Catalysts and processes using them

Details Catalysts and processes using them Catalysts and processes using them

2000-11-17

2002-03-26

Richter, Johann (Department: 1621)

Chemistry: fischer-tropsch processes; or purification or recover

Group viii metal containing catalyst utilized for the...

C518S713000, C518S717000, C585S638000

Reexamination Certificate

active

06362239

ABSTRACT:

SUMMARY OF THE INVENTION
This invention relates to a process for the manufacture of, inter alia, alcohols and hydrocarbons from syngas, and to catalysts for use in the process. More especially, the invention provides a process in which molecules having two or more, especially four or more, carbon atoms are provided from carbon monoxide and hydrogen.
In Angew. Chem. Int., Ed. Eng., 15 (1976) 136, Henrici-Olivé and Olivé give a review of the early history of the Fischer-Tropsch synthesis and its commercial value. As stated in the article, the synthesis is versatile in that depending on the catalyst, temperature, and pressure, the process may be oriented to yield predominantly gaseous or liquid hydrocarbons, waxes, or alcohols as required, linear &agr;-olefins and linear alcohols being the initial reaction products. Depending on the catalyst and conditions, the predominant products vary. These may be, e.g., linear paraffins and alcohols, with branched isomers and other functionalities also being produced. Many of the products are valuable in themselves but the production of others, for example carbon dioxide, is generally to be avoided as far as possible.
A number of patents, for example U.S. Pat. Nos. 4,122,110, 4,291,126, 4,477,594, 4,562,174, and 4,659,742, describe processes for the manufacture of a mixture of alcohols of a molecular weight range that renders them suitable for addition to gasoline, in which various catalysts, usually containing copper, cobalt, an alkali or alkaline earth metal, and at least one further metallic element, are used.
At present, many fuels and other energy sources are transported over long distances in the form of gases or liquefied gas. Such transport is expensive, not least because of the safety measures necessary, including those relating to high pressures. A process that is efficiently (in terms of overall energy use) able to convert a gaseous energy source to a product that is at least partially liquid at ambient temperature or even up to 40° C., would be valuable, even if moderate pressure were required to maintain the product in liquid form. So also would any process that could efficiently convert an energy source that is readily transportable, e.g., a liquid hydrocarbon or coal, but which when burned is environmentally polluting, e.g., because of its sulphur content, by a step (e.g., syngas manufacture) which would enable the pollutant to be removed, before converting or re-converting it to a liquid organic material. Therefore the higher the weighted mean molecular weight of the product of such processes the more desirable the process.
There remains a need, accordingly, for a process in which the weighted mean of the range of molecular weights of the resulting organic materials is higher than that resulting from prior art processes, and preferably one in which the proportion of carbon dioxide formed is low.
BRIEF SUMMARY OF THE INVENTION
The present invention provides, in a first aspect, a process for the manufacture of organic materials, especially alcohols and olefins, from carbon monoxide and hydrogen which is carried out in the presence of a catalytic composition comprising a higher alcohol synthesis catalyst, at least one metallic element selected from the group consisting of magnesium and manganese, and, optionally, an alkali metal or alkaline earth metal, the catalyst being one obtainable by co-precipitation of its essential component metallic elements as oxalates. As higher alcohol synthesis catalyst there is advantageously used one comprising cobalt and copper, cobalt being the “Fischer-Tropsch” catalyst element and copper the “alcohol” element. It will be understood that in the catalyst the metallic elements may be in elemental form or they may be in the form of compounds, e.g., their oxides, or as mixtures of the metals in elemental form and compounds of the metals. By higher alcohols is meant a mixture of alcohols with molecular weights distributed over a range.
In a second aspect, the invention provides a process for the manufacture of a catalyst which comprises forming a solution of a cobalt salt, a copper salt, and a salt of at least one metal selected from manganese and magnesium, and co-precipitating the metals as oxalates from solution by the addition of oxalate ions.
The solvent is advantageously water, although an organic solvent, e.g., methanol, ethanol, acetone or a propanol or a butanol, may be used, if desired in admixture with water.
In a third aspect, the invention provides a catalyst comprising cobalt, copper, and manganese in atomic ratios of Co:Cu:Mn within the range 1:1 to 10:0.1 to 5. Advantageously, the catalyst contains at most 1% by weight of alkali metal. Advantageously, the ratios are in the range 1:1 to 5:0.15 to 3, more advantageously 1:1 to 5:0.2 to 3, and preferably 1:1 to 5:0.5 to 3, and most preferably 1:1:0.5 to 1. When the Co:Cu ratio is 1:1, and the Co:Mn ratio is 1:<1, the catalyst is advantageously one obtainable, and preferably obtained, by the second aspect process.
In a fourth aspect, the invention provides a catalyst comprising cobalt, copper, and magnesium in atomic ratios of Co:Cu:Mg within the range 1:1 to 10:0.1 to 10. Advantageously, the catalyst contains at most 1% of alkali metal. Advantageously, the ratios are in the range 1:1 to 10:0.15 to 10, more advantageously 1:3 to 7:0.5 to 5, and preferably about 1:4:2.5. When the Co:Cu ratio is 1:<2, and the Co:Mg ratio is 1:<1.5, the catalyst is advantageously one obtainable, and preferably obtained, by the second aspect process.
In a fifth aspect, the invention further provides a catalyst comprising cobalt, copper, and manganese in atomic ratios of Co:Cu:Mn within the ranges 1:1 to 10:0.1 to 5, or comprising cobalt, copper and magnesium in atomic ratios of 1:1 to 10:0.1 to 10, in which the molar proportion of the total cobalt and copper in the catalyst that is present in a mixed phase is at least 25%, advantageously at least 50%, and preferably at least 65%, and may be up to 95% or more.
In a sixth aspect, the invention provides a process for converting a carbonaceous energy source of a first type, e.g., a gas or liquefied gas, or one that is polluted, i.e., contains undesired components, especially sulphur, which comprises converting the source to synthesis gas (carbon monoxide and hydrogen) and then, in the presence of a catalyst according to the invention, or produced according to the invention, converting the synthesis gas to liquid or liquefiable alcohols and/or olefins. If the source of the first type is polluted, the process comprises removing the pollutant before converting or re-converting the energy source to liquid or liquefiable form.
DETAILED DESCRIPTION OF THE INVENTION
Advantageously, the process of the second aspect of the invention is used to make the catalysts of the third, fourth, and fifth aspects, and a catalyst of the third, fourth, or fifth aspect is advantageously used in the processes of the first and sixth aspects.
In a modification of the second aspect of the invention, presently not preferred, other low molecular weight organic acids, especially dibasic acids, may be used, if the relevant salts have a pK
S
value appropriate to ensure immediate simultaneous precipitation. Oxalic acid is preferred since it readily decomposes without leaving residues.
As indicated above, as higher alcohol synthesis catalyst there is preferably used one in which there are two metallic components, one of which is believed to be primarily responsible for the chain growth of the product, e.g., cobalt, iron, and ruthenium, and the other primarily responsible for alcohol formation, e.g., copper, palladium, rhodium, molybdenum, and chromium, although the invention is not to be regarded as limited by any theoretical considerations. It is believed, although again the invention is not to be regarded as limited by any theoretical considerations, that by co-precipitation of the oxalates of the two metals mixed phase materials are produced resulting in a catalyst with good selectivity to alcohols. This effect is surprising since, a

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