Design a chemical reactor that can efficiently convert 100 kg/hr of propane gas to propylene gas at a temperature of 500°C and a pressure of 2 atm. The desired conversion rate is 90%, while minimizing the production of unwanted byproducts. The reactor must also be safe and economically feasible, with a maximum capital cost of $1.5 million and a minimum expected lifetime of 10 years. What type of reactor, catalyst, and operating conditions would you recommend and why?

Question

Design a chemical reactor that can efficiently convert 100 kg/hr of propane gas to propylene gas at a temperature of 500°C and a pressure of 2 atm. The desired conversion rate is 90%, while minimizing the production of unwanted byproducts. The reactor must also be safe and economically feasible, with a maximum capital cost of $1.5 million and a minimum expected lifeti

Answer 1

I would recommend using a fluidized bed reactor  FBR  for this process, as it offers several advantages for the propane to propylene conversion. FBRs provide excellent heat and mass transfer, which results in a uniform temperature distribution throughout the reactor. This helps to minimize the formation of unwanted byproducts and achieve the desired 90% conversion rate. Additionally, FBRs can handle large amounts of feedstock, making them suitable for the 100 kg/hr propane feed rate.For the catalyst, I would recommend using a chromium-based catalyst, specifically CrOx/SiO2, which has been proven to be effective in propane dehydrogenation reactions. This catalyst promotes the selective conversion of propane to propylene while minimizing the formation of byproducts such as methane and ethylene. The catalyst should be used in the form of small particles to maximize the surface area and improve the overall reaction efficiency.The operating conditions for the reactor should be maintained at the specified temperature of 500C and a pressure of 2 atm. These conditions have been shown to be optimal for propane dehydrogenation reactions using chromium-based catalysts. It is important to closely monitor and control these conditions to ensure that the desired conversion rate is achieved and that the formation of unwanted byproducts is minimized.To ensure the safety of the reactor, several safety measures should be implemented. These include installing pressure relief valves to prevent over-pressurization, using temperature sensors and control systems to maintain the desired temperature, and incorporating emergency shutdown procedures in case of any operational issues.The estimated capital cost of a fluidized bed reactor system, including the reactor vessel, catalyst, heat exchangers, and control systems, is approximately $1 million, which is within the specified budget of $1.5 million. The expected lifetime of the reactor is at least 10 years, provided that regular maintenance and catalyst replacement are carried out as needed.In summary, a fluidized bed reactor using a CrOx/SiO2 catalyst and operating at 500C and 2 atm pressure is recommended for the efficient conversion of propane to propylene with a 90% conversion rate, while minimizing unwanted byproducts. This design is both safe and economically feasible, meeting the specified requirements.