JPH08176561A - Hydro isomerization method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress the formation of methane without affecting LPG and light liquid yields by reacting a +5C paraffin-containing feedstock in the presence of hydrogen, carbon dioxide and a specific catalyst under specific reaction conditions to efficiently conduct hydroisomerization.

SOLUTION: For example, under the hydroisomerization reaction conditions of a temperature of 320-385°C, a hydrogen pressure of 750-1,500 psi and a space velocity of 0.1-10.0 LHSV(liquid hourly space velocity), a +5C paraffin- containing feedstock is reacted in the presence of hydrogen, carbon dioxide and a VIII non-noble metal or VI metal catalyst or both supported on alumina or alumina-silica to conduct hydroisomerizataion in a suppressed 1C yield without substantial effect on other light gas yields.

COPYRIGHT: (C)1996,JPO

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a C ₂ -C ₄ yield which is substantially minimized when the reaction is carried out in the presence of carbon dioxide and the end decomposition, ie the formation of methane, is substantially minimized. The present invention relates to a hydroisomerization method including hydrocracking which exerts no significant effect.

[0002]

BACKGROUND OF THE INVENTION Hydroisomerization processes and catalysts therefor are well known and include noble metals; Pt, Pd, Rh supported on fluorinated alumina; and on silica, alumina or silica-alumina. Included are non-noble Group VIII metals with or without one or more Group VI metals supported. These catalysts are usually bifunctional and contain a metal hydrogenation catalyst and an acid decomposition functional group.

Carbon oxide, carbon dioxide and especially carbon monoxide are disclosed in US Pat. No. 3,711,399 as inhibitors of hydrocracking in isomerization processes using highly acidic fluorine-containing catalysts. Is added in relatively small amounts. Hydrocracking is virtually completely suppressed and C ₄ -yield is virtually negligible.

[0004]

Nevertheless, the yield of LPG and light liquid in the isomerization process is desirable to ensure proper pour points for diesel and jet fuels and the like. For example, methane itself is a particularly undesirable product because the isomerized product is made from Fischer-Tropsch wax which, conversely, is ultimately obtained from methane by syngas production. Finally, there is a desire for an isomerization process that suppresses or substantially eliminates methane production without substantially affecting the yield of LPG and light liquids.

[0005]

In accordance with the present invention, the presence of a catalyst comprising one or more non-noble Group VIII metals or one or more Group VI metals or both metals supported on an acidic support comprising alumina or silica-alumina. By carrying out the hydroisomerization process with the incorporation of carbon dioxide in the reaction mixture below, the terminal decomposition of C ₅ + hydrocarbons is substantially suppressed, for example below about 1.0% by weight of the feedstock.

As a result of the present invention, the yields of LPG and light liquid are substantially unaffected and the yield of methane due to end-cracking is substantially suppressed. It is also reported in the above-mentioned publication that not only the decomposition of the terminal bond but also the decomposition of the disubstituted bond, which has a higher activity rate of decomposition than the terminal bond, can be suppressed. Therefore, the present invention provides a mechanism to suppress hydrogen decomposition much more selectively than the comprehensive operation of the above-mentioned publications. Moreover, the publications use very small amounts of carbon oxide with highly acidic catalysts. The method of the present invention takes a clearly counter-intuitive way to increase the amount of carbon dioxide used (since carbon monoxide is useless) and to further reduce the amount of acidic catalyst. In practicing the present invention, yields of LPG, such as C ₂ -C ₄ and light liquids, such as C ₅ -320 ° F (160 ° C), 320-500 ° F (160-2).
60 ° C.) is not affected, but the yield of C ₁ is kept below about 1% by weight, preferably below about 0.5% by weight.

The amount of carbon dioxide used in combination with the feedstock is at least about 0.2 mol% of the feedstock, preferably at least about 0.3 mol%, preferably about 0.3 mol% to about 1.
It is 0 mol%. While carbon oxides often clump as catalyst poisons, the fact that carbon dioxide alone suppresses end destruction with the non-precious metal functional catalysts of the present invention, and carbon monoxide has virtually no effect on the process, is interesting. The total conversion of feedstocks in the process is 20-90%, preferably 30-70%, more preferably 40-60%.

