All experiments were conducted with the same commercial catalyst (BASF S-3-86). The reactor has been filled several times with fresh catalyst samples. The fills are indicated as charge numbers. The catalyst was a leftover from a former PhD project (Vollbrecht 2007). A particle size fraction of 0.315-0.5 mm prepared by grinding pellets was used. To ensure almost ideal CSTR behaviour, a stirrer speed of at least 3000 rpm had been experimentally determined. Reported data acquired at < 3000 rpm may be affected by mixing non-ideality. The feed gas components had a purity of at least 99.97 vol.-%. The piping and devices were heated to avoid condensation. The total outlet flow rate was not measured. The reactor pressure was controlled with a dome pressure regulator which releases gas from the reactor to keep the desired value. If the set value of pressure is increased, the outlet flow rate is decreased to fill the reactor. Then, the flow rate to the analytics may be insufficient for proper analysis. Thus, the GC data measured during significant pressure changes in the reactor (not fluctuations < 0.5 bar) or at low reactor pressures (< 5 bar) need to be treated with care.
Fresh catalyst was reduced with 500 NmL/min of 2 vol.-% H
2 in N
2 at ambient pressure before use in methanol synthesis experiments. The temperature was increased from room temperature to 180 °C within 2 h and kept for at least 12 h (following the procedure of Vollbrecht, 2007).
At the beginning of an experiment, the actual reactants were dosed after the pressure was built up to the desired value with pure nitrogen. The experimental setup and the procedure will be described in more detail in a paper which is currently in preparation.
The file DataInfo.csv lists for every experiment the ID, the used charge of catalyst, the catalyst mass, the run time of the catalyst in the reactor since the first use in days, the free gas volume in the reactor and an approximately estimated catalytic activity. This activity is an indicator for the extent of irreversible deactivation over the lifetime of the catalyst, which needs to be taken into account for kinetic evaluation of the data. It is defined as the ratio of the carbon-based methanol yields measured at a reference steady state condition on the specific day to the initial value of the first conducted experiment using that catalyst charge. The applied reference conditions are provided below.
For every experiment two files exist, due to the different time resolution of the data recording from the PCS7 software (inlet, mostly every 1 s) and the measurements of the gas chromatograph (outlet, roughly every 90 s) . The Inlet files contain data for inlet component mass flow rates, reactor pressure, temperatures and stirrer speed over time. The Outlet files comprise the outlet component molar fractions over time.
Inlet conditions for activity determination:
xCO2 = 2.56%
xCO = 20.82%
xH2 = 60.59%
xN2 = 16.03%
Cat.Ch.Nr 5: 4.3072 g catalyst, 280 mL gas volume, 230°C, 30 bar, 2 NL/min
Cat.Ch.Nr 6: 4.3501 g catalyst, 286 mL gas volume, 230°C, 50 bar, 3.333 NL/min
References
Vollbrecht, B., 2007. Zur Kinetik der Methanolsynthese an einem technischen Cu/ZnO/Al2O3-Katalysator. Docupoint-Verlag. PhD thesis, Otto-von-Guericke-Universität Magdeburg.
