The “maker” movement is gaining widespread
attention,
especially in the field of laboratory education. Here we have built
a low-cost, “do-it-yourself”, open-source thermal conductivity
cell detector (TCD) for chemical laboratory analysis, which is assembled
from thermal conductivity gas sensor elements and 3D-printed flow
cell parts based on a Raspberry Pi Pico microcontroller. An ADS1115
digital-to-analog converter (with 16-bit acquisition resolution) is
used to acquire the electrical signal from the thermal conductivity
sensor response via a Wheatstone bridge. The device is programmed
to acquire data based on the open-source Thonny Micro Python IDE software
via I2C communication. Temperature programming analysis
(TPA) is an important technique to characterize heterogeneous catalysts;
therefore, we apply the assembled TCD to characterize the reduction
properties of commercial Cu/ZnO/Al2O3 catalysts.
The hydrogen temperature-programmed reduction (H2-TPR)
profile of the commercial Cu/ZnO/Al2O3 catalyst
shows a broad peak in the range of 150–250 °C with a peak
position at 213 °C, which is consistent with previous reports.
The total amount of hydrogen consumed by the commercial catalyst during
H2-TPR is 10.7 mmol/gcat, which can be calculated
from the calibrated H2 vol % TCD signal result and the
peak area of the H2-TPR profile. The results show that
the fabricated TCD detector exhibits excellent performance during
the testing process and is capable of meeting research-grade applications.
In summary, students will learn a wide range of skills in a hands-on
learning environment of a chemistry laboratory course.