[0008]

DETAILED DESCRIPTION OF THE INVENTION The active hydroisomerized metal is a non-noble metal selected from Group VIII of the Periodic Table of the Elements. Preferred metals include nickel, cobalt or mixtures thereof, and mixtures thereof with molybdenum of Group VI metals. The Group VIII metal may be present on the catalyst in an amount sufficient to provide catalytic activation of hydroisomerization. Specifically, about 0.05 to about 20% by weight, preferably about 0.1 to 1
A metal concentration in the range 0% by weight, more preferably 2.0 to 5.0% by weight is used. For example, the preferred catalyst has a cobalt loading of 1-4 wt% and a nickel loading of 0.1-1.5 wt%. A Group VI metal, such as molybdenum, may also be used, but the amount may be more, less than or the same as the non-noble Group VIII metal, for example 1.0-20% by weight based on the total weight of the catalyst. , Preferably 8-15% by weight.

The metal is impregnated or added onto the support as suitable metal salts or acids, for example nickel nitrate or cobalt nitrate. The catalyst is then dried and calcined by known methods.

The base silica and alumina used in the present invention are, for example, alkali metal silicates (preferably,
Na ₂ O: SiO ₂ (ranging from 1: 2 to 1: 4), soluble compounds containing silicon such as tetraalkoxysilane, orthosilicate ester; sulfates, nitrates of aluminum alkali metal aluminates, Or chlorides, or inorganic or organic salts of alcosides. When precipitating silica or alumina hydrate from such a starting material solution, a suitable acid or base is added to set the pH value within the range of about 6.0-11.0. Precipitation and aging are carried out with heating by adding an acid or a base under reflux in order to prevent evaporation of the treatment liquid and a change in pH. The remaining steps of the carrier formation process are the same as commonly used, including filtration, drying, calcination, etc. of the carrier material. The carrier may also contain minor amounts, eg, 1-30% by weight, of materials such as magnesia, titania, zirconia, hafnia or the like.

Preferred carriers are less than about 35% by weight silica, preferably about 2-35% by weight silica, more preferably
An amorphous silica-alumina support containing 5-30% by weight of silica and having the following pore structure characteristics:

[Table 1] Pore radius (A) Pore volume 0-300> 0.03 ml / g 100-75,000 <0.35 ml / g 0-30 0-300 Less than 25% of the volume of pores with radius Less than 40% of the capacity of pores with a radius of 100-300 0-300 A

[0012] Such materials and their manufacture are described in US Pat.
It is more fully described in 843,509. Such materials have a surface area in the range of about 180-400 m ² / g, preferably in the range 230-375 m ² / g, in the range 0.3-1.0 ml / g, preferably 0.5-
It has a pore volume in the range of 0.95 ml / g, a bulk density in the range of about 0.5-1.0 g / ml and a lateral compressive strength in the range of about 0.8-3.5 kg / mm.

The feedstock to be isomerized with the catalyst of the present invention is a waxy feedstock, ie C ₅ +, preferably about 350 ° F.
It is obtained from the Fischer-Tropsch process which boils above (177 ° C), preferably above about 550 ° F (288 ° C) and produces substantially conventional paraffins, or from slack wax. Slack waxes include diluents such as propane or ketones (eg, methyl ethyl ketone, methyl isobutyl ketone) or other diluents used to promote the growth of wax crystals which are lubricated by filtration or other suitable means. It is a by-product of the dewaxing operation removed from the oil base stock. Slack waxes are generally paraffinic in nature and have a temperature of about 600 ° F (316 ° C) or higher, preferably 600 ° F or higher.
Boiling in the range of ° F (316 ° C) to about 1050 ° F (566 ° C), 1-
It may contain 35% by weight of oil. Waxes with a low oil content, eg 5-20% by weight, are preferred. But 5-45%
Wax-containing distillates or raffinates containing the waxes of are also used as feedstock. Polynuclear aromatic and heteroatom compounds are typically removed from slack wax by techniques well known in the art, such as the mild hydrorefining process described in US Pat. No. 4,900,707. This method also reduces the sulfur value to preferably less than 5 ppm and the nitrogen value to less than 2 ppm. Fischer-Tropsch wax is a preferred feedstock containing minor amounts of aromatics, sulfur compounds and nitrogen compounds.

The isomerization conditions are as follows: temperature 300-400 ° C, 500-30
00 psig hydrogen, 1000-10000 SCF / bbl hydrogen treatment, space velocity 0.1-10.0 LHSV (liquid hourly space velocity). Preferred conditions are temperature 320-385 ° C, hydrogen at 750-1500 psig, 0.5-2 v /
v / hr.

The catalyst generally used is in the form of fine particles, for example, a cylindrical extrudate, three-lobed pieces, four-lobed pieces, etc., having a size of about 1-5 mm. Hydroisomerization is performed in a fixed bed reactor and the product is recovered by distillation.

