«P-DCB-1»: Synthesis of paradichlorobenzene
TECHNOLOGY OF THE SYNTHESIS OF PARADICHOLOROBENZENE
Paradichlorobenzene (p-DCB) is a valuable product of industrial organochlorine synthesis, is used as a deodorant, insecticide, antiseptic, lacquer solvent, preservative in the leather industry, is a raw material for the production of intermediates, dyes and pharmaceuticals.
Recently, there has been an increase in the demand for p-DCB, which is associated with its use as a raw material for the production of highly structural thermoplastics – polyphenyl sulfides (PPS).
In the US, more than 50% of p-DCB produced is used to produce PFC. Part of the need for p-DCB is covered by its isolation from the bottoms of chlorobenzene (CB) production. However, this applies only to countries with significant CB capacities. In other cases, it becomes necessary to create special production facilities for p-DCB.
The essence of the process:
Paradichlorobenzene is obtained by chlorination of benzene or monochlorobenzene in the temperature range of 55÷60°C using a NaY type zeolite catalyst.
Schematic diagram of pilot production of paradichlorobenzene:D-1 – drum of chlorobenzene; P-2 – chlorobenzene dosing pump; A-3/1 – adsorber for drying chlorine; A-3/2 – adsorber for drying chlorobenzene; R-4 – chlorination reactor; F-5/1 – filter; F-5/2 – filtrate capacity; D-6 – absorption capacity; E-7 – vat boiler; C-8 – distillation column; E-9 – capacitor; D-10 – distillate drum; D-11 – circulation drum; P-12 – circulation pump; E-13 – air cooler
Advantages:High selectivity of the process (78%) with complete conversion of monochlorobenzene.Possibility of separating p-DCB from a mixture of its isomers.
DEMERUS: Mercaptan removal technologies
(Demerus) was developed by the Scientific and Technical Center «AhmadullinS» in the 90s of the XX century to solve multifaceted problems of mercaptan removal – demercaptanization of natural gas, liquefied hydrocarbon gases, gasoline, kerosene and diesel fractions, gas condensates and light oils. A feature of the proposed technology is the use of a heterogeneous polymer-based phthalocyanine catalyst.Demercaptanization is the process of removing mercaptans (mercaptan sulfur) from hydrocarbon fractions. For the purification of liquefied hydrocarbon gases (LHG) from mercaptans, alkaline extractive demercaptanization is mainly used, followed by catalytic alkali regeneration. In this case, along with the removal of mercaptans, desulfurization of LPG is carried out.
For the kerosene fraction, the process can be alkaline, but in this case it proceeds directly in a hydrocarbon medium in the presence of a phthalocyanine catalyst, air oxygen and alkali. Removal of mercaptans occurs due to the oxidation of corrosive mercaptans present in kerosene to inert disulfides:
2RSH + 0,5 O2 → RSSR + H2O
Catalytic oxidative demercaptanization is a deodorization process, i. odor removal without changing the total sulfur content in the fraction.
To purify kerosene from mercaptans, a hydrotreatment process is often used, while sulfur compounds, including mercaptans, at high temperature, in the presence of a nickel-molybdenum catalyst and hydrogen, are converted into hydrogen sulfide and sent to the Klaus plant for the oxidation of hydrogen sulfide to elemental sulfur. In the process of hydrotreating kerosene, demercaptanization is accompanied by the removal of sulfur compounds. Purification of gas condensates and light oils is mainly carried out according to the technology of alkaline purification of LPG. The main goal in this case is the removal of corrosive methyl and ethyl mercaptans to prepare gas condensates and light oils for transportation.
Removal of mercaptans – purification of natural (DEMERUS NG process) and liquefied (DEMERUS LPG process) hydrocarbon gases is carried out by extraction with an alkaline solution of mercaptans contained in the raw material to be purified, followed by alkali regeneration in the presence of a heterogeneous KSM catalyst. If carbonyl sulfide (COS) is present in the raw material, the demercaptanization unit is preceded by a regenerative diethanolamine purification unit from COS (DEMERUS LPG+COS technology).
