CS210039B1 - Method of pyrolysis of hydro carbons in presence of admixtures with inhibitory effect on the coke formation - Google Patents

Description

The present invention relates to a process for pyrolysis in the presence of coke-forming additives.

At present, the pyrolysis of the hydrocarbon feedstock is carried out under conditions where the rate and selectivity of the conversion to olefins 1 is relatively low with optimum process control. Undesirable products include methane, pyrolysis oil, pitch and coke. While methane is predominantly produced by primary reactions, heavy liquid pyrolysis fractions, pitches, coke, and carbon oxides are produced as a result of secondary reactions, the course of which is facilitated by a multi-component highly reactive olefin-aromatic system with a significant contribution to the internal surface of the reaction system.

Recently, due to the rapid growth in olefin production, it has gradually shifted away from traditional raw materials such as hurting or healing. are ethane, refinery gases, and straight-run naphthas to heavy gas oil-type petroleum fractions. The pyrolysis of higher petroleum fractions produces substantially more liquid pyrolysis fractions and coke compared to the pyrolysis of gasoline. Therefore, considerable research efforts are increasingly devoted to increasing conversion of feedstock at the expense of liquid products and suppressing coke formation. Solving these problems would lead to a significant improvement in economic indicators.

One possible way to improve the production of lower olefins is to realize a pyrolysis process in the presence of substances that would make it possible to lower the pyrolysis temperature, increase the rate of radial conversion, increase the flexibility of the pyrolysis process, improve selectivity and use feedstocks with different properties. Such compounds (initiators, catalysts, activators, promoters / of both homogeneous and heterogeneous nature) which favorably influence the pyrolysis process in addition to the compounds (inhibitors, retardants, deactivators, passivators) which reduce the formation of undesired pyrolysis products are intensively sought. For this purpose, several types of chemical compounds are studied, and their wider application under operating conditions is most often limited by efficiency, availability or cost.

The above drawbacks are overcome by the pyrolysis of hydrocarbons in the presence of coke-inhibiting additives which consist in the fact that individually hydrocarbons and petroleum fractions boiling at 30 to 400 ° C in the presence of water vapor and coke-inhibiting additives such as mixtures of sulfur and nitrogen in an amount of 0.001 to 1.5% by weight are pyrolyzed, the additives improving selectivity and accelerating the conversion in the temperature range of 600 to 900 ° C.

Of the inorganic compounds, elemental sulfur, hydrogen sulfide, carbon dioxide, sulfur dioxide, sulfides, sulfates, metal thiosulfates of the first and second groups of the peroxygen table, or ammonia are suitable.

Of the organic sulfur substances, compounds of the mercaptan, sulfide, sulfoxide, disulfide, xanthan, thiophene, thiophenol type and their aromatic and aliphatic derivatives, wherein the derivatives contain 1 to 32 carbon atoms. They are furthermore phosphorus compounds and sulfides of the alkenylthiophosphonic acid or O, O-dialkyldithiophosphoric acid type, or their inorganic and organic salts or esters, in particular the metal salts of the first and second groups of the periodic table, the alkyls containing 1 to 16 carbon atoms. Among the compounds having both sulfur and nitrogen molecules, ammonium sulfide, thiourea, dithiocarbamates, thiocyanates and thiocyanates, nitro-thiophenol, thiazine and its aromatic and aliphatic derivatives are suitable, the derivatives having 1 to 20 carbon atoms. Of the inorganic nitrogen compounds, nitrogen oxides, ammonia, and organic substances of aliphatic or aromatic primary, secondary, tertiary-heterocyclic bases, nitro- and nitro-compounds are used, the hydrocarbon radical containing 1 to 20 carbon atoms and the nitrogen complexes formed by said compounds.

The invention has made progress in that by the action of elemental sulfur and sulfur compounds, the conversion of the hydrocarbons to the carbon monoxide is effectively prevented, so that it is not deposited in the form of coke on the inner surface of the pyrolysis apparatus. This makes it possible to prolong the continuous operation of pyrolysis furnaces and to avoid complicated coke firing operations from the furnace tubes. Inhibition of coke formation does not take place at the expense of olefinic extracts; on the contrary, yields of, for example, ethylene increase in many cases. The action of the nitrogen compounds increases the hydrocarbon lure to a greater extent as a result of the increase in the rate and selectivity of the conversion. The synergism of sulfur and nitrogen compounds in the pyrolysis process induces synergism in that some nitrogen compounds act as activators of sulfur compounds.

The nature and properties of the ingredients were determined by the method of dosing into the pyrolysis system. Additives which are normally in a gaseous state (eg hydrogen sulphide) and sa

Table 1 was dosed directly into the reactor. Water-soluble compounds / e.g. sulfides, sulfates were dosed in the form of aqueous solutions, and hydrocarbon-soluble additives were added to the starting material.

The method of pyrolysis of hydrocarbons in the presence of coke-inhibiting additives is described in the following examples, without being limited to these Examples.

The experiments were carried out in stainless steel flow-through tubular reactors at a temperature range of 600 to 900 ° C.

