DK149692B - PROCEDURE FOR CATALYTICAL REFORM OF NAFTA WITH A RHENIUM PLATIN CATALYST, AND SUCH A CATALYST - Google Patents

Description

149692 i

The invention relates to a process for reforming a naphtha fraction in which the naphtha fraction is contacted, under reforming conditions and in the presence of gaseous hydrogen, with a catalytic material consisting essentially of an alumina carrier, a smaller catalytically effective amount of at least one halogen component. rhenium and platinum. The invention further relates to catalytic material consisting essentially of an alumina support, a smaller, catalytically effective amount of at least one halogen composerite, rhenium and platinum.

Catalytic reforming of naphtha is extensively used in the petroleum refining industry to produce starting material for engine fuel with a greatly increased octane number relative to the crude naphtha and for the production of aromatics, especially benzene, toluene and xylenes. The improvement in octane number is especially important when metal-containing additives such as tetraethyl lead (TE3) are not used for environmental reasons. The research octane number 20 of a starting material or motor fuel free of such additives is determined by ASTM sample no.

D-2699 and is often referred to as "clear" or F-1 octane light. Advances in the production of unleaded motor fuel are of particular environmental importance.

Most reforming catalysts use platinum as a catalytic agent. Some also use rhenium with platinum. Both metals are expensive, although platinum is approx. 7-10 times as expensive as rhenium, which is why reforming catalyst is one of the most expensive catalysts used in petroleum refining. Any improvement that lowers catalyst costs per unit reformed-naphtha, such as by increasing the catalyst life (i.e., increasing the amount of naphtha that can be reformed per unit weight of catalyst before the catalyst becomes so deactivated that replacement is required) is advantageous.

This is also true with regard to increasing the cycle length of the catalyst, ie. increase the amount of 149692 2 naphtha that can be reformed per weight unit catalyst before the catalyst requires regeneration.

Furthermore, the sources of more than 95% of the world's free platinum supply are in Russia and South 5 Africa. Any improvement that lowers the industry's need for platinum, again, for example, by increasing the lifetime of reforming catalysts containing platinum while still performing the industrial purpose, is a contribution to national security and, moreover, to economic sustainability. dependence.

The original costly commercial catalysts used a platinum group metal, preferably platinum itself, as a catalytic agent, see e.g. U.S. Patents Nos. 2,479,109 and 2,479,110. Around 1968, the use of rhenium was introduced with platinum. A number of references refer to rhenium-platinum catalysts. In U.S. Patent No. 3,415,737, it is stated that: "It is preferred that the rhenium / platinum atom ratio be from about 0.2 to about 2.0. It is further preferred that the atomic ratio of rhenium to platinum does not exceed one . Higher ratios (i.e. greater than one) between rhenium and platinum can be used, but in general no further remarkable improvement is achieved. " (Column 5 lines 51-56).

25

Within this range, the amount of platinum and rhenium according to the patent can be varied, respectively, in the range of 0.01 to 3 and 0.01 to 5% of the catalytic composition. (Column 5 lines 35-48). The reasons for using a low ratio of rhenium to platinum are stated in column 4. In the patent, the patent further states that the crude naphtha should be substantially free of sulfur preferably less than 5 ppm and even better less than 1 ppm. (Column 7 lines 67-69).

35 (In this specification, all compositions expressed in percent or parts per million (ppm) will be by weight unless otherwise stated.) Because rheni- 3 1496-92 twelve and platinum atomic weights differ only slightly, an atomic ratio of 1 the same as a rhenium / platinum weight ratio of 0.955).

In the disclosure to US Patent No. 3,558,477 it is stated that: "It is essential for the purpose of the invention that the atomic ratio of rhenium and platinum is not greater than 1.0. That is, rhenium / platinum atom ratio should be 1.0 or less than 1.0.

Even better, the rhenium / platinum atom ratio should be less than approx. 0.7. Since rhenium and platinum have almost the same atomic weight, the atomic ratio is essentially the same as the weight ratio "(column 3 lines 26-33).

15

The patent also discloses the same amounts of rhenium and platinum in the catalytic mixture and sulfur in the naphtha as U.S. Patent No. 3,415,737, see column 1 line 62 and column 7 line 48-51.

The conclusions regarding the rhenium / platinum ratio and the total amount of rhenium disclosed in the above-mentioned United States Patent No. 3,415,737 are either repeated or expressly incorporated herein by reference in U.S. Patent

3,449,237 in column 3 lines 1-24, in United States Patent No.

3,558,479 in column 5 lines 50-69 and in United States patent no.

