DE954987C - Process for the desulphurization of petroleum hydrocarbons - Google Patents

Description

Process for the desulphurization of petroleum hydrocarbons The invention relates to a process for the desulfurization of petroleum hydrocarbons according to the Hydrofining or attofining processes in the presence of catalysts. Particularly effective for these purposes are catalysts containing cobalt and molybdenum, often in the form of cobalt molybdate, but often also with a cobalt or (preferably) Excess molybdenum oxide. Such catalysts are generally used in such a way that that the cobalt and molybdenum compounds on a porous carrier such as activated Bauxite or aluminum oxide. The carrier not only increases activity a given amount of cobalt and molybdenum by increasing the surface area, but rather can also contribute significantly to the particular type of catalyst activity. is the carrier, for example bauxite or aluminum oxide, accelerates together with cobalt and / or molybdenum. the dehydration of naphthenic carbons in the material to be desulfurized. The hydrogen formed in this way is advantageously liable used for the desulfurization reaction.

With low cobalt and molybdenum contents the generally increases Catalyst activity with increasing cobalt and / or molybdenum content; becomes the total salary but if cobalt and molybdenum are increased further, cobalt and molybdenum increases Molybdenum additives make the catalyst activity less and less until they are above one certain content becomes constant or if the cobalt and / or molybdenum addition is increased further even sinks.

If activated aluminum oxide is used as a carrier, it increases the activity ceases when the cobalt, expressed as CoO, is above 3% of the catalyst while it continues to increase with molybdenum content, expressed as MoOs, until the molybdenum content amounts to 150 / o of the catalyst and hardly changes, when the molybdenum content (as MoO3) is increased to 25 0 / o. Because molybdenum and cobalt are relatively expensive, it is usually convenient to keep the cobalt and molybdenum levels to keep among those in whom optimal activity is obtained as an additional Activity above this point only with a substantial cost of additional cobalt and molybdenum can be obtained.

The activity for certain cobalt and molybdenum contents depends on a given aluminum oxide with cobalt (as CoO) and molybdenum (as MoO3) contents together not more than 18%, but little of the manner in which the cobalt is introduced and molybdenum into the aluminum oxide, if only they are evenly distributed. If For example, cobalt and molybdenum are precipitated from the solution with the aluminum oxide or as a solution for wetting aluminum oxide gel, which is then dried is used, or dried, roasted activated. Aluminum oxide with the Solution is impregnated is indifferent; the catalyst obtained has after Drying and roasting, e.g. B. at 5500, about the same activity. At over I80 / o Cobalt and molybdenum content (expressed as Co 0 and MoO3) make it difficult to use catalysts produce by the impregnation process, and it must be the co-precipitation be applied. However, as has already been stated, it results in up to one Molybdenum content of 25% MoO3 only shows a slight increase in activity.

If, on the other hand, a bauxite is used instead of pure aluminum oxide, there are significant differences in activity depending on the cobalt and molybdenum content on. In this case are naturally precipitated together or in a similar manner Catalysts produced are excluded, and only those produced by impregnation are produced Investigated catalysts. With the same cobalt and molybdenum content, low Cobalt and molybdenum contents the catalyst activity of a certain bauxite support higher than that of an activated alumina carrier.

As the molybdenum content increases, so does the. Bauxite carrier first and then falls, so that a catalyst with 140 / o Mo O3 is less active as a catalyst -with 7% MoO3 on the same bauxite support. The latter catalyst has a far superior activity compared to catalysts with activated aluminum and is also more active than those containing 25% MoO3, and noticeably better than those with 11% MoO3.

Bauxite as a catalyst support is well known, and when the bauxites Only as effective as the aluminum oxides would the use of bauxite be Worthwhile because of the much lower price. Certain bauxites are now less effective as a carrier .all alumina, especially for catalysts, such as interest you here.

In the United States patent specification 2487 466 - it is stated that a cobalt and molybdenum oxide catalyst on a bauxite support on which more than 5% aluminum oxide are distributed, more effective and, because of the high bauxite content, cheaper than the same composite catalyst on an alumina support. The examples show that the - bauxite in itself as a catalyst carrier is less effective than aluminum oxide. This may be due to the fact that in these cases it is the only catalyst support bauxite used was not of the type used in accordance with the invention.

