphere. To this end, streams of carbon monoxide, hydrogen and an inert gas carrier are caused to flow through the reactor in which the catalyst is placed at a temperature of not less than 3000C. The flow rates of the three gaseous components (CO, H2 and inert gas (N2, He, Ar)) 10are at least 30:30:150 cm 3 /min per one gram of the catalyst, respectively. The carburization is continued at atmospheric pressure for not less than 3 hours. The experimental results reported below indicate that the 15 mode of catalyst activation is of significance. The reduction leads to the transformation of the iron ions in spinel phase into the metallic iron that is subsequently converted to a mixture of Fe304 inactive in Fischer-Tropsh reaction and catalytically active FeCx carbide phases. Activation by 20means of carburization is preferred since it converts iron ions existing in the spinel phase in the starting catalyst directly to iron carbide phases of higher dispersion (particles of 20-35 nm) leaving the Fe-impoverished spinel phase as aggregates of nanoparticles of higher dispersion (8 25 10 nm) randomly mixed with iron carbide nanoparticles (Figure 1b). After hydrogen reduction and stabilization at reaction conditions the nanoparticles of carbide and spinel phases are larger (50 - 100 nm) and separated from each other by carbon that decreased the contact interface between carbide and 30 spinel phases (Figure la). Typical X-ray diffraction patterns of the fresh, activated (carburization) and stabilized at C0 2

/H

2 hydrogenation conditions catalyst of the present invention are presented in 12 Figure 2. The fresh catalyst consists of spinel phase of Formula 1 of high dispersion with crystal size of 1.5 to 3 nm, e.g., around 2 nm. After activation by carburization and stabilization in C0 2

/H

2 hydrogenation at 3000C for 100-150 h, 5 e.g., 120 h, the spinel phase is converted to Fe-carbide phases with crystal size of 25 and 45 nm while the crystal size of the spinel phase increases to 8.5 nm with decreasing the y value in its formula Fe(FeyAl-y)204 from 0.47 to 0.25. It means that part of the iron in the spinel phase during 10 activation-stabilization is converted to carbides. It is believed that the activity of the catalysts of the invention resides in the combination of the catalytic action of two phases - spinel catalyzing presumably the reverse water gas shift reaction producing CO, and iron carbides catalyzing 15 both reverse water gas shift and Fischer-Tropsch reaction that converts CO/H 2 to hydrocarbons. The effect of hematite phase content that may exist in the catalyst together with the substituted spinel phase at 20 different amounts depending on the synthesis conditions is clearly illustrated in Figure 3, which compares the CO 2 conversions and liquid hydrocarbon oil productivities measured in testing examples of the present invention and comparative examples at standard conditions. As shown in 25 Figure 3, the content of hematite phase in copper-free catalysts was in the range from 0 (pure spinel) to 100% (pure Fe-oxides) . The catalyst containing pure spinel without Fe oxide phase demonstrated the most efficient combination of catalytic activity and selectivity to C6+ hydrocarbons 30 reflected by highest productivity of C6+ hydrocarbons. The pure Fe-oxide phase without Al-, mixed Fe-Al-0-spinel - Fe203 materials or Cu-Al containing spinel promoted with potassium after activation display much lower activity in C02 13 hydrogenation to hydrocarbons than the catalyst consisting of pure Fe-Al-O spinel phase. Accordingly, another aspect of the invention is a process for 5 the preparation of hydrocarbons comprising the hydrogenation of carbon dioxide-containing gas in the presence of iron containing catalyst devoid of hematite phase, said catalyst being copper-free, wherein the catalyst is activated in-situ by means of carburization, said carburization comprises 10 treating said catalyst with a mixture of H2 and CO at elevated temperature. Following carburization, the content of the carbide phases in the catalyst is less than 15 wt%, preferably from 5 to 10 wt%, relative to the total weight of the catalyst. 15 Following the in-situ activation of the catalyst, the carbon dioxide hydrogenation reaction is allowed to start. Carbon dioxide-containing gaseous stream and hydrogen stream are continuously fed to the reactor at H 2

/CO

2 of not less than 2 20 and weight hourly space velocity (WHSV) not less than 0.1 h-1, preferably not less than 0.5 and more preferably not less than 1. The reaction is carried out at a temperature in the range from 250 to 3600C (for example, in the range from 320 to 3600C, especially 3250C to 3500C) at pressure of not less 25 than 5 atmospheres, e.g., from 10 to 30 or at a pressure higher than 20 atmospheres, e.g., in the range from 20 to 50, especially 20-40. It should be noted that the carbon dioxide-containing gas 30 stream used in the present invention may be neat carbon dioxide and also any gas mixture which contains carbon dioxide, for example, a mixture of carbon dioxide and carbon monoxide, with the molar fraction of carbon dioxide being not less than 0.25, more specifically not less than 0.5.

14 The reactants are preferably employed in the following molar ratios: For a feed consisting of hydrogen and carbon dioxide, the hydrogen to CO 2 molar ratio is less than 4:1 (e.g., not more than 3:1, for example, from 3:1 to 2:1); for a feed consisting of hydrogen, carbon dioxide and carbon monoxide, the hydrogen to (3CO 2 +2CO) molar ratio is 1, e.g., <1, for example, from 0.6 to 1, e.g., from 0.6 to 0.97. 10 The present invention therefore provides a process for the preparation of hydrocarbons, comprising the hydrogenation of carbon dioxide-containing gas in the presence of the catalyst of Formula 1, wherein the catalyst is activated in-situ by 15 means of carburization, said carburization comprises treating said catalyst with a mixture of H2 and CO at elevated temperatures, wherein following said carburization, the hydrogenation reaction takes place at a total pressure of not less than 20 bar at a temperature higher than 3201C, wherein 20hydrogen and carbon dioxide are fed at a molar ratio of not more than 3 or, hydrogen, 3CO 2 and 2CO are fed at a molar ratio of not more than unity. As already noted above, it has been found that it is 25 advantageous to conduct the catalytic hydrogenation of carbon dioxide-containing gaseous stream via a cascade process, namely, by using a plurality of fixed bed reactors arranged is series. The chief advantage offered by the cascade process of the invention resides in that it allows the 30introduction of intermediary step of water removal between each pair of serially-connected reactors. It has been found that water, which is a co-product of the reaction, has a double negative effect on the catalysts performance. First, the partial pressure of the water, which increases along the 15 catalyst bed from inlet to outlet, inhibits the reverse water-gas shift reaction: CO2 + H2 - CO+H 2 0, thus it limits the CO 2 conversion. Second, at high partial pressure of water the active carbide Fe5C2 phase is oxidized to iron oxide that 5 deactivates the catalyst. As a result, C02 conversion in one reactor reaches a limited value, well below 100%. (the experimental results reported below indicate that conversion measured at 300'C, WHSV <1 h-1 and total pressure of 10 atm asymptotically approaches ~ 60%). 10 Accordingly, one aspect of the invention relates to a cascade process for hydrogenation of carbon dioxide-containing gaseous stream employing a plurality of serially arranged reactors, comprising: 15 (i) feeding carbon dioxide-containing gas stream and hydrogen stream into at least the first of said serially arranged reactors which are loaded with iron-containing catalyst, said catalyst being copper-free, wherein said catalyst was brought to an active form by means of carburization; 20 (ii) discharging a gaseous reaction stream from at least one of said serially arranged reactors and cooling same, to form a liquid-gas mixture, wherein the liquid component of said mixture comprises condensable reaction products consisting of water and organic liquids, and the gas component of said 25 mixture comprises reactants and non-condensable reaction products; (iii) removing said gaseous component from said liquid component; (iv) separating said liquid component into an organic and 30 aqueous phases, and collecting at least said organic phase; (iv) directing the removed gaseous component into the successive reactor in said serially arranged reactors.