The demercaptanization of the gasoline fraction (DEMERUS NAPHTHA process) is carried out by the method of alkaline oxidative demercaptanization in the presence of a heterogeneous KSM catalyst.
The technology for removing mercaptans from the kerosene fraction (the DEMERUS JET process), used to produce top quality aviation kerosene and white spirit deodorization, is based on alkaline oxidative demercaptanization.
Purification of gas condensates (DEMERUS GASCOND process), used exclusively for their preparation for transportation, is based on extractive alkaline purification of mercaptans with the release of disulfide oil.
Of the methods for cleaning gases from COS, the most common are its extraction with an aqueous solution of diethanolamine (DEA), followed by the regeneration of DEA, saturated with COS hydrolysis products, at 120-130 ° C (DeCOS-2 technology), as well as COS hydrolysis with a hot alkali solution, flowing at a temperature of 80°C.
DeCOS-1 technology. is aimed at purifying light hydrocarbon feedstock, in particular PPF, from carbonyl sulfide by its hydrolysis in hydrocarbons by reaction with an alkaline reagent (promoter) containing water-soluble polar organic compounds, followed by separation and regeneration of an alkaline reagent saturated with sulfur compounds by air treatment in the presence of a heterogeneous catalyst KSM- X. The main advantages of the proposed method are the availability of polar water-soluble organic compounds contained in the alkaline reagent, their high efficiency in the decomposition of carbonyl sulfide and insolubility in hydrocarbons, which allows the process of decomposition of carbonyl sulfide in the purified light hydrocarbon feedstock at temperatures of 30÷40°C and eliminates the need for its subsequent water flushing.
LOCOS: Wastewater treatment
The LOCOS technology (LOCOS) was developed for the neutralization of industrial wastewater and formation water from toxic inorganic sulfides (NaHS, Na2S, (NH4)2S, NH4HS) by liquid-phase oxidation in the presence of a heterogeneous phthalocyanine catalyst KSM. LOCOS technology is applicable in solving the following problems:neutralization of alkaline sulphurous effluents from oil refineries and alkaline pyrolysis effluents: LOCOS SA process
formation water treatment (treatment): LOCOS PW process
purification of aqueous process condensates: LOCOS PC processWhen using LOCOS technology to neutralize wastewater, there is no pollution of the atmosphere with emissions of hydrogen sulfide and sulfur dioxide. This method is characterized by low heat consumption and does not require continuous consumption of reagents. It provides a more complete removal of toxic malodorous sulfur compounds from wastewater: sulfides and mercaptides. The alkaline nature of the reaction medium and the relatively low temperature of the process make it possible to use carbon steel apparatus in the circuit.
The LOCOS technology does not require a large consumption of heat and reagents, does not pollute the atmosphere with hydrogen sulfide emissions, the technological scheme uses devices made of carbon steel.
The essence of the technology lies in the oxidation of toxic sulfides with air oxygen into inert, odorless sodium thiosulfate and sodium sulfate according to reactions (1-2). The process of waste disposal takes place in the presence of a KSM catalyst at 60÷70°C and a pressure of 0.5÷1.0 MPa.
9Na2S + 9O2 + 4H2O → 4Na2S2O3 + Na2SO4 + 8 NaOH (1)
9NaSH + 10O2 → 4Na2S2O3 + NaHSO4 + 4H2O (2)
The resulting sodium thiosulfate and sulfate are less toxic than sulfides, which makes it possible to send neutralized effluents to biological treatment facilities (BTP).
H2S: Hydrogen sulfide treatment
TECHNOLOGY OF LIGHT HYDROCARBON FEED TREATMENT FROM HYDROGEN SULPHIDE
(«H2S Removal-1» process)
Technology is used to treat hydrocarbon gases from hydrogen sulphide to a residual content of 10.0 ppm.
Treatment of dry and liquefied hydrocarbon gases from hydrogen sulfide by aqueous solutions of alkanolamines at 10-45 °C temperature.
Concentration of hydrogen sulphide in hydrocarbon gas feed is up to 1.0% by weight, residual content of hydrogen sulfide is not more than 0.001% by weight.
