Catalytic compositions useful in removal of sulfur compounds from gaseous hydrocarbons, processes for making these and uses thereof

Abstract

A catalytic composition is disclosed, which exhibits an X-ray amorphous oxide, with a spinel formula and highly dispersed crystals of ZnO, CuO, and optionally CeO.sub.2. The composition is useful in oxidative and adsorptive processes for removing sulfur from gaseous hydrocarbons.

Claims

1. A method for removing a portion of sulfur contained in a hydrocarbon, comprising contacting said sulfur containing hydrocarbon in gaseous form to a catalytic composition comprising copper oxide in an amount ranging from 20 weight percent (wt %) to 45 wt %, zinc oxide in an amount ranging from 12 wt % to less than 20 wt %, CeO.sub.2 in the form of particles ranging in diameter from 5 nm to 10 nm, in an amount ranging from 0.1 wt % to 10 wt % and aluminum oxide in an amount ranging from 20 wt % to 40 wt %, wherein said catalytic composition has an X-ray amorphous oxide phase, and a formula Cu.sub.xZn.sub.1-xAl.sub.2O.sub.4 wherein x ranges from 0 to 1, highly dispersed crystalline ZnO and CuO, said contacting occurring in the presence of pure oxygen at a gas hourly space velocity (GHSV) of from 1,000 to 20,000 h.sup.1, said catalytic composition prepared by: (i) combining an aqueous solution containing each of copper nitrate, zinc nitrate, and aluminum nitrate with an alkaline solution containing NaOH and/or at least one of (NH.sub.4).sub.2CO.sub.3, Na.sub.2CO.sub.3 and NH.sub.4HCO.sub.3, at a temperature of from about 50 C. to about 65 C., and a pH of from about 6.5 to about 14, to form a precipitate containing at least one of (a) a carbonate containing Cu, Zn, and Al, (b) a hydroxide containing Cu, Zn, and Al, and (c) a hydroxycarbonate containing Cu, Zn, and Al; (ii) aging said precipitate; (iii) filtering and washing said precipitate; (iv) drying said precipitate for at least 10 hours, at a temperature of at least 100 C.; and (v) combining the precipitate with a binder selected from the group consisting of poly-ethylene oxide, polyvinyl alcohol, a sol of aluminum pseudoboehmite, silica gel and mixtures thereof, said binder being added in amount ranging from 1 to 10 weight % of said precipitate, to from an extrudable mixture, extruding said mixture through a die to form an extrudate drying said extrudate for 24 hours at room temperature, followed by drying said extrudate at 100 C. for from 2-4 hours, and raising temperature to 500 C., at a rate of from 2-5 C./minute, to calcine said extrudate for from 2-4 hours.

2. The method of claim 1, comprising oxidizing sulfur in said sulfur containing hydrocarbon.

3. The method of claim 1, comprising adsorbing a sulfur containing compound into said catalyst.

4. The method of claim 1, further comprising regenerating said catalyst.

5. The method of claim 1, wherein said catalytic composition is in granular form.

6. The method of claim 5, wherein pores of granules have a diameter of from 8 nm to 12 nm.

7. The method of claim 6, wherein pores of the granules of said composition have a volume of from about 0.1 cm.sup.3/g to about 0.5 cm.sup.3/g.

8. The method of claim 6, wherein said pores of said catalytic composition have a diameter of from 8 nm to 10 nm.

9. The method of claim 1, wherein said catalytic composition is formed as a cylinder, a sphere, a trilobe, or a quatrolobe.

10. The method of claim 5, wherein said catalytic composition is in the form of granules having a diameter of from 1 mm to 4 mm.

11. The method of claim 1, wherein said catalytic composition has a specific surface area of from 10 m.sup.2/g to 100 m.sup.2/g.

12. The method of claim 11, wherein said catalytic composition has a specific surface area of from 50 m.sup.2/g to 100 m.sup.2/g.

13. The method of claim 1, wherein X is from 0.1 to 0.6.

14. The method of claim 13, wherein X is from 0.2 to 0.5.

15. The method of claim 1, wherein said GHSV is from 5,000 h.sup.1 to 15,000 h.sup.1.

16. The method of claim 15, wherein said GHSV is from 5,000 h.sup.1 to 10,000 h.sup.1.

17. The method of claim 1, wherein said GHSV is 1,000 h.sup.1 or more and less than 3,000 h.sup.1.

Description

BRIEF DESCRIPTION OF THE FIGURES

(1) FIG. 1 shows one reactor system useful in the practice of the invention.

(2) FIG. 2 depicts graphically, the loss in activity of the catalysts of the invention due to adsorption of sulfur containing compounds thereon.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Example 1

(3) Cu(NO.sub.3).sub.2, (0.2 moles), Zn(NO.sub.3).sub.2 (0.07 moles), and Al(NO.sub.3).sub.3 (0.235 moles), were dissolved in 500 ml of distilled water, to form what shall be referred to as solution A hereafter. The pH of the solution was 2.3.

(4) Similarly, 19.08 g of Na.sub.2CO.sub.3, (0.18 moles), and 36 g of NaOH (0.9 moles), were dissolved in 600 ml of distilled water, to produce solution B, which had a pH of 13.7.

(5) Solution A was heated to 65 C. and solution B was added to solution A, at a rate of about 5 ml/minute, with constant agitation, until all of solution B was added. The resulting mixture had a pH of 11.0. A precipitate resulted which was aged, for 6 hours, at 65 C., pH 11. The solution was cooled to room temperature and filtered with a Buchner funnel. Precipitate was washed with distilled water. Analysis showed that nearly all of the Cu, Zn, and Al precipitated out of the solution (99%).