16 A suitable apparatus for carrying out the process of the invention is schematically illustrated in Figure 4, in which the cascade configuration consists of three serially arranged reactors. 5 The serially-positioned reactors are designated by numerals (1), (2) and (3) . Each reactor is provided with a suitable amount of a catalyst loaded therein. The amount of catalyst in each reactor is adjusted to improve conversion and productivity. Alternatively, the total amount of the catalyst 10used in the process may be equally divided between the set of reactors. Each reactor is provided with a discharge line (4), with a cooler (5), a gas-liquid separator (6) and a liquid-liquid 15 separator (7) positioned successively along said discharge line. Each liquid-liquid separator (7) is connected to two tanks, (8) and (9), for collecting organic and aqueous phases, respectively. The gas-liquid separator is connected by means of a feed line (10) into the consecutive reactor. 20 Carbon dioxide, hydrogen and optionally carbon monoxide required for the process are supplied through feed lines (11), (12) and (13), respectively. Hydrogen may be produced by the electrolysis of water in an electrolysis unit (not 25 shown) and carbon dioxide may be recovered from industrial processes such as the combustion of fossil fuels in power generating plants, cement or steel plants. Another useful source of the reactans required for the process is carbon dioxide-rich syngas, i.e., a gas mixture comprising C0 2 , H2 30 and CO where the concentration of C02 is greater than the normal concentration in conventional syngas, i.e., the molar fraction of carbon dioxide in the syngas is not less than 0.25 and preferably not less than 0.5.

17 In the specific embodiments shown in Figure 4, separate C0 2 , H2 and CO feeds are shown, equipped with flow controllers (14), and the gases are combined in a feed line (15) and introduced into the first reactor. While the description that 5 follows relates to the embodiment illustrated in Figure 4, it should be noted that a combined gaseous stream, e.g., carbon dioxide-rich syngas, may be utilized. In operation, carbon dioxide (11) and hydrogen (12), and 10optionally carbon monoxide (13) streams are fed to the first of said serially arranged reactors, with their relative amounts being adjusted by means of flow controllers (14). As shown in Figure 4, hydrogen may be directly fed also to each of the successive reactors by means of feed lines (15, 16) 15 equipped with flow controllers (14), so as to maintain an optimal ratio between the gaseous reactants. For example, C02, H2 and CO may be fed at molar ratios 1:5:1. The temperature and pressure maintained within each of the 20 serially-placed reactors are as set forth above, and the preferred WHSV, when using the copper-free catalyst of the invention, i.e., of Formula 1, is not less than 0.5. The gaseous mixture produced at each reactor is discharged 25 (4), and subjected to cooling and condensation (5) whereby a liquid-gas mixture is obtained. This mixture is separated into its liquid and gaseous components in a gas-liquid separator (6) . The gaseous, non-condensable component, which consists of 30non-reacted C02, H2 and CO with light organic compounds is removed from the liquid component and fed directly to the next reactor via line (10) . The liquid component is fed to a liquid-liquid separator (7), where it is separated into organic and aqueous phases, which are collected in two 18 distinct tanks. The organic product (8) (containing mainly alkanes and alkenes with 6-20 carbon atoms in their molecules) is further processed to produce high-quality liquid fuels by methods known in the art. As shown in Figure 5 4, a further separation may be conducted after the third stage, to separate liquids from non-condensable products. Notably, the cascade configuration illustrated in Figure 4 removes the limitations on CO 2 conversion rendered by high 10water partial pressure in the downstream parts of the catalysts layer in one fixed-bed reactor and allows reaching C02 conversions of > 75% and up to > 90%. Implementation of the reactors cascade arrangement according 15 to the present invention, with water removal between each pair of succssive reactors, allows to get higher C02 conversions and oil productivities in comparison to operting with the same catalyst but in a single reactor. This improvement is obtained irrespective of the type of catalyst 20used (either pure Fe-oxide or spinel or mixed catalysts) and composition. Implementation of cascade reactors configuration according to the present invention removes the limitation of ~ 60% C02 conversion that appears to be the upper limit when using Fe-based catalysts in a single reactor. This allows 25 reaching >90% C02 conversion at WHSV > 1 h-1. The present invention permits obtaining the liquid hydrocarbon oil as an excellent feedstock for production of transportation fuels: gasoline, jet fuel and diesel fuel 30 according to well established technologies [A.de Klerk, Energy Environ. Sci., 2011, 4, 1177]. The oil productivity at similar total WHSV obtained in three reactors in series increases by about factor of 3 and reaches 170-520 gram of oil per kilogram of catalyst per hour. This corresponds to 19 the productivity of about 0.5 million ton oil /year of the unit with 100 ton catalysts loading. The catalysts according to the present invention tested in a cascade reactors arrangement demonstrated excellent stability in 500 hour on 5 stream runs. A typical chromatogram of the liquid oil produced by the hydrogenation process of the invention indicates that the oil consists of hydrocarbons with 6 to 27 carbon atoms where 10distribution maximum is centered at 10-12 carbon atoms. As shown in the bar diagram of Figure 5, the hydrocarbon compositions of the liquid products formed in each of the three consecutive reactors are comparable (in each set of adjacent bars, the left, middle and right bars correspond to 15 the first, second and third reactors placed in series) The oil contains about 60 wt% of n-olefins and n-paraffins at weight ratio of 5:1, about 1 wt% aromatics, 0.1-0.2 wt% oxygenates and the rest - iso- olefins and iso-paraffins at weight ratio of 4:1. The water fraction separated from oil 20 contains 2-5 wt% of total organic carbon in form of light oxygenates. Distillation patterns demonstrate that the organic liquid obtained in C02 hydrogenation according to the present 25 invention can be separated by distillation to gasoline, jet and/or diesel fuels fractions according to technical needs. These fractions may be further upgraded to fit the fuels specification requirements by means of methods known in the art, e.g., as it is done for hydrocarbon products obtained in 30 a regular CO/H 2 Fischer-Tropsch process [A.de Klerk, supra].

20 In the drawings: 5 Figure 1 shows the multicomponent elements distribution maps of K/Fe-Al-0-spinel catalyst obtained by HRTEM/EELS: (1) after hydrogen reduction and stabilization in C02 hydrogenation at 300'C for 120 h; (2) - after carburization and stabilization in CO 2 hydrogenation at 3000C for 120 h. 10 Figure 2 shows XRD patterns of K/Fe-Al-0-spinel catalyst: (1) - fresh; (2) - after activation by carburization; (3) after stabilization in C02 hydrogenation at 3000C for 120 h. 15 Figure 3 demonstrates the effect of the content of Fe203 (Hematite) phase in the mixed Fe203-Fe-Al-0-spinel catalyst on the catalysts performance in CO 2 hydrogenation. Testing conditions: T = 3000C, Ptotai = 10 atm, H 2

/CO

2 = 4. 20Figure 4 illustrates a scheme of an apparatus based on a cascade reactors system useful for CO 2 hydrogenation. (1), (2) and (3) serially-positioned reactors; (4) discharge line; (5) cooler; (6) gas-liquid separator; (7) liquid-liquid separator; (8) organic collector; (9) aqueous phases 25 collector; (10) feed line into the consecutive reactor; (11), (12) and (13) carbon dioxide, hydrogen and carbon monoxide feed lines, respectively; (14) flow controllers; (15), (16) gas feed lines. 30Figure 5 is a bar diagram illustrating the contents of paraffins, olefins, aromatics and oxygenates in the hydrocarbon oil obtained after one, two and three reactors in series.

