NL8300053A - METHOD FOR SELECTIVELY PRODUCING MIDDLE DISTILLATE HYDROCARBONS. - Google Patents

Description

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A method for the selective production of middle distillate hydrocarbons

Sen of the most important features! what a modern refinery should have is flexibility. The ability to use different feeds, ranging from slate and heavy oils to light oils, to produce different product programs in response to changes in consumer demand is critical to profitability. For example, feeds are now shifting to lower-quality, high-boiling mixtures with more metal, nitrogen and sulfur impurities than feeds previously used. Expectations of consumer demand predict shifts of gasoline range hydrocarbons to heavier, higher boiling products such as diesel fuels, fuel oils and turbine fuels. _

Hydrocracking, whether used in a one-step process or in multi-step processes coupled with hydrodesulfurization and hydro-denitrogenation steps, has been widely used to improve poor quality feeds in quality and produce gasoline range products. Over the years, much development work has gone into finding improved hydrocracking conditions and catalysts. Catalysts containing only amorphous materials and catalysts containing zeolites composed with amorphous materials have been used in tests

Among the zeolites described in the literature are Y 25 (U.S. Patent 3 * 130,007), decationized Y

(U.S. Patent 3 * 130,006), Ultrastable Y (U.S. Patent 3 * 293 * 192 and 3 * 449 * 070) and Ultrahydrophobic Y (British Patent 2,014 * 970). There is also literature related to the modification of zeolites. In U.S. Pat. No. 3,368,884, the reduction of superactive zeolite activity is described by a calcination, leaching method. The catalyst is described as particularly suitable for cracking gas oils to gasoline. U.S. Pat. Nos. 3 * 506,400 and 3 * 591 * 488 describe the improvement of the stability of the crystalline lattice of zeolites by a steam and acid extraction process. The 8300053 * 2 product, a stabilized zeolite, can be used in hydrocracking and is described as a zeolite with improved selectivity as evidenced by the higher gasoline yield and lower coke yield.

5 Other research has resulted in publications related to the production of middle distillate products.

U.S. Pat. No. 3,853,72 describes the hydrocracking of high boiling feeds to produce middle distillate products using a catalyst containing a steamed zeolite. U.S. Pat. No. "120,825" also describes the improvement in the production of middle distillate products by hydrocracking with a catalyst containing a steamed zeolite.

It has been found that middle distillate products can be selectively produced by hydroprocessing with an expanded pore zeolite-like catalyst.

The present invention therefore relates to a process for the selective production of middle distillate hydrocarbons comprising (a) contacting a hydrocarbonaceous feed under hydroprocessing conditions boiling above about 316 ° C with a catalyst containing a hydrogenation component . and contains an expanded pore zeolite, said zeolite consisting of a faujasite zeolite which is steamed and then freed from alumina and (b) recovering a hydrocarbonaceous effluent boiling above about ifO vol. # above about 1if9 ° C and below about 371 ° C.

It has been found that faujasite-like zeolites liberated from aluminum-50-minium oxide after high temperature steaming have surprising stability and activity for producing middle distillates from higher boiling feeds. Faujasite-like zeolites are understood to mean crystalline aluminosilicates, synthetic or natural, which have the crystalline structure of the large pore zeolite, faujasite. These zeolites include faujasite, zeolite X, zeolite Y, and zeolites derived therefrom. For example, numerous methods are known in the art for the treatment of zeolite Y to produce "decationized Y", "ultrastable Y", IfO nZlif-SS "and others. The preferred faujasite-like zeolite is zeolite Y, as well as derivative zeolites having the crystal lattice properties of zeolite Y. The most preferred faujasite-like zeolite is an ultra-stable Y zeolite with a sodium content of less then about 0.5 wt. £ 5 (as Na 2 O).

As prepared, the large pore zeolites usually contain sufficient amounts of alkali metal. Since the alkali metals usually poison the acidic sites of the zeolite, standard ion exchange methods are used to remove the alkali metals. The alkali metal content (calculated as oxide) is preferably reduced to below 5 wt% before any heat treatments take place and to less than about 200 wppm in the final zeolite.

