DE1078097B - Process for the improvement of catalyst carriers made of aluminum oxide - Google Patents

Description

It is known that the structure of catalyst supports, in particular from active aluminum oxide, an influence on the activity and selectivity of the Owns catalyst. Catalysts that usually use aluminum oxide as a carrier, are z. B. Various types of reforming catalysts. These include, on the one hand, those contain the elements of group VIII of the Periodic Table, generally platinum or palladium, often combined with halogens, such as chlorine or fluorine, on the other hand the catalysts, the oxides or Contain sulphides of molybdenum, tungsten or vanadium.

A well known reforming catalyst contains 0.1 to 1.0%> Platinum and 0.1 to 8% halogen on an active alumina support. The halogen is usually chlorine and / or fluorine.

Other catalysts with active alumina as a carrier are hydrogenation and / or desulfurization catalysts, in which, for example, molybdenum and cobalt or molybdenum and nickel are used instead of platinum.

The aim of the present invention is the production of activated alumina, which when used These catalysts are excellent supports, for example, for reforming catalysts Makes it effective even with low platinum contents. The active alumina treated according to the invention also provides a considerably improved catalyst support for reforming, hydrogenation or desulfurization catalysts.

Any type of aluminum oxide of the required purity can be used for the process according to the invention Find raw material use.

While not essential to the invention, it is preferred that an active alumina be used assume that has been formed into the shape desired for the final catalyst particles and for example as tablets, extrusions, beads or in any other form.

This in the usual way initially at a temperature of about 450 to 850 ° C, preferably from about 650 to 800 ° C, activated alumina is treated with an acid such as nitric acid and / or dilute hydrochloric acid. According to the invention, at least approximately 1% to a maximum of about 20% of the active alumina can be dissolved. Such an extraction significantly improves the properties of the final catalyst. One possible explanation for this improvement may be seen in the fact that due to the extraction of most of the from Dissolved alumina inside the alumina particles makes the final catalyst easier to process For improvement

of catalyst carriers

made of aluminum oxide

Applicant:

Koninklijke Zwavelzuurfabrieken
ι »v / h Ketjen NV,

Amsterdam, Netherlands)

Representative: Dr. F. Zumstein,
Dipl.-Chem. Dr. rer. nat. E. Assmann

and Dipl.-Chem. Dr. R. Koenigsberger, patent attorneys, Munich 2, Bräuhausstr. 4th

Claimed priority:
Netherlands February 1, 1958

Johan Pieter Abrahams, Amsterdam (Netherlands),
has been named as the inventor

becomes accessible to the molecules of the material to be treated. A process in which aluminum oxide-containing support material activated by heating is treated with hydrochloric acid is known per se, but in this known process no extraction is carried out, instead the acid-treated catalyst support is immediately dried and heated, whereby sublimable AlH _{3 is} expelled.

In accordance with the invention, less than about 3% of the alumina can be extracted. It will

4Q preferred to continue the extraction, since such minor extractions do not provide all of the achievable benefits. Stronger Extractions of more than about 20% are generally unfavorable because they result in a particularly large drop is effected in the mechanical properties of the alumina particles. Treatment with hydrochloric acid is preferably done so that about 3 to 15% of the aluminum oxide is dissolved. A suitable embodiment is treating the active alumina with 0.5 to 5 η-hydrochloric acid. The amount of hydrochloric acid should be sufficient to achieve the desired amount of aluminum oxide in Aluminum trichloride convert to the surface of the active aluminum oxide with chloride ions

909 757/393

to saturate and also to ensure a small excess, for example of about 50%.

When the active alumina is treated with the acid, the temperature rises depending on the nature the aluminum oxide used and the concentration of the acid to a certain extent. For practical reasons it is undesirable for the temperature to rise above 80 ° C., although above good results can be achieved at this temperature. If the temperature rises above 50 ° C, the Maintained temperature above 50 ° C until the desired conversion has occurred to about 95%.

If low concentrations of acid are used, the temperature will be after contacting of the alumina with the acid below 50 ° C. The mixture is then brought to about 50 ° C heated and held at that temperature until about 95% of the reaction is complete. in the generally this is the case within 1 hour.

A temperature of approximately 50 ° C. has proven to be favorable for carrying out the extraction. However, this temperature is by no means essential for obtaining excellent results. Below around 50 ° C, however, the reaction proceeds relatively slowly, and unnecessarily fast at higher temperatures themselves.

The approximately 50% excess acid is also chosen for practical reasons only. the The rate of reaction is such that a 95% conversion is achieved in a reasonable time. Considerable additional time is required to complete the reaction even further.