21 Examples Methods X-Ray Diffraction (XRD) The X-ray diffraction (XRD) patterns 5 were obtained with a Phillips 1050/70 powder diffractometer fitted with a graphite monochromator, at 40 kV and 28 mA. Software developed by Crystal Logic was used. The data were collected in a range of 20 values between 50 and 800 with a step size of 0.050. Phase identification was performed by 10using BEDE ZDS computer search/match program coupled with the ICDD (International Center for Diffraction Data) Powder Diffraction File database (2006) . The average crystal size of Fe304, Fe 2 + (Fe 3 +yAl 3 +1-y)204 spinel, Fe203, FeZC2 and Fe 7 C3 phases was determined from the Scherrer equation h = KA/ [ (B 2 _ 2) 0.5 15 cos(20/2)], where K = 1.000 is the shape factor, A = 0.154 nm, is the instrumental broadening correction, and B is the reflection broadening at corresponding 20. The average crystal size was obtained by averaging of the data calculated for reflections (110), (200); (220), (311); (220), (311), (440); 20 (020) , (112); (102), (211) and (110), (200) of the XRD patterns corresponding to the Hematite Fe203 phase (ICDD Card 86-550), Magnetite Fe304 (ICDD Card 19-629), Cu-Al-Fe-0 spinels (ICDD Cards 34-192, 77-10), Hdgg carbide FeZC2 (ICDD Card 36-1248), carbide Fe 7 C3(ICDD Card 17-333) and metallic af 25 Fe (ICDD Card 6-696) phases, respectively. The relative content of Fe-oxides, carbide phases and amorphous carbon phase represented in X-ray diffractograms by a wide reflection centered at 2e = 22- was obtained by Rietveld refinement of the XRD profile by using the DBWS-9807 program. 30 The composition of spinel phases nanoparticles in prepared catalytic materials was derived from XRD data - by fitting the measured parameters of the unit cell of cubic Fe304-phase to the contents of Cu 2 + and Al 3 + ions at tetrahedral and 22 octahedral positions, respectively, in the cubic framework of spinel phase with space group Fd3m. The parameters of unit cells of spinel phases were calculated based on the positions of reflections detected in X-ray diffractograms around 20 5 =300 (220), 35.50 (311) and 630 (440). Surface area and pore volume measurements Surface area and pore volume were derived from N2 adsorption desorption isotherms using conventional BET and BJH methods (Barrett-Joyner-Halenda method, Journal of American Chemical 10 Society, 73, 373, 1951). The samples were degassed under vacuum at 250-70'C, depending on their thermal stability. Isotherms were measured at liquid nitrogen temperature with a NOVA-2000 Quantachrome, Version 7.02 instrument. Energy dispersive X-ray spectroscopy (EDAX) 15 The total elemental composition of catalysts was measured by EDAX method using Quanta-200, SEM-EDAX, FEI Co. instrument. The contents of Cu 2 + and Al 3 + ions in spinel nanoparticles were confirmed by the data of local EDAX method recorded with the electronic spot diameter of 5 nm with the field emission 2 0analytical transmission electron microscope (JEOL JEM-2100F) operated at accelerating voltage of 200 kV. The nanoparticles of spinel phases were identified by recording the multicomponent distribution maps for nanoparticles observed at HRTEM images. 25 High resolution TEM / electron energy loss spectroscopy (HRTEM/EELS) The transmission electron microscope (JEOL JEM-2100F) used for materials analysis was equipped with a Gatan imaging filter (GIF Quantum) / EELS system. Regular and energy 30 filtered images were taken from the same samples point for Fe, 0 and C elements at L-edge 708 eV; K-edge 532 eV and K edge 284 eV, respectively. The obtained elemental distributions maps were further combined in one RGB image marking Fe by red, C by green and 0 by blue colors. This 23 yielded multicomponent elements distribution maps for nanoparticles observed in regular HRTEM images. Gatan Digital Micrograph software was used for EFTEM imaging, recording and processing of EELS data. The samples for HRTEM were prepared 5 by depositing a drop of ethanol suspension of the solid catalyst on a silica-coated copper grid that formed a contrast oxide background for carbon-rich particles. Example 1 (comparative) 10 Preparation of a catalyst consisting of hematite phase [Fe203] and spinel phase of the formula [ (Cu 2 +xFe 2 +1-x) (Fe 3 +yAl 3 +1-y) 204; (x=0 .54, y=0.65)] The catalyst was prepared by co-precipitation from the aqueous solution of Fe, Cu and Al nitrates by addition of 15 aqueous ammonium hydroxide solution. 21.0 gram of Al(N03)3-9H20, 72.3 gram of Fe(NO3)3-9H20 and 6.8 gram of Cu(N03)2-3H20 salts were dissolved in 20 , 20 and 4 cm 3 of distilled water, respectively. All three solutions were then mixed together, and 500 cm 3 of 3% NH40H solution were 2 0gradually added to this mixed salts solution at room temperature under stirring during a period of 10 min. The pH of solution after the addition of NH40H was 6.8. A solid precipitated from the solution. The solid was separated by filtration and washed on the filter with 500 cm 3 of distilled 2 5 water. Then the solid was dried in air at 1100C for period of 24 h. The obtained material was impregnated by incipient wetness with aqueous solution containing 1.04 gram K 2

CO

3 . The impregnated material was dried in air at 110'C for period of 48 h and calcined in air at 450'C for period of 6 h 30 (temperature increasing rate 5 0 C/min) . The material has the following weight ratio of metal components (EDAX): Fe:Al:K:Cu = 100:15:6:5, surface area 100 m 2 /g, pore volume 0.17 cm 3 /g and average pore diameter 4.3 nm. The material 24 contained two phases (XRD) : 30 wt% of hematite Fe203 and 70 wt% of phase with spinel structure which composition reflects partial isomorphous substitution of Fe 2 + ions with Cu 2 +, and Fe 3 + ions with Al 3 + ions, such that the spinel phase of the 5 catalyst has the formula: (Cu 2 +xFe 2 +1-x) (Fe 3 +yAl 3 +1-y) 2041 where x = 0 .54 and y = 0 .65. Example 2 (comparative) Preparation of a catalyst consisting of spinel phase only 10 [ (cu2+xFe 2+1-x) (Fe 3+yAl3+1-y) 204; (x=0 .72, y=0 .71) ] The catalyst was prepared according to procedure described in Example 1. However, in the present example the adjustment of pH value to 6.8 was achieved by adding 200 cm 3 of aqueous

