FI65798C - FOERFARANDE FOER REFORMERING AV EN BERGOLJEFRAKTION INNEHAOLLANDE SMAO MAENGDER SVAVEL UNDER ANVAENDNING AV EN KATALYSATORINNEHAOLLANDE MERA RENIUM AEN PLATINA - Google Patents

Description

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Patent · och registrarstyralsen ^ Aiw6k »i ud * d tdiaMrlftM 30.0 3.8 (32) (33) (31) swetlcsw BsgIN ***** 10.04.78 USA (US) 894890 (71) Engelhard Corporation, 70 Wood Avenue South, Iselin , New Jersey 08830, USA (72) James P. Gallagher, Park Forest, Illinois, Robert M. Yarrington,

Westfield, New Jersey, USA (74) Oy Koister Ab (54) Process for reforming a small amount of sulfur-containing petroleum fraction using a more rhenium-than-platinum catalyst - För-farande för reformering av en bergoljefraktion innehällande smä mängder svavel under användning av en catalyst innehlllande mera rhenium a platinum

The invention relates to a new process for reforming a petroleum fraction having a sulfur content of less than about 0.5 ppm by weight of sulfur, which process comprises contacting a petroleum fraction with a catalyst combination consisting of support, rhenium and platinum under reforming conditions and in the presence of gaseous hydrogen.

Catalytic reforming of petroleum is widely used in the petroleum refining industry to produce motor fuels with a greatly increased octane number compared to the petroleum feedstock, as well as aromatics, especially benzene, toluene and xylenes. The improvement in octane number is especially important when metal-containing additives such as tetraethyl lead (TEL) are not used for environmental reasons. The test octane number of a motor fuel that does not contain such additives is determined by ASTM Test No. D-2699 ("clear" or F-1 octane number).

Most reforming catalysts use platinum or a mixture of rhenium and platinum as the catalyst. Platinum is approx.

7-10 times as expensive as rhenium, which is also an expensive metal, and thus the reforming catalyst is one of the most expensive catalysts used in petroleum refining. Any improvements that reduce catalyst costs, such as increasing catalyst life, as well as increasing catalyst life cycle length, are thus highly desirable.

It should be noted that the Soviet Union and South Africa produce more than 95% of the world's platinum. For this reason, too, platinum consumption should be kept to a minimum.

The original commercial noble metal catalysts have used a platinum group metal, preferably platinum itself, as a catalyst; see. e.g., U.S. Patent Nos. 2,479,109 and 2,479,110. In 1968, the transition to alloys of rhenium and platinum. Numerous literature references can be found for rhenium-platinum catalysts. According to U.S. Patent No. 3,415,737, "it is preferred that the rhenium / platinum atomic ratio be about 0.2 to 2.0. It is particularly preferred that the rhenium / platinum atomic ratio not exceed 1. Larger rhenium / platinum ratios (i.e., greater than 1) can be used, but generally no significant additional improvement is achieved. " (column 5, rows 51-56). Further, according to this patent, the amount of platinum and rhenium may range from 0.01 to 3 and 0.01 to 5% (column 5, lines 35 to 48). The reasons for using a low rhenium / platinum ratio are given in column 4 of the patent. The patent also states that the petroleum feed should be substantially free of sulfur, preferably less than 5 ppm (parts per million) and even more preferably less than 1 ppm sulfur (column 7, rows 67 and 69). It should be noted that all concentrations, as used herein, expressed as percentages or parts per million, are by weight unless otherwise indicated (since the atomic weights of rhenium and platinum differ only slightly, the atomic ratio 1 corresponds to a rhenium / platinum weight ratio of 0.955).

U.S. Patent No. 3,558,477, No. 3,679,798, states: "For purposes of this invention, it is essential that the atomic ratio of rhenium to platinum not exceed 1.0. That is, the ratio of rhenium to platinum atoms should be 1, 0 or less. Even more preferably, the atomic ratio of rhenium to platinum should be less than 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). This patent discloses the same amounts of rhenium and platinum in the catalyst combination and the amount of sulfur in the oil as U.S. Patent No. 3,415,737; see. column 1, row 62 and column 7, rows 48-51).

The same information on the ratio of rhenium to platinum and the total amount of rhenium is either repeated or referred to in U.S. Patent No. 3,449,237 (column 3, lines 1-24), U.S. Patent No. 3,558,479 (column 5, lines 50). - 69) and U.S. Patent No. 3,578,582 (column 1, line 45). U.S. Patent No. 3,578,582 also discloses that rhenium-platinum reforming catalysts can be presulfided by treating the fresh catalyst, prior to use in reforming, with hydrogen sulfide or alkyl mercaptan in an amount sufficient to add 0.05 to 2 moles, preferably 0.1 - 1 mole of sulfur per mole of rhenium and platinum (column 2, row 68 - column 3, row 12).