It has been found that in a process for the desulfurization of Petroleum hydrocarbons, preferably according to the hydrofining or autofining process, in the presence of catalysts consisting of a mixture or chemical compounds from cobalt and molybdenum oxides or from a mixture of one or both oxides with such a compound on a bauxite trihydrate carrier, especially those catalysts are suitable, their bauxite trihydrate carrier at least 2 hours has been heated to 550 ° and then a surface area of more than 120 to 1215 qm / g, measured according to the nitrogen adsorption method of Brunauer, Emmett and Teller (see.

Journal of the American Chemical Society 1938, vol. 60, p. 309) and I to I5, preferably 5 to 12 percent by weight MoO3 and 0.2 to 3, preferably Contain 2.5 percent by weight of Co 0.

The bauxites effective in the process of the invention are trihydrate bauxites of the general formula Al2 O3 3 H2 0 (excluding impurities). Monohydrate bauxites of the general formula Al203 H2 H2O are ineffective as carriers.

The activity of the catalysts used is the same or better than that of a catalyst on an alumina support with greatly reduced Cobalt and molybdenum content. The catalysts used according to the invention are cheaper than the aluminum oxide containing catalysts, once because of the cheapness of bauxite and, on the other hand, because of the savings in metal costs.

Although the bauxite-based catalysts are about 200/0 larger Density than those based on alumina, so that a certain volume of a bauxite catalyst 20 o more molybdenum than an equal volume of an aluminum oxide catalyst has, this factor plays a subordinate role compared to the advantage of increased activity in the bauxite catalysts according to the invention.

The optimal cobalt content as Co 0 on an aluminum oxide support is about 2 percent by weight of the catalyst. With such a cobalt content the activity of a bauxite catalyst is superior to that of an aluminum oxide catalyst, when the molybdenum content, expressed as MoO3, is less than 10 percent by weight. The same generalization applies to catalysts based on bauxite and aluminum oxide, equal amounts of cobalt and molybdenum by weight per unit volume of catalyst contain. At the optimal range of the molybdenum content of a bauxite catalyst activities are achieved which correspond to those of the most effective aluminum catalysts with much larger molybdenum contents. This is how it is when using a selected bauxite as a carrier and careful selection of the molybdenum content possible, to achieve an activity equal to or greater than that of an alumina catalyst at significantly reduced costs, since less molybdenum and bauxite are required cheaper than activated alumina.

The greater effectiveness of trihydrate bauxite compared to monohydrate bauxite likes due to the larger cavities and the larger internal surface area involved in expelling a larger amount of water can be explained without this presumed Explanation of a limitation of the invention should be made.

Five trihydrate bauxites (two from the Gold Coast, one each from India and British Guiana and one from the Far East) are used as carriers for 7 e / o Mo 03 and 2% Co 0 and are all found to be more effective as a catalyst on an aluminum oxide carrier with 11% MoO3 and 2.3% CoO. Three monohydrate bauxites (two of French and one of Dutch origin) are ineffective as carriers.

It is not to be assumed that the increased activity of catalysts on trihydrate bauxite basls with the specified surface area necessarily and is due solely to the surface characteristics. That's how it has Aluminum oxide with its larger surface area forms the carrier of the catalyst lower activity than the bauxite supplying the catalysts according to the invention. However, it has been found that when a bauxite is used to make a catalyst used wi.rd, the activity of which is greater than that of an aluminum oxide catalyst with a corresponding cobalt and molybdenum content of 1 to 1.5% and 5 to 12%, its surface area after drainage must be greater than 120 to I25 m2 / g.

The following examples show the effectiveness of the trihydrate bauxite described in detail.

Example I Samples of a number of bauxites are taken through two hour Roast dehydrated at 5500; cooled in the absence of moisture and weight loss certainly. 200g of each dehydrated bauxite are then used to make the catalyst used according to the invention. In each case, 1.5 hours at 300 with 300 ml of a solution containing 66 g of ammonium molybdate, (NH4) 6Mo7O24 # 4 H2O, and 56.4 g Cobalt nitrate, Co (NO3) 2 # 6H2O, in 127.5 g of distilled water and 134.2 g of aqueous Ammonia solution (specific gravity 0.88) impregnated, filtered off, 64 hours dried at 1500 and finally roasted at 5500 for 2 hours.