(6) The precipitate was then dried at room temperature, for 12 hours, at 110 C. The dried material was dark brown in color. Following drying, it was calcined, at 500 C., for 2 hours.

(7) The calcined product contained 36 wt % elemental Cu, 12.1 wt % elemental Zn, 14.2 wt % elemental Al, and 0.02 wt % elemental Na. (In all of the examples which follow, weight percent is given in terms of the pure element, rather than the oxide.)

(8) Referring now to FIG. 1, alternate embodiments of the invention may be seen therein. In either embodiment a feedstock stream 1 and a feed of an oxidizing agent 2 are combined, one of reactors 10a or 10b, which are, respectively, oxidation and adsorption reactors. When the stream is sent to reactor 10a for the oxidation reaction to take place, gas stream 4 is removed and transferred to high pressure separation reactor 20, where C.sub.1-C.sub.4 gases, oxygen, any SO.sub.2, H.sub.2S and COS are separated, as is sulfur free steam 9, which is removed from the reactor.

(9) The stream containing the other materials 5, is then sent to a scrubber reactor 30, where SO.sub.2 and H.sub.2S are removed, with the remaining, cleaned gas sent for oxidation, while sulfur containing materials are treated to obtain pure sulfur.

(10) If materials are sent to adsorptive reactor 10b, as noted supra, any of sulfites, sulfates, and sulfides deposit on the catalyst, and the thus treated gas undergoes the same processes that the gas resulting from the oxidation reaction does.

(11) The atomic ratio of Cu:Zn:Al was 3:1:2.8. The product had a specific surface area of 94 m.sup.2/g, pore volume of 0.24 cm.sup.3/g, and an average pore diameter of 9.5 nm. It exhibited highly dispersed CuO and ZnO, with an X-ray amorphous oxide phase. X-ray amorphous oxide phase as used herein means that, when observed via high resolution transmission electron microscopy (HRTEM), crystalline particles ranging from 2-10 nm, and usually 2-5 nm, were observed. Lattice parameters were very close to those of spinels, hence the chemical composition, deduced from EDX data, is Cu.sub.0.3Zn.sub.0.7Al.sub.2O.sub.4.

Example 2

(12) A 500 ml sample of solution A was prepared as was 600 ml of a new solution B, which contained 1 mole of (NH.sub.4).sub.2CO.sub.3, at pH 8.7.

(13) Solution A was heated to 65 C., and solution B was added gradually to solution A, with constant agitation. The combined solution had a pH of 7.6.

(14) Following combination of solutions A and B, a precipitate formed, which was aged for 1 hour at 65 C. The precipitate was filtered in the same way the precipitate of Example 1 was filtered, and was then washed with room temperature distilled water. Analysis showed the precipitate contained about 99% of the Zn and Al from the solution and 80-85% of the Cu passed to the precipitate.

(15) Precipitate was dried, as in Example 1, supra, and then calcined at 500 C. for 4 hours.

(16) The resulting compound was 26.3 wt % Cu, 15.8 wt % Zn, 22.3 wt % Al, and the atomic ratio of Cu:Zn:Al was 1.7:1:3.5. The compound had a specific surface area of 82 m.sup.2/g, pore volume of 0.29 cm.sup.3/g, and an average pore diameter of 12 nm. It exhibited an X-ray amorphous oxide phase (Cu.sub.0.45Zn.sub.0.55Al.sub.2O.sub.4), and highly dispersed CuO, which contained less than 50% of the total copper.

Example 3

(17) As in the first 2 examples, a sample of solution A was prepared. In this Example, solution B was prepared by combining 47.7 g (0.45 moles) of Na.sub.2CO.sub.3, and 18 g (0.45 moles) of NaOH, in 600 ml of distilled water, to produce a solution with a pH of 13.4.

(18) Solution A was heated to 50 C., and solution B was added gradually, at a rate of 4 ml/min, with constant agitation. The resulting pH was 10.

(19) A precipitate formed and was aged for 2 hours at 50 C., pH 8.5, during which the solution was filtered. Following washing, the precipitate was analyzed and found to contain about 99% of the Cu, Zn, and Al of the amount initially contained in the solution, but it also contained a high amount of Na.

(20) Following drying at room temperature for 12 hours, and then for 12 hours at 110 C., the dark brown precipitate was calcined at 500 C., for 2 hours.

(21) The resulting product contained 40.5 wt % Cu, 13.3 wt % Zn, 13.8 wt % Al, and 0.47 wt % Na. The atomic ratio of the components Cu:Zn:Al was 3.1:1:2.5. The composition had a specific surface area of 62 m.sup.2/g, a pore volume of 0.15 cm.sup.3/g, and an average pore diameter of 8.7 nm. As with the preceding examples, the composition exhibited an X-ray amorphous oxide phase (Cu.sub.0.2Zn.sub.0.8Al.sub.2O.sub.4), and a highly dispersed crystal phase which contained most of the Cu.

Example 4

(22) The steps of Example 1 were followed, but the precipitate was filtered hot, and without aging. The calcined composition contained 40.2 wt % Cu, 9.7 wt % Zn, 17.2 wt % Al, and 0.22 wt % Na. The atomic ratio of Cu:Zn:Al was 4.2:1:4.3. The specific surface area was 75 m.sup.2/g, and the pore volume was 0.29 cm.sup.3/g. Average pore diameter was 12.5 nm. The phase composition was highly dispersed, crystalline phases of CuO, ZnO, and Al.sub.2O.sub.3.