When the reaction is complete, the aluminum oxide is washed thoroughly with water to eliminate the excess acid and the dissolved aluminum salt washed.

The process according to the invention for producing the catalyst supports also contains a calcination stage of the acid-leached, active aluminum oxide at 500 to 850 ° C. In a preferred In the embodiment, the acid-treated aluminum oxide is calcined at 650 to 800 ° C. While the calcination results in a favorable change in the porosity of the aluminum oxide. The number of Pores below about 70 Å in diameter are considerably reduced throughout Pore volume remains essentially the same. This, in principle, known elimination of the larger part the small pores has a particularly beneficial effect on the properties of the final catalyst.

The observed change in the porosity of the active alumina may be the joint effect can be attributed to acid treatment and subsequent calcination. Also an extended one Calcination of the original alumina, even at temperatures of around 850 ° C, however, it is not sufficient to achieve this same effect. Although an increase in the average pore diameter is observed, the elimination is the pores with a diameter below about 70 Å are much smaller than when the aluminum oxide is subjected to treatment with acid. According to the invention, the calcination temperature and duration of the acid-treated aluminum oxide can be varied within relatively wide limits.

Calcination for several hours at about 550 ° C already gives a noticeable reduction the number of small pores. At higher temperatures, for example between 700 and 800 ° C, goes this diminution occurs much more quickly and completely.

In general, calcination is about

30 minutes to a few hours is sufficient. Prolonged heating does not improve the properties of the Aluminum oxide to a noticeable extent and is therefore not necessary or even undesirable.

It is true that at temperatures above 800 ° C, the desired elimination of pores with a lower Diameter than about 70 Å. However, there is an unfavorable change in properties of aluminum oxide (formation of the inactive α-form). At temperatures above approximately 850 ° C these adverse effects outweigh any beneficial changes in properties. Not for everyone Kinds of active alumina are the optimal calcination conditions of the acid-treated alumina same. These favorable conditions can be found for every type of active aluminum oxide however easy to determine.

The expression "pore diameter" is ambiguous, because it requires a certain shape of the pores. There are three main types of catalyst carriers differentiate from pores:

1. The layered between more or less regular Particle lying spaces;

2. the plate-like pores that occur in layered structures;

3. the more or less tubular pores.

Usually two or all three types of pores occur simultaneously in a catalyst support. Of the The term "pore diameter" must therefore be defined on a strongly idealized model.

If the pores are viewed as cylindrical "tubes", a model that is often used, the proportion of pores below a certain diameter in the total pore volume can be calculated from the desorption part of the adsorption-desorption isotherm of nitrogen at the boiling point of liquid nitrogen. These calculations are based on the Kelvin formula. This method, described by EP Barret, LG Joyner and PP Halenda, Journ. of Amer. Chem. Society, 73, p. 373 (1951) has been used here. The pore volume is derived from the nitrogen adsorption at p / p ₀ = 0.98. This means that the pore volume present in the pores up to a diameter of approximately 500 Å is measured.

Reforming catalysts containing elements of Group VIII, which are composed of a certain type of Alumina have been produced, show a much lower activity than comparable ones from The same type of aluminum oxide produced catalysts in which the aluminum oxide according to the invention was treated. The same applies to any other catalyst produced with the aid of the invention Carrier was prepared.

The process of making the active alumina catalyst supports is not essential for the present invention. Any known method can be used for this purpose. Also are for the invention the nature and amount of catalytic metals or the use of accelerators, like halogens, not essential. In reforming catalysts, platinum is often used in amounts of about 0.1 to 1.0%> used. In this case, the alumina treated according to the invention can be used impregnated with a solution of platinum hydrochloric acid by any known method

the. Additional treatments with hydrogen or ammonium sulfide can also be used. The following examples illustrate the invention.

example 1

Three different types of active alumina A, B and C, all in the shape of cylindrical ones Tablets with a diameter and height of 3 mm were subjected to the following treatment:

250 g of active aluminum oxide were added to 375 g of 16% hydrochloric acid in a beaker. The temperature of the mixture rose by a certain amount depending on the type of aluminum oxide used. After a treatment time of 20 minutes, the aluminum oxide tablets were washed first with cold, distilled water and then with distilled water at 50 ° C. by decanting until the discharge gave only a weak reaction to chloride ions. The tablets were dried at 120 ° C and then calcined 2 ¹ Za hours at 750 ° C.

The temperature rise during the treatment of oxides A, B and C with hydrochloric acid was 65.25 and 56 ° C. The percentages of aluminum oxide extracted from the tablets were 12.7, 10.8 and 10.6%, respectively.

