Activation of hydrocarbon synthesis catalysts with hydrogen...

Details Activation of hydrocarbon synthesis catalysts with hydrogen... Activation of hydrocarbon synthesis catalysts with hydrogen...

2000-01-04

2002-01-08

Richter, Johann (Department: 1621)

Chemistry: fischer-tropsch processes; or purification or recover

Group viii metal containing catalyst utilized for the...

Reexamination Certificate

active

06337353

ABSTRACT:

BACKGROUND OF THE DISCLOSURE
1. Field of the Invention
The invention relates to activating a hydrocarbon synthesis catalyst with hydrogen and ammonia. More particularly, the invention relates to forming an active hydrocarbon synthesis catalyst, including a Fischer-Tropsch type of hydrocarbon synthesis catalyst, by contacting a hydrocarbon synthesis catalyst precursor, comprising at least one catalytic metal component, with a reducing gas comprising a mixture of hydrogen and ammonia, at conditions effective to reduce the precursor and form an activated catalyst, and to a hydrocarbon synthesis process using the catalyst.
2. Background of the Disclosure
The synthesis of hydrocarbons, including oxygenated hydrocarbons such as methanol, from a synthesis gas comprising a mixture of H
2
and CO is well known. The synthesis gas feed is contacted with a Fischer-Tropsch catalyst at conditions effective for the H
2
and CO in the feed gas to react and form hydrocarbons. The synthesis is known as a Fischer-Tropsch hydrocarbon synthesis. Depending on the catalyst and conditions, the hydrocarbons may range from oxygenated compounds such as methanol and higher molecular weight alcohols, to high molecular weight paraffins which are waxy solids at room temperature. The process also makes, in lesser amounts, alkenes, aromatics, organic acids, ketones, aldehydes and esters. The synthesis is conducted in a fixed or fluidized catalyst bed reactor or in a liquid phase slurry reactor. Hydrocarbon synthesis catalysts are also well known and typically include a composite of at least one iron group catalytic metal component supported on, or composited with, with at least one inorganic refractory metal oxide support material, such as alumina, amorphous, silica-alumina, zeolites and the like. Various catalyst preparation methods have been used to form hydrocarbon synthesis catalysts, including impregnation, incipient wetness, compositing, ion exchange and other known techniques, to form a catalyst precursor. The precursor must be activated to form the catalyst. Typical activation methods include oxidation or calcination, followed by reduction in flowing hydrogen, multiple oxidation-reduction cycles and also reduction without prior oxidation. Examples of catalyst preparation and activation methods for Fischer-Tropsch hydrocarbon synthesis catalysts are disclosed in, for example, U.S. Pat. Nos. 4,086,262, 4,492,774 and 5,545,674.
SUMMARY OF THE INVENTION
The invention relates to forming an active hydrocarbon synthesis catalyst, including a Fischer-Tropsch type of hydrocarbon synthesis catalyst, by contacting a hydrocarbon synthesis catalyst precursor, comprising at least one catalytic metal component, with a reducing gas comprising a mixture of hydrogen and ammonia, at conditions of temperature and pressure effective to reduce the precursor and form an active catalyst, and to a hydrocarbon synthesis process using the activated catalyst. It has been found that forming the hydrocarbon synthesis catalyst by reducing the precursor, with a reducing gas comprising a mixture of hydrogen and ammonia, improves the properties of the resulting activated catalyst with respect to at least one of increased C
5+
selectivity, increased alpha (Schultz-Flory alpha) of the synthesis reaction and a reduction in methane make. These benefits are unexpected, in view of the fact that ammonia is a well known hydrocarbon synthesis catalyst poison. The catalyst precursor preferably comprises at least one catalytic metal component and at least one metal oxide catalyst support component.
The catalyst precursor may or may not be calcined prior to the reduction in the mixture of hydrogen and ammonia. The mixture of hydrogen and ammonia reducing gas may be substantialy comprised of hydrogen and ammonia or it may contain one or more diluent gasses which do not adversely effect or interfere with the activation, such as methane or argon and the like. The amount of ammonia present in the reducing gas will broadly range from 0.01 to 15 mole %, preferably 0.01 to 10 mole %, more preferably from 0.1 to 10 mole % and still more preferably from 0.5 to 7 mole %, based on the total gas composition. The hydrogen to ammonia mole ratio in the gas will range from 1000:1 to 5:1 and preferably from 200:1 to 10:1.
