DE2726126A1 - METHOD OF MANUFACTURING SHAPED ALUMINUM CATALYST MATERIAL - Google Patents

Description

PFENNING MAAS MEINIQ - LEMKE - Mockery SCHLEISSHEIMERSTR.

0000 MUNICH 40

26th

American Cyanamid Company, Wayne, New Jersey, V. St. A. Process for making shaped alumina catalyst

gate material

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The invention relates to the production of catalysts which are used for the hydrotreatment of petroleum fractions ver let it turn. It is primarily aimed at the manufacture of improved catalysts, the oxides of nickel, Contains cobalt and molybdenum. In particular, the invention is concerned with catalysts for hydrosulfurization, denitrification and saturation of aromatics based on an alumina carrier which is of a rehydratable form made of alumina.

Methods of hydrotreating petroleum for desulfurization, nitrogen removal and saturation of aromatics are used by widely used in the petroleum refining industry to improve the petroleum material. Catalysts, used in such hydrotreatments usually contain promoters such as oxides of Cobalt, nickel, molybdenum and tungsten. These catalysts are carried on a base material with a high surface area, such as activated alumina.

The technology already makes use of a wide variety of hydrotreatment catalysts in which an activating metal or metal oxide is carried by or impregnated into an aluminum oxide base material. Alumina of suitable structure and physical properties can be prepared by a number of known methods. Such a catalyst base material can be produced, for example, by hydrolyzing an aluminum alcoholate. The aluminum alcoholate required for this can be formed by reacting aluminum metal with a high-boiling, partially miscible alcohol, such as amyl alcohol, using mercury chloride as a catalyst. The aluminum alcoholate obtained is then hydrolyzed to an aluminum hydroxide, from which aluminum oxide is formed to remove water

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high surface area. Suitable aluminum oxides can also be produced from bauxite concentrate, by dissolving separate quantities of bauxite concentrate in acidic or caustic solutions and the resulting the two solutions then mixed to form clumps of precipitated alumina. By filtering, Washing and spray drying of these tufts give microspheres of precipitated aluminum oxide powder. Then can you moisten this powder again and bring it into the desired shape.

Alumina base materials following those mentioned above or prepared by other methods have proven to be suitable supports for hydrotreating catalysts proven and are commercially available. The physical and chemical properties of active aluminas are however, it is highly dependent on the processes used to produce them. The technique of making active Alumina is therefore highly sophisticated and there are a number of different manufacturing methods that can be optimized certain properties of active alumina so as to meet the needs of the particular specific uses meet. However, the steadily increasing raw material costs also make methods desirable which not only result in an improvement in the product properties, but also keep production costs to a minimum.

The object of the invention is therefore to create a process for the production of hydrotreatment catalysts, which is associated with a cost saving, enables easier manufacture of such catalysts and a catalyst product with good effectiveness, in which one needs only a minimum of activating metal.

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This object is achieved according to the invention by a process for the production of aluminum oxide supports for hydrotreatment catalysts, which consists in first subjecting hydrated aluminum oxide, as is generally obtained from bauxite ore by the so-called Bayer process, to a flash calcination, whereby a partially dehydrated rehydratable product is obtained which consists of anhydrous alumina, lower hydrate forms of alumina, alumina monohydrate and unreacted alumina trihydrate. The rehydratable alumina that can be used in the present process can vary in composition. The powder can usually be characterized by its weight loss on burning (LOI value) and its rehydration index (RI value). The LOI value is determined by measuring weight loss those which 2 hours by heating the alumina powder obtained to 982 ⁰ C. The RI value, which indicates the amount of rehydratable alumina present in the powder, is calculated using the following equation:

_T _ (LOI after rehydration - LOI before rehydration) o _7nn ^Ri ~ 15 (1OO - LOI after rehydration)

The process for making the rehydratable alumina is generally that alumina trihydrate is partially dehydrated by it during a For a fraction of a second to several seconds, it passes through a gas flow at high temperature. The composition of the thereby obtained product varies depending on the alumina trihydrate used as the starting material, its Particle size, the gas temperature and the residence time of the particles in the gas stream. The rehydratable material obtained in this way Powder can then be processed or ground to a smaller particle size, then mixed with water and finally process them into pearls, cookies or extrudates. The alumina formed in this way can then be used to increase

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hardened to its crush resistance. Such hardening is preferably carried out by treatment with steam. The aluminum oxide forms obtained in this way are then dried and calcined. The calcination is normally carried out at temperatures from 427 to 704 ^° C.