The faujasite-like zeolite to be treated is calcined at high temperatures in the presence of water. During this high temperature steam treatment it is desirable that at least 2 wt.% Of the atmosphere above the zeolite is water, preferably more than 10 wt.%, And more preferably more than 25 wt.%. one effective way of calcining the zeolite is to place the zeolite, which has undergone an aqueous ion exchange, in an autoclave and to steam it under autogenous pressure. The temperature of the steam stage is usually above 538 ° C, preferably above 649 ° C and most preferably above 760 ° C. The time of steam calcination can vary from 50 minutes to 24 hours or more.

It has been found that the steam calcination removes aluminum from the crystal lattice and volatilizes silicon to restore the voids left in the lattice by the aluminum. Therefore, the cohesion of the grid 30 is largely maintained and total collapse is avoided. Nevertheless, there is some loss of crystallinity. The steam treatment creates coarse cracks and crevices in the crystalline particles. The aluminum removed from the grid appears to form amorphous alumina deposits in the grid pores and channels. These amorphous deposits are removed by the alumina liberation method. Alumina liberation usually involves leaching the steamed zeolite with organic chelating agents such as EDTA or with organic or inorganic acids. Diluted inorganic acids, in particular hydrochloric and sulfuric acids, are most preferred. When acids are used, the pH of the leaching solution is preferably less than about 2. It will be appreciated that, if the pH is too high, the liberation of aluminum oxide will take an ineffective time while when the acid concentration the crystal lattice of the zeolite is too high to be affected. Usual acid solutions are from about 0.01 normal to about 10 normal.

The final zeolite-like product will have a smaller crystal lattice and a higher silica: alumina molar ratio than is normally obtained. Steamed alumina freed zeolite Y will usually have a cubic cell constant less than about 2.44 nm and a silicon oxide: alumina mole ratio greater than about 10: 1 and most preferably greater than about 20 : 1. The final product freed from aluminum oxide will also have a larger specific surface area than the starting material. The steam / calcination treatment surprisingly also improves the catalytic properties of ultrastable Y zeolites. Even though the alumina content of the steamed / leached faujasite-like zeolites is very low compared to the starting materials, they surprisingly retain activity and obtain considerable selectivity for the valuable middle distillates.

The final catalyst composition contains both the faujasite-like zeolite and an inorganic oxide matrix. Inorganic oxides are standard zeolite supports used in hydroprocessing and may include alumina, silica, magnesia, titanium oxide and combinations thereof. The preferred support is aluminum oxide. A wide variety of methods can be used to combine the zeolite with the refractory oxide. For example, the zeolite can be milled with the hydrogel of the oxide and mixed, if required, followed by partial drying and extruding or granulating to form particles of the desired shape. Also, the refractory oxide can be precipitated in the presence of the zeolite. This is accomplished by raising the pH of the solution of a refractory oxide precursor, such as sodium aluminate or sodium silicate. As described above, the combination can then optionally be partially dried, tabulated, granulated, extruded, or formed with another agent 8300053

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5 and then calcined, for example at a temperature above 316 ° C, usually above if27 ° C. Methods producing larger pore size carriers are preferred over methods producing smaller pore size carriers in cogelation. Also, when the steamed zeolite is added to an acidic solution of an inorganic oxide preproduction, the leaching step can be performed in situ in the cogelation mixture without a separate leaching step.

The catalyst should contain less than about 50 weight percent, preferably less than about 30 weight percent of the zeolite based on the dry weight of zeolite and refractory oxide.

However, the zeolite content should exceed 0.5 wt.% And is usually greater than 2 wt.%. The final catalyst composition contains at least one hydrogenation component. The hydrogenation component is usually a transition metal or a Group IV-A metal and is usually a Group VI-B or VIII metal or combination of metals or their oxides or sulfides.

The hydrogenation components are preferably molybdenum, tungsten, nickel and cobalt metals, oxides and sulfides. The compositions preferably contain more than about 5 wt.%, Preferably about 5 to about 40 wt.% Molybdenum or tungsten or both, and at least about 0.5 and generally about 25 wt.% To about 15 wt.% Nickel or cobalt or both, determined as the corresponding oxides. The catalysts are often pre-sulfided because the use of the sulfide form of these metals results in greater activity, selectivity and activity retention.

