CATALYSTS, PROCESS FOR OBTAINING AND STEAM PRE-REFORMING PROCESS OF HYDROCARBONS

Abstract

The present invention refers to a pre-reforming catalyst comprised of nickel oxide and having platinum content between 0.01 to 0.5%, characterized in that the catalyst is resistant to deactivation by passage of steam in the absence of a reducing agent and to a process for producing hydrogen or hydrogen-rich gases.

Claims

1.-16. (canceled).

17. A steam pre-reforming catalyst, comprising: a) an inorganic oxide support selected from alumina, magnesium aluminate, or mixture thereof; b) a mixture of nickel, lanthanum and cerium oxides, with the total content of nickel expressed as nickel oxide (NiO), from 6 to 15:1 (w/w) between NiO and La.sub.2O.sub.3, and 2 to 4:1 (w/w) between Ce.sub.2O.sub.3 and La.sub.2O.sub.3, and a total NiO content between 5 to 50% w/w; and c) platinum in a concentration in the range of 0.05 to 0.5% w/w, calculated as a metallic element in a final catalyst.

18. The steam pre-reforming catalyst of claim 17, characterized in that the mixture of nickel, lanthanum and cerium oxides has a total content of NiO between 7 and 30% w/w.

19. The steam pre-reforming catalyst of claim 17, characterized in that the platinum has a concentration in the range of 0.05 to 0.2% by weight, calculated as the metallic element in the final catalyst.

20. A process for obtaining the steam pre-reforming catalyst of claim 17, characterized by comprising the following steps: a) preparing a solution of an inorganic salt of nickel, in the form of nitrate, acetate, or nickel carbon containing inorganic salts of lanthanum and cerium; b) impregnating the support of inorganic oxide by a pore volume (wet spot) technique or by a method of excess solution; c) drying the inorganic oxide material impregnated with solution containing nickel in air, at temperatures from 50 to 140° C. for 1 to 24 hours; d) calcinating the impregnated inorganic oxide material in static air or air flow between 300 to 600° C., for 1 to 4 hours; e) preparing a solution of an inorganic salt of platinum; f) impregnating the inorganic oxide material containing nickel, lanthanum and cerium by the pore volume technique (wet spot) or by the excess solution technique; and g) calcinating the impregnated inorganic oxide material in static air or air flow between 350 to 650° C., for 1 to 4 hours, to obtain the pre-reforming catalyst.

21. The process of obtaining the steam pre-forming catalyst of claim 20, characterized in that the solution prepared is aqueous.

22. The process of obtaining the steam pre-forming catalyst of claim 20, characterized in that the lanthanum and cerium salts are nitrates.

23. The process of obtaining the steam pre-forming catalyst of claim 20, characterized in that the calcination step d) can be replaced with a direct reduction step in flow with reducing agent under temperature conditions between 300 to 800° C., for 1 to 5 h, and then cooled and submitted to an air flow at temperatures between 20 to 60° C., for 1 to 5 h.

24. The process of obtaining the steam pre-forming catalyst of claim 23, characterized in that the reducing agent is selected from hydrogen, formaldehyde, or methanol.

25. A steam pre-reforming catalyst, comprising: a) nickel as active phase; and b) platinum in a concentration in the range of 0.05 to 0.5% w/w, calculated as a metallic element in the final catalyst.

26. The steam pre-reforming catalyst of claim 25, characterized in that the platinum has a concentration in the range from 0.05 to 0.2% w/w, calculated as the metallic element in the final catalyst.

27. A process for obtaining the steam pre-reforming catalyst of claim 25, characterized by comprising the following steps: a) preparing a solution of an inorganic salt of platinum; b) impregnating a commercial catalyst containing nickel in contents greater than 30% w/w, by a pore volume technique (wet spot) or by an excess solution technique, followed by drying the material thus prepared at temperatures between 60 and 120° C. for 1 to 10 h; and c) calcinating the material in static air or in air flow between 300° C. to 500° C., for 1 to 2 hours, to obtain the pre-reforming catalyst.

28. The process of obtaining the steam pre-forming catalyst of claim 27, characterized in that the prepared solution is aqueous.

29. The process of obtaining the steam pre-forming catalyst of claim 27, characterized in that the calcination step c) is omitted through the use of salts that do not contain the chloride element.