Example 5

(23) In this example, Example 2 was followed except 5.510.sup.4 moles of cerium nitrate were added to solution A. After the precipitate was formed, it was aged for 6 hours at 55 C. Analysis of the calcined composition showed 20.9 wt % Cu, 17.1 wt % Zn, 23.9 wt % Al, and 0.5 wt % Ce. The atomic ratio of Cu:Zn:Ce:Al was 3.0:1:0.01:3.8. The composition had a specific area of 83 m.sup.2/g, a pore volume of 0.20 cm.sup.3/g, and an average pore diameter of 10.0 nm. It exhibited an X-ray amorphous oxide phase with a composition of Cu.sub.0.5Zn.sub.0.5Al.sub.2O.sub.4 and a highly dispersed crystalline phase of CuO, which contained less than 60% of the Cu, and also a cerium phase, with particles not exceeding 5 nm in diameter. While the amounts of oxides are not provided here or hereafter, the method set forth in Example 1, supra, can be followed to secure precise amounts thereof.

Example 6

(24) This example parallels Example 5, except the amount of cerium nitrate was increased to 9.510.sup.3 moles. Precipitation formation and filtration were carried out at 65 C., for 6 hours.

(25) The resulting calcined composition had the following composition: Cu: 20.2 wt %, Zn: 15.1 wt %, Al: 20.2 wt %, Ce: 8.5 wt %. Atomic ratios of Cu:Zn:Ce:Al were 1:35:1:0.25:3.2. The specific surface area was 125 m.sup.2/g, with a pore volume of 0.3 cm.sup.3/g. Average pore diameter was 8.0 nm. As with the other compositions, it exhibited an X-ray amorphous oxide phase and a formula of Cu.sub.0.5Zn.sub.0.5Al.sub.2O.sub.4. It also exhibited a cerium phase with particles not greater than 10 nm in diameter.

Example 7

(26) In this example, solution A contained 0.05 moles Cu nitrate, 0.07 moles Zn nitrate, and 0.13 moles Al nitrate, in 500 ml of distilled water, at a pH of 2.6.

(27) Solution B contained 53.0 g Na.sub.2CO.sub.3 (0.5 moles), and 18 g NaOH (0.45 moles), in 600 ml of water, at a pH of 13.7. The solutions were mixed and the resulting precipitate separated, as in Example 1. The calcined composition contained 10 wt % Cu, 20.0 wt % Zn, 21.3 wt % Al, and 0.65 wt % Na. The atomic ratio of Cu:Zn:Al was 0.5:1:2.5, with a specific surface area of 112 m.sup.2/g, a pore volume of 0.30 cm.sup.3/g, and average pore diameter of 10.8 nm. The composition exhibited formula Cu.sub.0.33Zn.sub.0.67Al.sub.2O.sub.4, and the composition also contained a highly dispersed crystalline ZnO phase.

Example 8

(28) In this example, solutions A and B were prepared in the same manner as the solutions of Example 2.

(29) Aging of the precipitate took place over 6 hours, at 65 C., pH 6.5, rather than 1 hour, as in Example 2.

(30) The resulting calcined product contained 10.0 wt % Cu, 12.1 wt % Zn, 33.8 wt % Al, and 0.05 wt % Na. The atomic ratio for Cu:Zn:Al was 0.84:1:6.7. The specific surface area was 100 m.sup.2/g, the pore volume 0.35 cm.sup.3/g, and the average pore diameter was 11.0 nm. The composition exhibited the same X-ray amorphous oxide phase formula Cu.sub.0.4Zn.sub.0.6Al.sub.2O.sub.4, and there was a -Al.sub.2O.sub.3 phase as well.

Example 9

(31) In this example, Solution A contained 0.05 moles Cu nitrate, 0.02 moles Zn nitrate, and 0.45 moles Al nitrate, dissolved in 500 ml distilled water, and have a pH of 2.25.

(32) Solution B contained 53.0 g (0.5 m) (NH.sub.4).sub.2CO.sub.3 dissolved in 600 ml of distilled water. The pH was 8.0.

(33) Precipitation, and separation of the precipitate, took place over 4 hours, at 65 C., pH 6.5, to yield a composition containing 13.0 wt % Cu, 4.2 wt % Zn, and 36.5 wt % Al. The atomic ratio for Cu:Zn:Al was 3.1:1:21. The specific surface area was 150 m.sup.2/g, with a pore volume of 0.45 cm.sup.3/g, with an average pore volume of 9.5 nm. The observed formula of the composition was ZnAl.sub.2O.sub.4 and Al.sub.2O.sub.3 modified by Cu in the form of CuO.

Example 10

(34) In this example, solution A contained 0.25 m Cu, 0.07 moles Zn, and 0.20 moles Al in their nitrate form, dissolved in 500 ml of distilled water, at pH 2.3. Solution B contained 53.0 g Na.sub.2CO.sub.3 (0.5 m), and 12 g NaOH (0.3 m), in 600 ml distilled water, at pH 13.3.

(35) Precipitation conditions were those of Example 1, supra, which did not permit total precipitation of Al. In fact, while the precipitation of Cu and Zn was 99% that of Al did not exceed 80%. The resulting composition contained 50 wt % Cu, 25.2 wt % Zn, 7.4 wt % Al, and 0.85 wt % Na. The atomic ratio of Cu:Zn:Al was 2.0:1.0:0.7. The specific surface area was 50 m.sup.2/g, the pore volume was 0.20 cm.sup.3/g, and the average pore diameter was 15.2 nm. The formula of the composition was Cu.sub.0.33Zn.sub.0.67Al.sub.2O.sub.4, with highly dispersed crystalline CuO and ZnO phases.

