CS266261B1 - Method of pitches treatment - Google Patents

Abstract

Method of processing rubber from rubber production 2-mercaptobenzothiazole-based accelerators so that pitch up under norraal or increased pressure, preferably at 5 to 20 MPa, thermally split without access to air or oxygen for 0.2 to 6 h at 200 ° C to 500 ° C and separated from the cleavage products gaseous ones and preferably made them obtain sulfur and / or hydrogen sulfide.

Description

The invention relates to a process for treating organic resinous substances formed in the production of rubber accelerators based on mercaptobenzothiazole by subjecting them to thermal cracking and using the gaseous fraction formed as a source of sulfur and / or hydrogen sulfide.

In the manufacture of rubber accelerators based on mercaptobenzothiazole, in particular in the manufacture of 2-mercaptobenzothiazole itself, 2,2'-dibenzothiazyl disulfide, N (morpholinyl) -2-benzthiazylsulfenamide and others, some raw materials and intermediates are converted to organic pitch condensates, technologically referred to as they are removed from production as unwanted waste and are either incinerated or stored in various ways! at solid waste landfills. The amount of these pitches and other non-volatile wastes is relatively high, up to 35% due to the production of the main products according to the type of accelerator and the method of its production. I contain! a high proportion of organically bound sulfur (up to 30 wt.% and nitrogen (up to 15 wt.%) and their storage or incineration is therefore associated with considerable environmental problems.

In the published professional literature, only a small porosity deals with the problem of resin processing. Some of these substances can be added: to honorary asphalts or after mixing e.g. with polyvinyl chloride used: as a waterproofing compound. However, I am far from describing these methods! all possibilities for processing these substances. The high sulfur content, which is disadvantageous in these processes and in the combustion of smears as such, provides a precondition for their advantageous use as a source of sulfur and / or sulfur compounds.

According to the invention, organic pitch condensates from the production of rubber accelerators based on 2-mercaptobenzothiazole are treated by thermal cleavage under normal or elevated pressure, preferably at 5 to 20 MPa, without the access of air or oxygen for 0.2 to 6 hours. , preferably 0.3 to 3 hours, at a temperature of 200 to 500 ° C, preferably 350 to 450 ° C, gaseous fractions are separated from the cleavage products and preferably sulfur and / or hydrogen sulfide are obtained therefrom.

Thermolabile resins decompose at elevated temperatures! for gaseous products and semi-liquid residue. In addition to carbon dioxide and nitrogen, a part of the sulfur originally bound to the complex organic compound and, in addition, a certain proportion of hydrocarbons, which increase! energy content of the gas. The choice of pyrolysis conditions makes it possible to adjust both the amount and composition of the gas phase and (to some extent) the consistency of the pyrolysis residue. At lower pressures, the residue is semi-solid with solids content, while at higher pressures they predominate! semi-liquid to liquid components up to temperatures around 450 ° C, over which the abbot already prevails! solid bruises in the rest. Temperature riser supports increase! gas phase formation and improves the efficiency of the sulfur-to-gas transition, especially in the form of hydrogen sulphide, to a lesser extent than low molecular weight sulfur compounds.

In pyrolysis at normal pressure, only a small part of the tar passes into gaseous form, a larger part of the products distills during pyrolysis and is obtained as a liquid part. The pyrolysis residue is black and solid, with a brittle consistency.

For these reasons, temperatures between 350 and 450 ° C, pressures of 5 to 20 MPa and a reaction time of 0.3 to 3 hours can be mentioned as optimal operating conditions. Under these conditions, about 50% of the sulfur present in the original resins passes into the gas phase, while the pyrolysis residue is still easy to handle at operating temperatures above 80 ° C.

The obtained pyrolysis gas can be used as a source of sulfur, while the content of hydrocarbons in it (mainly ethane and ethylene) facilitates its processing into sulfur, e.g. by burning in the Claus furnace. However, it is possible to obtain sulfur or hydrogen sulfide from it by any of the known methods, e.g. absorption, adsorption, etc.

The advantages of the process according to the invention are illustrated in the accompanying examples. They consist, on the one hand, in a substantial reduction in the amount of waste resins by converting a substantial part of them into a recoverable gaseous form, and, on the other hand, in an ecologically significant reduction in the sulfur content of the pyrolysis residue;

CS 266 261 B1 in its conversion into the gas phase, from where it can be technologically and economically isolated in various ways in a suitable form. The pyrolysis residue is solid at temperatures below 80 ° C, practically odorless and can be easily used for the same purposes as originally pitches by prepyrolysis. *

Example 1

By pyrolysis of pitches containing C 48.8 wt. %, H 6.0 wt. 8, N 11.3 wt. % and S 19.9 wt. 8 in an inert nitrogen medium at 280 ° C for 0.5 hours was formed at a pressure of 7.0 MPa

18.5 wt. % of gaseous products. The pyrolysis residue was a dark to black product which was liquid at a temperature above 80 ° C. The gaseous product contained 8.0 wt. % of sulfur compounds, mainly H2S, 9.0% of organic sulfur compounds, mainly ethane and ethylene, and the remainder were inertes, ie CO2, N ₂ and O2- From the flood pit, 7.5% of sulfur passes into the gaseous product, and

9.7% C and H in the form of C _n H _n - '

Example 2 '.

Pyrolysis of smdl of the same composition in an inert nitrogen medium for one hour at a temperature of 450 DEG C. and a pressure of 15.3 MPa gave 50.8 wt. % of gaseous product. The pyrolysis residue was black and liquid at a temperature above 85 ° C. It was 29.2 wt. % of organic sulfur compounds, mainly H ₂ S, 25.5 wt. 8 organic non-sulfur substances and the remainder of the inert, ie CO 2, N 2, O 2 and CO. 65.6% S was converted from the original smdl to gaseous products. The remainder contained 14.0 wt. % WITH.

Example 3

Pyrolysis of resins of the same composition in an inert, nitrogen medium at 400 DEG C. for 1 hour at atmospheric pressure gave 20.0 wt. % of gaseous product, 61.8 wt. % of liquid product distilled off during pyrolysis and 18.2 wt. % of pyrolysis residue. The pyrolysis gas contained 24.9 wt. % of organic sulfur compounds, mainly H2S, 12.3 wt. % of organic sulfur compounds and the remainder of the inert, t. j. COj, Nj, O2 and CO. The product distilled off during pyrolysis contained 8.5 wt. % S. The pyrolysis residue was black, brittle in nature, which did not melt even at temperatures above 350 ° C. In the gaseous product there was 24.1% and in the liquid product 38.2 8 of sulfur from the original sulfur content in the pitch.

Claims (1)

Process for processing resins from the production of rubber accelerators based on 2-mercaptobenzothiazole, characterized in that the resins are thermally cleaved at normal or elevated pressure, preferably at 5 to 20 MPa, without access of air or oxygen for 0.2 to 6 hours, preferably 0.3 to 3 hours, at a temperature of 200 to 500 ° C, preferably 350 to 450 ° C, gaseous fractions which are a source of sulfur and / or hydrogen sulfide are separated from the cleavage products.