NH

4 0H solution with concentration of ammonium hydroxide of 15 10%. The fast basification caused the inclusion of more Cu and Fe ions in (Cu 2 +xFe2+1-x) (Fe 3 +yAl 3 +1-y) 204 spinel phase with x = 0.72 and y = 0.71. Correspondingly, no Fe203 hematite phase was formed after calcination at 450'C. The material had the following weight ratio of metal components (EDAX): Fe:Al:K:Cu 20= 100:15:5:6, surface area 138 m 2 /gram, pore volume 0.20 cm 3 /gram and average pore diameter 4.3 nm. Example 3 (comparative) Preparation of a catalyst consisting of 25 hematite phase [Fe203] and spinel phase of the formula [Fe2+ (Fe 3 +yAl 3 +1-y) 204] ; (y=0 .40) ] The catalyst was prepared according to the procedure described in Example 1 but without any addition of Cu(N03)2 salt to the mixed solution of metal nitrates. The material 30has following weight ratio of metal components (EDAX): Fe:Al:K = 100:15:6, surface area 107 m 2 /gram, pore volume 0.20 cm 3 /gram and average pore diameter 3.4 nm. The material contained two phases (XRD): 41 wt% of hematite Fe203 and 59 25 wt% of phase with spinel structure which composition reflects partial isomorphous substitution of Fe 3 + ions with Al 3 + ions, such that the spinel phase of the catalyst is represented by the following formula: 5 [Fe2+(Fe3+yAl3+1-y)204] where y= 0.40. Example 4 Preparation of a catalyst consisting of hematite phase [Fe203] and spinel phase of the formula 10 [Fe2+ (Fe 3 +yAl 3 +1-y) 204] (y=0. 64) ] The catalyst was prepared according to the procedure described in Example 1, but without any addition of Cu(N03)2-3H20 salt to the mixed solution of metal nitrates. In this example 94 gram of Fe(NO3)3-9H20 salt was used for 15 preparation of iron salt solution in 50 cm 3 water and for adjustment of the pH value to 6.8, 535 cm 3 of 3% NH 4 0H aqueous solution were added to the metal salt solution. The resultant material has the following weight ratio of metal components (EDAX) : Fe:Al:K = 100:12:5, surface area 113 m 2 /gram, pore 2 0volume 0.21 cm 3 /gram and average pore diameter 4.9 nm. The material contained two phases (XRD): 45 wt% of hematite Fe203 and 55 wt% of phase with spinel structure whose composition reflects partial isomorphous substitution of Fe 3 + ions with Al 3 + ions, such that the spinel phase of the catalyst is 25 represented by the formula: [Fe2+(Fe3+yAl3+1-y)204] where y = 0.64. Example 5 (comparative) Preparation of a catalyst consisting of hematite phase [Fe203] 30 and spinel phase of the formula [Fe2+ (Fe3+yAl 3 +1-y)204] (y=0.70)] The catalyst was prepared according to the procedure described in Example 1 but without the addition of Cu(N03)2-3H20 salt to the mixed solution of metal nitrates. In 26 this example 115.7 gram of Fe(NO3)3-9H20 salt was used for preparation of iron salt solution in 62 cm 3 of water and for the adjustment of the pH value to 6.8 was added 570 cm 3 of 3%

NH

4 0H aqueous solution. The material obtained has the 5 following weight ratio of metal components (EDAX): Fe:Al:K = 100:9:4, surface area 93 m 2 /gram, pore volume 0.21 cm 3 /gram and average pore diameter 6.5 nm. The material contained two phases (XRD) : 86 wt% of hematite Fe203 and 14 wt% of phase with spinel structure whose composition reflects isomorphous 10 substitution of Fe 3 + ions with Al 3 + ions, such that the spinel phase of the catalyst is represented by the formula [Fe2+(Fe3+yAl3+1-y)204] where y = 0.70. Example 6 (comparative) 15 Preparation of a catalyst consisting of iron oxide phases [Fe203; Fe304] The procedure is according to US 5,140,049. Iron Oxide catalyst was obtained by combustion synthesis 2 0using glycolic acid as organic complexant. 12.6 gram of Glycolic acid were dissolved in 10% aqueous ammonia up to pH 6.5 and slowly added to a solution containing 67 gram of Fe(N03)3 - 9 H20 dissolved in 50 cm 3 of water. Then the water, ammonia and part of NO3 ions converted to NO/NO2 were removed 25 from the mixed solution in rotavapor increasing the temperature from 40 to 800C up to complete drying of the material. The dried precipitate was calcined in air at 3500C for 1 h (heating rate 50C min-) . The formed iron oxide was impregnated by incipient wetness method with aqueous K 2

CO

3 30 solution, followed by drying in air at 1100C overnight. The material consisted on 35 wt% Hematite Fe203 and 65 wt% Magnetite Fe304. It had surface area of 110 m 2 /gram, pore volume 0.31 cm 3 /gram and average pore diameter 4.3 nm.

27 Example 7 (of the invention) Preparation of a catalyst consisting of copper-free spinel phase only [Fe(Fe+yAl3+1-y)204; (y=0.47)] The catalyst was prepared by co-precipitation from the 5 aqueous solution of Fe and Al nitrates by gradual addition of aqueous ammonium hydroxide solution. 27.0 gram of Al(NO3)3-9H20 and 57.9 gram of Fe(NO3)3-9H20 were dissolved in 60 cm 3 of distilled water each. The solutions were then mixed together and the pH value was adjusted to 8.0 by gradually 10 adding 250 cm 3 of aqueous NH40H solution with concentration of ammonium hydroxide of 5 wt%. The addition time was 15 minutes. The precipitate was recovered and impregnated with

K

2

CO

3 solution as described in Example 1. In the present example the atomic ratio of Fe:Al in the precipitating 15 solution was 2:1. Correspondingly, no Fe203 hematite phase was formed after calcination at 450'C. The material had the following weight ratio of metal components (EDAX): Fe:Al:K = 100:24:6, surface area 128 m 2 /gram, pore volume 0.53 cm 3 /gram and average pore diameter 3.5 nm. 20 Example 8 (of the invention) Preparation of a catalyst consisting of copper-free spinel phase only [Fe(Fe3+yAl3+1-y) 204; (y=0. 31) ] The catalyst was prepared by co-precipitation from the 25 aqueous solution of Fe and Al nitrates by addition of aqueous ammonium hydroxide solution as described in Example 7. After mixing the aqueous solutions of Fe- and Al-salts the pH value was adjusted to 8.5 by gradually adding 265 cm 3 of an aqueous

NH

4 0H solution (with concentration of 5 wt%) . The addition 30time was 15 minutes. The precipitate was recovered and impregnated with K 2

CO

3 solution as described in Example 1. The material consisted of only one - Al-substituted Fe304 spinel phase of formula Fe (Fe 3 +o.31Al 3 +o.69)204 and had following weight ratio of metal components (EDAX) : Fe:Al:K = 100:42:6, surface 28 area 118 m 2 /gram, pore volume 0.43 cm 3 /gram and average pore diameter 3.0 nm. Example 9 (of the invention) 5 Preparation of a catalyst consisting of copper-free spinel phase only [Fe(Fe 3 +yAl 3 +1-y)204; (y=0.71)] The catalyst was prepared by co-precipitation from the aqueous solution of Fe and Al nitrates by addition of aqueous ammonium hydroxide solution as described in Example 7. After 10mixing the aqueous solutions of Fe- and Al-salts the pH value was adjusted to 7.2 by gradually adding 100 cm 3 of aqueous

NH

4 0H solution with concentration of ammonium hydroxide of 5 wt%. The addition time was 15 minutes and the precipitate was recovered and impregnated with K 2

CO

3 solution as described in 15 Example 1. The material consisted of only one - Al substituted Fe304 spinel phase of formula Fe (Fe 3 +o.

7 nAl 3 +o.29) 204 and had following weight ratio of metal components (EDAX): Fe:Al:K = 100:12:6, surface area 103 m 2 /gram, pore volume 0.38 cm 3 /gram and average pore diameter 3.7 nm. 20 Example 10 (comparative) Preparation of a catalyst consisting on iron, copper and potassium deposited on A1 2 0 3 support (According to WO 97/05088, WO 01/34538 Al, US 4,555,526). 25 To 36 gram of Fe(N03)3-9H20, 1.25 gram of Cu(N03)2 .3H20 and 3 gram of K 2 CO3 dissolved in 100 cm 3 of distilled water was added 20 gram of a powder of y-A1203 with surface area of 180 m 2 /gram. The mixture was vigorously stirred and heated at 800C to evaporate water. After evaporation of water, the solid 30reaction mixture was dried at 1200C in air for 24 hours and calcined at 4500C for 6 hours. The obtained catalyst had following weight ratio of metal components (EDAX): Fe:Cu:Al:K = 100:6:21:0.34, surface area 76 m 2 /gram, pore volume 0.16 cm 3 /gram and average pore diameter 8.2 nm.