The products obtained from oxides A, B and C were designated Al, B 1 and Cl. Some essential physical properties are in the listed in the following table.

Al aluminum oxide
BI Bl

Cl

Effective surface (m ² / g)

Pore volume (cm ³ / g)

Distribution of pore size (percentage of the pore volume that is in pores with a diameter smaller than the specified)

<70 Ä

<80Ä

<90Ä

<100Ä

<110Ä

222 0.40

30 51 72 88 95

191 0.45

As a result of the treatment, the effective surface areas of the aluminum oxides had decreased, while the pore volumes had become somewhat larger. The proportion of pores with a diameter below about 70 Å in total pore volume had decreased considerably. Both the original Alumina like the treated alumina have been used in the manufacture of reforming catalysts used.

To do this, the aluminum oxides were mixed with a solution of platinum hydrochloric acid and hydrochloric acid impregnated, then dried and annealed at a temperature of 540 ° C.

The obtained catalysts were compared in their effectiveness for reforming hydrocarbon mixtures in the following manner :

45 ml of the catalyst were in a reaction vessel at 492 ° C under a hydrogen pressure of 13.5 atmospheres heated. A mixture of a paraffin oil with a boiling range was used for 20 hours from 100 to 160 ° C and hydrogen in a molar ratio of 1: 5 passed through the reaction vessel. The pressure was at 13.5 atmospheres, the temperature at the inlet end of the catalyst bed held at 492 ° C. The flow rate was kept constant during the experiment. From the received The aniline point was determined for reformed oil.

The rate at which this aniline point was obtained was compared to the rate at which a standard reforming catalyst was obtained produces a reforming oil with the same aniline point. The other conditions of the experiment were identical.

The ratio of the flow rate of the catalyst under test to that of the standard catalyst, expressed as a percentage, was found to be 242
0.33

65
68
70
72

74

155
0.36

20th
33
45
56
65

253 0.47

27 39 55 82 87

197 0.49

14 22 32 43 53

Volume activity of the catalyst to be tested denotes.

The results of the reforming attempts were as follows:

sample Bulk density
of the pre-compression
teten material
(g / cm ³ ) Pt
(Weight Cl
percent) volume
activity
(Default
catalyst
= 100) A. 0.80 0.38 0.57 90 Al 0.78 0.38 0.60 165 B. 0.85 0.37 0.51 115 Bl 0.82 0.37 0.60 200 C. 0.69 0.37 0.54 85 Cl 0.66 0.37 0.63 140

Those produced from the aluminum oxides A 1, Bl and Cl Catalysts are much more active than those made from the original aluminum oxides A, B and C. produced catalysts.

Example 2

The aluminum oxides A, B and C were calcined at 780 ° C. for 1 hour. The aluminum oxides obtained were designated as A2, B 2 and C2. These aluminum oxides were then treated with hydrochloric acid treated according to the procedure described in Example 1. The temperature rise during contacting the aluminum oxides with hydrochloric acid were 52, 23 and 39 ° C. The percentages of extracted aluminum oxide were 10.5, 8.5 and 8.9%, respectively. The aluminum oxides obtained were designated A 2-1, B 2-1 and C 2 * 1. The physical properties are shown in the following table.

A2

A 2-1

Aluminum oxide
B2 I B2-1

C 2

C 2-1

Effective surface (m ² / g) ..

Pore volume (cm ³ / g)

Distribution of the pore size (° / ο)

<70Ä

<80Ä

<90Ä

<100Ä

<110Ä

194
0.38

23
37
56
74
83

168
0.455

7th
12th
20th
29
40

177
.0.32

49
58
64
68
70

140
0.355

15th
28
41
51
61

202
0.44

19th
28
42
56
70

185
0.505

10
15th
23
31
38

In this case, too, there will be a decrease in the effective surface area, an increase in the pore volume and a significant decrease in the proportion of pores with a diameter below 70 Å in the total pore volume observed as a result of treatment.

From a comparison with the values of Example 1, the result of the calcination at 780 ° C. is that the effective surface and the pore volume decrease. The pore volume present in pores less than about 70 Å in diameter is reduced much less than a treatment according to the invention.

A comparison of the physical constants of the oxides Al, Bl and Cl with the oxides A2-1, B2-1 and C2-1 shows that in the latter row the eradication of the small pores is more complete, while the pore volumes have remained the same.

The aluminum oxides A 2, B 2 and C 2 and the aluminum oxides A2-1, B 2-1, and C 2-1 were used for production of reforming catalysts in the manner described in Example 1 used.