3,578,582 in column 1 line 45. In the description to the United States

Patent No. 3,578,582 further states that rhenium platinum reforming catalysts can be presulfated by treating fresh catalyst before being used in the reforming with hydrogen sulfide or an alkyl mercaptan in sufficient quantity to add 0.05 to 2 moles, preferably 0, 1 to 1 mole of sulfur per mole of rhenium and platinum, see column 2 line 68 to column 3 line 12.

In U.S. Patent No. 3,578,583, the specification discloses the introduction of a minor amount, up to 0.1%, of iridium 35 into a catalyst having up to 0.3% of both rhenium and platinum.

4 149832 In an article entitled "New Developments In Reforming" by Haensel, Pollitzer & Hayes (of Universal Oil Products Company), in "Proceedings of the Eighth World Petroleum Congress", Vol. 4 pages 255-261 (1971) 5, that the yield of C ^ + liquid product reformate reaches a maximum when rhenium constitutes 50% of the total catalytic metal (i.e., a rhenium / platinum weight ratio of 1) and the yield of liquid product reformate thereafter decreases as the relative weight of rhenium to platinum 10 either increase or decrease. It is stated that "The ratio shown (in Fig. 5 of the article) is correct within a fairly wide range of platinum content, which indicates that the rhenium's modifying effect is performed on the platinum." Ibid, pages 259-60.

Danish Patent Specification No. 141606 discloses a process for reforming a hydrocarbon using a catalyst comprising alumina, a metallic component of the plate group, a halogen component and a rhenium component, stating that for the rhenium component and the plate group component, each is present in amounts of from ca. 0.05 to approx.

1.0% by weight.

Furthermore, in Claim 6, a composite catalyst is disclosed wherein the weight ratio of the rhenium to the platinum group component is from about 1 to about 1. 0.05: 1 to approx.

2.75: 1st

The working examples show catalysts with Re / Pt weight ratios of between 0.13 and 0.36 (Re content of 0.1 to 0.2% by weight and Pt content of 0.55 to 30. 0.75), ie . with predominantly platinum content.

British Patent Nos. 1,269,764 and 1,269,765 disclose the use of catalysts for said use, where the Re / Pt ratio is in the range of 0.2-5. In the exemplary embodiments, the highest 35 Re / Pt weight ratio has a value of 1

It can be seen from this that in the reforming technique with rhenium-platinum catalysts, it has been consistently stated that the rhenium / platinum ratio should be less than 2 and preferably approx. 1 or less «5 U9B92 In the case of higher Re / Pt weight ratios, there is no relationship between the sulfur content of the naphtha to be reformed, the Re / Pt weight ratio of the specified catalyst and the achievable cycle length.

Surprisingly, it has now been found that the cycle length of a rhenium-platinum reforming catalyst is significantly increased if the rhenium-platinum ratio is in the range of not less than 2 to approx. 5, preferably in the range of approx. 2 1/4 to approx. 4 and even better in the area from approx.

10 2½ to 3% when using a raw naphtha with a sulfur content that is less endile reduced to approx. 0.5 ppn and preferably not greater than about 0.25 ppri. This progress is not only beyond the teachings of the prior art, but is a unique optimum since the cycle length at very high rhenium / platinum ratios, about above 5, also decreases.

The new catalyst is a catalytic mixture consisting of rhenium and platinum on a carrier, wherein the weight ratio of rhenium to platinum is in the range indicated above.

In accordance with the foregoing, the process of the invention is peculiar in that the naphtha fraction, prior to contact with the catalyst, is desulfurized to a sulfur content of less than ca.

0.5 ppm sulfur by weight, the platinum content is between 0.1 and 0.4% by weight, and the weight ratio of rhenium to platinum in the catalytic material is in the range of not less than 2 to approx. 5th

Similarly, the catalytic material according to the invention is characterized in that the platinum content is between 0.1 and 0.4% by weight and that the weight ratio of rhenium to platinum in the catalytic material is in the range of not less than 2 to approx. 5th

Various suitable embodiments of the process and the catalytic material of the invention can be used, as set forth in claims 2-4 and 6-7.

6 143692

Apart from the increased rhenium / platinum weight ratio, the catalytic mixture of the invention may be prepared in the prior art as known to produce lower rhenium / platinum catalysts. The amount of platinum may be in the range of approx. 0.1 to approx.

2%, preferably in the range of approx. 0.1 to 0.4% with the rhenium content adjusted to obtain the desired rhenium / platinum ratio within the range indicated. The carrier is typically η or γ alumina and may optionally contain silica, magnesium oxide, rare earth oxides and synthetic zeolites, sometimes referred to as molecular sieves. Typically, up to approx. 1% of the catalytic mixture of halides especially chloride or fluoride.

