US3506417A - Hydrocarbon reforming - Google Patents

Description

United States Patent Office 3,506,417 Patented Apr. 14, 1970 3,506,417 HYDROCARBON REFORMING Harold J. Hepp and E. 0. Box, Jr., Bartlesville, kla., as-

signors to Phillips Petroleum Company, a corporation of Delaware N0 Drawing. Filed May 13, 1966, Ser. No. 549,799 Int. Cl. Cg 11/02, 11/04 US. Cl. 48197 4 Claims ABSTRACT OF THE DISCLOSURE This invention relates to the production of methanecontaining gases fungible with natural gas from nonmethane containing feedstocks. In accordance with one aspect, this invention relates to the conversion of hydrocarbons containing from 2 to 15 carbon atoms per molecule to a gaseous product rich in methane by contacting in the presence of steam with a nickel or ruthenium catalyst. In accordance with another aspect, this invention relates to the conversion of light hydrocarbons such as propane to a gaseous product rich in methane, fungible with natural gas, with an alkalized nickel or platinium group metal catalyst in the presence of steam.

Utility companies which distribute gas for household or other use have an increasingly acute need for an economical means of supplying gas during peak-load periods, During cold weather, for example, demand may be double or triple the volume used on a mild day. In many instances, this peak-load demand is met by adding propane-air mixtures to the gas. Because the quantity of propane-air that can be blended is limited, there is a need for an economic process that can be used to supply peakload demand.

Accordingly, the present invention relates to an improved process for the production of methane-containing gases fungible with natural gas from hydrocarbon feedstocks.

An object of this invention is to provide a new and improved catalyst for the conversion of a hydrocarbon to methane-rich gas.

Another object of this invention is to provide a new and improved catalyst having increased catalyst life, useful for the steam reforming of hydrocarbons to produce methane-rich gaseous product.

Other aspects, objects, as well as the several advantages of the invention will be apparent to one skilled in the art from a study of this disclosure and the appended claims.

According to the invention, a process is provided for the production of methane-containing gases fungible with natural gas from non-methane feedstocks which comprises contacting said feedstock and steam at a temperature below about 1000 F. with an alkali metal or alkaline earth metal promoted catalyst selected from (a) nickel and silica-containing supports, and (b) supported platinum group metals.

The non-methane feedstocks processable to methanerich product according to the invention comprises hydrocarbons having from 2 to about 15 carbon atoms per molecule. Such feedstocks preferably contain predominantly paraffinic hydrocarbon such as propane, butane, hexane, octane, decane, dodecane, pentadecane and the like. The hydrocarbon feedstock can contain minor amounts of unsaturated materials when desired. The higher molecular weight hydrocarbons in the feedstock will ordinarily have a maximum boiling point of about 500 F.

The reforming temperature employed does not exceed 1000 F., and preferably will be in the range 650 1000 F. The reaction pressure will ordinarily be suflicient to maintain liquid phase conditions, such as 100-500 p.s.i.g, The steam to hydrocarbon mol ratio is ordinarily at least 2.5 to 1, generally in the range 2.5-6 to 1. The total gaseous hourly space velocity (GHSV) ordinarily ranges from SOD-40,000 volumes of gas per volume of catalyst per hour, calculated at 32 F. and one atmosphere.

The nickel catalyst used in the process of our invention is preferably a nickel-kieselguhr catalyst containing from 5 to 90 weight percent nickel on a reduced basis and 0.5 to 10 weight percent alkali or alkaline earth metal. In this application, the values for weight percent are based on the total weight of the catalyst. Instead of kieselguhr, other natural or synthetic silica-containing material, such as silica, silica-alumina, silica-zirconia, the natural or synthetic crystalline aluminosilicates, and the like, can be used. The alkali metal or alkaline earth metal can be applied to the catalyst as the hydroxide, carbonate, or other soluble salt. Potassium carbonate is a presently preferred alkaline material.