30. A process for pre-reforming of hydrocarbons, characterized by being carried out with the catalyst of claim 17 in a fixed bed, carried out in the presence of steam with a steam/carbon ratio between 0.8 to 3.0 mol/mol, at a H.sub.2/load ratio between 0.1 to 0.3 Nm.sup.3/g, at a temperature between 300° C. to 550° C., at a pressure between 2 to 40 kgf/cm.sup.2, and at a spatial velocity between 1,200 to 2,000 h.sup.−1, based on the hydrocarbon flow.

31. The process for pre-reforming of hydrocarbons of claim 30, characterized by being carried out in the presence of steam with a steam/carbon ratio between 1 and 2 mol/mol and hydrogen in a H.sub.2/load ratio between 0.1 to 0.2 Nm.sup.3/g, at a temperature between 330° C. to 500° C., and at a pressures between 20 to 30 kgf/cm.sup.2.

32. The process for pre-reforming of hydrocarbons of claim 30, characterized in that the hydrocarbon comprises natural gas, or petroleum liquefied gas or naphtha.

33. A process for pre-reforming of hydrocarbons, characterized by being carried out with the catalyst of claim 25 in a fixed bed, carried out in the presence of steam with a steam/carbon ratio between 0.8 to 3.0 mol/mol, at a H.sub.2/load ratio between 0.1 to 0.3 Nm.sup.3/g, at a temperature between 300° C. to 550° C., at a pressure between 2 to 40 kgf/cm.sup.2, and at a spatial velocity between 1,200 to 2,000 h.sup.−1, based on the hydrocarbon flow.

34. The process for pre-reforming of hydrocarbons of claim 33, characterized by being carried out in the presence of steam with a steam/carbon ratio between 1 and 2 mol/mol and hydrogen in an H.sub.2/load ratio between 0.1 to 0.2 Nm.sup.3/g, at a temperature between 330° C. to 500° C., and at a pressures between 20 to 30 kgf/cm.sup.2.

35. The process for pre-reforming of hydrocarbons of claim 33, characterized in that the hydrocarbon comprises natural gas, or petroleum liquefied gas or naphtha.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0020] Preliminarily, it is emphasized that the following description is taken from preferred embodiments of the invention. As will be evident to any person that is skilled in the art, however, the invention is not limited to these embodiments, but only to the scope of the protection defined in the claims.

[0021] The present invention can be applied to commercial catalysts based on nickel as active phase, by means of promoting the catalysts with a Pt content at a concentration in the range of 0.05 to 0.5%, preferably between 0.05 to 0.2% by weight, calculated as the metallic element in the final catalyst, being produced by the preparation process characterized by presenting the following steps:

[0022] 1. Preparation of a solution, preferably aqueous, of an inorganic Pt salt;

[0023] 2. Impregnation of the commercial catalyst containing nickel, by the technique known as pore volume (wet) or by the excess solution technique, followed by drying the material thus prepared at temperatures between 60 to 120° C. for 1 to 10 h;

[0024] 3. Calcination of the static air material or in air flow between 300° C. to 500° C., for 1 to 2 hours, to obtain the pre-reforming catalyst that is resistant to deactivation by the passage of steam in the absence of hydrocarbons or a reducing agent, such as H.sub.2 or methanol.

Optionally, the calcination step can be omitted, using in this case, preferably, salts which do not contain elements such as chloride, such as the H.sub.2PtCl.sub.6, which once released “insitu”, can lead to deactivation problems of the catalysts used in the process for producing H.sub.2 and/or corrosion problems in lines or equipment. The commercial pre-reforming catalysts based on nickel promoted with low Pt contents, in accordance with the present invention, do not deactivate by the passage of steam in typical conditions, bringing advantages in starting the H.sub.2 production unit or avoiding emergency procedure occurrences or even the occurrence of unscheduled stops when a fault can occur in the hydrocarbon or H.sub.2 recycle flow.

[0025] It can further be advantageous, to include the Pt in a pre-reforming catalyst formulation based on nickel containing Pt at a concentration in the range of 0.05 to 0.5%, preferably between 0.05 to 0.2% by weight, calculated as metallic element in the final catalyst and constituted by an inorganic oxide support, selected preferably from alumina, magnesium aluminate, calcium aluminate or mixture thereof. The nickel-based catalyst can further have lanthanum and cerium, with proportions between these elements from 6 to 15:1 (by weight) between NiO and La.sub.2O.sub.3 and 2 to 4:1 (by weight) between Ce.sub.2O.sub.3 and La.sub.2O.sub.3 and a total content of NiO between 5 and 50% by weight, preferably between 7 and 30% by weight, being produced by the preparation process containing the following steps:

[0026] 1) Preparation of a solution, preferably aqueous, of an inorganic nickel salt, preferably nitrate, acetate, or carbonate, containing lanthanum and cerium, preferably in the form of nitrates;

[0027] 2) Impregnation of the inorganic oxide support by the techniques known of pore volume (wet) or by the excess solution method;

[0028] 3) Drying of the inorganic oxide material impregnated with solution containing nickel by air, at temperatures from 50 to 140° C. for 1 to 24 hours;

[0029] 4) Calcination of the inorganic oxide material impregnated with static air or air flow between 300 to 600° C., for 1 to 4 hours. Alternatively, the steps (2-4) can be repeated more than once until the desired NiO content is reached in the support;

[0030] 5) Preparation of a solution, preferably aqueous, of an inorganic Pt salt;

[0031] 6) Impregnation of the inorganic oxide material containing nickel by the known technique of pore volume (wet) or by the excess solution technique;

[0032] 7) Calcination of the inorganic oxide material impregnated with static air or air flow between 350 to 650° C., for 1 to 4 hours.

[0033] The step 4 of calcination can be replaced with the direct flow reduction of a reducing agent, selected from hydrogen, formaldehyde, or methanol at temperature conditions between 300 to 800° C., for 1 to 5 h, and then cooled and submitted to an air flow at temperatures between 20 to 60° C., for 1 to 5 h, to avoid the material having a pyrophoric character when handled.

[0034] Optionally, the solution prepared in item 1 can contain Pt salt, thus it will not be necessary to carry out steps 5, 6 and 7.

[0035] The catalyst of the present invention is prepared from an inorganic oxide support having low surface acidity, preferably selected from the group consisting of alumina, calcium alum inate, magnesium alum inate or a combination of these materials. The support particles can be in several forms suitable to industrial use in the steam pre-reforming process, such as spheres, cylinders or cylinders having a central orifice (Rashing rings).

[0036] A second purpose of the present invention is to provide the use of a pre-reform ing catalyst that is resistant to deactivation by the passage of steam in the pre-reform ing step for producing hydrogen or hydrogen rich gases, such as synthesis gas or natural synthetic gas. The step can be carried out using a fixed-bed catalyst with hydrocarbon feed, selected from natural gas, liquefied petroleum gas or naphtha with boiling point of up to 250° C., in the presence of steam and H.sup.2. The steam/carbon ratio is selected between 0.8 to 3.0 mol/mol, preferably between 1 to 2 mol/mol, the H.sub.2/load ratio is selected between 0.1 to 0.3 Nm.sup.3/kg of load, preferably between 0.15 to 0.25 Nm.sup.3H.sub.2/ kg of load, temperatures along the reactor between 300° C. to 550° C., preferably between 330° C. to 500° C., pressures between 2 to 40 kgf/cm.sup.2, preferably between 20 to 30 kgf/cm.sup.2 and spatial speeds between 1.200 to 2.000 h.sup.-1 (based on the hydrocarbon blow and for a typical campaign time of 2 years, preferably 3 years).

EXAMPLES

[0037] Next, so that the invention can be better understood, there are presented trials which illustrate the invention without, however, being considered as limitative.

Example 1

[0038] This example illustrates the preparation of a pre-reforming catalyst based on nickel, lanthanum, and cerium over an alumina type support. One hundred (100) grams of theta-alumina (SPH 508F by Axens, with pore volume of 0.7 cm.sup.3/g in the shape of spheres of 3 to 4 mm diameter) was impregnated with 70 ml of aqueous solution containing 2.95 grams of La(NO.sub.3).sub.3.6H.sub.2O, 8.82 grams of Ce(NO.sub.3).sub.3.6H.sub.2O and 33.03 grams of Ni(NO.sub.3).sub.2.6H.sub.2O. The material was dried at 60° C. for 2 hours; heated in static air from 60° C. to 120° C. at the rate of 1° C./min and then to 250° C. at the rate of 1.4° C./min. The catalyst was then calcined at 450° C. for 4.5 hours, having been obtained a Ni—Ce—La/theta-alumina catalyst containing 7.6% (p/p) of NiO, 1.0% (p/p) of La.sub.2O.sub.3 and 3.0% p/p of Ce.sub.2O.sub.3%.

Example 2

[0039] This example illustrates the use of a pre-reforming commercial catalyst having nickel contents between 40 and 60% (by weight) provided in the pre-calcined state. The commercial pre-reforming catalyst does not have platinum thus, this catalyst will be compared with the other catalysts prepared in this invention. The results are shown in Table 1.