It is preferred that the catalyst be presulfated before use in reforming to avoid excessive hydrogen cracking when the catalyst is first placed in the feed stream. The pre-sulfidation treatment is carried out by contacting the catalyst with a gas stream containing 2Q containing hydrogen sulfide, an alkyl mercaptan or carbon disulfide, preferably mixed with gaseous hydrogen until the catalyst contains from ca. 0.1 to approx.

0.5 parts by weight of sulfur. part by weight of rhenium, ie in the area from approx. 0.6 to approx. 3 moles of sulfur per mol of rhenium. It is preferred that the catalyst be supplied with no more than approx.

0.25 parts by weight of sulfur per liter. part by weight of rhenium in the presulfurization step, e.g. ca. 0.17 parts by weight of sulfur per liter. part by weight of rhenium.

The reforming process with the new catalyst is essentially the same as with the prior art type of catalyst having a lower rhenium / platinum ratio, except that the crude naphtha should have a sulfur content less than or reduced to about 10%. 0.5 ppm and preferably not greater than Q, 25pprr. to obtain the superior catalyst lifetime and an approximate equivalent yield of C5 + liquid reformate obtainable with a catalyst having a rhenium / platinum ratio in the range of about 2 1/4 to approx.

5. X is generally hydrogen treated or desulfurized by the known methods. Although the prior art discloses the use of naphtha with less than 1 ppm sulfur, the catalysts of the invention require naphtha with the very low sulfur content stated above.

Halides can be added to the reaction zone during the reforming, such as by injecting hydrogen chloride, carbon tetrachloride or an alkyl halide into the naphtha feed stream and / or into the return hydrogen gas stream entering the reaction zone of the reformer. The amount 10 of water in the reaction zone should be adjusted to maintain a water to chloride molar ratio in the range of about 20 to 80, preferably 40: 1.

When the effect of the catalytic mixture is decreased due to an accumulation of carbonaceous deposits commonly referred to as "coke", the catalyst can be regenerated by known methods. However, it is a peculiarity of the catalyst having a rhenium / platinum ratio within the range of the invention that a greater amount of "coke" can be accumulated thereon before the activity drops to an unsatisfactory level, which is indicated by reduction in yield of C5 + reformate and / or reformate clear octane number than catalysts having a rhenium / platinum ratio of less than 2. Thus, the regeneration process will require some more time and known precautions should be taken to avoid excessive flame-mefront temperature during regeneration to avoid damage to the catalyst due to local overheating.

The remarkable improvement in catalyst 3Q cycle length has been established by laboratory test data described in the following examples. The examples are set forth to illustrate the preparation of catalysts useful in the process of the invention and their use in the catalytic reforming of naphtha.

149692 8

Example 1

A number of reforming catalysts having different weight ratios of rhenium to platinum are produced.

The method used to prepare the catalyst is known and will only be described briefly below on a general basis. The preparation process consisted of adding to the beaker the desired stoichiometric amounts of ammonium perrhenate (NH4 ReO4) and diammonium hexa-chloroplatinate (XV) ((NH4) 2PtCl2) and deionized water.

Aqueous ammonium hydroxide was added and the reaction mixture was heated by hand, stirring to a temperature in the range of 81-83 ° C, until all ingredients were dissolved and a pale straw yellow color appeared.

A 10% * aqueous HCl solution and more deionized water were added. The solution was then heated to 90-94 ° C.

The mixture was then poured in addition to the desired amount of 1.6 mm γ-alumina extrudates placed in a rapidly rotating dish. After approx. For 1 minute or less 2g, the alumina extrudates were removed from the dish and covered with a watch glass. The extrudates were kept in lutime at a temperature of at least 40 ° C and up to a maximum of approx.

65 ° C by means of an infrared lamp and stirred in by hand. The catalyst was then dried with air at 105-115 ° C. Then, the catalyst was calcined in dry air flowing at a rate of ca.

1000 V / V / hour for 2 hours at 99 ° C and then for 2 hours at 480 ° C.

The analytical composition of catalysts A-H is shown in Table 1.

30 9

Table 1 149692

Comparison Weight Percent Weight Assumption Team 5 Catalyst Pt Re Cl Re / Pt A 0.334 0.362 0.91 1.08 B 0.344 0.510 0.80 1.48 C 0.340 0.849 0.93 2.50 D 0.248 0.516 0.99 2, 08 10 E 0.236 0.860 0.97 3.64 F 0.150 0.366 0.98 2.44 G 0.155 0.875 0.98 5.65 H 0.05 0.85 1.0 17 15

The above catalysts were used in reforming test plant experiments under accelerated aging conditions to determine the relative cycle length per weight unit of platinum as a function of the rhenium / platinum weight ratio. A naphtha from a Middle Continental crude oil was used, the naphtha having been hydrogen treated to give a sulfur content of 0.21ppm by weight. The properties of Naphtha are listed below.