Example 11

(36) In this final synthesis example, solution A did not contain Al nitrate, but only 0.04 moles Cu, 0.02 moles Zn and 0.14 moles Ce in nitrate form, dissolved in 500 ml of distilled water, at pH 4.2.

(37) Solution B contained 15.0 g (NH.sub.4).sub.2CO.sub.3 and 18.0 g NH.sub.4HCO.sub.3 in 600 ml distilled water, at a pH of 8.0.

(38) Following calcination, the composition contained 6.5 wt % Cu, 3.85 wt % Zn, and 78 wt % Ce. The atomic ratio of components Cu:Zn:Ce was 1.7:1:9.5, and the specific surface area was 85 m.sup.2/g, with pore volume 0.23 cm.sup.3/g and average pore diameter of 10.9 nm. The observed composition by XRD was a highly dispersed crystalline CeO.sub.2 phase. Crystalline phases of Cu and Zn were not detected.

Example 12

(39) The catalysts prepared in Examples 1-11, supra, were then tested for their ability to oxidatively desulfurize fuel oil containing sulfur-containing compounds. Fuels were prepared which contained thiophene, DBT (dibenzothiophene), and 4,6 DMDBT. The fuels were heated to gaseous state, and passed over the catalytic compounds. In the Tables which follow, the formulation of the catalyst (CuZnAl, CuZnAlCe, or CuZnCe) is followed by (1) or (2). This refers to the nature of solution B in Examples 1-11, with (1) referring to a Na containing solution and (2) to an ammonium containing solution, as per Examples 1 and 2. The final number indicates which example was used to produce the catalyst.

Example 13

(40) Thiophene, DBT, and a diesel fuel with the following properties were oxidized: T.sub.50: 264; T.sub.95: 351; density at 20 C., in Kg/l: 0.841, sulfur, in wt %: 1.93, was oxidized with the catalyst of Example 1. Similarly, 4,6 DMDBT was oxidized with the catalysts of Examples 1, 2, and 5. Tables 4, 5, and 6 present these results:

(41) TABLE-US-00004 TABLE 4 Oxidation of thiophene in octane solution S Content GHSV WHSV S Removal HC Conversion Catalyst T C. ppmw O.sub.2/S h.sup.1 h.sup.1 W % W % CuZnAl (1)-1 329 1000 59 22500 28 90 1.2

(42) TABLE-US-00005 TABLE 5 Oxidation of DBT in toluene solution T S Content GHSV WHSV S removal HC Conversion Catalyst C. ppmw O.sub.2/S h.sup.1 h.sup.1 W % W % CuZnAl (1)-1 300 800 80 2600 6 87 2.1 CuZnAl (2)-2 360 900 139 2900 6 53 3.5 CuZnAl (1)-3 385 900 120 3700 8 69 3.9 CuZnAl(1)-4 370 900 95 3200 8 31 2.9 CuZnAlCe(2)-5 350 900 140 2900 6 55 3.1 CuZnAlCe(2)-6 400 900 140 3100 6 26 3.0 CuZnAl (1)-7 350 1100 100 1700 6 33 1.3 CuZnAl (1)-8 340 1000 120 3900 6 48 3.7 CuZnAl (1)-9 400 1500 40 27000 28 66 1.7 CuZnAl (1)-10 340 1100 60 1500 6 24 3.3 CuZnCe(2)-11 310 800 70 2600 6 22 1.9 CuZnCe(2)-11 330 4100 30 4100 6 14 4.2

(43) TABLE-US-00006 TABLE 6 Oxidation of 4,6-DMDBT in toluene solution T S Content GHSV WHSV Catalyst C. ppmw O.sub.2/S h.sup.1 h.sup.1 S Removal % HC Conversion % CuZnAl (1)-1 312 900 140 2085 6 81 3.8 CuZnAl (2)-2 350 1000 140 2100 6 78 3.5 CuZnAlCe(2)-5 350 1000 140 2100 6 37 4.1

(44) About 0.16 vol. % of H.sub.2S, 0.118 vol. % of SO.sub.2, and 5 vol. % of CO.sub.2 were found at the reactor outlet upon oxidation of the diesel fuel.

(45) In these tables, GHSV refers to the gas volume rate (in liters/hour), WHSV means weight hourly space velocity: feed rate (Kg/hours) over the weight of the catalyst. O.sub.2/S refers to the rate at which oxygen was introduced to the material being tested. S and HC refer to sulfur and hydrocarbon, respectively.

Example 14

(46) This, and the following examples, summarize experiments which show that sulfur can be removed from feedstreams via an adsorptive process.

(47) As with the prior examples, model hydrocarbon fuels containing thiophene, DBT, or 4,6DMDBT (both were dissolved in toluene at 0.09-0.5 wt. % S) were treated, using the catalysts of the examples, at various conditions, as set forth in Tables 7, 8, and 9 which follow:

(48) TABLE-US-00007 TABLE 7 Adsorptive/oxidative desulfurization of thiophene in hydrocarbon S conversion S conversion calculated calculated from S from gas- analysis of T, content, GHSV, WHSV, phase liquid HC Catalyst C. wt. % O.sub.2/S h.sup.1 h.sup.1 Time, h products, % products, % conversion, % CuZnAl (1) 317 0.1 59 20730 28 1 46 82 0.5 317 0.1 59 20730 28 6 40 40 1.5 CuZnAl (2) 300 0.5 12 9600 28 1 30 45 1.0 300 0.5 12 9600 28 6 24 16 3.1 *The hydrocarbon was octane for catalyst CuZnAl(1) and toluene for CuZnAl(2).

