DE1000362B - Process for the hydrogenation of carbons using copper-containing melting and sintering catalysts - Google Patents

Description

Process for carbohydrate hydrogenation using copper-containing Melting and Sintering Catalysts There is already a process for the hydrogenation of caroxides at temperatures of 150 to 350 °, preferably 180 to 270 °, and pressures of i up to 200 at, preferably 10 to 50 at, in the presence of particularly active iron, Melting and sintering catalysts, which optionally contain the usual activators, has been proposed. It is characteristic of this procedure that the used Catalysts have a copper content of at least 5%, based on the iron present, have and that their reduction and formation at temperatures below 350 °, preferably below 300 °. Hydrogen and / or carbon oxides are expedient for this purpose High velocity gases of over 50 cm / sec, preferably over rao cm / sec, applied.

The high copper content allows for this proposal, in contrast too sooner, the reduction and formation at low temperature below 350 ° in the synthesis furnace itself. It is to be regarded as particularly advantageous that such Catalysts show no shrinkage in this operation, the reason for formation of cavities and channels in reactors, which for example are equipped with pipes are, could go. Fixed melt catalysts can be used in synthesis furnaces can be used with pipe lengths of, for example, 10 to 25 m.

Their diameter can be over 10 mm, advantageously over 30 mm.

For the production of the catalysts, iron, advantageously in metallic form, is used In the form or in the form of oxide, especially the trivalent form, copper is expedient used as an oxide of mono- or bivalent copper. In many cases it is favorable, some of the metals in the form of salts with oxidizing properties, z. B. as nitrites, nitrates or perborates, to be used, especially if the metal present proportion is large.

This is used as the starting material for sintered catalysts Iron and copper are particularly useful in the form of a powder that is as fine as possible Grain size of less than 100 µ, preferably less than 10 µ, related.

The amount of alkali added to the catalyst is about 1 to 4%, based on iron. The proportion of oxygen-containing compounds formed, before especially high molecular weight compounds, is not insignificantly lower here.

It has now been found that the method described at the outset for Hydrogenation of carbohydrates is particularly suitable for those containing oxygen and high molecular weight compounds, preferably on esters, can be carried out if the Catalysts more than 20%. preferably more than 25%. Copper and more than 4 ° / o Alkali, calculated as K2 O, preferably 6 to 10%, based on what is present Iron, and the content of metallic iron after reduction or formation is at least 80%, based on the total iron.

The compounds obtained in the synthesis include usually Temperature all three states of aggregation: gaseous gasols, the bulk of the liquid ones Hydrocarbons and alcohols and the solid high molecular weight hydrocarbons.

Valuable low molecular weight alcohols are contained in the water of reaction. Of greatest practical interest is the composition of the main product of the liquid hydrocarbons and alcohols. The increased alkali content of the catalysts allows depending on their manufacturing conditions and the type of alkali addition extensive specialization of these synthesis products.

For a short time, for example at 350 °, but also at lower temperatures fully reduced melting and sintering catalysts, d. H. those with a reduction value over 80% of the iron and with a high copper and alkali content of more than 4% K2O, based on the iron present, cause the formation from above to an increased extent 320 ° boiling oxygen-containing compounds in which the ester component has a represents a very high percentage of the total product, e.g. B. above25, preferably above 35 percent by weight, and compared to the proportion in alcohols considerably predominates; in addition, the entire proportion of those boiling above 320 ° is reached Products a surprising amount for melting and sintering catalysts of more than 25 "/ o. In the fraction 30 to 180 ° predominate in the oxygen-containing products the alcohols. In the fraction 180 to 320 ° is the ester portion about 20 to 30 percent by weight and is therefore almost always higher than the proportion of Alcohols.

If the alkaline component is used in melt catalysts instead of z. B. added as K Q H or K2 C 03 in the form of, for example, potassium silicate, so the formation of high molecular weight hydrocarbons increases at the expense of the ester component.

Due to the increased amounts of alkali, it became unpredictable enables further reduction of the reduction times. While with the previously known Process reduction times of about 4 to 6 hours can be achieved now shorten the reduction times to about 2 to 3 hours when at temperatures is reduced or formed by 300 to 350 ° and reduction values of 80 ° / o and higher should be achieved.