The nickel catalyst of the invention exhibits a considerably longer catalyst life than is obtained with known nickel-alumina catalyst. The longer life is a result of the fact that silica-containing supports are considerably more stable in the presence of steam than alumina-containing supports. As a result of this higher steam stability, catalysts of the invention have a useful life 2 to 10 times longer than that of the alumina base catalyst.

The platinum group metals for use in this invention can be ruthenium, rhodium, osmium, iridium, platinum, palladium, or mixtures of such metals and/or their compounds can be used. Ruthenium is a presently preferred platinum group metal.

The platinum groupmetals can be incorporated into any of the known natural or synthetic refractory inorganic oxide materials known as supports such as alumina, silica, magnesia, zirconia, silica-alumina, the natural or crystalline aluminosilicates, and the like. The amount of platinum group metal present in the catalyst composition can vary from 0.01 to 20 weight percent, preferably in amounts less than about 10 percent by weight. The amount of alkali metal or alkaline earth metal present in the catalyst can range from 0.5 to 10 weight percent. The alkali metal or alkaline earth metal can be applied as hydroxide, carbonate, or other soluble salt. The term soluble is intended to include either aqueous or nonaqueous solvents, although water is presently preferred. Potassium carbonate is the presently preferred alkali or alkaline earth compound.

As is demonstrated by the specific working examples hereinbelow, steam reforming of hydrocarbons according to the invention results in a gaseous product fungible with natural gas, which product contains as much as 92 mol percent methane.

In actual operation, according to the invention, the steam reforming zone is charged with the catalyst, which includes an alkali or alkaline earth metal compound such as potassium carbonate, sodium carbonate, lithium carbonate, potassium bicarbonate, sodium bicarbonate, lithium bicarbonate, potassium acetate, barium acetate, magnesium nitrate, beryllium nitrate, strontium nitrate, strontium acetate, barium hydroxide, cesium bicarbonate, cesium hydroxide, rubidium carbonate, rubidium nitrate, calcium nitrate, calcium chromate, potassium dichromate, potassium hydroxide, sodium hydroxide, lithium hydroxide, and the like. Mixtures of the alkali metal and/or alkaline earth metal compounds can also be employed. It is to be understood that the term catalyst as employed herein is intended to include the contact mass as prepared and charged to the reaction zone, that is, for example, nickel or ruthenium, or the oxide or salt thereof, in combination with the alkali or alkaline earth metal compound and a support material, as well as any modifled physical or chemical form to which the contact mass can be converted prior to or during the course of the steam reforming process.

The catalyst can be prepared by any of the known procedures. Ordinarily, the support, in the form of discrete particles, is impregnated with a solution of the desired nickel or platinum group metal compound, followed by calcining, impregnation with a solution of an alkali or alkaline earth metal compound, followed by calcining. Reduction with hydrogen can be done at any time subsequent to addition of the metal, either prior to or during use.

EXAMPLE I A catalyst used to demonstrate the process of the invention was an alkali metal-promoted nickel kieselguhr in the form of /s-inch pellets. The nickel content was 72 weight percent (after reduction) and the potassium carbonate content was 1.6 weight percent (equivalent to 0.9 percent potassium). It was prepared by impregnating kieselguhr with an aqueous solution of a soluble nickel salt, calcining, impregnating with aqueous potassium carbonate, calcining, and reducing in hydrogen for about 7 hours at 650 F. and 1 hour at 840 F. Results obtained in reforming propane with steam were:

Run Number 1 Temperature, F. 840 Pressure, p.s.i.g 325 GHSV, total h 818 H O/C H ratio, mol 4.0 Efl'luent gas composition, mol percent (dry):

H 7.0 CH 77.1 C 03 CO 6 C3H3 I111 CO free basis, mol percent (dry):

H 8.3 CH 91.3 C0 0 4 Heating value, B.t.u. cu. ft.:

Dry, 60 F./30 Hg 952 Saturated, 60 F./30" Hg 935 Wobbe Number, W 1304 Weaver Flame Speed Factor, S 16.4