(49) TABLE-US-00008 TABLE 8 Adsorptive/oxidative desulfurization of DBT in toluene S conversion S conversion calculated calculated from S from gas- analysis of T, content, GHSV, WHSV, phase liquid HC Catalyst C. wt. % O.sub.2/S h.sup.1 h.sup.1 Time, h products, % products, % conversion, % CuZnAl (1) 300 0.16 50 2100 6 1 13 80 1.3 CuZnAl (2) 300 0.08 80 2600 6 1 18 87 2.1 300 0.08 80 2600 6 6 55 49 3.1 CuZnCeAl 400 0.09 140 3100 6 1 15 40 3.0 (3) 400 0.09 140 3100 6 6 29 26 3.0 CuZnAl (1) 300 0.46 20 2700 6 1 13 60 1.0 300 0.43 20 3260 6 4 38 47 2.0 300 0.46 20 2100 6 8 17 23 2.7

(50) TABLE-US-00009 TABLE 9 Adsorptive/oxidative desulfurization of 4,6-DMDBT in toluene S conversion S conversion calculated calculated from S from gas- analysis of T, content, GHSV, WHSV, phase liquid HC Catalyst C. wt. % O.sub.2/S, h.sup.1 h.sup.1 Time, h products, % products, % conversion, % CuZnAl (1) 370 0.09 138 3000 6 2 28 70 2.8 CuZnAl (1) 310 0.09 138 2084 6 2 36 81 3.8 310 0.09 138 2084 6 6 32 32 3.4 CuZnAl (1) 350 0.09 138 2084 6 4 52 78 3.6 350 0.09 138 2084 6 8 49 47 3.6

(51) Analysis showed that the sulfur removed in gas and liquid phases, differed. With respect to the gas phase, the prevailing sulfur containing compound was SO.sub.2, in amounts which varied from 0.035 vol. % to 0.42 vol. %. This value depended upon, inter alia, the sulfur content of the feedstream, the O.sub.2/S ratio, the GHSV value, and the length of the reaction. When lower values were seen in the gas phase, this was due to deposit of sulfites, sulfides, and sulfates in the catalysts. Indeed, examination of spent catalysts, via FTIR, showed superficial SO.sub.4.sup.2 groups, including CuSO.sub.4 and ZnSO.sub.4. Bulk sulfates were not observed. Tables 7, 8, and 9 summarize these data.

Example 15

(52) Over the course of the experiments described in Example 14, supra, catalytic activity decreased markedly. FIG. 2 presents exemplary data for a feedstream of thiophene in octane at a sulfur concentration of 0.14 wt. %, with sulfur being converted to gaseous SO.sub.2 and COS. The reaction took place over the time period indicated, and temperatures of the reaction (in C.) are given.

(53) As can be seen from the open circles, catalytic activity decreased over time after 5-6 hours it was necessary to reactivate the catalysts. The manner in which reactivation was accomplished is set forth in Examples 19 et seq.

Example 16

(54) Further experiments were carried out to study adsorption and oxidation in accordance with the invention.

(55) A commercially available diesel fuel marketed for off road applications was analyzed for sulfur content, using standard techniques. The total sulfur content was determined to be 0.042 wt. %, distributed, for the most part, amongst dibenzothiophene, 4-methyldibenzothiophene, 4,6-dimethyldibenzothiophene, acenaphthol[1,2-b]thiophene, 1,4,7,-trimethyldibenzothiophene, and 4-ethyl-6-bethyldibenzothiophene.

(56) Three different experiments using different parameters, were carried out. The results are summarized here:

(57) TABLE-US-00010 TABLE 10 Adsorptive/oxidative desulfurization of diesel fuel for off-road applications S S conversion conversion calculated calculated from from gas- analysis of S phase liquid T, content, GHSV, WHSV, products, products, HC Catalyst C. wt. % O.sub.2/S h.sup.1 h.sup.1 Time, h %* %** conversion, % CuZnAl (1) 400 0.042 300 2800 6 4 0 20 1.6 CuZnAl (1) 410 0.042 400 3400 6 4 0 23 2.5 CuZnAl (1) 470 0.042 500 4000 6 4 0 21 3.9 *Sulfur-containing products (which can be H2S and SO2) were not observed in gas-phase by GC analysis; **Sulfur conversion in liquid products was calculated from sulfur content measured by a Sulfur Analyzer Horiba SLFA-20 (accuracy 15 ppmw) and by ASE-2 X-ray Fluorescence Energy Dispersive (FED) Sulfur Analyzer.

(58) Gaseous sulfur containing compounds (i.e., SO.sub.2 and H.sub.2S) were not found, which indicates the sulfur compounds must have been adsorbed. Indeed, analysis of liquid products showed DBT, 4-MDBT, and 4,6-DMDBT. Table 11, which follows, summarizes the data on these compounds. No oxygenated products were found.

(59) It should be noted that the reduction of content of individual sulfur compounds, was confirmed via independent, GC-AED analysis.

(60) TABLE-US-00011 TABLE 11 The content of DBT, 4-MDBT and 4,6-DMBT in the diesel fuel for off-road application before and after the adsorptive/oxidative desulfurization test Content in the Content in the diesel Conversion of initial diesel fuel after the sulfur Compound fuel, ppm desulfurization test, ppm compound, % DBT 25 17 32 4-DMBT 22 17 23 4,6-DMDBT 41 26 37 *Sulfur conversion in liquid product was calculated from sulfur content measured by GC-AED analysis.