The extraordinary mechanical strength of the invention Catalysts and their low tendency to deposit carbon make them in Corresponding grain size (e.g. 20 to 200 µ) for use in »fluidized bed synthesis« suitable.

Their use is in the powdery as well as in the granular state possible in the case of carbohydrate hydrogenation in the liquid phase, especially in the oil phase.

However, their use in granular form is particularly advantageous, z. B. at 0.5 to 6 mm, preferably 1 to 3 mm in a fixed form, for example in pipes up to about 25 m in length, which have a diameter of about ru to 100 cm, preferably from 30 to 70 cm.

Example i 1000 g of a mixture consisting of Fe2O3 (polishing red), Cu O and potassium carbonate, in which the proportions Fe: Cu: KgO are 100: 25 : 8 behave, are melted with the supply of oxygen. The melting temperature of the mixture was about 1600 °. Fe2O3 and CuO had a grain size of about i to 3 or 18 µ.

After the melt had cooled down, the melt cake was crushed, namely to a grain size between i and 2 mm. The reduction was done with a Mixture of 75% H2 and 25% N2 with a gas velocity of 1.5 m / sec (normal conditions) at 350 ° for 2 hours. Thereafter, the reduction value was about 100%.

This catalyst was placed in a double tube furnace, which has an annulus of 24 # 44 cm, filled and with finely purified water gas at a synthesis pressure operated from 20 atü in a single pass, a CO conversion of 81% was achieved at 207 ° (CO + H2 conversion = 61.5%) achieved. The composition of the liquid primary products was as follows:> 320 ° .............. 26.2 percent by weight 320 to 180 ° ................ 25, 8 percent by weight 30 to 18o ° ......., ..., 48, o percent by weight The proportion of aliphatic esters was about 40% in the highest fraction, in the middle Fraction about 25%, in the gasoline fraction about 10%. The corresponding proportions of alcohols were: 2, ro and 33%, respectively.

Consists of a normal ammonia synthesis catalyst when using from about 6% Fe as well as small amounts of Al2O3, SiO2 etc., was under the same Synthesis conditions requires a synthesis temperature higher by 12 ° to achieve the same To achieve sales. The yield of boiling over 320 ° Connections was under 19%, the ester content of this fraction was about 20 "/ o.

Example 2 A catalyst was prepared according to Example i, of (instead of 80 / o) 5, 2% K2O and, based on iron, ru parts of ZnO (grain size approx 1 µ) also contained. With reduction and synthesis conditions as in the example i was found: CO conversion 81.5%, CO + H2 conversion 63%, synthesis temperature 207 °. The synthesis product consisted of 28% of substances boiling above 320 °, between 180 and 320 °, 26% was present, and the remainder boiled between 30 and r80 °. The ester portion in the high-boiling fraction was 25%, in the diesel oil fraction 22%, in the petrol fraction at 13%.

The corresponding alcohol proportions were 10, 22 and 30%, respectively.

Was this catalyst in a synthesis furnace of 5 m length (pipe diameter 14 mm) at 250 ° with a gas mixture containing 75 "/ o IL for 30 hours (Reduction value 85 ° / Q) and then proceeded to synthesis under the above conditions, the following were obtained: CO conversion 84%, CO O + H2 conversion 63%, synthesis temperature 231 °.

(With a reduction time of 48 hours, the synthesis temperature could be lowered to 225 °.) The resulting liquid products showed a similar one Composition as above.

Example 3 A mixture consisting of Fe2O3, CuO (grain size of Fe2O3 about 3 µ, of the CuO about 2 µ) and K2CO3 in the ratio 100: 25: 5 as Fe: Cu: Calculating K2O, it was made into a paste with a little water at 100 to 120 ° dried for 5 hours and with the addition of air at a temperature sintered at 1150 ° for 60 minutes. The cooled mass was crushed and on a Grain size between i and 2 mm screened off.

The grain was also reduced at 350 ° for 120 minutes a mixture consisting of 75% H2 and 25 / 0.Ng, at normal pressure, the linear Gas speed was 1.5 m / sec. The reduction value of the reduced catalyst was 80%.