The hydrogenation components can be added by any of many rich methods. They can be added either to the zeolite or the support or to a combination of the two. Also, the Group VIII components can be added to the zeolite by mixing and grinding, impregnation, or ion exchange together, and the Group VI components, that is, molybdenum and tungsten, can be combined with the refractory oxide by impregnation, grinding together and mixing or coprecipitation.

The hydrogenation components can be included in the catalyst preparation at any of a number of kO steps. For example

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8300053 - / * 6 image, metal compounds, such as the sulfides, oxides or water-soluble salts, such as ammonium heptamolybdate, ammonium tungstate, nickel nitrate and cobalt sulfate, can be added by grinding and mixing, impregnating or precipitating 3 to the zeolite or refractory oxide or both, before the zeolite is finally calcined and combined with the support or after its final calcination, however, prior to the combination with the refractory oxide. These components can be added to the spent catalyst particle by impregnation with an aqueous or hydrocarbon solution of soluble compounds or precursors.

The hydrocarbonaceous feeds used in these processes primarily boil above about 316 ° C. Preferably, at least about 90% of the feed will boil between about 371 ° C and 649 ° C. Feeds with these properties include gas oils, vacuum gas oils, coked gas oils, deasphalted residues and catalytic cracking cycle stocks. The hydrocracking feed generally contains at least about 3 ppm and usually between about 10 ppm and 0.1 wt. Nitrogen as organo nitrogen compounds. The feed can also contain significant amounts of mono- or polynuclear aromatics, corresponding to at least about 3 and generally about 3 to about ifO vol * aromatics.

Although the catalysts used in these processes exhibit good stability, activity and middle distillate selectivity, the reaction conditions should be related to provide the desired conversion rates while minimizing conversion to less desirable lower boiling products. is becoming. The conditions required to meet these objectives will depend on the catalyst activity and selectivity and the feed properties such as boiling range, as well as the organo nitrogen and the aromatics content and structure. Conditions will also depend on the most judicious compromise of total activity, ie conversion per pass and selectivity. For example, these systems can be used at relatively high conversion rates on the order of 70, 80, even 90 conversion per pass. However, higher conversion rates will result in lower selectivity. Therefore, a compromise must be made between conversion and selective- 8300053 * *. 7 text. Balancing reaction conditions to achieve the desired objectives is part of the conventional art.

Reaction temperatures generally exceed about 260 ° C and are usually above about 316 ° C, preferably between 316 ° C and 482 ° C. Hydrogen addition rates should be at least about 7 * 1 Nm / hl and usually between about 35 and 270 Nm / hl. Reaction pressures exceed 1370 kPa and are usually in the range of about 3240 to 20,700 kPa. Space velocities are less than about 15 *, preferably between about 0.2 and about 10.

The total conversion rate is primarily controlled by the reaction temperature and the space velocity. However, the selectivity is generally inversely proportional to the reaction temperature. It is so heavily influenced by reduced space velocities with otherwise constant conversion. In contrast, selectivity is usually improved at higher pressures and hydrogen addition rates. Thus, the most desirable conditions for the conversion of a specified feed to a predetermined product are best obtained by converting the feed at some different temperatures, pressures, space velocities, and hydrogen addition rates »correlating the effect of each of these variables and choosing the best compromise of total conversion and selectivity.

The conditions should be chosen such that the total conversion rate will correspond to the production of at least about 40% and preferably at least about 50% products boiling below about 371 ° C per pass.

The middle distillate selectivity should be such that at least about 40, preferably at least about 50% of the product is in the middle distillate range. The process can maintain conversion levels greater than 50% per pass at selectivities greater than 60% to middle distillate products boiling between 204 ° C and 371 ° C.

The present process can be carried out as a single-stage hydroprocessing zone. The process may also be the second stage of a two-stage hydrocracking scheme where in the first stage nitrogen and sulfur are removed from the feed before contacting the middle distillate generating catalyst. The present process may also be the first stage of a multi-stage hydrocracking scheme. In the embodiment as the first stage, the middle distillate-generating zone also denitrifies and desulfurizes the feed; in addition, it becomes possible to perform the second stage more efficiently, so that more middle distillates are generated in total than with other process configurations. preference for increasing the middle distillate production.