The alumina catalyst base material obtained in the above manner is then subjected to a pore impregnation process to thereby incorporate the catalytic promoters. The hydrodesulfurization catalyst (HDS) catalytic promoters are generally selected from oxides and sulfides of metals in Groups VIII or VI of the Periodic Table of the Elements and are usually CoO, NiO or MoO.,. The preferred percentages by weight of these promoters on the catalysts are in the following range: CoO and / or NiO (2-6%) and MoO ₃ (6-24%). Small amounts of other materials can also be present, such as (0-3%) phosphorus and / or silicon dioxide. A preferred method of carrying out the above impregnation is to first determine the pore volume of the alumina molds and then treat this material with an amount of a solution of appropriate soluble salts thereof just sufficient to fill the pore volume of the alumina to introduce the active metals.

A variety of can be used to form shaped alumina bodies known methods can be used, such as beading processes or extrusion processes. Extrudates appear to be preferred in a number of cases Form to be for HDS catalyst support. However, the manufacture of extrudates is unfortunately made up for by the fact makes it difficult, as working with rehydratable aluminum oxide masses showed, such aluminum oxide powders often difficult to shape into extrudates using known extrusion techniques. The manufacture of alumina

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extrudates from rehydratable aluminum oxide masses is therefore not as easy as making it from precipitated alumina. Precipitated aluminum oxide can simply pass through Mix with water and extrude into extrudates. This method fails with rehydratable alumina masses because of the rehydration reaction between the alumina and the water often resulting in a rehydrated cementitious This creates a mass that blocks the extruder screw in the cylinder and prevents extrusion.

One produced by the so-called Bayer process, in which aluminum hydrate is precipitated from sodium aluminate solutions Aluminum oxide inevitably contains sodium compounds as impurities. So if you work with rehydratable Aluminum oxide, then there is another due to the high sodium oxide (Na-O) content of about 0.2 to 0.5% that is present Problem. This amount of sodium oxide has a disadvantageous effect in the case of HDS catalysts. To the sodium content of such To degrade materials, therefore, at some point in the above manufacturing process, there must be a washout or process Removing sodium compounds are incorporated.

In the present case, therefore, a production method has been developed with which the above-mentioned problems can be compensated. As demonstrated here, the alumina can be stabilized when rehydrating the rehydratable alumina powder prior to extrusion so that it is mulling without forming a cementitious mass, and can be extruded. Rehydration can be performed using several alternative methods. The rehydratable alumina can, for example acidic rehydrate by heating the alumina powder in water at about 100 ⁰ C for several hours with about 4 to 5% nitric acid, based on the weight of the alumina. You can then use this slurry

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filter, wash and spray dry before rolling and extruding them. There is another and more appropriate procedure for this in an acid rehydration of the alumina under a high concentration of solids, so that the resultant Mixture can then tumble and extrude directly.

Acid rehydration is likely to result in partial rehydration of the rehydratable aluminum oxide with the formation of a stable monohydrate form which is not rehydrated further under the conditions of mulling and extrusion. The use of nitric acid for this purpose has proven successful, but other acids can easily be used instead, such as H ₃ PO ₄ , H-SO- or H ₃ CO ₃ . Corresponding investigations have led to the fact that the above-described rehydration stage should preferably be carried out at a pH value of below 7, since here in particular the formation of the desired monohydrate occurs, whereby a product with a high surface area and micropores is formed, so that one finally a catalyst with higher HDS activity is obtained. A rehydration at a pH value above 7 leads to the formation of a mixture of mono- and trihydrates, and thus not predominantly of monohydrate.

