CS245543B1 - Method of oleffins production by means of hydrocarbons' pyrolysis started by inorganic compounds - Google Patents

Abstract

The purpose of the solution is the production of olefins as are ethylene, propylene, 1,3-butadiene, isoprene, cyclopentadiene by pyrolysis of hydrocarbons from natural gas, oil and coal processing in the presence of nitrites and metal nitrates 1 st and 2 nd groups of the periodic table a phosphorous sulphide in an amount of 0.001 to about 2.0% by weight. This way the hydrocarbon feedstock is more valuable to the desired alcohol olefins so far. at the same time Coke formation is suppressed thereby increasing operating cycles. solution can be used in the petroleum industry and petrochemicals.

Description

The invention relates to a process for the production of olefins by pyrolysis of individual hydrocarbons or mixtures thereof initiated by substances of an inorganic nature.

To date, low molecular weight olefins such as ethylene and propylene, along with BTX aromas, are among the basic petrochemicals. Olefins are present in ^one crucially obtained by thermal decomposition of hydrocarbons from natural and refinery gas, oil and coal processing. Pyrolysis of hydrocarbons to olefins takes place under harsh, energy-intensive conditions. Maximum ethylene yields in the case of pyrolysis of straight-run gasoline are achieved at temperatures of about 820 to 830 ° C and residence times below 0.3 seconds. Under these conditions, the optimum ethylene mode is used, but at the same time the process selectivity decreases. This is manifested by a decrease in the formation of, for example, propylene in demand at this time, and an increase in yields of undesirable methane, pyrolysis oil, pitch and coke. Therefore, there is an intensive search for such compounds which are capable of influencing the radical process of thermal decomposition of hydrocarbons in such a way that it is possible to work at lower temperatures. This would improve the kinetic parameters of the process and increase selectivity. The compounds that have been monitored for this include certain nitrogen compounds. Pyrolysis of hydrocarbons in the presence of ammonia is known; amines, nitro-, nitro-compounds (AO ČSSR 190 747); sulfur-nitrogen compounds such as ammonium sulfide, thiourea, nitrothiophenol and thiazine (AO CSR 210 039). Although these nitrogen compounds are characterized by high efficiency, their widespread introduction on an industrial scale is hindered primarily by availability and cost.

The above drawbacks are substantially eliminated by the process of olefin production by pyrolysis of a hydrocarbon feedstock in the presence of water vapor and inorganic compounds at a temperature range of 600 to 1300 ° C for a reaction time of less than 1 second, according to the invention nitrates, metal nitrates of the first and second groups of the periodic table and phosphorus sulphide are added to the feedstock prior to pyrolysis in an amount of 0.001 to 2.0% by weight.

The present invention has made progress in that the nitrate and nitrate metal is more appreciated by the hydrocarbon feed. The rate and selectivity of the conversion will be increased. A further benefit of the invention is to utilize the effect of phosphorus sulphide, which effectively prevents the conversion of the hydrocarbons to the pyrocarbon, so that it is not deposited in the form of coke on the inner surface of the pyrolysis apparatus. This allows drives before ⁷ hours of continuous operation of pyrolysis furnaces and avoiding the complex operations of carbon burning furnace tubes. The accelerating effect of nitrites and nitrates in the pyrolysis of hydrocarbons results from their decomposition into nitric oxide and nitrogen dioxide. Both oxide molecules have an odd number of electrons, so they are paramagnetic. By their attack of the reactant molecules, they allow the formation of hydrocarbon radicals, especially in the initiation phase of the pyrolysis.

Phosphorus sulphide P2S5 decomposes under pyrolysis conditions into reaction intermediates reacting with the internal surface of the reactor to form metal sulfides and phosphides having a passivating effect on coke formation.

The nature and properties of the ingredients determined the manner of dosing into the pyrolysis system. The water-soluble compounds were metered in the form of aqueous solutions and the hydrocarbon-soluble additives were added to the hydrocarbon feed.

The subject matter of the invention is apparent from the examples without departing from the examples.

Example 1

The experiments were carried out in stainless steel flow-through tubular reactors at a temperature range of 600 to 1300 ° C. The pressure ranged from 0.05 to 0.5 MPa, preferably from 0.1 to 0.2 MPa, with a residence time of less than 1 s. Working in the presence of water vapor in an amount of 20 to 300% per hydrocarbon feed. Hydrocarbons and petroleum fractions having a boiling point of 30 to 400 ° C were pyrolyzed, in particular light and heavy naphtha, catalytic reforming gasoline after extraction of aromatics (raffinate), kerosene and gas oils.

The effect of inorganic additives was investigated in the pyrolysis of n-heptane and naphtha. The rate constant from the first order equation was used to determine the initiating effect of the metal nitrites, nitrates, and phosphorus sulfide. The results from the pyrolysis of n-heptane are shown in Table 1 and from the pyrolysis of primary gasoline in Table 2,

TABLE 1

Influence of metal nitrites and nitrates on pyrolysis of n-heptane

Temperature, ° C 700 H2O ratio 3 Dwell time, p 0,074 0,068 0,130 0,052 Additive amount,% wt. 0 1.0 0.92 0.68 additive - NaNO NaNO KNO3 Pyrolysis rate, s' ⁴ 3.47 3.85 3.85 3.92 Selectivity (moles of ethylene / / 100 moles reacted ' n-C7 119.4 144.2 157.4 145.6

TABLE 2

Effect of NaNCu and Mg (NO3) 2 on primary pyrolysis gasoline (b. 34 to 125 ° C) Temperature, ^Cl 780 H 2 O / raw material ratio 0.5 Dwell time, p 0.19 Additive amount,% wt. 0 1.0 0.08 additive - NaNO P2S5 Amount of pyroplyn,% wt. 83 86 84 Yield,% wt. methane 10.1 11.3 10.8 ethylene 22.2 27.4 24.6 propylene 14.1 15.6 13.1

Example 2

The effect of phosphorus sulphide on coke formation was monitored by pyrolysis of gasoline raffinate in a tubular reactor in the absence of water vapor. Pyrolysis of gasoline raffinate alone at 820 ° C for three hours produced 0.83 g of coke. In the pyrolysis of gasoline raffinate, which contained 0.5 wt. P2S5, only 0.12 g of coke was produced over the same period. The result indicates a significant inhibitory effect of phosphorus sulphide on coke formation.

Claims (2)

Processes of olefins by pyrolysis of the hydrocarbon-initiated inorganic compound in the presence of water vapor at the temperature range from 000 to 1300 ^Q C for a reaction time of less than 0.5 seconds, characterized in INVENTION in that 0.001 to 2.0% by weight of nitrates, metal nitrates of the first and second groups of the periodic table and phosphorus sulphide are added to the feedstock prior to pyrolysis.