The activities of these catalysts are compared in the desulphurization of a gas oil treated for 2 hours at a total pressure of 4.5 kg / cm2 and 404 ° in the presence of hydrogen supplied in an amount of 26.8 m3 / m3. The results obtained can be seen from the following table. The activities are expressed as a percentage of that of a catalyst whose activity is arbitrarily set at 100. Weight loss when analyzing surface Desulfurization Origin of the bauxite Type of bauxite of the catalyst Size according to the Drainage activity in% drainage CoO MoO3 Holland ................... 14.0 monohydrate 1.45 6.6 - 38 France ................ 12.0 - 1.1 4.15 - 25 France ................ 16.2 - 1.0 4.6 - 34 British Guiana ............ 30.8 trihydrate 2.4 9.1 125 100 Gold Coast .................. 30.4 - 2.25 10.1 172 106 Far East ............... 30.0 - 1.85 8.1 134 92 Gold Coast .................. 31.0 - 2.3 8.4 157 96 India ..................... 31.0 - 2.0 8.5 141 100 India ..................... - - 1.44 7.2 117 70 The activities of the alumina basic catalysts compared to the assumed value of 100 are listed below. Catalyst analysis Desulfurization activity CoO MoO3 1.6 4.4 70 2.2 7.8 85 The catalysts described above can advantageously be used for carrying out the autofining process on crude oil, as described in the earlier German patent applications p 46867 IVd / 23b, p 443I3 IVd / 23b, A 996 IVd / 23b and A5oI4IVd / 23b and the British Patents 654 152, 669 536, 663 038 and 669 553. In this process, a bauxite-based catalyst with only 7% molybdenum as Mo O3 has a greater activity than an alumina-based catalyst with the same molybdenum content and approximately the same activity as an alumina-based catalyst with 25% molybdenum.

Example 2 A number of bauxite based catalysts and a Aluminum oxide based catalysts are produced as follows: 330 g ammonium molybdate, (NH4) 6Mo7O24 # 4H2O, are dissolved in 500 g of distilled water and 88 g of an aqueous Dissolved ammonia solution (specific gravity 0.88). This solution becomes 282 g of a solution of 2821g cobalt nitrate hexahydrate, Co (NO3) 2 6 H2 O, in 100 g distilled Given water. This solution is poured onto 1640 g of an Indian bauxite which previously activated by heating to 5500 for two hours, and the bauxite for 2 hours impregnated with this solution.

After the impregnation, the bauxite is removed, 16 hours at I500 dried and roasted at 5500 for 2 hours. Analysis reveals a cobalt content as Co 0 of 2 percent by weight and a molybdenum content, as Mo O3 of 8.5 percent by weight. Higher cobalt and molybdenum contents are reduced by multiple impregnation Contents by reducing the cobalt and molybdenum content of the impregnation solutions obtain.

Another high molybdenum alumina catalyst is used produced by cobalt and molybdenum together with the aluminum oxide in the manufacture of alumina gel. This gel is made accordingly dried and roasted before use.

