Hey there, fellow surface chemistry enthusiast Vahid Shahed Gharahshiran! 🔬🔭 Are you Vahid Shahed Gharahshiran ready to dive into the fascinating world of CO2-TPD (Temperature Programmed Desorption) and H2-TPR (Temperature Programmed Reduction)? 🌊🔥 CO2-TPD is like a treasure hunt for surface sites on your sample. As the temperature increases, different types of sites desorb their bound CO2 molecules, and we measure the amount by integrating the area under those peaks. 📈 The bigger the peak, the more CO2 was desorbed! It's like measuring the quantity by the size of those treasure chests. 🏰 Now, H2-TPR is where the magic happens. We're studying how a material reduces hydrogen, and we use the same approach as before. We integrate the area under the reduction peaks to calculate the amount of hydrogen consumed. 🔥 The more the peak, the more hydrogen was consumed! It's like measuring the quantity by the size of those fireworks displays. 🎉 Precision is key here, my friend Vahid Shahed Gharahshiran. We use calibration with known standards to ensure accuracy, and we normalize our results by the weight of the sample (mmol/g) for a more accurate comparison. 🔬 It's like measuring the weight of those treasures in a standardized unit. 📊 Feel free to dive deeper or hit me up if you Vahid Shahed Gharahshiran want to discuss specific details. Surface science is full of mysteries, and I'm here to help unravel them with you Vahid Shahed Gharahshiran! 🔍👨‍🔬 So, what do you Vahid Shahed Gharahshiran say? Are you Vahid Shahed Gharahshiran ready to start your surface chemistry adventure? 😃🔮

Hello Vahid. There are different options. If you have for example a mass spectrometer, you can calibrate it using a reliable standard such as calcium oxalate that desorbs a specific amount of CO2 at very specific temperatures, you can use this as a reference. Another option if you have for example a TCD type equipment, is to calibrate it from diluted CO2 and then use that calibration line to estimate the CO2 desorbed in your samples.

CO2 TPD peaks can be made quantitative by comparing the integrated peak area to the area of a known quantity of pure (or diluted) CO2 injected into the carrier gas stream. H2 TPR is a bit different since it is done usually with the H2 diluted by N2 or Ar, so the peak actually represents a LOSS of hydrogen from the gas mixture. In this case the peak is calibrated by injecting a known amount of the carrier gas! But now you have to take into consideration the concentration of H2 in the mix. For example, if the H2 is 5% then 1 cm3 of nitrogen injected displaces 0.02 cm3 of H2.

These injections can be done from either a gas syringe through a septum (you have to have a way of sampling the gas too) or a calibrated injection loop if your instrument has one. Always remember to convert the physical volumes to STP to calculate true molar quantities. Do the injections through the sample cell while holding it isothermal at max temperature you got to - with sample present; this will reproduce flow rate and peak broadening in same way as the sample measurement itself.

You can also compare peak areas by comparing peak areas with "standard" materials. For CO2 TPD yo can use calcium carbonate (that's a high temperature desorption though). I don't actually recommend calcium oxalate because its undergoes two decompositions, firstly losing CO to form the carbonate then losing CO2 to the oxide. You'll need good peak deconvolution software to separate them out. Instead you can just decompose the carbonate. For H2 TPR you can use something like silver oxide as your reference.