0 5 <*>

Density, (save, 16.5 ° C) 0.760

Distillation beginning bp, ° c 110 10% 119 30 50% 131 90% 157 95¾ 162 End point 188 35 Sulfur, ppm .0.21 nitrogen, ppm 0.3 149692 10

Type Analysis (with Mass Spectrometer) Paraffins 45.4% Naphthene 42.6% Aromatics 12.0% S The test plant consisted of a simple tubular stainless steel reactor with a nominal 2.54cm internal diameter, which was operated isothermally. 40 grams of catalyst for the reform studies. After a freshly prepared catalyst was placed in the reactor, the catalyst was chemically reduced by allowing hydrogen to flow through the catalyst layer at 480 ° C. The temperature was then lowered to 425 ° C and the catalyst presulfated by passing a mixture of 0.7 volume percent hydrogen sulfide in hydrogen through the catalyst layer until a constant sulfur level was obtained for each sample of approx. 0.05% by weight of the catalyst.

The preheated raw anaphtha was initially introduced at a reactor temperature of 425 ° C, after which the temperature was increased to 495 ° C and kept constant for the duration of the 20 300-hour aging test. ) at 4 hours, a hydrogen / hydrocarbon mole ratio of 3 and a pressure of 15 atm. These conditions at the beginning of the experiments produced a C5 + re-25 format with a research octane number without the addition of tetraethyl lead (referred to as RONC) of approx. 100, determined by ASTM Procedure No. D-2699. During the reforming studies, a mixture of methanol and alkyl chloride was injected into the crude naphtha to maintain a constant (i.e., about 20% by weight) chloride content on each catalyst.

The data from the reform experiments were processed as follows. X during the 300-hour reform studies, the C 2+ liquid product was collected at intervals and its octane number examined. The measured research octane number was plotted against time in the feed stream, and the slope of the octane time curve was adjusted by known methods to compensate for any difference between the reformed octane number at the beginning of the study and the desired initial octane number of 100. The reformat's compensated research octane number was then plotted against the time in hours that had passed since the start of the reform study, often referred to as "time on feed". The slope of the octane time curve is negative and indicates the rate of octane lowering, i.e. the rate at which the octane number decreases. It has the unit RONC / hour and is often listed for convenience as ARONC / IOO hours. In catalytic reforming, it is desirable to minimize the octane lowering rate, and a lower absolute value on the slope of the curve therefore indicates a more desirable catalyst.

Table II indicates the slope rate as the decrease in the research octane per 100 hours for the under-15 catalysts searched. Catalyst A, representative of the previously known preferred rhenium / platinum catalysts, was arbitrarily assigned a relative cycle length of 1.00 and the relative cycle lengths of all remaining catalysts compared to that by dividing the 2q slope rate of catalyst A by the slope of the considered catalyst. The relative cycle length per weight unit platinum was determined by dividing the relative cycle length of a catalyst by the weight part platinum of the catalyst (as listed in Table 1). The 2 ^ last calculation is significant as it indicates the efficiency with which the precious platinum is used. The results in Table 2 show that by using rhenium / platinum ratios of not less than 2, a longer cycle length and / or better efficiency can be achieved in the use of platinum than in catalysts having a lower Re / Pt ratio. Furthermore, the results surprisingly state that, according to the invention, catalysts containing a lower part by weight of platinum (about 0.151 in catalysts P and G) can be used than have been commercially used so far.

Table 2 149692 12 Weight Maturity Relative Relative cycle holding speed cycle length per unit.

length weight unit 5 platinum

Catalyst Re / Pt ARONC / IOO

hours A 1.08 2.8 1.00 2.99 B 1.48 2.1 1.33 3.87 10 C 2.50 1.7 1.65 4.85 D 2.08 2.2 1, 27 5.12 E 3.64 1.9 1.47 6.23 P 2.44 2.5 1.12 7.47 G 5.65 3.4 0.82 5.47 15 H 17 33 0.08 1.60

Example 2

Catalyst C was compared to Catalyst A

20 using robber naphtha with different sulfur content. The test conditions were the same as in Example 1 except that the sulfur content of the crude naphtha was adjusted by adding thiophene to increase the sulfur content to 100ppm by weight. The results from the aging study using crude naphtha with sulfur content of 0.2 and 100ppm are given in Table 3. As shown in Example 1, catalyst C of the invention has a lower curing rate than the known catalyst A. The relative cycle length and also the relative cycle length per the unit weight of platinum of catalyst C, according to the invention, is greater than that of the known catalyst A when the sulfur content of the crude naphtha is 0.2ppm but vice versa if the sulfur content is 10ppm. These results state that for optimal utilization of the present invention, the sulfur content of the raw naphtha should be reduced to less than 0.5 and preferably to less than 0.25 ppm.