Thus, in one embodiment the invention is a process which comprises contacting a Fischer-Tropsch type of hydrocarbon synthesis catalyst precursor, comprising at least one catalytic metal component, and preferably at least one catalytic metal component and a metal oxide support type of component, with a reducing gas comprising a mixture of hydrogen and ammonia, at conditions effective to reduce the precursor and form an active catalyst. In another embodiment, the invention comprises a process for synthesizing hydrocarbons from a synthesis gas which comprises a mixture of H
2
and CO, wherein the synthesis gas contacts with a Fischer-Tropsch type of hydrocarbon synthesis catalyst, at reaction conditions effective for the H
2
and CO in the gas to react and form hydrocarbons and wherein the catalyst comprises a composite of at least one catalytic metal component and preferably also a metal oxide support component, and has been formed by contacting a catalyst precursor with a reducing gas comprising a mixture of hydrogen and ammonia, at conditions effective to reduce the precursor and form the catalyst. In a still further embodiment, at least a portion of the synthesized hydrocarbons are liquid at the synthesis reaction conditions. The conditions of temperature and pressure required to reduce the precursor and form a catalyst with a reducing gas comprising a mixture of hydrogen and ammonia in the practice of the invention, are the same conditions used for conventional hydrocarbon synthesis catalyst reduction and activation with hydrogen, in the absence of ammonia.
DETAILED DESCRIPTION
Hydrocarbon synthesis catalysts are well known and a typical Fischer-Tropsch hydrocarbon synthesis catalyst will comprise, for example, catalytically effective amounts of one or more Group VIII metal catalytic components such as Fe, Ni, Co and Ru. Preferably the catalyst comprises a supported catalyst, wherein the one or more support components of the catalyst will comprise an inorganic refractory metal oxide. The metal oxide support component is preferably one which is difficult to reduce, such an oxide of one or more metals of Groups III, IV, V, VI, and VII. The metal Groups referred to herein are those found in the Sargent-Welch Periodic Table of the Elements,© 1968. Typical support components include one or more of alumina, silica, and amorphous and crystalline aluminosilicates, such as zeolites. Particularly preferred support components are the Group IVB metal oxides, especially those having a surface area of 100 m
2
/g or less and even 70 m
2
/g or less. These support components may, in turn, be supported on one or more support materials. Titania, and particularly rutile titania, is a preferred support component, especially when the catalyst contains a cobalt catalytic component. Titania is a useful component, particularly when employing a slurry hydrocarbon synthesis process, in which higher molecular weight, primarily paraffinic liquid hydrocarbon products are desired. In some cases in which the catalyst comprises catalytically effective amounts of Co, it will also comprise one or more components or compounds of Re, Ru, Fe, Ni, Th, Zr, Hf, U, Mg and La, some of which are effective as promoters. A combination of Co and Ru is often preferred. Useful catalysts and their preparation are known and illustrative, but nonlimiting examples may be found, for example, in U.S. Pat. Nos. 4,568,663; 4,663,305; 4,542,122; 4,621,072 and 5,545,674.
The catalyst precursor is prepared by any convenient and known method, such as impregnation, incipient wetness, ion exchange, kneading, precipitation or coprecipitation, melt deposition or any other known compositing techniques. The catalytic metal component is typically applied as a solution of a compound of the metal that dec

Affiliated with

Also associated with

Rating

Activation of hydrocarbon synthesis catalysts with hydrogen... does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Activation of hydrocarbon synthesis catalysts with hydrogen..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Activation of hydrocarbon synthesis catalysts with hydrogen... will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-2835657