Example 17

(61) In a further set of experiments, a straight run diesel fuel was used, which contained 1.92 wt. % sulfur. Analysis of the fuel sample showed that it contained more light weight sulfur compounds (defined as having retention time less than 67, which is the retention time of DBT), and which are probably derivatives of benzothiophene. Other sulfur containing compounds in the fuel oil are: dibenzothiophene, 4-methyldibenzothiophene, 4,6-dimethyldibenzothiophene, as well as minor amounts of other alkyl substituted dibenzothiophenes.

(62) The sample was treated, in the same way all other samples were treated. The results are presented in Table 12.

(63) TABLE-US-00012 TABLE 12 Adsorptive/oxidative desulfurization of straight-run diesel fraction 180-360 C. S S conversion S conversion T content GHSV WHSV in gas-phase in liquid HC Catalyst C. wt. % O.sub.2/S h.sup.1 h.sup.1 Time h product % product* % Conversion % CuZnAl (1) 470 1.92 25 7900 6 6 17 17 7.3 CuZnAl (1) 600 1.92 30 10000 6 6 16 40 10.0 CuZnAl (1) 580 1.92 30 20000 6 6 40 41 8.0 (with N.sub.2) *Sulfur conversion in liquid product was calculated from sulfur content measured by ASE-2 X-ray Fluorescence Energy Dispersive (FED) Sulfur Analyzer.

(64) About 0.065 vol. % of SO.sub.2, and 6 vol. % of CO.sub.2 were monitored, at the outset of the reactor. When sulfur content in the liquid products was calculated, they were higher than those calculated when analyzing gas phase products. This is believed to be due to partial adsorption of sulfite and sulfate species on the surfaces of the catalysts, and also the presence of Cu.sub.2S (XRD data showed Cu.sub.1.96S, and Cu.sub.7S.sub.4). Total sulfur content on spent catalysts, according to CHNS analysis, was 6-10 wt. %. The adsorbed compounds could be removed by increasing GHSW, via adding inert gas to the flow whereby H.sub.2S and CO.sub.2 were produced. Concentrations reached 0.16 and 0.118 vol. %, respectively.

(65) The samples of this example and Example 15 were compared via GC-AED analysis. It found that the straight run diesel fuel of the example contained anywhere from 20-40% less sulfur compounds than the initial fuel sample. Sulfur conversion data bear this out.

(66) Results of the comparison are summarized in Table 13.

(67) TABLE-US-00013 TABLE 13 The content of DBT, 4-MDBT and 4,6-DMBT in the straight-run diesel fuel before and after the adsorptive/oxidative desulfurization test Content in the Content in the Conversion of initial diesel diesel fuel sulfur Compound fuel, ppm after the test, ppm compound, % DBT 183 121 34 4-DMBT 206 142 31 4,6-DMDBT 516 363 30 *Sulfur conversion in liquid product was calculated from sulfur content measured by GC-AED analysis.

Example 18

(68) The preceding examples demonstrated that the catalysts of the invention can be used in both oxidative and adsorptive removal of sulfur from feedstreams, such as hydrocarbon fuels. Experiments were carried out to determine if one or more factors were important in determining which mechanism predominated in these systems.

(69) Three tables follow, which summarize these results. In Table 14, a feedstock of dibenzothiophene in toluene was used, at various parameters. The results indicated that, when the other conditions are the same or similar, low GHSV favors adsorption as does a high O.sub.2/S ratio. Low GHSV as used herein refers to a GHSV less than 3000 h.sup.1, and high O.sub.2/ratio means more than 30.

(70) In addition to the data presented in Table 14, a sample of diesel fuel with a sulfur content of 1.93 wt. % was tested, where the only variable was GHSV. These data are presented in Table 15.

(71) The sulfur type also played an important role in adsorption. Table 15 summarizes the results from 4,6-DMDBT (line #2) and DBT (line #1) desulfurization. As seen, 4,6-DMDBT has a higher tendency to be adsorbed than DBT for the same operating conditions. This is a result of higher ability of 4,6-DMDBT to be oxidized into sulfates and sulfites as compared to DBT, due to the higher electron density of 4,6-DMDBT.

(72) The adsorption route involves the formation of sulfates and sulfites that need the addition of more oxygen as compared to the reaction route leading to SOx. This can be done by either reducing the contact time of oxygen or by increasing the oxygen concentration.

(73) TABLE-US-00014 TABLE 14 S removal, S removal, W % S GHSV WHSV W % Liquid Catalyst T C. (wt %) O.sub.2/S (h.sup.1) (h.sup.1) Gas Analysis Analysis CuZnAl 280 0.15 38 27430 28 52 39 (1) CuZnAl 300 0.16 50 2100 6 13 80 (1) CuZnAl 300 0.43 30 2700 6 13 60 (1) CuZnAl 326 0.46 30 4160 6 55 60 (1) CuZnAl 300 0.43 50 3800 6 20 77 (1)

(74) TABLE-US-00015 TABLE 15 S removal, W % S removal, W % Catalyst T C. S, W % O2/S GHSV, h.sup.1 WHSV, h.sup.1 Gas Analysis Liquid Analysis CuZnAl (1) 370 0.09 138 3000 6 39 36 CuZnAl (1) 370 0.09 138 3000 6 28 70

(75) The same trend was observed when a diesel fraction containing 1.93 W % sulfur was desulfurized. The results are shown in Table 16. As seen, a lower GHSV leads to more adsorption than reaction into SOx.