It has been found to be particularly advantageous with the present one Method of rehydration to use carbonic acid. To this end, the aqueous slurry of rehydratable material is added Aluminum oxide together with carbon dioxide, which lowers the pH value. The relatively weak carbonic acid is sufficient to prevent trihydrate formation during rehydration suppress and remove sodium impurities. During the high temperature calcination in the manufacture of the catalyst the resulting carbonate residues are released into the atmosphere, thereby eliminating the problems of air pollution are minimal.

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Another variation on the rehydration process is based on the observation that slurries of rehydratable Alumina readily forms a high solids filter cake (about 50 to 55%) at ambient temperature let filter. Rehydratable aluminum oxide can therefore be slurried at ambient temperature (solids content preferably about 10 to 20%) and then neutralize with acid, filter and wash. In this way the sodium content can be reduced decrease to less than 0.03%. The filter cake obtained is then used to rehydrate the aluminum oxide heated, whereupon the resulting material is rolled and extruded.

The above-described rehydration process using a high solids material thus consists in heating a high solids slurry, and during this process the slurry changes from a liquid to a solid cake. The received Cake must therefore be crushed before being rolled. This additional measure can be avoided by using rehydration carries out in a heated mixer, whereby a granulate-like product is obtained, which directly tumble or can extrude.

A modification of the above process is that a slurry of rehydratable alumina (solids content preferably about 20%) is treated with carbon dioxide with the application of heat and pressure, resulting in a slurry which results directly in a high solids, low content filter cake can be filtered on Na ₂ O, which can then be rolled or extruded directly. This process is preferably carried out at a temperature of about

2 65 ⁰ C and a pressure of about 7 kg / cm. '

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After the molded alumina support has been prepared as described above, the catalysts are formed by impregnating the alumina support with solutions of the active metals. The pore volume of the aluminum oxide bodies can be determined by titration. Corresponding soluble salts of cobalt (and / or nickel), molybdenum (and / or tungsten) and phosphorus are dissolved in so much water that an amount of solution just sufficient to fill the aluminum oxide pores is obtained. The solution obtained in this way and the aluminum oxide bodies are then mixed with one another and are preferably kept in this state for about 0 to 4 hours, after which they are dried and calcined. The Co (Ni) and Mo (W) salt solutions can be impregnated into the alumina by separate steps or, alternatively, a solution can be prepared which contains two or more salts when working with a suitable stabilizer. Examples of such stabilizers are H ₃ PO ₄ , NH ₃ or various polybasic organic acids, such as citric acid or tartaric acid.

The invention is further illustrated by the following examples.

Production of an extrudate from rehydratable aluminum oxide example 1

400 g of a rehydratable aluminum oxide powder (RI value = 50) are added over a period of 5 minutes to an ^{acidic solution, heated to 85 °} C., of 20 g of nitric acid in 3 l of water. The temperature of this aluminum oxide-acid mixture is then kept at 90 to 100 ^° C. for 2 hours. At the end of this time, the reaction mixture has a pH of 5.3. Subsequent addition of 18 ml of 29 percent ammonia increases the pH of the mixture to 7.3. The aluminum oxide is then filtered off and washed. The material obtained is then slurried again and spray-dried, whereupon

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the powder produced in this way is rolled for 30 minutes with 120 g of water and 2 g of NH3 and then extruded. The extrudates obtained are dried calcined first 3O minutes at 121 ⁰ C and then for 1 hour at 649 ⁰ C. Examination of the product made in this way shows that it has a pore volume of 0.68 ml per g.

Example 2

600 g of a rehydratable aluminum oxide powder (RI value = 50), 500 g of water and 25 g of HNO _{3 are} mixed together to form a slurry. The slurry was then heated in a closed vessel for 1 hour at 80 to 9O ⁰ C. Subsequently Kollert to the cured mixture obtained 30 minutes by 35 ml of 29-percent NH _3. The Koller mixture is extruded thereon, and the thus obtained molded extrudates are then dried and then calcined first at 649 ⁰ C at 121 ⁰ C. The calcined extrudates are washed then about 1 hour by 10 to 20 times its weight of water, and they are calcined and dried at 538 ⁰ C. The product produced in this way has a pore volume of 0.69 ml / g.

