Production of thionyl chloride using the sulfur dioxide process

Production method: Currently, the main industrial methods for producing thionyl chloride are the chlorosulfonic acid method, the sulfur dioxide gas-phase method, and the phosphorus trichloride co-production method. Consumption quota: Production method, Raw materials and specifications, Consumption quota/t·t-1. Chlorosulfonic acid method: Chlorosulfonic acid (95%) – 1.1; Liquid chlorine (99%) – 0.91; Sulfur powder (99.5%) – 0.42. Sulfur dioxide gas-phase method: Sulfur (99.5%) – 0.22; Liquid chlorine (99%) – 0.88; Sulfur dioxide (99%) – 0.44. Co-production method: Phosphorus trichloride (98%) – 1.3; Liquid chlorine (99%) – 0.66; Sulfur dioxide (99%) – 0.64. In the sulfur dioxide gas-phase process, sulfur, sulfur dioxide, and chlorine are fed into a sulfidation bed equipped with activated carbon for reaction. Sulfur reacts with chlorine to produce sulfur dichloride. Sulfur dichloride, chlorine, and sulfur dioxide are recombined to form thionyl chloride. S+CL2---> SCL2 SCL2+CL2+SO2---> 2SOCL2

Reply to 2# cjg820: Does what was said on the second floor refer to a fluidized bed? Provide a detailed introduction. This is indeed a new technology

The sulfur dioxide gas-phase process is superior in this regard!

Brief description of the process flow: (1) Pretreatment of liquid chlorine and SO2: Liquid chlorine and SO2 are stored in cylinders, and before entering the reaction system, they need to undergo processes such as vaporization, buffering, drying, and preheating. First, the chlorine and SO2 stored in liquid form in steel cylinders are vaporized at around 80°C using a vaporizer; the vaporization pressures are adjusted to 0.4 MPa and 0.3 MPa respectively, after which the gases are fed into a buffer tank. The pressure of the gases in the buffer tank gradually stabilizes, ensuring a steady supply of material to the process system. Next, the desiccant, calcium chloride, is used to absorb the extremely small amounts of water present in the material, thereby ensuring the purity of the material entering the process system. Finally, the material passes through a preheater to increase its temperature in preparation for use in the synthesis process. The project includes a separate vaporization room, where liquid chlorine for various products and SO2 are both vaporized and processed there. (2) Synthesis of sulfur monochloride: 1250 kg of sulfur was lifted to the vicinity of the hopper using a forklift and manually fed into a 2000 L reactor (a slight negative pressure was maintained inside the reactor to prevent the formation of sulfur dust). Then, 1750 kg of chlorine gas was continuously introduced into the reactor. This is a gas-solid reaction; the chlorine gas enters the reactor from below via a distributor, where it reacts with sulfur at normal temperature and pressure. The resulting sulfur monochloride liquid is collected in storage tanks to serve as raw material for subsequent processes. This process is batch-based, with each batch being produced over 8 hours; after the completion of each reaction batch, the residual gaseous material in the reactor is drawn into the waste gas treatment system using an exhaust fan. During the process, strict control is exercised over the amounts of chlorine and sulfur added; all of the sulfur is converted. According to the principles of the reaction, this synthesis process produces sulfur monochloride as well as sulfur dichloride. (3) Sulfur dichloride synthesis: This process is carried out on a continuous basis. The reactants from the aforementioned process are passed through a distributor at a rate of about 222 kg/h, where they react with the introduced chlorine to produce sulfur dichloride; simultaneously, the bottom liquid from the distillation vessel is also introduced. The reaction temperature is controlled at around 55°C to vaporize the generated sulfur dichloride, thereby pushing the reaction equilibrium continuously in the direction of sulfur dichloride formation; the conversion rate of sulfur dichloride in this reaction exceeds 99%. (4) Synthesis of thionyl chloride: The reaction gases mentioned above first enter a mixer, where they mix evenly with the pre-treated SO2 as well as the light components that are recycled, and the mixture is then heated to the specified process temperature (around 150°C). It then enters the tubular reactor, where, in the presence of activated carbon (which is added in a one-time amount of about 1.5 tons per batch; under normal conditions it is replaced every 3 years, so it is not included in the equilibrium diagram), the reaction temperature is maintained between 200°C and 210°C to continuously produce sulfoxide chloride. This is a gas-phase reaction, and based on SO2, the reaction conversion rate is approximately 90%. The reaction proceeds continuously, with the light components being continuously recycled, resulting in an overall molar yield of around 98%; the conversion rate of side reactions is about 2% (based on SO2). (5) Sulfuryl chloride distillation: The gaseous crude product of sulfuryl chloride is processed by controlling the liquefaction temperature (around 65°C) to remove the low-boiling light components (under-reacted sulfur dichloride, chlorine gas, and SO2). These components are collected and returned to the mixing section where they mix again and continue to participate in the reaction, thereby ensuring as complete a reaction as possible and improving material utilization, which in turn increases the reaction yield. (6) Distillation: The crude sulfoxide obtained after fractional distillation is fed into a distillation tower, which is a composite tower. In the reaction section (sulfidation bed), sulfur dichloride and other components in the product react with sulfur to produce heavier components (sulfur monochloride). Maintain the process temperature at 75–80°C to vaporize thionyl chloride; the condensed product is then obtained as thionyl chloride ready for transfer to the product storage tank ； The resulting recycled fraction (bottom stream) is used in the sulfur dichloride synthesis process.

Request for process flow diagram and operating procedures: handshake

Request for process flow diagram and operating procedures: handshake

Poster: Kaifeng Dongda Chemical also did this before; if you want to know more, I can help you ask around. :) They have used our 3.3 high borosilicate glass equipment,

Looking for experienced sulfuryl chloride production managers