(76) TABLE-US-00016 TABLE 16 S removal, W % S removal, W % Catalyst T C. O.sub.2/S GHSV, h.sup.1 WHSV, h.sup.1 Gas Analysis Liquid Analysis CuZnAl (1) 600 30 15600 6 16 40 CuZnAl (1) 580 30 19900 6 44 41

Example 19

(77) This, and the examples which follow, deal with the regeneration of spent catalysts after adsorptive removal of sulfur was carried out.

(78) After the experiments described in Example 17, supra, were carried out, the catalyst was examined and FTIR data showed that it contained 6.5 wt. % sulfur in the form of sulfates and sulfites, as well as bulk copper sulfide (Cu.sub.1.96S and Cu.sub.7S.sub.4), as determined by XRD data. The spent catalyst also contained 11.5 wt. % carbon.

(79) The catalyst was regenerated by treatment at 350 C. for 4 hours with oxygen-containing gas with the oxygen content being increased gradually from 1 vol. % to 20 vol. %. Finally, the sample was calcined at 800 C. under air, for 4 hours.

(80) The regenerated catalyst had the following chemical composition in wt. %: Cu36.0; Zn12.1; Al14.2; Na0.02. The sulfur and carbon content in the catalyst were less than 0.3 and 0.1 wt. %, respectively. The catalyst had specific surface area 75 m.sup.2/g, pore volume 0.30 cm.sup.3/g and prevailing pore diameter equal to 12 nm. The catalyst phase composition exhibited a highly dispersed, spinel phase with lattice parameter a=8.02-8.1 and a crystal phase of CuO. The spinel phase exhibited particles with a size distribution of 2-10 nm (HRTEM data), and had a chemical composition Cu.sub.0.3Zn.sub.0.7Al.sub.2O.sub.4 as determined by EDX analysis.

Example 20

(81) Another sample of the spent catalyst of Example 17 was regenerated in an alternative method. Specifically, the sample was regenerated by treatment at 400 C. with a steam-nitrogen-oxygen mixture for 4 hours. The steam content of the mixture was 10 vol. % and the oxygen content was in the range 1-5 vol. %.

(82) The regenerated catalyst was identical in composition to that of Example 19.

Example 21

(83) Example 14, supra, describes using different catalysts to desulfurize different materials. In this example, the spent catalyst represented by CuZnAl(2), as used to remove sulfur from DBT in toluene was regenerated. Prior to regeneration, the spent catalyst was determined to contain 2.3 wt. % sulfur, and 7.3 wt. % carbon.

(84) The sample was regenerated by treatment under a hydrogen-containing gas mixture (5 vol. % H.sub.2 in nitrogen), with the temperature being increased from 120 C. to 530 C. at a rate 60-120 C./hr. Finally the sample was hydrotreated at 530 C. for 2 hours.

(85) The regenerated catalyst had the following composition in wt. %:Cu26.3; Zn15.8; Al22.3. The sulfur and carbon contents were less than 0.5 and 2.0 wt. %, respectively. The catalyst had a specific surface area 70 m.sup.2/g, pore volume 0.27 cm.sup.3/g and prevailing pore diameter equal to 11 nm. The catalyst phase composition exhibited a highly dispersed spinel phase with a lattice parameter a=8.02-8.2 and a crystal phase of Cu.sup.0 and Cu.sub.2O.

Example 22

(86) A second sample of the spent catalyst discussed in Example 21 was regenerated, by treatment at 360 C. for 2 hours under a hydrogen-containing gas mixture (5 vol. % H.sub.2 in nitrogen), with the temperature increased from 120 C. to 360 C. at a rate 60-90 C./hrs. Then, the sample was kept at 350 C. under an inert gas for 1 hour and under air flow for 2 hours.

(87) The regenerated catalyst had the same composition as that of Example 21, and sulfur and carbon content less than 0.5 and 0.4 wt. %. The catalyst had a specific surface area of 75 m.sup.2/g, a pore volume of 0.33 cm.sup.3/g and a prevailing pore diameter of 12 nm. The catalyst phase composition exhibited by a highly dispersed spinel phase with a lattice parameter a=8.02-8.2 and a crystal phases of CuO.

Example 23

(88) The catalyst represented by CuZnAl(3) and used the same way CuZnAl(2) was used, as discussed in Examples 21 and 22, was regenerated via high temperature pyrolysis. Prior to the treatment, the spent catalyst contained 2.2 wt. % surface SO.sub.4.sup.2+SO.sub.3.sup.2, and 8.3 wt. % carbon.

(89) This sample was regenerated by high temperature pyrolysis at 760 C. under an inert atmosphere, for 4 hours, resulting in calcination.

(90) The calcined catalyst had the following composition in wt. %: Cu20.9; Zn17.1; Al23.9; Ce0.5. The sulfur and carbon contents were less than 0.3 and 2.5 wt. % (the carbon was in the form of carbonates), respectively. The catalyst had a specific surface area 70 m.sup.2/g, pore volume 0.17 cm.sup.3/g and prevailing pore diameter equal to 8.5 nm. The catalyst phase composition exhibited by a highly dispersed spinel phase with a lattice parameter a=8.02-8.2 , an chemical composition Cu.sub.0.5Zn.sub.0.5Al.sub.2O.sub.4, and a crystal phase of CuO.