Example 3

[0040] This example illustrates the preparation of a pre-reforming catalyst according to the present invention. Thirty grams of the catalyst of EXAMPLE 1, previously ground in the granulometric range of 100 to 150 mesh, were impregnated by the pore volume technique with an aqueous solution containing 0.08 g of H.sub.2PtCl.sub.6H.sub.2O. The material was dried at a temperature from 90 to 120° C. for 12 h and then, was air calcinated at a temperature of 450° C. for 4 h, having been obtained a pre-reforming catalyst of the Pt—Ni—Ce—La/theta-alumina type containing 0.1% (by weight) of Pt, 7.6% (by weight) of NiO, 1.0% (by weight) of La.sub.2O.sub.3 and 3.0% by weight of Ce.sub.2O.sub.3%.

Example 4

[0041] This example illustrates the preparation of a pre-reforming catalyst according to the present invention. Thirty grams of the commercial catalyst of the pre-reformer of EXAMPLE 2, previously ground at the granulometric range from 100 to 150 mesh, were impregnated by the pore volume technique with an aqueous solution containing 0.08 g of H.sub.2PtCl.sub.6H.sub.2O. The material was dried at a temperature from 90 to 120° C. for 12 h and then, air calcined at a temperature of 450° C. for 4 h, having been obtained a pre-reforming catalyst based on Ni and containing 0.1% (by weight) of Pt.

Example 5

[0042] This example illustrates the accelerated deactivation method to which the pre-reforming catalysts used according to examples 1 to 4 were submitted by means of the passage of steam (steaming) in the absence of hydrocarbon or a reducing agent. Two grams of the materials described in examples 1 to 4 were carried to a steel reactor at a catalyst test unit. The catalyst was heated at a flow of 600 ml/min of H.sub.2 and at a rate of 10° C./min at room temperature at 450° C., which was maintained for 2 h for reduction (activation) of the species of nickel oxide to metallic nickel. Then, the H.sub.2 was replaced with N.sub.2 and the unit was purged for 1 h, when it was fed with water steam. This condition of passage of water steam at 450° C. was maintained for time periods between 2 to 40 h at a pressure of 20 atm.

Example 6

[0043] This example illustrates the excellent resistance to deactivation by the passage of steam in the absence of a reducing agent, of the catalysts prepared according to the present invention. The initial reaction activity of the steam reforming was determined by a commercial AutoChem II (Micromeritcs) equipment. The tests were carried out using 500 mg of catalyst ground at a range from 100 to 150 mesh. The trials were carried out at atmospheric pressure and at temperature of 450° C., 500° C. and 550° C. by the passage of 50 ml of a current containing 50% v/v of methane, 5% of H.sub.2 and 45% of argonium saturated with water steam at 90° C. The effluent gases of the reactor were analyzed by gas chromatography and the activity measured by the methane conversion degree.

[0044] Table 1 shows results of the catalytic activity, expressed as methane conversion, of the materials described in the examples 1 to 4, before and after being submitted to the accelerated deactivation process by the passage of steam in the absence of hydrocarbons or a reducing agent, as described in example 5. The results show that it is possible to obtain a high resistance to deactivation by the passage of steam in the absence of reducing agents for the catalysts prepared in accordance with the present invention. Additionally, comparing examples 3 and 4, we can observe that the low content of Pt added to the nickel commercial catalyst caused a significant increase of activity, which can be explained by the mechanism of favoring a higher reduction of species of nickel oxide.

TABLE-US-00001 TABLE 1 results of the methane conversion activity in pre-reforming conditions over catalysts submitted to deactivation procedure by passage of steam in the absence of hydrocarbons or reducing gases. Duration of Methane conversion at Catalyst deactivation (h).sup.(1) 500° C. (% v/v) Ni/Ce/La/theta-alumina 0 31.0 (example 1) 24 22.5 48 0 Ni/commercial-support 0 17.5 (example 2) 24 0 48 0 Pt/Ni/Ce/La/theta- 0 32.0 alumina (example 3) 24 23.0 48 20.0 Pt/Ni/commercial 0 33.4 support (example 4) 24 30.0 48 17.2 Note: .sup.(1)as per information given in example 5.

[0045] Therefore, the nickel catalysts with low platinum content prepared according to examples 1 to 4 present for the steam pre-reforming of hydrocarbons high resistance to deactivation by the passage of steam in the absence of hydrocarbons or of a reducing agent, such as hydrogen or methanol, constituted by nickel oxide and platinum, in contents between 0.05 to 0.5% m/m, preferably between 0.05 a 0.2% m/m, based on the final catalyst.