I work with a type of spectrometer (made by Picarro) that uses near-infrared lasers to measure the stable isotopic composition of water vapor. The samples measured are typically liquid water samples that are vaporized at 110 °C and then carried by a flow of dry air through the measurement cavity. If the water samples contain dissolved organics that are also vaporized at 110 °C (e.g., methanol, ethanol), then the resulting spectral measurement can be impacted if those compounds also absorb light at similar wavenumbers.
For a sense of scale, we typically inject 1.8 uL of water, vaporize the sample, and then introduce the vapor over the course of about 10 minutes. The dry air carries the sample vapor through the system at ~40 mL/min.
The current solution involves using a small flow-through reactor held at ~400 °C with a body material of glass and a catalyst that efficiently combusts the organic compounds. This is placed in the instrument flow path between the vaporizer and the analyzer. However, the catalyst has a limited effective lifetime.
I am interested in making a replacement device that will resistively heat a reactor to between 600 and 1,000 °C, which should (given the carrier gas is air, thus plenty of O2) efficiently combust any organics without the need for a solid catalyst. The wide range of temperature is because I do not know a priori what temperature is necessary to effectively combust all organics. In practice, I'd end up using the lowest temperature necessary to match the performance of our existing device.
My main question is, thus: what would be the best reactor material that satisfies the following conditions: (a) able to be safely heated to 600-1000 °C, (b) not be damaged by flowing water vapor, and (c) not engage in any meaningful side reactions with the water vapor. A small (d): as I'm in an academic lab, the material ideally is also relatively cheap.
My immediate thought was to use alumina, but I am now aware that there are opportunities for reactions with water and some alumina polymorphs that might change the isotopic composition of the water during travel through the reactor. My second thought is to use quartz, which I believe may be a good option. However, I am hoping someone with more familiarity in materials science could advise.