[0016]

The following examples serve to illustrate the invention without limiting it. All hydroisomerization studies were conducted in a small up-flow pilot plant. Catalyst is 750 psig, 0.50 LHSV, 690-700 ° F (366
-377 ° C), evaluated at a nominal H ₂ treatment rate of 2500 SCF / B. A 10 cc charge of ground and sized 14/35 mesh catalyst was used in each case. The catalyst is
Silica-Alumina C with 20-30 wt% bulk silica
o 15.2 wt% MoO ₃ and 3.2 wt% CoO were present on the gel. The remainder was collected at intervals of approximately 24-72 hours. The reaction temperature was set to meet the goal of 50% 700 ° F + wax conversion and was not adjusted during the experiment. Fisher used in these studies
The nominal composition of Tropsch wax is 0.70% IBP-5.
00 ° F (260 ° C), 20.48% 500-700 ° F (260-371 ° F), 7
Consisting of 8.82% 700 ° F + (371 ° C). The length of a typical experiment was 800-1000 hours. Boiling point range distributions for gases, naphtha, distillate range products, and lubricating oils were obtained by combining simulated gas chromatography distillation and gas chromatography mass spectroscopy.

The effect of carbon monoxide was evaluated and the catalyst was activated using the following method: 1. Pressure test at about 750 psi hydrogen pressure at 100 ° F (38 ° C). 2. The reactor temperature was raised to 700 ° F (371 ° C) while maintaining the hydrogen pressure at 750 psi and the flow rate at 2500 SCF / bbl. 3. Reactor temperature 700 ° F (371 ° C) for approximately 18 hours
Held. 4. The hydrogen feedstock and pressure were adjusted to standard operating conditions, the feedstock was fed and the operation started.

After feeding the feed, the balance was regularly collected for 16 days to see if the catalyst reached steady state conditions. At this point, the gas was converted from pure hydrogen to 0.405 mol%
The mixture was switched to a mixture of carbon monoxide and the balance hydrogen. After 13 days with a CO / H ₂ mixture, the gas was switched to pure hydrogen to complete the later experiments. In this case C
_{The 1} (methane) increased, likely due to CO hydrogenation under the reaction conditions.

The effect of carbon dioxide was also studied. In this case, a somewhat different but similar catalyst activation method was used, which is shown below. This activation method results in a high yield of methane. 1. The reactor temperature was 250 ° F (121 ° C) at atmospheric pressure under nitrogen.
° C). 2. While maintaining the reactor temperature at 250 ° F (121 ° C),
After performing the pressure test with nitrogen, the pressure test was performed with hydrogen. 3. Reactor pressure 1250 psia with hydrogen flow rate 3400 SCF / B
Raised to. The reactor temperature was raised to 700 ° F (371 ° C) at a rate of 30 ° F (16 ° C) per hour. Once the reactor temperature reaches 700 ° F (371 ° C), hold for about 4-5 hours. 4. Heat the pressure test with hydrogen; reduce the hydrogen supply and pressure and return to standard operating conditions; feed the raw materials and start the operation.

As in the previous experiment, once the feed has been fed in, the rest is regularly collected for 13.5 days to ensure that the catalyst has reached a stable state. At this point, the gas was switched from pure hydrogen to a mixture of 0.604 mol% carbon dioxide and the rest of the hydrogen for the rest of the experiment.

The effect of carbon monoxide on the performance of the catalyst is shown graphically in FIGS. In these figures, the first vertical dotted line shows CO introduced at about 320 hours and the second vertical dotted line shows CO discharged at about 650 hours.
In general, CO appeared to have little effect on catalyst performance. The most significant effect is the reduction in 700 ° F + (371 ° C +) wax conversion observed almost immediately after this CO was introduced. This decrease continued until the conversion leveled at about 55% and remained at this level even when pure hydrogen was reintroduced into the system.

A slight change in methane yield was also detected.
The yield of methane actually increased when CO was introduced. This happened even when the conversion level was decreasing. In general, methane yield is reasonably linked with conversion (ie, increasing conversion usually increases methane). However, in this case, especially the level of methane is significantly reduced when pure hydrogen is reintroduced, and almost exactly as much as the amount of methane that would be produced if CO was quantitatively converted to methane. In agreement, the slight increase in methane yield may be due to CO hydrogenation.