29 The compositions of the catalysts of Examples 1 to 10 are tabulated in Table A. Table A catalyst Hematite phase Spinel phase Fe 2 0 3 (Cu 2 +xFe2+1x-) (Fe3+yAl 3 +-y) 204 1 30% wt% 70% wt% comparative x=0.54, y=0.65 2 0% 100 wt% comparative x=0.72, y=0.71 3 41% (wt%) 59% (wt%) comparative x=0.00, y=0.40 4 45% (wt%) 55% (wt%) comparative x=0.00, y=0.64 5 86% (wt%) 14% (wt%) comparative x=0.00, y=0.70 6 20% (wt%) comparative Fe 3 0 4 80% (wt%) 7 0% 100 wt% of the invention x= 0.0; y = 0.47 8 0% 100 wt% of the invention x = 0.0; y = 0.31 9 0% 100 wt% of the invention x = 0.0; y = 0.71 10 Fe-Cu-K/A1203 comparative In the next set of examples (Examples 11-22), the catalysts 5 of Examples 1-10 were tested for their activity and selectivity in C02 hydrogenation reaction to form fuel compositions. Catalysts testing included catalyst activation, reaction and products analysis. 10 Catalysts activation was done by means of two methods: reduction in hydrogen at 100 cm 3 /min*gramcat, temperature 450'C, atmospheric pressure for 24 h; and carburization in a mixture of carbon monoxide and hydrogen in helium at flows 30:30:140 cm 3 /min*gramcat respectively, at temperature 300'C, 15 atmospheric pressure for 3 h.

CO

2 hydrogenation reaction was conducted by passing a mixture of H2 and C02 flows at ratio 4:1 through the 3 gram of catalyst mixed with 1.8 gram of inert silica packed in a 20 tubular reactor (11 mm ID and 210 mm long, 45 mm catalytic phase) and heated up to 300'C or 320 0 C at the total pressure 30 of 10 atm. The reaction products were cooled down to +4'C and separated in cooled (+4'C) container. Gas products were analyzed in online Agilent 7890A Series Gas Chromatograph equipped with 7 columns and 5 automatic valves using helium 5 as a carrier gas. Liquid products were separated into aqueous and organic phases. Aqueous phase was analyzed for Total Organic Carbon in Shimadzu TOC-VCPN Analyzer. The liquid organic phase composition was analyzed by Agilent 190915-433 Gas Chromatograph combined with Mass Spectrometer in the 10range M/Z= 33-500, equipped with 5973 mass selective detector, HP-5MS column (30 m, 250 pm, i.d. 0.25 pm) and helium as a carrier gas. The distillation patterns of hydrocarbon oil were estimated by simulated distillation method based on the maximal boiling points of components in 15 10 vol% oil fractions. The oil productivity was calculated based on the weighted amounts of organic liquid (Woii) collected over a specific period of time on stream: OP = Woii /Wcat/RT gram/gram catalyst/h, where Wcat is weight of catalyst (gram) loaded to reactor, RT -time period on stream (hours). 20 The selectivity to CO, CH 4 , C2-C5 and C6+ hydrocarbons was calculated on the carbon basis as Si = [Ci / (Cco2*Xco2) ] * 100%, where Ci amount of carbon (gram) contained in product (i) produced at period of time, Cco2 - amount of carbon (gram) contained in C02 passed the reactor at the same period of 2 5 time, XCo2 - CO 2 conversion. In the tables below, the following abbreviations are used: Con for conversion, Sel for selectivity and Pro for productivity. 30 Example 11 Carbon dioxide hydrogenation in one fixed bed reactor The Catalyst of Example 1 was packed in a fixed bed reactor and activated by H2 reduction as described above. The effect of WHSV on the reaction products was determined. The results 31 are shown in Table 1. Increasing of the space time by decreasing of WHSV of C02 did not increase the CO 2 conversion beyond 60%. Table 1

C

2 -CE C 6 ± oil

CO

2

CO

2 Methane CO WHSV Con., Sel. Sel. h-1 % % % Sel. Pro. Sel. Pro. % (g/gczth).102 % (g/gteh).102 2 36 9 13 44 11.3 25 6.4 1 46 9 9 42 6.3 29 4.3 0.5 52 9 7 46 4.3 30 2.8 0.2 59 9 5 44 1.9 35 1.5 0.1 60 9 4 35 0.7 29 0.6 5 Example 12 Carbon dioxide hydrogenation in one fixed bed reactor The catalyst of Example 1 was packed in a fixed bed reactor 10 and activated by carburization as described above. The effect of WHSV upon the reaction products was determined. The results are shown in Table 2. Comparison of the results presented in Tables 1 and 2 indicates a significantly higher activity of the catalyst after carburization compared with 15 its activation by hydrogen reduction. Higher CO 2 conversions and oil productivities were measured at different WHSV with carburized catalyst. Table 2 C2-C,9 C 6 ± oil

CO

2

CO

2 Methane CO WHSV Con., Sel. Sel. h-1 % % % Sel. Pro. Sel. Pro. % (g/gcazth).102 % (g/geateh).102 6 40 10 12 38 32.2 29 24.6 3 46 11 7 41 20.1 26 12.5 1 53 8 5 15 10.9 19 3.5 32 Reaction conditions: Temperature 300'C, Total pressure 10 atm, H 2

/CO

2 = 4 mol/mol. Example 13 5 Carbon dioxide hydrogenation in one fixed bed reactor Catalyst prepared as described in Example 3 was packed in a fixed bed reactor and activated by carburization as described above. The effects of WHSV on the reaction products were determined. The results are shown in Table 3. 10 Table 3

C

2

-C

3

C

6 ± oil

CO

2

CO

2 Methane CO WHSV Con., Sel. Sel. Sel. Pro. Sel. Pro. % (g/gcavth).102 % (g/geateh).102 1 52 9 10 45 8.3 25 4.7 6 41 10 20 44 36.3 15 12.3 Reaction conditions: Temperature 300'C, Total pressure 10 atm, H 2 /C0 2 =4. 15 Example 14 Carbon dioxide hydrogenation in one fixed bed reactor Catalyst prepared as described in Example 4 was packed in a fixed bed reactor and activated by carburization as described above. Effects of WHSV upon the reaction products were 20determined. The results are shown in Table 4. Table 4 C2-C,9 C 6 ± oil

CO

2

CO

2 Methane CO WHSV Con., Sel. Sel. Sel. Pro. Sel. Pro. % (g/gcavth).102 % (g/geateh).102 1 53 9 6 46 8.5 24 4.5 6 33 6 31 41 27.4 15 9.8 33 Reaction conditions: T = 3000C, P=10 atm, H 2 /C0 2 =4. Example 15 Carbon dioxide hydrogenation in one fixed bed reactor 5 Catalyst prepared as described in Example 5 was packed in a fixed bed reactor and activated by carburization as described above. The effects of WHSV on the reaction products were determined. The results are shown in Table 5. Table 5