COST DESCRIPTION OF THE FIGURES

Fig. 1 illustrates the difference in fouling rate and activity between a standard amorphous catalyst used to produce middle distillates and the catalyst used in the invention.

Fig. 2 illustrates the effect of the amount of acid used in the leaching solution on the silica: alumina molar ratio of the zeolite.

Fig. 3 illustrates the effect of the amount of acid 20 used in the leaching solution on the crystallinity of the product zeolite as compared to the zeolite steamed with reagent.

Figures If, 5 and 6 illustrate the superiority of the present invention in producing middle distillate. Catalysts containing steamed / leached, steamed and untreated ultrastable Y zeolites were contrasted. Fig. k illustrates the higher middle distillate diesel yield and the steamed / leached catalyst; FIG. 5 illustrates the lower heavy naphtha yields of the steamed / leached catalyst and FIG. 6 illustrates the lower aromatics content of the middle distillate obtained with the steamed / leached catalyst. The yields are plotted against the conversion at less than 354 ° C

Fig. 7 contrasts the pore size distribution of a steamed and steamed / leached Y zeolite.

Example I

A catalyst containing steamed, leached Y zeolite was compared to a nickel-tungsten, non-zeolite-like catalyst (silica / alumina / titanium oxide bullet base) used to prepare middle distillates to compare activity and fouling rates. The zeolite-like catalyst contained 15 wt. Zeolite steamed at 80 ° C for 1 hour at 802 ° C and washed with 1 normal hydrochloric acid. The zeolite was milled and mixed together with alumina and had a final metal content of 3,99 wt.% Nickel and 20,5 wt.% Tungsten. The feed was a directly obtained heavy Arabian gas oil with the following properties: API 21.8

aniline point 78 ° C

S, wt # 2.62 N, ppm 846 Ί0 distillation (D-1160), ° C: start / 5 332/388 10/30 401/436 50 451 15 70/90 468/499 95 / kpt. 514/540

The reaction conditions were a space velocity of 0.75 and a pressure of 9 ^ 50 kPa and 89 Nm ^ H ^ / hl feed. The results are shown in Figure 1. The zeolite-like catalyst 20 is considerably more active with a considerably slower fouling rate than the nonzeolite-like catalyst.

Example IX

A series of experiments were conducted to investigate the effect of acid washing on the silica: alumina molar ratio and the crystallinity of the zeolite product. The starting material was NH 2 Y with a sodium content of less 1 1 and a silica: alumina molar ratio of 5: 1: 1. The zeolite was steamed at 800 ° C for 1 hour and then washed with acid. The wash solutions were prepared based on volumes of concentrated hydrochloric acid per gram of zeolite (0.8 ml of concentrated HCl is the stoichiometric amount of acid required to increase the SiO 2 / Al 2 O 3 molar ratio from 5: 1 to 30: 1) the measured acid was then diluted to about 1.1 molar or 8.5 molar and the zeolite 35 was washed with the resulting solution. The silica: aluminum oxide molar ratio was determined by neutron activation analysis; percent crystallinity was measured as percent X-ray diffraction intensity with respect to Na-Y. As can be seen from FIGS. 2 and 3, the SiO2 / Al2O2L2 mol mol ratio and percent crystallinity appear to vary linearly and unexpectedly with the amount of acid used to prepare the wash solution rather than with the strength of the wash solution. It is preferable to maintain at least 50% crystallinity as a percentage of X-ray diffraction intensity 5 with respect to Na-Y in the product compared to the starting material.

Example III

A series of experiments were conducted to compare the products obtained with different zeolite-like hydrocracking catalysts. Catalysts A and B were steamed at 800 ° C for 1 hour and Catalyst B was leached with 1 normal hydrochloric acid to remove the alumina residue.