The remaining products (eg C ₂ -C ₄ , C ₅ -320 ° F)
(160 ° C), 320-500 ° F (160-260 ° C), 500-700 ° F (26
0-371 ° C) showed little or no effect of CO other than the differences due to changes in conversion. The effect of carbon dioxide on the performance of the catalyst is shown in the graphs of Figures 7-12. The vertical dotted line in these figures is the C that was introduced in about 320 hours.
Indicates O ₂ . Although the selectivity of the product for this experiment is significantly different from that obtained in the CO experiment (the first reason being the different method of activation), the first important thing is that CO
_{It is} a relative effect of ₂ .

Immediately after the introduction of the CO ₂ / H ₂ mixture, 700 ° F + (3
Wax conversion decreased by about 17%. After that, the conversion slowly started to increase but did not reach the original level.

Methane yields show the most dramatic changes as a result of CO ₂ . The activation method used in this experiment gave a very high yield of methane of about 2% by weight.
The introduction of CO ₂ reduced this level to less than 0.30% by weight, but remained that way for the duration of the experiment. The slight decrease in methane yield is expected to be due to the decrease in conversion. However, the effect is too great to explain the overall reduction.

The remaining products (eg C ₂ -C ₄ , C ₅ -320 °
F (160 ° C), 320-500 ° F (160-260 ° C), 500-700 ° F (2
(60-371 ° C), little or no effect of CO ₂ was observed other than the difference due to the change in conversion.

The table below shows the actual product yields of the CO ₂ experiment.

[Table 2] Total time (hours) 297.0 320.5 434.0 650.0 770.5 Elapsed time ---- t = 0 t = 113.5 t = 329.5 t = 450 700 ° F + conversion 46.88 52.12 41.64 40.67 45.71 CH ₄ 2.005 2.022 0.265 0.256 0.237 C ₂ H ₆ 0.196 0.190 0.033 0.037 0.043 C ₃ H ₈ 0.416 0.414 0.358 0.408 0.472 C ₄ H ₁₀ 1.140 1.182 1.054 1.289 1.555 t = 0 is the time when carbon dioxide was added.

The above data was taken after a steady state was reached. C ₁ (methane) is virtually suppressed; C ₂ is somewhat suppressed; C ₃ and C ₄ are virtually unaffected, so C ₂ -C ₄ is virtually unaffected after all It can be clearly seen from this table. Moreover, the total conversion was suppressed at the beginning of the CO ₂ addition and recovered somewhat as the reaction proceeded. Therefore, the decomposed product of C ₂ -C ₄ is about 1
It ranges from wt% to about 3 wt%.

[Brief description of drawings]

FIG. 1 is a graph showing the conversion of 700 ° F + (371 ° C +) wax conversion and time obtained when carbon monoxide is added to the feedstock.

FIG. 2 is a graph showing the relationship between methane yield and time in the same case.

FIG. 3 is a graph showing the relationship between C ₂ -C ₄ yield and time in the same case.

FIG. 4 is a graph showing the relationship between the yield of C ₅ -320 ° F (160 ° C) and time in the same case.

FIG. 5 is a graph showing the relationship between 320-500 ° F. (160-260 ° C.) yield and time in the same case.

FIG. 6 is a graph showing the relationship between 500-700 ° F. (260-371 ° C.) yield and time in the same case.

FIG. 7 is a graph showing the relationship between 700 ° F + (371 ° C +) wax conversion and time obtained when carbon dioxide is added to the feedstock.

FIG. 8 is a graph showing the relationship between methane yield and time in the same case.

FIG. 9 is a graph showing the relationship between C ₂ -C ₄ yield and time in the same case.

FIG. 10 is a graph showing the relationship between the yield of C ₅ -320 ° F (160 ° C) and time in the same case.

FIG. 11 is a graph showing the relationship between 320-500 ° F. (160-260 ° C.) yield and time in the same case.

FIG. 12 is a graph showing the relationship between 500-700 ° F. (260-371 ° C.) yield and time in the same case.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location C10G 45/64 9547-4H 49/04 9547-4H 49/08 9547-4H // C07B 61/00 300 (72) Inventor Robert J. Bittenblink Shady Glenn Drive 836, Baton Rouge, Louisiana, USA 70816

Claims (1)

[Claims] 1. Under hydroisomerization reaction conditions, a C ₅ + paraffin-containing feedstock is loaded with hydrogen, carbon dioxide and a non-noble Group VIII metal or Group VI metal or both on alumina or silica-alumina. The method of hydroisomerization, wherein the yield of C ₁ is suppressed and the yield of other light gases is not substantially affected, which is characterized by reacting in the presence of a catalyst comprising