U.S. Patent No. 3,587,583 discloses a small amount (less than 0.1%) of iridium for incorporation into a catalyst having less than 0.3% rhenium and less than 0.3% platinum.

Haensel, Pollitzer, and Hayer, in their New Developments in Reforming, present Proceedings of the Eighth World Petroleum Congress, Vol. 4, p. 255-261 (1971) that the yield of the C ^ + product reaches a maximum when the proportion of rhenium is 50% of the total catalyst metal (i.e. the rhenium / platinum weight ratio is 1), and that the yield of the C ^ + product decreases when the ratio of rhenium platinum either increases or decreases. It states that "the ratio / writing shown in Figure 57 is true over a fairly wide range of platinum content, indicating that the modifying effect of rhenium has indeed affected platinum".

Thus, in the reforming technique, it has been persistently maintained that the ratio of rhenium to platinum should be less than 2 and preferably about 1.

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It has now surprisingly been found that the cycle length of a rhenium-platinum reforming catalyst is substantially extended when the rhenium / platinum ratio is above 2 and below 5, preferably from 2.25 to 4, and most preferably n.

2.5 to 3.5, and when using a petroleum feed having less than about 0.5 ppm and preferably no more than about 0.25 ppm sulfur.

It is surprising that with high rhenium / platinum ratios, i.e. above 5, the cycle length is shortened again. The catalyst combination of the invention contains rhenium and platinum on a support, and the weight ratio of rhenium to platinum is in the above range.

The new catalyst combination can be prepared in the same manner as has hitherto been known for the preparation of catalysts with a lower rhenium / platinum ratio. The amount of platinum may be from about 0.1 to 2%, preferably from about 0.1 to 0.4%, with the rhenium content being set so as to obtain the desired rhenium / platinum ratio over a given range. Kännin is typically etha- or gamma-alumina and may optionally contain silica, manganese oxide, rare earth oxides and synthetic alloys. Typically, the catalyst combination contains about 1% halides, especially chloride or fluoride.

The catalyst is preferably pre-sulfided before use in the reforming to avoid excessive hydrocracking at an early stage in the process. The pre-sulfidation treatment is carried out by contacting the catalyst with a gas stream containing hydrogen sulphide, alkyl mercaptan or carbon disulphide, preferably mixed with gaseous hydrogen, until the catalyst contains about 0.1 to 0.5 parts by weight of sulfur per part of rhenium, i.e. about 0.6 - about 3 moles of sulfur per mole of rhenium. Preferably, no more than about 0.25 parts of sulfur per part of rhenium in the pre-sulfidation step is introduced into the catalyst, e.g. about 0.17 parts of sulfur per part of rhenium.

The reforming process with this new catalyst is essentially the same as known catalysts with a lower rhenium / platinum ratio, except that the sulfur content of the petroleum feed should be less than about 0.5 ppm, and preferably not greater than about 0.25 ppm, for better catalyst life and equivalent To obtain the yield of the C ^ + product. Normally, the petroleum feed is treated with water or otherwise desulphurized by known methods.

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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 petroleum feed and / or the recovered hydrogen gas stream entering the reaction zone of the reformer. The amount of water in the reaction zone should be set to maintain a water / chloride molar ratio between about 20 and 80, preferably about 40: 1.

The activity of the catalyst combination decreases due to the accumulation of carbon deposits, commonly referred to as "coke". The new catalyst combination can be regenerated by methods known in the art. As the new combination is characterized by the fact that a large amount of coke can accumulate on it before the activity decreases to an unsatisfactory level (decrease in C ^ + product yield and / or decrease in F-1 octane number), the regeneration process requires some more time and it is important that precautions known in the art are taken to avoid high flash points during the regeneration step, as local overheating may cause catalyst damage.

The following examples illustrate the invention.