EXAMPLE II A catalyst used to further demonstrate the process of our invention was an alkali-promoted ruthenium-alumina in the form of As-inch pellets. The ruthenium content was 0.5 weight percent and the potassium carbonate content Was 1.6 Weight percent (equivalent to 0.9 percent potassium). It Was prepared by impregnating alumina with an aqueous solution of a soluble ruthenium salt, calcining, impregnating with an aqueous solution of potassium carbonate, calcining, and reducing in hydrogen for 1 hour at 800 F. Results obtained in reforming propane with steam are:

Run Number 2 3 4 Temperature, F 798 863 1, 020 Pressure, p.s.i.g 320 320 320 Space velocity, total, GHSV 3, 780 3, 070 3, 710 HzQ/CsHa ratio, mol 4. 0 2. 7 3. 7 Effluent gas composition, mol percent (dry):

H 8.6 6.4 23.3 74. 4 78. 3 58. 6 0. 6 0. 5 1. O 14. 7 14. 2 17. 1 1. 7 Nil Nil 10. 3 7. 5 28. 1 89. 0 91. Q 70. 7 C0 0. 7 0. 6 1. 2 Heating values, B.t.u./cu. It;

Dry, 60 F./30 Hg 940 959 813 Saturated, 60 F./30 Hg 923 942 792 Wobbe number, W 1, 290 1, 320 1, 250 Weaver flame speed, S 17. 0 16. 2 23. 9

Interchangeability or fungibility of other gases with natural gas is related to a number of factors, the major ones of which are (1) the tendency of the flame to flash back, (2) the tendency of the flame to lift off the burner, and (3) the tendency of the gas to burn incompletely. As a result of studies made by a number of workers, the following diagram has been developed by P. Delbourg (Compt. rend. congr. ind. gaz, 68th Congr., Paris, 1951, 744-96) for the limits of interchangeability of other gases with natural gas:

Weaver Flame Speed Factor S In this diagram the Wobbe Number is related to the calorific value of the gas (in B.t.u. per cubic foot) by the following equation:

W=calorific value/ (specific gravity) Calculation of the Weaver Flame Speed Factor S is described in J. Res. Natl. Bur. Stds., 46, 213-245 (1951).

It is apparent that the product of the process of our invention falls within the area of fungi-bility, and is thus a highly desirable material for use in meeting peak-load demand.

It is further apparent that the product of a run made according to the prior art falls outside the area of fungibility.

Reasonable variation and modification are possible within the scope of the foregoing disclosure and the appended claims to the invention, the essence of which is that there is provided process for the production of methane-containing gases fungible with natural gas from nonmethane feedstocks which comprises contacting such feedstocks at a temperature below 1000" F. with steam and an alkalized nickel or platinum group metal catalyst.

We claim:

1. A process for the production of methane-containing gases fungible with natural gas from propane feedstocks which comprises contacting a propane feedstock and steam wherein the steam to hydrocarbon mol ratio is 2.5:1 to 6:1 with a catalyst selected from the group consisting of (a) silica supported nickel promoted with 05-10 weight percent, based on the total catalyst, of a promoter selected from the group consisting of alkali metals and alkaline earth metals, and

(b) a supported platinum group metal promoted with 05-10 weight percent, based on the total catalyst, of a promoter selected from the group consisting of alkali metals and alkaline earth metals at an elevated temperature of 650-1000 F. and a pressure of 100 500 p.s.i.g. and a total GHSV of 50040000 to produce a reaction efiluent gas containing in excess of 70 mol percent methane.

2. A process according to claim 1 wherein the amount of nickel in (a) is from 5-90 weight percent on a reduced basis and the amount of platinum group metal in (b) is from 0.01 to 20 weight percent.

3. A process according to claim 1 wherein the catalyst is nickel-kieselg-uhr promoted with potassium.

4. A process according to claim 1 wherein the catalyst is ruthenium-alumina promoted with potassium.

References Cited UNITED STATES PATENTS Martin 252-472 X Michael et al 252472 X Rottig 252472 Nonnenmacher 48-212 McMahon.

Anderson et al. 48-213 XR Dowden et al.

Taylor et al. 48-197 X Dowden 23-212 Taylor et a1. 48-214 X Feldkirchner et al 48-214 US. Cl. X.R.