JPS6255897B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a process for catalytic cracking of hydrocarbon oils in the presence of a cracking catalyst comprising at least one crystalline zeolite. The abovementioned catalysts are used on a large scale in industrial crackers for the production of motor gasoline or their components. Crystalline zeolite-containing catalysts differ from amorphous conventional cracking catalysts made of alumina and silica by their higher activity and selectivity. However, the disadvantage is that crystalline zeolites are more or less susceptible to contamination with heavy metals such as cobalt, molybdenum, tungsten, copper, vanadium, nickel and especially iron. In particular, the last three metals are found in certain crude oils and certain crude oil fractions that are to be catalytically cracked. Although methods for removing the above heavy metals from crude oils or fractions thereof are known, it is still desirable to explore means of avoiding the need for such removal prior to performing the desired conversion of hydrocarbon oils. It is. During the catalytic cracking of hydrocarbon oils, the polluting effects of heavy metals manifest themselves in a gradual decrease in the activity and selectivity of the catalyst and an increase in the formation of coke and undesirable by-products. Deterioration of the desired properties occurs with progressively increasing heavy metal content of the cracking catalyst. According to the present invention, the undesirable effects of heavy metals on the decomposition catalyst can be reduced or suppressed by adding a small amount of boron to the catalyst. The present invention therefore provides a catalyst comprising at least one crystalline zeolite and contaminated with at least one heavy metal, especially iron, selected from the group of nickel, vanadium and iron, the heavy metal being between 0.1 and
A process for catalytic cracking of hydrocarbon oils in the presence of a catalyst present in a total amount of 2.0% by weight, said catalyst also containing 0.01-2.5% by weight of boron. The catalytic cracking process is preferably carried out at temperatures in the range 400°C to 650°C and pressures in the range from reduced pressure to several hundred bar. Fixed bed, fluidized catalyst, suspended solid or riser types of operation are applicable. No hydrogen is added and individual conditions vary depending on the feedstock and desired product characteristics. The feedstock oil charged to the cracking operation is a hydrocarbon oil obtained from petroleum, shale oil and/or tar sand, and has an initial boiling point higher than the final boiling point of gasoline. Suitable raw materials are, for example, gas oils, fuel oils, deasphalted oils, waxes and residual oils. The present invention uses a catalyst composed of naturally occurring or synthetic crystalline aluminosilicates or zeolites. The zeolite component of the catalyst is preferably ion-exchanged with non-toxic metal ions, such as rare earth metal ions, which improves the activity of the catalyst. Boron can be added to the catalyst before as well as during the decomposition reaction by known methods such as ion exchange, dry blending, impregnation or precipitation. The above additions are very preferably
A solution of a volatile boron compound or an organic or inorganic boron compound in water or an organic solvent is added to the gas used to regenerate the catalyst, to the hydrocarbon feed or recycle oil, or before regeneration. This is done by adding to the steam used to remove the catalyst. The treatment agent used in the method of the invention is a compound of boron. It can be organic or inorganic. A suitable treating agent is boron oxide or is capable of being converted to boron oxide upon calcination of the catalyst containing the treating agent. Examples of processing agents include orthoboric acid, tetraboric acid, boron pentasulfide,
Boron trichloride, ammonium diborate, calcium borate, diborane, magnesium borate, methyl borate, butyl borate, tricyclohexyl borate, 2,6-ditert-butylphenyl dibutyl borate, cyclohexylboronic acid, mono ethyl dodecylic acid boronate and mixtures thereof. Treatment agents containing significant proportions of sodium, such as sodium tetraborate, or other known decomposition catalyst poisons, are less preferred. Suitable organoboron compounds are alcohol esters of boric acid such as tri-n-pentylborate. It can be dissolved or decomposed in a suitable carrier, such as xylene, and added to the hydrocarbon oil feed to the cracking process and contacted with the catalyst under cracking conditions. Alternatively, a boron-containing treatment agent, such as boric acid in aqueous solution, may be introduced into the regeneration reaction zone along with the conventionally used stripping steam. When using an impregnation method, the boron-containing treatment agent can be dissolved in either an aqueous or non-aqueous solution. For example, an aqueous solution of ammonium diborate may be used, or if a non-aqueous solvent is desired, a xylene solution of an arylborate compound such as 2,6-di-tert-butylphenylborate may be used. good. The normal operation of the cracking process is not affected by the presence of boron in the catalyst, so for cracking and regeneration temperatures, hydrocarbon charge rate, charge/recirculated oil ratio and other parameters. It is possible to choose a customary value. The catalyst is expressed as a percentage by weight based on the weight of fresh catalyst.
Preferably it contains 0.1-1.5% by weight boron. The amount of heavy metals, especially iron, in the contaminants is usually calculated as the total amount of metals based on the weight of fresh catalyst, and is 0.1
Varies within the range of ~2.0% by weight. Next, in order to explain the present invention more specifically,
Examples are shown below. Example 1 A series of cracking experiments were carried out in the presence of a fractionating catalyst containing Houjasite-Y under the following conditions. Pressure 1 bar Reaction temperature 485℃ Regeneration temperature 600℃ Feed oil Distilled oil from Kuwait Space velocity 6.4Kg/Kgh Relational selectivity of conversion during cracking operation (S _R )
is the following formula: S _R = P _B /P _C (where P _B = total weight of the product fraction C ₅ -221°C expressed as a percentage of the feed oil, and P _C = the total weight of the product fraction expressed as a percentage of the feed oil) is the total weight of coke expressed as a percentage. Some amount of iron naphthenate (0.65% iron by weight) is added to the catalyst by impregnation. Furthermore, the amount of passivating boron indicated in the table is added by impregnation using an inorganic salt solution. The table shows measured values which show that the addition of boron to iron-containing catalysts has a favorable effect on the production of gasoline, an adverse effect on the formation of coke and therefore a favorable effect on the relative selectivity. It is shown that.

