US1502336A - Method of making catalyst - Google Patents

Description

proved atented July 22, 1924.

UNITED STATES 1,502,336 PATENT OFFICE.

LUIGI oAsALE, or some, ITALY, assrenoa 'ro CASALE mom comm, or

. memo, swrrznarm.

METHOD 0]? MAKING CATALYST.

No Drawing.

To all whom it may concem:

Be it known that I, LUIGI OAsALn, a citizen of the United States, and residing at Rome, Italy, have invented a new and Im- Method of Making Catalyst, of which the following specification is a full disclosure.

This invention deals with the preparation of so-called catalytic material suitable for accomplishing the formation of ammonia by causing hydrogen and nitrogen to combine when subjected, under appropriate conditions, to the action of the catalyst. Various substances are known to possess catalytic properties of this nature but commerclal considerations demand the use of inexpensive ingredients and likewise require that the method employed for im-.

partin catalytic properties to the material used s all be not only an inexpensive and easily performed method but also shall produce great catal tic efficiency.

Iron, either a one or with other elements, has heretofore been ascertained to be a satisfactory catalyst but its catalytic effectivity has varied widely in accordance with the procedure adopted for its preparation. Iron is initially obtainable only in association with certain impurities having a detrimental influence on the catalytic activity. These so-called poisons include such elements as sulphur, phosphorus, arsenic, etc., and, to eliminate them, has been one of the problems confronted by the art. The

" prior methods most nearly meeting commercial considerations have involved, as a step, the use of oxygen gas for oxidizing the iron; the material beingsubjected to a stream of the gas under moderate condi- 40 tions under which the iron or its oxide has been brought as high as the point of fusion. The mass was then allowed to cool and solidify and subsequently was reduced in hydrogen gas. It was found that, by starting with sufficiently pure iron, catalytic properties could be imparted tothe iron.

This invention is based upon the discovery that if the oxidation be carried out under conditions of extreme violence, in-

stead of moderately as heretofore, that a ronounced improvement would be realized 1n the catalytic activity of the ultimate product. That is to say this invention proposes not merely to employ oxygen gas in sufficient quantities to oxidize the material Application filed August 22, 1923. Serial No. 658,828.

and bring it into a condition of fusion, but to carry out the oxidation with such exceed ng rapidity and simultaneity as to all part1cles of the material, that the heat engendered will produce not only a fusion of the entire mass but will attain a tem perature greatly in excess of the fusion point; so much as to rise to the vaporizat1on point and cause the material to boil so violently that much of it escapes in a cloud of vapor carrying away the above mentioned poisons in vaporous form. It is would assume an allotropic state, especially active, and this might play an important part in determining catalytic activity. As an illustration of the radical treatment characterizing this step of the process, itmay be explained that the oxygen gas is to be supplied, not in the form of a moderate stream, but as a powerful blast, i. e., in such overwhelming quantities as would be delivered by a nozzle say of 6 cm. in diameter under a gas pressure of about 10 atmospheres and projecting the jet of gas either against or through a moderate amount of the material say 5 or 6 kg. It will be understood, of course, that the combustion will be initiated in any suitable manner, as by an igniter such as the flame of a Bunsen burner, and forthwith the oxidizable ingredients in the material will spontaneously take fire and burn (oxidize) with almost explosive violence; the entire interval of complete oxidization being almost instantaneous and under such excessive temperature conditions(about 2,000 O.) that from 10 to 20% of the entire mass will be volatilized and all so-called poisons will likewise be volatilized and swept away in the rush of escaping ,gases. It has been demonstrated by exhaustlve commercial tests that this treatment, as a step in imparting catalytic properties to iron containing material, is extremely effective and may be resorted to successfully whether the material treated be virtually pure or whether it contains considerable quantities of poisonous elements, or whether it contains additional elements having also catalytic or beneficial characteristics. One distinct advantage of this excessively high temperature treatment, as an oxidizing step, is that it renderss the oxidized product entirely homogeneous as to the distribution throughout its mass of probable that at or above 2000 C. the iron the various elements remaining thereinand,*

' accordingly, when the mass is subsequently broken into small pieces and when these are subsequently reduced by hydrogen, each of the resultant subdivisions of the catalyst are alike in composition and are equally effective in a catalytic sense; a result that has heretofore been unattainable by the pre-' 'vious moderate conditions of oxidation which merely produced what may be termed an incipient fusion of the mass. I

This invention, accordingly, contemplates a process of preparing a catalyst by first subjecting the material to an excessively intense heat such as will quickly volatilize a considerable proportion of the entire mass including especlally such poisons as sulphur, arsenic,phosphorus and the like and which will, by virtue of the violent ebullition of mix together all of the remaining ingredients or elements so as to produce a thoroughly homogeneous mixture of oxides. -VVhen subsequently reduced by the action of hydrogen, in any appropriate manner, the resultant product will be rendered highly catalytic. This subsequent step may be performed by passing hydrogen through the.

broken up material in a separate container and the resultant catalyst may then be placed in the catalyzing tube of the ammonia forming apparatus, or, the broken-up oxidized material maybe placed directly in the catalyzing tube and the hydrogen may be passed through such tube until the reduction has been completed; whereupon the resultant catalytic material will continuethereafter to cause the hydrogen and nitrogen passing through the tube to be combined to form a.) ammonia.

Various materials, or mixtures of ingredients, maybe initially subjected to the intense oxidizing treatment. It'is not essential to start with practically pure metals although the treatmentis successful with pure metals. Traces of sulphur, phosphorus and the like are not only unobje'ctionable' but even are advantageous in the sense that theirv combustion assists in creating the excessively intense heat which is essential and these poisons escape, as aforesaid, in vaporous form.