The pressure ranged from 0.05 to 0.5 MPa, preferably from 0.1 to 0.2 MPa, and the residence time was less than 1 s. Water inert was used as an inert diluent. Working in the presence of water vapor in an amount of 20 to 150 percent per hydrocarbon particle. Pyrolyzed are individually hydrocarbons and petroleum fractions boiling from 30 to 400 ° C, in particular light and heavy naphtha, catalytic reforming gasoline after aromatic / raffinate / kerosene extraction and gas oils.

The results of pyrolysis of the primary gasoline of the following composition (group composition in% by weight) in the presence of water vapor are given in Table 1.

Primary gasoline composition:

n-alkanes 37.17 and z-alkanes 44,81 Cyclanes 13.94 aromatics 3.08 density / kg / m ^ / 668 You're welcome. distillation / ° C / 34 end of distillation / ° C / 125 sulfur content / 7 wt. / 0,016

Effect of sulfur and nitrogen additives on composition at 780 ° C, H ₂ O / bi = 0.5 inhibitor Amount of inhibitor 1 2 / 7 wt./ - 0.01 Lifetime / sec / 0.19 0.19 Liquid fraction /% wt / 18.90 16.20 methane 12.08 11.20 ethane 3.02 3.28 ethylene 2 2.30 24,17 propylene 11.62 16.20 butadiene 3.45 3.70 Hydrocarbons C4-C5 + 28.45 25,06 Legend: 1 - no inhibitor , raw material content is e 2 - nitric oxide 3 - Nitrobenzene 4 - aniline 5 - Thiophene δ - mixture 0,1% wt. of thiophene + 0.1 7. wt

nitrobenzene

reaction products. mass./ 3 4 5 6 0,1 + 1 1 0.1 0.1 0.19 0.19 0.16 0,1 4 18.53 16.73 15.44 16.14 10.41 10.16 12.06 9.65 2.46 4.59 4.25 4.46 24.68 25.14 24.75 27.36 14.43 12.88 1 9.96 17.37 4.54 3.16 2.86 3.10 24.76 27.15 20.58 21, 78

0.016 7 with sulfur

Example 2

The inhibitory effect of sulfur compounds on coke suppression was observed in the pyrolysis of gasoline from catalytic reforming after aromatic extraction (gasoline raffinate). The results are shown in Table 2. The experiments were carried out in a tubular reactor without an inert diluent under the following conditions:

Temperature: 820 ° C

Retention time0.95 s

Feed rate: 30.5 gh ^- 1

Experiment time: 1 hour

Petrol raffinate of the following properties / group composition in 7 wt. /:

n-alkanes 25.25 Start of distillation (° C) 27 and z-alkanes 58,10 ' End of distillation (° C) 156 Cyclanes 7.09 Sulfur content (ppm) 7 »1 Aromates of C 1 -C 8 3.67 rest Density / k g / m / 5.89 Results from measured inhibitory effect 6 90 the effects of sulfur additives are given in Table 2,

Table 2

Effect of sulfur additives on coke formation during pyrolysis of petrol raffinate at 820 ° C and residence time of 0.95 s

Sulfur Fracture concentration in the feed / Z hm./ number coke / 8 / 7. mass./ without sulfur compound - .0,81 2.66 t io hair dryer 0.1 0,3 7 1, 22 thiophene 1, 0 0.12 0.39 dibenzylsulf id 0.5 0.20 0.66 d ibenzyl disulfide 0,0-di-n-butyldi thiophosph o- 0.1 0.24 0.78 rečnan Zn 0.5 0.03 0.10 elemental sulfur. 0.05 0.08 0.26 with carbon black 0.05 0.10 0.33 butyl mercaptan 0.5 0.22 0,7 2

SUBJECT

Claims (3)

A process for the pyrolysis of hydrocarbons in the presence of coke-inhibiting additives, characterized in that the individual hydrocarbons and petroleum fractions boiling in the range of 30 to 400 ° C are pyrolyzed at a temperature range of 600 to 900 ° C in the presence of water vapor and additives by effect of coke formation, which are sulfur and nitrogen compounds in an amount of 0.001 to 1.5% by weight, added to the feedstock prior to pyrolysis. 2. The process according to claim 1, wherein the sulfur-containing compounds are elemental sulfur, hydrogen sulfide, carbon disulfide, sulfur dioxide, sulfides, sulfates, metal thiosulfates of the first and second groups of the periodic table, raercaptans, sulfides, sulfoxides, disulfides, thiophene. and their aROVENTION of matic and aliphatic derivatives, wherein the derivatives contain from 1 to 32 carbon atoms, furthermore sulfur and phosphorus compounds of the alkenylthiophosphonic acid type or 0,0- dialkyldithiophosphoric acids or their inorganic and organic salts or esters, in particular the metals of the first and second groups of the periodic table, wherein the alkyls contain 1 to 16 carbon atoms. 3. The method of claim 1, wherein the sulfur and nitrogen containing compounds are sulfur-nitrogen compounds such as ammonium sulfide, thiourea, nitrotxophenol, thiazine and aromatic or aliphatic derivatives thereof, wherein the derivatives contain from 1 to 20 carbon atoms.