Example 1

A series of (A - H) reforming catalysts were prepared in which the weight ratios of rhenium to platinum varied. The method of preparation of the catalyst used is known and is only briefly described here on a general basis. According to the preparation method, stoichiometrically desired amounts of ammonium rhenate (NH 4 ReO 2) and diammonium chloroplatinate ((NH 4) 2 PtCl 2) and deionized water were placed in the glass. Aqueous ammonium hydroxide was added and the reaction mixture was heated to 81-83 ° C with stirring until all ingredients were dissolved. 10% Hydrogen chloride solution and deionized water were added. The solution was heated to 90-94 ° C. The mixture was poured onto the desired amount of 1.6 mm gamma alumina burst in a rapidly rotating dish. After one minute or less, the plate was stopped and the alumina burrs were removed and covered with a watch glass. The burrs were kept for 1 hour at 40 ° C to 65 ° C (infrared lamp), stirring occasionally by hand. The catalyst was then air dried at 105-115 ° C. The catalyst was then calcined in dry air, which changed at a rate of about 1,000 times per hour for 2 hours at 99 ° C and then for 2 hours at 480 ° C.

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Analyzes of the catalyst combinations are shown in Table I.

Table I

Catalyst Composition,% by weight Weight ratio combination 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 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

The above catalysts were used in reforming experiments under experimental accelerated aging conditions to determine the relative cycle length, per unit weight of platinum, as a function of the rhenium / platinum weight ratio. Midland crude oil was used, with the petroleum fraction treated with water to a sulfur content of 0.21 ppm by weight. The characteristics of the petroleum fraction were as follows:

Density, ° API 54.8

Boiling points of fractions, ° C Initially 110 10% 119 50% 131 90% 157 95% 163

At the end of 188

Sulfur 0.21 ppm

Nitrogen 0.3 ppm

Type analysis (by mass spectrometry) paraffins 45.4% naphthenes 42.6% aromatic compounds 12.0% 7 65798

The experimental device was a simple tubular reactor (25 mm nominal-diameter stainless steel tube) operated isothermally. About 40 g of catalyst was added to it for the reforming experiments. After the freshly prepared catalyst was introduced into the reactor, the catalyst was chemically reduced by passing hydrogen at 480 ° C through a catalyst bed. The temperature was then lowered to 423 ° C and the catalyst was pre-sulfided by passing a 0.7% v / v hydrogen sulfide mixture through the catalyst bed to a constant sulfur content for each sample to about 0.05% by weight of the catalyst. The preheated naphtha feed was initially introduced at a reactor temperature of 423 ° C, after which the temperature was raised to 496 ° C and kept unchanged during the 300 hour aging experiments. The experimental conditions in the reforming were a temperature of 496 ° C, a -1 feed w / v flow rate of 4 h and a hydrogen / hydrocarbon-molar ratio of 3, and a pressure of 14.1 atmospheres. At the beginning of the experiments, these conditions gave a C 1+ product with a test octane number of about 100 without the addition of tetraethyl lead (RONC) as determined by ASTM Method D-2699. During the reforming experiments, a mixture of methanol and alkyl chloride was injected into the petroleum feed to maintain a constant chloride content (i.e., about 1% by weight) in each catalyst.

The data obtained from the reforming experiments were processed as follows. During the 300-hour reforming experiments, the C 1+ liquid product was collected periodically and its octane number was determined. The measured test octane number was plotted against the time used in the coordinate system and the slope of the octane / time curve was adjusted by known methods to smooth the differences between the octane number of the product at the beginning of the experiment and the intended initial octane number 100. The revised test octane number of the Cc + product was then plotted against the time (in hours) since the start of the reforming experiment, often referred to as the "time from the time of feeding." The slope of the octane / time curve is negative and is the octane decrease ratio, i.e., the time factor of octane deterioration. Its units are RONC / h and for convenience it is often expressed in the form Δ RONC / 100 h. In catalytic reforming, it is desirable to reduce the rate of octane decay and thus a lower absolute value of the slope of the curve indicates a more desirable catalyst.

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Table II lists the rate of aging, as the deterioration of the test octane number per 100 hours for the catalysts studied. Catalyst A, which represents a preferred known rhenium / platinum catalyst, was arbitrarily given a relative cycle length of 1.00 and the relative cycle length of all other catalysts was compared thereto by dividing the aging rate of catalyst A by the aging rate of the catalyst in question. The relative cycle length per unit weight of platinum was determined by dividing the relative cycle length of the catalyst by the weight fraction of platinum in the catalyst (see Table I). The latter figure is important because it demonstrates the efficiency with which expensive platinum is utilized. It can be seen from Table II that the use of rhenium / platinum ratios not less than 2 achieves a longer cycle length and / or better efficiency for the use of platinum than catalysts with a lower Re / Pt ratio. Furthermore, it appears that the present invention surprisingly allows the use of a catalyst containing less platinum (about 0.15%, in catalysts F and G) than has been used commercially heretofore.