The zeolites were formulated with alumina by mixing and milling together and then extruded. The extrusion product was impregnated with the hydrogenation metals using standard methods. The catalysts had the following properties:

Zeolite catalyst A.. B C

steamed steamed / from ultrasta

ultrastable aluminum bile Y

liberated ultra-stable Y.

wt. # zeolite 15 15 15 wt. # Ni 6.9 4 * 0 3 «4 wt.% W 17 * 2 21.0 20.0 cell constant, nm 2.444 2.1 * 36 2.1 * 58

SiO 2: Al 2 O 5 5: 1 29: 1 5: 1

The catalysts were tested in a single-stage hydrocracking process using a directly obtained arabic light vacuum gas oil feed having the following properties: API 22.9

aniline point 8-1 ° C

S, wt% 2.15 N, ppm 877 25 Distillation (D-1160), ° C: start / 5 339 / 37b 10/30 381/1 * 13 50 448 30 70/90 467/503 95 / kpt. 511/536 8300053 4 11

The reaction conditions included a space velocity of 1.2, a pressure of 10,100 kPa and 89 Nm 2 / hl feed recycle gas.

The highly desirable product properties obtained by the present process are illustrated in Figures 4, 5 and 6.

The steamed / leached zeolite produces considerably more middle distillate (Fig. 4) of a lower aromatics content (Fig. 6) than the steamed and untreated Y zeolite. In addition, cracking of the feed to naphtha range products occurs to a significantly lesser extent (FIG. 5) with the steamed / alumina-free zeolite catalyst.

Example IV

A steamed (746 ° C) Y zeolite with a silica: alumina molar ratio of 5) 1: 1 was washed with an approximately 3 L 1 molar hydrochloric acid solution (0.74 cm concentrated HCl / g zeolite). The leached product had a silica: alumina molar ratio of 9-8: 1. The pore size distributions for both products (relative pore volume dV / d (log d) as a function of pore diameter) are contrasted in FIG. 7 asked.

8300053

Claims (13)

A process for the selective production of middle distillate hydrocarbons, characterized in that a hydrocarbonaceous feed boiling above 316 ° C is contacted under hydrocracking conditions with a catalyst containing a hydrogenation component and a zeolite with expanded pores, consisting of a faujasite-like zeolite, which is steamed and then freed from alumina, and (b) gains a hydrocarbonaceous effluent, more than about ifO vol · # 'above about 1lf9 ° C and below about 371 ° C - boils. 2. Process according to claim 1, characterized in that a Y zeolite is used as faujasite-like zeolite. Process according to claim 1, characterized in that ultrastable Y zeolite is used as faujasite-like zeolite. 20 if. Process according to claims 1 to 3, characterized in that a faujasite-like zeolite is used, which has a sodium oxide content of less than about 0.5% by weight. 5. Process according to claims 1 to if, characterized in that an expanded pore zeolite is used, which has a cubic cell constant less than about 2. ifif nm and a silica to alumina mole ratio greater than about 10: 1. 6. Process according to claim 5, characterized in that a silica to alumina molar ratio of greater than about 20: 1 is used. Method according to claim. 5 or 6, characterized in that an expanded pore zeolite is used which contains less than about 200 ppm by weight of alkali metal oxide. 8. Process according to claims 1 to 7, characterized in that the faujasite-like alumina zeolite is freed by contacting the faujasite-like zeolite with an acid at a pH of less than about 2. Process according to claims 1 to 8, characterized in that the faujasite-like zeolite is steamed at 8300053 at a temperature above about 538 ° C for more than about 1 hour * 10. Process according to claim 9, characterized in that the steam treatment is carried out while standing. Process according to claims 1 to 10, characterized in that a hydrogenation component is used selected from the group consisting of a nickel, cobalt, molybdenum or tungsten compound or mixtures thereof and the catalyst also a matrix of an inorganic oxide contains. 12. Process according to claim 11, characterized in that aluminum oxide is used as matrix. 13 * Process according to claims 1 to 12, characterized in that the feed is boiled above about 371 ° C, with more than about ifO vol. Of the effluent boiling above about 204 ° C and below about 371 ° C. 14. Process according to claim 13, characterized in that a gas oil is used as feed Method according to claims 1 to 1Z *, characterized in that a hydrocracking stage (c) is also applied to at least a part of the hydrocarbonaceous effluent. *******> _ _ I 8300053