Was this catalyst at a synthesis pressure of 20 atü with water gas operated in a single pass, a CO + H2 conversion of 61% was observed at 215 °. The gas loading was 200 liters / liter of catalyst / hour. The resulting liquid Product contained 29% fractions boiling above 320 °, the fraction was 180 to 32o ° 20 ° / a, the fraction 30 to 180 ° 51%. The proportion of esters in the high-boiling fraction was 45 / &, in the diesel oil fraction 33%, in the gasoline fraction 11%. The alcohol content were r, 5 and 35e / o, respectively.

Was the same catalyst while at 250 ° in a synthesis oven Likewise reduced with H2 / N2 for 30 hours (reduction value 82e / o), the CO + H2 conversion was then under the same conditions as above 63% at a temperature of 230 °. In the accumulated liquid product was both the proportion of high-boiling Products as well as the proportion of oxygen-containing compounds decreased somewhat.

Example 4 An aqueous solution containing 40 g Fe and ru g Cu in the form of nitrates per liter became hot too one also called Solution of 100 g of soda in 1 liter of water. Here the quantities were measured in such a way that that the pjj value after the precipitation was about 7 to 7.2. The precipitated contact mass was filtered hot until about 0.5 g residual alkali, based on zoo g iron, washed out and divided into two parts.

The first part was so impregnated with KOH that there were 100 parts Iron 6 parts, calculated as K20, were omitted. The second part was made with potash water glass Impregnated in such a way that for every 100 parts of Fe 5 parts, calculated as K2O, and 25 parts SiO2 was omitted. The moist mass was dried at about 120 °.

The two masses were separated from each other at about 1500 ° Supply of air as an oxidizing agent melted. The melt obtained was comminuted and sieved to a grain size between 1 and 2.5 mm. The undergrain and the dust can be added again to a new melt.

The reduction took place at 350 ° for 12 minutes with a mixture Consisting of 75% H2 and 25 "A Ng. The reduction values were above 85% iron, based on total iron.

Became the catalyst impregnated with KOH using water gas as synthesis gas at a pressure of 20 atü, a load of 200 volume gas / vol. Catalyst brought to reaction at 210 °, a CO + H2 conversion of 63% was observed. The resulting liquid product contained 28% boiling above 320 ° Ingredients with 41% esters and a little alcohol. In the fraction 180 to 320 ° 29 per cent were esters and 10 per cent alcohols; in the fraction 30 to 18o there were about 30 per cent Alcohols and 8% esters present. There were also small amounts in all of the factions present in ketones, aldehydes and acids.

When using a cycle (cycle ratio 1 + 2) increased under the above conditions, both the yield of high molecular weight Compounds somewhat (to 31%), and there was also a certain increase in oxygen-containing compounds Connections a.

With a reduction of this catalyst at 240 ° with a gas, consisting from 27% CO, 52% H2, Balance inert, using a linear gas velocity of 1.3 m / sec under normal conditions, 24 hours were required. The reduction value was then over 80%. The proportion of high molecular weight compounds (> 320 °) increased still by 3%, the proportion of oxygen-containing compounds went in favor of olefins something back.

The second catalyst, under the same conditions as above reduced, gave one in all three experiments under the same synthesis conditions Increase in the yield of products with a boiling point above 320 °. Corresponding the proportion of parliamentary groups from 30 to 180 ° fell.

The yield of oxygen-containing compounds was also in all of them Parliamentary groups to determine a waste.

Claims (1)

PATENT CLAIM: Process for the hydrogenation of carbohydrates at temperatures from 150 to 300 °, preferably from 180 to 270 °, at pressures from 1 to 200 at, preferably zo to 50 at, using fused and sintered iron catalysts with a Addition of at least 5% Cu, based on the iron present, at temperatures have been reduced or formed below 350 °, preferably below 300 °, thereby characterized in that the catalysts for the purpose of obtaining synthesis products with increased proportions of high molecular weight oxygen-containing products, in particular Esters, more than 20%, preferably more than 25% Cu, and more than 4% alkali, calculated as K20, preferably 6 to 10%, in each case based on the iron present, and the content of metallic iron after reduction or formation at least 80%, based on the total iron and determined as a reduction value, amounts to. Documents considered: French patent specification No. 841 043; Journal of the Society of Chemical Industry of Japan, 42 (1939) pp. 107 B ff.