CO

2

CO

2 Methane CO C 2-

C

3

C

6 ± oil WHSV Con., Sel. Sel. h-1 % % % Sel. Pro. Sel. Pro. % (g/gcteh) .102 % (g/getaeh) .102 1 37 8 14 50 6.6 20 3.5 6 20 7 83 1 0.2 3 1.0 10 Reaction conditions: T=300'C, P=10 atm, H 2 /C0 2 =4. Example 16 Carbon dioxide hydrogenation in one fixed bed reactor in the 15 presence of a catalyst consisting of spinel phase only (Cu-free) Catalyst prepared as described in Example 7 was packed in a fixed bed reactor and activated by carburization as described above. The effect of WHSV upon the reaction products was 20 determined. The results are shown in Table 6. Table 6

C

2 -CE C 6 ± oil

CO

2

CO

2 Methane CO WHSV Con., Sel. Sel. h-1 % % % Sel. Pro. Sel. Pro. % (g/gcazth) .102 % (g/geteh) .102 1 52 12 6 39 7.9 29 5.8 6 45 12 13 27 26 40 38.5 34 Reaction conditions: T = 3000C, Total pressure 10 atm,

H

2 /C0 2 =4. The selectivities to C6+ hydrocarbons and oil productivity 5 obtained with this catalyst of the present invention are significantly higher compared to that measured with carburized K/FeOx or biphasic K/Cu-Fe-Al-O-Fe2O3, K/Fe-Al-0 Fe203 catalysts. 10 Example 17 Carbon dioxide hydrogenation in one fixed bed reactor in the presence of a catalyst consisting of spinel phase only (containing Cu) Catalyst prepared as described in Example 2 was packed in a 15 fixed bed reactor and activated by H2. The effect of WHSV upon the reaction products was determined. The results are shown in Table 7. Table 7

C

2

-C

3

C

6 ± oil

CO

2

CO

2 Methane CO WHSV Con., Sel. Sel. h-1 % % % Sel. Pro. Sel. Pro. % (g/geateh).102 % (g/geateh) .10 2 1 35 9 28 39 4.9 16 2.0 6 23 8 39 46 22.6 6 2.9 20 Reaction conditions: T = 3000C, Total pressure 10 atm,

H

2 /C0 2 =4.

35 Example 18 Testing in one fixed bed reactor of a catalyst consisting of iron oxide phases [Fe203; Fe304] and not containing spinel 5 phase The catalyst prepared according to Example 6 was packed in the tubular reactor and activated by carburization as described above. The testing results are shown in Table 8. 10 Table 8

C

2

-C

3

C

6 ± oil

CO

2 Methane CO Con., Sel. Sel. Sel. Pro. Sel. Pro. % (g/gcazth) .102 % (g/geteh) .102 39 8 16 46 5.9 21 2.7 Reaction conditions: 300 0 C, 10 atm, H 2 /CO2=4, WHSV=1.0 h-1 Example 19 15 Carbon dioxide hydrogenation in one fixed bed reactor The catalyst prepared according to Example 9 was packed in the tubular reactor and activated by hydrogen reduction as described above. The testing results are shown in Table 9. Table 9

C

2 -CE C 6 ± oil

CO

2 Methane CO Con., Sel. Sel. Sel. Pro. Sel. Pro. % (g/gcazth) .102 % (g/geteh) .102 27 10 28 48 4.6 11 1.1 20 Reaction conditions: Temperature 300 0 C, total pressure 10 atm, H 2

/CO

2 =4, WHSV= 1 h-1.

36 Example 20 Carbon dioxide hydrogenation in one fixed bed reactor The catalyst prepared according to Example 8 was packed in 5 the tubular reactor and activated by carburization as described above. The testing results are shown in Table 10. Table 10

C

2

-C

3

C

6 ± oil

CO

2

CO

2 Methane CO WHSV Con., Sel. Sel. h-1 % % % Sel. Pro. Sel. Pro. % (g/gcazth).102 % (g/geateh).102 1 52 13 6 41 7.6 27 5.0 10 Reaction conditions: Temperature 300 0 C, total pressure 10 atm, H 2

/CO

2 =4, WHSV= 1 h-1. Example 21 Carbon dioxide hydrogenation in one fixed bed reactor 15 The catalyst prepared according to Example 9 was packed in the tubular reactor and activated by carburization as described above. The testing results are shown in Table 11. Table 11

C

2 -CE C 6 ± oil

CO

2

CO

2 Methane CO WHSV Con., Sel. Sel. h-1 % % % Sel. Pro. Sel. Pro. % (g/gcazth).102 % (g/geateh).102 1 53 13 7 40 7.6 28 5.3 20 Reaction conditions: Temperature 300 0 C, total pressure 10 atm, H 2

/CO

2 =4, WHSV= 1 h-1.

37 Example 22 Carbon dioxide hydrogenation in one fixed bed reactor The catalyst prepared according to Example 10 was packed in the tubular reactor and activated by hydrogen reduction as 5 described above. The testing results are shown in Table 12. Table 12

C

2

-C

3

C

6 ± oil

CO

2 Methane CO Con., Sel. Sel. Sel. Pro. Sel. Pro. % (g/gcavth).102 % (g/geateh).102 38 8 15 58 7.9 8.6 1.2 Reaction conditions: Temperature 300'C, total pressure 10 atm, H 2

/CO

2 =4, WHSV= 1 h-1. 10

CO

2 conversion levels achieved by the catalysts of Examples 1-10, when operating under the following set of experimental conditions: Temperature 300'C, total pressure 10 atm,

H

2

/CO

2 =4, WHSVCO2= 1 h-1, as reported in Examples 11-22, are 15 tabulated in Table B. Table B catalyst C02 conversion % 1 53 2 35 3 52 4 53 5 37 6 39 7 52 8 52 9 53 10 40 In the next set of examples (Examples 23-27), some of the catalysts demonstrating CO 2 conversion of slightly more than 20 50% according to the data tabulated in Table B (i.e., the catalysts of Examples 1, 3, 4 and 7) were tested in an experimental set-up consisting of three reactors positioned in series, with water removal taking place between each pair 38 of consecutive reactors, i.e., between the first and second reactors, and between the second and third reactors. Example 23 5 Carbon dioxide hydrogenation in three reactors in series 6 gram of the catalyst prepared as described in Example 1 was packed in three fixed bed reactors in series. 2 gram of catalyst was packed in each reactor and activated by carburization as described above. The testing system 10consisted of 3 consecutive SS fixed bed reactors with pressure, temperature and flow controls (shown in Figure 4). After each reactor the heavy organic products (oil) and water were condensed in a cooling system and collected in the tank. After separation of liquid products, the gases containing 15 non-reacted C0 2 , H2 and light Hydrocarbons, C 1 -C5 proceeded to flow to the next reactor. After each reactor the gas and liquid products were analyzed as described above. All the three reactors were kept at the same temperature and total pressure of 10 atm. 20 The catalyst performance as a function of temperature, H 2 :CO2 molar ratio and the number of reactors (N) in the testing system is listed in Table 13. Table 13

