Table 1 Rates and activation energies for dehydration of cyclohexanol.

From: Enhancing the catalytic activity of hydronium ions through constrained environments

Reaction conditions * Kinetic measurement Reaction temperature (°C) Ea (kJmol−1)
   160 170 180 190 200  
Cyclohexanol (0.32 M), 0.02 M H3PO4 Rate (mol l−1 s−1) 5.5 × 10−6 1.3 × 10−5 2.9 × 10−5 6.4 × 10−5 1.5 × 10−4 157±3
  TOF (molalcohol molacid sites−1 s−1) 1.4 × 10−3 3.5 × 10−3 8.6 × 10−3 2.1 × 10−2 5.6 × 10−2  
Cyclohexanol (0.90 M), 0.02 M H3PO4 Rate (mol l−1 s−1) 1.3 × 10−5 3.1 × 10−5 6.9 × 10−5 1.5 × 10−4 3.7 × 10−4 158±4
  TOF (molalcohol molacid sites−1 s−1) 2.9 × 10−3 7.6 × 10−3 1.9 × 10−2 4.4 × 10−2 1.2 × 10−1  
Cyclohexanol (0.32 M), 140 mg HBEA150 Rate (mol gHBEA−1 s−1) 3.7 × 10−6 1.0 × 10−5 2.6 × 10−5 6.4 × 10−5 1.8 × 10−4 164±3
  TOF (molalcohol molacid sites−1 s−1) 1.9 × 10−2 5.2 × 10−2 1.4 × 10−1 3.3 × 10−1 9.3 × 10−1  
Cyclohexanol (0.90 M), 140 mg HBEA150 Rate (mol gHBEA−1 s−1) 4.2 × 10−6 1.2 × 10−5 3.4 × 10−5 7.2 × 10−5 2.0 × 10−4 162±4
  TOF (molalcohol molacid sites−1 s−1) 2.2 × 10−2 6.2 × 10−2 1.8 × 10−1 3.8 × 10−1 1.03  
  1. *Reactor was pressurized with 50 bar H2 at ambient temperature and stirred vigorously at 700 r.p.m. The rates were determined from the formation of cyclohexene after the set temperature was reached. The concentrations denoted are based on the density of water at room temperature.
  2. Turnover frequency (TOF) is determined as olefin formation rate (mol l−1 s−1) normalized to the concentration of hydronium ions (H3PO4) or total BAS (HBEA). The concentration of hydronium ions in the H3PO4-catalysed experiments depends on temperature and cyclohexanol concentration.
  3. Activation barriers are determined from the Arrhenius plots for TOFs (a directly measured property).