(91) The foregoing examples describe features of the invention which include a catalytic composition useful, e.g., in oxidative and/or adsorptive removal of sulfur from gaseous, sulfur containing hydrocarbons, as well as processes for making the compositions, and their use.

(92) The catalytic compositions comprise oxides of copper, zinc, and aluminum in defined weight percent ranges, and may also contain cerium oxide. The compositions exhibit an X-ray amorphous oxides phase with highly dispersed oxides of Zn, Cu, and optionally Ce.

(93) As noted, supra, the compositions contain defined amounts of the metallic oxides. The weight percentages permitted by the invention are 5 to less than 20 weight percent zinc oxide, from 10 to 50 weight percent copper oxide, and from 20 to 70 weight percent of aluminum oxide. When cerium oxide is present, its amount can range from 0.1 to 10 wt percent of the composition.

(94) The aforementioned structure has a lattice parameter corresponding to spinel, according to HRTEM data and the chemical formula Cu.sub.xZn.sub.1-xAl.sub.2O.sub.4, found from EDX analysis which is in accordance with the standard formula for spinels, i.e., MAl.sub.2O.sub.4, where M signifies a metal or combination of metals. Within the spinel, the ZnO and CuO are present as highly dispersed crystals. If cerium oxide is present, it is in particle form, with particles ranging in diameter from 5 nm to 10 nm. Preferably, X ranges from 0.1 to 0.6, more preferably, from 0.2 to 0.5.

(95) The composition of the invention preferably are granular in nature, and may be formed into various embodiments such as a cylinder, a sphere, a trilobe, or a quatrolobe, preferably via processes discussed infra. The granules of the compositions preferably have diameters ranging from 1 mm to 4 mm.

(96) The compositions preferably have specific surface areas ranging from 10 m.sup.2/g to 100 m.sup.2/g, more preferably 50 m.sup.2/g to 100 m.sup.2/g, with pores ranging from 8 nm to 12 nm, more preferably, 8 nm to 10 nm. In preferred embodiments, the weight percentages are: 20-45CuO, 10.fwdarw.20ZnO, and 20-70Al.sub.2O.sub.3, and most preferably 30-45 CuO, 12.fwdarw.20ZnO, and 20-40Al.sub.2O.sub.3.

(97) The catalytic compositions of the invention are made by preparing an aqueous solution of the nitrates of Cu, Zn, and Al, and optionally Ce, and then combining this solution with an aqueous alkaline solution which contains NaOH, and/or one or more of (NH.sub.4).sub.2CO.sub.3, Na.sub.2CO.sub.3 and NH.sub.4HCO.sub.3.

(98) These solutions are combined at a temperature which may range from about 50 C. to about 65 C., and at a pH of from about 6.5 to about 14. The resulting hydroxides, carbonates, and/or hydroxycarbonates precipitate and are then filtered, washed, and dried, for at least ten hours, at a temperature of at least 100 C. After this, the resulting dried material is calcined, for about 2-4 hours, at a temperature of at least 450 C., to form the composition described herein.

(99) The precipitate may be aged prior to the filtering and washing, as elaborated in the examples.

(100) It is frequently desirable to form composites of the catalytic composition, and this is preferably done by adding a binder to the compositions prior to calcination. The binder may be, e.g., polyethylene oxide, polyvinyl alcohol, aluminum pseudoboehmite, silica gel, or mixtures thereof. The binder may be added in amounts ranging from about 1 wt % to about 20 wt % of the precipitate, preferably from 1-10 wt. % or in the case of hydroxides 3-20 wt. %. The resulting mixture may be extruded through, e.g., a forming die, and then dried, preferably at room temperature, for 24 hours, followed by drying at about 100 C. for 2-4 hours. The extrusion product is then heated slowly, e.g., by increasing temperatures by 2-5 C. every minute until a temperature of 500 C. is reached, followed by calcination at 500 C. for 2-4 hours.

(101) In practice, the compositions are used by combining them with a sulfur containing hydrocarbon, in gaseous form, together with an oxygen source, for a time sufficient for at least a portion of the sulfur to be oxidized to, e.g., SO.sub.2. The oxygen source is preferably pure oxygen, but may be air, or any other oxygen source. Preferably, the materials recited supra are combined at conditions which include pressure of from 1-bars, temperature of from 200 C. to 600 C., with a weight hourly space velocity of from 1-20 h.sup.1, gas hourly space velocity of from 1,000-20,000 h.sup.1, with an oxygen carbon molar ratio of from 0.01 to 0.1, and a molar ratio of oxygen and sulfur of from 1 to 150. Preferably, the pressure ranges from 1-10 bars, most preferably 1-5 bars, the temperature is preferably from 250-500 C., and is most preferably 300-500 C. The gas hourly space velocity is preferably 5,000-15,000 h.sup.1, most preferably 5,000 to 10,000 h.sup.1, while the preferred molar ration of O.sub.2/C ranges from 0.02-0.1, and most preferably from 0.05-0.1, while that of O.sub.2/S is from 10-100, and most preferably, from 20-50.

(102) The feedstock, i.e., the sulfur containing hydrocarbon, will vary, but preferably is one with a boiling point above 36 C., and even more preferably, above 565 C.

(103) In practice, the catalytic compositions are used in the form of, e.g., fixed beds, ebullated beds, moving beds, or fluidized beds.

(104) Other features of the invention will be clear to the skilled artisan and need not be reiterated here.

(105) The terms and expression which have been employed are used as terms of description and not of limitation, and there is no intention in the use of such terms and expression of excluding any equivalents of the features shown and described or portions thereof, it being recognized that various modifications are possible within the scope of the invention.