Example 3

600 g of a rehydratable aluminum oxide powder (RI value 51) are mixed with 490 g of water at room temperature. The pH of the slurry is then lowered from about 9 to about 7 by adding nitric acid (about 1 percent by weight of the aluminum oxide). The slurry is then filtered and the filter cake is washed. The filter cake contains 50 to 55% Al ₃ O ₃ . For rehydration, this filter cake is then heated in a closed container for about 1 hour

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(Temperature 80 to 90 ⁰ C), after which the material thus obtained Kollert and extruded. The extrudates obtained here are dried and calcined as described above. They have a pore volume of 0.78 ml per g.

Production of an HDS catalyst Example 4

The process described in Example 1 is used to produce an extrudate from rehydratable aluminum oxide which has a pore volume of 0.68 ml per g. According to a determination, 89 g of a sample of this extrudate have a total pore volume of 60.6 ml. A catalyst metal solution is then prepared which contains 16.8 g of Co nitrate (2.5 g of CoO) and 1.9 g of 85 percent strength Contains H ₃ PO ₄ (0.5 g P). This solution is then mixed with 8.0 g of MoO-, which is dissolved in an equimolar amount of NH ₃ , up to a volume of 32 ml. The solution is then diluted to a total volume of 60.6 ml (which is the total pore volume corresponds to the aluminum oxide extrudates). The formed alumina and the above metal solution are then mixed together and left in a closed container for 30 minutes. The extrudates impregnated in this way are then ^{dried at 121 °} C. for 30 minutes and then calcined ^{at 538 °} C. for 1 hour. A corresponding analysis of the finished catalyst obtained in this way shows the following composition: 89 percent by weight Al ₃ O ₃ , 2.5 percent by weight CoO, 8 percent by weight MoO ₃ and 0.5 percent by weight P.

Example 5

An extrudate is produced from rehydratable aluminum oxide which has a pore volume of 0.76 ml per g. Following that a catalyst metal solution is prepared containing 37.3 g

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Contains cobalt nitrate solution (4.0 g CoO) mixed with 3.0 g of 85 percent H ₃ PO ₄ (0.8 g P). This solution is mixed with 12 g of MoO ,, which is dissolved in an equimolar amount of NH, (4.8 ml of 29 percent NH,) to a total volume of 36 ml Diluted total volume of 65 ml, whereupon they are mixed with 83.2 g of the above aluminum oxide extrudates (total pore volume 65 ml). The mixture is left to stand for 45 minutes, after which it is first dried at 121 ^° C. for 1 hour and then calcined at 538 ^{° C. for 1 hour.} The finished catalyst obtained in this way is composed as follows: 4 percent by weight CoO, 12 percent by weight MoO, 0.8 percent by weight P and 83.2 percent by weight Al ₃ O ₃ .

Example 6

The process described in Example 3 is used to produce an extrudate from rehydratable aluminum oxide which has a pore volume of 0.78 ml per g. 84 g of a sample of this extrudate are weighed out, and this amount of sample has a pore volume of 65.5 ml. To prepare a catalyst metal solution, 12.0 g of MoO ₃ are then dissolved in 4.8 ml of 29 percent NH, up to a volume of 48 ml. This solution is then diluted to 65.5 ml and mixed with the aluminum oxide extrudate. The mixture is left standing, and then calcining the extrudates first at 121 ⁰ C and then dried at 538 ⁰ C for 30 minutes. A second catalyst metal solution is then prepared by diluting 37.3 g of a cobalt nitrate solution (4.0 g CoO) to a volume of 60 ml and then mixing this solution with the aluminum oxide extrudates impregnated with molybdenum. The whole thing is left to stand for 30 minutes, after which the extrudates are first ^{dried at 121 °} C. and then at

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538 ⁰ C calcined. The finished catalyst obtained in this way has the following composition: 4 percent by weight CoO, 12 percent by weight MoO, and the remainder Al ₃ O ₃ .