Table II

Catalyst- Weight- Aging- Relative Relative Combination Ratio Speed, Cycle LengthSplati-

Re / Pt Δ RONCH / 100 h length nan per unit _______weight A 1.08 2.8 1.00 2.99 B 1.48 2.1 1.33 3.87 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 F 2.44 2, 5 1.12 7.47 G 5.65 3.4 0 , 82 5.47 H 17 33 0.08 1.60 9 65798

Example 2

Catalyst C was compared to Catalyst A, using petroleum feeds with different sulfur contents. The experimental conditions were the same as those shown in Example 1, except that the sulfur content of the feed petroleum fraction was adjusted by adding thiophene to increase the sulfur content to 10 ppm by weight. The results of the aging test using petroleum fractions with a sulfur content of 0.2 to 10 ppm are shown in Table III. As described in Example 1, Catalyst C of the present invention has a slower aging rate than the known Catalyst A. The relative duty cycle length and also the relative duty cycle length per unit weight of platinum are higher for Catalyst C according to the invention than for known Catalyst A at a feed sulfur content of 0.2 ppm, but conversely, if the sulfur content is 10 ppm. These experiments confirm that the sulfur content of the petroleum fraction in the process according to the invention should be less than 0.5 ppm, preferably less than 0.25 ppm.

Table III

Feed- Aging- Relative- Relative Usage

Catalyst, rate of use cycle length combination sulfur, Aronc / 100 h cycle of platinum per ppm weight per weight 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 C 10 6.2 0.45 1.32 10 65798

Example 3

Catalysts A, C and G were studied in reformation experiments. The properties of the water-treated petroleum fraction obtained from the crude oil of Kes chimera were as follows:

Density, ° API 54.7

Boiling points of fractions, ° C At the beginning 103 10% 117 50% 131 90% 161 95% 173

At the end of 186

Sulfur 0.57 ppm

Nitrogen 0.77 ppm

Type analysis (by mass spectrometry) paraffins 45.5% naphthenes 42.8% aromatics 11.7%

The reforming test apparatus and the fresh catalyst reduction and pre-sulfidation processes were the same as described in Example 1, except that the amount of sulfur added to each catalyst was varied to give about 0.17 parts of sulfur per 1 part by weight of rhenium, according to the following table:

Catalyst Sulfur content, Weight ratio combination weight% S / Re A 0.06 0.166 C 0.15 0.177 G 0.15 0.171 11 65798

Each such catalyst was used for reforming at 480 ° C, 12/3 atmospheric pressure, a hydrogen / hydrocarbon molar ratio of 9, and a feed weight / volume flow rate of 2 to 12, which was varied to set the octane level of the Cc + product to 91 RONC.

D

The experiments were terminated after treating about 300 l of petroleum per kg of catalyst and analyzing the carbon content of the catalyst used. The relevant values are summarized in the following table:

Weight Avg. Yield Carbon used

Catalyst ratio WHSV 91 in R0NC _catalyst_ combination Re / Pt 91 in RNNC wt%% by unit weight of platinum catalyst 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 WHSV = feed weight / volume flow rate, Rh **.

The activities of the catalysts, expressed as the rate of hourly liquid passing through the catalyst by weight and the yield of the C, - + product, were approximately the same for the catalysts, although the initial sulfur concentrations varied. In addition, the reduction in the amount of carbon (often referred to as coke) in the catalysts used as the rhenium / platinum ratio increases indicates that rhenium provides a kind of cleaning effect that is consistent with the greater relative cycle length available for catalysts with rhenium / platinum. the platinum ratio has increased relative to previous catalysts in the art.

Claims (7)

12 65798 A process for reforming a petroleum fraction having a sulfur content of less than about 0.5 ppm sulfur by weight, comprising contacting the petroleum fraction under a reforming condition and in the presence of gaseous hydrogen with a catalyst composition consisting of a support, rhenium and platinum, characterized in that the weight ratio of rhenium to platinum is more than 2 and less than 5. Process according to Claim 1, characterized in that the weight ratio of rhenium to platinum is from 2.25 to 4. Process according to Claim 1, characterized in that the catalyst combination is pre-sulphidated before the reforming cycle sufficiently to give about 0.1 to 0.5 parts by weight of sulfur per part of rhenium. Process according to Claim 1, characterized in that the sulfur content of the petroleum feed does not exceed about 0.25 ppm by weight. Catalyst combination for use in the process according to claim 1, consisting of a support, rhenium and platinum, characterized in that the weight ratio of rhenium to platinum is more than 2 and less than 5. Combination according to Claim 5, characterized in that the ratio is from 2.25 to 4. Combination according to Claim 5, characterized in that the inverter is predominantly ethane and / or gamma alumina and contains about 1% of halide.