These catalysts are used to remove sulfur from an Iranian gas oil by the autofining process. The gas oil with a specific gravity of 0.8635 at 15.560 initially contains 1.14% organically bound sulfur and has a boiling range of 256 to 357 ° in Engler distillation. The catalyst charge in each case takes up a space of 520 ml and is treated with hydrogen at a temperature of 4160 and a pressure of 8 kg / cm 2 before use. The gas oil is through the catalyst bed from top to bottom at a rate of 1040 ml / hour. at a temperature of 4160 and in the presence of enough hydrogen so that the total pressure is 8 kg / cm2. The hydrogen is supplied with the gas oil at a rate of 750 l / l gas oil (measured at normal temperature and pressure). After a running-in period, the gas is made available by recycling some of the gaseous components of the product leaving the reactor. This gas remains mainly hydrogen. The run runs for 50 hours and the results obtained with the various catalysts are shown below. Organic sulfur content CoO MoO3 set (percent by weight) of the liquid product Catalyst manufacturing in Ge in Ge Cataly- after carrier way weight weight sator amount percent percent 10 20 30 40 50 in g (520 ml) Hours hours hours hours hours Aluminum impregnation 2.6 7.5 436 0.50 - 0.57 - 0.63 oxide - 2.2 IO, g 443 0.47 0.5I 0.53 - 0.57 - Co-precipitation 4.9 24.6 438 0.40 0.38 0.46 0.47 0.50 Indian impregnation 1.3 5.4 544 0.53 - 0.56 - 0.61 bauxite - 2.0 8.5 539 0.36 0.38 0.38 0.42 0.43 2.9 14.2 55I 0.50 0.54 o, 56 0.57 o, 58 Example 3 A catalyst prepared according to Example 2 is used for the hydrofining treatment of a Kuwait oil. The test conditions and characteristics can be found in Table I.

In Table 2 is a chemical analysis of both the bauxite catalyst used above as well as a molybdate catalyst on aluminum oxide.

In Table 3 is the sulfur removal by the bauxite catalyst according to the invention with compared to that provided by the alumina catalyst.

From these results it can be seen that for the two catalysts there were no significant differences during the first 30 hours. The alumina supported catalyst is more active than any other in alumina-based catalyst prepared in a similar manner and contains less Cobalt and molybdenum; the advantage of the bauxite-based catalyst is based on that the same activity can be achieved at a lower cost.

Table I. Test conditions: Catalyst charge ........... Volume IOOO ml Weight 1167 g Number of regenerators ..... none Direction of flow ................ downwards Test data: test no.1 test no.2 test no.3 Hours in operation after regeneration 10 25 33 Total operating time of the catalyst in hours 10 25 33 mean bed temperature in ° C .............. 412.0 416.0 414.0 Pressure in the reactor in kg / cm2 ................. 71.0 71.0 71.0 Room flow velocity in V / V / hour I, 02 I, 02 I, 02 Recirculated gas volume in m3 / m3 ................ 709.0 703.0 706.0 Property values of the liquid product: Weight percent of the starting oil ............. 100.0 97.4 98.8 specific weight 15.56 / 15.56 ° .......... 0.8690 0.8510 0.8505 0.8495 Sulfur in percent by weight ................ 2.56 0.19 0.26 0.28 Removed sulfur in% .................... - 92.6 89.8 89.1 Table 2 catalyst Cobalt and Cobalt and Molybdenum oxides Molybdenum oxide on aluminum on bauxite oxide Loss at 550 ° 4.1 9.9 Weight percent of the stable at 550 ° Materials: MoO3 ....... 6.75 23.5 CoO ............. 1.9 4.66 Mesh size (British Standard sieves) 8 to I2 4 to 8 Table 3 Distant Schw; fel in% 10 25 33 Hours hours hours Cobalt and molybdenum oxides on bauxite. 92.6 89.8 89, I. Cobalt and molybdenum oxides on aluminum oxide ............ 92.5 89.0 87.5

Claims (3)

PATENT CLAIMS: I. Process for hydrocatalytic desulfurization of petroleum hydrocarbons at elevated temperatures and pressures in the presence of hydrogen and of catalysts made from a mixture or chemical compound from cobalt and molybdenum oxides or from a mixture of one or both oxides consist of such a compound on a bauxite trihydrate carrier, characterized in that If catalysts are used, their bauxite trihydrate supports at least 2 hours has been heated to 550 ° and thereafter a surface area of more than 120 to 125 qm / g, measured according to the nitrogen adsorption method of B r u n a u e r, E m m e t t and T e l l e r, and which has 1 to 15 percent by weight MoO3 and 0.2 to 3 percent by weight Co 0 included. 2. The method according to claim I, characterized in that the used Catalysts contain 5 to 12 percent by weight MoO3. 3. The method according to claim 1 and 2, characterized in that the The catalysts used contain 2.5 percent by weight of Co 0. Documents considered: British Patent No. 663 o38; U.S. Patent No. 2,194,280; French patent specification No. 864 874.