EXAMPLE 2 Catalyst 1 and Catalyst 2 were equilibrium catalysts obtained from commercial cracking operations using feedstocks derived from mid-continental US source oils. Each catalyst is treated with a boron treatment agent, and each treated catalyst is
Numbered 1A and 2A. The metal and boron concentrations on the catalyst at the beginning of each run were as follows.

[Table] Boron was added to catalyst 1A by impregnating 50 g of the catalyst with a solution of 5.44 g of tripentyl borate in 15 ml of toluene. Following boron impregnation treatment,
The catalyst was dried in the presence of nitrogen (to prevent deleterious oxidation of the toluene) until the temperature rose to 482°C and then calcined in air at about 482°C. Catalyst 2A
For 25g of catalyst, add 0.74g of boric acid to water.
The boron was added by impregnation with an aqueous solution dissolved in 7.5 ml, then dried in nitrogen at 482°C for 1 hour, and then calcined in air at a temperature of about 482°C for 1 hour to add boron. It was done. The catalyst was tested in a fixed bed catalytic cracker under the conditions shown in the following table. Charge oil preheating temperature: 480°C Catalyst temperature: 480°C Catalyst/oil ratio: 2.5/1-7/1 The gas oil feed oil used had the following properties. Density (Kg/m ³ ) 894 Sulfur (wt%) 0.8 Saturated compounds (wt%) 56.88 Monoaromatics (wt%) 18.94 Diaromatics (wt%) 17.04 Triaromatics (wt%) 6.04 Tetra-aromatics (wt%) %) 0.10 Basic nitrogen (wt%) 0.20 The charging rate is 70 wt% or 75 wt% as shown below.
Conversion was varied to provide at least three conversion levels to allow for interpolation of catalyst performance values.

[Table] From the above results, it is clear that when the catalytic cracking process of the present invention was implemented, the gasoline yield increased and the coke yield decreased quite significantly. Example 3 A sample of contaminated catalyst 1 was impregnated with an aqueous solution of boric acid to obtain the same level of added boron as catalyst 1A. Boron-containing catalyst in the presence of nitrogen at temperature
Dry to 482°C. Half of dry catalyst (catalyst 3)
was tested to determine its decomposition performance. The other half of the dried catalyst (catalyst 4) was calcined in air at 482° C. for 1 hour to fix the boron on the catalyst. The test results of the catalyst are summarized as follows.

[Table] From the above results, it is clear that the calcination environment has no significant effect on the performance of the contaminated catalyst impregnated with boric acid. A similar study using a catalyst impregnated with organoboron (tripentyl borate) showed slightly higher activity relative to the air-calcined catalyst. Within the experimental inaccuracy of the test,
It is noteworthy that Catalyst 3 and Catalyst 4 exhibited similar catalytic performance to Catalyst 1A, indicating that organoboron compounds and boric acid are necessarily equivalent in their potency against immobility due to metal contamination. Worth it.

Claims (1)

[Claims] 1. Contains at least one type of crystalline zeolite,
In the catalytic cracking process of hydrocarbon oils in the presence of a catalyst contaminated with small amounts of at least one heavy metal selected from the group of nickel, vanadium and iron, the heavy metals are present in a total amount of 0.1-2.0% by weight. and the catalyst further contains 0.01 to 2.5% by weight of boron. 2. Process according to claim 1, characterized in that the catalyst contains 0.1 to 1.5% by weight of boron. 3. The method according to claim 1 or 2, characterized in that the heavy metal is iron. 4. Process according to claim 3, characterized in that the heavy metals are present in a total amount in the range 0.1-2.0% by weight. 5 When used for catalytic cracking of hydrocarbon oil, it contains at least one type of crystalline zeolite, including nickel,
The catalyst is contaminated with a small amount of at least one heavy metal selected from the group of vanadium and iron, wherein the heavy metal is present in a total amount of 0.1 to 2.0% by weight, and the catalyst further contains 0.01 to 2.5% by weight of boron.
The above-mentioned catalyst characterized in that it contains. 6. The catalyst according to claim 5, characterized in that the catalyst contains 0.1 to 1.5% by weight of boron.