Schematic diagram of hydrocarbon gases treatment from H2S:Hydrogen sulphide containing hydrocarbon gas enters the cube of T-101 column equipped with plates on which chemisorption of hydrogen sulfide occurs by an aqueous solution of alkanolamine according to the reactions 1- 2. The regenerated aqueous amine solution is fed to the top plate of the T-101 absorber.
H2S + (HOCH2CH2)2NH = (HOCH2CH2)2NH2SH (1)
(HOCH2CH2)2NH2SH + (HOCH2CH2)2NH = [(HOCH2CH2)2NH2]2S (2)
Aqueous amine solution saturated with hydrogen sulphide is removed from the bottom of T-101 column, heated in the heat exchanger E-101 up to 120 °C and through the distributor enters the regenerator R-101. Regeneration of amine proceeds according to the following reactions:
(HOCH2CH2)2NH2SH = H2S + (HOCH2CH2)2NH (3)
[(HOCH2CH2)2NH2]2S = H2S + 2(HOCH2CH2)2NH (4)
From the top of R-101 regenerator, hydrogen sulphide and water vapors are sent through the condenser-cooler E-103 to the tank D-101. From the cube of R-101 regenerated amine solution is discharged into D-102 tank previously cooled in E-104 cooler to 40 °C. The gasses of aqueous amine solution regeneration from the top of D-101 tank are discharged through the knockout separator to the elemental sulfur production unit. Regenerated amine solution from the tank D-102 is fed to the T-101 column for irrigation by the pump P-102 A/B.
Complex regenerative treatment of hydrocarbon gases from hydrogen sulphide. Absence of toxic sulphide-containing effluents formation.
«PPS-1»: Synthesis of polyphenylene sulfide
TECHNOLOGY OF THE SYNTHESIS OF POLYPHENYLENE SULPHIDE
Polyphenylene sulfide (PPS, PPS) is a semi-crystalline engineering thermoplastic that is presented on the world market of superstructural materials in two modifications: the first is a cross-linked polymer, the second is a linear polymer with a highly ordered supramolecular structure.
Ideal for the production of complex extrusion profiles due to its strength characteristics. The material withstands high temperatures, pressure and exposure to aggressive chemicals. PPS complies with all required standards and specifications in these industries. Flame retardant by nature, UL94 class V-0.
Polyphenylene sulfide advantage is used as an alternative to plastics, metals, thermoplastics in the following areas:
– in mechanical engineering, aviation and automotive industries. The chemical resistance of the material ensures the possibility of contact of PPS products with fuels and lubricants, fuels, alkalis and acids without damage to these products;
– in the gas and oil industry, in the production of submersible pumps, products or parts operating in conditions of high humidity;
– in the field of electronics, electrical engineering, lighting engineering and so on. Super-rigidity, impact resistance, and dimensional stability make it possible to manufacture hollow products from PPS that are planned to be operated at elevated pressure: these are lamp sockets, lip seals, case products, structures with stiffeners.
Schematic diagram of obtaining PPS:A sulfiding agent is prepared in the R-201 reactor: sodium sulfide is synthesized, and excess water is stripped off. In the R-201 reactor in the temperature range 200÷230℃ in the environment of n-methylpyrrolidone (NMP), the stage of preliminary polycondensation of paradichlorobenzene (p-DCB) and sodium sulfide takes place. The final polycondensation is carried out in the R-203 reactor in the temperature range 240÷270℃. Next, the synthesized PPS is filtered and washed in an F-201 filter. The washed PPS is unloaded and sent for drying.
The essence of the process:
Obtaining polyphenylene sulfides, according to the developed domestic technology, is carried out by nucleophilic polycondensation of p-dichlorobenzene with hydrosulfide sodium sulfide in a mixture with sodium hydroxide in an aprotic dipolar solvent medium.
Polycondensation is carried out at a temperature of 200÷270°C. N-methylpyrrolidone is used as a solvent.
Advantages:Obtaining linear crystalline PPS with a degree of crystallinity of more than 80%.Polyphenylene sulfides have improved physical and mechanical characteristics.