Example 7

Corresponding beads with a pore volume of 0.80 ml per g are produced from a rehydratable aluminum oxide. 83.25 g of these beads are weighed out, and the total pore volume of this sample is 66.6 ml. A catalyst metal solution is then prepared _{which contains 12.0 g of MoO 3 , 1.98 g of CoCO 3} and 2.37 g of H ₃ PO ₄ contains. This mixture whereupon it is treated until clear the solution for 3 hours at 90 to 100 ⁰ C is treated with 50 ml of water. The solution is then cooled to room temperature, whereupon 13.5 g of cobalt nitrate solution (14.9 percent by weight CoO) are added. The solution thus obtained is then diluted to 66.6 ml (this volume corresponds to the total pore volume of the aluminum oxide beads). Then mixed to the alumina beads and the catalyst solution with each other and leaves the whole 30 minutes in a closed container, followed by drying the material thus obtained first for 30 minutes at 121 ⁰ C and then calcined for 1 hour at 538 ⁰ C. The finished catalyst produced in this way has the following composition: 4 percent by weight CoO, 12 percent by weight MoO ₃ , 0.75 percent by weight P and the remainder Al _? 0 ,.

Catalyst activity

The catalytic effectiveness of the HDS catalysts, which by Solution impregnation of aluminum oxide carriers, which are formed from rehydratable aluminum oxide masses, is quite cheap compared to commercial HDS catalysts.

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The determination of the corresponding HDS activity is carried out using what is known as a batch agitation test reactor (BST reactor). For this experiment, a certain amount (10 g) of a presulphided catalyst (the mixture of cobalt and molybdenum oxides is converted _{into the corresponding sulphides by heating in a mixture of H 2} and H ₂ S) and a certain amount (300 g) oil in a high pressure reaction chamber. The reaction chamber is then closed and then pressurized with hydrogen to an appropriate pressure (227 kg - 500 lbs.). ^{The reaction vessel is then heated to the working temperature (320 °} C.) while continuously passing hydrogen through the oil at a rapid rate (2 liters per minute). Oil samples are taken at intervals of 0.5 hours and analyzed for their sulfur content. The analysis of this sulfur as a function of time gives a rate constant which is a measure of the rate of the hydrodesulfurization reaction (for the particular catalyst and the oil used in each case under the specific conditions of temperature, pressure and the like).

In a similar experiment, so-called catalysts are used to determine the catalytic effectiveness of the HDS catalysts Drip bed reactors. These reactors have the advantage that the way they are operated resembles an actual refinery unit comes closer. To do this, a fixed bed column of the catalyst is used and the oil is left at a certain flow rate drip or trickle through this column. At the same time as the oil is carried out, the flow rate is constant and constant pressure also include hydrogen. After reaching a state of equilibrium, you analyze it leaking oil on its sulfur content. This sulfur analysis can be combined with the flow velocity for relate the oil and the like to a rate constant for the HDS reaction.

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In each of the above HDS experiments an absolute measure is obtained for the rate of reaction (the rate constant). However, this speed is dependent on the experimental conditions (temperature, pressure, flow rate and the like) under which it is determined. It A conversion into a relative reaction rate or a relative activity is therefore recommended. One of those Value simply corresponds to the ratio of the rate constant for the respective catalyst and the (among the same conditions) certain rate constants for a certain standard catalyst. This ratio, and thus the relative activity does not change significantly with the test conditions, although the individual rate constants can of course be very different from each other. As a standard for comparing the activity of other catalysts the catalyst HDS-2A is used here. This catalyst is a recognized one commercial HDS catalyst from American Cyanamid Company. By comparing the effectiveness of equal amounts of catalyst by weight one obtains the so-called relative weight activity (RWA value), and a comparison with the effectiveness of the same The volume of the catalyst gives the so-called relative volume activity (RVA value). The RVA value can be derived from the RWA value simply calculate by comparing the latter with the ratio of the density of the catalyst (compressed bulk weight or so-called CBD value) and the density of the standard divided. The extrudates examined here have a diameter of approximately 0.165 to 0.177 cm and lengths of about 0.254 to 1.27 cm. The catalyst beads examined have a diameter of about 0.168 up to 0.239 cm. The so-called LOI values and RI values for the Powder of rehydratable alumina from which the beads or extrudates used herein are made are shown in Table I below. This table also contains the relevant examinations Solution-impregnated, rehydratable HDS catalysts based on aluminum oxide obtained comparable catalytic Activities indicated.

