1. (20 %) Glucose (C6H12O6) is being converted to hexane by reaction of glucose

Question

1. (20 %) Glucose (C6H12O6) is being converted to hexane by reaction of glucose with hydrogen (H2) according to Reaction 1 in a tubular reactor. The feed to the reactor has a molar hydrogen to glucose ratio of 30.0. Undesired methane (CH4) forms from Reaction 2. The glucose molar flowrate into the reactor is 100.0 mole/min. C6H12O6 + 7 H2 ? C6H14 + 6H2O (1) C6H12O6 + 12 H2 ? 6 CH4 + 6H2O (2) 1A) Write the material balances for each reactant and product in terms of molecular species flowrates and extents of reaction. 1B) Write material balances using atomic species balances. 1C) The conversion of the limiting reactant is 60.0%. The molar ratio of hexane (C6H14) to methane (CH4) in the outlet of the reactor is 3.00. Calculate the outlet molar flowrates of each of the reactants and products. Use the balances from Part A to solve this problem.

Explanation / Answer

C6H12O6 + 7 H2 ? C6H14 + 6H2O

(x)

C6H12O6 + 12 H2 ? 6 CH4 + 6H2O

(y)

moles of glucose entering= 100 moles

moles of H2 entering= 100*30 = 3000 moles

glucose is limiting reactant

conversion=60%

moles of glucose reacted = 100*0.6=60 moles

assume x moles of glucose reacted by reaction (1) and y moles by reaction (2)

if x moles of glucose reacts by reaction (1) then x moles of hexane will form

if y moles of glucose reacts by reaction (2) then 6y moles of CH4 will form

then (x/6y)=3 ---->(1)

    x+y= 60 ---->(2)

solve above two equations

y=3.16 moles and x=56.84 moles

C6H12O6 + 7 H2         ? C6H14 +    6H2O

(56.84)     (7*56.84)       (56.84)       (6*56.84)

moles of H2 reacted by reaction (1) = 7*56.84 =397.88 moles

moles of C6H14 formed by reaction (1) =56.84 moles

moles of H2O formed by reaction (1) = 6*56.84=341.04 moles

C6H12O6 + 12 H2    ?      6 CH4 +      6H2O

(3.16)          (12*3.16)            (6*3.16)      (6*3.16)

moles of H2 reacted by reaction (2)=12*3.16=37.92 moles

moles of CH4 formed by reaction (2) =6*3.16= 18.36 moles

moles of H2O formed by reaction (2) = 6*3.16=18.36 moles

outlet:

C6H12O6 = 100-60= 40 moles

H2=3000-(397.88+37.92) =2564.2 moles

C6H14 =56.84 moles

CH4 = 18.36 moles

H2O= 341.04 + 18.36 =359.4 moles

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