The activity of the catalysts obtained was compared with that of the standard catalyst. The results are the following:

After washing with water until the drain gave only a slight reaction to chloride ions the samples dried at 120 ° C and then calcined at 750 ° C for 3½ hours. The received Aluminum oxides D1-1, D 2-1, D 3-1 and D 4-1 were prepared according to the procedure described in Example 1 ao wisely converted into reforming catalysts. The activities of these catalysts were with the of the standard catalyst. The results were as follows:

Bulk density Pt Cl 0.52 volume ■ n T_ of the pre-compression 0.54 activity sample teten material (Weight percent) 0.53 - - (g / cm =) 0.38 0.55 115 Dl 0.58 0.39 125 D2 0.59 0.39 130 D3 0.59 0.37 120 D4 0.60

Bulk density Pt Cl 0.55 Volume- of the pre-compression 0.63 activity .Sample teten material (Weight percent) 0.54 (g / cm ») 0.38 0.57 100 A2 0.81 0.39 0.51 170 A2-1 0.78 0.38 0.60 130 B2 0.86 0.39 220 B 2-1 0.82 0.38 95 C2 0.70 0.37 145 C 2-1 0.67

Example 4

The following experiments were carried out with aluminum oxide A 2:

100 g samples of the aluminum oxide tablets were mixed with hydrochloric acid solutions of various concentrations treated. The amount of these solutions was chosen so that the same amount of hydrochloric acid in each experiment was present:

The activities of the catalysts A2-1, B 2-1 and C 2-1 are therefore considerably higher than those of the catalysts A 2, B 2 and C 2.

A comparison with the corresponding catalyst of Example 1 shows that the calcination at 780.degree favorably affects the activity of the final catalysts.

Example 3

Four samples of active alumina D in the form of cylindrical tablets of 3 x 3 mm were obtained Calcined for 1 hour at 500, 650, 780 or 850 ° C. The aluminum oxides obtained were identified as Dl, D 2, D 3 and D denotes 4. The aluminum oxides D1, D 2, D 3 and D 4 were then treated with dilute hydrochloric acid treated.

In each case 250 g aluminum oxide tablets were mixed with 375 ml 5 η hydrochloric acid and Digested at 70 ° C for 20 minutes.

Tablets concentration lot attempt
Mt weight of hydrochloric acid the solution 1ΝΓ. (S) (Normality) (cm*) 1 100 1 500 2 100 2 250 3 100 3 166 4th 100 4th 125 5 100 5 100

The temperature rise during the treatment of the aluminum oxide with the hydrochloric acid solution was 6, 19, 30, 41 or 58 ° C.

The reaction mixtures 1 and 2, in which the temperature was less than 50 ° C, were heated 25 minutes at 5O ⁰ C. The reaction mixtures 3, 4 and 5 were cooled to 50 ° C. in the course of 25 minutes.

All reaction mixtures were then held at 50 ° C for 20 minutes.

The reaction mixtures were then placed in vertical glass tubes placed at the bottom of a drainage pipe were appropriate. In this column the aluminum oxide was replaced by excess hydrochloric acid and aluminum trichloride washed free with distilled water at 50 ° C. The tablets were at 120 ° C dried and then calcined at 750 ° C for 1 hour

The results were as follows: Subs dance name Extraction (%) Attempt no. A 2-2 6.3 1 A 2-3 8.1 2 A 2-4 8.2 3 A2-5 8.3 4th A 2-6 8.4 5

The percentage of alumina extracted over a period of time increased with increasing hydrochloric acid concentration. This increase was normal at concentrations above about 2 but only relatively small. To get better results with hydrochloric acid concentrations of Normal or To achieve less, longer reaction times or higher temperatures are required.

The aluminum oxides A 2-2 etc. became reforming catalysts prepared in the manner described in Example 1. The activities of these catalysts were with the standard catalyst compared. The results were as follows:

Bulk density Pt Cl 0.50 volume of the pre-compaction 0.49 activity Jrrobe teten material (Weight percent) 0.47 (g / cm ³ ) 0.39 0.47 140 A 2-2 0.79 0.38 0.45 145 A 2-3 0.78 0.38 145 A 2-4 0.78 0.37 145 A 2-5 0.78 0.38 145 A 2-6 0.77

10

Example 5

The following experiments were carried out with aluminum oxide A 2:

200 g samples of alumina tablets were combined with hydrochloric acid solutions, the concentrations between about normal and 2normal.

The volume of the solutions was varied only slightly, so that the samples with different amounts Hydrochloric acid.