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Tabel

Aluminum oxide base material (made from rehydratable aluminum oxide)

Standard HDS-2A

Composition of
Catalyst metals RWA RVA CoO / Mo0 ₃ / P

3/15 100 100

Pearl LOI = 6.8 RI = 56

Pearl LOI = 7.3 RI = 50

Extrudates from the HNO ₃ rehydration process of Example 1

RI value = 50 LOI value = 6.6

Extrudates from the HNO ₃ rehydration process of Example 2

RI value = 51 LOI value = 7.2

2.5 / 8 / 0.5 116 151 4/12 / 0.75 97 130 5/16/1 95 132 2.5 / 8 / 0.5 95 124 4/12 / C, 75 96 129 2.5 / 8 / 0.5 116 137 2.5 / 8 / 0.5 114 147 2.5 / 8 / 0.5 112 148 3/9 / 0.6 112 152 4/12 / 0.8 116 151 2.5 / 8 / 0.5 114 135 4/8 / 0.8 110 130 4/12 / 0.8 105 131 4/8 112 130 4/12 101 119

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Table I (continued)

Aluminum oxide base material (made from rehydratable aluminum oxide)

RI value = 56 LOI value = 6.8

Composition of
Catalyst metals
CoO / MoO-j / P

RWA RVA

Pearl LOI value = 9.0 2.5 / 8 / 0.5 86 103 RI value = 49 Pearl LOI value = 6.8 2.5 / 8 / 0.5 102 129 RI value = 56 4/12 / 0.75 93 120 5/16/1 99 140 Extrudate from the
HN0 ₃ ~ rehydration 2.5 / 8 / 0.5 1O5
110 127
133

Pearl LOI = 7.3 RI = 50

Pearl LOI = 6.6 RI = 50

2.5 / 8 / 0.5 98 95 4/12 / 0.75 87 90 2.5 / 8 / 0.5 1OO 88 2.5 / 8 / 0.5 93 86

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Claims (11)

Godfather ta η s ρ rü che Method of making shaped alumina catalyst material, characterized in that one first comprises a mass of an active alumina which contains a rehydratable form of aluminum oxide, then this mass of aluminum oxide for stabilization rehydrated the rehydratable form of aluminum oxide, the resulting mass of rehydrated aluminum oxide mixed with water to form an aqueous paste, the paste thus formed of aluminum oxide by extrusion into brings the desired shape and the formed aluminum oxide obtained is finally calcined by heat treatment. 2. The method according to claim 1, characterized that the sodium compounds (sodium oxide) present as an impurity are removed from the aluminum oxide washes out at a certain stage of the process. 3. The method according to claim 2, characterized in that the rehydration is based on an aqueous slurry at a pH below 7. 4. The method according to claim 3, characterized that the pH is kept below 7 by adding acid. 5. The method according to claim 4, characterized in that the acid used is nitric acid, Sulfuric acid, phosphoric acid and / or carbonic acid used, 709851/1073 ORIGINAL INSPECTED 6. The method according to claim 5, characterized that the pH of the aqueous slurry by introducing carbon dioxide to below holds. 7. The method according to claim 5, characterized in that the pH of the aqueous slurry by adding nitric acid to below 7
holds. 8. The method according to claim 2, characterized in that the rehydratable mass of aluminum oxide is mixed with water to form an aqueous slurry, this slurry is then added to maintain a pH below 7 with acid, the aqueous slurry of aluminum oxide thus obtained
then filtered to form a filter cake with a high solids content, the resulting filter cake was then washed with water to remove sodium impurities (sodium oxide) and the washed filter cake thus obtained was finally heated to rehydrate the rehydratable aluminum oxide. 9. The method according to claim 2, characterized that the obtained aluminum oxide moldings for hardening a certain hardening stage undergoes. 10. The method according to claim 9, characterized in that the hardening stage in one Treatment process with steam consists. 709851/1073 11. The method according to claim 1, characterized that the activated aluminum oxide moldings obtained thereafter with a catalytic Impregnated promoter solution and the thus impregnated aluminum oxide activated by a calcining heat treatment. 709851/1073