C

2

-C

3

C

6 ± oil T CO2 CO 2

CH

4 CO N OC H2: CO2 WHSV Con. Sel. Sel. h-I % % % Sel. Pro. Sel. Pro. % (g/gcazth).102 % (g/geateh).102 1 300 4:1 6 40 12 11 35 26.6 31 23.2 2 300 4:1 3 62 12 5 40 23.4 33 19.3 3 300 4:1 2 77 12 2 42 34.2 34 17.6 3 320 3:1 2 72 9 3 32 37.8 38 18.1 3 320 4:1 2 90 12 1 44 34.0 34 19.0 3 320 6:1 2 93 18 1 47 26.7 27 16.2 39 Example 24 Carbon dioxide hydrogenation in three reactors in series 6 gram of catalyst prepared as described in Example 3 was packed in three fixed bed reactors in series as set out in 5 Example 23. The aqueous and liquid hydrocarbons phases were separated from light gases between first and second and between second and third reactors as shown in Figure 4. The catalyst in all three reactors was activated by carburization as described above and tested as in Example 23. The effects 10 of temperature and total pressure upon the reaction products were determined. The results are shown in Table 14. The oil hydrocarbon composition was similar to that obtained for oil collected in Example 23. 15 Table 14

C

2 -CE C 6 ± oil T, P, CO2' CO 2

CH

4 CO N 0 C atm WHSV Con. Sel. Sel. h-1 % % % Sel. Pro. Sel. Pro. % (g/gcazth).102 % (g/geateh).102 1 300 10 6 41 10 20 44 36.3 15 12.3 3 300 10 2 79 10 4 42 21.8 33 17 3 320 10 2 84 11 2 38 21.2 37 20.7 3 320 15 2 86 12 2 30 16.6 43 24.0 3 320 5 2 62 9 30 40 16.7 16 6.9 Reaction conditions: H 2 /C0 2 =4. Example 25 20 Carbon dioxide hydrogenation in three reactors in series 6 gram of catalyst prepared as described in Example 6 was packed in three fixed bed reactors in series as set out in Example 23. The catalyst was activated by carburization as described above and tested as in Example 23. The effect of 25 WHSV upon the reaction products was determined. The results 40 are shown in Table 15. The oil hydrocarbon composition was similar to that obtained for oil collected in Example 23. Table 15

C

2 -CE C 6 ± oil CO2'

CO

2

CH

4 CO N WHSV Con. Sel. Sel. h-1 % % % Sel. Pro. Sel. Pro. % (g/gczth) .102 % (g/get h) .102 3 1 70 10 10 34 7.8 28 6.5 3 2 57 8 20 39 14.0 26 10.6 5 Reaction conditions: T= 3000C, H 2 /C0 2 =4, total pressure 10 atm. Example 26 Carbon dioxide hydrogenation in three reactors in series in 10 the presence of a catalyst consisting of spinel phase only (Cu-free catalyst) 6 gram of catalyst prepared as described in Example 7 was packed in three fixed bed reactors in series as set out in Example 23. The aqueous and liquid hydrocarbons phases were 15 separated from light gases between first and second and between second and third reactors as shown in the scheme of Figure 4. The catalyst in all three reactors was activated by carburization as described above and tested as in Example 23. The effects of WHSVCO2 upon the reaction products were 20determined. The results are shown in Table 16. The cascade reactors configuration with this catalyst of the present invention gives maximal C6+ hydrocarbons selectivity and oil productivity about 0.5 kg/kgct h. 25 41 Table 16

C

2 -C C 6 ± oil T, P, CO2' CO 2

CH

4 CO N 0 C atm WHSV Con. Sel. Sel. h-1 % % % Sel. Pro. Sel. Pro. % (g/gcazth).10 2 % (g/geateh).10 2 1 320 10 2 54 10 11 36 12.3 32 10.9 3 320 10 2 89 13 4 30 18.8 47 29.6 3 320 10 6 81 15 7 35 44.9 38 59.2 Reaction conditions: T = 3200C, Total pressure 10 atm,

H

2 /C0 2 =4. 5 Example 27 Carbon dioxide/Carbon monoxide hydrogenation in three reactors in series 6 gram of catalyst prepared as described in Example 7 was 10packed in three fixed bed reactors in series with pressure, temperature and flow controls as set out in Example 23. 2 gram of the catalyst was packed in each reactor and activated by carburization as described above. The catalyst was tested in hydrogenation reaction of the mixture of C02 and CO by 15 feeding a mixture of H2, C02 and CO flows at molar ratio 5:1:1, respectively. After each reactor the heavy organic products (oil) and water were condensed in a cooling system and collected in the tank. After separation of liquid products, the gases containing non-reacted C02, CO and H2 and 20 light hydrocarbons flowed to the next reactor. The gas products were analyzed as described above after the third reactor. The liquids were collected from three reactors were mixed and analyzed as described above. All the three reactors were kept at the same temperature and total pressure. The oil 25 productivity was calculated based on the weighted amounts of organic liquid (Woii) collected per hour: OP = Woii/Wcat/h, where Wcat is total weight of loaded catalyst. The selectivity 42 to CH 4 , C 2 -C5 and C6+ hydrocarbons was calculated on the carbon basis as Si = [Ci / (Cc02+co*XTotai) ] * 100%, where Ci amount of carbon (gram) contained in product (i) produced at period of time, Cco2+co - amount of carbon (gram) contained in 5 both CO 2 and CO that flowed through the reactor at the same period of time, XTotai - total conversion of C calculated as Creacted/Cin (weight fraction) . The effect of pressure upon the reaction products was determined. The results are shown in Table 17. 10 Table 17

C

2 -CE C 6 ± oil

CO

2 CO CO 2 +CO P CO 2 CO CH 4 Total WHSV WHSV WHSV atm Con Con Sel Con% h-1 h-1 h-1 % % % gel Pro. Se Pro. % (g/gcazth) % (g/gcazth) .102 .102 1.0 0.6 1.6 10 55 97 13.4 73.2 52.4 22.1 29 12.3 1.0 0.6 1.6 15 66 98 14.1 80.0 50 23.1 30 13.9 Reaction conditions: T= 320 0 C, H 2 /C0 2 /CO=5:1:1. Example 28 15 Carbon dioxide hydrogenation in three reactors in series with different catalysts at CO 2 conversion of 75% adjusted by varying of WHSVco 2 In the set of experiments described in this Example, the performance (activity and selectivity) of the catalysts 20 tabulated in Table B was measured under identical conditions (the same feed composition, temperature, pressure and C02 conversion). The latter variable is controlled by varying the space velocity. Using the three packed-bed-reactors-in-series system illustrated in Figure 4, high CO 2 conversion (75%) was 25 reached to reflect the selectivity to hydrocarbons. Thus, 6 gram of catalysts prepared as described in Examples 1, 3, 4, 6, 7, 8 and 9 were packed in separate experiments in 43 three fixed bed reactors in series as set out in Example 23. The catalysts were activated by carburization as described above. The results set out in Table 18 were measured for every catalyst after 200 h of run at 3000C, P = 10 atm, H 2 /CO2 5 = 4 and properly adjusted WHSVCO2 to produce total C02 conversion of 75%. Table 18 Catalyst WHSVCo 2 Products selectivity, wt% h-1 CH 4 CO C2-C4 C2-C4 C2-C4 C5+ C5+ pro. Olefins paraffins Oxygenates g/gcashe10-2 in water 1 2.0 12 2 29 8 7 41 20.3 3 1.5 10 3 30 10 9 38 15.2 4 1.5 11 4 29 9 8 37 14.8 6 1.0 10 9 29 8 8 35 8.2 7 6.0 16 3 28 8 7 38 54.8 8 5.0 14 3 29 9 7 38 50.8 9 4.0 15 4 28 8 8 37 40.6 10 The results shown in Table 18 demonstrate that the catalysts consisting of pure phase of Al-substituted Fe304 with spinel structure, i.e., the catalysts represented by Formula 1 Fe2+ (Fe3+yAl3+1-y) 204; (y=0.05 - 0.95, preferably y=0.25 - 0.75 and more preferably y=0.30 - 0.70), i.e., catalysts of 15 Examples 7, 8 and 9, display higher catalytic activity in conversion of C02 to hydrocarbons compared with the catalysts of Examples 1, 3, 4 and 6. Example 29 20 Preparation of extruded catalyst consisting of spinel phase only [Fe (Fe 3 +yAl 3 +1-y)204; (x=0.00, y=0.47)] Fe (Fe 3 +yAl 3 +1-y )20 4 from Example 7 was formed as extrudates with cylindrical shape using A1203 as a binder. 11.73 gram of Fe (Fe3+yAl 3 +1_-y)204 prepared in Example 7 was mixed with 4.89 2 5gram of A100H powder (Disperal P2, Sasol Ltd., Germany) and water was added to get a slurry. The slurry was kneeded in a mortar and extruded using a matrix with 1.2 mm cylindrical 44 shape opening. The extrudates were dried at room temperature for 24 h, then at 110'C overnight and calcined at 450'C for period of 2 h (temperature increasing rate 5 0 C/min) . The so formed material was impregnated by incipient wetness with 5 aqueous solution containing 2.15 gram K 2