Tablet concentration lot No. weight of hydrochloric acid the solution (G) (Normality) K) 1 200 1.07 750 2 200 1.25 800 3 200 1.50 800 4th 200 1.80 850 5 200 2.00 1000

When the tablets were treated with the acid, the temperature was below in all experiments Maintained 50 ° C. Within 25 minutes the temperature rose to 50 ° C. and was at this temperature Held for 20 minutes.

The tablets were then washed, dried and calcined as described in Example 3. The aluminum oxides were then converted into reforming catalysts in accordance with the procedure described in Example 1 manufactured. The results were as follows:

substance extraction Bulk density Pt Cl -
0.52 volume attempt description (° / o) of the pre-compaction (Weight percent) 0.53 activity No. A 2-7 3.8 teten material
(g / cm ³ ) 0.36 0.51 135 1 A2-8 7.4 0.80 0.37 0.52 145 2 A 2-9 8.6 0.78 0.37 0.51 145 3 A2-10 10.4 0.76 0.37 145 4th A 2-11 16.8 0.75 0.38 145 5 0.71

It can be seen from the values that the percentage of aluminum oxide extracted from the tablets increases, if more hydrochloric acid is used based on the amount of tablets.

The volume activity increases up to about 7% extracted alumina and then remains constant.

The bulk density of the catalyst decreases steadily with increasing extraction. It means that for example the same volume activity with sample A1-11 is obtained as with sample A 2-8 with a somewhat low platinum weight in the reaction vessel.

A comparison of the catalyst A 2 (Example 2) shows that the process according to the invention is too leads to a much improved catalyst, even if the extraction levels are only 3.8%. 6g

Example 6

The following experiments were carried out with the active aluminum oxide A 2:

400 g aluminum oxide tablets were made with 2 1 1.34 N hydrochloric acid extracted, washed and dried, as described in example 4.

The product was divided into four equal parts and stored for 3 hours at 540, 660, 730, 780 and 840 ° C, respectively calcined. The obtained aluminas were processed with platinum and the activities of the obtained Catalysts compared with that of the standard catalyst.

The results were as follows:

Calcic Schütt Pt Cl 0.54 volume renational density of 0.59 activity P _m La tempe- predicted 0.58 1 ΓΟ Dc rature wrote (Weight percent) 0.54 Materials 0.56 135 540 (g / cm ³ ) 0.38 145 A2-12 660 0.80 0.38 150 A 2-13 730 0.80 0.38 155 A2-14 780 0.80 0.37 125 A2-15 840 0.81 0.38 A2-16 0.81

909 7-67 / 393

sample

Bulk density

of the pre-compression

teten material

(g / cm »)

0.75

0.73

Pt

Cl

(Weight percent)

0.39
0.38

0.45
0.49

Volume activity

100
170

The activity increases with increasing calcination temperature until a maximum is reached. then the activity drops off very quickly.

Example 7

100 g of an active aluminum oxide E in the form of irregular grains with a size between 1.2 and 2.0 mm were treated with 0.51 η-hydrochloric acid in the manner described in Example 4. To Washing and drying, the product was calcined at 750 ° C. The obtained alumina was as El designated.

The aluminum oxides E and E1 were platinum processed and the reforming catalysts obtained in terms of their activity with the standard catalyst compared.

The results were as follows:

Impregnated solution of palladium chloride and hydrochloric acid.

The impregnated tablets were dried and calcined at 540 ° C. for one hour.

The obtained palladium-containing catalysts were compared in activity with the standard catalyst compared; the results were as follows:

sample

C2
C 2-2

Bulk density
of the pre-compacted material
(g / cm ³ )

0.70
0.66

Pd

Cl

(Weight percent)

0.58
0.58

0.50
0.45

Volume activity

50
80

Catalyst E1 is considerably more active than catalyst E.

Example 8

2400 g of active aluminum oxide C 2 in the form of 3-3 mm tablets were mixed with 3100 ml of 5.2N hydrochloric acid treated. After washing and drying, the tablets were calcined at 780 ° C. for 10 hours. That obtained product, designated as C 2-2, and the original alumina C 2 were with a Although both activities are well below the standard catalyst level, the advantage is of aluminum oxide C 2-2 compared to aluminum oxide C 2 is evident.

Claims (1)

Claim: Process for improving catalyst supports made from optionally shaped, at temperatures between 450 and 850 ° C calcined aluminum oxide through an acid treatment, thereby characterized in that the calcined aluminum oxide is treated with an acid, in particular hydrochloric acid until at most 20% of the aluminum oxide is dissolved, whereupon the acidic solution is separated off, the aluminum oxide was washed out, dried and calcined at 500 to 850 ° C. Considered publications:
German Patent Nos. 864863, 1014689;
U.S. Patent No. 2,550,531. © 909 767/393 3.60