Vapor-Phase Cracking of Acetone

Here we consider a nonisothermal, nonadiabatic tubular reactor as a distributed system. Our objective is to find its steady-state concentration and temperature profiles. 

Our specific example involves the vapor-phase cracking of acetone into ketone and methane, described by the endothermic reaction 

This takes place in a jacketed tubular reactor. Pure acetone enters the reactor at a temperature of To = 1030 K and a pressure of P0 = 160 kPa. The temperature of the external cooling medium in the heat exchanger is constant at Tj = 1200 K. The other 

Our task is to determine the temperature and concentration (or conversion) profiles of the reacting gas along the length of the reactor. We assume constant pressure throughout the reactor. 

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Chapter 4.1 deals with an important industrial problem, the vapor-phase cracking of acetone. Here the material- and energy-balance design equations are developed. We advise the students to try and develop the design equations independently before consulting the book s derivations. Numerical solutions and MATLAB codes are developed and explained for this problem and sample results are given that need to be checked against those of the students codes. 

Jeffreys, in a treatment of the design of an acetic anhydride manufacturing facility, states that one of the key steps is the vapor-phase cracking of acetone to ketene and methane ... 

P8-23b The vapor-phase cracking of acetone is to be carried out adiabatically in a bank cf 10001 -in. schedule 40 tubes 10 m in length. The molar feed rate of acetone is 6000 kg/h at a pressure of 500 kPa. The maximum feed temperature is 1050K, Nitrogen is to be fed together with the acetone to provide the sensible heafof reaction. Determine the conversion as a function of nitrogen feed rate (in terms of ) for (a) Fixed total molar flowrate. 

Vapor-phase cracking of acetone, described by the following endothermic reaction ... 

Acetic acid is known to undergo a vapor-phase ketonization reaction with formation of acetone on Brpnsted acids in general, and on proton-zeolites in particular. On large-pore zeolites in their proton form, the ketonization reaction is followed by acid-catalysed self-condensation amounting to mesitylene, mesityl oxide and phorone as main products [1], the chemistry being essentially identical to that in mineral acids. In H-pentasil zeolites with suitable acid site density, phorone isomerises to isophorone, which is cracked to yield 2,4-xylenol [1]. With propionic acid a similar chemistry occurs, but the formation of phenolics is severely suppressed by transition-state shape-selectivity effects... 

Pure acetone is fed into an adiabatic PFR at a mass flow rate of 7.85 kg/h. The inlet temperature and pressure of the feed stream is 760°C and 162 kPa (1.6 atm), respectively. In a vapor-phase reaction, acetone (CH3COCH3) is cracked to ketene (CHjCO) and methane (CH4). The following reaction takes place ... 

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