CO

3 . The impregnated material was dried in air at 110'C for period of 24 h and calcined in air at 450'C for period of 2 h (temperature increasing rate 5 0 C/min). 10 Example 30 Preparation of a catalyst K/Fe2+ (Fe 3 +yAl 3 +1-y) 204 (y=0 .47) in the form of binder-free granules The powder product of Example 7 was loaded into a round 15 template with inner diameter of 4 cm. A load of 20 tons was applied twice on the sample. The so-formed binder-free pellet was crushed and a faction consisting of granules with size in the range from 1.4 to 1.7 mm was collected by sieving. 20 Example 31 Carbon dioxide hydrogenation in three reactors in series 15 gram of the catalyst of Example 30 in the form of pellets with sizes in the range of 1.4 - 1.7 mm were packed in three 25 16mm ID and 300mm long fixed bed reactors equipped with 2.3mm ID thermowells and arranged in series as illustrated in Figure 4. Each reactor contained 5 gram of catalyst diluted with 15 gram of silica. The total pressure at the inlet was 30 atm and pressure drop in the system of less than 0.5 atm. 30 The feedstock consisted of H2 and CO 2 at a molar ratio of 2.9 and WHSV of C02 was 0.7. The temperature profile in each reactor is given in Table 19. The performance is set out in Table 20.

45 Table 19 First Second Third Position in the reactor (cm) reactor reactor reactor Temperature 0 326 324 323 1 334 325 325 2 338 325 325 3 336 326 323 4 330 325 322 5 327 324 321 6 325 323 320 7 324 322 319 8 322 320 317 Table 20

XC

0 2 XH2 SC5+ SC7+ SMethane SEthylene SCO SC3-C 4 SC2-C 4 Soxygenates olefins paraffins 76.6 84.7 57.9 53.9 8.8 4.1 1.6 13.4 5.2 9.1 5 Example 32 Carbon dioxide/Carbon monoxide hydrogenation in three reactors in series 10 3 grams of the catalyst of Example 7 in a powder form were packed in three 11mm ID and 150mm long fixed bed reactors equipped with 2.3mm ID thermowells and arranged in series as illustrated in Figure 4. Each reactor contained 1 gram of 15 catalyst diluted with 3 gram of silica. The total inlet pressure was 20 atm and pressure drop in the system of less than 0.5 atm, the feedstock consisted of C02, CO and H2 at a molar ratio of 1:1:4.8 and WHSV of CO 2 and CO combined of 2h 1. The temperature profile in each reactor is given in Table 2021. The performance is set out in Table 22. 25 46 Table 21 First Second Third Position in the reactor (cm) reactor reactor reactor Temperature 0 306 313 312 0.5 312 322 319 1.0 315 330 325 1.5 318 332 327 2.0 322 333 328 2.5 324 331 327 3.0 327 329 325 3.5 329 324 320 Table 22

XC

0 2 XH2 SC5+ SC7+ SMethane SEthylee SCO SC3-C4 SC2-C Soxygenates COolefins paraffims 41.8 95.5 75.2 50.6 46.0 11.5 4.1 4.0 16.7 9.7 7.2 5 Example 33 Carbon dioxide/Carbon monoxide hydrogenation in three reactors in series 10 3 grams of the catalyst of Example 7 in a powder form were packed in three 11mm ID and 150mm long fixed bed reactors equipped with 2.3mm ID thermowells and arranged in series as illustrated in Figure 4. Each reactor contained 1 gram of catalyst diluted with 3 gram of silica. The total inlet 15 pressure was 20 atm and pressure drop in the system of less than 0.5 atm, the feedstock consisted of C02, CO and H2 at a molar ratio of 1:0.7:4.1 and WHSV of C02 and CO combined of 0.9h-1. The temperature profile in each reactor is given in Table 23. The performance is set out in Table 24. 20 25 47 Table 23 First Second Third Position in the reactor (cm) reactor reactor reactor Temperature 0 308 321 321 0.5 313 328 328 1.0 317 334 333 1.5 320 338 335 2.0 322 339 336 2.5 323 339 336 3.0 324 338 334 3.5 324 334 331 Table 24

XC

0 2 XH 2 SC5+ SC 7 ± SMethane SEthylee SCO SC3-C4 SC2-4 Soxygenates COolefins paraffims 56.3 95.9 81.8 62.4 59.7 8.8 1.7 1.8 10.3 10.6 6.1 5 In compliance with the statute, the invention has been described in language more or less specific to structural or methodical features. The term "comprises" and its variations, 10 such as "comprising" and "comprised of" is used throughout in an inclusive sense and not to the exclusion of any additional features. It is to be understood that the invention is not limited to specific features shown or described since the means herein described comprises preferred forms of putting 15 the invention into effect. The invention is, therefore, claimed in any of its forms or modifications within the proper scope of the appended claims appropriately interpreted by those skilled in the art. 20 Throughout the specification and claims (if present), unless the context requires otherwise, the term "substantially" or "about" will be understood to not be limited to the value for the range qualified by the terms.

48 Any embodiment of the invention is meant to be illustrative only and is not meant to be limiting to the invention. Therefore, it should be appreciated that various other 5 changes and modifications can be made to any embodiment described without departing from the spirit and scope of the invention. Features, integers, characteristics, compounds, chemical 10moieties or groups described in conjunction with a particular aspect, embodiment or example of the invention are to be understood to be applicable to any other aspect, embodiment or example described herein unless incompatible therewith. 15

Claims (1)

1. 5. 51 13) A cascade process for the hydrogenation of carbon-dioxide containing gas, employing a plurality of serially arranged reactors, comprising: (i) feeding carbon dioxide-containing gas and hydrogen 5 streams into at least the first of said serially arranged reactors which are loaded with iron-containing catalyst, said catalyst being copper-free, wherein said catalyst was brought to an active form by means of carburization; (ii) discharging a gaseous reaction stream from at least one 10 of said serially arranged reactors and cooling same, to form a gas-liquid mixture, wherein the liquid component of said mixture comprises condensable reaction products consisting of water and organic liquids, and the gas component of said mixture comprises reactants and non-condensable reaction 15 products; (iii) separating said gaseous component from said liquid component; (iv) separating said liquid component into an organic and aqueous phases, and collecting at least said organic phase; 20 and (v) feeding the gaseous component into the successive reactor in said serially arranged reactors. 14) A process according to claim 13, wherein the catalyst 25 loaded in said reactors is as defined in any one of claims 1 to 5.