Unformatted text preview: CHE4473 Kinetics Spring 2015 Homework N°4: Design of Ideal Isothermal Reactors (Variable Density) Due Tuesday FEB 3rd 2015 In all these problems you should notice that when the reaction stoichiometry shows a variation in the number of moles and the reaction is in the gas phase concentration is a function of conversion _____________________________________________________________________________________________________ 1. A homogeneous gas-‐phase reaction A è3R has a reported rate expression at 215°C -‐rA = 10-‐2 CA½ [mol/Liter sec] Find the space-‐time (VR/v0) needed to reach 80% conversion (XA) of a 50% A-‐50% inert feed to a plug flow reactor (PFR) operating at 215°C and 5 atm (CAo = 0.0625 mol/Liter). __________________________________________________________________________________________________ 2. The homogeneous gas-‐phase decomposition of phosphine 4 PH3(g) è P4(g) + 6 H2 (g) proceeds at 649°C with the first-‐order rate -‐r(PH3) = (10/h) CPH3 a) What size of plug flow reactor (PFR) operating at 649°C and 460 kPa can produce 80% conversion of a feed consisting of 40 mol/h of pure phosphine? b) What size of plug flow reactor (PFR) operating at 649°C and 11.4 atm is needed for 75% conversion of 10 mol/hr of phosphine in a 2/3 phosphine-‐1/3 inert feed? __________________________________________________________________________________________________ 3. A gaseous feed of pure A (1 mol/Liter) enters a CSTR mixed flow reactor (2 Liters) and reacts as follows: 2A è R -‐rA = 0.05 CA2 [mol/Liter. Sec] Find what feed rate (v0) (liter/min) will give an outlet concentration CA = 0.5 Mol/Liter. __________________________________________________________________________________________________ 4. Gaseous reactant A decomposes as follows: A è 3R -‐rA = (0.6 min-‐1) CA Find the conversion of A (XA) in a 50% A-‐50% inert feed (v0 = 180 liter/min, CAo = 300 mmol/Liter) to a 1 m3 CSTR mixed flow reactor. __________________________________________________________________________________________________ 5. A 1 Liter/sec flow of a 20% ozone-‐80% air mixture passes through a plug flow reactor (PFR) at 1.5 atm and 93°C. Under these conditions ozone (O3) decomposes by the following homogeneous reaction 203 è 302 , -‐rozone = k Cozone2 k = 0.05 [Liter/mol . sec] What reactor size is needed for 50% decomposition of ozone? __________________________________________________________________________________________________ 6. For the first-‐order reaction A è B on a CSTR, start from the CSTR design equation to derive the expression kτ = X/(1-‐X) – What assumptions are made? Obtain an equivalent equation for the second-‐order reaction 2A è 5B (gas phase). ...
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- Spring '14
- Reaction, feed, 1 liter, 0.6 min