Even iron that has, through prolonged use as a catalyst, become poisoned and has lost its catalytic properties, may be restored to its original activity by intensive treatment. In t at case, it is desirable to mix the poisoned catalyst with some material possessing a high heat of com'- bustion, as for example, carbon or even ordinary coal. Under the violent blast of oxygen the iron and the coal in the mass will oxidize violently and the whole mass will be brought to the intense tem erature above described and will be rendere homogeneous the fused mass, thoroughlyv and uniformly duce the results-herein set metals of the iron as proved by experience,

resorting to this 1 will be found to be restored (when subsequently reduced) fully to its original catalytic powers.

Further investigations have also demonstrated'that it is desirable to carry out the aforesaid violent oxidation in the presence of certain other elements, the oxides of which are irreducible by means of hydrogen; theseelements being, for example, alkali metal oxides, alkali earth-metal oxides such as calcium oxide and also oxides of magnesium, aluminum and the like. These irreducible oxides, in this process, and by the reason of the high temperature thereof are dissolved inthe fused mass and may be employed beneficially to the amount of over 10% and form a thoroughly homogeneous mixture with the iron oxide so that in the ultimate catalyst, they increase the surface of the mass and, accordingly, increase the exposure of'thecatalytic material to the hydrogen and nitrogen in the process of forming the ammoma.

Magnesium, titanium,

aluminum, calcium, ferronese, ferro-silicon and iron pyrites possess high heats of combustion and consequently may be advantageously employed to facilitate the extremely excessive temperatures which, as aforesaid, are indispensable for the product of a good catalyst. When these are employed, it becomes possible to utilize artificial or natural iron oxides, or oxides of metals belonging to the iron group, or compounds yielding iron, inasmuch as the intense heat generated by the oxidation under the powerful blast of oxygen of the firstmentioned combustible materials will proforth thereby in a most efiicient manner utilizing certain irreducible oxides which have the power of enhancing the catalytic capacity of iron. and metals belonging to the iron group.

These oxides capable of increasing the catalytic activity of the iron and other group may be used as such, mixed with the oxides of said metals, but it may also be suitable to use instead of them the metals they are obtained from, which metals having avery high oxidation heat facilitate the obtainment of those very high temperatures which are indispensable, for producing a good catalyst.

A convenient method of carrying out the oxidation in a practical way is to line a suitable crucible, as of cast iron, with powdered iron oxide obtained by a previous performance of the process. This powdered iron oxide may be mixed with calcined dolomite and the crucible may be lined by first covering its bottom with a layer of the mix ture. A tube of sheet iron may then be set on the lined bottom and the mixture. 130

used for the lining may then be packed and compressed in the annular space between the sheet iron tube and the wall of the crucible. This provides a receiver in the nature of a lined crucible.

Within the central chamber is placed the material to be oxidized which may either be a mixture of iron oxide and coal containing additions of predetermined quantities of aluminum, calclum, magnesium and the like; if desirable in elemental form. Or, in the central chamber may placed the iron together with weighed quantities of the irreducible oxides, or substances easily converted to same, such as bauxite, magnesia, lime, dolomite and the like, which it is desired to have dissolved in the ultimate fused iron oxide. Or, any other of the materials herein mentioned may be placed in a central chamber. The oxidation is then carried out by the powerful blast of oxygen, as aforesaid.

This process will, therefore, be perceived to be entirely satisfactory for converting various sources of iron into catalytic material. Ordinary iron or steel turnings or filings produced as waste by machine shops may be employed, or native iron ore such as magnetite may be used, and likewise, old waste catalytic material which has become poisoned may be restored to its original activity.

I claim:

1. A catalyst-preparing process wherein, as a purifying step, the impure mixture of oxides is subjected to a temperature so far exceeding the melting point of the mixture as to vaporize not only a considerable proportion of the useful oxides but also all elements in the nature of poisons capable, if remaining in the ultimate product, of exercising a detrimental effect on its catalytic properties.

2. The operation of preparing a mixture of oxides suitable for subse uent reduction by hydrogen to a catalyst w ich consists in subjecting an ignited metal-containing mixture to a powerful blast of oxygen to produce a confiagration of the mass so intense that its temperature will greatly exceed the melting point and cause not only a violent boiling of the melted material and thereby intimately and uniformly mix its residual ingredients but also cause all the detrimental substances to be vaporized and driven off as such.

3. A method of making a catalyst of oxide-containing material consisting in first mixing the same with a readily oxidizable substance to produce a-'mixture capable of' rapid combustion, then subjecting said ignited combustible mixture to a powerful blast of oxygen to develop a temperature of about 2000 C., then allowing the mass to cool; then breaking it into fragments; and then subjecting said fra ments at an elevated temperature to hy rogen to develop catalytic properties. v

4. The art of roducing a homogeneous catalyst composed of a highly active metal and an intimately associated compound irreducible by hydrogen for increasing the active surface of the catalyst, said art consisting in subjecting an easily-oxidizable mixture containing said metal and an element of said compound to a powerful blast of compressed oxygen to roduce a violent and rapid confiagration 0 said mixture at a temperature -adequate to cause an extremel vigorous ebullition of the melted metalllc oxides to dissolve and uniformly distribute therein all residual oxides irreducible by hydrogen and to volatilize and dissipate as a vapor all elements detr1 mental to catalytic activit then permitting the purified molten oxldes to cool; and then fragmentizing and reducing the same by a mixture of nitrogen and hydrogen.

In witness whereof, I hereunto subscribe my name, as attested by the two subscribing witnesses.

LUIGI CASALE. Witnesses:

REUN Lnrnx'rz, W. E. BANN.