Table 3 149692 13

Catalyst Rånaphtha- Aging Relative Relative sulfur, ppm speed cycle cycle 5 ARONC / IOO length length per.

hours weight unit platinum A 0.21 2.8 1.00 2.99 A 10 4.0 0.70 2.10 C 0.21 1.7 1.65 4.85 10 C 10 6.2 0.45 1 , 32

Example 3

Catalysts A, C and G were used in reforming pilot plant studies which further elucidate the process of the invention. The hydrogen-treated naphtha from a Middle Continental crude had the following characteristics: Density, (gcm? I6.5 ° C) 0.761

Distillation starting bp, ° C 103 10% 117 25 50% 131 90% 161 95% 173

End point 185

Sulfur 0.57 ppm

3Q

nitrogen 0.77 ppm

Type Analysis (with Mass Spectrometer) Paraffins 45.5 Naphthenes 42.8 35 Aromatics 11 # 7

The reforming pilot plant and the methods for reducing and presulfating the fresh catalysts were the same as described in Example 1, except that the amount of sulfur added to each catalyst varied to give approx. 0.17 parts sulfur per part by weight of rhenium as set out in the following table.

Catalyst Sulfur on Weight Ratio Catalyst, S / Re weight percent 10 - - - A 0.06 0.166 C 0.15 0.177 G o, 15 0.171 15

Each of these catalysts is used for reforming at a temperature of 480 ° C at a pressure of 13.3 atm. a hydrogen / hydrocarbon molar ratio of 9 and a volura velocity in the range of 2 to 12 hours1, which was adjusted to adjust the octane level of the C₂ + reformate of 91 RONC.

The experiments were completed after approx. 7Q0 liters of naphtha per day.

kg of catalyst had been treated and the catalysts used were analyzed for carbon content. The relevant data are listed below: 25 Weight- Medium Reformat- Carbon on used cat-

Catalyst ratio WHSV at yield lysator_

Re / Pt 91 RONC at 91% by weight%

RONC catalyst watch unit timer130 A 1.08 7.0 87.6 1.15 3.44 C 2.5 6.7 85.8 0.49 1.44 G 5.65 6.0 85.6 0.28 1.81 149692 15

The activities of the catalysts, as indicated by weight / volume velocity and the yield of C5 + reformate, were approximately similar for the catalysts, although the initial sulfur content was different. Furthermore, the reduction in the amount of carbon (often referred to as the "coke") of the catalysts used by an increase in the rhenium / platinum ratio indicates that rhenium exerts an "on-stream" purifying effect consistent with the larger relative cycle length obtainable with catalysts having a higher Re / Pc ratio compared to prior art catalysts.

Claims (6)

149692 A process for reforming a naphtha fraction in which the naphtha fraction is brought into contact with a catalytic material consisting essentially of an alumina carrier under a reforming conditions and in the presence of gaseous hydrogen, a smaller catalytically effective amount of at least one halogen component, rhenium and platinum, characterized in that the naphtha fraction, prior to contact with the catalyst 10, is desulfurized to a sulfur content of less than approx. 0.5 ppm sulfur by weight, the platinum content is between 0.1 and 0.4% by weight, and the weight ratio of rhenium to platinum in the catalytic material is in the range of not less than 2 to approx. 5th Process according to Claim 1, characterized in that the weight ratio of rhenium to platinum is in the range between approx. 2 1/4 to approx. 4th Process according to claim 1, characterized in that the catalytic material is sufficiently presulphidated to provide this between 0.1 and approx. 0.5 parts by weight of sulfur. part by weight of rhenium prior to the reformation cycle. Process according to Claim 1, characterized in that the sulfur content of the wafer aperture prior to contact with the catalyst is not greater than approx. 0.25 ppm by weight. 5. Catalytic material consisting essentially of an alumina carrier, a minor catalytic effective amount of at least one halogen component, rhenium 30 and platinum, k characterized in that the platinum content is between 0.1 and 0.4% by weight and that the weight ratio of rhenium to platinum in the catalytic material is in the range of not less than 2 to approx. 5th 6. Catalytic material according to claim 5, characterized in that the rhenium / platinum weight ratio is in the range of approx. 2 1/4 to approx. 4th